Aboveground Biomass

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Mark C Vanderwel - One of the best experts on this subject based on the ideXlab platform.

  • quantifying variation in forest disturbance and its effects on Aboveground Biomass dynamics across the eastern united states
    Global Change Biology, 2013
    Co-Authors: Mark C Vanderwel, David A Coomes, Drew W Purves
    Abstract:

    The role of tree mortality in the global carbon balance is complicated by strong spatial and temporal heterogeneity that arises from the stochastic nature of carbon loss through disturbance. Characterizing spatio-temporal variation in mortality (including disturbance) and its effects on forest and carbon dynamics is thus essential to understanding the current global forest carbon sink, and to predicting how it will change in future. We analyzed forest inventory data from the eastern United States to estimate plot-level variation in mortality (relative to a long-term background rate for individual trees) for nine distinct forest regions. Disturbances that produced at least a fourfold increase in tree mortality over an approximately 5 year interval were observed in 1–5% of plots in each forest region. The frequency of disturbance was lowest in the northeast, and increased southwards along the Atlantic and Gulf coasts as fire and hurricane disturbances became progressively more common. Across the central and northern parts of the region, natural disturbances appeared to reflect a diffuse combination of wind, insects, disease, and ice storms. By linking estimated covariation in tree growth and mortality over time with a data-constrained forest dynamics model, we simulated the implications of stochastic variation in mortality for long-term Aboveground Biomass changes across the eastern United States. A geographic gradient in disturbance frequency induced notable differences in Biomass dynamics between the least- and most-disturbed regions, with variation in mortality causing the latter to undergo considerably stronger fluctuations in Aboveground stand Biomass over time. Moreover, regional simulations showed that a given long-term increase in mean mortality rates would support greater Aboveground Biomass when expressed through disturbance effects compared with background mortality, particularly for early-successional species. The effects of increased tree mortality on carbon stocks and forest composition may thus depend partly on whether future mortality increases are chronic or episodic in nature.

Xiangcheng Mi - One of the best experts on this subject based on the ideXlab platform.

  • topographic variation in Aboveground Biomass in a subtropical evergreen broad leaved forest in china
    PLOS ONE, 2012
    Co-Authors: Helene C Mullerlandau, Xiangcheng Mi
    Abstract:

    The subtropical forest biome occupies about 25% of China, with species diversity only next to tropical forests. Despite the recognized importance of subtropical forest in regional carbon storage and cycling, uncertainties remain regarding the carbon storage of subtropical forests, and few studies have quantified within-site variation of Biomass, making it difficult to evaluate the role of these forests in the global and regional carbon cycles. Using data for a 24-ha census plot in east China, we quantify Aboveground Biomass, characterize its spatial variation among different habitats, and analyse species relative contribution to the total Aboveground Biomass of different habitats. The average Aboveground Biomass was 223.0 Mg ha−1 (bootstrapped 95% confidence intervals [217.6, 228.5]) and varied substantially among four topographically defined habitats, from 180.6 Mg ha−1 (bootstrapped 95% CI [167.1, 195.0]) in the upper ridge to 245.9 Mg ha−1 (bootstrapped 95% CI [238.3, 253.8]) in the lower ridge, with upper and lower valley intermediate. In consistent with our expectation, individual species contributed differently to the total Aboveground Biomass of different habitats, reflecting significant species habitat associations. Different species show differently in habitat preference in terms of Biomass contribution. These patterns may be the consequences of ecological strategies difference among different species. Results from this study enhance our ability to evaluate the role of subtropical forests in the regional carbon cycle and provide valuable information to guide the protection and management of subtropical broad-leaved forest for carbon sequestration and carbon storage.

Yingli Wang - One of the best experts on this subject based on the ideXlab platform.

  • estimation of grassland canopy height and Aboveground Biomass at the quadrat scale using unmanned aerial vehicle
    Remote Sensing, 2018
    Co-Authors: Huifang Zhang, Yi Sun, Li Chang, Yu Qin, Jianjun Chen, Yan Qin, Yingli Wang
    Abstract:

    Aboveground Biomass is a key indicator of a grassland ecosystem. Accurate estimation from remote sensing is important for understanding the response of grasslands to climate change and disturbance at a large scale. However, the precision of remote sensing inversion is limited by a lack in the ground truth and scale mismatch with satellite data. In this study, we first tried to establish a grassland Aboveground Biomass estimation model at 1 m2 quadrat scale by conducting synchronous experiments of unmanned aerial vehicle (UAV) and field measurement in three different grassland ecosystems. Two flight modes (the new QUADRAT mode and the commonly used MOSAIC mode) were used to generate point clouds for further processing. Canopy height metrics of each quadrat were then calculated using the canopy height model (CHM). Correlation analysis showed that the mean of the canopy height model (CHM_mean) had a significant linear relationship with field height (R2 = 0.90, root mean square error (RMSE) = 19.79 cm, rRMSE = 16.5%, p < 0.001) and a logarithmic relationship with field Aboveground Biomass (R2 = 0.89, RMSE = 91.48 g/m2, rRMSE = 16.11%, p < 0.001). We concluded our study by conducting a preliminary application of estimation of the Aboveground Biomass at a plot scale by jointly using UAV and the constructed 1 m2 quadrat scale estimation model. Our results confirmed that UAV could be used to collect large quantities of ground truths and bridge the scales between ground truth and remote sensing pixels, which were helpful in improving the accuracy of remote sensing inversion of grassland Aboveground Biomass.

Arshad Ali - One of the best experts on this subject based on the ideXlab platform.

