土地利用和气候变化对森林地上生物量的影响模拟——以江西省泰和县为例

以土地利用变化和气候变化为特征的全球和区域环境变化及其影响已经成为国际社会和公众关注的焦点,同时也是土地科学、全球变化科学和全球生态学关注的关键问题。由于土地、气候和森林生态系统之间存在着复杂而密切的关系,土地利用变化和气候变化将不可避免地对森林结构和功能产生重要影响。如何采用合理的适应措施降低这些变化可能带来的损失,是目前全球变化研究亟待解决的问题之一。因此,研究土地利用和气候变化对森林的单独及综合影响具有重要的科学意义。本文综合利用基于主体的土地利用模型（ABM/LUCC）、生态系统过程模型（PnET-II）以及森林景观动态模型（LANDIS-II）构建了综合模拟研究框架,选择森林类型多样且具有长期观测数据积累的江西省泰和县为研究区,模拟并对比了土地利用和气候变化组合情景下未来森林地上总生物量的变化差异。结果表明：① 土地利用变化对泰和县森林地上总生物量的影响比气候变化所带来的影响更加显著。研究区森林地上总生物量在有土地利用变化干扰的情景下与RCP 2.6、RCP 4.5和RCP 8.5单独的气候情景下相比分别减少33.13%、32.92%和32.42%;② 尽管未来气候变化可能有利于森林地上总生物量的积累,但土地利用变化将使森林地上总生物量显著减少,并将抵消气候变化带来的正效应;③ 本文提出的综合模拟研究框架可以很好地模拟土地利用和气候变化对森林生态系统的影响,可为提升和优化人工林结构和功能、开展可持续森林管理提供科学建议。     

气候变化和人类活动对南方红壤丘陵区森林生态系统影响模拟研究——以江西泰和县为例

在全球气候变化和人类活动的影响下,森林生态系统结构、功能以及空间格局都将发生不同程度的变化。明晰景观尺度上未来森林的动态变化,对森林可持续发展具有重要意义。选择江西省泰和县为研究区,综合利用土地利用模型（CA-Markov）和森林景观动态模型（LANDIS-II）,并结合生态系统过程模型（PnET-II）,模拟气候变化、土地利用、采伐以及综合情景下未来40年（2010-2050年）阔叶林、针叶林的面积及生物量变化。结果表明：① 气候变化对森林面积影响较小,采伐使森林面积显著减少,土地利用变化使森林面积的变化更加剧烈;② 针叶林和阔叶林对不同干扰方式的响应表现出较强差异,针叶林对采伐的响应更加剧烈;③ 多模型综合模拟方法有助于区域森林管理,为南方红壤丘陵区森林结构优化和功能提升提供科学建议。     

Social and biophysical determinants of future forest conditions in New England: Effects of a modern land-use regime

The future forests of eastern North America will be shaped by at least three broad drivers: (i) vegetation change and natural disturbance patterns associated with the protracted recovery following colonial era land use, (ii) a changing climate, and (iii) a land-use regime that consists of geographically variable rates and intensities of forest harvesting, clearing for development, and land protection. We evaluated the aggregate and relative importance of these factors for the future forests of New England, USA by simulating a continuation of the recent trends in these drivers for fifty-years, nominally spanning 2010 to 2060. The models explicitly incorporate the modern distribution of tree species and the geographical variation in climate and land-use change. Using a cellular land-cover change model in combination with a physiologically-based forest landscape model, we conducted a factorial simulation experiment to assess changes in aboveground carbon (AGC) and forest composition. In the control scenario that simulates a hypothetical absence of any future land use or future climate change, the simulated landscape experienced large increases in average AGC—an increase of 53% from 2010 to 2060 (from 4.2 to 6.3 kg m⁻²). By 2060, climate change increased AGC stores by 8% relative to the control while the land-use regime reduced AGC by 16%. Among land uses, timber harvesting had a larger effect on AGC storage and changes in tree composition than did forest conversion to non-forest uses, with the most pronounced impacts observed on private corporate-owned land in northern New England. Our results demonstrate a large difference between the landscape’s potential to store carbon and the landscape’s current trajectory, assuming a continuation of the modern land-use regime. They also reveal aspects of the land-use regime that will have a disproportionate impact on the ability of the landscape to store carbon in the future, such as harvest regimes on corporate-owned lands. This information will help policy-makers and land managers evaluate trade-offs between commodity production and mitigating climate change through forest carbon storage.