[Background] Changting County is one of the most serious counties in the area of granite red soil region in the south of our country, where is also very typical and representative because its soil and water loss has the characteristics of long history, wide area, large degree, and great damage. [Methods] In order to dynamically monitor the spatio-temporal changes of recent years'soil erosion in Changting County that is the demonstration area of soil and water loss management and ecological civilization construction, we used the USLE model to quantitatively estimate the changing situations of this county's soil and water loss in recent 25 years, according to the remote sensing data of 9 periods'Landsat series from 1988 to 2013, and using the topography, soil and meteorological hydrological literatures and with the field trips. [Results]The results showed that,the situation of Changting County's vegetation coverage was fine generally. The areas of higher vegetation coverage were mainly distributed around the county, and the central areas along two sides of Tingjiang River had lower vegetation coverage due to the serious situation of soil and water loss. The vegetation coverage showed a downward trend generally from 1988 to 1994, and became the worst in 1994. During the periods of 1994 to 2003, the situations of vegetation coverage in the most area of this county were improved obviously, especially that of the villages and towns in the middle areas. After 2003, the vegetation coverage changed little in the western areas, but in Cewu, Hetian, Sanzhou, and Zhuotian and some other towns, it increased greatly. The situations of the soil and water loss in Changting's most areas were mild, and the serious areas mainly distributed in Changting's middle area and southern towns. Especially, Hetian Town, Zhuotian Town, Sanzhou Township and Cewu Township were the most serious areas suffering from soil erosion. The results of remote sensing dynamic monitoring during 1988 to 2013 showed that the whole situation of the soil and water loss was improved significantly. It became worse and worse from 1988 to1994, and was at the worst in 1994. Later the situation was improved year by year after 1994, and especially after 2003, the both situations of the vegetation cover and middle area's soil and water loss in Changting got better. [Conclusions] The analysis mentioned above proves that using the USLE model to estimate the soil erosion modulus of Changting County may have high accurate and reliable results, which really reflects the temporal and spatial changes of this county's soil erosion over the last 25 years. The results show the changing situations and the treatment effect of the soil and water loss in Changting County, as well as provide a scientific basis to understand its current present situations and orient the corresponding treatment directions.

[Background] Large areas of degraded lands have been restored in red soil regions of south China since 1980s, which provides tremendous ecological and economic services such as soil and water conservation, carbon sequestration and environment protection. Some problems such as soil degradation,soil and water loss and tree disease decline, however, also appeared after several decades of ecological restoration due to lack of knowledge about soil characteristics, which seriously threatens the stability and sustainability of plantation. The contents of carbon, nitrogen, and phosphorous are important indexes of forest management, which respond positively to the environmental conditions. In recent years, the ecological stoichiometry has received considerable attentions. However, few studies have been reported about the patterns of soil stoichiometry across ecological restoration. [ Methods ] We took Pinus. massoniana woodlands as research objects, and determined the content variations of total organic carbon (C), total nitrogen (N), and total phosphorous (P) in soil, as well as ecological stoichiometric ratios across different ecological restoration years at 6 sites. Six P. massoniana woodlands were the ones restored by 0 year (CK1), 2 years, 13 years, 30 years, 33 years, and secondary forest (CK2), respectively. Those study sites were expected to be distinguished at the level of ecological restoration years along the typical eroded red soil region in Hetian town, Changting County, Fujian Province. [Results] 1) The contents of C and N in soil increased in the restoring process of degraded red soil. However, the P content was not considerable changed. The soil C, N and P contents in the forest of restored 2-33 years were still significantly lower than those in CK2. 2) The ratios of C:N, C:P and N:P tended to increase with the restored years increasing, especially soil C:N ratio of restored 2-33 years was approaching to those in CK2. 3) C content and C:N, C content and C:P, N and N:P all were in positive correlation, but P content had no significant correlation with N:P. [Conclusions] Soil C, N and P contents were out of balance in the non-restored eroded red soil (CK1). Despite some areas have been restored for 30 or 33 years, the nutrient contents still were lower than those in secondary forest (CK2). In other words, the typical eroded red soil restoration is a long-term process. Moreover, soil stoichiometry ratios were mainly restricted by soil C and N contents in the restoring process of degraded red soil. It suggests that a vegetation recovery is more sensitive to N than to P at this typical eroded red soil region. Thus, this study will help to reveal the nutrient cycling of P. massoniana woodlands by combing with stoichiometric characteristics of soil C, N, and P comprehensively and systematically. Therefore, it is very important to guide the ecological restoration of eroded red soil,and further improving the productivity of forest system should be carried out.

