黄土高原苹果树生育期树干液流特征及其影响因子研究     

曹铨  王自奎  来兴发  沈禹颖 《干旱地区农业研究》2023,(4):267-274

为探究黄土高原半干旱区苹果树生育期液流特征及其与影响因子之间的关系,于2018年果树生育期利用热扩散式液流探针(TDP)对‘秦冠’苹果树(Malus pumila M. cv Qinguan)液流进行了连续观测,同步测定了果园土壤水分、苹果树叶面积指数、大气温度、大气湿度、太阳辐射和风速等指标,并计算空气水汽压差。结果表明：苹果树在萌芽开花期、幼果期、果实膨大期及果实成熟期的平均液流速率分别为0.85、1.34、1.53、0.82 mm·d^-1,果实膨大期液流速率较高。液流速率具有明显的昼夜波动性,不同生育时期夜间液流量约占总液流量的11.54%～19.22%。茎流计测定的苹果树生育期总液流量为264.14 mm,其中夜间累计液流量为35.60 mm。全生育期内苹果树的液流速率与太阳净辐射、大气温度、水汽压差和叶面积指数均呈极显著正相关关系,与风速和大气湿度呈负相关关系。萌芽开花期、幼果期及果实成熟期,水汽压差是影响果树液流速率的关键因子;而在果实膨大期,太阳净辐射是影响果树液流速率的关键因子。果树液流速率与0～20 cm土层土壤含水量相关性不显著,与20～160...  相似文献   

Effects of plateau pika on the relationship between plant species diversity and functional diversity in alpine meadow北大核心CSCD     

段媛媛  张静  王玲玲  刘彩凤  王乙茉  周俗  郭正刚 《草业学报》2022,31(11):25-35

The relationship between plant species diversity and functional diversity in grassland will change with environmental changes. The plateau pika （Ochotona curzoniae） has an effect on the hydrothermal process of alpine meadow in its nesting area. However,it is not clear whether the disturbance of plateau pika effects the relationship between plant species diversity and functional diversity in alpine meadow. A random stratified and paired design was used to select plots in Luqu county in Gansu Province,and Qilian and Gonghe Counties in Qinghai Province and a field survey was conducted to investigate the effects of plateau pika disturbance on the relationship between plant species diversity and functional diversity of the alpine meadow. It was found that plateau pika disturbance significantly increased the plant species richness index and the species diversity index but did not significantly affect the species evenness index. Plateau pika disturbance significantly increased plant functional richness index （P< 0.05） but had no significant effect on the plant functional evenness index or the functional divergence index. With plateau pika disturbance effects,the relationship between plant functional richness index and species richness index changed from a logarithmic function to a quadratic function,and the relationship between plant functional evenness index and species evenness index changed from non-significant to significantly positive. In addition, positive correlations between functional richness index and species richness index,and functional richness index and species diversity index were significantly decreased,as were negative correlations between functional divergence index and species richness index,and functional divergence index and species diversity index were significantly decreased. The findings of this study provide basic information for understanding the mechanism of species coexistence of plant communities under plateau pika disturbance and help understanding of how plant diversity effects in an alpine meadow ecosystem function under plateau pika disturbance. © 2022 Editorial Office of Acta Prataculturae Sinica. All rights reserved.  相似文献   

基于Meta分析的放牧对黄土高原草地生态系统的影响     

贾涛涛  廖李容  王杰  刘国彬  张超 《草地学报》2022,30(10):2772-2781

为明确放牧对黄土高原草地生态系统的整体影响,本文对39篇相关文献进行Meta分析,探讨了放牧对黄土高原草地植被、土壤理化性质和土壤微生物的影响,并进一步分析了影响其放牧效应的相关因素。结果表明：放牧对黄土高原草地植物多样性、土壤细菌丰度和放线菌丰度以及土壤微生物总丰度没有显著影响,但却显著降低了草地的生产力和土壤碳氮磷养分,明显增加了土壤容重、pH值和土壤真菌相对丰度;草地生态系统对放牧的响应受放牧强度和年平均降水量的影响,中度放牧有利于维持植物地下部分的生长,轻度放牧有利于维持土壤水分和养分;在年平均降雨量较低(<300 mm)的干旱地区,植物可能具有更好抵抗放牧干扰的能力,放牧对土壤养分的扰动不严重,在年平均降雨量较高(>400 mm)的湿润地区,放牧更容易改变土壤微生物的群落组成。  相似文献   

