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1.
Black locust (Robinia pseudoacacia) has been widely planted in the Chinese Loess Plateau for soil and water conservation as an important forest species. This study examined variations in topsoil organic C (OC), total N and P (TN and TP), available N, P and K (AN, AP and AK), and soil microbial biomass C, N and P (SMBC, SMBN and SMBP) contents and the activity of urease (URE), α-amylase (ALA), alkaline phosphatase (ALP), catalase (CAT), saccharase (SAC), polyphenol oxidase (PPO) and cellulase (CEL) in loessial soil of black locust with an age sequence of 5, 10 15, 20, 25, 30, 40 and 50 years in Zhifanggou watershed (8.27 km2), Shaanxi Province, Northwest China. Also cultivated fields and 80-year Chinese arborvitae (Platycladus orientalis) were selected for the comparison. The results showed that soil chemical properties, microbial biomasses and soil enzyme activities varied with the restoration age. After 50-year growth of black locust, OC, TN, AN, TP, AK, SMBC, SMBN, SMBP, URE, ALP, SAC and CEL in soil increased by 262, 193, 345, 22, 36, 210, 136, 85, 90, 108, 288 and 36%, respectively, while PPO decreased by 31%. Soil chemical properties of TN and soil microbial biomass of SMBC were linearly correlated with soil enzymes of URE, ALP and SAC. Moreover, nitrogen fixation of black locusts was not evident before it became mature, but more evident after it reached maturity. The results confirmed that black locusts have long-term benefits on the improvement of soil properties as exotic species on the Loess Plateau for the soil properties under black locusts were greatly improved compared to cultivated fields.  相似文献   

2.
To improve the ecological environment in China, the Chinese government implemented a country-wide ecological protection and reforestation project (namely the “Grain for Green Project”) in 1999 to return cultivated land with slopes of 25° or more to perennial vegetation. Vegetation restoration reduces soil erosion mainly by changing the soil physical properties. Different vegetation restoration methods might produce different impacts on soil physical properties. In this study, two vegetation restoration methods (i.e., natural restoration and artificial restoration) were compared on abandoned farmland in the typically hilly and gullied areas of the Loess Plateau of Northwest China. In the natural restoration method, the farmland was abandoned to natural vegetation succession without irrigation, fertilization or other artificial disturbances. In the artificial restoration method, the farmland was planted with black locust (Robinia pseudoacacia L.) and watered and cultivated for the first two years. Three soil physical properties (i.e., soil moisture, bulk density and aggregation) were investigated under the two vegetation restoration methods. The results showed that the soil moisture and soil bulk density were higher under artificial restoration than under natural restoration within the first three years of vegetation restoration. By the fourth year, the soil moisture and soil bulk density were higher under natural restoration than under artificial restoration. For the stability of soil aggregates?>?0.25 mm, the soil aggregates in the 0-20 cm soil layer were more stable under artificial restoration than under natural restoration, while the results were the opposite for the 40-60 cm soil layer. Overall, the soil physical properties were continuously improved during the restoration of vegetation on abandoned farmland. In choosing between vegetation restoration methods, natural restoration is preferable to artificial restoration, but artificial intervention is needed during the first three years.  相似文献   

3.
基于水土保持的流域生态环境需水研究   总被引：4，自引：0，他引：4  
针对现有生态环境需水量的计算主要基于现状而导致其实用性不足的特点,提出了根据流域或区域对生态环境功能的需求来确定其生态建设规模并计算其生态环境需水量的思想。以位于黄土高原的安塞纸坊沟流域为例,针对该流域以水土流失为首要生态环境问题的特点,在已有的土壤侵蚀与土地利用结构关系研究的基础上,基于水土保持目标确定土地利用结构,进而计算出该流域的生态环境需水量,并对不同土地利用情景以及不同水土保持目标进行了对比分析。研究表明,综合考虑水土保持效益与生态环境用水代价,纸坊沟流域以允许土壤流失量1 000 t/(km2·a)为目标为宜,此时该流域生态环境需水量约为1.77×106 m3,占该流域年降水总量的39.0%。通过与基于生态系统现状的计算结果相比较,说明提出的思想更为合理。  相似文献   

