[ Background] Black soil region is one of important grain production bases in China.However, the decrease of crop production has been obvious due to soil erosion by long-term cultivation.Previous researches focused on impacts of erosion on aboveground biomass and yields by using pot, pool or plot experimental methods, and paid little attentions to impacts on root growths. This study is to clarify the response of aboveground biomass, yields, root growths and their relationships to eroded black soils.[Methods] Both moderately and severely eroded black soil fields in Heshan farm of Heilongjiang Province were selected for the study, and the aboveground biomass dry weight (BDW ), leaf area index (LAI), and root growths every 10 days during different growth stages for maize and soybean in 2014 and 2015 were measured, and yields were obtained during the harvest time. A root sampling method of 5 holes for each soil layer with 15 cm depth by using a soil auger was proposed, and the root biomass and length were measured after washing root samples. [Results] The soil erosion significantly reduced the yield of maize and soybean. Compared with moderately eroded soil, severe erosion caused the reduction of yield by 32.7% for maize, and 57.1% for soybean. Soil erosion caused more obvious effects on the aboveground biomass, especially during the reproductive period, comparing with impacts on root growth. Severe erosion caused the decrease of BDW by 20.5% and 51.4% for maize during the middle and later growth respectively, and 21.9% and 55.7% for soybean, relative to moderately eroded soil. The growing rate of BDW also was more sensitive to soil erosion than that of RMD. From view of the impacts of erosion on the relationship between aboveground and underground biomass, the root shoot ratio increased with more severe erosion. The root shoot ratios of maize increased by 42.4%, 25.8%, 57.1% during the early,middle and later growth stages relative to the moderate soil erosion condition, and creased by 62%,54.2%, 85% during the early, middle and later growth stages for soybean. The percentage of root biomass to total root depth for two crops declined exponentially with soil depth. The percentage of root dry weights within the 0 ~15 cm deep soil layer to total root depths were more than 90% and 85% for maize and soybean respectively. Of two eroded soils, the percentage of root biomass of the surface layer to the total root depth was higher in moderately eroded soil than that in severely eroded soil. [Conclusions] This study indicated that crops adapted to harsh soil environment by developing their roots for absorbing more nutrients and moisture. This study also provided a method for sampling root, and explained the impact mechanism of eroded black soil on crop yields from the view of root growth and its relations to aboveground biomass. The results provide a reference for crop study in this region and lay a foundation for crop model research to modify the crop growth in the nature.

[ Background ] Riparian soil and vegetation along rivers are important for biodiversity maintenance and biogeochemistry circulation of river ecosystems, and are the basis of many ecosystem services. Influenced by human activities and natural factors, soil structure and vegetation in the riparian buffer zone of the middle and lower reaches of the Yellow River are subjected to degradation to a certain extent. [Methods] Selecting the Zhengzhou-Kaifeng section of the middle and lower reaches of the Yellow River as the studied area, as well as using methods of field investigation, experimental analysis,and canonical correspondence analysis (CCA), the present study was conducted to investigate the fractal dimension characteristics of riparian plantation soil particle size at the surface layer of 0 - 20 cm under different vegetation types and buffer distances. [Results] The results indicated that the soil particle size distribution (PSD) was heterogeneous with higher contents of silt and clay (more than 75.5%) and less content of sand. However, soil texture was uniform in spatial, since no significant difference was observed between Salix matsudana plantation and Populus tomentasa plantation as well as among the four riparian buffer zones ( < 1.5 km, sample number (n) = 13; 1.5 -3 km, n = 11; 3 -4.5 km, n = 11; > 4.5 km, n = 12). The fractal dimension ( D) value was approximately equal to 2.75, suggesting a fine soil structure with favorable performance in the retention of water and fertility in the studied area. Result from Pearson correlation analysis indicated that D value and clay content were significantly and positively correlated with soil total carbon (TC), total organic carbon (TOC), and total nitrogen (TN) at the 0.01 level, on the contrary, sand content was significantly and negatively correlated with TC, TOC, and TN at the 0.01 level, while silt content was only significantly and positively correlated with TN at the 0.05 level. Result from CCA indicated that the community characteristics such as the herb height, tree diameter of breast height, tree height, and tree cover were related positively and closely with D value, silt content, and clay content, while were negatively correlated with sand content, suggesting that the larger tree coverage and biomass can lead to the better soil structure. Moreover, inconsistent with other research results, the soil particle size distribution and fractal dimension characteristics were less affected by elevation because of the small gradient variation in the studied area. [Conclusions] The riparian buffer zone of the middle and lower reaches of the Yellow River, which is affected by both human activities and natural factors, is subjected to serious issues of soils such as loose structure, decreased organic matter content, and significant desertification, thus results from this study can provide basis for ecological restoration, bank erosion control, and land management of the degraded riparian zone.

