Ecosystem

About: Ecosystem is a research topic. Over the lifetime, 25460 publications have been published within this topic receiving 1291375 citations. The topic is also known as: ecological system & Ecosystem.

Biodiversity effects on soil processes explained by interspecific functional dissimilarity.

Abstract: The loss of biodiversity can have significant impacts on ecosystem functioning, but the mechanisms involved lack empirical confirmation. Using soil microcosms, we show experimentally that functional dissimilarity among detritivorous species, not species number, drives community compositional effects on leaf litter mass loss and soil respiration, two key soil ecosystem processes. These experiments confirm theoretical predictions that biodiversity effects on ecosystem functioning can be predicted by the degree of functional differences among species.

Abundance of common species, not species richness, drives delivery of a real‐world ecosystem service

Abstract: Biodiversity-ecosystem functioning experiments have established that species richness and composition are both important determinants of ecosystem function in an experimental context. Determining whether this result holds for real-world ecosystem services has remained elusive, however, largely due to the lack of analytical methods appropriate for large-scale, associational data. Here, we use a novel analytical approach, the Price equation, to partition the contribution to ecosystem services made by species richness, composition and abundance in four large-scale data sets on crop pollination by native bees. We found that abundance fluctuations of dominant species drove ecosystem service delivery, whereas richness changes were relatively unimportant because they primarily involved rare species that contributed little to function. Thus, the mechanism behind our results was the skewed species-abundance distribution. Our finding that a few common species, not species richness, drive ecosystem service delivery could have broad generality given the ubiquity of skewed species-abundance distributions in nature.

The Role of Bryophytes in Carbon and Nitrogen Cycling

Abstract: management. How does our behavior (including urban development and land-use, water consumption, pollution) influence the movement of energy, water, and elements at local, regional, national or global scales? Will perturbations to chemical and energy cycles alter existing controls on ecosystem processes, and can we learn enough about them for effective regulation? Plants are critical in regulating biogeochemical cycles. Their growth controls the exchange of gases that support life in our current biosphere, and affects soil development. As primary producers, they influence the distribution of energy for higher trophic levels. Understanding how plants influence ecosystem processes requires a multidisciplinary approach drawing on plant physiology and biochemistry, community ecology, and biogeochemistry. Due to their unique physiology and ecology, bryophytes differ from vascular plants in influencing cycles of elements, energy, and water. For example, bryophytes have evolved an effective water relation system. Poikilohydry and desiccation tolerance allow bryophytes to tolerate longer periods of water stress than vascular plants, and to recover quickly with rehydration. With poorly developed conduction systems, water and solutes are taken up over the entire plant surface. Lack of both gametophyte stomata and effective cuticles in many species allows free exchange of solutions and gases across cell surfaces. Thus bryophytes often serve as effective traps for water and nutrients. This also makes them more sensitive to atmospheric chemical deposition than vascular plants. Bryophytes also can tolerate a wide range of temperatures and are found in almost all terrestrial and aquatic environments, including harsh Antarctic environments where vascular plant cover is low (cf. Fogg 1998; Seppelt 1995). Without roots, bryophytes can colonize hard substrates like rock and wood that are poor habitat for vascular species. Bryophytes stabilize soils and prevent the loss of soil and nutrients via erosion, particularly on sand dunes (Martinez & Maun 1999) and in cryptogamic soil crusts (Eldridge 1999; Evans & Johansen 1999). Cation exchange on Sphagnum cell walls releases protons, generating acidity that may inhibit plant and microbial growth (Clymo 1963; Craigie & Maass 1966; Spearing 1972). Finally, bryophytes influence ecosystem succession (Brock & Bregman 1989) through terrestrialization of water bodies, deposition of benthic organic matter or paludification of upland systems. Bryophyte colonization often precedes the establishment of tree surfaces by other canopy-dwelling plants (Nadkarni et al. 2000). Due to their physiology and life history traits, bryophytes influence ecosystem functions by producing organic matter, stabilizing soils or debris, trapping sediments and water, and providing food and habitat for algae, fungi, invertebrates, and amphibians. In this review, my objectives are to highlight several mechanisms by which bryophytes influence carbon (C) and nitrogen (N) cycles within and fluxes from ecosystems. As such, I will focus on how bryophytes fix, intercept, transform, and/or release C and N. My goals are to 1) introduce important processes controlling inputs and outputs of C and N in both terrestrial and aquatic ecosystems, 2) review work on the growth, decomposition, and leaching of bryophyte material, as well as biotic and abiotic controls on these mechanisms, and 3) suggest areas for future research that would advance our understanding of bryophytes in biogeochemical cycling. Current address: U.S. Geological Survey, 345 Middlefield Rd. MS 962, Menlo Park, CA 94025 U.S.A. e-mail: mturetsky@usgs.gov