Institute of Soil and Water Conservation,Chinese Academy of Sciences and Ministry of Water Resources
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退耕还林工程对河南省森林地上碳储量的影响
No full text退耕还林工程作为中国重要的植被恢复工程， 其碳汇能力巨大。 基于河南省退耕还林实施期间河南省森林
资源清查数据（ 1998－2003 年， 2003－2008 年， 2008－2013 年）， 利用生物量转换因子连续函数法， 估算河南省森林
及人工林的碳储量， 同时利用 2000－2012 年河南省退耕还林工程逐年造林树种和面积， 估算退耕还林所种树木的
碳储量。 结果表明： 河南省森林面积、 蓄积、 碳储量和碳密度分别从 1998 年的 149.77×10 4 hm 2 ， 5 258.50×10 4
m 3 ， 30.49 Tg 和 20.36 Mg · hm －2 增加到 2013 年的 305.36×10 4 hm 2 ， 17 094.56×10 4 m 3 ， 91.02 Tg 和 29.81 Mg · hm －2 ， 其
中人工林面积、 碳储量、 碳密度增幅较大。 人工林碳储量占林分总碳储量的比例由 1998 年的 29.26% 提高到 2013
年的 58.46% 。 人工林在河南省森林碳汇中发挥着越来越重要的作用， 是河南省森林碳汇的主要贡献者， 这主要归
因于退耕还林工程的实施引起人工林碳储量的增加。 2003 ， 2008 和 2013 年退耕还林工程碳储量分别占森林总碳储
量的 1.58% ， 15.40% 和 30.95% 。 河南省实施退耕还林工程具有较大的碳汇能力。 </p
土壤团聚体对泥沙沉降速度的影响
No full text坡面侵蚀泥沙是既有单粒，也含有团聚体颗粒的混合体，其沉降速度是研究泥沙运移和沉积过程的重要基
础。为研究团聚体对泥沙沉降速度的影响，选用我国5 种典型侵蚀土壤( 黄绵土、褐土、红壤、黑土和紫色土) ，每种
土壤分别做分散( 试验时仅单粒) 和未分散( 试验时含团聚体) 2 种处理，用MBWT( 改进底部取样) 沉降管进行沉降
试验测得沉速分布，通过对比分析确定团聚体对泥沙沉降速度的影响。研究结果表明: 团聚体对泥沙的沉降速度
具有显著增大作用; 对于5 种试验土壤，团聚体对泥沙沉速的增大影响均表现为，对小粒径泥沙颗粒的影响大于大
粒径; 在不同土壤类型之间，团聚体对泥沙沉速的增大作用表现为: 紫色土＞ 黑土＞ 红壤＞ 褐土＞ 黄绵土; 土壤颗
粒( 包括土壤矿质颗粒以及团聚体) 性质特征不同是团聚体对沉速影响不同的主要原因。在土壤特征参数当中，团
聚体质量加权粒径与团聚度能够较好地反映团聚体对泥沙沉速的影响大小。沉速增率与团聚体质量加权粒径和
团聚度有显著的线性相关关系。将团聚体的影响考虑到泥沙沉降过程中，对了解侵蚀泥沙的运动规律，研究土壤
侵蚀过程机理，构建土壤侵蚀过程模型具有重要意义。</p
毛乌素沙地固沙林发育过程中土壤 有机碳库稳定性特征
No full text为揭示固沙林发育过程中土壤固碳效应与有机碳库稳定性特征，基于时空替代法，
采集陕北毛乌素沙地治沙区从半固定沙地到林龄分别为 22、32、53 年乔木和灌木林地表层土
壤，分析了土壤总有机碳、氧化活性碳和惰性有机碳含量，以及矿化碳排放、分解比例的变异
特征．结果表明: 相比半固定沙地，22 ～ 53 年灌木和乔木林土壤总有机碳增幅来自惰性碳，分
别为 3．5 ～ 6．2 和 3．2 ～ 7．7 g·kg－1，来自氧化活性碳的分别为 2．8 ～ 3．4 和 1．3 ～ 2．8 g·kg－1，并且
灌木和乔木林土壤氧化活性碳所占比例未发生显著变化，分别维持在 37．0%和 26．8%，但土样
经恒温培养 60 d 后，该比例分别下降至 25．7%和 17．4%．培养结束时，
2 种林地 22 ～ 53 年土壤
有机碳矿化率无显著差异; 所有固沙林样地矿化碳的损失有 76．9% ～ 98．7%来自于氧化活性
碳，仅 1．3% ～ 23．5%来自于惰性碳．与最高碳分解速率相比，土壤碳累积释放量与 β-葡萄糖苷
酶、脱氢酶活性的相关性更强，但酶活性在 32 ～ 53 年林地无显著差异．综上，随着固沙林林龄
增加，土壤有机碳趋向少排多存碳的稳定性特征，乔木固沙林固碳效果优于灌木固沙林．</div
Effects of vegetation and rainfall types on surface runoff and soil erosion on steep slopes on the Loess Plateau, China
No full textIt is widely recognized that vegetation restoration plays a key role in controlling soil erosion in China's Loess Plateau. However, the effects of vegetation types on soil erosion on steep slopes of the Loess Plateau are not yet fully understood. In this study, we carried out our experiments on surface runoff and soil loss monitoring at nine runoff plots with different vegetation types over a nine-year period from 2008 to 2016 to evaluate the effects of vegetation and rainfall on soil erosion. We classified forty-three rainfall events into three rainfall types based on a rainfall concentration index and further analyzed the sensitivities of the runoff and soil loss to these rainfall types. The results indicated that the grassland (Bothriochloa ischaemwn L.) and shrubland (Sea-buckthom) with high ground cover had a lower runoff depth and soil loss compared to the forestlands with poor ground cover with an average reduction of 50% in annual runoff depth and 92% in annual soil loss. Comparison of the mean runoff coefficient and soil loss in the three rainfall types demonstrated that rainfall events with high intensity and short duration caused more surface runoff and soil loss under all vegetation types. A power function fitted well in the runoff-soil loss relationship and the result showed that the grassland and shrubland had a smaller magnitude term which reflects less soil susceptibility to erosion. The research implies that the ground cover is an important factor in controlling soil and water loss and vegetation measures with high ground cover should be strongly recommended for soil erosion control on the Loess Plateau. It is helpful for vegetation restoration strategy and conserving soil and water on steep slopes of this area
The mineralization and sequestration of organic carbon in relation to agricultural soil erosion