[Background] Under the background of global change, vegetation dynamics and research on its relationship with climate is one of the focuses of the current international scientific problems. The study on the trend of vegetation coverage and response to climate is of great significance for global research, furthermore, it also benefits to global ecological processes and global ecological environment. [Methods] The annual and seasonal change trends of vegetation coverage were examined by employing MODIS-NDVI datasets in Xilin Gol League from 2001 to 2010, and then using Sen + Mann-Kendall model to analyze the significant level of the vegetation change further. In the end, based on the region of the meteorological data, mainly including the local temperature and precipitation, and using correlation analysis, the patterns of spatiotemporal variation of vegetation and its response to climate in Xilin Gol League during the period 2001—2015 was investigated. [Results] 1) The average vegetation NDVI showed a trend of greater volatility during 2001 to 2015 in the studied area, the change trend of process presented two waves, and the two higher values appeared in 2003 and 2012, of which 2008 vegetation NDVI appeared a temporary rise. Meanwhile, this highly correlated with the precipitation peak, it suggested that the increase of precipitation was a main reason of Xilin Gol League area vegetation to be improved. 2) The NDVI generally presented the distribution characteristics of “high in west and low in east冶, and this kind of distribution characteristics were consistent with the distribution of grassland type, from west to east in the order of desert grassland > typical steppe > meadow steppe. In terms of temporal characteristics, the overall trend was in rise, in detail, the trend was first rising after falling. The spatial distribution showed that NDVI increased significantly in southern and declined significantly in western. Significant increase in size for the grassland types was in the order of meadow steppe > typical steppe > desert grassland. 3) The peaks of NDVI were corresponding to the peaks of precipitation, but because of space differences in geographical location and climate conditions, the correlation between vegetation change and climate were different in each season and vegetation type, the vegetation variations were mostly influenced by precipitation in spring and summer, while it was controlled by temperature in autumn. [ Conclusions] The improvement of vegetation conditions in the studied area was closely associated with precipitation, although ecological measures like returning farming to forest benefited to the growing of vegetation, plenty of rainfall may guarantee the increase of vegetation coverage. Thus, only comprehending regional climate condition may play maximum function in ecological engineering.

