Cactaceae is an important plant family in the semi-arid ecosystems of the Americas.However,few studies have analyzed their responses after wildfires.In this study,we assessed the survival rate and resprouting capacity...Cactaceae is an important plant family in the semi-arid ecosystems of the Americas.However,few studies have analyzed their responses after wildfires.In this study,we assessed the survival rate and resprouting capacity of cacti from different growth forms one year after a wildfire in the Córdoba Mountains,central Argentina.Eight species are present in the study area,which were classified into four growth forms;then we established 158 plots and recorded the status(dead or alive)of each cactus and size-related variables.We also documented microenvironmental characteristics(percentage cover of grasses,forbs,shrubs,rock and bare ground)and topographic information(slope and slope orientation)for each plot,estimating the resprouting capacity of each growth form.Survival rates and resprouting capacity varied among growth forms.The survival rate for arborescent growth form was 25%,while for globose,opuntioid and short columnar forms were 84%,69%and 55%,respectively.Microenvironmental and topographic factors influenced resprouting capacity,though effects varied among growth forms.Globose growth form showed the highest recovery capacity after the wildfire,contrasting with arborescent growth form,of which only 2%of the individuals resprouted,predominantly on south-and north-facing slopes.In contrast,short columnar and opuntioid growth forms showed no significant relationship between survival or resprouting capacity,and the measured variables.These findings provide key insights into the role of fire in shaping cacti populations and highlight the need to consider species-specific and environmental interactions in conservation and management strategies for the Chaco forest.展开更多
Natural regeneration after disturbances is a key phase of forest development,which determines the trajectory of successional changes in tree species composition and diversity.Regenerating trees can originate from eith...Natural regeneration after disturbances is a key phase of forest development,which determines the trajectory of successional changes in tree species composition and diversity.Regenerating trees can originate from either seeds or sprouts produced by disturbed trees with sprouting ability.Although both regeneration strategies often develop and co-occur after a disturbance,they tend to affect forest development differently due to significant functional differences.However,the origin of tree regeneration is rarely distinguished in post-disturbance forest surveys and ecological studies,and the differential roles of seed and sprout regeneration in forest productivity and diversity remain poorly understood.To address these research gaps,we explored the role of sprout and seed regeneration in the formation of woody species diversity and above-ground biomass(AGB)productivity in early-stage forest development.Data were collected in two experimental forest stands in the Czech Republic,where trees were cut with varying intensities with the density of residual(uncut)trees ranging from 0 to 275 trees per hectare.All trees were mapped and their sizes were measured before cutting and then,either as a stump with sprouts or a residual tree,remeasured 11 years later.In addition,all tree saplings were mapped and measured 11 years after logging,and their origin(sprout or seed)was identified.To assess abundances and productivity,we estimated AGB of all2,685 sprouting stumps of 19 woody species and 504 generative(i.e.,seed origin)individuals of 16 woody species,using allometric equations.Mixed-effects models were used to analyze the effects of each regeneration strategy on woody species diversity and the total AGB under varying densities of residual trees.Nonmetric multidimensional scaling was used to evaluate the effect of regeneration strategies on species composition.AGB and diversity of sprouts were significantly higher than those of seed regeneration.Sprouts formed on average97.1%of the total regeneration AGB in H ady and 98.6%in Sobe s ice.The average species richness of sprouts was4.7 in H ady and 2.2 in Sob e sice,while the species richness of seed regeneration averaged 2.1 and 1.1 in H ady and Sob e sice,respectively.Increasing density of residual trees reduced AGB and diversity of both sprouts and seed regeneration,but seed regeneration was affected to a greater extent.Residual trees had an especially strong inhibitory effect on the establishment of seed regeneration.Consequently,seed-originated saplings were nearly absent in plots with high residual tree density,and abundant sprouts accounted for most of the AGB and diversity.However,unlike sprouts whose species composition resembled that of the original stand,seed regeneration brought in new species,enriching the stand?s overall species pool and beta diversity.Our results demonstrated differential roles of sprout and seed regeneration in the early stage of forest succession.Sprout regeneration was the main source of woody AGB productivity as well as species diversity,and its importance increased with the increasing density of standing mature trees.The results indicate the crucial yet previously underestimated role of sprout regeneration in post-disturbance forest dynamics.They suggest that the presence of residual mature trees,whether retained after partial cutting or undisturbed,can substantially suppress seed regeneration while the role of sprout regeneration in early succession becomes more distinctly evident.展开更多
The miombo woodland is one of the most extensive woodlands in Africa, supporting livelihoods based on biomass fuel for millions of rural people. However, there are growing concerns about the sustainability of harvesti...The miombo woodland is one of the most extensive woodlands in Africa, supporting livelihoods based on biomass fuel for millions of rural people. However, there are growing concerns about the sustainability of harvesting for biomass fuel （mainly charcoal）. Thus, the aim of this study was to examine whether regeneration by coppice is a viable option for sustainably managing miombo woodlands for biomass fuel production. We tested the hypotheses that （1） species, stump diameter, stump height and time since cutting significantly affect the number of sprouts per cut stump （coppice density） and mean sprout height （shoot vigour） and （2） higher coppice density reduces shoot vigour due to competition among coppice shoots in a given stump. In an inventory in areas that were harvested for charcoal production by the local people, 369 stumps of 11 species were recorded with mean coppice stumps ranged from 6 to 84. The mean coppice density ranged from 5 to 8 shoots per stump while the mean height of coppice shoots ranged from 46 to 118 cm with marked interspecific variations. Stump size was signifi- cantly and positively correlated with coppice density for some of the species, but not with shoot vigour for the majority of the species. However, shoot vigour was significantly positively correlated to time since cutting of trees for nearly half of the species. Coppice density had a significant negative correlation with shoot vigour for two species, and a positive correlation for one species. In conclusion, the results provide evidence about the importance of coppice management as a win-win strategy for sustaining charcoal-based rural livelihoods and recovering the miombo woodland ecosystem.展开更多
