Focus 4: Global Change and Ecological Complexity

[Leader: Michel Loreau]
[Officer: TBA]

Introduction

GCTE's Focus 4 links two major areas of research that have worked largely independently up until now: global change and biodiversity. Changes in land use, atmospheric composition, and climate directly affect biodiversity and ecological complexity, and consequently ecosystem functioning ( Fig. 1). How important is this indirect effect of global change on ecosystem functioning? What kind of ecological complexities exist in natural systems? How much and what kind of ecological complexity can be changed before significant changes in ecosystem functioning result? Will changes in complexity, and consequent changes in functioning lead to feedbacks for further global change?

The objectives of Focus 4 are:

• to determine the relationship between ecological complexity and ecosystem functioning
• to evaluate how global change affects biodiversity and ecological complexity
• to elucidate major consequences of global change effects on ecological complexity and ecosystem functioning for policy and resource management.

The term "ecological complexity" is used here to refer to biodiversity in a broad sense. It includes the diversity of genotypes, species, functional types, and landscapes, the interactions within and between these levels of organization as well as the diversity and interaction of trophic pathways yielding the connectivity of ecosystems. Ecosystem functioning represents a collection of processes such as primary production, decomposition, and nutrient and water cycling, and their interactions. In this document we refer to "diversity" in case of diversity of genotypes, species (species richness), functional types, and landscapes without considering respective interactions within or between these groups. The term "complexity," however, refers to the diversity of interactions within and between these levels of organization including interactions between trophic levels.

Ecologists have already expended considerable effort in studying the diversity of organisms that inhabit the Earth, and the mechanisms that may account for this wealth of biodiversity. At this point, there is evidence supporting several hypotheses that diversity is a function of ecosystem properties. However, less information is available on the effects of ecological complexity on ecosystem functioning under current and global change conditions (Fig.7). A recent SCOPE project (Mooney et al. 1996) and UNEP's Global Biodiversity Assessment (GBA, 1995) have synthesized our current understanding of the effects of ecological complexity on ecosystem functioning. These two sources provide the starting point for Focus 4.

A recent analysis of future biodiversity trends in the biomes of the world showed that the two main reasons for biodiverstiy loss in the coming decades will be land-use change, mainly habitat loss and landscape fragmentation and the invasion of alien species into natural systems. Our understanding of the consequences of these changes to biological diversity for ecosystem functioning is still limited. Possible trends have become clear from early work. Experiments show a positive, saturating relationship between species richness and ecosystem processes, such as primary productivity. High biodiversity may buffer ecosystem functioning against unexpected effects of global change. There are three groups of species that strongly influence ecosystem functioning, those that modify (i) resource availability; (ii) trophic structures; or (iii) disturbance regimes.

Focus 4 aims to build on and extend the existing work with experimental, observational, modeling, and policy and management-oriented approaches, and to make this a coordinated international effort.

Focus 4 is divided into four Activities (Fig. 2). Activity 1 is designed to improve our understanding of the effects of ecological complexity on ecosystem functioning (Fig. 1) at the genetic, species, and functional type level; Activity 2 addresses similar questions at the landscape level. Activity 3 studies the effects of global change drivers on biodiversity and ecological complexity. Activity 4 examines the implications of global change induced changes in the relationship between ecological complexity and ecosystem functioning for some important resource management problems. Thus, Activities 1 and 2 address the fundamental relationship between complexity and functioning from a global change perspective, while Activity 3 explicitly examines global change impacts on this relationship and Activity 4 extends this knowledge to applications of importance for human societies.

Focus 4 has many strong links to the other foci of GCTE. In particular, there is much interaction between Focus 4 and Focus 2, Change in Ecosystem Structure. The latter does not address complexity per se and how it may influence ecosystem functioning, but aims to understand and predict the impacts of global change on ecosystem composition and structure, with an emphasis on the functional type approach and on structural change at the patch, landscape, regional, and global scales. At the patch and landscape scales, many experimental and observational studies will be carried out jointly by Foci 2 and 4. Much of the Focus 4 modeling effort will draw heavily on simulation tools already under development within Focus 2.

Close links will also be developed with Task 3.3.3, Global Change and Soil Biology, which has initiated a core research project on functional soil biodiversity. That work will be carried out jointly with Focus 4. In addition, close links will be established with Activity 3.4, Global Change Impacts on Complex Agroecosystems, which is studying the relationship between complexity and productivity of multi-species agricultural systems, and the effects of global change on this relationship. Collaboration will also be initiated with Activity 3.2, Global Change Impacts on Pests, Diseases and Weeds, on ecological controls on vectors of pests, diseases, and weeds.

Focus 4 is also a component (Core Programme Element 1) of DIVERSITAS. The link of Focus 4 with DIVERSITAS exists in the joint effort to answer questions on the effects of changing complexity on ecosystem functioning, ecosystem resilience and stability. The questions will be addressed at various spatial and temporal scales in the context of global change. DIVERSITAS, an international programme of biodiversity science, is a partnership of intergovernmental and non-governmental organisations to promote, facilitate and catalyse scientific research on biological diversity, its origin, composition, functioning, maintenance, and conservation. The goal of DIVERSITAS is to provide accurate information and predictive models on the status of biodiversity and the sustainability of the use of the Earth's biotic resources, and to build biodiversity science capability worldwide.

Figure 7

Activity 4.1: Effects of Ecological Complexity on Ecosystem Functioning
[Leaders: Michel Loreau]

Ecologists have long suspected that biodiversity influences ecosystem processes, thus, there is increasing concern about the impacts of the loss of biodiversity on ecosystem functioning. For instance, it has been hypothesized that primary productivity is positively correlated with plant species diversity. In a similar vein, it has been stated that the retention of limiting nutrients in ecosystem, and thus the long-term fertility of soils and the quality of water all depend on the biodiversity of ecosystems. Only a few of these ideas have actually been tested, however, mostly at single locations within single ecosystems, or with low replications across ecosystems. The ideas themselves are in their infancy and have not yet been fully developed theoretically. Because of the potential importance of ecological complexity for the long-term functioning and sustainability of ecosystems around the world, it is imperative that progress on understanding the complexity/functioning relationship be made rapidly. This Activity aims to develop an international, cooperative research programme, based on an integrated set of experimental, observational, and theoretical studies, to determine the strength and generality of the potential effects of ecological complexity on ecosystem functioning.

Activity 4.1 is structured in three Tasks. The first Task focuses on the effects of changing diversity at different levels of organization, i.e. genotype, species, and functional type, on ecosystem functioning. The second Task addresses how the invasion of exotic species into natural systems will alter ecological complexity and consequently affect ecosystem functioning. Task three will emphasize on the development of models and theories of the effects of ecological complexity on ecosystem functioning.

