林草复合系统的生态学及经济学效益评价

An analysis of economic benefit and social effect of Pi Te apple-alfalfa complex ecosystem

综合分析和评价了啤特果树Pyrusussurignsis-紫花苜蓿Medicagosativa、啤特果树-小麦Triticumaestivum两种复合系统的生态学效应和经济效益。结果表明：啤特果树-紫花苜蓿复合系统和啤特果树-小麦复合系统的土壤客重分别为1．39和1．45g／cm^3。啤特果树-紫花苜蓿复合系统中非毛管孔隙度（4．72％）和总孔隙度（58．96％）均大于啤特果树一小麦复合系统中非毛管孔隙度（4．15％）和总孔隙度（50．80％），说明林下种植紫花苜蓿较种植小麦更有利于疏松土壤、改良土壤结构；啤特果树-紫花苜蓿复合系统的不同土壤层土壤含水量均大于啤特果树-小麦复合系统的土壤含水量，说明林下紫花苜蓿比小麦的保水蓄水能力强；紫花苜蓿和小麦的茎叶持水率分别为37．3％和25．8％，说明林下紫花苜蓿更能减少地表径流，从而减轻水土流失；紫花苜蓿}E小麦更能有效地缓解地面温度的激增和激减；种植紫花苜蓿比种粮食作物多收入8900～8850元／hm^2。因此林下种植紫花苜蓿较种植小麦具有显著的生态效益和经济效益。

The objective of this research was to compare the ecologic and economic benefit of Pi Te apple （Pyrus ussuriensis） -- alfalfa （Medicago sativa） and wheat （Triticum aestivum） -- alfalfa complex ecosystem in Linxia, Gansu Province. Soil bulk density was 1.39 and 1.45 g/cm^3 , non-capillary porosity was 4.72% and 4.15%, and overall porosity was 58.96% and 50.80%, respectively. Soil holding water capacity in the first ecosystem was higher than that in the second. Water-holding rate in leaves-stems of alfalfa and wheat was 37.3% and 25.8%. Income in the first ecosystem was more than the second. These indicate M. alfalfa are more beneficial to the soil conservation and economic development than wheat in the apple ecosystems.