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Forest Chronosequence (forest + chronosequence)
Selected AbstractsRapid Recovery of Biomass, Species Richness, and Species Composition in a Forest Chronosequence in Northeastern Costa RicaBIOTROPICA, Issue 5 2009Susan G. Letcher ABSTRACT Secondary forests are a vital part of the tropical landscape, and their worldwide extent and importance continues to increase. Here, we present the largest chronosequence data set on forest succession in the wet tropics that includes both secondary and old-growth sites. We performed 0.1 ha vegetation inventories in 30 sites in northeastern Costa Rica, including seven old-growth forests and 23 secondary forests on former pastures, ranging from 10 to 42 yr. The secondary forest sites were formerly pasture for intervals of <1,25 yr. Aboveground biomass in secondary forests recovered rapidly, with sites already exhibiting values comparable to old growth after 21,30 yr, and biomass accumulation was not impacted by the length of time that a site was in pasture. Species richness reached old-growth levels in as little as 30 yr, although sites that were in pasture for > 10 yr had significantly lower species richness. Forest cover near the sites at the time of forest establishment did not significantly impact biomass or species richness, and the species composition of older secondary forest sites (>30 yr) converged with that of old growth. These results emphasize the resilience of tropical ecosystems in this region and the high conservation value of secondary forests. [source] Soil carbon fluxes and stocks in a Great Lakes forest chronosequenceGLOBAL CHANGE BIOLOGY, Issue 1 2009JIANWU TANG Abstract We measured soil respiration and soil carbon stocks, as well as micrometeorological variables in a chronosequence of deciduous forests in Wisconsin and Michigan. The chronosequence consisted of (1) four recently disturbed stands, including a clearcut and repeatedly burned stand (burn), a blowdown and partial salvage stand (blowdown), a clearcut with sparse residual overstory (residual), and a regenerated stand from a complete clearcut (regenerated); (2) four young aspen (Populus tremuloides) stands in average age of 10 years; (3) four intermediate aspen stands in average age of 26 years; (4) four mature northern hardwood stands in average age of 73 years; and (5) an old-growth stand approximately 350-years old. We fitted site-based models and used continuous measurements of soil temperature to estimate cumulative soil respiration for the growing season of 2005 (days 133,295). Cumulative soil respiration in the growing season was estimated to be 513, 680, 747, 747, 794, 802, 690, and 571 g C m,2 in the burn, blowdown, residual, regenerated, young, intermediate, mature, and old-growth stands, respectively. The measured apparent temperature sensitivity of soil respiration was the highest in the regenerated stand, and declined from the young stands to the old-growth. Both, cumulative soil respiration and basal soil respiration at 10 °C, increased during stand establishment, peaked at intermediate age, and then decreased with age. Total soil carbon at 0,60 cm initially decreased after harvest, and increased after stands established. The old-growth stand accumulated carbon in deep layers of soils, but not in the surface soils. Our study suggests a complexity of long-term soil carbon dynamics, both in vertical depth and temporal scale. [source] Comparison of two plant functional approaches to evaluate natural restoration along an old-field , deciduous forest chronosequenceJOURNAL OF VEGETATION SCIENCE, Issue 2 2009Isabelle Aubin Abstract Question: Are direct and indirect trait-based approaches similar in their usefulness to synthesize species responses to successional stages? Location: Northern hardwood forests, Québec, Canada (45°01,,45°08,N; 73°58,,74°21,W). Methods: Two different trait-based approaches were used to relate plant functional traits to succession on an old-field , deciduous forest chronosequence: (i) a frequently used approach based on co-occurrence of traits (emergent groups), and (ii) a new version of a direct functional approach at the trait level (the fourth-corner method). Additionally, we selected two different cut-off levels for the herb subset of the emergent group classification in order to test its robustness and ecological relevance. Results: Clear patterns of trait associations with stand developmental stages emerged from both the emergent group and the direct approach at the trait level. However, the emergent group classification was found to hide some trait-level differences such as a shift in seed size, light requirement and plant form along the chronosequence. Contrasting results were obtained for the seven or nine group classification of the herbaceous subset, illustrating how critical is the number of groups for emergent group classification. Conclusion: The simultaneous use of two different trait-based approaches provided a robust and comprehensive characterization of vegetation responses in the old-field , deciduous forest chronosequence. It also underlines the different goals as well as the limitations and benefits of these two approaches. Both approaches indicated that abandoned pastures of the northern hardwood biome have good potential for natural recovery. Conversion of these lands to other functions may lead to irremediable loss of biodiversity. [source] | ||||||||||