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91.
Chengfu Zhang Rob C. JamiesonFan-Rui Meng Robert J. GordonJagtar Bhatti Charles P.-A. Bourque 《Ecological modelling》2011,222(6):1236-1244
Litter decomposition is a key component in ecosystem material cycling that determines (i) forest soil carbon (C) and nutrient content, (ii) release of carbon dioxide to the atmosphere, and (iii) generation and mass transfer of dissolved organic carbon from terrestrial to aquatic ecosystems. In this study, we provide simulations of long term forest-floor litter dynamics generated with both (i) an existing forest nutrient cycling and biomass growth model (ForNBM) with a single-pool formulation of forest-floor litter decomposition (Zhu et al., 2003. Ecol. Model. 169, 347-360), and (ii) a revised version of the model produced by substituting the single-pool formulation with a three-pool version of the formulation tested against data from litterbag experiments (FLDM; Zhang et al., 2010. Ecol. Model. 221, 1944-1953). This is done to determine the importance of subdividing the litter mass into categories of rates of decay (i.e., fast, slow, and very slow) on model accuracy. Forest-forest litter dynamics simulated with the two models are subsequently compared against field measurements collected at several northern jack pine (Pinus banksiana) stands along a southwest-northeast oriented transect (climate gradient) associated with the Boreal Forest Transect Case Study in northwest Canada. Initial comparison shows that the single-pool formulation underpredicts residual litter mass when forests are <65 years old, largely due to the improper treatment of the very slow decomposing litter component. This underprediction is resolved when the three-pool formulation is used. From a ecosystems-response point of view, the revised ForNBM (with the three-pool formulation) demonstrates that (i) forest-floor litter initially increases with forest growth and reaches a plateau once the forest matures; (ii) the forest floor stores more litter and C at the southern and warmer sites than at the northern sites; and (iii) in a similar climate regime, the forest floor stores more litter and C at productive than at nutrient-poor sites. 相似文献
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JENNIFER K. SCHULTZ JASON D. BAKER ROBERT J. TOONEN ALBERT L. HARTING BRIAN W. BOWEN 《Conservation biology》2011,25(1):124-132
Abstract: The Hawaiian monk seal (Monachus schauinslandi) is one of the most critically endangered marine mammals. Less than 1200 individuals remain, and the species is declining at a rate of approximately 4% per year as a result of juvenile starvation, shark predation, and entanglement in marine debris. Some of these problems may be alleviated by translocation; however, if island breeding aggregates are effectively isolated subpopulations, moving individuals may disrupt local adaptations. In these circumstances, managers must balance the pragmatic need of increasing survival with theoretical concerns about genetic viability. To assess range‐wide population structure of the Hawaiian monk seal, we examined an unprecedented, near‐complete genetic inventory of the species (n =1897 seals, sampled over 14 years) at 18 microsatellite loci. Genetic variation was not spatially partitioned (w=?0.03, p = 1.0), and a Bayesian clustering method provided evidence of one panmictic population (K =1). Pairwise FST comparisons (among 7 island aggregates over 14 annual cohorts) did not reveal temporally stable, spatial reproductive isolation. Our results coupled with long‐term tag‐resight data confirm seal movement and gene flow throughout the Hawaiian Archipelago. Thus, human‐mediated translocation of seals among locations is not likely to result in genetic incompatibilities. 相似文献
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长期撂荒恢复土壤团聚体组成与有机碳分布关系 总被引:6,自引:0,他引:6
为探究撂荒地恢复过程土壤团聚体组成结构及其对土壤碳库累积的影响,本研究选取陕北黄土丘陵区恢复10、 17、 27和42 a撂荒草地为研究对象,以坡耕地FL作为对照,分析不同年限撂荒草地以及耕地土壤(0~20 cm)与(20~40 cm)土层团聚体粒径分布、土壤全土有机碳储量以及团聚体有机碳储量动态特征,从而探究撂荒地土壤团聚体与有机碳之间的相互关联性.结果表明:①耕地恢复为撂荒草地后,土壤大团聚体(2 mm)和中团聚体(2~0.25 mm)数量、平均重量直径(mean weight diameter, MWD)和几何平均直径(geometric mean diameter,GMD)随着撂荒年限显著上升,而土壤微团聚体(0.25~0.053 mm)数量显著下降(P0.05).土壤大团聚体数量、平均重量直径和几何平均直径在层次之间差异显著,表现为0~20 cm显著高于20~40 cm.②经过长期撂荒恢复后,土壤总有机碳储量、大团聚体有机碳储量以及中团聚体有机碳储量显著上升(P0.05),分别上升了1.92、 10.2和3.61倍,而微团聚体有机碳储量显著下降.撂荒恢复促使土壤碳氮化学计量比升高,但在42 a时出现了显著下降趋势.③土壤团聚体对于总有机碳储量的贡献率有80%来自大团聚体,且大团聚体数量随着恢复年限显著增加是大团聚体贡献率高的主要原因.总体而言,撂荒恢复过程中,微团聚体数量持续下降,而大团聚体数量显著增加并促进了土壤有机碳的累积. 相似文献
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Methodological issues in forestry mitigation projects: a case study of Kolar district 总被引:1,自引:1,他引:0
N. H. Ravindranath I. K. Murthy P. Sudha V. Ramprasad M. D. V. Nagendra C. A. Sahana K. G. Srivathsa H. Khan 《Mitigation and Adaptation Strategies for Global Change》2007,12(6):1077-1098
There is a need to assess climate change mitigation opportunities in forest sector in India in the context of methodological
issues such as additionality, permanence, leakage and baseline development in formulating forestry mitigation projects. A
case study of forestry mitigation project in semi-arid community grazing lands and farmlands in Kolar district of Karnataka,
was undertaken with regard to baseline and project scenario development, estimation of carbon stock change in the project,
leakage estimation and assessment of cost-effectiveness of mitigation projects. Further, the transaction costs to develop
project, and environmental and socio-economic impact of mitigation project was assessed.
The study shows the feasibility of establishing baselines and project C-stock changes. Since the area has low or insignificant
biomass, leakage is not an issue. The overall mitigation potential in Kolar for a total area of 14,000 ha under various mitigation
options is 278,380 t C at a rate of 20 t C/ha for the period 2005–2035, which is approximately 0.67 t C/ha/year inclusive
of harvest regimes under short rotation and long rotation mitigation options. The transaction cost for baseline establishment
is less than a rupee/t C and for project scenario development is about Rs. 1.5–3.75/t C. The project enhances biodiversity
and the socio-economic impact is also significant.
相似文献
N. H. RavindranathEmail: |
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