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We investigated relationships between light availability, diel acid fluctuation, and resource storage in the arborescent cactus Opuntia excelsa growing in western Mexico. We compared canopy and understory individuals from a deciduous forest as well as open-grown plants of the same approximate size as those in the understory. During the wet season light availability and daily fluctuations in titratable acidity (an index of carbon uptake) were lower in the understory than in unshaded habitats. In the dry season all plants had reduced levels of acid fluctuation, with the smallest individuals, regardless of habitat, showing the greatest reduction. These data suggest that light availability in the forest understory constrains carbon assimilation during the wet season, but that a factor associated with plant size, possibly water status, limits carbon gain during the dry season. Plants in all habitats remained physiologically active for at least five months into the dry season. We suggest that this was possible due to the maintenance of constant concentrations of water and nitrogen in the photosynthetically active chlorenchyma. Parenchyma in terminal cladodes showed a different seasonal pattern of resource storage; water content and nitrogen concentration were reduced from the wet to the dry season in the parenchyma. Using the parenchyma to supply photosynthetic tissues during times of reduced resource availability allows O. excelsa to assimilate carbon during times of the year when most other trees in the forest are leafless.

The effects of CO2 enrichment on plant growth, carbon and nitrogen acquisition and resource allocation were investigated in order to examine several hypotheses about the mechanisms that govern dry matter partitioning between shoots and roots. Wild radish plants (Raphanus sativus × raphanistrum) were grown for 25 d under three different atmospheric CO2 concentrations (200 ppm, 330 ppm and 600 ppm) with a stable hydroponic 150 μmol 1−1 nitrate supply. Radish biomass accumulation, photosynthetic rate, water use efficiency, nitrogen per unit leaf area, and starch and soluble sugar levels in leaves increased with increasing atmospheric CO2 concentration, whereas specific leaf area and nitrogen concentration of leaves significantly decreased. Despite substantial changes in radish growth, resource acquisition and resource partitioning, the rate at which leaves accumulated starch over the course of the light period and the partitioning of biomass between roots and shoots were not affected by CO2 treatment. This phenomenon was consistent with the hypothesis that root/shoot partitioning is related to the daily rate of starch accumulation by leaves during the photoperiod, but is inconsistent with hypotheses suggesting that root/shoot partitioning is controlled by some aspect of plant C/N balance.

Image: © Margarita Arianoutsou, 2013The community of ecologists studying Mediterranean-climate regions has lost a powerful and influential voice with the passing of Nikos Margaris, Professor at the...

Invasive species are defined by the Convention of Biological Diversity as “. . . those alien species which threaten ecosystems, habitats or species”. From biblical times biological invasions have been an ever-present threat to human life and livelihood. In many cases they have been shattering in their impact. They matter. The bubonic plague that swept through Europe in the fourteenth century, the Black Death, caused human populations to decline for more than a hundred years, and outbreaks of plague continued to take a toll until the eighteenth century. For 300 years it was “normal” for outbreaks to kill up to half the population of infected cities. Outbreaks in Venice in 1575–77 and 1630–31, for example, killed more than a third of the inhabitants, as did outbreaks in Seville in 1647–1652, London 1664–65, Vienna in 1679 and Marseilles in 1720–21. The first global pandemic, the “Spanish flu” of 1918–20 killed up to 100 million people, more than twice the number killed in the whole of the 1914– 1918 World War (McNeill 1977). More recently, HIV AIDS has killed around 22 million people worldwide since the 1980s. Writing at the end of the eighteenth century, Malthus observed that a combination of war and disease was the dominant check to population growth in most parts of the world

This chapter reviews the literature to understand the significance of making decisions about the prevention and/or control of invasive alien species (IAS) that ignore impacts on ecosystem services. It reports damage costs associated with IAS in monetary terms. The costs presented for various provisioning, regulating, and cultural services may be roughly comparable since most of the literature mostly clusters around the early 2000s. Whether damage costs of any magnitude will change the way IAS is managed will naturally depend on the benefits of the activities that lead to the introduction and spread of each species. Identifying potential damage costs and estimating their magnitude is a positive first step towards properly accounting for the full impact of IAS.

