宁南黄土丘陵区侵蚀沟不同部位植物多样性与土壤养分

Plant Diversity and Soil Nutrients in Different Parts of Erosion Gully in Loess Hilly Region of South Ningxia

[目的]探明宁南黄土丘陵区侵蚀沟不同部位植物多样性与土壤养分的关系,为侵蚀沟的水土保持及防护提供依据。[方法]以宁夏彭阳县玉洼流域3个稳定侵蚀沟的沟头、沟床、沟岸为对象,通过野外植被调查,同时采集0—10,10—25,25—40,40—55,55—70 cm土样,在室内测定土壤有机碳、土壤全氮、土壤全磷含量,分析了侵蚀沟不同部位(沟头、沟床、沟岸)的植物多样性及土壤养分特征。[结果]侵蚀沟沟头植物隶属3科6属,禾本科4属4种,伞形科和豆科各1属1种;沟床植物隶属5科12属,禾本科4属4种,菊科5属5种,豆科、茜草科和伞形科各1属1种;沟岸植物隶属3科7属,禾本科4属4种,豆科2属2种,伞形科1属1种。侵蚀沟各部位植物种数表现为:沟床>沟岸>沟头,均以禾本科植物为主。生活型上,各部位均以多年生草本植物搭配一、二年生草本植物为主。侵蚀沟的地上生物量、Shannon-Wiener指数、Patrick指数和Margalef指数均表现为:沟床>沟岸>沟头;Simpson指数表现为:沟头>沟床>沟岸;Pielou指数表现为:沟头>沟岸>沟床。侵蚀沟各部位平均土壤有机质、土壤全磷和土壤全氮含量均表现为:沟床>沟岸>沟头,且主要集中在0—10 cm和55—70 cm。侵蚀沟沟头和沟岸的地上生物量与土壤有机碳呈极显著正相关(p<0.01)、与土壤全磷呈显著正相关(p<0.05);侵蚀沟沟床的Shannon-Wiener指数与土壤全磷呈显著负相关(p<0.05),地上生物量与土壤有机碳呈极显著正相关(p<0.01)。[结论]侵蚀沟沟头易崩塌且土壤养分条件较差,应配置根系发达、茎干粗壮、耐冲性强的乡土树种,沟床、沟岸养分较高可优先配置碳、氮、磷含量需求较大的草本或灌木。

[Objective]The aims of this study are to explore the relationship between plant diversity and soil nutrients in different parts of erosion gully in the loess hilly region of south Ningxia,and to provide basis for soil and water conservation and protection of erosion gully.[Methods]The gully head,gully bed and gully bank of three stable erosion gully in Yuwa catchment,Pengyang County,Ningxia were selected as the sites.Soil samples of 0—10,10—25,25—40,40—55,55—70 cm were collected through field vegetation investigation,and the contents of soil organic carbon,soil total nitrogen and soil total phosphorus were measured indoors.Plant diversity and soil nutrient characteristics were analyzed in different parts of erosion gully(gully head,gully bed and gully bank).[Results]In gully head,the plants belong to 3 families and 6 genera,including 4 genera and 4 species of Gramineae,1 genus and 1 species of umbelliferae and legumes.In gully bed,plants belong to 5 families and 12 genera,including 4 genera and 4 species of gramineae,5 genera and 5 species of Compositae,1 genus and 1 species of legumes,rubiaceae and umbelliferae respectively.In Gully bank,plants belong to 3 families and 7 genera,4 genera and 4 species of Gramineae,2 genera and 2 species of legumes,1 genus and 1 species of umbelliferae.The number of plant species in each part of erosion gully is the order:gully bed>gully bank>gully head.With respect to the life type,all parts were mainly perennial herbs with one or two annual herbs.Above-ground biomass,Shannon-wiener index,Patrick index and Margalef index of erosion gully are the order:gully bed>gully bank>gully head;Simpson index shows the order:gully head>gully bed>gully bank;The Pielou index is the order:gully head>gully bank>gully bed.The average contents of soil organic matter,soil total phosphorus and soil total nitrogen in each part of erosion gully are the order:gully bed>gully bank>gully head,and mainly concentrated in 0—10 cm and 55—70 cm.The aboveground biomass was positively correlated with soil organic carbon and soil total phosphorus(p<0.05).Shannon-wiener index was negatively correlated with soil total phosphorus(p<0.05),and aboveground biomass was positively correlated with soil organic carbon(p<0.01).[Conclusion]The erosion gully head is prone to collapse and the soil nutrient condition is poor,so native tree species with developed roots,strong stems and strong scour resistance should be deployed.Herbs or shrubs with high carbon,nitrogen and phosphorus content in gully bed and gully bank should be preferentially deployed.