4.
The Horqin Sandy Land is one of the most severely desertified regions in northern China. Plant communities and soil conditions at five stages of grassland desertification (potential, light, moderate, severe and very severe) were selected for the study of vegetation pattern variation relating to soil degradation. The results showed that vegetation cover, species richness and diversity, aboveground biomass (AGB), underground biomass, litter, soil organic carbon (C), total nitrogen (N), total phosphorus (P), electrical conductivity, very fine sand (0.1–0.05 mm) content and silt (0.05–0.002 mm) content decreased with the desertification development. Plant community succession presented that the palatable herbaceous plants gave place to the shrub species with asexual reproduction and sand pioneer plants. The decline of vegetation cover and AGB was positively related to the loss of soil organic C and total N with progressive desertification (P < 0.01). The multivariate statistical analysis showed that plant community distribution, species diversity and ecological dominance had the close relationship with the gradient of soil nutrients in the processes of grassland desertification. These results suggest that grassland desertification results in the variation of vegetation pattern which presents the different composition and structure of plant community highly influenced by the soil properties.  相似文献   

5.
采集了福建云霄漳江口米草入侵下红树林自然湿地保护区内红树林群落、米草群落、红树林—米草交互群落以及光滩的剖面土壤样品,分析了土壤的总养分库、有效养分库及微生物活性等指标。结果表明,不同植被群落下土壤理化性质均存在明显差异。土壤有机质、全氮、全磷、阳离子交换量和微生物生物量碳、氮在同一深度的含量变化为：红树林>红树林—米草混作>米草>光滩;土壤蔗糖酶、脲酶、磷酸酶、过氧化氢酶和多酚氧化酶等酶活性指标也表现出相似的变化趋势。从深度变化而言,上述各项土壤质量指标均随剖面深度而降低。米草入侵后土壤的各项养分指标均有明显下降,湿地土壤生态化学性质发生了明显的退化。土壤有机碳、土壤微生物生物量碳、氮含量以及土壤蔗糖酶与磷酸酶活性对滨海湿地土壤退化的反映最为强烈, 可以作为指示性指标。  相似文献   

6.
This study characterized and compared changes in vegetation condition in areas with different gradients during the past three decades across the entire Loess Plateau. For this purpose, changes in vegetation type and vegetation coverage at sites with 0 – 15° and >15° slope gradients were determined by analyzing land use data and Normalized Difference Vegetation Index (NDVI) data, respectively. The software Arc/Info 9.3, land use transformation matrix, linear regression analysis, and Mann–Kendall test were used for the data processing and analysis. Policy influences, human impacts, and climate variability were also taken into account to find the reasons for vegetation condition change. The results indicated that the “Grain-For-Green” project achieved initial success. Areas of farmland and grassland changed most extensively, and far greater areas of farmland were transformed into forest and grassland than vice versa. Moreover, the conversion of farmland to forest and grassland mainly occurred in areas where slopes exceeded 15°, while grassland was mainly changed to farmland in areas with gentle slopes. Vegetation coverage on the Loess Plateau exhibited overall increases after the implementation of “Grain-For-Green” project. Regions with sparse vegetation have declined sharply, mostly in steeply sloped areas. Vegetation coverage has increased significantly in most regions, particularly in the parts traversed by the principal sediment source of the Yellow River, which could help to control the severe soil and water losses. However, regions with sparse vegetation on the Loess Plateau still covered 71.1 % of the total area in 2010. Therefore, it is important to further increase vegetation coverage in the future.  相似文献   

7.
Zhang Zonghu 《GeoJournal》1991,24(2):195-200
The soil erosion processes in the Loess Plateau may be divided into three types: namely, waterflow erosion; gravitational erosion; wind erosion. The waterflow erosion is most widely distributed and is the main erosion action in the Loess Plateau. The main factors dominating the occurrence and development of the soil erosion in the Loess Plateau are: 1. rainfall; 2. topography; 3. vegetation; 4. soil character. The energy of erosion action depends upon the rainfall and topography, but erodiblity depends upon the vegetation and soil properties. The degree of soil erosion in the Loess Plateau changes with variations of interaction of erosion and anti-erosion measures.  相似文献   