Invasive species control is a public good. Once provided, the benefits it offers in terms of enhanced protection of human, animal, and plant health, and the productivity of agriculture, forestry, aquaculture, and fisheries, are available to everyone. Like all public goods it will be undersupplied if left to the market. This makes it a collective responsibility — a legitimate role of government at many different scales. This role involves two different functions. One is the development of broad strategies and supporting institutions, statutes, regulations, or agreements for addressing the problem. A second function involves the implementation of that policy, and specifically the use of public resources to undertake all of the actions described in this volume: inspection and interception at the port of entry; sanitary and phytosanitary measures both along pathways; and in situ detection, eradication, and control of harmful species that have been introduced, established, and spread. This chapter considers both broad issues of policy and specific challenges to management.

[Figure][1] CREDIT: (LEFT) LINDA A. CICERO/STANFORD NEWS SERVICE; (RIGHT) IMPERIAL COLLEGE LONDON Global responses to the deterioration of biodiversity have been slow to emerge, but next month the United Nations (UN) Environment Programme hosts a meeting[*][2] in Nairobi, Kenya, to discuss the next steps in establishing a new science/policy interface for biodiversity and ecosystem services.The response in this arena still lags far behind negotiations related to climate change, but the meeting is a chance to boost international action, based on strong scientific evidence. An important motivation for creating this interface is meeting the goals of international multilateral agreements, including the Convention on Biological Diversity (CBD), the UN Convention to Combat Desertification, and the Ramsar Convention on Wetlands. Unlike the UN Framework Convention on Climate Change, which has the Intergovernmental Panel on Climate Change, these environmental conventions lack a pre-convention science assessment and have no provision for subsequent government-endorsed, independent science. The meeting in Nairobi will debate, among other issues, how best to make up for this crucial omission. Why is a robust biodiversity science/policy interface so important? The human population continues to mine the natural capital of Earth to support its growth, but the impact of this loss on human well-being is not widely understood in either public or policy spheres. Biodiversity is the building block of ecosystems that capture carbon and energy and cycle water and nutrients from the soil. These processes, and the structure of ecosystems that control them, benefit society with food, fuel, clean water, and climate regulation—so-called ecosystem services. The Millennium Ecosystem Assessment (MA), supported by UN agencies and nongovernmental organizations, concluded in 2005 that 60% of ecosystem services worldwide have become degraded, mostly in the past 50 years, primarily because of land-and ocean-use practices. ![Figure][1] CREDIT: STOCKBYTE/GETTY IMAGES We lack information on global and local trends in most biodiversity components at the level of genes, species, and ecosystems, as well as baselines and standards for their assessment. We will certainly miss the CBD's target for reducing the rate of biodiversity loss by 2010 and also miss the 2015 environmental targets within the UN Millennium Development Goals to improve health and livelihoods for the world's poorest and most vulnerable people. Changes in ecosystems and losses of biodiversity have continued to accelerate. Even the most conservative estimates suggest that an area of tropical rainforest greater than the size of California has been destroyed since 1992, mostly for food and fuel. Species extinction rates are at least 100 times those in pre-human times and are expected to increase. The situation is not hopeless. The MA outlined policy and management interventions at local to global scales that can reverse these trends, such as incentives for conservation based on payment for ecosystem services. Promising approaches to integrated land and sea use that will deliver multiple benefits require further scientific research. The challenges are complicated by continuing changes in climate, land use, human demography, and development, but the relevant science can be coordinated through international programs such as DIVERSITAS and the Earth System Science Partnership, and through international organizations such as the International Union for the Conservation of Nature. What is lacking is an effective dialogue between science-based information and relevant policy mechanisms to ramp up the speed and clarity of information flow. We urge that scientists not only continue to generate the science that underlies good policies and decisions, but also become informed on policy issues that relate to their expertise and are highlighted in published research. In each nation, scientists need to take the crucial step of ensuring that research information reaches the relevant decision-making levels of government. In October, the 100 or so participating countries should bring not only their best policy negotiators but also their best scientists to the Nairobi conference. A commitment to an intergovernmental science/policy platform on biodiversity and ecosystem services is possible only if scientists take a serious step forward and become centrally involved. [1]: pending:yes [2]: #fn-1

