宁南带状柠条林地根系及土壤水分养分分布特征

Distribution Characteristics of Root,Soil Moisture and Nutrients in Caragana korshinskiiForest Strip Land in Southern Ningxia

为探究宁夏南部黄土丘陵区柠条人工林地根系、土壤水分、土壤N、P养分特征,采用野外调查与室内分析相结合的方法,对宁南黄土丘陵区人工种植20 a的柠条林地0~1000 cm土壤中根系垂直分布、土壤水分、土壤N、P含量(质量分数,下同)变化进行分析。结果表明:1)柠条林地0~1000 cm土壤水分消耗量大,土壤储水量较旱作农田减少919.84 mm,平均每年较旱作农田耗水增加45.99 mm,为柠条林地深层土壤干化的直接原因;2)柠条林地根系主要集中在0~80 cm土层,该层根系(表面积密度)占0~1000 cm根系总量的62.4%;3)柠条林地土壤N、P养分分布规律与根系分布规律一致,即表层多深层少,0~200 cm土层内全N含量平均值为0.53 g·kg^(-1),是0~1000 cm土壤全N含量平均值1.86倍,全P含量平均值达0.52 g·kg^(-1),与0~1000 cm土层全P含量平均值近似。研究结果对于深入了解半干旱黄土区柠条人工林地根系、水分与养分关系及可持续经营具有积极意义。

To explore the characteristics of the distribution of roots,soil water and soil nutrients(N and P),20-year-old Caragana korshinskii plantations were used as the research object in the Loess hilly regions of southern Ningxia.Field sampling and laboratory analysis methods were applied to analyze the vertical distribution of roots,soil water and the contents of soil N and P in 0-1000 cm deep range.The results showed that 1)the 0-1000 cm deep soil of 20-year-old C.korshinskii plantation had high soil water consumption and the soil water storage was 919.84 mm less than that in the dry farmland.The average annual water consumption was 45.99 mm higher than that in the dry farmland,which directly caused deep dried soil layers in C.korshinskii plantations.2)The roots were mainly concentrated in 0-80 cm soil layers,accounted for 62.4%of total root biomass in 0-1000 cm depth.3)The distribution of soil N and P for C.korshinskii woodland was consistent with roots distribution.The average total N content in 0-200 cm soil layers was 0.53 g·kg^(-1),which was 1.86 times of the average total N content in 0-1000 cm layers.The average total P content was 0.52 g·kg^(-1),which was close to the average total P content in 0-1000 cm layers.This study has positive effects on better understanding the relationship between roots,water and nutrients and provides sustainable management strategies for artificial C.korshinskii plantations in semi-arid Loess regions.