No full textThe coupling of soil erosion (especially interrill erosion by water) and the dynamics of soil organic carbon (SOC) in agricultural landscapes has been widely studied over the past two decades. To date, however, the role of soil erosion in global C cycle remains a topic of debate. Numerous questions remain to be addressed before determining the C sink/source effect of soil erosion, especially for the mineralization and sequestration of eroded SOC upon erosion, transport and deposition. In this review, we provide a comprehensive cross-disciplinary review on SOC mineralization and sequestration at sites of erosion, along the transport pathway and at depositional sites. The current state of knowledge on the impacts of erosion-induced soil aggregate breakdown and formation, removal of SOC from eroding sites and deep burial of SOC at depositional sites on the mineralization and sequestration of SOC are presented. Furthermore, we provide an overview of the conceptual relations between soil biological properties (microbial abundance, species diversity, community composition and enzyme activity) and the mineralization and sequestration of SOC in eroded agricultural landscapes, which are often overlooked by previous research and reviews. The comprehensive understanding of physical, chemical and biological mechanisms affecting the mineralization and sequestration of eroded SOC provides important insights to balance the global carbon budget and finally holds the answer on the carbon sink/source controversy
Potential land use adjustment for future climate change adaptation in revegetated regions
No full textTo adapt to future climate change, appropriate land use patterns are desired. Potential natural vegetation (PNV) emphasizing the dominant role of climate can provide a useful baseline to guide the potential land use adjustment. This work is particularly important for the revegetated regions with intensive human perturbation. However, it has received little attention. This study chose China's Loess Plateau, a typical revegetated region, as an example study area to generate the PNV patterns with high spatial resolution over 2071-2100 with a process-based dynamic vegetation model (LPJ-GUESS), and further investigated the potential land use adjustment through comparing the simulated and observed land use patterns. Compared with 1981-2010, the projected PNV over 2071-2100 would have less forest and more steppe because of drier climate. Subsequently, 25.3-55.0% of the observed forests and 79.3-91.9% of the observed grasslands in 2010 can be kept over 2071-2100, and the rest of the existing forested area and grassland were expected to be more suitable for steppes and forests, respectively. To meet the request of China's Grain for Green Project, 60.9-84.8% of the existing steep farmland could be converted to grassland and the other for forest. Our results highlight the importance in adjusting the existing vegetation pattern to adapt to climate change. The research approach is extendable and provides a framework to evaluate the sustainability of the existing land use pattern under future climate. (c) 2018 Elsevier B.V. All rights reserved
Phytoextraction of rhenium by lucerne (Medicago sativa) and erect milkvetch (Astragalus adsurgens) from alkaline soils amended with coal fly ash
No full textCoal fly ash (CFA) is an industrial waste generated in huge amounts worldwide, and the management of CFA has become an environmental concern. Recovery of valuable metals from CFA is one of the beneficial reuse options of CFA. Rhenium (Re) is one of the rarestmetals in the Earth's crust and one of the most expensive metals of strategic significance in the worldmarket. A CFA at the Jungar Thermal Power Plant, InnerMongolia, China, contains more Re than two alkaline soils in the surrounding region. Pot experimentswere undertaken to grow lucerne (Medicago sativa) and erect milkvetch (Astragalus adsurgens) in a loessial soil and an aeolian sandy soil amended with