单播措施下三江源区高寒退化草地恢复效果评估     

张小芳  张春平  杨增增  李彩弟  杨晓霞  刘文亭  俞旸  董全民 《草地学报》2022,30(10):2834-2844

本研究以青海省海南州贵南县森多乡和果洛州玛沁县大武镇针对重度退化草地建植的单播人工草地为研究对象,研究了不同区域恢复草地的植被生物量、群落结构、物种多样性和土壤有机碳变化特征,并采用CVOR综合指数评价单播措施在不同区域的恢复效果和健康状况,为指导高寒草地恢复及人工草地的后续管理提供理论依据。主要得到以下研究结果：研究区不同建植期草地地上生物量、物种多样性、植物功能群组成和土壤有机碳含量存在显著差异。单播措施显著提高了不同区域的草地地上生物量和禾本科牧草所占比例,降低了物种多样性指数,土壤有机碳呈现不同的变化规律。此外,对不同区域恢复草地进行健康评价的结果发现,单播后,年度内研究区域的健康等级均处在健康和警戒状态。综上所述,人工草地的建植能够有效恢复黑土滩退化草地。  相似文献   

Econometric analysis of the determinants of adoption of rainwater harvesting and supplementary irrigation technology (RHSIT) in the semiarid Loess Plateau of China   总被引：1，自引：0，他引：1  

Xue-Feng He  Huhua Cao  Feng-Min Li 《Agricultural Water Management》2007

Using a binary logistic regression model, this paper evaluates the determinants of farmers’ decisions to adopt rainwater harvesting and supplementary irrigation technology (RHSIT) and its elasticity of adoption in the rain-fed farming systems, based on a survey of 218 farmers in the semiarid areas of Loess Plateau in 2005. The results indicate that 12 variables are significant in explaining farmers’ adoption decisions. Farmers’ educational background, active labor force size, contact with extension, participation in the Grain-for-Green project, and positive attitudes towards RHSIT are some of the variables that have significantly positive effects on adoption of RHSIT, while farmer's age and distance from water storage tanks to farmers’ dwellings have significantly negative correlation with adoption. The probability of adoption also increases with increased targeting of institutional variables: credit obtained, assistance obtained, and technical training received. Farmers in villages that have more erosion problems are more likely to adopt RHSIT. Besides, the model indicates that a 1 unit increase in the diversity of irrigated crops grown by a household, especially high-value crops, results in a 6.98 times increase in the probability of RHSIT adoption. Variables such as family size, off-farm activity, level of family income, risk preference, and land tenure do not significantly influence adoption. This information will help prioritize the factors that affect adoption decisions and provide insight on pathways to increase the adoption of RHSIT.  相似文献   

黄土高原撂荒草地土壤碳库对两年增温增雨的响应     

王兴  钟泽坤  王佳懿  简俊楠  杨改河  任成杰  韩新辉 《土壤学报》2023,60(2):523-534

阐明暖湿的气候趋势下黄土高原土壤有机碳库不同活性组分和碳库稳定性的变化特征,对脆弱生态区碳库的可持续发展以及评估区域生态效益具有重要意义。以黄土丘陵区自然撂荒草地为研究对象,人工模拟增温和增雨,分析了在增温（W）、增雨（P50%）及其交互作用（WP50%）下植被群落变化特征、土壤有机碳库组分含量、碳库组分的分配比例以及碳库稳定性的变化特征。结果发现：（1）增雨显著增加了植被丰富度指数,而增温和增温增雨显著降低了植被丰富度指数。（2）增雨处理下土壤有机碳、酸解有机碳、易氧化有机碳、溶解性有机碳含量及分配比例在两个取样年均显著高于对照;增温增雨处理则进一步增加了土壤易氧化有机碳和微生物生物量碳含量以及分配比例。相关性分析表明,土壤有机碳与各个活性碳组分之间存在显著相关性。（3）增温增雨处理下土壤碳库活度、碳库活度指数以及碳库管理指数均高于其他处理。酸解有机碳和微生物生物量碳的敏感指数在气候变化处理下相对较高。综上所述,暖湿化的气候背景下黄土丘陵区撂荒草地土壤有机碳、有机碳活性组分含量和分配比例以及碳库稳定性显著提高,有助于碳库良性发展,酸解有机碳和微生物生物量碳可作为未来土壤有机碳变化的重...  相似文献   