8.
黄土高原土壤侵蚀(水蚀)多尺度过程与水土保持研究进展   总被引：5，自引：1，他引：4  
韩晓燕  钱鞠  王磊  刘芬  毛泽秦 《冰川冻土》2012,34(6):1487-1498
从产生土壤侵蚀机理出发, 分别阐述了黄土高原地区的坡面、 沟谷、 小流域、 流域尺度上的土壤侵蚀(水蚀)研究现状与取得的进展.结合平凉城南侧泾河一级支沟的纸坊沟小流域治理实践和调查, 总结黄土高原地区水土流失治理和水保措施实施的经验及其存在的不足. 建议未来的研究向着"规划性"、 "综合性"、 "量化尺度性"、 "弱化尺度性"模型的研究方向发展, 这对提高地区水土保持质量、 改善水土流失治理现状、 实现水保效益最大化目标具有重要意义.  相似文献   

9.
根据陇东黄土高塬沟壑区典型小流域——南小河沟流域1954—2014年实测降雨产沙资料,应用降雨侵蚀力偏差系数法研究不同土地利用类型及空间尺度下侵蚀产沙的雨量阈值、雨强阈值及复合阈值标准,并通过对比分析确定了最优降雨阈值标准。结果表明:① 对于林地和草地坡面小区,其雨量阈值标准平均值（21.0 mm）较裸地（8.7 mm）和农地（9.7 mm）坡面小区分别提高了141%和116%,植被措施能够显著提高降雨阈值标准。② 杨家沟林地小流域的雨量阈值标准为16.5 mm,低于布设在该流域的林地坡面小区,同时对比董庄沟草地小流域及其坡面和全坡面小区的雨量阈值标准,其大小亦为:草地坡面尺度 > 草地全坡面尺度 > 草地小流域尺度,由此可见,降雨阈值标准会随着空间尺度增大而减小。③ 降雨阈值标准综合评价结果表明,各样点最优降雨阈值标准均为P≥a或I30≥b这一复合因子标准,而在降雨单因子阈值标准中,对于农耕地和裸地坡面小区,宜采用最大30 min雨强（I30）标准;对于经过水土流失治理的下垫面,宜采用雨量（P）标准。该研究可为区域土壤侵蚀预报提供参考。  相似文献   

10.
The vegetation community succession influences soil nutrient cycling, and this process is mediated by soil microorganisms in the forest ecosystem. A degraded succession series of karst forests were chosen in which vegetation community changed from deciduous broadleaved trees (FO) toward shrubs (SH), and shrubs–grasses (SHG) in the southwest China. Soil organic carbon (SOC), total nitrogen (TN), labile organic carbon (LOC), water extractable organic matter (WEOM), microbial biomass carbon and nitrogen (MBC and MBN), bacterial and fungal diversity, as well as soil enzyme activities were tested. The results showed that SOC, LOC, MBC, MBN, and enzyme activities declined with vegetation succession, with the relatively stronger decrease of microbial biomass and functions, whereas WEOM was higher in SHG than in other systems. In addition, soil bacterial and fungal composition in FO was different from both SH and SHG. Despite positive relationship with SOC, LOC, and TN (p < 0.01), MBC, MBN appeared to be more significantly correlated to LOC than to SOC. It suggested that vegetation conversion resulted in significant changes in carbon fractions and bioavailability, furthermore, caused the change in soil microbial community and function in the forest ecosystem.  相似文献   

