冬季雪被对青藏高原东缘高海拔森林凋落叶P元素释放的影响  

Effect of snow cover on phosphorus release from leaf litter in the alpine forest in eastern Qinghai-Tibet plateau

作　　者：武启骞[1,2] 吴福忠[1] 杨万勤[1] 赵野逸[1] 何伟[1] 何敏[1] 朱剑霄[1,3] 

机构地区：[1]四川农业大学生态林业研究所,林业生态工程四川省重点实验室,成都611130 [2]东北林业大学生态研究中心,哈尔滨150040 [3]北京大学地表过程分析与模拟教育部重点实验室,北京100871

出　　处：《生态学报》2015年第12期4115-4127,共13页Acta Ecologica Sinica

基　　金：国家自然科学基金(31170423;31000213;31270498);国家"十二五"科技支撑计划(2011BAC09B05);四川省杰出青年学术与技术带头人培育项目(2012JQ0008;2012JQ0059);中国博士后科学基金特别资助(2012T50782)

摘　　要：雪被是影响高海拔森林凋落物分解的重要生态因子,其是否影响到生长季节与非生长季节凋落物中的P元素释放,尚未量化。为了量化季节性雪被对高海拔森林凋落物分解过程中P元素释放的影响,于2010年10月至2012年10月间,在青藏高原东缘川西高海拔森林不同厚度冬季雪被斑块下,设置凋落物分解袋实验。检测该地区代表性树种岷江冷杉(Abies faxoniana)、红桦(Betula albo-sinensis)、四川红杉(Larix mastersiana)和方枝柏(Sabina saltuaria)凋落叶在雪被覆盖不同关键时期(雪被形成前期、完全覆盖期和消融期)以及生长季节的P元素动态。结果表明,凋落物质量与雪被厚度均显著影响了P元素的释放过程。雪被覆盖时期凋落物P元素释放率表现为有雪被覆盖大于无雪被覆盖,而生长季节中除岷江冷杉外的其他3种凋落物P元素释放率均为无雪被覆盖下最大。相对于无雪被覆盖斑块,冬季雪被的存在提供了保护绝缘层,促进凋落物P元素释放,提高了各物种冬季P元素释放贡献率。这些结果表明,全球变化情景下的雪被减少可能减缓高海拔森林凋落物P元素的释放过程,改变森林土壤P元素水平。所以在研究高寒、高海拔地区全球气候变化下生态系统功能的工作中,应注重雪被这一异质性环境因子对生态系统功能的影响。Phosphorus （P） released from foliar litter plays crucial roles in maintaining soil fertility and ecosystem productivity in the P-limited forest ecosystem. The present consensus is that litter quality manipulates the rate of P release during decomposition at the local scale, and climate runs the global-scale patterns in N release during decomposition. Recently, increasing evidences have been demonstrated that the process of litter decomposition is greatly affected by winter snow cover in cold biomes. As yet, the response of foliar litter P dynamics to snow cover gradient created by forest gap and crown canopy in the high-altitude forest remains unknown. In order to understand the effect of snowpacks on winter foliar litter P dynamics and the following process in cold biomes, therefore, the litterbags with fir （Abies faxoniana）, birch （Betula albo-sinensis）, larch （Larix mastersiana） and cypress （Sabina saltuaria） foliar litters were placed on the forest floor beneath different snowpacks created by forest gap and crown canopy in three alpine forest plots of eastern Qinghai-Tibet Plateau on October 26, 2010. The litterbags were taken back at the periods of onset freezing, deeply freezing and thawing in the non-growing season and in the growing season from December 2010 to December 2012, and the mass loss and P concentration in foliar litters were measured. P concentrations in foliar litters under the snow cover gradient enriched at onset period of freezing, thereafter released at deeply freezing period, and then enriched at the thawing period regardless of tree species. 30.04% to 42.59% and 8.00% to 18.04% of P were released from foliar litters in the first- and second-year of decomposition, respectively, and varied with tree species and snowpack depth. 10.15% to 30.01%, and 2.28% to 16.54% of P in foliar litters were released in first and second winter, respectively. Snowpack created by forest gap accelerated the P release of foliar litter, and higher rate of P release from foliar litters was ob

关 键 词：青藏高原东缘 凋落叶 高海拔森林 磷释放 雪被梯度 

分 类 号：S714[农业科学—林学]