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

Humans are altering the composition of biological communities through a variety of activities that increase rates of species invasions and species extinctions, at all scales, from local to global. These changes in components of the Earth's biodiversity cause concern for ethical and aesthetic reasons, but they also have a strong potential to alter ecosystem properties and the goods and services they provide to humanity. Ecological experiments, observations, and theoretical developments show that ecosystem properties depend greatly on biodiversity in terms of the functional characteristics of organisms present in the ecosystem and the distribution and abundance of those organisms over space and time. Species effects act in concert with the effects of climate, resource availability, and disturbance regimes in influencing ecosystem properties. Human activities can modify all of the above factors; here we focus on modification of these biotic controls. The scientific community has come to a broad consensus on many aspects of the re- lationship between biodiversity and ecosystem functioning, including many points relevant to management of ecosystems. Further progress will require integration of knowledge about biotic and abiotic controls on ecosystem properties, how ecological communities are struc- tured, and the forces driving species extinctions and invasions. To strengthen links to policy and management, we also need to integrate our ecological knowledge with understanding of the social and economic constraints of potential management practices. Understanding this complexity, while taking strong steps to minimize current losses of species, is necessary for responsible management of Earth's ecosystems and the diverse biota they contain.

/pdf/effects-of-biodiversity-on-ecosystem-functioning-a-consensus-13j8vabcus.pdf

Effects of biodiversity on ecosystem functioning: a consensus of current knowledge

A doubling in global food demand projected for the next 50 years poses huge challenges for the sustainability both of food production and of terrestrial and aquatic ecosystems and the services they provide to society. Agriculturalists are the principal managers of global useable lands and will shape, perhaps irreversibly, the surface of the Earth in the coming decades. New incentives and policies for ensuring the sustainability of agriculture and ecosystem services will be crucial if we are to meet the demands of improving yields without compromising environmental integrity or public health.

/pdf/agricultural-sustainability-and-intensive-production-1h98l920tu.pdf

Agricultural sustainability and intensive production practices

Bringing together leaf trait data spanning 2,548 species and 175 sites we describe, for the first time at global scale, a universal spectrum of leaf economics consisting of key chemical, structural and physiological properties. The spectrum runs from quick to slow return on investments of nutrients and dry mass in leaves, and operates largely independently of growth form, plant functional type or biome. Categories along the spectrum would, in general, describe leaf economic variation at the global scale better than plant functional types, because functional types overlap substantially in their leaf traits. Overall, modulation of leaf traits and trait relationships by climate is surprisingly modest, although some striking and significant patterns can be seen. Reliable quantification of the leaf economics spectrum and its interaction with climate will prove valuable for modelling nutrient fluxes and vegetation boundaries under changing land-use and climate.

/pdf/the-worldwide-leaf-economics-spectrum-1uikdmil76.pdf

The worldwide leaf economics spectrum

We discuss the physical and enzymatic bases of carbone isotope discrimination during photosynthesis, noting how knowledge of discrimination can be used to provide additional insight into photosynthetic metabolism and the environmental influences on that process

Carbon Isotope Discrimination and Photosynthesis

The Kyoto protocol aims to reduce carbon emissions into the atmosphere. Part of the strategy is the active management of terrestrial carbon sinks, principally through afforestation and reforestation. In their Perspective,
 Schulze
 et al.
 argue that the preservation of old-growth forests may have a larger positive effect on the carbon cycle than promotion of regrowth.

Managing forests after Kyoto

Mutants and transformants of tobacco (Nicotiania tabacum L. cv Gatersleben 1) with decreased expression of nitrate reductase have been used to investigate whether nitrate accumulation in the shoot acts as a signal to alter allocation between shoot and root growth. (a) Transformants with very low (1–3% of wild-type levels) nitrate reductase activity had growth rates, and protein, amino acid and glutamine levels similar to or slightly lower than a nitrate-limited wild-type, but accumulated large amounts of nitrate. These plants should resemble a nitrate-limited wild-type, except in responses where nitrate acts as a signal. (b) Whereas the shoot:root ratio decreases from about 3.5 in a well-fertilized wild-type to about 2 in a nitrate-limited wild-type, the transformants had a very high shoot:root ratio (8–10) when they were grown on high nitrate. When they were grown on lower nitrate concentrations their shoot:root ratio declined progressively to a value similar to that in nitrate-limited wild-types. Mutants with a moderate (30–50%) decrease of nitrate reductase also had a small but highly significant increase of their shoot:root ratio, compared to the wild-type. The increased shoot:root ratio in the mutants and transformants was due to a stimulation of shoot growth and an inhibition of root growth. (c) There was a highly significant correlation between leaf nitrate content and the shoot:root ratio for eight genotypes growing at a wide range of nitrate supply. (d) A similar increase of the shoot:root ratio in nitrate reductase-deficient plants, and correlation between leaf nitrate content and the shoot:root ratio, was found in plants growing on ammonium nitrate. (f) Split-root experiments, in which the transformants were grown with part of their root system in high nitrate and the other part in low nitrate, showed that root growth is inhibited by the accumulation of nitrate in the shoot. High concentrations of nitrate in the rooting medium actually stimulate local root growth. (g) The inhibition of root growth in the transformants was relieved when the transformants were grown on limiting phosphate, even though the nitrate content of the root remained high. This shows that the nitrate-dependent changes in allocation can be overridden by other signals that increase allocation to root growth. (h) The reasons for the changed allocation were investigated in transformants growing normally, and in split-root culture. Accumulation of nitrate in the shoot did not lead to decreased levels of amino acids or protein in the roots. However, it did lead to a strong inhibition of starch synthesis and turnover in the leaves, and to decreased levels of sugars in the root. The rate of root growth was correlated with the root sugar content. It is concluded that these changes of carbon allocation could contribute to the changes in shoot and root growth.

