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.

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

Soil amendment with biochar is evaluated globally as a means to improve soil fertility and to mitigate climate change. However, the effects of biochar on soil biota have received much less attention than its effects on soil chemical properties. A review of the literature reveals a significant number of early studies on biochar-type materials as soil amendments either for managing pathogens, as inoculant carriers or for manipulative experiments to sorb signaling compounds or toxins. However, no studies exist in the soil biologyliterature that recognize the observed largevariations ofbiochar physico-chemical properties. This shortcoming has hampered insight into mechanisms by which biochar influences soil microorganisms, fauna and plant roots. Additional factors limiting meaningful interpretation of many datasets are the clearly demonstrated sorption properties that interfere with standard extraction procedures for soil microbial biomass or enzyme assays, and the confounding effects of varying amounts of minerals. In most studies, microbial biomass has been found to increase as a result of biochar additions, with significant changes in microbial community composition and enzyme activities that may explain biogeochemical effects of biochar on element cycles, plant pathogens, and crop growth. Yet, very little is known about the mechanisms through which biochar affects microbial abundance and community composition. The effects of biochar on soil fauna are even less understood than its effects on microorganisms, apart from several notable studies on earthworms. It is clear, however, that sorption phenomena, pH and physical properties of biochars such as pore structure, surface area and mineral matter play important roles in determining how different biochars affect soil biota. Observations on microbial dynamics lead to the conclusion of a possible improved resource use due to co-location of various resources in and around biochars. Sorption and therebyinactivation of growth-inhibiting substances likelyplaysa rolefor increased abundance of soil biota. No evidence exists so far for direct negative effects of biochars on plant roots. Occasionally observed decreases in abundance of mycorrhizal fungi are likely caused by concomitant increases in nutrient availability,reducing theneedfor symbionts.Inthe shortterm,therelease ofavarietyoforganic molecules from fresh biochar may in some cases be responsible for increases or decreases in abundance and activity of soil biota. A road map for future biochar research must include a systematic appreciation of different biochar-types and basic manipulative experiments that unambiguously identify the interactions between biochar and soil biota.

http://www.css.cornell.edu/faculty/lehmann/pictures/publ/SoilBiolBiochem%2043,%201812–1836,%202011%20Lehmann.pdf

Biochar effects on soil biota – A review

I. the origin of species by means of natural selection

The links between plant diversity and ecosystem functioning remain highly controversial. There is a growing consensus, however, that functional diversity, or the value and range of species traits, rather than species numbers per se, strongly determines ecosystem functioning. Despite its importance, and the fact that species diversity is often an inadequate surrogate, functional diversity has been studied in relatively few cases. Approaches based on species richness on the one hand, and on functional traits and types on the other, have been extremely productive in recent years, but attempts to connect their findings have been rare. Crossfertilization between these two approaches is a promising way of gaining mechanistic insight into the links between plant diversity and ecosystem processes and contributing to practical management for the conservation of diversity and ecosystem services.

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Vive la différence: plant functional diversity matters to ecosystem processes

Assistant professor in the Department of Biology at Western Washington University, Bellingham, Washington 98225-9160 10: Professor at the Laboratoire d'Ecologie de Sols Tropicaux, ORSTOM/Universite Paris VI, 32 Avenue Henri Varagnat, 93143 Bondy, France 11: Senior scientist at the Centre for Terrestrial Ecology, Netherlands Institute of Ecology, 6666 ZG Heteren, Netherlands Utrecht, Netherlands 12: Professor at the Department of Environmental Studies, University of Utrecht, Utrecht, Netherlands 13: Professor at the Institute of Soil Biology, Academy of Sciences of the Czech Republic, Na sadkach 7, 370 05 Ceske Budejovice, Czech Republic 14: Professor at the Department of Environmental Science, Policy,and Management, University of California, Berkeley, California 94720-3110 15: Professor at the Center for Microbial Ecology, Michigan State University, 540 Plant and Soil Science Building, East Lansing, Michigan 48824-1325 16: Professor at the Department of Animal Ecology, Justus Liebig University of Giessen, Heinrich-Buff-Ring 26-32 (IFZ), D-35392 Giessen, Germany 2: Professor at the Queen Mary and Westfield College, School of Biological Sciences, University of London, London E1 4NS, United Kingdom 3: Research professor and the director of the Centre for Agri-Environmental Research, Department of Agriculture, University of Reading, Earley Gate, Reading RG6 6AT, United Kingdom 4: Professor of Soil Biology and Biological Soil Quality and director of the Department of Environmental Sciences, Wageningen University, 6700 EC Wageningen, Netherlands 5: Professor at the Centre for Biodiversity and Bioresources, School of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia 6: Chair, SCOPE Committee on Soil and Sediment Biodiversity and Ecosystem Functioning, and professor and director, Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, Colorado 80523 7: Scientist at Landcare Research, Lincoln, New Zealand 8: Research professor in the Institute of Ecology at the University of Georgia, 102 Ecology Annex, Athens, Georgia 30602-2360 9: Professor at the Department of Soil Science and Agricultural Engineering, University of Zimbabwe, Mount Pleasant, Harare, Zimbabwe