11.
Soil erosion is a serious global environmental problem which limits the survival and development of human beings. In our country, due to the special physical geography and socio-economic conditions, soil erosion intensity is great, which is particularly prominent in Loess Plateau region. Therefore, preventing and controlling soil erosion, as well as reducing soil erosion in Loess Plateau have become the key to solving environmental problems in the region. Soil erosion on Loess Plateau is serious, and grassland vegetation has good effects on soil and water conservation, which can improve ecological environment well. After the implementation of the project about returning farmland to grassland on Loess Plateau, the ecological benefits mainly focused on soil and water conservation benefits, soil improvement benefits, water conservation benefits and species diversity benefits, etc. Grassland vegetation has an irreplaceable role in the construction of the ecological environment on Loess Plateau. Therefore, the role of grassland in preventing soil erosion has received more and more attention. Scholars have done lots of research involved in the relationship between grassland coverage and soil erosion, impacts of grassland on hydrodynamic parameters, effects of grassland on soil properties, reduction effects of grassland on runoff and sediment, and soil erosion process on grassland slope. However, there is little research on erosion effect induced by grassland cover. This paper mainly pointed out the following questions: First, grassland cover is influenced by many factors, but the relationship with soil erosion from the dynamic mechanism is rarely discussed; Second, there is no well-developed theory of overland flow erosion at present, which limits the study of hydrodynamic parameters on grassland slope; Third, establishment of mathematical model between grassland cover and soil resistance can accelerate the quantitative analysis of grassland influence on erosion; Fourth, comprehensive analysis of influencing factors on water reduction and sediment reduction effect on grassland are insufficient; Fifth, there are not many mechanisms to analyze the erosion process of grassland slope by using the hydrodynamic characteristics of slope; sixth, research results on grassland-induced erosion are mainly focused on leading to soil dry layer and we should continue to strengthen in the future. This paper summarized the previous results, and supplemented some studies about erosion caused by grassland, then pointed out the existing problems in current research and the areas that need to be strengthened in the future, aiming at reducing soil erosion on the Loess Plateau.  相似文献   

12.
The Loess Plateau is well known to the world because of its thick loess and severe soil erosion. Loess is a highly erosion-prone soil that is considerably susceptible to water erosion. The Loess Plateau also has a long cultivation history, hence population growth, vegetation degeneration serious soil and water loss were obviously problems on Loess Plateau. This article analyzes several strategies of soil and water conservation on the Loess Plateau, such as terracing, planting trees, natural vegetation rehabilitation and construction of warp land dams. Different periods had different strategies of soil and water conservation and each strategy had its characteristics and effects. Finally, the research directions and future perspectives of the Loess Plateau were discussed, including the strategies of sustainable eco-environment of Loess Plateau in China.  相似文献   

13.
岩溶山地典型植被恢复过程中土壤理化性质及微生物特征   总被引：1，自引：0，他引：1  
探讨了岩溶山地耕地、1年退耕地、灌草地、15年侧柏疏林地、25年侧柏次生林地植被恢复过程中土壤理化性质和微生物特征的变化。结果表明土壤随着植被恢复的进行,容重先升高后降低,总孔隙度与之相反;各恢复阶段（退耕地、灌草地、疏林地、次生林地）表土＞0.25 mm水稳定性团聚体含量较耕地的增幅为5.1%～12.5%,以疏林地最高;团聚体结构破坏率依次降低,各恢复阶段较耕地降幅为34.0%～64.7%,与有机质呈负相关;全N、碱解N等肥力因子含量总体呈逐渐增加的趋势;各恢复阶段中以灌草地pH值最高;表土微生物总数先降后升,各阶段细菌占微生物总数的66.7%～93.3%,放线菌占4.2%～28.8%,同时细菌也是土壤呼吸的主要贡献者。土壤特征的差异性是地表植物组成、凋落物成分及不同指标之间综合作用的结果。   相似文献   

14.
退化喀斯特植被的恢复机理一直是近年来土壤学和生态学研究的热点。通过分析退化喀斯特植被恢复过程中土壤微生物数量、土壤生化作用强度、土壤微生物生物量,研究了贵州花江喀斯特高原生态综合治理示范区内土壤微生物活性的变化。结果表明:退化喀斯特植被恢复过程中土壤的微生物活性存在较大差异。随着退化喀斯特植被的恢复,土壤细菌、真菌、放线菌三大微生物数量及微生物总数明显上升,表现为乔木群落阶段〉灌木群落阶段〉草本群落阶段〉裸地阶段,且细菌较真菌和放线菌相比占绝对优势,其在微生物总数中分别占95．95％,93．49％,92．32％和92．48％;各主要生理类群的数量呈上升趋势,且氨化细菌〉固氮菌〉纤维素分解菌〉硝化细菌,土壤生化作用强度增强;土壤微生物生物量碳明显增加,微生物生物量碳与土壤有机碳（P〈0．01）呈显著正相关关系。土壤微生物是表征退化喀斯特植被恢复过程中土壤质量的重要特征之一,反映出随着退化喀斯特植被的恢复土壤质量也在逐渐恢复。   相似文献   