Task 4.1.1: Effects of Genotypic, Species, and Functional Type Diversity on Ecosystem Functioning
[Leader: Shahid Naeem]

Important to understanding the effect of ecological complexity on ecosystem functioning is the response of extant communities to the experimental deletion or addition of genotypes, species, and functional types, since these are likely scenarios under global change. Such experiments include the manipulation of both the diversity of ecosystems in terms of number of species only and the diversity in terms of the potential importance of particular genotypes, species or functional types for ecosystem functioning (its "per capita impact"). The effects of manipulative organism addition or deletion on ecosystem processes, such as primary productivity, nutrient retention and trace gas emissions, will be determined. The effects changes in both above- and below ground diversity need to be understood, thus, emphasis will be placed on the manipulation of the diversity of soil biota as well as of plants. Initially, the effects of altered biodiversity on below- and aboveground functioning will be studied independently; interactive effects will be addressed in a next step.

Because manipulations in natural ecosystems are likely to be difficult and should be long-term, the construction of synthetic communities in the field or laboratory provides a valuable alternative in some instances. In addition to their logistical advantages, synthetic ecosystem experiments are also valuable when large numbers of replications are required, when resources are limited, and as testing grounds for hypotheses (e.g., examination of the effects of a single important factor or interactions among factors in a multifactorial experiment). Laboratory experiments are useful for three main reasons i) to create conditions that would be technically difficult or expensive to establish in the field (e.g. manipulation of trace gas concentrations, changes in temporal patterns of water availability), ii) to deal with organisms or processes that are too dangerous or inappropriate for testing in the field (e.g. pathogens, exotic species), and iii) to provide controls for field experiments (plant deletions in the field inevitably have side effects).

As a complement to manipulative experiments involving natural ecosystems and synthetic communities, existing gradients and historical manipulations for other purposes can also be used to examine the relationship between complexity and ecosystem functioning. These studies are most useful when logistical and cost considerations preclude the use of direct manipulations. For example, the temporal and spatial scales necessary to capture forest dynamics make such ecosystems less tractable and much more expensive than herbaceous communities for experimental manipulation, particularly, for a wholescale synthesis of forest communities. In addition to their advantages in terms of logistics and costs, many of these natural experiments have existed for decades and provide an opportunity to gather results in a long-term context, a perspective, otherwise impossible to gain from new manipulative experiments.

Objective

• To understand the ecosystem effects of genotypic, species, and functional type diversity on ecosystem functioning across a range of ecosystem types.

Implementation

This Task will be implemented through networks of three types of experiments, (1) field manipulations of biodiversity, (2) construction and study of synthetic communities, and (3) natural and opportunistic experiments.

Field manipulative experiments: One set of experiments will be conducted to remove the genotype, species, or functional type with the greatest relative importance for ecosystem functioning. For instance, a network of experiments will be established to monitor the effect of removing a plant species or functional group that contributes the most to net primary production. Results will yield initial insights into the complexity/functioning relationship in ecosystems. Another set of experiments involves a reciprocal transplant approach including both additions and deletions of genotypes, species, or functional groups. For instance, in semiarid regions the potential dominant functional types of plants are grasses or shrubs/low trees. On sites dominated by grasses, the grasses would be removed and replaced with woody plants, and the effect on ecosystem functioning measured. Sites dominated by woody plants would receive the opposite treatment.

Synthetic communities. Two types of studies are planned. The first involves the construction of experimental communities allowed to grow under natural field conditions. The manipulated variable in these synthetic communities is the diversity of any of their components. For instance, diversity may be manipulated at any trophic level (e.g., decomposers, primary producers, herbivores, pathogens, etc.), or across the entire foodweb, or across functional groups within a trophic level, or across genotypes within one or more species. Although many designs are possible, an important feature is to have randomly chosen combinations so that the compositions of communities that differ in diversity (of genotypes, species or functional types) are an unbiased subset of a pool of biodiversity. Once established, the effects of changes in diversity, and the resulting changes in ecological complexity on a variety of population, community, and ecosystem processes will be monitored. The advantage of performing such experiments in the field is that these communities will experience natural environmental conditions (e.g. variation in local climate, soils, etc.), and thus results from these studies allow stronger inference to natural ecosystems.

The second type of study involves the construction of synthetic communities under more controlled laboratory/glasshouse conditions. There may be a series of questions and processes for which laboratory and glasshouse facilities are better suited than the field.

An international set of field experimental studies will be an important integrating facility for GCTE, contributing to Foci 1 and 2 as well as to Focus 4.

Natural and opportunistic experiments. Existing diversity gradients and opportunistic experiments, studies in which systems were exploited or manipulated for other purposes, provide further techniques for examining the complexity/functioning relationship. An example of the former is the strong diversity gradient in mangrove forests from northern Australia through Fiji to Samoa. All of these systems exist in the same climatic zone but differ greatly in their complexity, thus allowing the influence of complexity on functioning (e.g. productivity) to be estimated. An example of the latter is a comparison of monodominant or species-poor forests or those which have been selectively logged with adjacent species-rich patches across a range of forest ecosystems.

In addition to field surveys and observations, another component of this Task will be a comprehensive literature review of past studies that have employed a gradient approach. The literature review will help to survey ongoing research, to summarize and synthesize current knowledge, but most importantly to identify the gaps in our knowledge for future experimental or observational studies.

Much valuable data and insight into global biodiversity can be gained from careful and continual monitoring and inventory of taxa, their interactions, and their habitats. Thus, this Task will work closely with the Core Programme Element 4 of DIVERSITAS, Monitoring of Biodiversity, to design an appropriate and effective biodiversity monitoring network.

Proposed Timetable

• 1998 State-of-knowledge workshop
  Product 1: Synthesis volume on the effects of genotypic, species, and functional type diversity on ecosystem functioning.
  Product 2: Design of experiments and observational studies, and identification of initial network members and coordinating groups
• 1998/99 Inclusion of additional members in networks.
• 1999 Workshops to exchange initial results from experiments

Task 4.1.2: Effects of Biological Invasions on Ecological Complexity and Ecosystem Functioning
[Leader: TBA]

Human activities have long been responsible for the invasion of undesirable organisms into many ecosystems worldwide. Further expansion of exotic species are expected as a consequence of changes in global socioeconomic systems, land-use/cover change and changes in the abiotic environment. Biological invaders can affect human populations directly (e.g., spread of disease), or indirectly (e.g., decreased ecosystem stability or agricultural productivity, loss of native species).

Two related aspects are important in considering the invasion processes. One is the direct influence of invading organisms on ecosystem functioning. The other is the potential role of the complexity of particular communities and the nature of the invader in determining whether or not an invader is successful. Important lessons can be learned from invasion events that have already taken place (unplanned invasion experiments). Comparative studies will involve gathering information of past invasion events of exotic species in natural communities (e.g., "annualization" of perennial rangelands of the Great Basin in the US) and monitoring current invasion events. The comparative approach will provide specific testable hypotheses to be addressed in experimental manipulations. These hypotheses may be based on questions such as (i) what ecosystem types (in terms of resource base and complexity) are prone to be invaded (invasibility); and (ii) is there a set of characteristics which makes an organism a potentially successful invader in every system, or does it vary with different ecosystems?