Although the effects of invasive alien species (IAS) on native species are well documented, the many ways in which such species impact ecosystem services are still emerging. Here we assess the costs and benefits of IAS for provisioning, regulating and cultural services, and illustrate the synergies and tradeoffs associated with these impacts using case studies that include South Africa, the Great Lakes and Hawaii. We identify services and interactions that are the least understood and propose a research and policy framework for filling the remaining knowledge gaps. Drawing on ecology and economics to incorporate the impacts of IAS on ecosystem services into decision making is key to restoring and sustaining those life-support services that nature provides and all organisms depend upon.

In virtually no area of the human enterprise is there more uncertainty than in matters of national defense. How well armed, trained, allied, clever, and persevering an aggressor might be is often uncertain. Moreover, the nature of an attack the direction of and with what weapons and strategy a strike might be made is normally deliberately concealed. In response to this great uncertainty, the United States has military bases around the world, nuclear submarines patrolling the remotest parts of the oceans, missiles poised to strike against any land or airborne target, and military satellites orbitin g the entire planet. Thousands of highly trained intelligence officers filter through the minutia of activities of perceived enemies and prepare elaborate contingency plans. The U.S. has carefully negotiated, verifiable international arms control treaties. Finally, it has developed the most advanced and sophisticated weapons and communications technology in the world to serve these functions. The cost of this form of military security currently consumes about a third of the United States’.federal budget. Indeed, the U.S. has spent in the last decade alone more than 1.5 trillion (1012> dollars to build up an arms apparatus against an enemy whose chance of attacking the U.S. in the last quarter century was never rated higher than about 3%. Now consider the stance of the current U.S. administration on global warming. Nearly every sector of the American economy could be adversely affected by climatic change, and nothing short of our national security and quality of life may be at stake. Most climatologists believe the chances of unprecedented climate change are at least 50%. Yet, offering as justification the uncertainty in timing and location of ‘the strike’, the Bush administration is doing virtually nothing to prepare a defense against this threat.

summary Whole plant acclimation to ozone exposure in growth-chamber cultivated radish (Raphanus sativus L. cv. Cherry Belle) was investigated. The primary goal was to separate developmental from physiological ozone acclimation processes. Plants were grown for 37 days at two different lengths of ozone exposure and a control treatment. After germination, seedlings were transplanted into controlled growth chambers and exposed to daytime (10 h) ozone (0.12 μl 1−1) either on the next day (continuous ozone treatment) or three days later (intermediate treatment) and compared to a control (average ambient ozone concentration (0.01–0.02 μml 1−1). Plants grown in ozone after transplanting accumulated considerably less biomass than the controls, but had higher dry weights than the intermediate treatment, implying an acclimation response. Photosynthetic capacity and nitrogen content of leaves decreased at high levels of ozone exposure resulting in an accelerated leaf senescence. No distinct leaf-level physiological acclimation to ozone exposure was seen based on gas exchange measurements. As an apparent compensatory response, plants exposed to ozone had higher leaf production rates than control plants, at the expense of root and hypocotyl growth. This developmental, whole-plant response appeared to be the most effective acclimation response to ozone exposure seen in radish. However, it did not fully compensate for the damage caused by ozone, since plants still showed considerable reductions in growth.

