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

This paper describes the technical development and accuracy assessment of the most recent and improved version of the SoilGrids system at 250m resolution (June 2016 update). SoilGrids provides global predictions for standard numeric soil properties (organic carbon, bulk density, Cation Exchange Capacity (CEC), pH, soil texture fractions and coarse fragments) at seven standard depths (0, 5, 15, 30, 60, 100 and 200 cm), in addition to predictions of depth to bedrock and distribution of soil classes based on the World Reference Base (WRB) and USDA classification systems (ca. 280 raster layers in total). Predictions were based on ca. 150,000 soil profiles used for training and a stack of 158 remote sensing-based soil covariates (primarily derived from MODIS land products, SRTM DEM derivatives, climatic images and global landform and lithology maps), which were used to fit an ensemble of machine learning methods-random forest and gradient boosting and/or multinomial logistic regression-as implemented in the R packages ranger, xgboost, nnet and caret. The results of 10-fold cross-validation show that the ensemble models explain between 56% (coarse fragments) and 83% (pH) of variation with an overall average of 61%. Improvements in the relative accuracy considering the amount of variation explained, in comparison to the previous version of SoilGrids at 1 km spatial resolution, range from 60 to 230%. Improvements can be attributed to: (1) the use of machine learning instead of linear regression, (2) to considerable investments in preparing finer resolution covariate layers and (3) to insertion of additional soil profiles. Further development of SoilGrids could include refinement of methods to incorporate input uncertainties and derivation of posterior probability distributions (per pixel), and further automation of spatial modeling so that soil maps can be generated for potentially hundreds of soil variables. Another area of future research is the development of methods for multiscale merging of SoilGrids predictions with local and/or national gridded soil products (e.g. up to 50 m spatial resolution) so that increasingly more accurate, complete and consistent global soil information can be produced. SoilGrids are available under the Open Data Base License.

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SoilGrids250m: Global gridded soil information based on machine learning

▪ Abstract Estimates of global wetland area range from 5.3 to 12.8 million km2. About half the global wetland area has been lost, but an international treaty (the 1971 Ramsar Convention) has helped 144 nations protect the most significant remaining wetlands. Because most nations lack wetland inventories, changes in the quantity and quality of the world's wetlands cannot be tracked adequately. Despite the likelihood that remaining wetlands occupy less than 9% of the earth's land area, they contribute more to annually renewable ecosystem services than their small area implies. Biodiversity support, water quality improvement, flood abatement, and carbon sequestration are key functions that are impaired when wetlands are lost or degraded. Restoration techniques are improving, although the recovery of lost biodiversity is challenged by invasive species, which thrive under disturbance and displace natives. Not all damages to wetlands are reversible, but it is not always clear how much can be retained through re...

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Wetland resources : Status, trends, ecosystem services, and restorability

. The carbon burial in vegetated sediments, ignored in past assessments of carbon burial in the ocean, was evaluated using a bottom-up approach derived from upscaling a compilation of published individual estimates of carbon burial in vegetated habitats (seagrass meadows, salt marshes and mangrove forests) to the global level and a top-down approach derived from considerations of global sediment balance and a compilation of the organic carbon content of vegeatated sediments. Up-scaling of individual burial estimates values yielded a total carbon burial in vegetated habitats of 111 Tmol C y-1. The total burial in unvegetated sediments was estimated to be 126 Tg C y-1, resulting in a bottom-up estimate of total burial in the ocean of about 244 Tg C y-1, two-fold higher than estimates of oceanic carbon burial that presently enter global carbon budgets. The organic carbon concentrations in vegetated marine sediments exceeds by 2 to 10-fold those in shelf/deltaic sediments. Top-down recalculation of ocean sediment budgets to account for these, previously neglected, organic-rich sediments, yields a top-down carbon burial estimate of 216 Tg C y-1, with vegetated coastal habitats contributing about 50%. Even though vegetated carbon burial contributes about half of the total carbon burial in the ocean, burial represents a small fraction of the net production of these ecosystems, estimated at about 3388 Tg C y-1, suggesting that bulk of the benthic net ecosystem production must support excess respiration in other compartments, such as unvegetated sediments and the coastal pelagic compartment. The total excess organic carbon available to be exported to the ocean is estimated at between 1126 to 3534 Tg C y-1, the bulk of which must be respired in the open ocean. Widespread loss of vegetated coastal habitats must have reduced carbon burial in the ocean by about 30 Tg C y-1, identifying the destruction of these ecosystems as an important loss of CO2 sink capacity in the biosphere.

