Topic
Productivity (ecology)
About: Productivity (ecology) is a research topic. Over the lifetime, 6011 publications have been published within this topic receiving 226886 citations. The topic is also known as: production & biological productivity.
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TL;DR: Evidence from 1982 and 1983 suggests effects on higher organisms such as fish, seabirds, and marine mammals, but several more years of observation are required to accurately determine the magnitude of the consequences on these higher trophic levels.
Abstract: Observations of the 1982-1983 El Nino make it possible to relate the anomalous ocean conditions to specific biological responses. In October 1982 upwelling ecosystems in the eastern equatorial Pacific began a series of transitions from the normal highly productive condition to greatly reduced productivity. The highly productive condition had returned by July 1983. Nutrients, phytoplankton biomass, and primary productivity are clearly regulated by the physical changes of El Nino. Evidence from 1982 and 1983 also suggests effects on higher organisms such as fish, seabirds, and marine mammals, but several more years of observation are required to accurately determine the magnitude of the consequences on these higher trophic levels.
739 citations
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United States Geological Survey1, Smithsonian Tropical Research Institute2, University of Nebraska–Lincoln3, University of Melbourne4, University of Cambridge5, University College London6, National University of Tucumán7, Department of National Parks, Wildlife and Plant Conservation8, Smithsonian Institution9, National University of Colombia10, Wildlife Conservation Society11, University of La Réunion12, University of Washington13, Chinese Academy of Sciences14, Oregon State University15, University of California, Los Angeles16, Tunghai University17, National University of Jujuy18, Kasetsart University19, National Dong Hwa University20, Landcare Research21, University of Alcalá22
TL;DR: A global analysis of 403 tropical and temperate tree species shows that for most species mass growth rate increases continuously with tree size, which means large, old trees do not act simply as senescent carbon reservoirs but actively fix large amounts of carbon compared to smaller trees.
Abstract: Forests are major components of the global carbon cycle, providing substantial feedback to atmospheric greenhouse gas concentrations. Our ability to understand and predict changes in the forest carbon cycle--particularly net primary productivity and carbon storage--increasingly relies on models that represent biological processes across several scales of biological organization, from tree leaves to forest stands. Yet, despite advances in our understanding of productivity at the scales of leaves and stands, no consensus exists about the nature of productivity at the scale of the individual tree, in part because we lack a broad empirical assessment of whether rates of absolute tree mass growth (and thus carbon accumulation) decrease, remain constant, or increase as trees increase in size and age. Here we present a global analysis of 403 tropical and temperate tree species, showing that for most species mass growth rate increases continuously with tree size. Thus, large, old trees do not act simply as senescent carbon reservoirs but actively fix large amounts of carbon compared to smaller trees; at the extreme, a single big tree can add the same amount of carbon to the forest within a year as is contained in an entire mid-sized tree. The apparent paradoxes of individual tree growth increasing with tree size despite declining leaf-level and stand-level productivity can be explained, respectively, by increases in a tree's total leaf area that outpace declines in productivity per unit of leaf area and, among other factors, age-related reductions in population density. Our results resolve conflicting assumptions about the nature of tree growth, inform efforts to undertand and model forest carbon dynamics, and have additional implications for theories of resource allocation and plant senescence.
692 citations
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TL;DR: In this article, the authors review 72 published articles to elucidate characteristics of biomass allocation and productivity of mangrove forests and also introduce recent progress on the study of MANGEO to solve the site and species-specific problems.
688 citations
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TL;DR: These studies suggest that savanna trees completed more intensely with understory plants at wetters sites, where their roots terminated in or near crown zones, than at drier sites,Where their roots extended farther into open grassland, and contributed more to regrowth after severe defoliation than to growth under more normal conditions.
Abstract: To determine why herbaceous productivity in tropical and subtropical savannas is often significantly higher under crowns of isolated trees than in adjacent grass—lands, experimental plots were established in three concentric zones, crown, tree—root, and grassland, surrounding isolated trees of Acacia tortilis in low—rainfall and high—rainfall savannas in Tsavo National Park, Kenya. Plots were fertilized (to determine the importance of nutrient enrichment by trees), shaded (to determine the importance of crown shade), fertilized and shaded (to identify fertilizer x shade interactions), or trenched (tree roots entering plots were severed to determine the importance of belowground competition between overstory trees and understory herbaceous plants). In addition, vertical root distributions of trees and herbaceous species were determined, and root systems of A. tortilis saplings were excavated. At both sites fertilization significantly increased herbaceous productivity in tree—root and grassland zones, but not in canopy zones; artificial shade had no effect on productivity at the low—rainfall site but increased productivity in the tree—root zone at the high—rainfall site; and severing tree roots had no effect on herbaceous productivity at the low—rainfall site, but increased productivity in the crown and tree—root zones at the high—rainfall site. Roots of herbaceous and woody species co—occurred within the same soil horizons, but tree roots extended farther into grasslands at the low—rainfall site than at the high—rainfall site. These studies suggest that savanna trees completed more intensely with understory plants at wetters sites, where their roots terminated in or near crown zones, than at drier sites, where their roots extended farther into open grassland. Nutrients added by trees to crown zones in the form of tree litter and animal droppings increased understory productivity by fertilizing nutrient—limited soils. Shade contributed more to regrowth after severe defoliation than to growth under more normal conditions.
684 citations
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TL;DR: It is proposed that a large share of the world’s unproductive lakes, within natural variations of organic carbon and nutrient input, are limited by light and not by nutrients, which is inconsistent with the idea that nutrient supply primarily controls lake productivity.
Abstract: Productivity denotes the rate of biomass synthesis in ecosystems and is a fundamental characteristic that frames ecosystem function and management. Limitation of productivity by nutrient availabili ...
670 citations