We studied the dynamics of a serpentine annual grassland in northern Cal- ifornia in relation to disturbance by pocket gophers (Thomomys bottae) and interannual variation in rainfall over the period 1982-1988. Mapping of gopher mound formation indicated that the probability that gophers would disturb any given area during the 6-yr study period had a near normal distribution with a peak at two disturbances during that period. Disturbance levels varied considerably from year to year and spatially, and thus the disturbance regime is complex. Exclosure experiments indicated that gopher disturbance had a significant effect on the abundances of many of the grassland annuals, perennial grasses, and cormaceous species. Aboveground herbivores had no detectable effects. Over the period of the study annual rainfall varied threshold and plant community dynamics were strongly affected by this. In particular, Plantago erecta decreased and Las- thenia californica increased in abundance with increasing rainfall. Abnormally high rainfall in 1982-1984 allowed the buildup of populations of Bromus mollis, the only nonnative species that invades the serpentine significantly. B. mollis was, however, subsequently virtually eliminated from the serpentine grassland by two consecutive years of severe drought. Invasion of B. mollis was found only on gopher mounds formed in 1983. In subsequent years recolonization of gopher mounds was predominantly by other species, in particular Lotus subpinnatus. Interannual variability in species abundances was most apparent on disturbed microsites. Our results provide a longer term perspective from which to view shorter term exper- imental and modelling work and highlight the need for long-term observations of ecological systems.

One of the many changes occurring in the biosphere due to human activities is the increase in the carbon dioxide concentration in the atmosphere. This change is due both to the burning of fossil fuels and to deforestation. We do not know how these changes are affecting terrestrial ecosystems. This ignorance is partly because we have relatively poor records of the functional and structural response of any ecosystem through time. More studies are required to be able to accurately assess the effects of carbon dioxide.

The biocultural conservation and research initiative of Omora Ethnobotanical Park and the UNESCO Cape Horn Biosphere Reserve was born in a remote part of South America and has rapidly expanded to attain regional, national, and international relevance. The park and the biosphere reserve, led by Ricardo Rozzi and his team, have made significant progress in demonstrating the way academic research supports local cultures, social processes, decision making, and conservation. It is a dynamic hive of investigators, artists, writers, students, volunteers, and friends, all exploring ways to better integrate academia and society. The initiative involves an informal consortium of institutions and organizations; in Chile, these include the University of Magallanes, the Omora Foundation, and the Institute of Ecology and Biodiversity, and in the United States, the University of North Texas, the Omora Sub-Antarctic Research Alliance, and the Center for Environmental Philosophy at the University of North Texas. The consortium intends to function as a hub through which other institutions and organizations can be involved in research, education, and biocultural conservation. The park constitutes one of three long-term socio-ecological research sites in Chile of the Institute of Ecology and Biodiversity.

Storage is a characteristic feature of most plants, particularly perennials, and the subject has been thoroughly reviewed according to its chemistry and physiology (9, 40, 59, 80, 133, 139). However, in ecology much of the information on storage is based on observation rather than experimentation, and experiments often fail to confirm common perceptions of the nature and dynamics of stored reserves. For example, clipping studies show that not all carbohydrates are available to the plant, even though they are considered to be stored reserves. In this review we suggest criteria for defining storage in ecological and eonomic contexts in order to examine the costs and benefits of storage. We then evaluate the evidence for, and ecological importance of, different types of storage. We discuss storage in relation to vegetative growth

SUMMARY Experiments were conducted to determine the impact of nitrogen and ozone (O3) stress on the growth of domestic radish Raphanus sativus L. cv. Cherry Belle. Plants were grown in field chambers with sub-, optimal and supra-optimal levels of nitrogenous fertilizer. Chamber air was either charcoal-filtered, or supplemented with one of two levels of O3. The highest O3 treatment resulted in significant reduction in weight of hypocotyls and roots while elevated nitrogen treatments resulted in increased weight of all plant parts. Ozone did not affect the weight of plant foliage at any nitrogen level. Plants grown with lower levels of nitrogen had less leaf biomass but the tissue accounted for a greater percentage total weight than did the foliage of higher nitrogen treatments. Relative growth rate of whole plants was not affected by O3 or nitrogen treatments reflecting compensation in response to both stresses. Ozone-induced depression in biomass was observed in O3-treated plants grown with higher nitrogen supply but not in those grown with limiting nitrogen. This observation could reflect compensation at the lower levels of nitrogen supply or inability to detect changes in biomass due to reduced weights of plants grown at the lowest nitrogen supply. The dry weight ratio of sink organs (hypocotyl plus root)/shoot was significantly correlated with the total non-structural carbohydrate (TNC) content of these organs, regardless of treatment. Initially, O3 induced a significant decrease and nitrogen an increase in percent TNC of sink organs. At later sampling times, plants adjusted to stress as effects on percent TNC were no longer evident.

