采煤塌陷影响下土壤含水量变化对柠条气孔导度、蒸腾与光合作用速率的影响

采煤塌陷引起的土壤环境因子的变化对矿区植物生长的影响越来越受到人们的关注,气孔导度、蒸腾与光合作用作为环境变化响应的敏感因子,研究植物气孔导度、蒸腾与光合作用的变化是揭示荒漠矿区自然环境变化及其规律的重要手段之一。研究采煤塌陷条件下植物光合生理的变化是探究煤炭开采对植物叶片水分蒸腾散失和CO_2同化速率影响的关键环节,是探讨采煤塌陷影响下植物能量与水分交换动态的基础,而采煤矿区植物叶片气孔导度、蒸腾与光合作用速率对采煤塌陷影响下土壤含水量变化的响应如何尚不清楚。选取神东煤田大柳塔矿区52302工作面为实验场地,以生态修复物种柠条为研究对象,对采煤塌陷区和对照区柠条叶片气孔导度、蒸腾和光合作用速率以及土壤体积含水量进行监测,分析了采煤塌陷条件下土壤含水量的变化以及其对柠条叶片气孔导度、蒸腾与光合作用速率的影响。结果显示:(1)煤炭井工开采在地表形成大量裂缝,破坏了土体结构,潜水位埋深降低,土壤含水量均低于沉陷初期,相对于对照区,硬梁和风沙塌陷区土壤含水量分别降低了18.61%、21.12%;(2)柠条叶片气孔导度、蒸腾和光合作用速率均与土壤含水量呈正相关关系;煤炭开采沉陷增加了地表水分散失,加剧了土壤水分胁迫程度,为了减少蒸腾导致的水分散失,柠条叶片气孔阻力增加,从而气孔导度降低,阻碍了光合作用CO_2的供应,从而导致柠条叶片光合作用速率的降低,蒸腾速率也显著降低。

Effects of soil water content on stomatal conductance, transpiration, and photosynthetic rate of Caragana korshinskii under the influence of coal mining subsidence

Increased attention has been paid to the influence of environmental factors caused by coal mining subsidence on plant physiology. Stomatal conductance, transpiration and rate of photosynthesis are factors sensitive to the environment, therefore it is important to study of the change in stomatal conductance, transpiration, and photosynthetic rate to reveal the change of natural environment in the mining area. Investigation of the changes in stomatal conductance, transpiration, and photosynthetic rate under the condition of coal mining subsidence is a key step to explore the effects of coal mining on water transpiration and CO₂ assimilation rate. It is concluded that the relationships between stomatal conductance, transpiration, and photosynthetic rate and environmental factors in coal mining subsidence areas are the basis of the relationship between energy and water exchange under the influence of coal mining subsidence. However, the responses of stomatal conductance, transpiration, and photosynthetic rate to the change in soil water content are not clear in coal mining subsidence areas. The 52302 working face of the Daliuta mining area was selected as the experimental site, with Caragana korshinskii as the research object. Stomatal conductance, transpiration and rate of photosynthesis in C. korshinskii leaves and soil water content were monitored in a coal mining subsidence area and a non-collapse area. The characteristics of the responses of stomatal conductance, transpiration, and photosynthetic rates of C. korshinskii leaves to soil water content were analyzed. The results show that:(1) Coal mining resulted in surface cracking, soil structure damage and diving depth reduction. Soil water content was lower than that in the early stage of the subsidence. Compared with the control area, the soil moisture contents of the hard ground and the aeolian sandy land subsidence area were decreased by 18.61% and 21.12%, respectively. (2) The stomatal conductance, transpiration, and photosynthetic rate of C. korshinskii leaves were positively correlated with soil water content. Subsidence of coal mining area increased the loss of surface water and intensified the degree of soil water stress. In order to reduce transpiration caused by water loss, C. korshinskii leaf stomatal resistance increased, stomatal conductance decreased, and CO₂ supply for photosynthesis was hindered, which led to the reduced C. korshinskii leaf photosynthetic and transpiration rates.