https://onlinelibrary.wiley.com/doi/pdf/10.1046/j.1365-313X.1997.11040671.x

Accumulation of nitrate in the shoot acts as a signal to regulate shoot‐root allocation in tobacco†

A Introduction to the European Transect.- 1 The Carbon and Nitrogen Cycle of Forest Ecosystems.- 1.1 Introduction.- 1.2 The Carbon and Nitrogen Cycles.- 1.3 The NIPHYS/CANIF Project.- 1.4 Experimental Design.- 1.5 Conclusions.- References.- 2 Experimental Sites in the NIPHYS/CANIF Project.- 2.1 Site Description. The NIPHYS/CANIF Transect.- 2.2 Soil Characteristics.- 2.3 Ecosystem C and N Pools.- 2.4 Database.- 2.5 Conclusions.- References.- B Plant-Related Processes.- 3 Tree Biomass, Growth and Nutrient Pools.- 3.1 Introduction.- 3.2 Experimental Background.- 3.3 Biomass.- 3.4 Forest Productivity.- 3.5 Carbon and Nutrient Pools.- 3.6 Allometric and Functional Relations.- 3.7 Conclusion.- References.- 4 Linking Plant Nutrition and Ecosystem Processes.- 4.1 Introduction.- 4.2 Experimental Approach.- 4.3 Nutrient Concentrations.- 4.4 Nutrient Contents.- 4.5 Nitrogen Partitioning in Different Tree Compartments.- 4.6 Ecosystem C and N Pools.- 4.7 Conclusions.- References.- 5 Root Growth and Response to Nitrogen.- 5.1 Introduction.- 5.2 Approaches to the Study of Root Growth.- 5.3 Root Growth Measurements Obtained by Soil Coring.- 5.4 Root Growth Measurements Obtained by Root Windows.- 5.5 Root Growth Measurements Obtained by In-Growth Cores.- 5.6 Root Growth at Different European Forest Sites.- 5.7 Conclusion.- References.- 6 Nitrogen Uptake Processes in Roots and Mycorrhizas.- 6.1 Introduction.- 6.2 Approaches to Study Different Aspects of the N Uptake Process.- 6.3 Studies with Excised Roots and Mycorrhizas.- 6.4 Field-Based Experiments.- 6.5 Conclusions.- References.- 7 The Fate of 15N-Labelled Nitrogen Inputs to Coniferous and Broadleaf Forests.- 7.1 Introduction.- 7.2 Sites of Investigation.- 7.3 Approaches to Study the Fate of 15N-Labelled Nitrogen Inputs.- 7.4 N Release and Tree Uptake from 15N-Labelled Decomposing Litter in a Beech Forest in Aubure.- 7.5 Ecosystem Partitioning of 15N-Labelled Ammonium and Nitrate on the Sites in the Fichtelgebirge and Steigerwald.- 7.6 Conclusion.- References.- 8 Canopy Uptake and Utilization of Atmospheric Pollutant Nitrogen.- 8.1 Introduction.- 8.2 Atmospheric Nitrogen Pollutants.- 8.3 Pathways for Canopy Uptake of Nitrogen.- 8.4 Approaches to the Determination of Canopy Uptake of Nitrogen.- 8.5 Review of Research.- 8.6 Role in the Critical Load.- 8.7 Ecophysiological Consequences of Canopy N Uptake.- 8.8 Conclusions.- 8.9 Way Forward.- 8.10 Policy Implications.- References.- 9 Biotic and Abiotic Controls Over Ecosystem Cycling of Stable Natural Nitrogen, Carbon and Sulphur Isotopes.- 9.1 Introduction.- 9.2 Approaches to the Study of Stable Isotopes in the Field.- 9.3 ?15N of Ammonium and Nitrate in Wet Deposition.- 9.4 Stable Isotope Signatures in Different Ecosystem Compartments.- 9.5 ?15N Signatures as Indicators of N Saturation in Forest Ecosystems.- 9.6 Conclusion.- References.- C Heterotrophic Processes.- 10 Soil Respiration in Beech and Spruce Forests in Europe: Trends, Controlling Factors, Annual Budgets and Implications for the Ecosystem Carbon Balance.- 10.1 Introduction.- 10.2 Approaches to Measuring Soil Respiration.- 10.3 Daily and Seasonal Trends in Soil Respiration and Climatic Variables.- 10.4 Factors Controlling Soil Respiration.- 10.5 Comparison of Chamber Measurements with the Eddy Covariance Measurements Below the Canopy.- 10.6 Annual Budgets of Soil Respiration.- 10.7 Conclusion.- References.- 11 Annual Carbon and Nitrogen Fluxes in Soils Along the European Forest Transect, Determined Using the 14C-Bomb.- 11.1 Introduction.- 11.2 Forests, Sampling Procedure and Analysis.- 11.3 Model Description.- 11.4 Estimations of C and N Pools and Fluxes.- 11.5 Pools and Distribution of Carbon and Nitrogen in Soil Profiles.- 11.6 Variations in the Carbon Age and Mean Residence Times (MRTs).- 11.7 Annual Carbon and Nitrogen Fluxes.- 11.8 General Discussion.- 11.9 Conclusion.- References.