Application of neighborhood interference model in Pinus tabuliformis plantation in eastern Liaoning province
[Background]Pinus tabuliformis is widely distributed in eastern Liaoning province and is one of the main plantations in this area. This paper discusses the interference model of P. tabulaeformis plantation in Wandao Forest Farm of Fushun county, which provides certain quantitative basis for the study of plantation ecosystem in this area, and provides reference for the scientific and effective management and updating of plantation, and maximizes the ecological and economic benefits of plantation.[Methods] Field survey was conducted in Wandao Forest Farm in June 2018. Three sample plots of 20 m×20 m were set up with P. tabuliformis plantation as the research object. By adopting the fixed sample plot survey method, the factors of the cardinal tree and its adjacent body in the sample plot were actually measured. In this study, an improved neighborhood interference model was adopted to calculate neighborhood interference index, and the relationship between interference index and DBH, tree height, habitat utilization ratio (crown width area) and height-to-diameter ratio was discussed.[Results] 1) The interference index of adjacent body of P. tabuliformis in different P. tabuliformis sample plots was between 0.89 and 31.96, and the interference index decreased with the increase of DBH, tree height and habitat utilization ratio, and increased with the increase of height-to-diameter ratio. 2) Stand density also had some influence on interference index. The stand density of sample plot 1 was relatively large, thus the fluctuation range of interference index was larger, and the maximum interference index reached 31.96, the density of sample plot 2 and 3 was small, and the change of interference index was relatively stable. 3) Young trees in stands were disturbed by neighbors and were in an inferior position in the competition for resources and space, and the tall trees were in a dominant position with little interference. 4) The interference index varied with DBH, tree height, habitat utilization rate and height-diameter ratio within a certain range. When the interference index exceeded a certain range of a factor, it tended to be a certain fixed value. Interference index was significantly correlated with DBH, tree height and habitat utilization ratio (P<0.01), but not significantly correlated with height-todiameter ratio (P>0.05).[Conclusions] Through the above studies, it can be seen that the neighborhood interference model can accurately reflect the extent to which the cardinal tree is affected by neighborhood, it is a quantitative index describing the growth status and status of trees, which can be used to guide forest management activities and provide theoretical basis for rational management.
MAO Xurui, XU Penghai, CAO Yue'e, FAN Mengcheng, YANG Jianjun
Experimental study on shear strength of plant roots in open-pit coal mine wastelands
[Background] Plant roots play an important role in maintaining moisture, fixing soil and preventing soil erosion in the process of ecological restoration of abandoned coal mines. With the application of soil-reinforcement by roots technology and the promotion of ecological engineering, the contribution of plant roots to soil stability has attracted extensive attention from scholars around world. In order to investigate the effect of water retention and soil consolidation during the restoration of herb in abandoned coal mine, the influence of water content and root amount of root-soil composite on shear strength was analyzed, comparing the effect of soil moisture and root with soil cohesion and internal friction angle respectively, thus providing a theoretical basis for the ecological restoration of coal mine wasteland.[Methods] Taking the abandoned land of Xigou Coal Mine in Hutubi county, Xinjiang as the research area, 7 plant species of Lolium perenne L., Elymus dahuricus Turcz., Psathyrostachys juncea (Fisch.) Nevski, Festuca elata Keng ex E. Alexeev, Poa annua L., Agropyron cristatum (L.) Gaertn. and Festuca rubra L. were selected for root-soil complex shear strength test and measurement of soil moisture content and root amount.[Results] The moisture content and root content of the root-soil complex mainly influence the shear strength by affecting the soil cohesion, and the effect on the internal friction angle is not significant. The soil cohesion of most root-soil complexes is negatively related to moisture content (except for F. rubra L.), which increases with the root content. The shear strength is linearly related to the normal pressure, but the shear strength of different root-soil composites increases in different account. The tensile strength is as follows:F. elata Keng ex E. Alexeev > A. cristatum (L.) Gaertn. > P. annua L. > F. rubra L. > L. perenne L. > E. dahuricus Turcz. > P. juncea (Fisch.) Nevski. Among them, F. elata Keng ex E. Alexeev has better soil-fixing performance, and A. cristatum (L.) Gaertn. has better soil reinforced effect. Therefore, they are recommended as the first choice for soil-reinforcement plants in the study area. Secondly, P. annua L. and L. perenne L. can be considered. P. juncea (Fisch.) Nevski. has the worst soil-fixing properties;E. dahuricus Turcz. and F. rubra L. are more suitable as solid soil plants in the moister areas.[Conclusions] The results of this study provide theoretical basis for the restoration of abandoned land in Xigou Coal Mine and other similar environments, and have theoretical and practical significance for further discussion on effective prevention and control of soil erosion and soil erosion in abandoned coal mines.
