Background:Recent warming is affecting species composition and species areal distribution of many regions.However,although most treeline studies have estimated the rates of forest expansion into tundra,still little is...Background:Recent warming is affecting species composition and species areal distribution of many regions.However,although most treeline studies have estimated the rates of forest expansion into tundra,still little is known about the long-term dynamic of stand productivity at the forest-tundra intersection.Here,we make use of tree-ring data from 350 larch(Larix sibirica Ledeb.)and spruce(Picea obovata Ledeb.)sampled along the singular altitudinal treeline ecotone at the Polar Urals to assess the dynamic of stand establishment and productivity,and link the results with meteorological observations to identify the main environmental drivers.Results:The analysis of stand instalment indicated that more than 90%of the living trees appeared after 1900.During this period,the stand became denser and moved 50m upward,while in recent decades the trees of both species grew faster.The maximum afforestation occurred in the last decades of the twentieth century,and the large number of encountered saplings indicates that the forest is still expanding.The upward shift coincided with a slight increase of May-August and nearly doubling of September-April precipitation while the increase in growth matched with an early growth season warming(June+0.27°C per decade since 1901).This increase in radial growth combined with the stand densification led to a 6-90 times increase of biomass since 1950.Conclusion:Tree-ring based twentieth century reconstruction at the treeline ecotone shows an ongoing forest densification and expansion accompanied by an increased growth.These changes are driven by climate change mechanism,whereby the leading factors are the significant increase in May-June temperatures and precipitation during the dormant period.Exploring of phytomass accumulation mechanisms within treeline ecotone is valuable for improving our understanding of carbon dynamics and the overall climate balance in current treeline ecosystems and for predicting how these will be altered by global change.展开更多
Aims This study aimed to develop radial growth models and to predict the potential spatial distribution of Pinus densiflora(Japanese red pine)and Quercus spp.(Oaks)in South Korea,considering topographic and climatic f...Aims This study aimed to develop radial growth models and to predict the potential spatial distribution of Pinus densiflora(Japanese red pine)and Quercus spp.(Oaks)in South Korea,considering topographic and climatic factors.Methods We used a dataset of diameter at breast height and radial growth estimates of individual trees,topographic and climatic factors in systematic sample plots distributed over the whole of South Korea.On the basis that radial growth is attributed primarily to tree age,we developed a radial growth model employing tree age as an explanatory variable.We estimated standard growth(SG),defined as radial growth of the tree at age 30,to eliminate the influence of tree age on radial growth.In addition,SG estimates including the Topographic Wetness Index,temperature and precipitation were calculated by the Generalized Additive Model.Important Findings As a result of variogram analysis of SG,we found spatial autocorrelation between SG,topographic and climatic factors.Incremental temperature had negative impacts on radial growth of P.densiflora and positive impacts on that of Quercus spp.Precipitation was associated with positive effects on both tree species.Based on the model,we found that radial growth of P.densiflora would be more vulnerable than that of Quercus spp.to climatic factors.Through simulation with the radial growth model,it was predicted that P.densiflora stands would be gradually replaced with Quercus spp.stands in eastern coastal and southern regions of South Korea in the future.The models developed in this study will be helpful for understanding the impact of climatic factors on tree growth and for predicting changes in distribution of P.densiflora and Quercus spp.due to climate change in South Korea.展开更多
In the context of climate change, planning for forest management goals becomes more complicated. Possible changes in precipitation, temperature, and CO2 can affect tree growth substantially and potential effects diffe...In the context of climate change, planning for forest management goals becomes more complicated. Possible changes in precipitation, temperature, and CO2 can affect tree growth substantially and potential effects differ by species and region. However, integration of potential forest growth responses to these factors can be achieved using models. Because of the need to understand the range of forest growth forecasts and the strengths and limitations of different modeling approaches, I summarized results from 25 studies of forecasted forest responses over coming decades. Some models used statistical relationships between tree rings and climate to forecast growth responses to future climate, some simulated net photosynthesis of a standard forest canopy, and many used tree or stand growth models at various levels of mechanistic detail. In general, models that included CO2 responses predicted enhanced forest growth by 2100 across most of the commercial timberland areas of the US and Canada. For modest warming, most models showed growth enhancement in most regions. For hotter scenarios, many models and regions showed even more growth enhancement, but some regions such as the Southwest, mountain West, and southwestern Canada were predicted to experience drought stress and increased fire incidence, although projections in these regions were variable. Young stands, angiosperms, and early-successional species were predicted to exhibit the most positive responses. As a result, commercial harvest ages might be accelerated by several years, depending on species. Some simulations for the Midwest and Northeast US predicted a doubling or more of net primary productivity although other studies show a lesser response. Model runs that did not include mechanisms of CO2 fertilization showed positive growth responses in only limited cases and generally showed growth declines. There also was some evidence indicating the potential spread of forest into woodland at shrub or prairie ecotones.展开更多
基金N.D.,V.K.,A.G.,and A.G.were supported by the Russian Science Foundation(Grant No.17-14-01112)V.M.was supported by the Russian Foundation of Basic Research(Grant No.19-05-00756)Data collection was partly performed within the frameworks of a state contract with the Institute of Plant and Animal Ecology,Ural Branch,Russian Academy of Sciences.
