Background:Understanding the spatial pattern and driving factors of forest carbon density in mountainous terrain is of great importance for monitoring forest carbon in support of sustainable forest management for miti...Background:Understanding the spatial pattern and driving factors of forest carbon density in mountainous terrain is of great importance for monitoring forest carbon in support of sustainable forest management for mitigating climate change.Methods:We collected the forest inventory data in 2015 in Shanxi Province,eastern Loess Plateau of China,to explore the spatial pattern and driving factors of biomass carbon density(BCD)for natural and planted coniferous forests using Anselin Local Moran’s I,Local Getis-Ord G*and semivariogram analyses,and multi-group structural equation modeling,respectively.Results:The result of spatial pattern of BCDs for natural forests showed that the BCD was generally higher in the north but lower in the south of Shanxi.The spatial pattern for planted forests was substantially different from that for natural forests.The results of multi-group SEM suggested that elevation(or temperature as the alternative factor of elevation)and stand age were important driving factors of BCD for these two forest types.Compared with other factors,the effects of latitude and elevation on BCD showed much greater difference between these two forest types.The difference in indirect effect of latitude(mainly through affecting elevation and stand age)between natural and planted forests was to some extent a reflection of the difference between the spatial patterns of BCDs for natural and planted forests in Shanxi.Conclusions:The natural coniferous forests had a higher biomass carbon density,a stronger spatial dependency of biomass carbon density relative to planted coniferous forests in Shanxi.Elevation was the most important driving factor,and the effect on biomass carbon density was stronger for natural than planted coniferous forests.Besides,latitude presented only indirect effect on it for the two forest types.展开更多
Aims Large hurricanes have profound impacts on temperate forests,but owing to their infrequent nature these effects have rarely been examined in detail.In 1996,Hurricane Fran significantly damaged many long-term tree ...Aims Large hurricanes have profound impacts on temperate forests,but owing to their infrequent nature these effects have rarely been examined in detail.In 1996,Hurricane Fran significantly damaged many long-term tree census plots in the Duke Forest on the North Carolina Piedmont,thereby providing an exceptional opportunity to examine pre-and post-hurricane forest compositional trajectories.Our goal was to examine immediate,short-term(0–4 years)and longer term(;5 year)hurricane-induced structural,spatial and compositional changes in the tree population(stem d.b.h>1 cm)in the context of our detailed,long-term knowledge of the dynamics of these forests.Methods We surveyed stem damage and tree mortality in 34 long-term permanent plots(ca.70-year record;404–1012 m^(2))and 7 large mapped tree stands(ca.20-year record;5250–65000 m^(2))representing both transition-phase,even-aged pine stands and uneven-aged upland hardwood forests.We employed three types of damage measures to quantify stand-level damage severity:percentage of stems damaged,percentage of basal area lost and a‘stand-level damage index’.Second-order spatial analysis(Ripley’s K-function)was used to investigate patterns in tree mortality.Important findings Our study found hurricane effects on the structural attributes of Piedmont forests to be variable and patchy.Changes in tree species composition,however,were modest.Uprooting was the major damage type for the overstory trees[diameter at breast height(d.b.h.)>10 cm]apparently due to the exposure of the crowns to high wind combined with heavy rainfall prior to and during the storm.Saplings,juvenile trees and small trees(1–10 cm d.b.h.)of the understory and midstory were mainly damaged by being pinned or bent by their damaged large neighbors.Hurricane-induced tree mortality varied weakly among species,was positively correlated with pre-hurricane tree size and remained up to 2-fold higher than pre-hurricane background mortality 5 years after the hurricane.Spatial point pattern analysis revealed a patchy distribution of tree mortality during the hurricane sampling interval.Hurricane Fran resulted in a dramatic increase in average gap size from ca.400 m^(2) pre-hurricane to ca 1100 m^(2) after the hurricane,whereas maximum gap sizes reached 18–34 times larger than the pre-hurricane levels.展开更多
Climate warming is expected to advance treelines to higher elevations. However, empirical studies in diverse mountain ranges give evidence of both advancing alpine treelines as well as rather insignificant responses. ...Climate warming is expected to advance treelines to higher elevations. However, empirical studies in diverse mountain ranges give evidence of both advancing alpine treelines as well as rather insignificant responses. In this context, we aim at investigating the sensitivity and responsiveness of the near-natural treeline ecotone in Rolwaling Himal, Nepal, to climate warming. We analysed population densities of tree species along the treeline ecotone from closed forest stands via the krummholz belt to alpine dwarf shrub heaths （3700-4200 m） at 50 plots in 2013 and 2014. We quantified species - environment relationships, i.e. the change of environmental conditions （e.g., nutrient and thermal deficits, plant interactions） across the ecotone by means of redundancy analyses, variation partitioning and distance-based Moran＇s eigenvector maps. In particular, we focus on explaining the high competitiveness of Rhododendron campanulatum forming a dense krummholz belt and on the implications for the responsiveness of Himalayan krummholz treelines to climate change. Results indicate that treeline trees in the ecotone show species-specific responses to the influence of environmental parameters, and that juvenile and adult tree responses are modulated by environmental constraints in differing intensity. Moreover, the species - environment relationships suggest that the investigated krummholz belt will largely prevent the upward migration of other tree constrain the future response species and thus of Himalayan krummholz treelines to climate warming.展开更多
基金the Shanxi Province Science and Technology Project(Grant number:2014091003-0106).