[ Background ] It is especially significant to study the hydrological and meteorological elements of river basin against the backdrop of global warming. The river runoff is a result of combined influence from both meteorological factors and the condition of underlying surface. Climate change is one of the major driving factors in the variation of runoff and also exerts direct impact on the water resources system. Despite of that, the underlying surface transformation by human being activities also change the runoff of river basin. [Methods] In order to reveal the influence of eteorological factors and the disturbance of human activity on the runoff change in Yanhe River basin, this article analyzed the runoff and meteorological elements of Yanhe River basin from 1955 to 2012 by means of Mann Kendall test and R/ S methods. The year of abrupt runoff change was identified by Pettitt's test, and the hydrological sensitivity analysis was adopted to quantitatively differentiate the contributions between meteorological elements and human activities to runoff change of Yanhe River basin. [Results] The precipitation and runoff happened much more from June to September, during this period, the precipitation and runoff were 71% and 63% of the total annual amount. The runoff presented an increasing tendency in Jan. , Feb. ,May, Dec. , especially in Jan. respectively; and the runoff in other months descended, especially in March, July, Aug. respectively. The runoff showed a descending tendency in spring flood period from March to April and flood period from June to October. Conversely, the runoff in drought period increased. It showed that the annual runoff distribution tended to be more even, and the runoff process became mild. During the 58 years between 1955 to 2012, the precipitation of Yanhe River basin reduced 89.4 mm, with a temperature rising of 2.15 ℃and a 17.3 mm decrease of runoff depth, both climate and runoff depth registered evident variation,  monstrating a warming-drying trend of the basin. As the Hurst index indicated, this trend will remain in a period of time in the future. According to the Pettitt change-point test, the abrupt change of runoff occurred in 1996. The average annual runoff depth dropped 11.7 mm during 1996- 2012 compared with that of 1955, among which the contribution rate of human activities was 56% while climate change contributed 44%. [Conclusions] This article illustrates that the climate of the Yanhe River basin had the tendency of warming and drying, and human activities accounted for a large proportion in the runoff reduction. The results of the study in this area have favorable guiding significance to the reasonable use of water resources and the management.

[Background] Early development stages of trees are expected to be more sensitive to climate change, and represent a major bottleneck to plant community recruitment. In North China, drought index had increased dramatically since 1990s, understanding on seedling's response to anticipated decrease in water availability is urgently needed. Larix principis-rupprechtii and Pinus tabulaeformis are two dominant coniferous tree species in North China, and play significant ecological roles in water conservation.[Methods] We collected seeds of these two species from Guandi Mountain, Shanxi Province, and conducted a controlled greenhouse experiment to investigate how climate changes ( warming and precipitation change) would affect their seedling emergence and growth. Three levels were set for both temperature and water supply. Temperature levels were monthly mean temperature (T ₀) over the past 15 years (1999- 2013), increased by 2 ℃(T₁) and by 6 ℃(T₂). Water supply levels were monthly mean precipitation (W) over past the 15 years (1999- 2013), reduction by 20% (W - ) and addition by 20% (W + ). A two-way ANOVA was used to compare seedling growth ( including seedling emergence percentage, needle length, height, length of main root, number of lateral root, and length of lateral root) between the two treatments to the species. If the interaction was tested to be significant (P <0.05), one- way ANOVA was used to test the effects of water treatments on seedling indexes, and multiple comparison was used otherwise. The least significant difference method (LSD) was used to test the significant differences of all data at level of 0.05. [Results] Seed germination of the two species was affected by temperature and precipitation changes. Seedling's stable germination time reduced and seedling emergence percentage improved by increased temperature of 2 ℃ and water addition. However, in the condition of increased temperature of 6 ℃ or water reduction, stable germination time of seedling delayed and seedling emergence percentage decreased. Seedlings of the two species presented different responses to the climate change. L. principis-rupprechtii was affected more greatly by warming and drying climate than P. tabulaeformis. Seedling morality of L. principis-rupprechtii increased sharply and seedling height decreased by higher temperature and water reduction. The changes from increased temperature or precipitation showed no significant effects on seedling survival and aboveground-growth of P.tabulaeformis. Underground growth of both L. principis-rupprechtii and P. tabulaeformis increased by longer primary and lateral roots. [Conclusions] Soil drought was induced by dramatically increased temperature and reduced precipitation, which resulted in adaptive strategy of the two species by reducing aboveground growth and giving priority to root growth. Seedlings showed an interspecific variation of response to water deficit. L. principis-rupprechtii was more sensitive to climate change than P.tabulaeformis. The regeneration of L. principis-rupprechtii was inhibited by warming and drying climate. The seedling growth was negatively affected by highly increased temperature in growing period, and it could not be improved by water addition.