In this study we surveyed branches of vines and trees to compare the ability of their wood to transport water by measuring their specific hydraulic conductivities; that is, we quantified the volume of water passing a given xylem transverse area per time for a known pressure gradient across excised twigs of vines and trees

Non-native annual grasses dominate most Californian mediterranean-cli- mate grasslands today. However, native Californian grassland flora persists in grasslands on serpentine-derived soils. We manipulated soil nutrient resources to explore the links between nutrient availability, plant productivity, and the relative abundances of native and non-native species in serpentine grassland. Factorial combinations of nitrogen, phos- phorus, and other components of a nutritionally complete formula were added to field plots over two growing seasons. Fertilization with nitrogen and phosphorus increased biomass of the resident vegetation substantially in the first season, and within two years allowed the invasion and dominance of non-native annual grasses in patches originally dominated by native annual forbs. Species richness declined with fertilization, as the increased biomass production by invaders sup- pressed some native forbs. Increased macronutrient availability can increase production on serpentine-derived soil, even when other serpentine characteristics (such as low Ca/Mg ratios and high heavy-metal concentrations) have not been mitigated. Observed changes in community structure and composition demonstrate that the invasibility of plant com- munities may be directly influenced by nutrient availability, independent of physical dis- turbance.

Although there is a strong relationship between genetically based variability of a given character and the potential for natural selection to act on that character, most studies of the effects of environmental factors on plants examine the mean responses of plants in a population and not the variability among plants in the population. Yet variability in the response among individuals to an environmental stress could foretell changes in a population that might not be evident from examination of mean responses. Here we report an analysis of data from several experiments on radish plants showing a significant relationship between the coefficient of variation for biomass production by radish plants and the concentration of SO2 at which these plants were fumigated. Increased variability as a result of SO2 exposure may have been due to genotypic differences in SO2 resistance among plants, suggesting a route by which the rapid selection of SO2 resistant plant populations may occur in habitats characterized by severe SO2 stress. Increased variability may have also been due to the effect of SO2 on processes controlling phenotypic plasticity of radish growth. Since SO2 affected variability without necessarily affecting mean plant growth, these results also show that examination of variability in the responses of plants to stresses may be equally or more biologically meaningful than sole examination of mean responses. Furthermore, these results show that care must be taken when constructing parametrically derived dose–response models for predicting the effect of SO2 on plants. If it is common for SO2 to increase the amount of variation in plant populations, then parametric statistical functions would be an inappropriate tool for predicting the effect of SO2 on plants.

Plants are finely tuned to the seasonality of their environment, and shifts in the timing of plant activity (i.e. phenology) provide some of the most compelling evidence that species and ecosystems are being influenced by global environmental change. Researchers across disciplines have observed shifting phenology at multiple scales, including earlier spring flowering in individual plants and an earlier spring green-up' of the land surface revealed in satellite images. Experimental and modeling approaches have sought to identify the mechanisms causing these shifts, as well as to make predictions regarding the consequences. Here, we discuss recent advances in several fields that have enabled scaling between species responses to recent climatic changes and shifts in ecosystem productivity, with implications for global carbon cycling.