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Major role of marine vegetation on the oceanic carbon cycle

. In this forum paper we discuss how soil scientists can help to reach the recently adopted UN Sustainable Development Goals (SDGs) in the most effective manner. Soil science, as a land-related discipline, has important links to several of the SDGs, which are demonstrated through the functions of soils and the ecosystem services that are linked to those functions (see graphical abstract in the Supplement). We explore and discuss how soil scientists can rise to the challenge both internally, in terms of our procedures and practices, and externally, in terms of our relations with colleague scientists in other disciplines, diverse groups of stakeholders and the policy arena. To meet these goals we recommend the following steps to be taken by the soil science community as a whole: (i) embrace the UN SDGs, as they provide a platform that allows soil science to demonstrate its relevance for realizing a sustainable society by 2030; (ii) show the specific value of soil science: research should explicitly show how using modern soil information can improve the results of inter- and transdisciplinary studies on SDGs related to food security, water scarcity, climate change, biodiversity loss and health threats; (iii) take leadership in overarching system analysis of ecosystems, as soils and soil scientists have an integrated nature and this places soil scientists in a unique position; (iii) raise awareness of soil organic matter as a key attribute of soils to illustrate its importance for soil functions and ecosystem services; (iv) improve the transfer of knowledge through knowledge brokers with a soil background; (v) start at the basis: educational programmes are needed at all levels, starting in primary schools, and emphasizing practical, down-to-earth examples; (vi) facilitate communication with the policy arena by framing research in terms that resonate with politicians in terms of the policy cycle or by considering drivers, pressures and responses affecting impacts of land use change; and finally (vii) all this is only possible if researchers, with soil scientists in the front lines, look over the hedge towards other disciplines, to the world at large and to the policy arena, reaching over to listen first, as a basis for genuine collaboration.

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The significance of soils and soil science towards realization of the United Nations sustainable development goals

Effects of different topsoil properties on apparent electrical conductivity under varying soil water contents

Dan H. Yaalon was one of themost influential soil scientists in many decades, a long-standing faculty member of the Institute of Earth Sciences of the Hebrew University of Jerusalem, a much decorated scientist with colleagues from many disciplines, and a devoted family man. Dan passed away on Wednesday 29 January 2014. He was 89. Dan touched the ideas, the research, and students ofmany scientists. He traveled widely as a way to encourage soil science, to accelerate his own soils education, and to represent soil science to the world. I never met Dan, but I corresponded with him electronically over many years, as did many. Recently, we co-wrote two papers, and throughout the writing he worried that he was not up on the literature and thus not a strong co-author. His contributions as co-author were classic Yaalon — intense, critical, and creative. Dan's soil scholarship is remarkable for both its fundamental nature and its breadth. He is one of only three winners of the V.V. Dokuchaev Prize given by the International Union of Soil Sciences. By the end of his career, he had made signature contributions to:

In memoriam: Dan Hardy Yaalon 1924-2014

Gender equity is a concern in many scientific fields, including soil science. Lower percentages of women work as soil scientists than we have in the general population; fewer opportunities to serve on committees or as invited speakers at scientific meetings; lower selection rates for scientific awards; unconscious bias; tension with work-life balance; poor funding and pay; lack of career progression and a lack of networking opportunities. Advances have been made in many countries, although major discrepancies still exist and women are overall still a minority in soil science and related fields.A review of international gender equity issues in soil science was undertaken by requesting gender data from 70 national soil science societies around the world; forty-three societies responded. Female members ranged from 0% to 69%. Thirty-six of the 43 societies had more male than female members; the global average was 68% male and 32% female. Some societies noted that women make up a majority of the younger soil science generation or women make up a larger percentage of the younger membership than of the total membership in their society. These findings indicate there is some progress in gender equity in these countries. However, higher numbers of women do not always mean the reasons for those higher numbers are positive. For example, the Bulgarian Soil Science Society mentioned that women were a majority of their soil scientists because soil science did not pay well and men would not take such a low-paying job. Twenty percent of the national soil science societies belonging to the International Union of Soil Sciences (IUSS) have a woman as their president. However, this is lower than the average female membership (32%) in these societies. This is an indication that women are underrepresented in leadership roles.A rethinking of gender equity is needed to create a new paradigm that allows us:1. To create an inclusive perspective that encourages respect, collaboration and solidarity between the genders. An education based on the full understanding that &#8220;equality does not mean that women and men will become the same but that women&#8217;s and men&#8217;s rights, responsibilities and opportunities will not depend on whether they are born male or female.&#8221;2. An education that recognizes that soil is not only a natural resource, but also provides social, economic, cultural, political and patrimonial good. The soil not only allows&#160;humans to live on it, it supplies food, water and a legitimate sustenance to overcome poverty and to construct an identity, cultural and economic independence.Therefore, legitimate land ownership is a key element in achieving gender equality for the construction of a just and equitable life, but also the only real way to end all forms of discrimination against women and girls. To improve equity in the sciences, including soil science, we need to educate in a way that changes the gender stereotypes that link science to stereotypes about masculinity. There is no equality without economic independence, and there is no economic independence without equal access to land ownership and land care.

International Gender Equity in Soil Science: A Social Equity Issue

Many who engage in soil survey have long desired discovery of a remote sensing technique that differentiates individual soil series. As research in precision agriculture has begun, many other agricultural scientists have also begun evaluating remote sensing tools for soil mapping purposes. Soil electrical conductivity (EC), as measured by instruments including the Geonics® EM-38, has shown promise as a soil survey tool. Most of the work done along these lines to date has involved comparing soil EC patterns to Order 1 or 2 soil surveys. It is important that we understand how certain field conditions that might be encountered during the course of a typical soil survey affect soil EC readings. Therefore, the purpose of this dissertation was to identify field conditions that might affect soil EC readings obtained with the EM-38 and then conduct investigations to determine what, if any, affect those field conditions had. The relationships between soil moisture and soil EC were investigated in the field, and between soil moisture, temperature, carbonate content, and soil EC were investigated in the laboratory. The possible influence of diurnal temperature changes and changes in bulk density in the upper few cm of the soil on EC readings obtained with the EM-38 was studied, as was the possible influence of crop residue cover on soil EC readings. Results show that soil water content is often highly correlated to soil EC, and the influence of soil water content is at least two orders of magnitude greater than the influence of soil temperature or carbonate content in determining soil EC. Diurnal temperature fluctuations and crop residues covering the soil surface did not affect soil EC values, but changes in bulk density did. Therefore, it was concluded that knowledge of soil moisture conditions might allow a soil surveyor to anticipate the expected range of soil EC values for a

https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=1415&context=rtd

Eric C. Brevik

Papers

Effects of different topsoil properties on apparent electrical conductivity under varying soil water contents

In memoriam: Dan Hardy Yaalon 1924-2014

International Gender Equity in Soil Science: A Social Equity Issue

Evaluation of selected factors that may influence the application of electromagnetic induction technology to soil science investigations in Iowa

On the Soil in Soil Survey Horizons (1960–2009)