文摘Background:Recent warming is affecting species composition and species areal distribution of many regions.However,although most treeline studies have estimated the rates of forest expansion into tundra,still little is known about the long-term dynamic of stand productivity at the forest-tundra intersection.Here,we make use of tree-ring data from 350 larch(Larix sibirica Ledeb.)and spruce(Picea obovata Ledeb.)sampled along the singular altitudinal treeline ecotone at the Polar Urals to assess the dynamic of stand establishment and productivity,and link the results with meteorological observations to identify the main environmental drivers.Results:The analysis of stand instalment indicated that more than 90%of the living trees appeared after 1900.During this period,the stand became denser and moved 50m upward,while in recent decades the trees of both species grew faster.The maximum afforestation occurred in the last decades of the twentieth century,and the large number of encountered saplings indicates that the forest is still expanding.The upward shift coincided with a slight increase of May-August and nearly doubling of September-April precipitation while the increase in growth matched with an early growth season warming(June+0.27°C per decade since 1901).This increase in radial growth combined with the stand densification led to a 6-90 times increase of biomass since 1950.Conclusion:Tree-ring based twentieth century reconstruction at the treeline ecotone shows an ongoing forest densification and expansion accompanied by an increased growth.These changes are driven by climate change mechanism,whereby the leading factors are the significant increase in May-June temperatures and precipitation during the dormant period.Exploring of phytomass accumulation mechanisms within treeline ecotone is valuable for improving our understanding of carbon dynamics and the overall climate balance in current treeline ecosystems and for predicting how these will be altered by global change.
基金Korea Forest Service research project‘Growth response model for major tree species using tree-ring information of national forest inventory(Project No:S120911L030130)’‘A3 Foresight Program(A307-K005)’provided by National Research Foundation of Korea.
文摘Aims This study aimed to develop radial growth models and to predict the potential spatial distribution of Pinus densiflora(Japanese red pine)and Quercus spp.(Oaks)in South Korea,considering topographic and climatic factors.Methods We used a dataset of diameter at breast height and radial growth estimates of individual trees,topographic and climatic factors in systematic sample plots distributed over the whole of South Korea.On the basis that radial growth is attributed primarily to tree age,we developed a radial growth model employing tree age as an explanatory variable.We estimated standard growth(SG),defined as radial growth of the tree at age 30,to eliminate the influence of tree age on radial growth.In addition,SG estimates including the Topographic Wetness Index,temperature and precipitation were calculated by the Generalized Additive Model.Important Findings As a result of variogram analysis of SG,we found spatial autocorrelation between SG,topographic and climatic factors.Incremental temperature had negative impacts on radial growth of P.densiflora and positive impacts on that of Quercus spp.Precipitation was associated with positive effects on both tree species.Based on the model,we found that radial growth of P.densiflora would be more vulnerable than that of Quercus spp.to climatic factors.Through simulation with the radial growth model,it was predicted that P.densiflora stands would be gradually replaced with Quercus spp.stands in eastern coastal and southern regions of South Korea in the future.The models developed in this study will be helpful for understanding the impact of climatic factors on tree growth and for predicting changes in distribution of P.densiflora and Quercus spp.due to climate change in South Korea.
文摘In the context of climate change, planning for forest management goals becomes more complicated. Possible changes in precipitation, temperature, and CO2 can affect tree growth substantially and potential effects differ by species and region. However, integration of potential forest growth responses to these factors can be achieved using models. Because of the need to understand the range of forest growth forecasts and the strengths and limitations of different modeling approaches, I summarized results from 25 studies of forecasted forest responses over coming decades. Some models used statistical relationships between tree rings and climate to forecast growth responses to future climate, some simulated net photosynthesis of a standard forest canopy, and many used tree or stand growth models at various levels of mechanistic detail. In general, models that included CO2 responses predicted enhanced forest growth by 2100 across most of the commercial timberland areas of the US and Canada. For modest warming, most models showed growth enhancement in most regions. For hotter scenarios, many models and regions showed even more growth enhancement, but some regions such as the Southwest, mountain West, and southwestern Canada were predicted to experience drought stress and increased fire incidence, although projections in these regions were variable. Young stands, angiosperms, and early-successional species were predicted to exhibit the most positive responses. As a result, commercial harvest ages might be accelerated by several years, depending on species. Some simulations for the Midwest and Northeast US predicted a doubling or more of net primary productivity although other studies show a lesser response. Model runs that did not include mechanisms of CO2 fertilization showed positive growth responses in only limited cases and generally showed growth declines. There also was some evidence indicating the potential spread of forest into woodland at shrub or prairie ecotones.
文摘杉木(Cunninghamia lanceolata)是亚热带地区主要造林树种之一,其在区域碳循环和缓解气候变化中起着重要的作用。以亚热带地区6个站点(荆关、马鬃岭、分宜、将乐、东风、高峰)杉木人工林为研究对象,建立树轮标准化年表,分析树木年轮年表与气候因子的关系,解析不同研究区杉木径向生长对气候变化的响应机制,探讨不同站点杉木对干旱事件的响应策略,为该地区杉木人工林的经营管理提供理论依据。研究结果表明,6个研究区杉木树轮宽度对气候变化的平均敏感度大于0.15,样本总体代表性大于0.85,均处于可接受水平,表明6个站点的杉木样本具有区域代表性,适用于进行气候相关分析。杉木径向生长主要与生长季的平均温度和降水量、上一年夏季的最低温度正相关,与当年夏季最高温度负相关,高峰站点的径向生长与7-10月的相对湿度显著正相关,其他地点径向生长与月相对湿度相关性较弱,分宜、东风和高峰站的径向生长与干旱指数显著正相关,其他地点的杉木树轮宽度与干旱指数相关性较弱。干旱事件对6个站点杉木生长均产生了负面影响,胸高断面积增长(Basal area increment, BAI)呈先上升后下降的趋势,在生长后期,6个研究点的BAI出现不同程度的衰退现象。第二次干旱发生后,杉木对干旱事件的应对能力更强。亚热带纬度较低的地区杉木受到干旱的影响较大,温暖而湿润环境下的杉木对干旱事件的抵抗力较小,恢复力较高。
