黑龙江省20世纪森林变化及对氧气释放量的影响

张丽娟 Zhang Lijuan,姜春艳 Jiang Chunyan,吴霜 Wu Shuang,马骏 Ma Jun,姜蓝齐 Jiang Lanqi,张安康 Zhang Ankang

doi:10.5846/stxb201304280861

Abstract

随着对大气环境质量研究的深入，大气中氧气含量变化也引起了关注。森林是固碳释氧的重要生态系统，黑龙江省近百年来，森林面积减少了37.163%，估算由此导致的森林氧气释放量变化，对研究大气氧气含量变化具有重要意义。以黑龙江省1900年、1949年、1986年和2009年为时间断面，采用C-FIX模型及碳氧平衡方法，模拟并分析了20世纪黑龙江省森林氧气释放量及其变化。结果表明：（1）黑龙江省20世纪森林面积减少了106667.570 km2，森林覆盖率减少了23.568%。除樟子松（Pinus sylvestris var. mongolica）林、针阔混交林面积有所增加外，其它树种的森林面积均减少，其中云冷杉（Picea asperata and Abies nephrolepis）林及红松（Pinus koraiensis）林面积减少超过80%，空间上以松嫩平原及三江平原减少最为显著；（2）森林年氧气释放量百年来减少了5621.560万t，减少近三分之一，其空间变化明显，西南部森林氧气释放量由百年前的最高区域变为最低区域，三江平原释放氧气的森林区域明显减少；（3）百年来各行政区森林年氧气释放量除伊春微弱增加外，其余均呈减少趋势。其中大庆市、齐齐哈尔市减少显著，减少了90%以上；（4）控制实验表明，森林面积变化导致黑龙江省区域森林年氧气释放量减少了50%。人类活动引起的森林面积减少，是导致黑龙江省森林氧气释放量减少的主要因素。;Through recent extensive studies on air quality, researchers have paid more attention to changes in oxygen content in the atmosphere. Studies show atmospheric oxygen in the lower atmosphere has a slow diminishing trend. The forest ecosystem is an important source of carbon sequestration and oxygen release, so, oxygen content is directly impacted by the change of forest area. Therefore, it is essential to examine the deforestation process and evaluate its impact on the changes of oxygen content in the atmosphere. Heilongjiang Province is the area in China primarily focused on forest resources and coverage, however, during the past century approximately 37.163% of the forest area has been converted to other land uses. We selected Heilongjiang Province as the research area, as it provided greater significance to study the variation of oxygen content in the atmosphere due to the estimated change of oxygen release caused by deforestation. According to historical references and remote sensing image data, we rebuilt the forest spatial distribution of Heilongjiang Province in 1900, 1949, 1986 and 2009. Using the C-FIX Model and carbon-oxygen balance method, this research simulated and analyzed the quantity and changes of oxygen released by the forest ecosystemof Heilongjiang Province.Analyses of the results suggest four major conclusions. First, the forest area of Heilongjiang has decreased by 106667.570 km2, or approximately 23.568% during the last century (1900-2009). Except for Pinussylvestris var. mongolica forest and Coniferous and broad leaved mixed forest, the geographic areas of all other forest types have decreased, within which the areas of Piceaasperata and Abiesnephrolepis forest and Pinuskoraiensis forest have decreased by more than 80%.Spatially, significant forest loss can be found in the Songnen and Sanjiang Plains. Second, during the last century, the quantity of oxygen released has been reduced by 56.2156 million tons, or approximately one-third of that in 1900. The oxygen production in the Southwest was the highest in 1900, but became the area with the lowest production in 2009. Moreover, a significant decrease of forest oxygen production occurred in the Sanjiang Plain. Third, the quantity of oxygen released from almost all administrative regions of Heilongjiang presents a decreasing trend, with the exception of Yichun. Among these regions, the quantity of oxygen released has reduced more than 90% in Daqing City and Qiqihar City; over 50% in Jiamusi City, Suihua City, and Jixi City; over 25% in Shuangyashan City, Qitaihe City and Heihe City; less than 10% in Daxinganling Region and Mudanjiang City. Fourth, during the past century,the total amount of oxygen released by Picea asperataand Abies nephrolepis forest has reduced by 91.855%, 78.905% by Pinuskoraiensis forest, and by 25.043% and 23.936% by deciduous mixed forest and Larixgmelini forest, respectively. However, the total amounts of oxygen released by Coniferous and broad leaved mixed forest and Pinus sylvestris var. mongolica forest increased by 20.356% and 48.209%,respectively. Piceaasperataand Pinus koraiensis forest released the most amount of oxygen per unit area; Larixgmelini forest and Pinus sylvestris var. mongolica forest released less. Finally, the results of the control experiments suggest that forest oxygen production in Heilongjiang is only approximately half of the amount in 1900.Moreover, forest degradationdue to human activities is one of the major factors that leads to the decrease of the quantity of oxygen released.

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