Objectives

• To determine the effects of biological invasions on ecological complexity and ecosystem functioning.
• To determine the characteristics that make an ecosystem vulnerable to invasions.
• To determine the characteristics that make an organism a successful invader.

Implementation

Comparative studies of existing sites of invasion are useful and readily implemented. However, they lack the control of factors that experimental manipulations would provide. Two types of experiments are planned across biomes to examine the relationship between complexity, ecosystem functioning, and invasibility. First, introducing a variety of exotic species into a single community will help to determine the traits that make an organism a successful invader. Second, introducing a single exotic species into communities with varying complexity, but similar overall functioning (e.g. primary productivity), will help to determine whether ecosystems with low diversity are more or less vulnerable to biological invasion than ecosystems with high diversity. Monitoring ecosystem functioning in both types of experiments is expected to elucidate key mechanisms that are responsible for potential relationships between the complexity, functioning, and invasibility of ecosystems. Care must be taken in the execution of such experiments to ensure that the invasions are carefully controlled. The field experiments with synthetic communities (Task 4.1.1) may offer excellent opportunities to undertake such manipulative studies on species invasions.

GCTE's Activity 3.2 is carrying out research on the global change impacts on weed distributions and dynamics, and their effects on agricultural production. Thus, Task 4.1.2 will be closely coordinated with this Activity. The AMIGO (American Interhemisphere Geobiosphere Organization) programme is developing a study to document and understand invasions in the Americas. GCTE Focus 4 will collaborate closely with this programme and also with the SCOPE global invasions strategy programme.

Proposed Timetable

• 1998 State-of-the-knowledge workshop
  Product 1: Synthesis volume on (i) the effects of biological invasions on ecosystem functioning, and (ii) the characteristics of ecosystems prone to invasions and the nature of successful invaders.
  Product 2: Design of observational studies and experiments, establishment of networks, identification of initial contributing projects, and formation of coordinating groups.
• 1999 Inclusion of additional members in networks.
• 2000-2001 Workshops to exchange initial results from studies

Task 4.1.3: Theory and Models of the Effects of Ecological Complexity on Ecosystem Functioning
[Leader: Steve Pacala]

The nature of relationships between ecological complexity and ecosystem functioning likely depends on factors (e.g. water and nutrient availability) that govern the coexistence of species. Many of these factors are predicted to be altered under global change. Theories currently under debate can be categorized into those that relate coexistence to: (i) competition and differential colonization; (ii) partitioning of resources across space; (iii) partitioning of resources across time; (iv) multiple trophic level interactions; and (v) some or all of the above.

Using these concepts as a basis for simple ecological models allows us both to examine questions relating biodiversity and complexity to ecosystem functioning and to address the generality of these relationships across systems. Because modeling reaches its maximum potential when included as an integral part of research programmes (as opposed to being brought in as a last-step effort of data synthesis), these modeling activities will be carried out in close conjunction with the experimental and observational components of Activity 4.1. A hierarchical approach will be applied, from simple, theoretical models to data-driven process models that can be parameterized along diversity, resource and disturbance gradients.

Objectives

• To provide a theoretical framework with which to view the effects of ecological complexity on ecosystem functioning under global change
• To use this framework as a platform for generating new hypotheses regarding complexity effects on ecosystems.

Implementation

This Task will be implemented through the development, testing, and application of three types of models.

Theoretical models. As a first effort, simple models that are based on the above theories of species coexistence should be constructed to generate and examine hypotheses on interactions between complexity and ecosystem functioning, and of equal importance, whether these relationships are general across ecosystems and how they are influenced by a changing environment.

Models of biomes or ecosystem types. Building on the above theoretical models, important ecosystem processes (e.g. photosynthesis, transpiration, herbivory) should be included to create process models that allow more rigorous examination of ecological complexity / ecosystem functioning interactions. For example, differences between species often relate to life-history traits that reflect trade-offs between different methods of obtaining resources. Models based on important ecological processes that include such trade-offs among species and functional types can be applied across resource and disturbance gradients to make explicit predictions of the effects of complexity on various ecosystem processes. Complexity in this case would relate to the presence or absence of particular life-history traits as opposed to particular species. In order to achieve this, both positive and negative feedbacks of all included traits need to be considered under varying environmental conditions (e.g. temperature x moisture x nutrients). Those kinds of models could then be used to extend predictions to a variety of global change scenarios. Close collaboration with Activities 1.4 (Focus 1 Integrating Activities) and 2.1 (Patch Scale Dynamics) will be essential to construct the linked models proposed here.

Site-specific data-driven models. A third type of model should include trade-offs between different ecological strategies (life history attributes) as described above, but with data-intensive parameter estimation for all species at a given site. This will allow the examination of how various species assemblages affect ecosystem functioning under various environmental (i.e. site specific) conditions. For these models it is crucial to capture a wide range of variation of species traits rather than just average species conditions. Such models will be constructed and applied as an integral part of field experiments and observational studies throughout Focus 4. They are highlighted here as a comparative simulation tool for theory based models that will be developed in this Task.

Proposed Timetable

• 1998 Initial model intercomparison

Activity 4.2: Effects of Landscape Complexity on Ecosystem Functioning
[Leader: TBA]

The complexity of landscapes is determined by the number of ecosystem types, their characteristics (e.g. in terms of structure and functioning), their size and shape, and their connectivity. A large amount of evidence suggests that complexity at this scale may have large consequences on regional to global scale processes. For instance, the presence and arrangement of keystone ecosystem types such as wetlands or riparian areas often determine total carbon and nitrogen balance of a region. The critical questions to be addressed in this Activity are: (i) What effect does landscape complexity have on ecosystem functioning at large scales? (ii) How do these relationships between complexity and functioning vary with ecosystem processes of interest? (iii) How will global change affect landscape complexity, and in turn ecosystem functioning?

Activity 4.2 is organised around three Tasks, each addressing a different type of ecosystem functioning. The first Task focuses on ecosystem processes related to the transfer of matter and energy across landscapes and between the land surface and the atmosphere. Examples of such processes are productivity, biogeochemical cycles, surface hydrology and water, and energy exchange. The second Task is concerned with the extent to which landscape complexity influences movement of organisms across landscapes, and addresses such phenomena as migration and the viability of isolated populations. The third Task deals with the interaction of landscape patterns and regional disturbance regimes. For example, landscape patterns influence the spread of fire and the probability of logging, which in turn govern large-scale ecosystem functioning. Although matter and energy exchange, movement of organisms, and disturbance will be treated largely independently in the three Tasks, there are interactions between them (e.g., migration across landscapes of new functional types which affect nutrient cycling and probability of fire). Such interactions will be addressed at the Activity level as part of a synthesis of the three Tasks.

