红壤丘陵区苔藓结皮土壤分离能力季节变化特征

Seasonal variation of soil detachment capacity induced by moss crusts in red soil hilly area

土壤分离是土壤侵蚀的初级阶段,受植物根系、生物结皮的生长等影响,可能存在明显季节变化。而南方红壤丘陵区水热资源丰富,生物结皮在林下广泛存在,势必会影响林下水土流失过程。以红壤丘陵区樟树林和油茶园内苔藓结皮为对象,研究了苔藓结皮土壤分离能力季节变化特征及主控因素。结果表明:(1)苔藓结皮表面特征随季节变化显著,水热条件适宜时,苔藓结皮表面特征发育良好;降雨减少干旱时,苔藓结皮开始退化。(2)随着苔藓结皮盖度、厚度、株高和黏结力增加,土壤抗蚀性能增强,土壤分离能力下降;细沟可蚀性与土壤分离能力变化趋势一致,均随苔藓结皮发育程度增加而减小;干旱时苔藓结皮退化有滞后效应,土壤分离能力迅速增大后再缓慢增大。(3)采用水流剪切力、结皮盖度、土壤黏结力等来模拟土壤分离能力的季节变化,通过拟合方程可以较好地解释区域内经果林下苔藓结皮发育对土壤分离能力的季节变化,模型精度(NSE=0.728)表明该模型在预测和解释土壤分离能力变化方面具有较好效果。研究苔藓结皮季节动态及分离能力变化可为南方红壤丘陵区的水土流失防治提供重要的科学依据。

Soil detachment,the initial stage of soil erosion,is considerably affected by the growth of plant roots and biological crusts,resulting in potential seasonal variations in soil detachment.In the red soil hilly region in southern China,,biological crusts develop extensively beneath the forest canopies due to the richness of hydrothermal resources,therefore inevitably impacting the process of soil erosion in this area.The study selected the moss crusts within the camphor forest and oil tea plantation in the red soil hilly region as the research subjects,investigating the seasonal variations in the soil detachment capacity of moss crusts and their main influencing factors.The results showed that:(1)the surface characteristics of the moss crusts varied significantly with the seasons.When hydrothermal conditions were favorable,the surface characteristics of the moss crusts were well developed,and the moss crusts began to deteriorate when rainfall decreased and drought set in.(2)As the coverage,thickness,and plant height of the moss crusts,as well as soil cohesion,were increased,soil erosion resistance rose,whereas soil detachment capacity diminished.Both rill erodibility and soil detachment capacity were declined by the development of the moss crusts.During the drought,there was a hysteresis effect in the soil detachment capacity after the degradation of moss crusts,with the soil detachment capacity first rapidly increasing and then gradually increasing.(3)The seasonal variations in soil detachment capacity could be estimated with power functions of flow shear stress,soil cohesion,and biological crust coverage.It effectively elucidated the seasonal changes in soil detachment capacity caused by moss crusts development under economic forests in the region.The model accuracy(NSE=0.728)indicated that it was effective in predicting and explaining changes in soil detachment capacity.This study′s investigation into the seasonal dynamics of moss crusts and the associated variations in soil detachment capacity may provide an important scientific basis for the prevention and control of soil erosion in the red soil hilly region of southern China.