YAN Sheng, YANG Jianying, SHI Changqing, ZHANG Luyao, ZHAO Tingning
Soil nutrient evaluation of iron tailings in different vegetation restoration modes based on AHP-PCA
[Background] Iron tailings wasteland is one of the most degraded site types caused by the violent disturbance of mining activities. Studies have shown that vegetation restoration can significantly improve soil properties and nutrient content as one of the effective methods for soil reclamation. It is of great significance for soil conservation to evaluate and study soil nutrients of vegetation restoration mode. At present, the sole use of the mainstream evaluation method cannot completely reflect the characteristics of the evaluation object, because the results are affected by the subjectivity of method and the error of the sample difference. This work is to explore the effects of different vegetation restoration modes on soil nutrient recovery in iron tailings wasteland.[Methods] The pH, organic matter, available nitrogen, available phosphorus and available potassium of 6 restoration modes (Castanea mollissima + Juglans regia, C. mollissima + Crataegus pinnatifida, C. mollissima, Pinus tabuliformis + Amygdalus persica, P. tabuliformis + Amorpha fruticosa, A. persica + A. fruticosa) and bare soil were evaluated by evaluation model which combined the weight of analytic hierarchy process (AHP) and principal component analysis (PCA). The above nutrient indexes were obtained by experiment from soil samples of different vegetation modes in the study area.[Results] 1) The trend of soil nutrient recovery in the 6 modes showed that the pH value was improved well, rich in available potassium, medium in available nitrogen, lacking in available phosphorus and organic matter. The nutrient score of the 6 modes was 2.66 -3.40 times higher than the soil of bare land, the highest score of C. mollissima + J. regia mode was 5.61 grade "Credit", in which the soil pH value and organic matter were significantly improved. However, there were significant differences in nutrients between different soil layers in this mode, which indicated the improvement of soil nutrient by vegetation restoration mode was achieved from the surface layer to the deep layer. The evaluation score of A. persica + A. fruticosa mode was 5.40 grade "Credit", which was superior to other modes in the recovery of available phosphorus and potassium.[Conclusions] It is suggested that the mode of C. mollissima + J. regia mixed forest should be adopted to restore the abandoned tailing land. Meanwhile, leguminous deciduous shrubs should be selected to be planted under the forest and phosphorus fertilizer should be applied timely and appropriately to accelerate the recovery of organic matter and available phosphorus. The AHP-PCA evaluation model may reflect the actual situation of the evaluation objects more comprehensively, and the evaluation effect is better than the single method, which has significant practical value for the evaluation of soil nutrients and ecological restoration.
