松嫩平原西部草地净初级生产力对气候变化及人类活动的响应

Responses of grassland net primary productivity in western Songnen Plain of Northeast China to climate change and human activity

利用相关分析及缓冲区分析方法,选取气温、降水两个主要气候要素及道路、居民地两类人类主要活动区,以分析气象因素及人类活动对2000—2009年松嫩西部草地NPP的影响。结果表明:过去10年间,松嫩平原西部草地平均气温为5.39℃,受纬度影响由北向南递增;年均降水量为378mm,空间上呈由西南向东北递减的分布格局。气温升高、降水量增加能够促进松嫩西部草地NPP的升高,且降水对松嫩西部草地NPP的影响强于气温,这与松嫩西部草地盐碱化、沙漠化的干燥、缺水的气候条件相符合。年尺度NPP的统计结果均不显著,而月尺度则全部表现为极显著(P<0.01),说明统计结果的显著性受时间尺度影响较大。人文影响因素分析发现,道路和居民地与草地NPP的关系完全相反,距离道路越近,呈好转趋势的草地面积越大,越远受人类活动影响越明显,主要与研究区人为管理的实施及居民生产、生活方式有关;离居民地距离越远,人类活动的强度或影响草地的能力越低,草地长势越好。居民地对草地NPP变化的影响明显强于道路,主要原因是:一方面松嫩西部居民地的密度远大于道路;另一方面,自2000年以来研究区人口数量增加导致的居民地修建及维持生计的开荒和放牧。

By the methods of correlation analysis and buffer analysis, and taking two main climate factors （air temperature and precipitation） and two main human activity areas （road and residential land） into account, this paper studied the effects of climate change and human activity on grassland net primary productivity （NPP） in western Songnen Plain in 2000-2009. In the past ten years, the mean air temperature in the study area was 5.39 ~C, which increased from north to south, and the mean precipitation was 378 mm, which decreased from northeast to south- west. The grassland NPP increased with the increase of air temperature and precipitation. Com- pared with air temperature, precipitation affected NPP more obviously, which accorded with the special climate conditions of water shortage in western Songnen Plain. The difference in the NPP was not significant at yearly scale but extremely significant at monthly scale, indicating that time scale had remarkable effects on the statistical significance. The effects of road and residential land on the NPP were completely opposite. The closer to the road, the larger area the grassland with good plant growth, which could related to the appropriate management measures and the ways of local human activities; while the further to the residential land, the weaker the human activities intensity or their capabilities in affecting the grassland, the better the plant growth on the grassland. Compared with road, residential land had more obvious effects on the grassland NPP, possibly due to the higher density of residential land and the more frequent building con- struction, reclamation, and grazing caused by population increase.