[Background] Surface runoff of cold and arid regions is particularly sensitive to climate change, climate factors such as precipitation, potential evaporation, temperature of the slight change, can cause the change of surface runoff system. At present, the impacts of climate change on runoff,mainly were focused on single statistical analysis on the impact of meteorological factors on runoff, and ignoring the mutual influences among the impact factors. In fact, the complicated relationship between meteorological factors is multivariate. [Methods] Taking Xilin River basin as research target, the relationship between runoff and varied factors of precipitation, average temperature, highest temperature,lowest temperature, sunshine duration, potential evaporation and effective accumulated temperature were studied on yearly time-scale and seasonally time-scale by the method of correlation, partial correlation and path analysis, and their direct and indirect impacts on the runoff were determined by path analysis. The data were obtained from 4 national weather stations in 1960—2010, one weather station is Xilinhot station in the area, and other three are Abaga, Linxi and Keshiketeng stations near the area. The runoff data were from Xilinhot hydrometric station measured in 1960—2010. [Results] There were two obvious flood seasons of runoff process in Xilin River, they were April spring flood and the summer flood in July. The correlations between runoff and factors of sunshine duration, annual average temperature, minimum temperature and maximum temperature in yearly time-scale were insignificant. Both the direct effects and the indirect effects through other factors on the runoff were also little, thus they were not the main meteorological driving factors affecting the runoff. The correlation between runoff and precipitation, potential evaporation, effective accumulated temperature was highly significant, and the direct effects of them on runoff was high, therefore they were the main factors affecting on the runoff in yearly time-scale.On the seasonally time-scale, the top 3 factors impacting runoff were also potential evaporation, rainfall and effective accumulated temperature. Different weather factors contributed differently to the runoff of Xilin River in different seasons; the main control factor was effective accumulated temperature in spring,while in summer and autumn the main atmosphere control factor was precipitation. Due to the influence of seasonal frozen soil, the correlation coefficient and direct path coefficient between runoff and accumulated temperature was significantly higher than the those between runoff and temperature, especially in the spring, the direct path coefficient between runoff and accumulated temperature even was higher than that between runoff and precipitation. [Conclusions] The direct correlation between runoff and atmospheric variables can be determined by path analysis in the study of relative importance of each climatic factor, thereby determining the impacts of those factors on runoff change and providing a reliable basis for decision-making.

[Background] Cinnamomum camphora is a precious economic tree species, it has important application value in the southern coastal areas of soil and water conservation. There are varied degrees of salinity in the southern coastal regions, the research on C. camphora 's salt tolerance had been little reported, nor systematically. The purpose of this work is to study the salt tolerance of C. camphora, and to provide the reference for the cultivation in saline alkali soil in southern coastal regions. [Methods]We chose C. camphora seedlings as test materials and used potted method, the seedlings were treated with NaCl treatment at 2‰, 4‰, 6‰and 8‰, and fresh water as the control (CK). With different NaCl salt treatment, the C. camphora growth indexes, moisture physiological indexes, photosynthetic pigment content, antioxidant enzymes activity, osmotic regulation substances and membrane stability of leaves were measured; the photosynthesis parameters and chlorophyll fluorescence parameters were measured by CIRAS-2 and CFI, respectively. [Results] 1) With the increasing of salt concentration, C. camphora seedling height and relative growth rate of base diameter decreased, and more than 4‰ of the salt treatment had significant inhibitory effect on the growth(P < 0.05). 2) With the increasing of salt treatment concentration, the water saturation deficit (WSD) and malondiadehyde (MDA) content of seedling leaf rose gradually, while the membrane stability index (MSI) and photosynthetic capacity decreased gradually. 3) The leaf relative water content (RWC), the photosynthetic pigment content, Fv/ Fm, NPQ, antioxidant enzyme activity, proline (Pro) content, and soluble protein (SP) content of seedling leaves at the salt concentration of 2‰ were higher than CK, while the MSI, Yield, and ETR reduced in a little magnitude. 4 ) The photosynthetic pigment content, net photosynthetic rate, photochemical efficiency, WUE, and MSI reduced significantly when the salt concentration was 4‰ (P< 0.05), while MDA content, and Pro content increased significantly ( P < 0.05), moisture conditions became worse; at the same time, the antioxidant enzyme activity, soluble sugar (SS) content,and SP content decreased. [Conclusions] The salt tolerance of camphor seedlings is 2‰ to 4‰, and when the salt concentration over 4‰, the growth of seedlings could be inhibited significantly. C.camphora seedlings could endure low salt stress (2‰) via increasing RWC, photosynthetic pigment content, the dissipation of NPQ, the activity of antioxidant enzymes, the content of Pro and SP, and shutting down part of the stomas. But when the salt concentration reached 4‰, with the increase of salt concentration, the antioxidant enzyme activity of seedling leaves gradually declined, the damage of enzyme system was more and more serious; the regulating effect of SS and SP became smaller; Pro was producing massively, and the regulating effect of osmotic regulation increased gradually, but far enough to resist the salt stress. Thus, the water in leaves lost severely, membrane lipid peroxided, membrane stability deteriorated, photosynthetic agencies seriously damaged, which resulted in their lives in danger.