Analysis on the dynamics of the vegetation coverage and the drivers in Taihu Basin via NDVI
[Background] Vegetation is one of the main factors controlling the soil erosion, which can prevent the rainfall splash erosion, improve the soil quality, enhance the erosion durability of soil and decrease the sediment-carrying capacity of surface runoff. Researches on long-term vegetation changes have been conducted in many basins, including Yangtze River Basin, Yellow River Basin, Haihe River Basin, Huai River Basin, Pearl River Basin and Songliao River Basin. However, it is still lack of studies on the spatio-temporal distribution of vegetation in Taihu Basin.[Methods] In this study, we analyzed the changes of the vegetation coverage and their drivers in Taihu Basin at three scales including the whole Taihu Basin, the sub-basins of Taihu Sub-basin and Southeastern-rivers Sub-basin, and some key spots such as the land forms and the regions along the rivers, using normalized difference vegetation index (NDVI) obtained from MOD13 data products and the climatic data of the weather stations. Linear regression models were applied into analyzing the tendency of annual NDVI, and correlation analysis was applied into quantifying the relationship between NDVI and the climatic factors.[Results] 1) There was no significant trend for the annual NDVI in Taihu Basin (P=0.13). But NDVI trend were both significant for the sub-basin. NDVI decreased in Taihu Sub-basin with a rate of-0.004/a (P<0.01), while increased in the Southeastern Rivers Sub-basin with a rate of 0.002/a (P<0.01). 2) In both Taihu Sub-basin and Southeastern Rivers Sub-basin, a decreasing tendency was found in plain, platform and hilly area, while the increasing was found in the mountainous regions. 3) The tendency of the annual NDVI was more obvious in the region distant from water bodies, rather than that closed to water bodies. In the Southeastern Rivers Sub-basin, the increasing trend of NDVI along the distance from water bodies was much stronger than that in Taihu Sub-basin. 4) Climate did not serve as the main factors regulating the NDVI changes except in some mountainous regions where the terrain limited the accessibility of human beings. Contrary to the role of climate, the policies on the afforestation, the increasing population and the urban expansion were the main factors affecting NDVI changes in Taihu Basin.[Conclusions] The results provide a technique reference for soil and water conservation and ecological construction in Taihu Basin. Urban soil and water conservation and supervision of construction projects should be executed in Taihu Sub-basin, while supervision of construction projects, clean small watershed construction and returning farmland to forests should be paid emphasis on in Southeastern Rivers Sub-basin.
Effects of alkaline stress on seed germination and seedling growth of Suaeda salsa
[Background] The salt composition of soda saline-alkali soil is dominated by Na2CO3 and NaHCO3. This type of soil has both salinization and alkalization characteristics. It not only is of strong alkalinity, but also has poor physical and chemical properties, which severely restricts local agricultural production. Planting vegetation adapting to the growth site conditions of soda saline-alkali land is an important measure for the improvement and utilization of soda saline-alkali land. The purpose of this study is to investigate the alkali-tolerant range and alkali-resistance properties of Suaeda salsa.[Methods] Using S. salsa seeds as test materials, NaHCO3 and Na2CO3 were mixed at a molar ratio of 9:1, and a total of 6 treatment concentrations of 0 (CK), 50, 100, 150, 200, and 250 mmol/L were set, respectively. And the experiments was carried out with two culture media of distilled water and soda saline-alkali soil, and the difference of seed germination and seedling growth status of S. salsa were analyzed.[Results] 1) In the experiment with distilled water as the culture medium, the germination potential, germination rate and germination index of S. salsa seeds were significantly lower than that of CK when the alkali concentration was > 150 mmol/L, and the length of the embryo, the length of the radicle and the seed vigor index were significantly lower than that in CK when the alkali concentration was > 100 mmol/L. 2) In the experiment with soda saline-alkali soil as the culture medium, when the alkali concentration was > 200 mmol/L, the germination rate and seedling surviual rate of S. salsa seeds significantly reduced by 19.36% and 38.10% compared with CK, respectively; under 50 and 100 mmol/L alkali concentration treatment conditions, the young shoot length significantly increased by 23.82% and 19.96% compared with CK, and the young root length of S. salsa was significantly lower than that of CK when the alkali concentration was > 50 mmol/L. 3) The results of redundancy analysis showed that soil EC value and total alkalinity were the main factors affecting the growth of S. salsa, and the degree of interpretation was 48% and 41.1%, respectively; and there was a significant negative correlation with the growth indexes of S. salsa.[Conclusions] The seed germination and seedling growth of S. salsa can tolerate a certain range of alkali stress, and the alkali resistance range of S. salsa in the soda saline-alkali soil is higher than that in distilled water.