This work will be carried out in close collaboration with Activity 2.2., which is developing a suite of observational studies and models to scale up from the patch level understanding of ecosystem dynamics to the landscape and region level. Tasks 4.2.1 and 4.2.2 will be carried out jointly with Activity 2.2, the latter will underpin population dynamics studies. Task 4.2.3 will be carried out primarily in Activity 2.2 with input, as appropriate, from this Activity.

Task 4.2.1: Global Change, Landscape Complexity and Ecosystem Functioning (to be carried out jointly with Task 2.2.4)
[Leaders: Michael Apps]

Many ecological processes of interest in global change studies, such as productivity, biogeochemical cycling, and water and energy exchange, operate at a number of scales. While most process level research is conducted at the patch scale, our understanding of ecosystem processes should be extended to the global scale. To date, many global models on ecosystem processes are based on direct extrapolations of process understanding at the patch scale and ignore potential confounding effects of landscape scale phenomena. This Task deals with the direct linkage between the effects of changes in landscape complexity and ecosystem functioning, and how this linkage interacts with global change.

The critical question is when can ecosystem processes simply be aggregated as an area-weighted sum of patches, and when does distribution and patchiness, rather than just abundance of landscape elements affect these processes? Further, when must material and energy exchange among landscape units be considered to develop adequate estimations at large scales? These questions can be addressed with a series of analyses of increasing ecological complexity.

The first level of analysis in a global model approach is based on simple aggregation, in which the value for a process over a landscape is the average by area of the patch-specific values. Predictions using this "null model" are then compared with the next level of analysis, in which not only the abundance but also the size distribution of patches is considered. At this level of analysis coupling of patches will need to be considered to detect landscape scale effects of ecosystem processes caused by patch distribution. In the third level, the analysis would need to consider size distribution, and spatial organisation of landscape elements such as adjacency, interspersion, and connectivity.

The goal of this three-pronged approach is to classify the conditions under which explanations at each of those levels will suffice to explain and predict landscape or regional processes.

Objectives

• To determine the effects of changes in landscape complexity on ecosystem functioning, such as biogeochemical cycling and primary productivity.
• To predict how global change will affect the relationship between landscape complexity and ecosystem functioning.

Implementation

There is already considerable existing research on techniques for averaging physical transport processes, such as trace gas emissions and water and energy exchange between heterogeneous landscapes and the atmosphere. The implementation of this Task will begin with a review of this work and with an emphasis on its applicability to the ecological processes of interest. The critical question is to determine those circumstances where an area-weighted average is an inadequate technique for aggregation.

A second initial objective of the Task is to establish a network of comparative studies in order to relate aspects of landscape complexity to integrated measures of landscape processes. The analyses will require both techniques to index different landscape "patterns" in ecologically relevant ways and synoptic measurements of ecosystem processes such as net primary productivity, gas emissions, and movement of nutrients via hydrological pathways. The goal is to identify key features of landscapes that provide powerful predictors of process at large scales. Metrics will be developed for features that include aspects of pattern (e.g. size, shape, number, and location) and aspects of functioning (e.g., source/sink relationships). These metrics will be related with process measurements to determine which metrics provide the most powerful predictors of aggregated process values, and how much information about landscape complexity is needed to predict large-scale process values.

Estimations of the effects of global change on ecosystem functioning at the landscape scale can then be obtained by driving the models of complexity/functioning with projections of land-use/cover change, which will be developed by LUCC. Such linked models should also examine how past land-use legacies affect current ecosystem processes and future trajectories of land-use change. A focus of the analysis will be to detect dynamic responses such as time lags, threshold effects, or the amplification of these responses.

A future goal of this Task is to project the interactive effects of land-use/cover change and climatic change on the complexity of landscapes and the consequent impacts on ecosystem functioning.

For this Task it will be a good opportunity to explore the use of the Internet for new ways of communicating for the international ecological community. The goal will be to have an electronic workshop that represents a highly interactive setting, in which graphics, satellite imagery, photographs, text comments, mathematical equations and examples, small models, and voices are part of the communication modes for stimulating discussion and debate.

Proposed Timetable

• 1998 Electronic workshop for review of metrics of landscape complexity with important determinants of large-scale ecosystem functioning. Product synthesis papers.
• 1999 Workshop to refine the implementation plan, establish the design of modeling studies, standardize the methodology of analyses, and identify the initial networks of research groups and projects.
• 1999-2000 Initial synthesis

Task 4.2.2: Global Change, Landscape Complexity, and Animal Population Dynamics
[Leader: TBA]

Global change, via changes in average environmental conditions or extreme environmental events, and intense land use management, will increase the rate of species extinction in isolated habitat fragments. Isolation will make it extremely difficult for many taxa to migrate to environmentally more suitable conditions as climate changes. Changes in land use and cover, and hence landscape complexity, compound these problems. Loss of key species, such as top predators, fruit dispersers and pollinators from habitat fragments may severely disrupt ecosystem functioning.

The goal of this Task is to determine the consequences of changes in landscape complexity on population dynamics, and on the viability of isolated populations of key species and taxa, including their ability to migrate between landscape elements.

Objectives

• To determine how changes in landscape complexity affect animal population dynamics, with an emphasis on the viability of isolated populations and their ability to move between landscape elements.
• To predict how global change will affect the relationship between landscape complexity and animal population dynamics.

Implementation

The first stage in the implementation of this Task is to determine what the important metrics of landscape complexity are, the identification of key indicator species and groups, and data of relevance for population processes. Important characteristics of landscape elements include size distribution, shape, distance, and connectivity of landscape elements. Relevant species, guild, or functional type data will provide information on life history characteristics, relative abundance, spatial and temporal distributions within the landscape (full census), and body weight distributions. The associated modeling activities will aim to predict the viability of isolated animal populations in isolated habitat fragments with different numbers of individuals and life-history characteristics under changing average and extreme environmental conditions.

Proposed Timetable

• 1998 Participation in electronic workshop (see 4.2.1) to identify crucial metrics of landscape complexity to population dynamics. Literature review to synthesize known patterns and principles of the effect of landscape complexity on population dynamics.
• 1998 Workshop to develop detailed work plan on the connections between life history attributes and landscape complexity metrics, and potential collaborative modeling activities.
• 1999 Workshop to discuss the impact of landscape structure (e.g. Habitat fragmentation) on species migration and population dynamics.