[Background] Vegetation coverage is the main body of terrestrial ecosystem. Detecting the spatial distribution pattern of vegetation and its correlation with land-use will benefit the regional ecological environment protection and soil erosion control. [Methods] In this study, taking the Dan River Watershed, the water source of the middle route of the South to North Water Diversion Project, as the research area, MODIS 250-m NDVI data and GIS technology were used to obtain spatial distribution features of the different NDVI degree in the case of elevation, slope-degree and slope-direction via overlap of distribution maps of NDVI and topographic factors maps extracted from digital elevation model. Finally, the correlation between NDVI and land-use types was analyzed. [Results] The results showed that: 1) The average NDVI value was 0.85, which indicated that the ecological environment was fine in Dan River Watershed. The high vegetation coverage distributed in marginal areas of watershed, and relatively concentrated in northeast and southeast; while the middle vegetation coverage distributed in low mountain, and relatively concentrated in northwest and south. Low vegetation coverage distributed in the Dan River valley as point and linear way, especially in city area. 2) At the different elevation and slope- degree, the distribution of area percent of high and middle vegetation coverage was assumed as single peak. The vegetation coverage area percent was proximal zero in the flat. The vegetation coverage area in the case of different slope-directions was not different dramatically. 3) Except different slope-direction, at different elevation and slope-degree, the high and middle vegetation coverages were significantly correlated with farmland, forestland and grassland. Moreover, low vegetation coverage was significantly in correlation with construction land and waters in the different topographic factors. [Conclusions] Some conclusions have been obtained that the degree of vegetation coverage showed obvious revese distribution characteristics with human activities range in Dan River Watershed, which indicated that human activities had a great impact on vegetation distribution Optimization of land use structure and appropriate increase of area were beneficial to improve the soil and water conservation function of Dan River Watershed.

[Background] Due to the deterioration of ecological environment, forest service functions were getting more and more attention. Forest function is closely influenced by the structure. It has been the research focus that how to quantitative describe the relationship between forest structure and function. The purpose of this study is to define the quantitative relationship between Cunninghamia lanceolata forest stand structure and function through the multiple regression model, and then to improve the forest multi-function management level and forest benefits by adjusting forest structure. [Methods] C. anceolata and its mixed-forest which is typical in Jiangle state-owned forest farm in Fujian Province were taken as an example. Seventeen easy measuring factors (stand age (A), stand average diameter at breast height (DBH), stand average height (H), stand density, maximum water holding capacity of litter, soil non-capillary water capacity, total P, total K, total N, organic matter content, tree layer biomass, shrub layer biomass, herb layer biomass, shrub richness, herb richness, shrub diversity, herb diversity) were chosen as independent variables ( IV), functions including forest biomass accumulation, water conservation, soil conservation and species diversity conservation were considered as dependent variables, then a forest structure and function model was built by multiple linear regression method, and a forest comprehensive function model was finally established by principal components analysis method. [Results] The stand biomass per hectare was mainly determined by A, DBH and stand density (R2 = 0.801 4). Water conservation function was mostly influenced by A, DBH, H and stand density (R2 = 0.5612). Soil conservation function was mainly affected by A, DBH and H (R2 =0.561 2). Richness and diversity of undergrowth were determined by A, DBH, H and stand density (R2 =0.661 8). Factors including A, DBH and stand density had influences on all of the studied forest functions, while stand average height had a significant effect on forest water conservation function. In the forest comprehensive function model, first five principal components, respectively, reflected the forest timber production function, species diversity conservation function, soil onservation function, biomass accumulation function and water conservation function. Among the 55 sample plots, the highest forest comprehensive function index (FI) was 453 (No. 19) while the lowest was -153 (No. 5). Sample plot No. 19 had a significantly higher index in A, DNH, H and tree layer biomass than No. 5. [Conclusions] Forest multi-function was mainly determined by stand age and average DBH. 82% of Chinese fir forest had a powerful forest comprehensive function, however, 18% of Chinese fir forest had a weak timber production capacity and diversity protection ability, which needs forest stand structural adjustment to raise its forest multi-function level.

