Preface to the Princeton Landmarks in Biology Edition vii Preface xi Symbols Used xiii 1. The Importance of Islands 3 2. Area and Number of Speicies 8 3. Further Explanations of the Area-Diversity Pattern 19 4. The Strategy of Colonization 68 5. Invasibility and the Variable Niche 94 6. Stepping Stones and Biotic Exchange 123 7. Evolutionary Changes Following Colonization 145 8. Prospect 181 Glossary 185 References 193 Index 201

The Theory of Island Biogeography

All ecosystems are exposed to gradual changes in climate, nutrient loading, habitat fragmentation or biotic exploitation. Nature is usually assumed to respond to gradual change in a smooth way. However, studies on lakes, coral reefs, oceans, forests and arid lands have shown that smooth change can be interrupted by sudden drastic switches to a contrasting state. Although diverse events can trigger such shifts, recent studies show that a loss of resilience usually paves the way for a switch to an alternative state. This suggests that strategies for sustainable management of such ecosystems should focus on maintaining resilience.

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Catastrophic shifts in ecosystems.

Interactions between organisms are a major determinant of the distribution and abundance of species. Ecology textbooks (e.g., Ricklefs 1984, Krebs 1985, Begon et al. 1990) summarise these important interactions as intra- and interspecific competition for abiotic and biotic resources, predation, parasitism and mutualism. Conspicuously lacking from the list of key processes in most text books is the role that many organisms play in the creation, modification and maintenance of habitats. These activities do not involve direct trophic interactions between species, but they are nevertheless important and common. The ecological literature is rich in examples of habitat modification by organisms, some of which have been extensively studied (e.g. Thayer 1979, Naiman et al. 1988).

Organisms as ecosystem engineers

In 1997, the global value of ecosystem services was estimated to average $33 trillion/yr in 1995 $US ($46 trillion/yr in 2007 $US). In this paper, we provide an updated estimate based on updated unit ecosystem service values and land use change estimates between 1997 and 2011. We also address some of the critiques of the 1997 paper. Using the same methods as in the 1997 paper but with updated data, the estimate for the total global ecosystem services in 2011 is $125 trillion/yr (assuming updated unit values and changes to biome areas) and $145 trillion/yr (assuming only unit values changed), both in 2007 $US. From this we estimated the loss of eco-services from 1997 to 2011 due to land use change at $4.3–20.2 trillion/yr, depending on which unit values are used. Global estimates expressed in monetary accounting units, such as this, are useful to highlight the magnitude of eco-services, but have no specific decision-making context. However, the underlying data and models can be applied at multiple scales to assess changes resulting from various scenarios and policies. We emphasize that valuation of eco-services (in whatever units) is not the same as commodification or privatization. Many eco-services are best considered public goods or common pool resources, so conventional markets are often not the best institutional frameworks to manage them. However, these services must be (and are being) valued, and we need new, common asset institutions to better take these values into account.

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Changes in the global value of ecosystem services

▪ Abstract We review the evidence of regime shifts in terrestrial and aquatic environments in relation to resilience of complex adaptive ecosystems and the functional roles of biological diversity in this context. The evidence reveals that the likelihood of regime shifts may increase when humans reduce resilience by such actions as removing response diversity, removing whole functional groups of species, or removing whole trophic levels; impacting on ecosystems via emissions of waste and pollutants and climate change; and altering the magnitude, frequency, and duration of disturbance regimes. The combined and often synergistic effects of those pressures can make ecosystems more vulnerable to changes that previously could be absorbed. As a consequence, ecosystems may suddenly shift from desired to less desired states in their capacity to generate ecosystem services. Active adaptive management and governance of resilience will be required to sustain desired ecosystem states and transform degraded ecosystems...

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Regime Shifts, Resilience, and Biodiversity in Ecosystem Management

Elephants and Fire as Causes of Multiple Stable States in the Serengeti-Mara Woodlands

Various population parameters and physiological, behavioral, morphometric, meristic, calcareous, biochemical, and cytogenetic characters have been used to identify fish stocks. We define a stock as...

Stock Identification: Materials and Methods

EVIDENCE from ice cores1 indicates that concentrations of atmospheric carbon dioxide were lower by about 75 p.p.m. during the Last Glacial Maximum (LGM; ∼18,000 years ago) than during the present interglacial (10,000 years ago to the present). The causes of such large changes in atmospheric CO2 remain uncertain. Using a climate model, Prentice and Fung2 have estimated that there was approximately the same amount of carbon in vegetation and soils during the LGM as there was during the present (pre-industrial) interglacial. In contrast, we present here results based on palynological, pedological and sedimentological evidence which indicate that in fact the amount of carbon in vegetation, soils and peatlands may have been smaller during the LGM by ∼1.3x 1012 tonnes. Thus, organic carbon in vegetation and soils has more than doubled (from 0.96 to 2.3 x 1012 tonnes) since the LGM. Oceanic CO2 reservoirs seem to be the only possible source of this large quantity of carbon that has entered the terrestrial biosphere since the LGM (in addition to that which has entered the atmosphere to give the higher interglacial CO2 levels).

Increases in terrestrial carbon storage from the last glacial maximum to the present

Gross domestic product is a misleading measure of national success. Countries should act now to embrace new metrics, urge Robert Costanza and colleagues.

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Development: Time to leave GDP behind

We compare six marine ecosystems worldwide, using a network analysis of carbon flows for the Swartkops and Ems estuaries, Chesapeake Bay, the Baltic Sea and the Peruvian and Benguela upwelling regions. We find that there is an inverse correlation between the Finn Cycling Index (FCI) and the normalized internal ascendancy or system maturity (A $\_{\text{i}}$ :C $\_{\text{i}}$ ). We also show that there is a clear distinction between system maturity (A $\_{\text{i}}$ :C $\_{\text{i}}$ ) and the production: biomass (P:B) ratio; in upwelling systems the P:B and A $\_{\text{i}}$ :C $\_{\text{i}}$ ratios are both high, whereas in estuarine systems the P:B ratio is low. The P:B ratio thus cannot be used as an indicator of marine ecosystem evolution. Contrary to current views on ecosystems, the aggregate amount of cycling of materials, such as carbon, is not seen as an indication of system maturity but rather of stress. The reason that higher stressed systems are associated with a higher throughout or FCI could be because perturbations frequently impact higher-level species to a greater extent than the lower trophic components. Any release of standing biomass from these higher levels could therefore be taken up through increased recycling via short intense loops. Overall, we conclude that a network representation is a suitable methodology for inter-ecosystem comparisons.

Jacqueline McGlade

Papers

Elephants and Fire as Causes of Multiple Stable States in the Serengeti-Mara Woodlands

Stock Identification: Materials and Methods

Increases in terrestrial carbon storage from the last glacial maximum to the present

Development: Time to leave GDP behind

The Comparative Ecology of Six Marine Ecosystems