[Background] Soil erosion is most serious in China, soil and water conservation plays an important role in the protection and using of land and water resources. Preventing soil erosion,maintaining healthy ecosystem are key parts of the construction of ecological civilization and ecological security of land. With the growing importance of the construction of ecological civilization, and the implementation of national and local major function-oriented zoning planning, preserving and enhancing functions of soil and water conservation has become one of the working direction of soil and water conservation in the new era, the study on function of soil and water conservation is also more and more. Combined with the national planning of soil and water conservation, function of soil and water conservation has profound significance. [Methods] From the concept, principles for determining types of soil and water conservation functions, evaluation index system and methods of soil and water conservation functions were set forth. The principles of determination include direct relevance, comprehensiveness and single function. Ten basic functions of soil and water conservation were determined as water resource conservation, soil conservation, water storage and conservation, sand fixation, ecological maintenance, disaster prevention and reduction, farmland protection, water quality maintenance, sand barring and reduction, living environment maintenance, and the qualitative and quantitative indicators of each function were assessed and graded. As an example with the eastern hilly region of Taihang mountain, process and the results of the water and soil conservation function evaluation were illustrated. [Results]Through case studies and statistical analysis, evaluation methods and the important role of the water and soil conservation function is clear, and distribution of functions and main direction of soil and water conservation work are proposed for eight first-grade regions. According to the area distribution of basic functions of soil and water conservation in third-grade regions, soil conservation and ecological maintenance as the basic function of third-grade regions have the largest area, the results show that the main work of soil and water conservation in China is still based on land resources protection and ecosystem maintenance. Respectively, from eight first-grade regions to see, the main functions of black soil region in Northwest China are soil conservation, ecological maintenance and water resource conservation, the main functions of north sandy region are farmland protection, sand fixation, ecological maintenance, the main functions of soil-rock mountain region in North China are soil conservation, water resource conservation, farmland protection, the main functions of the Loess Plateau region in Northwest China are soil conservation, water storage and conservation, sand barring and reduction, the main functions of south red soil region are soil conservation, living environment maintenance, water resource conservation, the main functions of purple soil region in Southwest China are soil conservation, ecological maintenance, water resource conservation, the main functions of karst region in Southwest China are soil conservation, water storage and conservation, ecological maintenance, the main functions of Tibetan Plateau region are ecological maintenance, water resource conservation. [Conclusions] Proposing water and soil conservation function, especially basic function is one of the innovations of the soil and water conservation planning, which inevitably has some guidance to national and regional soil and water conservation.