[Background] Hydrological data in Li River showed that the distribution of its water resource was not uniformity. During the flood season a large amount of sediment along with the runoff flowed into the river due to the vegetation degradation, which caused the deposition of the river and the increasing of the river bed. The rainfall and surface runoff is one of the main causes of soil and water loss, and the accompanied environmental problems from soil erosion such as riverbed elevation and water quality deterioration should be solved urgently. Usually the external natural factors cannot be controlled, but the controllable factors such as the improvement of the surface cover and the soil condition can effectively alleviate the soil erosion on the slope. [Methods] In this study, 7 experimental plots were established according to the different vegetation configuration. Plots were built in vegetation strips of Li River in Guilin, Guangxi Autonomous Region, where the slope was 5°. We set the rain collecting pool in the area of plots爷outlet, which aimed to collected surface runoff flows through the plots. During the flood season we observed the runoff and sediment loss under the condition of natural rainfall, the runoff was measured through the volume method, and the sediment content was measured by the water quality analyzer in this experiment. The data were processed by Excel 2007 and analyzed by SPSS18.0 software for correlation analysis. [Results] 1)Vegetation significantly intercepted runoff and sediment, the higher the vegetation coverage was, the better the interception was; thus the vegetation coverage should be increased in the restoration areas, which could effectively prevent and control soil erosion. 2) The riparian vegetation covered by Setaria plicata intercepted runoff and sediment better than others, S. plicata should be preferably selected as the shore plants in bare degradation area of Li River. 3) Pure herbaceous vegetation intercepted sediment better than that of grass and shrub vegetation. However different vegetation arrangements had their respective advantages and disadvantages, during vegetation restoration we should choose different vegetation configuration modes according to the needs. 4) Surface runoff and sediment were positively correlated with rainfall and rainfall intensity at the level of P <0.01, there was a close linear relationship between runoff and sediment. [Conclusions] Thus, through some ways such as increasing vegetation cover on bare slope surface, selecting S. plicata as the fast green grass in Li River, establishing the interception measures on the top of slope, and so on, the soil and water loss could be effectively reduced, the non-point source pollution caused by soil erosion could be alleviated.

