东北森林带森林生态系统固碳服务空间特征及其影响因素

东北森林带作为国家主体生态区划"两屏三带"国家生态安全格局中的重要组成部分,在全球碳平衡中发挥着重要的碳汇作用。以东北森林带为研究区域,采用净生态系统生产力(NEP)评估其森林固碳服务,通过Anselin Local Moran's Ⅰ算法识别固碳服务的"热点"、"冷点"和"异常点",并分析探讨其空间格局与影响因素。结果表明:(1)东北森林带森林生态系统整体上是碳汇。2014年东北森林带森林固碳总量为36.41 Tg C/a,单位面积固碳量为89.57 g C m~(-2)a~(-1)。(2)固碳服务的热点区主要分布在大兴安岭北部和长白山中北部,冷点区主要分布在大兴安岭东部、小兴安岭和长白山南部,固碳服务的高值异常区域主要分布在森林边缘的农林交错带,低值异常区域主要分布在人为干扰严重的城市蔓延区。(3)东北森林带森林生态系统整体上受人为因素的影响小,其固碳服务与NDVI显著正相关。(4)城市扩张等人为干扰是固碳服务异常降低的根本原因,植被本身生长状况不佳和较高的温度是导致固碳服务的异常降低的重要影响因素。

Spatial and temporal patterns of carbon sequestration in the Northeastern Forest Regions and its impact factors analysis

The northeastern forest zone (NFZ) is a vital part of national strategic landscape of ecological security-Two Barriers and Three Belts of China, which has significant implications for carbon sink in global carbon balance. This study used net ecosystem production (NEP) as an indicator to evaluate carbon sequestration by forests in NFZ. Anselin Local Moran''I analysis was conducted to discern hotspots, coldspots, and outliers. The effects of natural and anthropogenic factors on carbon sequestration were explored by stepwise regression analysis and path analysis. Results indicated:(1) Overall, the forest ecosystem in NFZ acted as a carbon sink. The total amount of sequestrated carbon was 36.41 Tg C/a, with an average of 89.57 g C m^-2 a^-1. (2) Hotspots of NEP were mainly located in the northern part of the Daxing''an Mountains, the northern and central parts of the Changbai Mountains. Coldspots of NEP were mainly located in the eastern part of the Daxing''an Mountains, the Xiaoxing''an Mountains, and the southern part of the Changbai Mountains. Outliers of high NEP were mainly distributed in Agroforestry ecotones, while outliers of low NEP were mainly distributed in the areas of urban sprawl. (3) NEP of forest ecosystems in the northeastern forest zone positively correlated with NDVI; no significant relationships between anthropogenic factors and NEP were found. (4) Abnormally low values of NEP were primarily caused by anthropogenic factors (i.e., expansion of urban area). Simultaneously, a state of poor vegetation growth, as well as higher environmental temperature, could also prompt a decrease in carbon sequestration by forest patches.