- 12 Carbon Mineralisation in European Forest Soils.- 12.1 Introduction.- 12.2 Experimental Background.- 12.3 C Mineralisation in the North-South Transect.- 12.4 Long-Term Fertilisation Experiments.- 12.5 Mean Residence Time.- 12.6 Comparison of Intact and Sieved Soil Cores.- 12.7 Conclusion.- References.- 13 Litter Decomposition.- 13.1 Introduction.- 13.2 Factors Affecting the Decomposition Process.- 13.3 Enzymatic Activity.- 13.4 Nitrogen Dynamics in Decomposing Litter.- 13.5 Decomposition Studies in Europe: from DECO, VAMOS, MICS to CANIF.- 13.6 Decomposition Studies Within a Latitudinal Transect of European Beech Forests.- 13.7 Conclusion.- References.- 14 Soil Nitrogen Turnover - Mineralisation, Nitrification and Denitrification in European Forest Soils.- 14.1 Background and Aim of the Study.- 14.2 Methods Used to Study N Turnover.- 14.3 Net N Mineralisation Based on Laboratory Studies.- 14.4 Net Nitrification Based on Laboratory Studies.- 14.5 Manipulation of pH, N Availability and Nitrifier Density in the Laboratory.- 14.6 Autotrophic Versus Heterotrophic Nitrification.- 14.7 Net N Mineralisation and Nitrification in N-Fertilisation Experiments.- 14.8 Comparison of N Turnover in Similar Soils at Different Climate.- 14.9 Comparison of N Turnover in Sieved and Intact Soil Cores.- 14.10 In Situ Mineralisation Studies at Aubure.- 14.11 Comparison of in Situ and Laboratory-Based Mineralisation Studies.- 14.12 Denitrification.- 14.13 Final Discussion.- 14.14 Conclusions.- References.- 15 Nitrogen and Carbon Interactions of Forest Soil Water.- 15.1 Introduction.- 15.2 Approaches to Studying the Forest Soil Waters.- 15.3 Soil Water Concentrations of Nitrogen and Carbon.- 15.4 Correlation Between Dissolved Organic Nitrogen and Carbon.- 15.5 Conclusions.- References.- D Diversity-Related Processes.- 16 Fungal Diversity in Ectomyccorhizal Communities of Norway Spruce [Picea abies (L.) Karst.] and Beech (Fagus sylvatica L.) Along North-South Transects in Europe.- 16.1 Introduction.- 16.2 Analysis of Ectomycorrhizal Community Structure and Diversity.- 16.3 ECM Communities of Spruce Forests.- 16.4 ECM Communities of Beech Forests.- 16.5 Genetic Diversity Within a Population of Laccarina amethystina.- 16.6 Isolation and Growth of ECM Fungal Isolates on an Organic N Source.- 16.7 Comparative Evaluation of Ectomycorrhizal Diversity.- 16.8 Conclusion.- References.- 17 Diversity and Role of the Decomposer Food Web.- 17.1 Introduction.- 17.2 Approaches to Investigating Decomposer Communities.- 17.3 The Microflora.- 17.4 The Soil Fauna.- 17.5 Contribution of the Decomposer Food Web to C and N Flows.- 17.6 Conclusions.- References.- 18 Diversity and Role of Microorganisms.- 18.1 Introduction and Background.- 18.2 Experimental Background.- 18.3 Community of Microfungi in Beech Forests.- 18.4 Functional Diversity of Bacteria in the Litter of Coniferous Forests.- 18.5 Conclusion.- References.- E Integration.- 19 Spatial Variability and Long-Term Trends in Mass Balance of Nand S in Central European Forested Catchments.- 19.1 Introduction.- 19.2 Approaches to Studying Long-Term Changes in Watersheds.- 19.3 Temporal Variations and Trends.- 19.4 Budgets.- 19.5 Biological Cycling of Sulphur.- 19.6 Conclusion.- References.- 20 Model Analysis of Carbon and Nitrogen Cycling in Picea and Fagus Forests.- 20.1 Introduction.- 20.2 Model Description.- 20.3 Input Data and Parameter Values.- 20.4 Model Calibration and Comparison with Measured Data.- 20.5 Model Analysis.- 20.6 Conclusions.- References.- 21 Interactions Between the Carbon and Nitrogen Cycle and the Role of Biodiversity: A Synopsis of a Study Along a North-South Transect Through Europe.- 21.1 Introduction.- 21.2 Change of Ecosystem Processes Along the European Transect.- 21.3 What Limits the C and N Fluxes in These Forest Ecosystems?.- 21.4 What Are Net Ecosystem Productivity (NEP) and Net Biome Productivity (NBP) and How Do They Relate to Ecosystem Parameters?.- 21.5 Are There Thresholds and Non-Linearities?.- 21.6 What Role Does Biodiversity Play in Ecosystem Processes?.- 21.7 Conclusions.- References.- Species Index.