[Background] Quantitative analysis on the effects of climate variability and human activities on runoff is one of the keys to inquiring about runoff change mechanism and control of soil erosion. Minjiang River is the largest river in Fujian Province,and the change of water resources has important influence on social economy and ecological environment. In recent years, many researches focused on the change characteristics of runoff, precipitation and temperature in Minjiang River Basin. However, little studies have reported on the change characteristics of potential evaporation, and the relative effects of climate variability and human activities on runoff. [Methods] The observed monthly river discharge of 4 hydrological stations and monthly meteorological data (precipitation, temperature, wind, sunshine hours, and relative humidity) of 23 meteorological stations for the period 1960 2010 were collected. Characteristics of the variation of hydro-climatic changes over the last 51 years were analyzed based on the TFPW-MK, and the relative effects of climate variability and human activities on runoff were investigated based on an empirical discriminant method and climate elasticity method. [Results] Firstly, runoff and precipitation of the Minjiang River were on the rise in general while potential evaporation was declining and had a sudden change in the early 1970s. Secondly, relative effect of climate variability was greater than that of human activities in Minjiang River Basin and three sub-basins under different decades relative to 1960s, except in the beginning of 21st century in Jianxi River sub-basin and Shaxi River sub-basin, in which the contributions of human activities accounted for 60% and 52% of the changes in streamflow, respectively. Additionally, the contribution of the climate variability on the runoff in Minjiang River Basin and Futunxi River sub-basin was the largest in the 21st Century, accounting for 86% and 89% of runoff changes respectively, and the contribution of the climate variability in Jianxi River sub-basin and Shaxi River sub-basin was the largest in 1990s, accounting for 86% and 89%, respectively. [Conclusions] In general, the results from the empirical discriminant method and climate elasticity method were the same on the whole, climate variability leaded to an increased streamflow while human activities always resulted in a decrease of streamflow. The increase of precipitation and decrease of potential evaporation were the major reasons for the increase of runoff. Moreover, the relative effects of climate variability and human activities varied among sub-basins, and the differences in the internal climate and human activities were the main reasons. The impact of climate variability on runoff was the most significant in the Minjiang main stream and three sub-basins in 1990s; the impact of human activities on runoff was the most significant in the Minjiang main stream and Futunxi River sub-basin in 1990s and in Jianxi River sub- basin and Shaxi River sub-basin in 1980s and the beginning of the 21st century, respectively.

[Background] Dry-hot valley is one of ecologically fragile areas and it is also a difficult strip for vegetation recovery. Forest vegetation plays an important role in reducing water loss and soil erosion, sand prevention, and improving the deteriorating ecological environment. [Methods] We combined the method of the field investigation and indoor analysis to measure the main physical and chemical properties of six types of different woodlands (Pinus armandii + Coriaria nepalensis + Lolium prenne, P. armandii + Larix gmelinii, Juglans regia, P. armandii, Zanthoxylum bungeanum, and Morus alba) and farmland in the dry-hot valley of Qiaojia County. The study also used a method of the subordinate function evaluation to evaluate the effects of the soil improvement for six kinds of forests, which aimed to provide scientific basis and practical reference for the selection of ideal forest types for the project of returning farmland to forest. [Results] The results showed: 1) Soil structure of different woodlands was improved to some degree and soil nutrients were further improved, and moisture content, total porosity, capillary porosity, organic matter, total N, total K and available K decreased with the increase of soil depth between different woodlands,while the soil density showed an opposite trend. In addition, soil density, moisture, organic matter, soil total nutrient and available nutrient all showed an order of mixed forest of trees, shrubs and grasses > mixed trees forest > pure forest. 2) The evaluation on effects of the soil improvement of six kinds of typical forests showed: Pinus armandii + C. nepalensi + L. prenne > P. armandii + L. gmelinii > P. armandii > farmland > M. alba > J. regia > Zanthoxylum bungeanum. [Conclusions] On the whole, the effects of soil improvement were obvious since the project of returning farmland to forest. P. armandii + C. nepalensis + L. prenne had the best effects of soil improvement while P. armandii + Larix gmelinii ranked the second. Among the pure forests, P. armandii had the highest effect of soil improvement, J. regia and M. alba were roughly the same, and Z. bungeanum was the lowest. P. armandii + C. nepalensis + L. prenne (mixed forest of trees, shrubs and grasses) was an ideal model for soil improvement in the local area, which was suitable for promotion in the dry-hot valley area. We suggest that evaluation of the effects of soil improvement should be carried out from time to time so as to increase the soil uptake of N and P to improve the local ecological environment.