雨型和坡长对侵蚀泥沙粒径特征的影响   总被引：1，自引：0，他引：1  

郭凯  李玄添  张风宝    申楠    杨明义   《水土保持研究》2023,30(2):50-57,66

为揭示降雨和坡长对侵蚀泥沙粒径特征的影响,以不同坡长野外观测试验小区为对象,结合82场降雨资料,以降雨量(P,mm)、最大30 min雨强(I₃₀,mm/h)和降雨侵蚀力[R,MJ·mm/(hm²·h)]为降雨特征指标,利用系统聚类法进行雨型划分(A雨型：大雨量、高雨强、高侵蚀力;B雨型：中雨量、小雨强、中等侵蚀力;C雨型：低雨量、中雨强、中低等侵蚀力),分析了11场降雨事件中侵蚀泥沙的粒径分布特征。结果表明：(1)研究区侵蚀泥沙粒径特征受不同雨型影响,有效黏粒和最终黏粒含量在C雨型下最高,有效砂粒和最终砂粒含量在B雨型下最高,而有效粉粒和最终粉粒含量分别在A和C雨型下最高。(2)坡长对侵蚀泥沙粒径特征的影响存在临界坡长效应(14 m),小于临界坡长时,黏粒级和粉粒级颗粒含量随坡长增加而降低;超过临界坡长后,黏粒级和粉粒级颗粒含量随坡长增加而增加,该效应在最终粒径下更为显著。(3)有效砂粒输移形式受雨型和坡长影响较大,在B雨型下主要以团粒形式输移,在A,C雨型下达临界坡长时以单粒形式输移。侵蚀泥沙的有效粒径颗粒比原坡面土壤细,而最终粒径颗粒则...  相似文献   

基于机器学习的沟谷地貌识别模型对比——以黄土高原典型流域为例     

范天程  汪珍亮  李云飞  贾云飞  袁可  赵建林 《水土保持学报》2023,37(4):205-213

探索沟谷地貌空间分布与环境控制特征之间的联系并构建沟谷地貌准确提取模型,对大尺度范围沟谷提取具有重要意义。基于人工提取黄土高原典型流域沟谷地貌样本,结合不同时期的Landsat8 OLI影像数据和DEM数据,建立随机森林模型确定黄土高原沟谷地貌提取最佳影像时期和最佳组合特征,基于最优模型参数,对比其与支持向量机和人工神经网络沟谷提取模型效果,验证模型泛化能力。结果表明:(1)黄土高原沟谷提取的最佳影像时期为12月,最佳组合特征集为Red、Blue、H、SWIR1、PNT、Coastal、GLCM4和NIR;(2)3种方法提取测试区域的沟谷空间分布一致,从定性和定量角度进行比较,随机森林模型提取效果最好,验证样区平均总体精度为80.48％,相较于支持向量机模型和人工神经网络模型分别提高4.00和8.63个百分比;(3)测试区域中,沟谷地貌面积约占总面积的56.91％,且呈现西北至东南方向逐渐集中的特点。研究表明随机森林模型在黄土高原地区高精度沟谷地貌识别研究中综合表现最佳,可大范围推广。  相似文献   

Decoupling effects of driving factors on sediment yield in the Chinese Loess Plateau     