Task 4.2.3: Global Change and the Interaction of Landscape Pattern with Disturbance Regime
[carried out by Activity 2.2]

Many landscape patterns, such as treefall gaps in tropical forests or forest patches of different successional age, are the consequences of regional disturbance regime, e.g., through changes in land-use. Conversely, these landscape patterns influence the probability of windthrow, fire and other disturbances. Most research on disturbance in the past has focussed on patch-scale studies with an emphasis on community or ecosystem responses to disturbance and recovery from disturbance with relatively little attention to the impact of landscape patterns on the probability of disturbance.

Human activities have long been a source of disturbance in ecosystems. However, the magnitude of human impacts is rapidly increasing, i.e., altering land cover types, fire regimes, and the pattern of habitat fragmentation in the landscape. For this reason it is imperative that we improve our understanding of the interaction of landscape pattern and disturbance regime.

Objective

• To understand the interaction between landscape pattern and disturbance regime under global change aspects.

Implementation

Focus 2 has a strong programme considering landscape consequences of disturbance. Focus 4 will participate in these activities to ensure that landscape-disturbance interactions are not ignored in Activity 4.2. Besides, this Task will emphasise on the effects of landscape structure on insect outbreaks as a disturbance. Even though Focus 4 will not initiate any independent projects in the immediate future, it will develop joint activities with T.2.2.2 to tackle the impacts of insect outbreaks.

Activity 4.3: Effects of Global Change on Ecological Complexity
[Leader: Volkmar Wolters]

Current rates of regional and global species extinction are several orders of magnitude greater than at any time in recent history. Driving forces include rising human population density, pollution, and habitat degradation and destruction. At the same time, the introduction of undesirable organisms (including human commensals, pests, and weeds) increases the proportion of alien species in natural systems in all continents and thereby homogenizes the species pool of previously distinct fauna and floral regions.

Unprecedented human population growth during the past centuries conferred massive land use changes and thereby exacerbated problems like accelerated species extinction, homogenization and fragmentation of natural and semi-natural ecosystems, and disruption of species interactions. Moreover, superimposed over these recent global changes, global climate and atmospheric composition are forecasted to change at least as rapidly as they did at the end of the Pleistocene, a period of massive worldwide disruption of biodiversity. There is unambiguous evidence that changes in atmospheric composition have been well underway for several decades, and there is some indication that the signal of climate change has emerged from its background. Given the empirical evidence linking climate and atmospheric composition to ecological complexity, and ecological complexity to ecological structure and functioning, it is important to understand better the potential impacts of climatic and atmospheric change, i.e., together the biophysical changes, on biodiversity and ecological complexity.

Land use has historically been constrained by climate, technology, and economics. In recent times technological innovations have created new combinations of climate and land use. New technology and economic scenarios allow pristine areas of the world to be logged, burnt and frequently be cultivated. All these changes create an urgent need for more research on the interaction of changes in land use with climate and atmospheric composition and on the direct impacts of land use change on biodiversity and ecological complexity. Task one will address the interactive effects of biophysical drivers (i.e., change in climate and atmospheric composition) on biodiversity and ecological complexity. Task two will focus on the effects of land use on biodiversity and ecological complexity. Task three will provide a theoretical framework to predict the response of ecological complexity to global change.

In a first phase, the effects of the major drivers of global change on biodiversity and ecological complexity will be examined individually. In a second phase, the interactive effects of changes in climate, atmospheric composition, and land-use will be addressed.

An important linkage of this Activity is the on-going effort to develop a global network for monitoring biodiversity (cf. DIVERSITAS Programme Element 4) and for the conservation, restoration and sustainable use of biodiversity (cf. DIVERSITAS Programme Element 5). Improvements in inventorying and monitoring biodiversity will significantly complement all three Tasks. The component of the DIVERSITAS Programme 5 on the integration of sustainable land use practices with biodiversity conservation will be valuable for Task 4.3.2 on effects of land use on biodiversity.

A cross-cutting theme in this Activity is the emphasis of effects of global change drivers on below ground diversity, thus close collaboration with the DIVERSITAS Special Target Area of Research Element 6 on Soil and Sediment Biodiversity will be pursued.

Besides, experimental efforts should be linked with T3.3.3 on Global Change and Soil Biology, to evaluate the effects of global change on soil biodiversity.

Task 4.3.1: Interactive Effects of Biophysical Changes on Biodiversity and Ecological Complexity
[Leader: Fakhri. Bazzaz]

Until recently, experimental investigations of the impacts of global and regional changes have (i) provided a separate focus on climate or atmospheric chemistry, and (ii) emphasized short-term studies. There is now an urgent need for long-term experiments across a wide range of climates to measure the interactive effects of changing climate and atmospheric composition on ecosystems of contrasting biodiversity and ecological complexity worldwide. The logistics and potential costs of such multifactorial manipulations present a major challenge to the ingenuity of experimental ecologists. New experimental designs may be required and, wherever possible, cost savings should be sought, e.g., by connecting with existing programmes involving manipulations of climate or atmospheric chemistry.

Objective

• To develop a global network of experiments to examine the effects (individually and interactively) of changes in global climate and atmospheric composition on biodiversity and ecological complexity

Implementation

The implementation of the Task aims, (i) to devise compact experiments with factorial combinations of altered climate and atmospheric inputs; (ii) to conduct experiments across a wide range of climatic zones and ecosystem types; (iii) to ensure that methods of data collection at each experimental site are appropriate to detect the rate and direction of changes in various above- and below-ground components of biodiversity and ecological complexity; (iv) to plan manipulative experiments in conjunction with modeling activities to allow comparisons of predictions of changes in biodiversity and ecological complexity derived by the model with experimental results; and (v) to conduct experiments of similar ecosystem types with contrasting biodiversity and ecological complexity. This could be achieved by utilizing existing local differences or by deliberate manipulation of complexity within one ecosystem (by removals or additions).

At a launching meeting of Activity 4.3, the general consensus was that of a large number of environmental variables related to atmospheric composition (CO₂, O₃, SO₂, NO₂, UV-B) elevated CO₂ and N-deposition will be the first two variables to be studied extensively, out of logistical and economic reasons. The existing GCTE elevated CO₂ consortium of Focus 1 clearly provides an excellent opportunity to take up the ongoing biodiversity work within this consortia and in a parallel effort to initiate new biodiversity related work with FACE experiments. A joint F1-F3-F4 effort could become one of the first major cross-Foci GCTE network, where questions on elevated CO₂ will be addressed both on the whole ecosystem level and on biodiversity and ecological complexity issues. This joint approach has two benefits, first, preliminary data will become available fairly quickly. Second, this manipulation can be achieved without major technical developments and at low costs and low logistical support.

Manipulation of N-deposition can be achieved without major technical developments and at low costs, thus can be conducted in many different ecosystems worldwide. Close collaboration and joint experimental efforts with Activity 1.2 Terrestrial Ecosystem Biogeochemistry should be fostered wherever possible.