15.
李强 《地球学报》2021,42(3):417-425
土壤生物是土壤生态系统的重要组成部分,在生态系统物质循环和能量转化中占有重要的地位.为揭示土地利用方式对岩溶断陷盆地土壤生物的影响,在获取土壤理化性质及碳氮磷化学计量学特征的基础上,利用16S rRNA和18S rRNA高通量测序技术研究了弃耕地、草地、人工林和天然林等土壤细菌与真核生物的群落结构.C:N、C:P和N:P比变化规律为弃耕地<草地<人工林<天然林,土壤细菌和真核生物α多样性、互作网络表现出相反的变化规律.土壤磷、钾和钙是影响岩溶断陷盆地土壤细菌和真核生物群落结构和多样性的关键因素.RB41是决定岩溶断陷盆地土壤细菌-真核生物网络系统的关键类群.本研究结果为利用土壤生物进行石漠化治理及岩溶生态修复提供了理论基础.  相似文献   

16.
《Applied Geochemistry》2003,18(8):1241-1249
A combination of δ 13C values with C/N ratios in suspended matter has been used to examine the seasonal relationship between C4 and C3 vegetation along the Loess Plateau, NW China. The C isotopic composition of suspended organic matter in rivers, together with C/N ratios can differentiate between soil and plant material, and can be used to estimate the relative contributions of soil organic C and plant litter to the suspended matter. The relationship between C isotopic composition and C/N ratios indicates that the samples are a mixture of two end members: (1) modern soils with relatively constant δ 13C values, low C content and low C/N ratios; (2) plant litter with varying δ 13C values, high C content and high C/N ratios. The results reflect the seasonal distribution of C4/C3 vegetation within the area studied, as part of the Loess Plateau. The abundance of C4 grasses is about 20% for the current summer vegetation ecosystem in the eastern part of the Loess Plateau. Hence, the use of δ 13C values and C/N ratios of suspended matter in rivers and modern soil may be useful for reflecting seasonal distribution of C4/C3 vegetation in catchments. This could be a useful tool for distinguishing between catchments for GIS studies, and long term planning for ecological management of catchment areas.  相似文献   

17.
为了阐明高寒草甸退化过程中植物群落物种多样性、生产力与土壤特性的关系, 在青藏高原东缘的玛曲县沿着高寒草甸退化梯度选取了轻度退化草甸、中度退化草甸、重度退化草甸和沙化草甸, 测定了高寒草甸退化过程中植物群落物种多样性、生产力与土壤理化性状. 结果表明: 从轻度退化到中度、重度和沙化草甸, 植被地下生物量分别降低了36%、48%和91%, 总生物量分别降低了34%、47%和91%, 土壤有机碳分别下降了18%、81%和97%, 全N分别下降了25%、82%和95%, 全P含量分别下降了14%、33%和41%. 随着高寒草甸的退化, 植被群落的生物多样性和地上生物量呈先稳定后降低的趋势, 土壤砂粒含量、pH值和全K含量呈增加趋势, 黏粉粒呈降低趋势, 速效N、速效P和速效K呈先增加后降低的趋势. 相关分析表明, 群落物种多样性和生产力与土壤有机碳、全N、全P、速效N、速效P、速效K、黏粒含量、粉粒含量、水分含量均呈显著正相关(P<0.01), 而与土壤砂粒、全K和pH值均呈显著负相关(P<0.05). 因此, 高寒草甸退化过程中, 土壤质地、养分和水分等的复杂变化及其相互关系共同决定着高寒草甸群落物种多样性和生产力的变化. 同时, 植被生产力和土壤碳、氮的降低产生明显的正反馈效应, 导致在重度退化阶段和沙化阶段, 植被生产力和土壤碳氮的急剧下降.  相似文献   