[Background] The characteristic of the plant community structure and the plant diversity in the course of natural restoration of vegetation is a scientific basis to construct artificial vegetation in semi- arid loess area of northern Shaanxi, which is the typical fragile ecological region. [Methods] The paper explored what was the influence mechanism of the topography on natural vegetation in this region, for Hegou watershed in Wuqi County of Shaanxi Province as an example. Based on the vegetation survey in 50 sampling plots, the community structure and the plant diversity were nalyzed from three aspects of landform , slope and gradient. [Results] The results showed that the plant community was still mainly herbaceous and the zonal vegetation type was Artemisia sacrorum + Stipa bungeana communities in this watershed, which had been fenced for 15 years. Not only were there Populus simonii and Salix matsudana on gully bottom, but there were also three trees of P. simonii, Ulmus pumila and Ameniaca sibirica and six shrubs of Buddleja alternifolia, Prinsepia utilis, Spiraea trilobata, Caragana korshinskii, Caragana microphylla and Periploca sepium on some micro-topographies of slope aspect with favorable water condition, i. e. , gully, collapse and platform. On different landforms, the order of the richness index was valley slope > gully slope > top valley > gully bottom; that of the diversity index was valley slope > top valley > gully slope > gully bottom; and that of the evenness index diminished from top to bottom. On different slopes, both the diversity and evenness indices were in the same order of size, i. e. , shady slope > semi-sunny slope > semi-shady slope > sunny slope, but the richness index was in the order of semi-shady slope > semi-sunny slope > shady slope > sunny slope. Moreover, with the increase of gradient, the richness index decreased gradually, and the evenness and diversity indices were both of “ S冶types, and its maximum value was at 32 of gradient. [ Conclusions] Therefore, in summary, in the process of artificial vegetation of restoration and reconstruction in this region, we should figure reasonable vegetation layout according to the differences of the restoration ability of natural vegetation on different terrains. In order to enrich the structure and optimize the ecological function of the plant community, the appropriate proportion of trees or shrubs could be configured on gully bottom and some micro-topographies of slope aspect, in where water condition meets the need of trees and shrubs. But on sunny slope, especially the steep slope, it should be the first task to protect and restore the herbaceous community. In addition, to speed up the process of vegetation restoration in the loess area of northern Shaanxi, some positive trees or shrubs should be properly distributed based on artificial measures, such as fish scale pit of collecting water or level bench of reducing gradient.

[Background] Mountains in Beijing are in an ecologically fragile area with seasonal drought; therefore, study of water source of typical tree species before and after the rain in arid areas is of great significance. [Methods] By taking Pinus tabulaeformis and Platycladus orientalis in mountains in Beijing as subject, we employed the hydrogen and oxygen isotope technique and measured the isotopic composition in branches of trees, soil, groundwater and rainfall in order to clarify their water source before and after the rain. [Results] The results showed that the soil moisture content and the isotope of the two species showed a vertical change. P. tabuliformis and P. orientalis forest soil were different in soil moisture content before rainfall. Soil moisture content in Platycladus orientalis layers was lower than that in Pinus tabulaeformis. The average soil moisture content was 7.44% and 2.17%, respectively. After the rainfall, soil moisture content in the stands of two typical species were higher than before, the average soil moisture content in the P. orientalis stand increased by 46.1% compared to that before rainfall, while it increased by 38.7% for P. tabuliformis. The intense evaporation of surface soil water caused the isotope fractionation and enrichment heavy isotopes. Decreasing with soil depth, soil water D in P. tabuliformis and P. orientalis stands showed a tendency to increase, and the heavy isotope was enriched. Different plant species had different water sources in the same season, and the same plant species had different water sources before and after the rain, showing an adaptation to their habitats. P. tabuliformis had fewer roots in urface soil, but still absorbed a high amount of topsoil water before rainfall, with a utilization rate of 36.0%; in order to obtain a stable water supply, P. tabuliformis used the developed deep roots to absorb underground water with a utilization rate of 38% and 58.2%, before and after rain, respectively. P. orientalis used deep soil water to maintain normal physiological activities, and the utilization rate was 71.2%. The lateral root in the surface layer soil of 0 -20 cm was sensitive to rainfall, and P. orientalis mainly used surface soil moisture with a utilization rate of 71.6%. [Conclusions] Our results have great significance for artificial afforestation, tree species configuration and alleviation of the water resource shortage in arid and semi-arid areas.