The most pertinent climate drivers affecting ecosystems include temperature, precipitation, seasonality, and disturbance factors (e.g., frost, drought, storms, erosion, flooding, etc.). Extreme events and mean trends may act directly on ecosystems and their composition of species. Although plants and animals have evolved plastic responses to cope with seasonal extremes and stress events, there are limits to adaptability. Once species are no longer able to respond, since the thresholds of their physiological tolerance is passed, species get eliminated from a system, new species invade the system and the system as a whole changes. It will be a research priority of this Task to establish the number of species within functional groups which confer resilience in response to climatic extremes. It will also be important to examine to which degree soil biota respond similarly or differently to extreme climate and stress events compared to aboveground biota and how this will affect the whole ecosystem response. As a first step, it will be important to examine the direct effects of increased temperature on below and aboveground diversity of different ecosystems. Focus 1 will initiate a Warming Consortium in spring of 1998, to monitor and evaluate whole-ecosystem responses to global warming with possible feedbacks to the climate system. There are currently 26 sites with warming experiments worldwide comprising deciduous and coniferous forests, perennial grasses, tundra, polar deserts and watersheds. These experimental sites as well as other gradient studies should be employed to examine warming effects on the composition and diversity of systems. Thus, close collaboration with the Warming Consortium should be fostered to jointly investigate direct and indirect effects of elevated temperature on biodiversity and ecological complexity. In a separate effort, sites or regions highly vulnerable to extreme events (regions to be affected by ENSO, etc.) should be monitored closely to track system changes associated with the impacts of extreme events, in particular changes in biodiversity and ecological complexity. This should become an ongoing long-term effort.

It is recognized that the proposed approach, i.e., initially testing only three environmental variables, involves the risk of not including other important driving variables in some key sites located in remote areas. However, studying these three environmental variables, individually and interactively will allow a quick start of the activities of this Task. An important activity during the later phases of the programme will be to expand the range of sites and environmental variables at which expensive or technically-demanding manipulations are applied.

Proposed Timetable

• 1998 General planning meeting to design experiments and associated modeling activities (Task 4.3.3). Attend the next workshop of the CO₂ Consortium and the inaugural meeting of the Warming Consortia "The role of Ecosystem Warming Experiments in Global Change Research" in spring of 1998. Identify new network members and schedule future interim exchange workshops.
• 1999-2000 Synthesis of first results; expansion of network to additional sites. Inclusion of other environmental variables.

Task 4.3.2: Effects of Land use Change on Biodiversity and Ecological Complexity
[Leader: Valerie Brown]

An analysis of biodiversity scenarios for the major biomes of the world showed that the main reasons for a decline in biodiversity in the coming decades are directly related to land use change, i.e., habitat loss and landscape fragmentation and the invasion of alien species into natural systems. Land use change can have dramatic, and often rapid impact on biodiversity and ecological complexity. Although changes in land use are used to derive estimates of biodiversity loss, research into the mechanisms underlying the effects of land use change has been neglected both in terms of scientific investigation and evaluation and donor support. In the short term, changes in land use and land cover will have a greater impact on biodiversity and ecological complexity than biophysical changes. Policy, legislation, and economic incentives all influence land management and thereby influence biodiversity and ecological complexity directly and indirectly. Two major drivers of land use change account for a drastic change in biodiversity and ecological complexity, first, those due to expanding urbanization and concomitant landscape fragmentation and second those associated with the intensification of production systems (i.e., agriculture, plantation forestry, forestry, fallow, and restoration efforts).

Land use change results in the transformation of an ecosystem from one state to another state via a transition phase. This translation is hypothesized to confer impoverishment of ecological complexity, since belowground diversity declines during those transitions which consequently leads to a decline in aboveground biodiversity. Yet, transitions can also induce a restoration process and thereby increase the biodiversity of systems.

At this stage we lack sound understanding of multilevel interactions of managed systems, particularly relationships between aboveground and belowground processes. Thus, it is the goal of this Task to provide more reliable predictive information on the effects of management on the diversity and ecological complexity of different ecosystems, mostly for questions on the resilience and functional stability of ecosystems, i.e., tightly coupled above- and belowground systems.

Objectives

• to determine the effects of land use change on biodiversity and ecological complexity, with an emphasis on the interdependence of above and belowground biota
• to determine the effects of restorative land use change on the interdependence of above and below ground complexity for improved management plans

Implementation

In planning an extensive research programme it seems important to consider drivers causing changes in land use varying in respect to the intensity, extent, geometry and speed of change. The non-linear response to forcing of many of the ecosystems requires carefully planned sampling and analyses. Although the research areas are important world-wide the development of generic research protocols will be complicated by the system- and site-specificity of drivers of land use change. Nevertheless, networking of research groups focussing on similar ecosystems and land use types in geographic distinct regions should strongly be encouraged.

This Task will build as much as possible on ongoing research and existing projects and will establish strong links with current and future projects of Activity 3.4 on Effects of Global Change on Multi-species Agroecosystems. For this Task, the IGBP Terrestrial Transects is a useful approach, since it emphasizes integrated collaborative research efforts on global change issues, in particular, on the impacts of land-use change. The humid tropical systems in Central and South America, SE Asia and Central Africa, for instance, undergo intensive land-use change by successive conversion of forest land to agricultural production systems. The transect framework in this context refers to a conceptual transect drawn along an intensification gradient of land use from natural to highly intensified systems. Thus far, most of the work on the impacts of land-use change on the humid tropical regions has focussed on biogeochemical cycles. In this Task, however, the impact of land-use change on biodiversity and ecological complexity along these intensification transects will be addressed. The research on impacts of land-use change will be conducted at different spatial and temporal scales to allow predictions and extrapolations from the local scale to the patch, landscape, and regional scale. Other terrestrial transects addressing land-use change cover the semi-arid tropics and the mid-latitude semiarid region.

The work of this Task should also strongly benefit from Land Use/Cover Change (LUCC) initiatives where information on major human influences on land-cover changes in different geographical and historical contexts (obtained through remote sensing, case studies and modeling efforts) will be evaluated and examined for the consequences of those changes on biodiversity and ecological complexity of systems. For the implementation phase of this Task contacts should also be established with international networks focussing on research on sustainable land use. E.g., the facilities of the Consultive Group on International Agriculture Research (CGIAR) Ecoregional Center could provide ideal platforms for research on biodiversity issues of different farming systems and land-use programmes (e.g., Alternatives to Slash and Burn Programme). Links with the Tropical Soil Biology and Fertility Programme (TSBF) will be useful in fostering collaboration with the Soil Biodiversity Network focussing on the effects of agricultural intensification on soil biodiversity with implications for sustainability and productivity of agricultural systems. The Large Scale Biosphere- Atmosphere Experiment in Amazonia (LBA) is a multidisciplinary international initiative to build knowledge around the influence of land-use change on climatological, ecological, biogeochemical, and hydrological aspects of Amazonia, thus involvement with this programme would provides an excellent opportunity to complement research on land-use change related issues and biodiversity.