《国际水土保持研究(英文)》2023,11(1):60-74

Investigations of runoff and sediment yield changes and their relationships with potential driving factors provide good insights for understanding the mechanisms of hydrological processes. This study attempted to present a comprehensive investigation on the spatiotemporal variations of sediment yield in the Loess Plateau using continuous observed data at 46 hydrological stations during 1961–2016, and its responses to changes of precipitation, land use/cover and vegetation cover were analyzed by using the Partial Least Squares-Structural Equation Model (PLS-SEM). The results indicated that sediment yield reduced pronouncedly during 1961–2016 in the Loess Plateau, and 77.9% of this variation was explained by the combined effects of precipitation, land-use change, vegetation dynamics and runoff reduction. Indirect effects of precipitation, land-use change, and vegetation cover on sediment yield were 0.242, ?0.528 and ?0.630 (P < 0.05), respectively, and direct effect of runoff on sediment yield was 0.833 (P < 0.05). According to the Pearson Correlation Coefficient, the strongest positive correlation existed between annual sediment yield and runoff (r = 0.88, P < 0.05), followed by vegetation cover (r = ?0.47, P < 0.05) and land-use change (i.e. forest land and grassland) suggesting their significant trapping effects on soil erosion. However, lower correlations were examined between sediment yield and precipitation indices (?0.14<r < 0.34), and a relatively higher relationship was examined between sediment yield and heavy rainfall (P₂₅) (r = 0.34). Overall, changes in runoff and land-use/vegetation cover well explained variations in sediment yield in the Loess Plateau. The findings are expected to provide scientific and technical support for future soil and water conservation planning in the Loess Plateau, and are valuable for sustainable water resources and sediment load management in the Yellow River Basin.  相似文献   

137Cs tracing of the spatial patterns in soil redistribution,organic carbon and total nitrogen in the southeastern Tibetan Plateau     

《国际水土保持研究(英文)》2023,11(1):86-96

The southeastern Tibetan Plateau, which profoundly affects East Asia by helping to maintain the stability of climate systems, biological diversity and clean water, is one of the regions most vulnerable to water erosion, wind erosion, tillage erosion, freeze–thaw erosion and overgrazing under global climate changes and intensive human activities. Spatial variations in soil erosion in terraced farmland (TL), sloping farmland (SL) and grassland (GL) were determined by the ¹³⁷Cs tracing method and compared with spatial variations in soil organic carbon (SOC) and total nitrogen (total N). The ¹³⁷Cs concentration in the GL was higher in the 0–0.03 m soil layer than in the other soil layers due to weak migration and diffusion under low precipitation and temperature conditions, while the ¹³⁷Cs concentration in the soil layer of the SL was generally uniform in the 0–0.18 m soil layer due to tillage-induced mixing. Low ¹³⁷Cs inventories appeared at the summit and toe slope positions in the SL due to soil loss by tillage erosion and water erosion, respectively, while the highest ¹³⁷Cs inventories appeared at the middle slope positions due to soil accumulation under relatively flat landform conditions. In the GL, the ¹³⁷Cs data showed that higher soil erosion rates appeared at the summit due to freeze–thaw erosion and steep slope gradients and at the toe slope position due to wind erosion, gully erosion, freeze–thaw erosion and overgrazing. The ¹³⁷Cs inventory generally increased from upper to lower slope positions within each terrace (except the lowest terrace). The ¹³⁷Cs data along the terrace toposequence showed abrupt changes in soil erosion rates between the lower part of the upper terrace and the upper part of the immediate terrace over a short distance and net deposition on the lower and toe terraces. Hence, tillage erosion played an important role in the soil loss at the summit slope positions of each terrace, while water erosion dominantly transported soil from the upper terrace to the lower terrace and resulted in net soil deposition on the flat lower terrace. The SOC inventories showed similar spatial patterns to the ¹³⁷Cs inventories in the SL, TL and GL, and significant correlations were found between the SOC and ¹³⁷Cs inventories in these slope landscapes. The total N inventories showed similar spatial patterns to the inventories of ¹³⁷Cs and SOC, and significant correlations were also found between the total N and ¹³⁷Cs inventories in the SL, TL and GL. Therefore, ¹³⁷Cs can successfully be used for tracing soil, SOC and total N dynamics within slope landscapes in the southeastern Tibetan Plateau.  相似文献