文摘Background:Understanding the spatial pattern and driving factors of forest carbon density in mountainous terrain is of great importance for monitoring forest carbon in support of sustainable forest management for mitigating climate change.Methods:We collected the forest inventory data in 2015 in Shanxi Province,eastern Loess Plateau of China,to explore the spatial pattern and driving factors of biomass carbon density(BCD)for natural and planted coniferous forests using Anselin Local Moran’s I,Local Getis-Ord G*and semivariogram analyses,and multi-group structural equation modeling,respectively.Results:The result of spatial pattern of BCDs for natural forests showed that the BCD was generally higher in the north but lower in the south of Shanxi.The spatial pattern for planted forests was substantially different from that for natural forests.The results of multi-group SEM suggested that elevation(or temperature as the alternative factor of elevation)and stand age were important driving factors of BCD for these two forest types.Compared with other factors,the effects of latitude and elevation on BCD showed much greater difference between these two forest types.The difference in indirect effect of latitude(mainly through affecting elevation and stand age)between natural and planted forests was to some extent a reflection of the difference between the spatial patterns of BCDs for natural and planted forests in Shanxi.Conclusions:The natural coniferous forests had a higher biomass carbon density,a stronger spatial dependency of biomass carbon density relative to planted coniferous forests in Shanxi.Elevation was the most important driving factor,and the effect on biomass carbon density was stronger for natural than planted coniferous forests.Besides,latitude presented only indirect effect on it for the two forest types.
基金supported by W.C.Coker and A.H.Beers fellowships and a Dissertation Completion Fellowship from the University of North Carolina at Chapel Hill to W.X.and a grant from the National Science Foundation(DEB-97-07551)to R.K.P.and D.L.U.
文摘Aims Large hurricanes have profound impacts on temperate forests,but owing to their infrequent nature these effects have rarely been examined in detail.In 1996,Hurricane Fran significantly damaged many long-term tree census plots in the Duke Forest on the North Carolina Piedmont,thereby providing an exceptional opportunity to examine pre-and post-hurricane forest compositional trajectories.Our goal was to examine immediate,short-term(0–4 years)and longer term(;5 year)hurricane-induced structural,spatial and compositional changes in the tree population(stem d.b.h>1 cm)in the context of our detailed,long-term knowledge of the dynamics of these forests.Methods We surveyed stem damage and tree mortality in 34 long-term permanent plots(ca.70-year record;404–1012 m^(2))and 7 large mapped tree stands(ca.20-year record;5250–65000 m^(2))representing both transition-phase,even-aged pine stands and uneven-aged upland hardwood forests.We employed three types of damage measures to quantify stand-level damage severity:percentage of stems damaged,percentage of basal area lost and a‘stand-level damage index’.Second-order spatial analysis(Ripley’s K-function)was used to investigate patterns in tree mortality.Important findings Our study found hurricane effects on the structural attributes of Piedmont forests to be variable and patchy.Changes in tree species composition,however,were modest.Uprooting was the major damage type for the overstory trees[diameter at breast height(d.b.h.)>10 cm]apparently due to the exposure of the crowns to high wind combined with heavy rainfall prior to and during the storm.Saplings,juvenile trees and small trees(1–10 cm d.b.h.)of the understory and midstory were mainly damaged by being pinned or bent by their damaged large neighbors.Hurricane-induced tree mortality varied weakly among species,was positively correlated with pre-hurricane tree size and remained up to 2-fold higher than pre-hurricane background mortality 5 years after the hurricane.Spatial point pattern analysis revealed a patchy distribution of tree mortality during the hurricane sampling interval.Hurricane Fran resulted in a dramatic increase in average gap size from ca.400 m^(2) pre-hurricane to ca 1100 m^(2) after the hurricane,whereas maximum gap sizes reached 18–34 times larger than the pre-hurricane levels.
基金funded by Studienstiftung des deutschen VolkesGerman Research Foundation for funding(DFG,SCHI 436/14-1,BO 1333/4-1,SCHO 739/14-1)
文摘Climate warming is expected to advance treelines to higher elevations. However, empirical studies in diverse mountain ranges give evidence of both advancing alpine treelines as well as rather insignificant responses. In this context, we aim at investigating the sensitivity and responsiveness of the near-natural treeline ecotone in Rolwaling Himal, Nepal, to climate warming. We analysed population densities of tree species along the treeline ecotone from closed forest stands via the krummholz belt to alpine dwarf shrub heaths （3700-4200 m） at 50 plots in 2013 and 2014. We quantified species - environment relationships, i.e. the change of environmental conditions （e.g., nutrient and thermal deficits, plant interactions） across the ecotone by means of redundancy analyses, variation partitioning and distance-based Moran＇s eigenvector maps. In particular, we focus on explaining the high competitiveness of Rhododendron campanulatum forming a dense krummholz belt and on the implications for the responsiveness of Himalayan krummholz treelines to climate change. Results indicate that treeline trees in the ecotone show species-specific responses to the influence of environmental parameters, and that juvenile and adult tree responses are modulated by environmental constraints in differing intensity. Moreover, the species - environment relationships suggest that the investigated krummholz belt will largely prevent the upward migration of other tree constrain the future response species and thus of Himalayan krummholz treelines to climate warming.