Proposed Timetable

• 1998 State-of-the-knowledge workshop and general planning workshop to define the scope of short-term and long-term activities, to set research priorities, and to establish links with different international groups and programmes for future network effort.
• 1999 Synthesis of first results; expansion of network to additional systems and sites and regions

Task 4.3.3: Modeling the Response of Ecological Complexity to Global Change
[Leader: Paul de Ruiter]

Previous and current ecological studies are directed towards particular aspects of global change, such as physiological and compositional responses (e.g., species composition and abundance) to elevated CO₂. These effects should be formalized into integrated models to predict more generally the response of ecological complexity to global change. Simple analytical models (e.g., radiation balance and gas emission models) and complex simulation models (e.g., global circulation models) predict changes in climate and atmospheric composition. Similarly, models need to be developed to formalize and predict likely, or at least plausible, overall effects of global change on ecological complexity.

The models developed in this Task will parallel those to be developed in Task 4.1.3. Simple models of ideas including rules of community assembly and disassembly will be extended to simulate system behaviour under change in climate and atmospheric composition. In addition, data-driven models will be developed in concert with the experimental work described in Task 4.3.1 and 4.3.2.

This Task will be carried out in close collaboration with the GCTE Focus 2 modeling effort, particularly at the patch and landscape scales (Activities 2.1 and 2.2). The latter will provide a general understanding of the impacts of global change on the composition and structure of terrestrial ecosystems, and the consequent feedbacks to climate and atmospheric composition.

Objectives

• To describe and predict the effects of global change on ecological complexity

Implementation

This Task will be implemented as two components, reflecting the two types of models to be developed.

The first component is based on theoretical models of species coexistence, which will be developed in Task 4.1.3. These models will then be coupled to simple ecosystem models (GCTE Tasks 1.4.1 and 2.1.3) in order to simulate effects of change in species composition on ecosystem processes (e.g., net primary productivity, nutrient cycling). These coupled models will be subjected to different external forces (i.e., changes in global change parameters such as CO₂ concentration and temperature) to predict the response of the system.

The second component focuses on the development of models, which will be based on actual data from experimental and observational studies of Task 4.3.1 and 4.3.2. These models will be obtained through experimental networks. Hence, this component will require close collaboration of modellers and experimentalists. Workshops for the implementation of experimental networks should also include these associated modeling activities. These models should also be evaluated for their generality and predictability.

Proposed Timetable

• 1998 Workshop to test existing and develop new models and to design and implement experimental networks as proposed in Task 4.3.1 and 4.3.2.
• 1999 Synthesis product

Activity 4.4: Implications of Changes in Ecological Complexity under Global Change Scenarios
[Leader: TBA]

Changes in the ecosystem complexity / functioning relationships due to global change could diminish the stability, resistance, and resilience of managed terrestrial ecosystems and thus may jeopardise important food and fibre sources, and could also diminish the ability of natural ecosystems both to provide natural resources (e.g., clean water) and to remove pollutants from the atmosphere. The goal of Activity 4.4 is to examine the societal implications of changes in ecological complexity based on the new understanding of the complexity/functioning relationship under global change derived from the work of the other three activities of Focus 4.

Activity 4.4 is organized around three Tasks. The first Task aims to generate scenarios of changes in ecological complexity at both the biome and global scales over a 50-100 year time frame. Such scenarios will provide a basis for a wide variety of impact studies. The second Task examines the implications of changes in ecological complexity on land use and resource management. It addresses two specific issues: (i) socioeconomic consequences based on case studies using cost-benefit analyses and risk assessment techniques; and (ii) development of strategies for biodiversity conservation in a land-cover matrix of varying ecological, economic, and sociocultural characteristics. The third Task explores the implications of changes in ecological complexity for pests and pathogens and their vectors, in particular, the ecological controls on their dynamics and distributions. Special emphasis will be placed on pests and pathogens that affect human health.

The research in Activity 4.4 will depend on collaboration with a large number of groups and other disciplines. These include other components of GCTE, DIVERSITAS, LUCC, IHDP, IUCN, and CITES. Analyses at the regional level will be carried out in collaboration with regional conservation authorities and other relevant groups.

Task 4.4.1: Scenarios of Change in Ecological Complexity
[Leader: Louis Lebel]

The IPCC scenarios of future changes in atmospheric CO₂ concentration and GCM scenarios of climate-change have proven valuable to assess potential impacts of global change on a variety of systems of importance for human wellbeing. Scenarios of land-use and land-cover change, now being developed within LUCC, will be especially useful for impact assessments dealing with terrestrial ecosystems. The accelerating changes in ecological complexity are themselves components of global change, and a set of scenarios of changes in ecological complexity is urgently needed to underpin the large number of studies on the implications of loss of biological diversity. The scenarios will parallel those on changes in atmospheric composition, climate, and land use. There will be "best case" and "worst case" scenarios, with a number of intermediate scenarios, including a "Business-As-Usual" case. The scenarios will encompass many important aspects of changes in ecological complexity, such as rates of extinction, biological invasions, and loss of connectivity through habitat fragmentation.

Objective

• To develop scenarios of changes in ecological complexity at regional and global scales on a 50-100 year time frame.

Implementation

These scenarios will be constructed at five-year intervals over a ten-year period, beginning in 1996 (i.e., scenarios generated in 1996, 2001, and 2006). The scenarios will include three sections: (1) principles on which the scenarios are constructed, such as theories on biological invasions and techniques for estimation of extinction rates; (2) global scenarios, as well as a biome-by-biome analysis; and (3) a general assessment of the implications of the various scenarios. Our current understanding of changes in ecological complexity will provide the basis for the initial set of scenarios, to be developed at a workshop in 1996 and published in both electronic and book forms. The future sets of scenarios will be constructed similarly, drawing on improved understanding arising from the work of Focus 4, DIVERSITAS, and other relevant studies, and will contribute to future IPCC scenarios of global change.

An interesting feature of the scenarios will be the capability to identify vulnerable areas around the world, i.e., areas where (i) relatively small changes in ecological complexity may lead to significant changes in ecosystem functioning, or where (ii) there is a potentially large loss of diversity from a diversity-rich system. This can be done by merging the biome-scale scenarios of complexity change with an estimation of the implications of such change for ecosystem functioning. The initial estimation of vulnerable areas will rely on the SCOPE synthesis of the ecosystem functioning of biodiversity while future projections will rely increasingly on the new understanding arising from the work of Focus 4.

Proposed Timetable

• 2001 Workshop to develop 2001 scenarios; publication of scenarios.
• 2006 Workshop to develop 2006 scenarios; publication of scenarios.

