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461.
Decaying root systems of harvested trees can be a significant component of belowground carbon storage, especially in intensively
managed forests where harvest occurs repeatedly in relatively short rotations. Based on destructive sampling of root systems
of harvested loblolly pine trees, we estimated that root systems contained about 32% (17.2 Mg ha−1) at the time of harvest, and about 13% (6.1 Mg ha−1) of the soil organic carbon 10 years later. Based on the published roundwood output data, we estimated belowground biomass
at the time of harvest for loblolly-shortleaf pine forests harvested between 1995 and 2005 in South Carolina. We then calculated
C that remained in the decomposing root systems in 2005 using the decay function developed for loblolly pine. Our calculations
indicate that the amount of C stored in decaying roots of loblolly-shortleaf pine forests harvested between 1995 and 2005
in South Carolina was 7.1 Tg. Using a simple extrapolation method, we estimated 331.8 Tg C stored in the decomposing roots
due to timber harvest from 1995 to 2005 in the conterminous USA. To fully account for the C stored in the decomposing roots
of the US forests, future studies need (1) to quantify decay rates of coarse roots for major tree species in different regions,
and (2) to develop a methodology that can determine C stock in decomposing roots resulting from natural mortality. 相似文献
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SPACSYS: Integration of a 3D root architecture component to carbon, nitrogen and water cycling—Model description 总被引:1,自引:0,他引:1
L. Wu M.B. McGechan N. McRoberts J.A. Baddeley C.A. Watson 《Ecological modelling》2007,200(3-4):343-359
It is an ongoing challenge to develop and demonstrate management practices that increase the sustainability of agricultural systems. Soil carbon and nitrogen dynamics directly affect soil quality, crop productivity and environmental impacts. Root systems are central to the acquisition of water and nutrients by plants, but are also a major pathway for the inputs of carbon and nutrients to soil. The complexity of both biotic and abiotic interactions, combined with stochastic changes in root architecture, makes it difficult to understand below-ground dynamics on the basis of experimentation alone. The integration of dynamic models of above-ground growth, three-dimensional root system demography, and interactions between plants and the environment, into one single model is a major challenge because of the complexity of the systems.In order to understand the interaction between a plant and the environment, it is advantageous to develop a model framework to integrate submodels that simulate various plant and environmental components. The objective of this paper is to outline a mechanistic and process-based model, which is capable of simulating interactions among environmental conditions around plants, plant growth and development, nitrogen and carbon cycles, with a three-dimensional root system submodel as an interface.The model presented in this paper is a mixed dimensional, multi-layer, field scale, weather-driven and daily time-step dynamic simulation model. The current version includes a plant growth and development component, a nitrogen cycling component, a carbon cycling component, plus a soil water component that includes representation of water flow to field drains as well as downwards through the soil layers, together with a heat transfer component. The components themselves and linkage among components are designed using object-oriented techniques, which makes the model robust, understandable and reusable. The components are implemented in the C++ programming language, and inputs and outputs of all components are organised as a database in either Microsoft® SQL Server 2000, Access 2000 or MySQL5.0. Root architecture is visualised by using the OpenGL graphics system. Preliminary validation with two separate experimental datasets shows that the model can reasonably simulate root systems, nitrogen cycling, water movement and plant growth. 相似文献
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The growth-differentiation balance hypothesis (GDBH) predicts changes in susceptibility of plants against herbivores with changing resource availability. In the presented study we tested the validity of the GDBH for trees infected with a root pathogen. For this purpose Fagus sylvatica seedlings grown under different atmospheric CO2- and soil nitrogen regimes were infected with the root pathogen Phytophthora citricola. High nitrogen supply increased total biomass of beech regardless of the CO2-treatment, whereas elevated CO2 enhanced biomass only in the high nitrogen treatment. The responses of beech under the different growing regimes to the Phytophthora root infection were not in line with the predictions of the GDBH. Enhanced susceptibility of beech against P. citricola was found in seedlings grown under elevated CO2 and low nitrogen supply. Fifteen months after inoculation these plants were characterized by enhanced water use efficiency, by altered root-shoot ratios, and by enhanced specific root tip densities. 相似文献
467.
The role of radial oxygen loss and root anatomy on zinc uptake and tolerance in mangrove seedlings 总被引:1,自引:0,他引:1
H. Cheng N.F.Y. Tam S.Y. Li Z.H. Ye 《Environmental pollution (Barking, Essex : 1987)》2010,158(5):1189-1196
Root anatomy, radial oxygen loss (ROL) and zinc (Zn) uptake and tolerance in mangrove plants were investigated using seedlings of Aegiceras corniculatum, Bruguiera gymnorrhiza and Rhizophora stylosa. The results revealed that B. gymnorrhiza, which possessed the ‘tightest barrier’ in ROL spatial patterns among the three species studied, took up the least Zn and showed the highest Zn tolerance. Furthermore, zinc significantly decreased the ROL of all three plants by inhibition of root permeability, which included an obvious thickening of outer cortex and significant increases of lignification in cell walls. The results of SEM X-ray microanalysis further confirmed that such an inducible, low permeability of roots was likely an adaptive strategy to metal stress by direct prevention of excessive Zn entering into the root. The present study proposes new evidence of structural adaptive strategy on metal tolerance by mangrove seedlings. 相似文献
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深圳市平湖华宝(集团)有限公司采用曝气一两级过滤工艺进行地下水除铁除锰的处理,出水的各项指标均达到国家生活饮用水卫生标准(GB5749-85),吨水处理成本为0.31元。该工艺运行稳定,投资运行费用低,具有较好的经济效益。 相似文献