This paper provides an original account of global land, water, and nitrogen use in support of industrialized livestock production and trade, with emphasis on two of the fastest-growing sectors, pork and poultry. Our analysis focuses on trade in feed and animal products, using a new model that calculates the amount of ‘‘virtual’’ nitrogen, water, and land used in production but not embedded in the product. We show how key meatimporting countries, such as Japan, benefit from ‘‘virtual’’ trade in land, water, and nitrogen, and how key meatexporting countries, such as Brazil, provide these resources without accounting for their true environmental cost. Results show that Japan’s pig and chicken meat imports embody the virtual equivalent of 50% of Japan’s total arable land, and half of Japan’s virtual nitrogen total is lost in the US. Trade links with China are responsible for 15% of the virtual nitrogen left behind in Brazil due to feed and meat exports, and 20% of Brazil’s area is used to grow soybean exports. The complexity of trade in meat, feed, water, and nitrogen is illustrated by the dual roles of the US and The Netherlands as both importers and exporters of meat. Mitigation of environmental damage from industrialized livestock production and trade depends on a combination of direct-pricing strategies, regulatory approaches, and use of best management practices. Our analysis indicates that increased water- and nitrogen-use efficiency and land conservation resulting from these measures could significantly reduce resource costs.

Selective consumption by herbivores influences the composition and structure of a range of plant communities. Anthropogenically driven global environmental changes, including increased atmospheric carbon dioxide (CO(2)), warming, increased precipitation, and increased N deposition, directly alter plant physiological properties, which may in turn modify herbivore consumption patterns. In this study, we tested the hypothesis that responses of annual grassland composition to global changes can be predicted exclusively from environmentally induced changes in the consumption patterns of a group of widespread herbivores, the terrestrial gastropods. This was done by: (1) assessing gastropod impacts on grassland composition under ambient conditions; (2) quantifying environmentally induced changes in gastropod feeding behaviour; (3) predicting how grassland composition would respond to global-change manipulations if influenced only by herbivore consumption preferences; and (4) comparing these predictions to observed responses of grassland community composition to simulated global changes. Gastropod herbivores consume nearly half of aboveground production in this system. Global changes induced species-specific changes in plant leaf characteristics, leading gastropods to alter the relative amounts of different plant types consumed. These changes in gastropod feeding preferences consistently explained global-change-induced responses of functional group abundance in an intact annual grassland exposed to simulated future environments. For four of the five global change scenarios, gastropod impacts explained > 50% of the quantitative changes, indicating that herbivore preferences can be a major driver of plant community responses to global changes.

Shifting plant phenology (i.e., timing of flowering and other developmental events) in recent decades establishes that species and ecosystems are already responding to global environmental change. Earlier flowering and an extended period of active plant growth across much of the northern hemisphere have been interpreted as responses to warming. However, several kinds of environmental change have the potential to influence the phenology of flowering and primary production. Here, we report shifts in phenology of flowering and canopy greenness (Normalized Difference Vegetation Index) in response to four experimentally simulated global changes: warming, elevated CO 2 , nitrogen (N) deposition, and increased precipitation. Consistent with previous observations, warming accelerated both flowering and greening of the canopy, but phenological responses to the other global change treatments were diverse. Elevated CO 2 and N addition delayed flowering in grasses, but slightly accelerated flowering in forbs. The opposing responses of these two important functional groups decreased their phenological complementarity and potentially increased competition for limiting soil resources. At the ecosystem level, timing of canopy greenness mirrored the flowering phenology of the grasses, which dominate primary production in this system. Elevated CO 2 delayed greening, whereas N addition dampened the acceleration of greening caused by warming. Increased precipitation had no consistent impacts on phenology. This diversity of phenological changes, between plant functional groups and in response to multiple environmental changes, helps explain the diversity in large-scale observations and indicates that changing temperature is only one of several factors reshaping the seasonality of ecosystem processes.

In the search for an integrated understanding of the relationships among productive activities, human well-being, and ecosystem functioning, we evaluated the services delivered by a tropical dry forest (TDF) ecosystem in the Chamela Region, on the Pacific Coast of Mexico. We synthesized information gathered for the past two decades as part of a long-term ecosystem research study and included social data collected in the past four years using the Millennium Ecosystem Assessment (MA) conceptual framework as a guide. Here we identify the four nested spatial scales at which information has been obtained and emphasize one of them through a basin conceptual model. We then articulate the biophysical and socio-economic constraints and drivers determining the delivery of ecosystem services in the Region. We describe the nine most important services, the stakeholders who benefit from those services, and their degree of awareness of such services. We characterize spatial and temporal patterns of the services' delivery as well as trade-offs among services and stakeholders. Finally, we contrast three alternative future scenarios on the delivery of ecosystem services and human well-being. Biophysical and socioeconomic features of the study site strongly influence humanâ'ecosystem interactions, the ecosystem services delivered, the possible future trajectories of the ecosystem, and the effect on human well-being. We discuss future research approaches that will set the basis for an integrated understanding of humanâ'ecosystem interactions and for constructing sustainable management strategies for the TDF.

