【摘要】 为客观认识北京市森林生态系统的土壤保持功能,选用植被覆盖度、枯枝落叶厚度、林分类型、郁闭度和群落结构等5项指标,综合评价了北京市森林土壤保持能力的相对大小。结果表明:北京市森林生态系统的土壤保持能力较高,其中65.7%的森林保持土壤能力为中等以上,16.8%的森林保持土壤能力较低;不同区县森林的保土能力存在差异,其中石景山区的森林保土能力最高,其次为延庆县、密云县和门头沟区,而大兴区森林的保土能力最低;随着海拔高度增加,森林保持土壤的能力升高,即中山区(海拔>800m)森林的保持土壤能力最大,而平原区(海拔<100m)森林保持土壤能力较低;地形坡度增大,森林保持土壤能力也增加,不过坡度25°以上森林的保土能力接近;林地土壤类型不同,森林保持土壤能力也不同,其中土壤类型为山地棕壤、山地草甸土和褐土的森林保土能力较高,而为水稻土、潮土、风砂土和草甸沼泽土的森林保土能力较低。更多还原

【Abstract】 In this paper,five factors such as vegetation cover ratio,the depth of forest floor,forest type,crown density and community structure were employed to comprehensively evaluate Beijing’s forest ecosystems effects on soil conservation.The results showed that 65.7% of forests in Beijing had the soil conservation ability at the middle and higher level,16.8% at low level.The capacity of soil conservation in Beijing’s forests varied greatly in different districts(or counties),and was ranked in the descending order as follows:Shijingshan District,Yanqing County,Miyun County,Mentougou District,Fangshan District,Haidian Distrcit,Pinggu District,Changping District,Fengtai District,Huairou District,Chaoyang District,Shunyi District,Tongzhou District and Daxing District.The capacity of soil conservation in Beijing’s forests had a positive relationship with altitude,and was ranked from low to high as plain area(less than 100 m),hilly area(between 100 and 500 m),low mountain(between 500 and 800 m)and middle mountain(more than 800 m).With the increasing slope,the soil conservation ability of forests increased slightly,however,when slope more than 25 degree,there was little differences of soil conservation capacity.The capacity of soil conservation also varied with forest soil type,those forests with mountain meadow soil,mountain brown earth and cinnamon soil had the higher level,and paddy soil,alluvial soil,aeolian soil and meadow-boggy soil had lower level.更多还原