different rates (5%, 10%, 20%, and 40%) of CFA. The results show that plant growth was considerably enhanced and Re concentration in plants was significantly increased when CFA was applied to the alkaline soils at rates of <= 20%; while in some cases plant growth was also markedly enhanced by the 40% CFA treatment, which increased plant Re concentration the most of all treatments. Both lucerne and erect milkvetch showed potential for phytoextracting Re from CFA-amended alkaline soils. Using CFA for soil amendment not only offers a potential solution for the waste disposal problem of CFA, but the phytoextraction of Re by both lucerne and erectmilkvetchmay also bring an economic profit in the future. (C) 2018 Elsevier B.V. All rights reserved
Effect of Catch-Can Spacing on Calculation of Sprinkler Irrigation Application Uniformity
No full textSprinkler irrigation application uniformity is an important indicator for sprinkler irrigation system design, which can be expressed by the Christiansen uniformity coefficient (CU). The calculated accuracy of CU is closely related with catch-can spacing and grid size. In theory, the smaller the catch-can spacing and grid size are, the more accurate the calculation of CU is. However, smaller catch-can spacing needs more labor in water distribution measurement, and smaller grid size needs more computer runtime to calculate CU. In order to recommend the proper catch-can spacing and grid size, an experiment is carried out to obtain four different water distribution patterns, and data characteristics for water distribution with various catch-can spacing and the effect of catch-can spacing and grid size on CU are studied in the paper. The results show that CU is overestimated for the larger catch-can spacing, especially when the distribution of water for the pattern is non-uniformity. CU changes very little within a certain catch-can spacing and grid size for all the four patterns. Considering the accuracy of CU calculation, labor cost, and the computational runtime, the recommended catch-can spacing is 1.96m for pattern I, 0.92m for patterns III and IV, and the recommended grid size in the calculation of CU is 1.25, 1.0, and 0.5m for patterns I, III, and IV, respectively
Soil water storage compensation potential of herbaceous energy crops in semi-arid region
No full textLarge-scale vegetation construction has generally led to soil desiccation in arid and semi-arid regions. Energy crops with high biomass and water use efficiency are generally beneficial to agriculture and the environment. It is necessary to understand how to maintain the dynamic balance of soil moisture and biomass production on herbaceous energy croplands. In this study, soil moisture data at different depths of soil were obtained from long-term field observations for two energy crops, i.e., Panicum virgatum and Miscanthus sinensis, and a forage crop-Medicago saliva. Relative aridity of the soil and plant biomass were compared among different vegetation types, transects, and cultivation years. Medicago sativa soil was severely, even extremely, desiccative with increasing cultivation years, whereas there was nearly no desiccation in the soil of energy crops. The values of compared soil water storage compensation indexes in deep soil layers were higher than those in shallow soil layers, with the evaluated soil water storage compensation index being the smallest in the 40-80 cm layer. Energy crops had significantly higher aboveground biomass, mostly exhibiting more than 2.6 kg m(-2), while the aboveground biomass of M. saliva was only above 0.5 kg m(-2). Furthermore, the water use efficiencies of energy crops were obviously higher than that of M. saliva (P < 0.05). Our results indicated that deep soil moisture conditions were mainly determined by field crop types. Energy crops may be suitable candidates for compensating soil water storage and maintaining high biomass production in semi-arid regions