Definitions of diversity. Measuring species diversity. Choosing an index and interpreting diversity measures. Sampling problems. Structural diversity. Applications of diversity measures. Summary.

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Ecological Diversity and its Measurement

Since 65 million years ago (Ma), Earth's climate has undergone a significant and complex evolution, the finer details of which are now coming to light through investigations of deep-sea sediment cores. This evolution includes gradual trends of warming and cooling driven by tectonic processes on time scales of 10(5) to 10(7) years, rhythmic or periodic cycles driven by orbital processes with 10(4)- to 10(6)-year cyclicity, and rare rapid aberrant shifts and extreme climate transients with durations of 10(3) to 10(5) years. Here, recent progress in defining the evolution of global climate over the Cenozoic Era is reviewed. We focus primarily on the periodic and anomalous components of variability over the early portion of this era, as constrained by the latest generation of deep-sea isotope records. We also consider how this improved perspective has led to the recognition of previously unforeseen mechanisms for altering climate.

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Trends, Rhythms, and Aberrations in Global Climate 65 Ma to Present

Ecological extinction caused by overfishing precedes all other pervasive human disturbance to coastal ecosystems, including pollution, degradation of water quality, and anthropogenic climate change. Historical abundances of large consumer species were fantastically large in comparison with recent observations. Paleoecological, archaeological, and historical data show that time lags of decades to centuries occurred between the onset of overfishing and consequent changes in ecological communities, because unfished species of similar trophic level assumed the ecological roles of overfished species until they too were overfished or died of epidemic diseases related to overcrowding. Retrospective data not only help to clarify underlying causes and rates of ecological change, but they also demonstrate achievable goals for restoration and management of coastal ecosystems that could not even be contemplated based on the limited perspective of recent observations alone.

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Historical overfishing and the recent collapse of coastal 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

The management and conservation of the world's oceans require synthesis of spatial data on the distribution and intensity of human activities and the overlap of their impacts on marine ecosystems. We developed an ecosystem-specific, multiscale spatial model to synthesize 17 global data sets of anthropogenic drivers of ecological change for 20 marine ecosystems. Our analysis indicates that no area is unaffected by human influence and that a large fraction (41%) is strongly affected by multiple drivers. However, large areas of relatively little human impact remain, particularly near the poles. The analytical process and resulting maps provide flexible tools for regional and global efforts to allocate conservation resources; to implement ecosystem-based management; and to inform marine spatial planning, education, and basic research.

/pdf/a-global-map-of-human-impact-on-marine-ecosystems-1r5xgg00oe.pdf

A Global Map of Human Impact on Marine Ecosystems

Frances Lawrence Parker (1906–2002), micropaleontologist and pioneer of paleoceanography

Abundance of color bands in Neogene carbonate sediments on Ontong Java Plateau: a proxy for sedimentation rate?

EXTRACT (SEE PDF FOR FULL ABSTRACT):

A varve chronology with annual resolution (AD 1117-1992) has been developed recently for Santa Barbara Basin. Varve thickness and water content show an exponential trend consistent with expected patterns in the presence of sediment compaction over time. Annual varve thickness was decomposed into orthogonal components using singular spectrum analysis (SSA) to identify and retrieve inter-decadal oscillations. ... This suggests a connection with global-scale decadal cycles identified in the subtropical Pacific gyre circulation and, possibly, with solar-driven phenomena. The near-1600 AD event coincides with (a) a similarly sudden change of state in nearby Santa Monica Basin that triggered the onset of anoxic conditions and the preservation of laminated sediments, (b) an extreme drought over the American Southwest, (c) a transformation of the age structure in a number of forest populations throughout Arizona and New Mexico. Total organic carbon burial flux in Santa Barbara Basin varves also shows a marked change after AD 1600. A possible climatic link is proposed that involves pathways for moisture transport in the Southwest at decadal and longer time scales.

The near-AD 1600 multi-proxy puzzle

Stable carbon and oxygen isotope ratios of planktonic foraminifera of sediment core GeoB1523-2

Pinus torreyana, the Torrey pine, grows in a limited region along the coast in North San Diego County near Del Mar; the oldest trees are somewhat over a century old. The history of its rate of growth is contained in its tree rings, which tell an interesting story about patterns of climate change; thatis, the history of precipitation in the region.

/pdf/torrey-pine-and-climate-change-5fadxhxt8l.pdf

Wolfgang H Berger

Papers

Frances Lawrence Parker (1906–2002), micropaleontologist and pioneer of paleoceanography

Abundance of color bands in Neogene carbonate sediments on Ontong Java Plateau: a proxy for sedimentation rate?

The near-AD 1600 multi-proxy puzzle

Stable carbon and oxygen isotope ratios of planktonic foraminifera of sediment core GeoB1523-2

Torrey Pine and Climate Change