大兴安岭林区不同植被对冻土地温的影响  

Influence of vegetation on frozen ground temperatures the forested area in the Da Xing′anling Mountains,Northeastern China

作　　者：常晓丽[1] 金会军[1] 于少鹏[1,2] 孙海滨 何瑞霞[1] 罗栋梁[1] 孙广友[4] 吕兰芝[1] 

机构地区：[1]中国科学院寒区旱区环境与工程研究所冻土工程国家重点实验室,兰州730000 [2]哈尔滨学院地理系,哈尔滨150086 [3]根河市气象局,根河022350 [4]中国科学院东北地理与农业生态研究所,长春130062

出　　处：《生态学报》2011年第18期5138-5147,共10页Acta Ecologica Sinica

基　　金：全球变化研究国家重大科学研究计划项目(2010CB951402);国家自然科学基金(40701031);国家自然基金创新群体项目(40821001);冻土工程重点实验室专项子课题(SKLFSE-ZT-01);冻土工程国家重点实验室开放基金课题(SKLFSE200902)共同资助

摘　　要：植被常常通过反射太阳辐射、遮阳、蒸腾散热、阻风挡雪、保水吸水等来影响下伏多年冻土。但是不同的植被类型,对下伏冻土热状况的影响也不尽相同。为了探讨大兴安岭林区不同植被对冻土的影响,选取大兴安岭森林生态站实验区杜香-真藓-落叶松林、真藓-落叶松林、塔头-落叶松林、柴桦落叶松林和伊图里河镇原冻土观测场塔头湿地5种典型林型,分析不同林型对冻土的温度和冻融作用的影响。研究发现不同林型的不同组分,由于反射率、覆盖度和根系吸水能力的差别,使得各种林型下的地面温度也不相同。在夏季,月平均地面温度从高到低依次为真藓-落叶松林、杜香-真藓-落叶松林、伊图里河塔头湿地、柴桦落叶松林和塔头落叶松林。由于塔头落叶松林存在乔木层和灌木层,与伊图里河塔头湿地相比,8月份平均地面温度差值低10℃以上。柴桦落叶松林两个钻孔的对比实验表明,铲除地表植被会使活动层0.8 m以上部分的地温升高,并且主要发生在8、9、10月份。对冻土而言,林区植被暖季降温的贡献大于冷季增温的贡献。另外,塔头-落叶松林根系吸水能力最强,这种林型下的土壤开始融化和冻结的日期最晚,冻结初期地面降温速率为0.1℃/d,而0.2 m以下降温速率几乎为零。同样柴桦落叶松林的塔头根系吸水能力使得其0.5 m和0.8 m的降温速率低于除塔头落叶松林外的其他林型,但是地面上植物的凋零和枯萎会加快地面的冻结速率。真藓-落叶松林的乔灌木层发育不好,地面降温速率大于杜香-真藓-落叶松林和伊图里河塔头湿地,而伊图里河塔头湿地由于没有乔灌木层的庇护,地面以下的降温速率高于其他林型。In the Da Xiang′anling Mountains,vegetation has relatively high albedo,surface coverage,and capability for water holding and retention,which have large impacts on the thermal regime in soils and permafrost hydrology.In order to understand the influences of different types of forests on frozen ground temperatures and the freeze-thaw processes,five respresentative forests,including a Ledum palustre var.dilatatum-Bryum-Larix dahurica forest,a Bryum-L.dahurica forest,Betula fruticosa L.dahurica forest,and a Carex tato-L.dahurica forest in the experimental area at the China Forest Ecological Research Network（CFERN） Station near Genhe in the Da Xing′anling Mountains,and a Carex tato swamp in the nearby Yitulihe,were chosen for monitoring ground temperatures in the active layer with depths from ground surface to 1.6 m and at shallow depths in permafrost. Ground surface temperatures vary considerably due to the combined influences of albedo,coverage and capability of water holding and retention in these five types of forest.In summer,the mean monthly ground surface temperatures decline in the order of the Bryum-L.dahurica forest,the Ledum palustre var.dilatatum-Bryum-L.dahurica forest,the Carex tato swamp,the Betula fruticosa L.dahurica forest,and the Carex tato- L.dahurica forest.Due to the shading effect of larch stands and shrubs,the mean monthly ground surface temperature of the Carex tato- L.dahurica forest is about 10 ℃ lower than that of the Carex tato swamp.In addition,ground temperature monitoring was carried out in the Betula fruticosa L.dahurica forest between two boreholes.At one of which the aboveground vegetation was reaped in July 2009.The vegetation at the other was undisturbed for comparison.The comparisons indicate that the vegetation clearance has a major impact on ground temperatures in the active layer（shallower than 0.8 m in depth） in August,September and October.In summary,vegetation in forest area mainly cools the soils in warm season,but it serves as an insulator in cold season.More

关 键 词：大兴安岭林区 不同林型 多年冻土温度 冻结速率 

分 类 号：S718.5[农业科学—林学]