18.
Biological soil crusts (BSCs) perform essential ecosystem functions in arid and semi-arid ecosystems worldwide. The formation, development, and distribution of BSCs are influenced by changes in multiple environmental factors, including changes in the vascular plant community. The influence of changes in vegetation factors on BSC cover in 8-, 12-, and 16-year-old rehabilitated grasslands were studied in the hilly area of the Chinese Loess Plateau. The rate of degradation of BSCs underneath litter (P < 0.01) and the degradation cover of BSCs (P < 0.05) differed significantly between the 8- and 16-year-old successions. Stepwise multiple linear regression analysis showed that the main vegetation factors influencing the dynamics of BSC cover differed among the 8-, 12-, and 16-year-old rehabilitated grasslands. Basal cover, phytomass, and litter cover were the main vegetation factors influencing the dynamics of BSC cover on 8-year-old rehabilitated grassland. Phytomass, litter thickness, and litter cover were the main factors influencing the dynamics of BSC cover on 12-year-old rehabilitated grassland. On 16-year-old rehabilitated grassland, Pielou evenness index, litter thickness, and litter biomass were the main vegetation factors influencing degradation of BSC cover underneath litter, whereas basal cover, litter thickness, and litter biomass were the main vegetation factors influencing the degradation cover of BSCs. At particular stages of herbaceous succession, vegetation factors can have a large influence on changes in the community’s basal cover and litter, which are key factors influencing changes in BSC cover. The degradation of BSCs underneath litter may be a result of complicated eco-physiological processes.  相似文献   

19.
Due to deficient water resources in the Loess Plateau, watershed management plays a very important role, not only for ecological and environmental protection but also for the social development of the region. To better understand the hydrological and water resource variations in the typical watershed of the Loess Plateau and the Qinghe River Basin, the influences of land cover and climate change were analysed, and a SWAT model was built to simulate the response of the hydrological situation to land cover changes that have occurred over the past 30 years. The results demonstrated that the main land cover change occurring in the Qinghe River Basin was the conversion of land cover from grassland to woodland and farmland from the late 1980s to 2010. Woodland and farmland took 87.36 and 10.55%, respectively, from the overall area transferred over 20 years and more than 18% of the total watershed area. Hydrological simulation results indicated that land cover played a predominant role in the hydrological variation of the Qinghe River Basin, although the effects of climate change should not be discounted. The significant changes in land cover could be superimposed by policy orientation and economic requirements. Although it is hard to evaluate the land cover changes and the corresponding hydrological responses in a simple language, related analyses have demonstrated an increasing trend of runoff in the dry season, while there is a somewhat decreasing trend during the flood season in the river basin. There results could be significant and provide a positive influence on both future flood control and the conservation of water and soil.  相似文献   

20.
肖婧  王兵 《水科学进展》2020,31(6):820-831
为研究黄土丘陵沟壑区多种因素对撂荒草地入渗特征的影响,采用野外自然降雨观测法,研究不同降雨特征（降雨量、平均雨强、降雨历时和最大30 min雨强（I30））、土壤前期含水量、坡长（10 m、20 m、30 m、40 m和50 m）和植被盖度条件下土壤入渗特征差异,通过灰色关联度法判断影响撂荒草地入渗特征的主导因子。结果表明:①入渗量随降雨量、降雨历时和I30增加而增大（R2>0.55,P < 0.01）;入渗补给系数随降雨量、I30和平均雨强增大而减小（R2>0.12,P < 0.05）;平均入渗率随降雨强度、I30增加而递增（R2>0.53,P < 0.01）。②入渗量和平均入渗率随前期含水量增加而减少,入渗补给系数随之增加而增大（R2>0.13,P < 0.05）。③入渗量、入渗补给系数和平均入渗率总体随坡长增加而增大（R2>0.56,P < 0.01）,但在坡长30 m和40 m之间存在临界坡长。④在入渗效率较高的情况下,植被对土壤入渗的影响并不显著,降雨特征和坡长成为主导因子。  相似文献   

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