[Background] Evaluation of Ecological Services Value (ESV) is fundamentally important for measuring the sustainable level of social and economic development. Land use change affects ecosystem service value, through the interaction between ecological processes and services. In order to quantify the effects of land use change on the ESV in rocky desertification region,two counties (Longlin and Xilin) with rocky desertification in Guangxi were taken as research area. [Methods] Land use change of the research area during 2004 2010 was analyzed, based on remote sensing data validated with field investigation. The Costanza's calculation method was employed to quantitatively evaluate 9 types of ecological service values (i. e. , gas regulation, climate regulation, water conservation, soil formation and protection, waste treatment, biodiversity conservation, food production, raw materials, and aesthetic landscape). On the basis of the Xie Gaodi's equivalent weight factor of ESV, as well as combining with the local economic value of grain yield and costs of farmland, the coefficients of ESV of different land use type (per unit area) in the research area were estimated. [Results] Results showed that the areas of forest land, grassland, and construction land increased in both Longlin and Xilin, while arable land, water area, and unused land declined during 2004 2010. The coefficients of ESV in Xilin were higher than those of Longlin. The total ESV of Longlin and Xilin increased by 6.14 *108 and 3.27 *108 Yuan,respectively. The ESV of waste treatment and food production reduced, while the other 7 ESVs increased. The ESV of forest land was the dominant component. In order to verify the reliability of coefficients of ESV, the coefficients of ESV adjusted up or down 50%, respectively, the sensitivity coefficients of each land use type was less than 1. Sensitivity analyses indicated that ESVs were relatively stable in the research area and the results were credible. Analyses of eco-economic harmony degree indicated that eco-economic system was moderate in Longlin, and in the potential crisis in Xilin,respectively. [Conclusions] This study revealed that the total ESV increased was mainly due to the improvement of forest cover. The ESV of forest land was the major ecosystem service value. Ecological value is much greater than productive value of the ecosystem. The ecological environment has been improved in Longlin, but the ecological and economic development was in a low level in Xilin.Therefore, the ecological environment should be maintained in Longlin, and strengthened in Xilin. The ESV can be used as a comprehensive indicator to weigh the sustainable development of ecological environment in the rocky desertification region,which may provide reference for formulating the policies on ecological environment.

[Background] The metabolism of carbon and nitrogen is critical to tobacco. Organic material is the main source of the nutrient, which directly affects the carbon (C) and nitrogen (N) cycle of tobacco. In this study, we try to find the optimal type of organic material for the C and N cycle of the tobacco and the relevant soil in middle of Henan Province. [Methods] The pot experiment was carried out in the farm of Henan Agricultural University in 2015. Four treatments were set as: 1) no organic material application (TCK ), 2) add maize straw (TS ), 3) add pig manure (TM ), 4) add biochar (TB). Except TCK treatment, the C/ N ratio in TS, TM, and TB treatment were regulated as 25/1. The tobacco leaves and the soil were sampled on the 30, 45, 60, 75 and 90 days after the tobacco transplanted. The major chemical and biological indices such as the content of organic carbon, varied forms of N, phosphors (P), kalium (K), the relative enzyme activities of carbon and nitrogen cycle were measured. [Results] Added biochar and pig manure significantly improved the agronomic traits of tobacco, while, the opposite effect on tobacco was appeared under maize straw treatment. The activities of key enzymes related to C and N metabolism in the tobacco leaves were significantly promoted under biochar treatment. The highest activities of nitrate reductase, amylase, and invertase were 33.3 µg/ (g·h), 14.42 mg/ (g·min), and 5.08 mg/ (g·h), respectively. Compared to the control (without organic material added), the contents of N, P, and K in tobacco leaf were significantly elevated under the treatment with organic material application. Meanwhile, under the treatments with organic material, the soil urease activity was significantly improved under pig manure treatment, and the maximum value was 1.78 mg/ kg; while the soil sucrase activity changed little among the treatment. The contents of soil organic carbon and soil nitrogen were remarkably increased. Especially, the content of total nitrogen and available nitrogen in pig manure treatment were significantly higher than that in other treatments. The organic material promoted the soil nitrification process, and resulted in higher content of nitrate nitrogen. [Conclusions] Based on the C/ N as 25/1, the organic material can enhance the activities of the enzyme which are related to carbon and nitrogen cycle, adjust the chemical components in the tobacco leaves and improve the content of the nutrition in soil. Biochar application can improve the C and N metabolism and then lead to more harmonious chemical components in the tobacco leaves, and promote the quality of tobacco; while the pig manure provided more available nutrition contents in the soil.