/pdf/carbon-and-nitrogen-cycling-in-european-forest-ecosystems-276es1gu0j.pdf

Carbon and nitrogen cycling in European forest ecosystems

Large areas of the lower epidermis of full-grown leaves of Polypodium vulgare (and Valerianella locusta) are normally separated from the mesophyll by an extensive subepidermal airspace. Epidermal stripes were prepared for experiments to simulate these conditions in order to investigate stomatal reactions. They were placed with their inner surface in contact with an airspace of uniformly high humidity. The outer surface was treated with air of varying degrees of humidity. The stomatal reactions were observed by microscope and the opening of the guard cells determined photographically. Treatment of the outer side of the epidermis with dry air led to a rapid closing of the stomata, whilst moist air caused opening. This induction of opening and closing movements could be repeated up to 15 times with the same stoma by changing the degree of humidity. Neighbouring groups of stomata showed different apertures according to their individual humidity conditions. The degree of aperture of the stomata depended on the water potential of the ambient air and also on the humidity conditions in the subepidermal airspace. The cause of this stomatal behaviour could lie in the “peristomatal transpiration”. In this way, the guard cells are able to function as “humidity sensors” which “measure” the difference in water potential inside and outside the leaf. Their aperture thus is controlled by their individual transpiration conditions. This controlling mechanism could be very important for the water economy of plants. They would appear to be able to reduce their transpiration through an increase in diffusion resistance of the stomata during decreasing humidity in the ambient air, without changing the water status of the whole leaf.

Responses of stomata to changes in humidity.

ATTEMPTS to understand how atmospheric nitrogen deposition affects forest ecosystems1'2 have been hampered by the lack of a direct method to trace the fate of the deposited nitrogen. Nitrate originating in the atmosphere has natural abundances of nitrogen and oxygen isotopes that differ measurably from those of soil nitrate3. Here we present an analysis of the isotope ratios of nitrate in spring waters from eight forested watersheds, ranging from apparently healthy spruce plantations to those in decline owing to acidification. We find that for the healthy, slightly declining and limed sites, only 16–30% of the nitrate in spring water originates directly from the atmosphere without being processed in the soil, whereas for more severely damaged sites almost all of the atmos-pheric nitrate finds its way directly into the spring water. This suggests that acid-induced forest decline significantly inhibits nitrate consumption by soil microorganisms and trees, and that liming to ameliorate soil acidification restores the consumption of atmospheric nitrate. Nevertheless, in limed ecosystems total nitrate output remains high because of internal nitrate production by the ecosystem.

Ernst Detlef Schulze

Papers

Managing forests after Kyoto

Accumulation of nitrate in the shoot acts as a signal to regulate shoot‐root allocation in tobacco†

Carbon and nitrogen cycling in European forest ecosystems

Responses of stomata to changes in humidity.

Effects of forest decline on uptake and leaching of deposited nitrate determined from 15 N and 18 O measurements