氮磷配施对藏北退化高寒草甸群落结构和生产力的影响  

Effects of nitrogen and phosphorous fertilization on community structure and productivity of degraded alpine meadows in northern Tibet,China

作　　者：宗宁[1,2] 石培礼 牛犇[1,2] 蒋婧[2,3] 宋明华 张宪洲 何永涛[1] 

机构地区：[1]中国科学院地理科学与资源研究所生态系统网络观测与模拟重点实验室拉萨高原生态试验站,北京100101 [2]中国科学院大学,北京100049 [3]中国科学院地理科学与资源研究所生态系统网络观测与模拟重点实验室,北京100101

出　　处：《应用生态学报》2014年第12期3457-3468,共12页Chinese Journal of Applied Ecology

基　　金：中国科学院战略性先导科技专项(XDA05060700);国家重点基础研究发展计划项目(2010CB833502)资助

摘　　要：施肥是退化草地初期恢复常用的管理措施,被用于改良草地群落结构和提高牧草生产力.本文以藏北轻度和重度退化高寒草甸为研究对象,设置低氮(50 kg N·hm-2·a-1,LN)、高氮(100 kg N·hm-2·a-1,HN)施肥水平,及其与磷配施组合试验(50 kg N·hm-2·a-1+50 kg P·hm-2·a-1,LN+P;100 kg N·hm-2·a-1+50 kg P·hm-2·a-1,HN+P),研究施肥梯度与施肥类型对两种退化程度高寒草甸群落结构、物种丰富度与多样性、群落生物量及其分配的影响.结果表明:单独施氮对轻度和重度退化高寒草甸群落盖度和生物量均无显著影响,而氮磷配施显著提高群落盖度及地上、地下生物量,其中LN+P处理的促进效果最显著.这表明本研究区地上生产力受到氮和磷的共同限制.施肥处理对重度退化样地总生物量无显著影响,但显著降低了根冠比.HN与HN+P处理均显著降低轻度退化群落的物种丰富度和均匀度,说明HN处理不利于轻度退化草地物种多样性和稳定性的维持.在轻度退化样地,施氮(尤其是HN处理)主要提高了禾草植物的重要值和生物量,而氮磷配施则有利于莎草类植物的生长.施肥对重度退化群落植物的重要值影响较小,主要提高了杂草生物量.说明轻度退化高寒草甸可选择低氮配施磷肥的措施,而对重度退化草地可能需要结合围栏和补播牧草等其他管理措施进行改良.Fertilization is an effective management measure for recovery oi degraded grasslands. To better understand the effects of fertilization on community structure and productivity of lightly and severely degraded alpine meadows, we conducted a fertilization experiment in northern Tibet since 2008. The treatments were addition of nitrogen （N） alone （50 kg N ·hm-2 · a-1, LN; 100 kgN·hm-2 ·a-1, HN） or addition of both phosphorus （P） and N （50 kg N ·hm-2 · a-1＋50 kg P · hm-2 · a-1, LN＋P; 100 kg N · hm-2 · a-1＋50 kg P · hm-2· a-1 , HN＋P） in each of the two types of degraded alpine meadows. N addition alone significantly affected plant community co- verage or productivity in neither the slightly nor the severely degraded alpine meadow, while addi- tion of both N and P significantly increased plant community coverage, aboveground and below- ground biomass of the alpine meadows. This suggested that productivity of this alpine meadow is co-limited by N and P. HN and HN＋P significantly decreased species richness and evenness in the lightly degraded grassland, indicating that HN was not beneficial for the lightly degraded grassland to maintain species diversity and community stability. N addition significantly reduced the root to shoot ratio in the severely degraded meadow. In the lightly degraded meadow, N addition alone, es- pecially with a high amount （ HN）, enhanced the importance values （IV） and biomass of grasses, while fertilization with both N and P increased those of sedges. In the severely degraded meadow, fertilization had litde effect on IV of grasses or sedges, but improved biomass of forbs. The results suggested that LN＋P could be employed in recovery of lightly degraded alpine meadows, but other management measures such as fencing and reseeding may be needed for recovery of severely degrad- ed alpine meadows.

关 键 词：氮磷添加 植被恢复 草地改良 退化高寒草甸 西藏高原 

分 类 号：S812[农业科学—草业科学]