基于NPP数据和样区对比法的青藏高原自然保护区保护成效分析

在青藏高原选择11个代表性自然保护区,基于高寒草地植被净初级生产力（Net Primary Production,简写NPP）变化过程数据,比较分析了自然保护区与其相邻等面积区域的NPP变化差异;采用样区对比法,在自然保护区内外选取21组对比样区,比较自然保护区建立前后及其内外的生态状况,评估了自然保护区的保护成效。研究表明：1. 1982-2009年间,82%的代表性自然保护区NPP比保护区周邻区域及青藏高原的平均水平低,反映了自然保护区的生态系统状况更为脆弱;2. 在代表性自然保护区中,曼则塘自然保护区的NPP增长趋势最为明显,塔什库尔干野生动物自然保护区的NPP增长趋势最弱;除色林错自然保护区外,以草甸和湿地为主的自然保护区NPP增速明显高于以草原与荒漠草地为主的自然保护区;3. 代表性样区的研究发现：① 自然保护区内76%以上的样区和国家级保护区内82%以上的样区NPP增加幅度明显高于保护区外对应样区的增幅;② 取得明显保护效果的有中昆仑、长沙贡玛、若尔盖和色林错等自然保护区;曼则塘自然保护区的东南部边缘地区和塔什库尔干野生动物自然保护区的北部边缘地区的效果不明显,可能与保护区及其周邻地区人类扰动增强密切相关;③ 高寒草甸类型自然保护区的保护效果最为显著,高寒草原类型自然保护区的保护效果较差。本研究展示了样区对比法在评估大区域生态变化中所具有的独特优势,其关键在于科学设计样区并进行合理的空间抽样。

Assessment of protection effectiveness of nature reserves on the Tibetan Plateau based on net primary production and the large-sample-comparison method

A total of 21 typical coupled large samples were chosen from areas in the nature reserves and their surroundings on the Tibetan Plateau (TP) with large-sample-comparison method (LSCM). To evaluate the protection effectiveness of the nature reserves, we compared the alpine grassland net primary production (NPP) of these coupled samples and analyzed the differences between them before and after their establishment as protected areas. The results show that: (1) In view of alpine grassland NPP, the ecological and environmental conditions of most nature reserves were more fragile than those of their surrounding areas and also lower than the average values for the TP. (2) Of the 11 typical nature reserves selected, the positive trend of NPP in Manzetang is the most significant, while in Taxkorgan, the trend is not obvious. Moreover, with the exception of Selincuo, the annual NPP growth rate in nature reserves covered by meadow and herbaceous wetland is higher than that in nature reserves consisting of steppe and desert grassland. (3) Some notable findings existed in 21 typical coupled samples: (a) After the establishment of nature reserves, the annual NPP increase rate in 76% of samples inside nature reserves and 82% of samples inside national nature reserves are apparently higher than that of corresponding samples outside nature reserves. (b) The ecological protection effectiveness in Central Kunlun, Changshagongma, Zoige Wetland, and Siling Co nature reserves is significant; in most parts of the Three Rivers' Source and Qiangtang nature reserves, the protection effectiveness is relatively significant, while in south-east Manzetang and north Taxkorgan, the protection effectiveness is not obvious. (c) The ecological protection effectiveness is significant in nature reserves consisting of meadow; however, it is weak in nature reserves covered by steppe.