Western Regional Center: National Institute for Global Environmental Change, University of California, Davis, California 95616, USA; Department of Wildlife, Fish and Conservation Biology, University of California, Davis, California 95616, USA; Department of Biological Sciences, Stanford University, Stanford, California 94305, USA; College of Forest Resources, University of Washington, Seattle, Washington 98195, USA; Southern Research Station, USDA Forest Service, Asheville, North Carolina 28802, USA; Department of Land, Air and Water Resources, University of California, Davis, California 95616, USA

Assessments must provide conditional predictions of the consequences of specific policy options, at well-defined spatial and temporal scales.

Since the Age of Exploration began, there has been a drastic breaching of biogeographic barriers that previously had isolated the continental biotas for millions of years. We explore the nature of these recent biotic exchanges and their consequences on evolutionary processes. The direct evidence of evolutionary consequences of the biotic rearrangements is of variable quality, but the results of trajectories are becoming clear as the number of studies increases. There are examples of invasive species altering the evolutionary pathway of native species by competitive exclusion, niche displacement, hybridization, introgression, predation, and ultimately extinction. Invaders themselves evolve in response to their interactions with natives, as well as in response to the new abiotic environment. Flexibility in behavior, and mutualistic interactions, can aid in the success of invaders in their new environment.

In this chapter we will review the current status of biological diversity in the mediterranean-climate regions of the world, making comparisons among them, as well as examining the threats to biological systems now and in the future. Mediterranean-type climates, which are characterized by a predominantly winter rainfall regime, exist in five regions of the world: parts of California, South Africa, Chile, southern Australia, and the Mediterranean basin. Even though all of these regions share broad climatic conditions and contain ecosystems that have similar structures and dynamics (Hobbs et al. 1995), each region has a unique history of human habitation and use. There is a long history of comparative biotic studies among these regions upon which we draw; however, there are no comparisons of the social drivers of land-use change among these areas. Our analyses are therefore less complete than we would like.

This chapter presents new and fundamental approaches to understanding the relationships between canopy distribution in time and space, and stand productivity. Among the many issues discussed, the relationship between allocation and productivity is given a special mention. Production is dependent on the proportion of dry matter allocated to a photosynthetic tissue, as well as the proportion of time this tissue was active in the plant (its phenology). Because of the analogy of “compound interest,” the gain in dry matter is higher for a photosynthetic tissue than for a nonphotosynthetic tissue when there are no environmental limitations. The ideas discussed in this chapter encourage the importance of phenology, growth, and allocation for terrestrial primary productivity. Background and examples for a subset of issues relevant to global change are also provided. The chapter highlights trees and forest ecosystems because these systems contain the predominant fraction of global terrestrial carbon stores in plants. The chapter concludes by highlighting several promising areas of research: extension of the present theory of the timing of allocation to include the phenology of belowground organs and reproduction; techniques for improving estimates of belowground productivity and patterns of global allocation above and belowground; and the use of remote sensing combined with modeling for estimating global phenology and productivity. It would be especially useful if one could relate these remotely sensed data of aboveground events to seasonal patterns of belowground production.

