海拔及旅游干扰对武功山山地草甸土壤渗透性的影响

Effects of elevation and tourism disturbance on meadow soil infiltration on Wugong Mountain

土壤渗透能力是影响土壤侵蚀的重要因素之一,是反映土壤水源涵养及调节功能的重要指标,目前对于亚热带山地草甸土壤渗透性方面研究较少。江西武功山草甸是亚热带山地草甸的典型代表,以面积广和分布基准海拔低的特点,在华东植被垂直带谱中具有典型性和特殊性,但是人为干扰和过度旅游开发使武功山脆弱的山地草甸出现严重退化和破碎化态势。以武功山不同海拔及旅游干扰程度山地草甸土壤为研究对象,分别测定0—20 cm和20—40 cm土层土壤的初渗率、稳渗率、平均入渗率、前60分钟渗透总量、温度、湿度、容重、最大持水量、最小持水量、毛管持水量、pH、有机质、速效氮、速效磷、速效钾等理化指标,分析不同海拔及干扰程度草甸土壤渗透性特征,探讨影响土壤渗透性的相关因子,为亚热带地区退化草甸的修复及可持续经营提供参考。结果表明:(1)1600—1800 m范围,随着海拔升高,土壤渗透性呈降低趋势,在1900 m范围土壤渗透性又有所提高,各海拔土壤渗透性排序为1600 m>1700 m>1900 m>1800 m。(2)随着干扰程度增强,草甸土壤渗透性呈降低趋势,各干扰程度的土壤渗透性排序为无干扰>轻度干扰>中度干扰>重度干扰。(3)所有草甸分布区0—20 cm土层的土壤渗透性均高于20—40 cm土层,初渗率>平均入渗率>稳渗率。(4)通用经验模型更适合武功山草甸土壤水分入渗过程,Horton模型次之,Philip模型和Kostiakov模型拟合效果都比较差。(5)土壤渗透性与土壤湿度、毛管持水量呈显著正相关(P<0.05),与容重呈显著负相关(P<0.05),初渗率及平均入渗率与速效氮含量显著正相关(P<0.05),稳渗率、平均入渗率、渗透总量与速效钾含量呈显著正相关(P<0.05)。

Soil infiltration capacity is one of the most important factors affecting soil erosion and is an important indexreflecting soil water conservation and regulation function. The Wugong Mountain meadow is a representative subtropical mountain meadow in Jiangxi Province,which is in the typical and special vertical vegetation zone of East China. However,human disturbance and excessive tourism development caused serious degradation and fragmentation of this fragile mountain meadow. This study evaluated the alpine meadow soil infiltration capacity at different elevations and disturbance levels from the fringe meadow upwards to the top in Wugong Mountains. Set an elevation gradient experiment treatment at intervals of about 100 m,four experiment treatments namely 1600 m,1700 m,1800 m,and 1900 m. In addition,according to the loss of vegetation coverage caused by tourism disturbance,set four disturbance experiment treatments which included the no disturbance（ control check,abbreviation was CK,vegetation coverage rate ≥ 90%）,light disturbance（ LD,60% ≤vegetation coverage rate 〈90%）,medium disturbance（ MD,30% ≤ vegetation coverage rate 〈60%）,and severe disturbance（ SD,vegetation coverage rate 〈30%）. Various indices including the soil initial infiltration rate,steady infiltration rate,average infiltration rate,total infiltration of the first 60 min,soil temperature,soil humidity,soil bulk density,maximum water holding capacity,minimum water holding capacity,capillary water holding capacity,p H,organic matter,available nitrogen,available phosphorus,and available potassium were measured in two soil layers,0-20 cm and20-40 cm,to analyze soil infiltration characteristics at different elevations and disturbance levels and to be able to discuss the factors that affect the soil infiltration and provide references for the ecological restoration and sustainable management of degraded meadows in the subtropical zone. The results showed that（ 1） as elevation increased,soil infiltration decreased at elevations in the 1600-1800 m range,but increased at 1900 m. The amount of soil infiltration from highest to lowest was1600 m〉1700 m〉1900 m〉1800 m.（ 2） As disturbance level increased,soil infiltration decreased,and the amount of soil infiltration from highest to lowest was CK 〉LD 〉MD 〉SD.（ 3） Soil infiltration of the upper layer（ 0-20 cm） was higher than that of the lower layer（ 20-40 cm）,and infiltration rate from highest to lowest was initial infiltration rate average infiltration ratesteady infiltration rate.（ 4） The common empirical infiltration model was the most suitable representation of the infiltration process of meadow soil moisture in the Wugong Mountains,followed by the Horton model,whereas the Philip and Kostiakov models were not suitable.（ 5） Soil infiltration and capillary water-holding capacity were significantly positively correlated（ P〈0.05）,and was significantly negatively correlated with soil bulk density（ P〈0.05）. Available nitrogen content was significantly positively correlated with initial infiltration rate and average infiltration rate（ P〈0.05）,and available potassium content was significantly positively correlated with the steady infiltration rate,average infiltration rate,and with total infiltration（ P〈0.05）.