Analysis of factors influencing soil moisture changes
Changes in soil moisture are affected by many factors, such as rainfall, plant growth and absorption, loss of topographic moisture, human activities, and so on. Today, we use a soil moisture analyzer to measure the soil moisture changes in a certain area of ​​Chengdu, in order to find out the factors that affect the soil moisture.
1. The spatial variability of soil moisture shows a decreasing trend as plants grow stronger and stronger.
The mean value of soil moisture in the study area was between 7.03% and 20.25%, and gradually increased with the increase of soil depth. The soil moisture of all layers was moderately variable, and the coefficient of variation was the lowest in the surface layer (0-20 cm) and the largest in the 60-80 cm soil layer. During the whole growing season of plants, the spatial heterogeneity of above-ground biomass is very large. When the hydrothermal conditions are sufficient, the spatial variability of above-ground biomass shows a decreasing trend as the growth of plants becomes more and more vigorous.
2. Topographic factors have different effects on soil moisture content at different depths.
Among them, the spatial differentiation of soil moisture in 20-40cm and 60-80cm has a very significant effect, and it has a significant effect on the spatial differentiation of 0-100cm average soil moisture content. The seasonal dynamics of the average soil moisture content from 0 to 100 cm is affected by a combination of environmental factors including rainfall. The spatial-temporal distribution of soil moisture generated by Kriging interpolation method reflects the variation of soil moisture under three kinds of topography. The soil moisture change rate of hill slope is the largest; the soil moisture change rate is relatively low in the 0-30cm of the hill top; The stable layer of soil moisture is deeper than the top of the hill and the slope of the hill, and the infiltration speed and depth of the soil moisture in the inter-pile land after rainfall are large. Rainfall during the initial stages of growth is basically lost due to evaporation and transpiration, and rainfall at the end of growth has a certain accumulation in the soil.
3. The topography is not the main influence factor for the spatial differentiation of above-ground biomass in the region.
There are significant differences in the dynamics of plant growth under the three types of terrain. First, the peak biomass of the hilly slope and inter-duneland lags behind the top of the hill; secondly, the high temperature and drought stress has little influence on the normal growth of the inter-dipping land plants, but it has a great influence on the top vegetation of the hill; finally, the larger concentration of rainfall There is a certain erosion effect on the vegetation of Qiupo, which affects its normal growth.
4. Rainfall supplements soil moisture.
In areas with severe water deficits, plant growth water consumption cannot be supplemented by rainfall, and the longer-reaching regions have greater water consumption, indicating a negative correlation between cumulative biomass and soil moisture.
The Pearson correlation coefficient shows the correlation between soil moisture and above-ground biomass at different growth stages. The soil moisture content is an important factor in the early stage of plant growth, and the growth water consumption mainly comes from the 60-100 cm soil layer; the growth period and the end of growth period The correlation between soil moisture and aboveground biomass is weak.
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