Publisher Summary Terrestrial ecosystems significantly contribute to the global carbon cycle. The chapter discusses that stocks and fluxes are increasingly altered by human activities, through changes in land use, in atmospheric composition, and in climate. This carbon sink results from an increase in global terrestrial net primary productivity (NPP). Thus, it is essential to know what the present value of global NPP is, and whether it will continue to increase to sustain an important terrestrial carbon sink. This chapter uses recent information provided in each of the biome-updated estimates of global values for NPP and phytomass. Finally, the current and expected changes in global NPP and net ecosystem productivity are discussed. The main source of uncertainty on global NPP lies in the biome area, and especially in forest area. Significant progress on biome maps is expected in the near future from the use of satellite data, once the classification done using such data can be given biome names that can receive a large acceptance. There is also some uncertainty on the current and future rates of change in NPP. Research on this aspect, at all scales, is developing fast. The chapter emphasizes on predicting more precisely the impact of human activities on NPP and on the carbon cycle in general. This information is crucial to design and implement sustainable development of human societies.

Publisher Summary This chapter probes the relationship between biodiversity and biogeochemistry. To do this an evolutionary as well as an ecological approach is adapted. The diversification of plants and animals has brought about a diversification of novel chemistry that in turn has had an impact on biogeochemistry. Even in fairly recent times new metabolic pathways have evolved in response to changing atmospheric conditions and have affected global biogeochemistry. With the development of the angiosperms and the coincident adaptive radiation of animals, novel and diverse chemical compounds have evolved. Many of these compounds have also had impacts on biogeochemistry, in some cases only locally, but in others more generally. From the research into the role of species richness in ecosystem functioning, including biogeochemistry, it is reported that richness can influence the carbon flux of ecosystems. The chapter concludes that a major biological revolution is in the process, which involves the mixing of biota formerly separated by oceans. Many of the new communities that are resulting have distinctive biogeochemical signatures.

The vast majority of nations have fallen far short of the Convention on Biological Diversity's (CBD's) 2010 target: to reduce the rate of loss of biodiversity ( 1 , 2 ). This prompted the CBD to develop a new plan of action, supported by 20 “SMART” (specific, measurable, ambitious, realistic, and time-bound) targets for 2020 ( 3 , 4 ). As the 10th Conference of the Parties (COP) of the CBD meets in Nagoya, Japan, to negotiate both plan and targets, it is critical that targets also be grounded in the real interests that people have in benefits provided by biodiversity. To evaluate targets on this basis, we use the ecosystem services framework developed by the Millennium Ecosystem Assessment (MA) ( 5 ). This framework balances resource conservation and use according to how societies value consumptive (e.g., food and fuel) and nonconsumptive (e.g., health and aesthetics) services provided by ecosystems.

Anne Larigauderie is Executive Director of DIVERSITAS, the international programme dedicated to biodiversity science of ICSU and UNESCO. She has a PhD in plant ecophysiology (Montpellier, 1985) and spent over 10 years studying the impact of increasing atmospheric CO2 and temperature on natural vegetation in different ecosystems. In 1999, she joined the International Council for Science, ICSU, as Environment Science Officer, in charge of ICSU’s portfolio of environmental programmes. At DIVERSITAS, since 2002, she is interested in strengthening the science–policy interface for biodiversity, and the role of scientists at international policy fora where more science is needed.

MESQUITE (Prosopis) trees growing in the rainless region of the Atacama Desert produce leaves that abscise and accumulate on a concrete-like carbonate surface, often attaining litter depths of 45 cm. The virtual lack of surface moisture inhibits leaf decomposi-tion, and prevents cycling of nitrogen, the mineral most often limiting plant growth. Leaves in the midpoint of a litter profile were aged to pre-bomb dates (older than 1950) and had both high nitrogen concentrations and a carbon to nitrogen ratio comparable to that of live leaves. The thick carbonate layer prevents root growth into the litter. Prosopis appear to persist by having roots that fix nitrogen in moist subsurface layers and by extracting water and other nutrients from ground water, allowing plants to persist in an ecosystem in which there is no nitrogen cycling.

Biological invasions are gaining attention as a major threat to biodiversity and an important element of global change. Recent research indicates that other components of global change, such as increases in nitrogen deposition and atmospheric CO2 concentration, favor groups of species that share certain physiological or life history traits. New evidence suggests that many invasive species share traits that will allow them to capitalize on the various elements of global change. Increases in the prevalence of some of these biological invaders would alter basic ecosystem properties in ways that feed back to affect many components of global change.