1958-2008年太白山太白红杉林碳循环模拟

太白红杉(Larix chinensis林主要分布于我国秦岭太白山的林线位置,对气候变化的响应十分敏感.为了定量分析太白山太白红杉林在气候变化背景下的碳循环特征,基于模型(MTCLIM)模拟的温度和降水数据,应用植被动态过程模型(LPJ-GUESS)模拟了太白山南北坡1958-2008年太白红杉林的净初级生产力(NPP)、生物量和净生态系统碳交换量(NEE).结果表明:1)太白红杉和巴山冷杉(Abies fargesii)的NPP和生物量在太白红杉林占有优势,太白红杉的NPP和生物量均大于巴山冷杉.1958-2008年间太白红杉南北坡NPP的平均值为0.38 kgC·m-2·a-1,巴山冷杉为0.25 kgC·m-2,a-1,两者之和占整个太白红杉林NPP的86％;1958-2008年间太白红杉南北坡生物量的平均值为2.91 kgC/m2,巴山冷杉为2.02 kgC/m2,两者之和占太白红杉林生物量的94％.2)太白红杉和巴山冷杉的NPP均表现为北坡大于南坡,且南北坡均有逐年增加的趋势,北坡的增幅小于南坡,所以太白山南北坡太白红杉林的NPP差异有逐年减少的趋势.3)太白红杉生物量的年际波动较大,南北坡呈交替上升趋势,南坡的平均值(2.94 kgC/m2)大于北坡(2.89 kgC/m2).巴山冷杉生物量的年际波动相对较小,北坡生物量水平大于南坡.4)1958-2008年南北坡太白红杉林平均NEE均为-0.023 kgC·m-2·a-1,表现为碳汇.南北坡碳汇水平均呈逐年增加趋势,南坡的增加幅度(0.91 g·m-2·a-1)大于北坡(0.42 g·m-2·a-1).以气候和CO2为驱动因子对太白山太白红杉林的长期碳循环动态做了定量分析,从机理上揭示气候变化与生态系统碳循环的关系,还需要做进一步的野外观测和控制实验研究.     

Modelling exploration of the future of European beech (Fagussylvatica L.) under climate change—Range,abundance, genetic diversity and adaptive response

We explored impacts of climate change on the geographic distribution of European beech by applying state of the art statistical and process-based models, and assessed possible climate change impacts on both adaptive capacity in the centre of its distribution and adaptive responses of functional traits at the leading and trailing edge of the current distribution. The species area models agree that beech has the potential to expand its northern edge and loose habitat at the southern edge of its distribution in a future climate. The change in local population size in the centre of the distribution of beech has a small effect on the genetic diversity of beech, which is projected to maintain its current population size or to increase in population size. Thus, an adaptive response of functional traits of small populations at the leading and trailing edges of the distribution is possible based on genetic diversity available in the local population, even within a period of 2–3 generations.     

Estimating Grazing Potentials in Sudan Using Daily Carbon Allocation in Dynamic Vegetation Model

Livestock production is important for local food security and as a source of income in sub-Saharan Africa. The human population of the region is expected to double by 2050, and at the same time climate change is predicted to negatively affect grazing resources vital to livestock. Therefore, it is essential to model the potential grazing output of sub-Saharan Africa in both present and future climatic conditions. Standard tools to simulate plant productivity are dynamic vegetation models (DVMs). However, as they typically allocate carbon to plant growth at an annual time step, they have a limited capability to simulate grazing. Here, we present a novel implementation of daily carbon allocation for grasses into the DVM Lund-Potsdam-Jena General Ecosystem Simulator (LPJ-GUESS) and apply this to study the grazing potential for the Kordofan region in Sudan. The results show a latitudinal split in grazing resources, where the northern parts of Kordofan are unexploited and southern parts are overused. Overall, we found that the modeled grazing potential of Kordofan is 16% higher than the livestock usage reported in the Food and Agricultural Organization of the United Nations, indicating a mitigation potential in the form of a spatial relocation of the herds.     

黄土高原潜在自然植被空间格局及其生境适宜性

植被生态系统的恢复越来越多地受到全球各界关注,潜在自然植被(potential natural vegetation, PNV)和生境适宜性概念应纳入植被规划,作为植被恢复的参考依据。基于高空间分辨率气候数据,使用动态植被模型(LPJ-GUESS),揭示黄土高原2001—2020年PNV空间格局及其生境适宜性的动态演变,并界定了植被优先恢复区。结果表明:黄土高原的PNV以草地和森林为主,潜在草地主要集中在北部、西北部地区(约占73.23%),潜在森林主要分布在南部地区(约占26.16%),极少的裸地主要分布在西部高海拔山区;在潜在森林中,温带落叶阔叶林、寒温性常绿针叶林、温带常绿针叶林占比分别为22.28%,3.88%,0.01%;随着气候变化的推进,潜在森林面积有所下降,而潜在草地面积有些许增加。PNV的生境适宜性呈现西北低、南部及东南高的分布,其中,分布在黄土高原南部平原地带的潜在温带落叶阔叶林其生境适宜性较高,而分布在北部及东北部的潜在草地其生境适宜性较低;并且,对于每种PNV类型,其最高生境适宜性所占据的地理空间及优先恢复区有较大差异。研究结果可为黄土高原植被恢复重建提供科学依据。     

2001-2100年黄土高原植被变化的土壤保持功能时空演变

基于LPJ-GUESS模型模拟分析2001—2100年黄土高原植被变化的土壤保持功能的时空演变及变化趋势,以期为该区制定适应气候变化的植被管理与侵蚀防治策略提供依据。结果表明:(1)2001—2100年黄土高原的土壤保持功能整体呈现"东南高、西北低"的分布特征。(2)2001—2020年黄土高原西部高海拔地区、东部五台山地区及西北部地区的土壤保持功能显著上升,SSP119情景下西部祁连山脉地区显著上升,中部少部分地区显著下降,SSP585情景下北部大部分地区显著上升。(3)2001—2020年黄土高原中部地区的土壤保持功能显著突变,SSP119情景下中南部及西部地区显著突变,SSP585情景下除南部以外的大部分地区显著突变。西部高海拔地区植被所带来的土壤保持功能下降,应该加强这部分地区的植被管理,比如科学种植适宜的植被。动态植被模型可以刻画气候变化下植被结构的动态变化,使土壤保持功能模拟得更精确,可采取类似LPJ-GUESS这样的动态植被模型在全球其他地区开展相应的研究。