南方红壤丘陵区不同植被类型土壤不同土层水分对降水的响应

以江西省泰和县老虎山小流域为研究对象,使用ECH_2O土壤含水率监测系统,对该区域百喜草(Paspalum notatumn)地、马尾松(Pinus massoniana)林地不同土层土壤含水率进行了定位监测,以裸地作为对照,分析红壤丘陵区百喜草地、马尾松林地各土层土壤水分对不同强度降水的响应。结果表明:(1)降雨后,不同土层深度土壤含水率的变化趋势相同且同一植被各土层土壤含水率从大到小依次为:5、15、30、60 cm土层。(2)同一土层,百喜草土壤含水率增长最快,其次为马尾松,最后为裸地。其中小雨时,,其他土层土壤含水率均有增加(百喜草增加2.42%~3.81%,马尾松增加1.94%~3.10%,裸地增加1.30%~2.34%),60 cm土层无响应;中雨时,百喜草土壤含水率增加1.73%~3.89%,马尾松增加1.56%~3.45%,裸地增加1.41%~2.98%;大雨时,百喜草土壤含水率增加2.94%~8.81%,马尾松土壤含水率增加2.51%~8.10%,裸地土壤含水率增加2.44%~7.67%。(3)土壤含水率主要受降水影响,降雨强度越大,土壤含水率增长速率越快。降雨强度为4.43 mm/h时,5 cm土层土壤含水率增长速率为(0.42%~0.57%)/h,15 cm土层土壤含水率增长速率为(1.91%~2.16%)/h,30 cm土层土壤含水率增长速率为(1.74%~1.98%)/h,60 cm土层无响应;降雨强度为12.74 mm/h时,5 cm土层土壤含水率增长速率(4.41%~4.89%)/h,15 cm土层土壤含水率增长速率为(4.98%~5.41%)/h,30 cm土层土壤含水率增长速率为(2.33%~3.06%)/h,60 cm土层土壤含水率增长速率为(0.34%~0.52%)/h;降雨强度为22.49 mm/h时,5 cm土层土壤含水率增长速率为(5.38%~5.83%)/h,15 cm土层土壤含水率增长速率为(5.60%~6.02%)/h,30 cm土层土壤含水率增长速率为(3.26%~3.61%)/h,60 cm土层土壤含水率增长速率为(1.05%~1.27%)/h。(4)在同一降水类型条件下,百喜草地土壤退水时间最长,其次为马尾松林地,最后为裸地。

Response of Soil Moisture to Rainfall in Pinus massoniana Stands and Paspalum notatumn Glassland in Hilly Red Soil Region of Southern China

ECH2O soil moisture content detection system was used to measure the volumetric soil water content (VSWC) at 5,15,30 and 60 cm depths of Paspalum notatumn grassland and Pinus massoniana stands in hilly areas of southern China.Compare to bare land,the VSWC curves in light,moderate,and heavy rainfall conditions were analyzed.The VSWC curves of different soil depths was the same,and the VSWC increment was in descending order of soil layer of 5,15,30 and 60 cm under the same vegetation cover.The growth rate of VSWC was in descending order of P.notatumn grassland,P.massoniana stands and bare land at the same soil layer,among them,in case of light rainfall,the VSWC at other soil layers was increased except for 60 cm soil layer.The VSWC of P.notatumn grassland increased about 2.42％-3.81％,about 1.94％-3.10％ of P.massoniana stands,and 1.30％-2.34％ in bare land.During the moderate rainfall,the VSWC of P.notatumn grassland was increased by 1.73％-3.89％,1.56％-3.45％ of P.massoniana stands,and 1.41％-2.98％ in bare land.During the heavy rainfall,the VSWC of P.notatumn grassland was increased by 2.94％-8.81％,2.51％-8.10％ of P.mossoniana stands,and 2.44％-7.67％ in bare land.The VSWC was mainly affected by precipitation,the higher the rain intensity,the faster the growth rate of VSWC.When the rainfall intensity of 4.43 mm/h,the VSWC growth rate of 5cm soil layer was 0.42％-0.57％/h,1.91％～2.16％/h for 15 cm soil layer,1.74％-1.98％/h for 30 cm soil layer,and no response for 60 cm soil layer,respectively.When rainfall intensity of 12.74 mm/h,the VSWC growth rate of 5 cm soil layer was 4.41％-4.89％/h,4.98％-5.41％/h for 15 cm soil layer,2.33％-3.06％/h for 30cm soil layer,and 0.34％-0.52％/h for 60 cm soil layer,respectively.When the rainfall intensity was 22.49 mm/h,the VSWC growth rate of 5 cm soil layer is 5.38％-5.83％/h,5.60％-6.02％/h for 15 cm soil layer,3.26％-3.61％/h for 30 cm soil layer,and 1.05％-1.27％/h for 60 cm soil layer.Under the same rainfall type,the time of the VSWC return stable state of P.notatumn grassland was the longest,followed by P.massoniana stands and bare land.