Task 4.4.2: Implications of Changes in Ecological Complexity for Land-Use and Resource Management
[Leader: TBA]

When selecting strategies for biodiversity management, policy makers must balance the competing needs and interests of multiple stakeholders. A balance must be set between groups that want to utilize bioresources for economic gain, groups that want to preserve the resources for future generations, and groups that justify their continued access to the resources based on traditional rights. Immediate local interests of these groups must be balanced against the perceived long-term regional and global interests of others.

Even when there is agreement on the specific objectives in biodiversity management, decision making is often complex, and even more difficult when financial resources are strained. Organizations responsible for preserving biodiversity often find themselves critically evaluating how to invest limited funds to make the greatest impact.

This Task will focus on two aspects of the implications of changes in ecological complexity for land use and resource management. One aspect of particular importance is the role of uncertainty and unpredictability associated with global change scenarios. Ecological complexity has often been demonstrated to be important in the risk avoidance/amelioration strategies of subsistence societies. Likewise, complexity plays a critical role in mediating unpredictable ecological events like pest outbreaks.

Though we have a general theoretical understanding of the role of ecological complexity in risk avoidance, and will be sharpening that understanding through the coordinated research in Focus 4, we must still translate that understanding for policy makers and resource managers. The socioeconomic consequences of reductions or increases in complexity in terms of risk avoidance must be defined. This component of Task 4.4.2 will seek to provide better understanding of the values and role of ecological complexity in human strategies for coping with uncertainties brought about by global change. The second implication concerns the direct management goal of conservation of ecological complexity. Habitat fragmentation and transformation are the two most direct threats to global biodiversity, but also indirect threats are of concern, for example, predicted changes in atmospheric composition and concomitant changes in climate.

As landscapes become more fragmented and transformed, the role of protected areas in conserving biodiversity becomes increasingly important. In the past, protected areas have usually been proclaimed in an ad hoc fashion, based on economic and social criteria, rather than ecological ones. Existing protected areas suffer many shortfalls: many are too small to protect viable populations (especially of animals with large home ranges); many are spatially isolated from one another, and from existing natural areas; and many are located in a transformed matrix. Existing protected areas that are not currently in a transformed matrix may well be so in the near future. If changes in climate and land use accelerate as predicted, then isolated protected areas will become meaningless for the long-term conservation of biodiversity. In order to allow biodiversity to respond to global change, movement corridors (of appropriate habitat), must be delineated and managed accordingly, on both local and continental scales. If corridors of natural habitat cannot be established among existing protected areas, the matrix around and among protected areas must be managed to allow movement. If new protected areas are to be proclaimed in the future, these must be located so as to maximize ecological attributes, as well as connectivity with existing protected areas. These new areas should also be placed in areas of abiotic and biotic gradients, to maximize the ability of biota to track changes in the environment.

The future degrees and types of land use transformations in any one region are difficult to predict, and conservation biologists and decision makers need to establish an interconnected web of protected areas on a global scale, if the conservation of biodiversity is to be maximized in the long term. The role of the matrix (i.e. areas outside of protected areas) will become increasingly important, and methods of appropriate land management for the matrix of land between protected areas have to be developed (e.g. ecotourism, hunting, education). These management methods will have to be appropriate for the social structure of the regions, and will have to be economically attractive to local communities and governments.

Objectives

• To analyse the socioeconomic consequences of changes in ecological complexity, including risk assessments and cost-benefit analyses, and to develop appropriate decision support methodologies.
• To assess implications of global change for biodiversity conservation in a land cover matrix with varying ecological, economic and sociocultural characteristics, and to develop appropriate decision support methodologies.

Implementation

The implementation of this research will require active participation from a range of disciplines in the natural and social sciences. GCTE's role is to provide expertise on the ecological aspects of the issues, and to work closely in collaborative teams with researchers who have skills in other areas required for the project. An especially important link is that to the Human Dimensions component of DIVERSITAS (Programme Element 10), which can provide much of the socioeconomic expertise required to carry out the impact studies.

The cost/benefit and risk assessment component of this Task will be based on a case study approach, with an initial review to determine the current state-of-the-science and to develop a work plan for a coordinated set of studies. For such studies, methods are needed for placing values on system components and synthesizing those values in ways that lead to transparency in the decision-making process and to consensus-building among stakeholders. These methods are currently emerging from a number of sectors, including ecological economics and sustainable-development fields, and will form a useful starting point for the work of this Task.

The first step in the conservation design component of this Task is to bring together a number of extant or developing global databases. These include global land cover and land use databases, with existing protected areas specified, and a database on existing untransformed land which is currently outside the network of nature reserves (e.g. private nature reserves, aboriginal lands, military testing grounds). The latter is not yet available in a consistent way at the global scale, so an early objective of this Task is to produce such a database. The linked databases of protected areas and untransformed lands will be a valuable tool and should be made freely available to decision makers in a user-friendly format so that scenario-planning is facilitated. The database will be updated at 3-5 year intervals.

The next, more difficult, step is to design methodologies for biodiversity conservation in a rapidly varying matrix of land cover types. Of particular importance is the nature of the ecological complexity in the matrix in which the reserves are embedded, and some scenarios of land cover transformations and modifications will be required. The interaction of such land cover changes with projected changes in climate and atmospheric composition should be emphasized, with a view to determining how these changes will affect the ecological complexity of the entire matrix. Other work within Focus 4 should provide valuable insights into how these changes in complexity will affect ecosystem functioning, and thus give estimates of the usefulness of the land cover matrix as a corridor or buffer to assist in biodiversity conservation.

An initial planning meeting, including conservation planners, reserve designers, ecologists, economists, politicians and agricultural experts, is required to develop a detailed implementation plan for this component of the Task. The ultimate goal will be to help managers determine (i) the location of new protected areas and corridors, and (ii) the management practices for the matrix of land between protected areas. A case study approach will be employed initially, and will hopefully lead to some general principles that can be applied more broadly.

The biodiversity conservation component of the Task should be implemented in close collaboration with GCTE's Activity 2.2 on global change impacts on landscape structure, Activity 3.4 on complex agroecosystems, LUCC. Further collaboration will be established with the Core Programme Element 5 of the DIVERSITAS operational plan on conservation, restoration, and sustainable use of biodiversity. In addition, collaboration with national and international (FAO, UNEP, UNESCO) programmes interested in biodiversity conservation will be pursued.

Proposed Timetable

• 1998 Initial workshop: review of existing work on cost/benefit and risk assessment analyses; initiate development of global database on untransformed land.
• 1999 Workshop to analyse land cover data and develop methodologies for case studies on conservation strategies for a matrix of varying land cover units; initiate case studies.
• 2000 Establish network for coordinated case studies on cost/benefit analyses and risk assessments.
• 2001 Workshops to synthesize results and review progress; update of global database of untransformed land.

[Focus 1] [Focus 2] [Focus 3]