基于NbS的北京市乔木林固碳能力分析

【目的】乔木林生物质碳汇是影响森林碳汇的重要组成部分,是一种自然的气候解决方案,在全球气候变化大背景下,森林的固碳潜力一直被广泛关注,本文以北京市为例,分析不同的林业活动对乔木碳储量的影响。【方法】采用北京市森林资源设计调查数据,利用IPCC材积源-生物量法估算北京市乔木林碳储量,分析了2009-2014年北京市在森林转化、造林以及森林经营3种自然方案下碳储量的变化情况。【结果】(1)2009-2014年北京市森林面积净增长8.35×10^(4)hm^(2),碳储量净增量约1.45×10^(9)kg,年均碳固持量为0.29×10^(9)kg/a。(2)2014年北京市人工林总碳储量高于天然林,且碳密度高于天然林。当前北京市森林龄级结构偏低龄化,随着森林的自然生长,仍有较大的碳固持潜力。在各个优势树种(组)中,人工杨树林的固碳效率尤为突出,远远高于其他优势树种。(3)山地森林活动强度较小,森林经营区域占比较大,城市森林变化剧烈,受造林与森林转化等措施影响较大。2009-2014年北京市由于森林转化为其他土地造成了1.06×10^(9)kg的碳损失,造林带来了2.10×10^(9)kg的碳固持,森林经营过程中有1.62×10^(9)kg的碳固持与1.21×10^(9)kg的碳损失,森林经营活动的总碳储量净增量0.41×10^(9)kg,避免森林转化可以带来1.17×10^(9)kg的碳汇。【结论】增加乔木林的固碳能力是应对气候变化的重要手段,避免森林转化可以凭借较小的森林面积贡献较大的碳汇,是一种低成本且效果显著的增汇方案。

Characteristic Change of Several Forest Landscapes Between 1896 and 1986 in Heilongjiang Province

Five forest landscapes in the maps of forest distribution in Heilongjiang Province in 1896 and 1986 were digitized and analyzed through GIS software. The results show that during the 90 years the total patch areas for Picea and Abies forest, Pinus sylvestris var. mongolica Litvin forest and Pinus koraiensis Sieb. et Zucc. forest had decreased about 87%, 40% and 84%, respectively. However, the total patch areas for broad leaved forest at the north of 51°N area had increased about 500%. The north frontier of broad leaved forest had moved towards northwest about 290 km. The fractal dimensions of Picea and Abies forest and mixed coniferous and broad leaved forest in 1986 were less than theirs in 1896, respectively. However, the fractal dimension of Pinus synvestris forest, Pinus koraiensis and broad leaved forest were more than theirs in 1896, respectively. Picea and Abies forest, Pinus synvestris forest, Pinus koraiensis and broad leaved forest became more fragmented. The transition percentages of Pinus sylvestris forest, Picea and Abies forest, Pinus koraiensis forest to themselves were less than the percentages to the mixed coniferous and broad leaved forest, respectively.

川西亚高山3种森林土壤碳氮磷及微生物生物量特征

以空间代替时间的方法,对川西亚高山天然针叶林、桦木次生林、人工云杉林有机层和矿质层土壤碳、氮、磷化学计量以及土壤微生物生物量和呼吸进行比较分析.结果表明,天然针叶林转化为次生林和人工林,土壤有机层碳、氮、磷,微生物生物量碳、氮含量及微生物呼吸均显著下降,其中微生物生物量碳依次为天然林(727.98 mg/kg)>次生林(554.56 mg/kg)>人工林(239.83 mg/kg),微生物生物量氮为天然林(72.56 mg/kg)>次生林(50.42 mg/kg)>人工林(20.78 mg/kg),而矿质层各测定变量在3个森林群落之间差异基本不显著.各森林群落有机层土壤碳、氮、磷,微生物生物量及呼吸均显著高于矿质层,而碳氮比和微生物生物量碳氮比在土壤层次之间差异不大.相关分析表明,土壤碳、氮、磷及化学计量比及微生物变量之间存在显著相关关系.综上所述,森林转换显著影响川西亚高山土壤碳、氮、磷化学计量及微生物生物量,且影响主要体现在土壤有机层.