共查询到7条相似文献,搜索用时 15 毫秒
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Variation in biomass expansion factors for China’s forests in relation to forest type, climate, and stand development 总被引:1,自引:0,他引:1
Yunjian Luo Xiaoke Wang Xiaoquan Zhang Yin Ren Hendrik Poorter 《Annals of Forest Science》2013,70(6):589-599
? Context
Biomass expansion factors (BEFs, defined as the ratios of tree component biomass (branch, leaf, aboveground section, root, and whole) to stem biomass) are important parameters for quantifying forest biomass and carbon stock. However, little information is available about possible causes of the variability in BEFs at large scales.? Aims
We examined whether and how BEFs vary with forest types, climate (mean annual temperature, MAT; mean annual precipitation, MAP), and stand development (stand age and size) at the national scale for China.? Method
Using our compiled biomass dataset, we calculated values for BEFs and explored their relationships to forest types, climate, and stand development.? Results
BEFs varied greatly across forest types and functional groups. They were significantly related to climate and stand development (especially tree height). However, the relationships between BEFs and MAT and MAP were generally different in deciduous forests and evergreen forests, and BEF–climate relationships were weaker in deciduous forests than in evergreen forests and pine forests.? Conclusion
To reduce uncertainties induced by BEFs in estimates of forest biomass and carbon stock, values for BEFs should be applied for a specified forest, and BEF functions with influencing factors (e.g., tree height and climate) should be developed as predictor variables for the specified forest. 相似文献4.
Nothofagus antarctica forests in south Patagonia are usually used as silvopastoral systems but how grasses and trees compete for specific resources, such as nitrogen in these systems is unknown. To understand interactions between grasses and N. antarctica trees for N, an experiment with 15N labeled fertilizer was carried out comparing N absorption by grasses growing under trees (silvopastoral system) with an open site. Labeled 15NH 4 15 NO3 fertilizer at 10 % atom excess was added in spring at both sites and 15N was measured in herbage, soil and trees every 30 days during the growing season. Soil was the component that containing the greatest amount of N and greatest 15N recovery. Grasses growing in the silvopastoral system absorbed almost double of the fertilizer applied than grasses in the open site (32.4 kg N ha?1derived from fertilizer based on 15N recovery). Roots were also an important fate for N absorbed, representing 50 and 63 % of total 15N recovered in grass roots of open and silvopastoral sites, respectively. Trees absorbed 69 % less applied N than grasses in the silvopastoral system; being mainly allocated in small branches, sapwood and fine roots. Overall, 15N recovery was 65 % higher in the silvopastoral system (tree + grasses) than in the open site (grasses). Silvopastoral system made more efficient use of the 15N added. These results indicated that N. antarctica trees in the silvopastoral system may “facilitate” fertilizer N absorption of grasses by improving environmental conditions like water availability or by reducing competition for inorganic N between soil microorganisms and plants. 相似文献
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We demonstrate a method for evaluating the appropriate number of samples required to estimate plant species richness in different
forest types within a forested landscape. In each of 36 plots (0.1 ha each) from 5 forest types (deciduous broad-leaved secondary
forest and 4 categories of coniferous plantation classified according to stand age) in central Japan, 40 quadrats of 1 × 1 m
were set in a regular pattern; the total number of quadrats in each forest type ranged from 200 to 400. In each plot, the
number of observed species in 40 quadrats ranged from 60 to 80% of the number of species estimated by the rarefaction method
for each forest type. Sampling 30 quadrats detected approximately 90% of the observed species in each plot that were detected
using 40 quadrats. In specific functional groups (i.e., tall trees and weed species), the ratios of both tall trees and weed
species to all species were at equilibrium for 30 or more quadrats. For fewer than 30 quadrats these ratios were highly variable.
No significant differences were found among forest types in the ratio of the observed number of species in each plot to the
estimated number of species calculated using the rarefaction method, and in sampling efficiency estimated by use of non-parametric
estimators. We concluded that the number of samples does not need to be changed according to forest type or plantation stand
age in the studied landscape, and that the method used to evaluate the number of samples could be useful. 相似文献
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Johanna Croce Ernesto I.Badano Carolina B.Trigo Fernanda Martinez-Galvez Andrés Tálamo 《林业研究》2022,(4):1197-1207
Knowing what native trees can recr uit on degraded areas allows selecting the best species to restore these sites. However, as this information is not often available, experimentation is required before large-scale planting. This study used ex situ experiments to make these decisions on recruitment. Competition with r-strategist plants, excessive solar radiation and water shortage commonly impair tree recruitment in open habitats. The experiments focused on the interactions among these factors a... 相似文献
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The origin of a seed strongly impacts its traits, and both origin and seed traits influence seed germination and seedling development. However, in many instances, this effect on the seedling does not persist into adulthood, and little is known about how seed traits and original environment affect seedling/tree growth over time. In this study, seed size, seed mass, seedling/tree growth and origins were collected and determined for 23 provenances of Quercus acutissima from across China. Origin variables correlated well with seed size and seed mass. In stepwise multiple regressions, a longitudinal aridity index explained 49.2–68.7% of the total variation in seed size and mass, while only seed width was correlated with seedling/tree height (H) and diameter at the ground (D) from seed traits and origins. The total variance in H and D explained by the models decreased over time, for example, the R 2 value of the models for H declined from 0.477 in the first year to 0.224 in the fourth year; no models was significant in the fifth year. These results indicate that seed size, regulated by the longitudinal aridity index strongly impacted seedling and tree growth, but the strength of the influence decreased over time, and disappeared after 4 years. 相似文献