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Interactions between Aboveground and Belowground Biodiversity in Terrestrial Ecosystems: Patterns, Mechanisms, and Feedbacks

We review the current knowledge on biodiversity in soils, its role in ecosystem processes, its importance for human purposes, and its resilience against stress and disturbance. The number of existing species is vastly higher than the number described, even in the macroscopically visible taxa, and biogeographical syntheses are largely lacking. A major effort in taxonomy and the training of a new generation of systematists is imperative. This effort has to be focussed on the groups of soil organisms that, to the best of our knowledge, play key roles in ecosystem functioning. To identify such groups, spheres of influence (SOI) of soil biota - such as the root biota, the shredders of organic matter and the soil bioturbators - are recognized that presumably control ecosystem processes, for example, through interactions with plants. Within those SOI, functional groups of soil organisms are recognized. Research questions of the highest urgency are the assignment of species to functional groups and determining the redundancy of species within functional groups. These priorities follow from the need to address the extent of any loss of functioning in soils, associated with intensive agriculture, forest disturbance, pollution of the environment, and global environmental change. The soil biota considered at present to be most at risk are species-poor functional groups among macrofaunal shredders of organic matter, bioturbators of soil, specialized bacteria like nitrifiers and nitrogen fixers, and fungiforming mycorrhizas. An experimental approach in addressing these research priorities is needed, using longterm and large-scale field experiments and modern methods of geostatistics and geographic information systems. (Less)

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Biodiversity and ecosystem functioning in soil

1. Increased agricultural intensification has led to well-documented declines in the fauna and flora associated with intensive grasslands in the UK. We aimed to quantify the effectiveness of different field margin management strategies for putting bumblebee and butterfly biodiversity back into intensive grasslands.

2. Using four intensive livestock farms in south-west England, we manipulated conventional management practices (addition of inorganic fertilizer, cutting frequency and height, and aftermath grazing) to generate seven grass-based treatments along a gradient of decreasing management intensity. We also tested two more interventionist treatments which introduced sown components into the sward: (i) a cereal, grass and legume mix, and (ii) a diverse conservation mix with kale, mixed cereals, linseed and legumes. These crop mixtures were intended to provide forage and structural resources for pollinators but were not intended to have agronomic value as livestock feed. Using a replicated block design, we monitored bumblebee and butterfly responses in 27 plots (10 × 50 m) in each farm from 2003 to 2006.

3. Bumblebees were most abundant, species-rich and diverse in the sown treatments and virtually absent from the grass-based treatments. The diverse conservation mix treatment supported larger and more diverse bumblebee assemblages than the cereal, grass and legume mix treatment. The sown treatments, and the most extensively managed grass-based treatments, had the highest abundance, species richness and diversity of adult butterflies, whereas butterfly larvae were only found in the grass-based treatments.

4. Bumblebee and butterfly assemblage structure was driven by floral abundance, floral richness, the availability of nectar resources, and sward structure. Only vegetation cover was correlated with butterfly larval abundance.

5. Synthesis and applications. This study has identified management options in the margins of intensive grasslands which can enhance bumblebee and butterfly biodiversity. Extensification of conventional grass management by stopping fertilization, reducing cutting frequency and not grazing, benefits butterflies. However, to enhance bumblebees requires a more interventionist approach in the form of sowing flower-rich habitat. Both approaches are potentially suitable for adoption in agri-environment schemes in the UK and Europe

https://besjournals.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2664.2009.01609.x

Enhancing pollinator biodiversity in intensive grasslands

Insect-plant interactions at the community level are discussed in terms of the life-cycle strategies of the insects at different stages in plant succession and the effects of early colonising insect herbivores on the development of the plant community. Insect life-cycle strategies are influenced by habitat permanence, habitat complexity and resource availability and diversity. These factors increase as plant succession proceeds. The life-cycle strategies of insects also change during plant succession with differences in generation time, migratory ability, overwintering stage and reproductive potential. The degree of niche specialisation and the size of the organisms also vary. The characteristic life-cycle strategies of an early colonising species are discussed and the impact of phytophagous species on early successional plant communities found to be considerable. Single species studies (e.g. Raphanus raphanistrum) enable this effect to be assessed more fully. Insect grazing affects the survival, growth and reproductive potential of a plant species. At a community level insect grazing has an effect comparable to that of vertebrates, namely a reduction in the rate of plant succession.

https://www.jstor.org/stable/info/3544037

Valerie K. Brown

Papers

Interactions between Aboveground and Belowground Biodiversity in Terrestrial Ecosystems: Patterns, Mechanisms, and Feedbacks

Biodiversity and ecosystem functioning in soil

Enhancing pollinator biodiversity in intensive grasslands

Insect herbivores and plant succession

The Locust and Grasshopper Agricultural Manual.