Soil erodibility K values and its distribution in Anhui province
[Background] Soil erosion is the concentrated embodiment of environmental problems in China. Erosion intensity is affected by external factors, such as rainfall, topography and vegetation, and also depends on soil anti-erosion ability. Soil erodibility is a main index of soil erosion resistance. And it is also the basic data for soil erosion prediction. The veracity of soil erodibility value directly affects soil erosion prediction accuracy. The vegetation of Anhui province was fatal damaged and the soil loss on the surface was severe in 1950s and 1960s. At present, although natural secondary forest has been restored in a large range, 12 400 km2 of soil erosion area still exists, especially for sloping farmland, economic woodland and sparse woodland due to heavy rainfall, complex topography, and frequent human activities. Therefore, in order to protect soil resources and achieve sustainable development of the area, the soil erodibility of the region needs to be studied.[Methods] This study analyzed the soil erodibility and its distribution using universal soil loss equation, EPIC model, soil texture transformation method, and ArcGIS software. Data of precipitation, soil erosion and soil properties were collected from 4 experimental stations of soil and water conservation in Anhui province. Data of 48 typical profiles for Anhui province were collected from "soil distribution of Anhui province" and "Chinese soil record" books. The soil samples were collected on sunny days. Fifteen soil cores were collected using "S" road from the topsoil (0-20 cm) of each plot and were mixed completely to produce a composite sample for each plot. Plant roots and large stones were removed by sieving through a 2 mm mesh, and all soil samples were then stored at 4℃ until analyses of soil texture and chemical properties.[Results] There were 10 main soil types covering 92.3% of the total area in Anhui province. Main soil types in the erosional region were red soil, skeleton soil, yellow cinnamon soil, yellow brown soil, yellow soil and purple soil, which covered 44.9% of the total area in the province. There was a fine linear relationship between the measured values and estimated values of the EPIC model for the soil erodibility. The built linear equation thus revised the estimated values of EPIC model. The fractal model which was well verified transformed the soil texture composition from international system to American system for Anhui provincial soils. The erodibility value was 0.020-0.050 t·hm2·h/(MJ·mm·hm2) in the soil and water loss region, and the provincial average K value was 0.036 6 t·hm2·h/(MJ·mm·hm2).[Conclusions] The results provide basic data and technical support for the soil erosion prediction, which is of great significance to the protection of land resources and the ecological construction of soil and water conservation in the region.
A review of soil erosion environment and soil and water loss for rural settlement
[Background] Rural settlements are the main places for residents to live and engage in agricultural production, meanwhile it is the important component of the natural environment. The landscape of rural settlement is generally formed by natural elements and human activities. In recent years, along with enhancement of people's awareness on ecological and environmental problems, soil and water loss in rural settlements has raised attention to human in China. The environment of rural settlement is generally formed by natural elements and human labor.[Methods] Through reviewing literatures published in the past and recent years, this study discussed the changes of erosion environment in rural settlements and analyzing the characteristics of soil and water loss.[Results] Soil erosion environment refers to the special landscape and ecosystem formed by soil erosion and, in turn, those landscapes will affect soil erosion. In rural settlements, soil erosion environment includes natural environments (i. e., landforms, water systems, soils, vegetation and others) and human environments (i. e., rural unpaved road, compounds, footpaths, places and others uncovered places). It can be seen that the erosion environment in rural settlements is not only affected by certain natural factors such as water source, slope and rainfall, but also greatly influenced by human factors such as building houses, road construction within villages, farming activities, and so on. All those factors may lead to heavy soil loss in rural settlements. At present, with the development of rural economy, the function of rural settlements has gradually evolved from the original inhabitation-agricultural production type into the multi-dimensional types:Residence, agricultural production, tourism rest and ecological conservation. At the same time, the impact of human factors on the erosion environment in rural settlements became more and more great and hence accelerates soil and water loss. The change of rural function is a direct cause of environmental change and soil erosion increase in rural settlements. Compared to previous conditions, erosion environment in rural settlements is becoming complex and heterogeneous in human disturbance. Finally, these characteristics of erosion environment would cause that the types and amount of soil and water loss are various.[Conclusions] The change of erosion environment and soil and water loss in rural settlements cannot be ignored. However, the research on that is still in the exploratory stage at present, and their characteristics and mechanism are not very clear. Therefore, in order to promote soil and water conservation and ecological environment management in rural settlements, it is urgent to strengthen the research on soil erosion mechanism and prevention technology of different land types in rural settlements. This result will provide a theoretical basis and scientific support for the rural revitalization and the construction of beautiful China in the new era.