  • plant coverage is a potential ecological indicator for species diversity and Aboveground Biomass in semi steppe rangelands
    Ecological Indicators, 2018
    Co-Authors: Anvar Sanaei, Arshad Ali, Mohammad Ali Zare Chahouki, Mohammad Jafari
    Abstract:

    Abstract The relationships between species diversity and Aboveground Biomass remain highly debated in contemporary ecology. Here, we proposed the following three hypotheses by evaluating three different paths between species diversity indices (species richness, evenness, Shannon’s species diversity, and a combination of species richness and evenness) and plant coverage for explaining variation in Aboveground Biomass, in addition to the influences of abiotic factors and disturbance intensities: 1) plant coverage increases species diversity through light capture and use in the vertical physical space; 2) species diversity increases plant coverage through species coexistence; and 3) species diversity and plant coverage may provide positive response to each other, and as a consequence enhance Aboveground Biomass in natural rangelands. We used structural equation models to explicitly test these hypotheses using biophysical data from 735 quadrats in semi-steppe rangelands in Iran. In all tested models, plant coverage possessed strongest positive effect on species richness and Shannon’s species diversity but not on species evenness, and hence strongly determined Aboveground Biomass as compared to species diversity indices. Disturbance intensity decreased Aboveground Biomass directly and indirectly via plant coverage than that via species diversity, indicating that plant coverage is sensitive to disturbance intensities for driving Aboveground Biomass. Species richness or Shannon’s diversity substantially enhanced Aboveground Biomass indirectly via plant coverage, indicating that plant coverage is a linking mechanism for the positive relationships between biodiversity and Aboveground Biomass. Practically, this study suggests that rotational grazing system might be a suitable choice for the enhancement of plant coverage and Aboveground Biomass while conserving biodiversity. Theoretically, this study suggests that plant coverage is a sustainable ecological indicator or linking mechanism for high species diversity and Aboveground Biomass in studied rangelands and other ecosystems in general.

  • community weighted mean of leaf traits and divergence of wood traits predict Aboveground Biomass in secondary subtropical forests
    Science of The Total Environment, 2017
    Co-Authors: Arshad Ali, Enrong Yan, Scott X Chang, Junyang Cheng, Xiangyu Liu
    Abstract:

    Subtropical forests are globally important in providing ecological goods and services, but it is not clear whether functional diversity and composition can predict Aboveground Biomass in such forests. We hypothesized that high Aboveground Biomass is associated with high functional divergence (FDvar, i.e., niche complementarity) and community-weighted mean (CWM, i.e., mass ratio; communities dominated by a single plant strategy) of trait values. Structural equation modeling was employed to determine the direct and indirect effects of stand age and the residual effects of CWM and FDvar on Aboveground Biomass across 31 plots in secondary forests in subtropical China. The CWM model accounted for 78, 20, 6 and 2% of the variation in Aboveground Biomass, nitrogen concentration in young leaf, plant height and specific leaf area of young leaf, respectively. The FDvar model explained 74, 13, 7 and 0% of the variation in Aboveground Biomass, plant height, twig wood density and nitrogen concentration in young leaf, respectively. The variation in Aboveground Biomass, CWM of leaf nitrogen concentration and specific leaf area, and FDvar of plant height, twig wood density and nitrogen concentration in young leaf explained by the joint model was 86, 20, 13, 7, 2 and 0%, respectively. Stand age had a strong positive direct effect but low indirect positive effects on Aboveground Biomass. Aboveground Biomass was negatively related to CWM of nitrogen concentration in young leaf, but positively related to CWM of specific leaf area of young leaf and plant height, and FDvar of plant height, twig wood density and nitrogen concentration in young leaf. Leaf and wood economics spectra are decoupled in regulating the functionality of forests, communities with diverse species but high nitrogen conservative and light acquisitive strategies result in high Aboveground Biomass, and hence, supporting both the mass ratio and niche complementarity hypotheses in secondary subtropical forests.

Xiangyu Liu - One of the best experts on this subject based on the ideXlab platform.

  • community weighted mean of leaf traits and divergence of wood traits predict Aboveground Biomass in secondary subtropical forests
    Science of The Total Environment, 2017
    Co-Authors: Arshad Ali, Enrong Yan, Scott X Chang, Junyang Cheng, Xiangyu Liu
    Abstract:

    Subtropical forests are globally important in providing ecological goods and services, but it is not clear whether functional diversity and composition can predict Aboveground Biomass in such forests. We hypothesized that high Aboveground Biomass is associated with high functional divergence (FDvar, i.e., niche complementarity) and community-weighted mean (CWM, i.e., mass ratio; communities dominated by a single plant strategy) of trait values. Structural equation modeling was employed to determine the direct and indirect effects of stand age and the residual effects of CWM and FDvar on Aboveground Biomass across 31 plots in secondary forests in subtropical China. The CWM model accounted for 78, 20, 6 and 2% of the variation in Aboveground Biomass, nitrogen concentration in young leaf, plant height and specific leaf area of young leaf, respectively. The FDvar model explained 74, 13, 7 and 0% of the variation in Aboveground Biomass, plant height, twig wood density and nitrogen concentration in young leaf, respectively. The variation in Aboveground Biomass, CWM of leaf nitrogen concentration and specific leaf area, and FDvar of plant height, twig wood density and nitrogen concentration in young leaf explained by the joint model was 86, 20, 13, 7, 2 and 0%, respectively. Stand age had a strong positive direct effect but low indirect positive effects on Aboveground Biomass. Aboveground Biomass was negatively related to CWM of nitrogen concentration in young leaf, but positively related to CWM of specific leaf area of young leaf and plant height, and FDvar of plant height, twig wood density and nitrogen concentration in young leaf. Leaf and wood economics spectra are decoupled in regulating the functionality of forests, communities with diverse species but high nitrogen conservative and light acquisitive strategies result in high Aboveground Biomass, and hence, supporting both the mass ratio and niche complementarity hypotheses in secondary subtropical forests.