Natural forest recovery on abandoned farmland is hindered by a variety of factors and active restoration plays an important role when quick afforestation is desired. We investigated seedling survival of four transplan...Natural forest recovery on abandoned farmland is hindered by a variety of factors and active restoration plays an important role when quick afforestation is desired. We investigated seedling survival of four transplanted native tree species （Quercus myrsinifolia, Quercus serrata, Aphananthe aspera, and Rhus sylvestris） by experimentally manipulating the vegetation cover, which was mainly dominated by dwarf bamboo （Pleioblastus chino）, and herbivore access to the planting sites on farmland that had been abandoned for 15 years at the start of the study. Few transplanted seedlings of any species survived under intact vegetation cover, irrespective of herbivore presence. In gaps in the vegetation cover, winter browsing by Japanese hare （Lepus brachyurus） damaged all species. However, lower browsing frequency and higher resprouting ability after grazing of the seedlings enabled both Quercus species to survive better than the other species. These results indicate that dwarf bamboo and the hare jointly limit the establishment of native trees in old fields. If active afforestation by transplanting seedlings at sites dominated by dwarf bamboo is planned, a combination of vegetation removal, selection of suitable species, and temporary seedling protection will be most effective.展开更多
Background:In fire-prone ecosystems,plant species having different post-fire regeneration strategies(PFRS)coexist at the local scale while showing different growth dynamics.To evaluate the effect of PFRS on species re...Background:In fire-prone ecosystems,plant species having different post-fire regeneration strategies(PFRS)coexist at the local scale while showing different growth dynamics.To evaluate the effect of PFRS on species regeneration,we investigated the plant communities burned in different years in the central Yunnan Province,Southwest China.Several indicators describing plant growth and population importance were measured to compare the regeneration of four dominant tree species,including one facultative seeders(FS)and three obligate resprouters(OR).Partial correlation and mixed linear effect modeling were applied to disentangle the contribution of intrinsic and environmental factors to the interspecific variation in post-fire regeneration.Results:We identified two subtypes of plant growth strategy in the early post-fire stage for OR species;i.e.,number growth(ORþN)priority and height growth(ORþH)priority for sprouting stems.Generally,the FS and OR species varied in height growth rate with different temporal dynamics.The ORþN species occupied post-fire space horizontally with more resprouts and larger coverage than ORþH and FS species at the earlier stage.In contrast,the ORþH species generally had far less resprouts per clump,more variations in stem height and basal diameter.Factor analysis showed that the variation of post-fire plant regeneration was not effectively explained by environmental factors(R2<20%);however,the linear mixed models with the modified PFRS as a random effect substantially increased the explanation.Conclusions:The differentiated regeneration dynamics and growth priorities in the four dominant tree species indicated a critical dichotomy of habitat occupation strategy for the resprouter species during the early stage of post-fire forest restoration.Our study uncovered a trade-off between height versus number growth priority in the post-fire tree growth strategy and provides a novel perspective in understanding the living space occupying(niche partitioning)process and species coexistence in post-fire forest community assembly.展开更多
Background Disturbance is a key driver of changes in terrestrial ecosystems,especially in water limited regions.In the desert ecosystem of Northwest China,shrubs are often foraged by camels and this causes the shrubs ...Background Disturbance is a key driver of changes in terrestrial ecosystems,especially in water limited regions.In the desert ecosystem of Northwest China,shrubs are often foraged by camels and this causes the shrubs lost their aboveground tissues.Although the aboveground tissue could recover after the disturbance,the mechanisms of resprouts'recovery after the disturbance are still poorly understood.We investigated the morphological and physiological characteristics and root water uptake sources of resprouts and non-disturbed seedlings of four desert shrub species that were often foraged by camels.Results The results showed that the resprouts grew rapidly after the removal of aboveground tissue.The height and aboveground biomass of resprouts reached the level of 5-year-old seedlings following a growing season.Compared to un-disturbed seedlings,higher leaf water potential,leaf hydraulic conductance and photosynthesis rate were observed in resprouts,indicating that resprouts grew rapidly after disturbance.Furthermore,we found that the root water uptake source did not change after disturbance.This indicated that the roots of resprouts kept intact water uptake capacity after disturbance,which could keep supplying sufficient water to the aboveground tissue.Due to the removal of aboveground tissue of the resprouts,the water demand of aboveground tissue decreased,which induced an imbalance of water supply from roots to demand of aboveground tissues of resprouts.This explained the improved physiological performance and rapid recovery of resprouts after disturbance.Conclusions The imbalance of water supply to demand contributes to the rapid recovery of desert shrubs after disturbance.The findings provide insight into the eco-physiological mechanism for the maintenance of desert ecosystems that are facing disturbance.展开更多
基金supported by grants from the Research Committee of the Cactus and Succulent Society of America and Secretaría de Ciencia y Tecnología-Universidad Nacional de Córdoba,and a PIP-CONICET grant[11220220100196],Argentina.
文摘Cactaceae is an important plant family in the semi-arid ecosystems of the Americas.However,few studies have analyzed their responses after wildfires.In this study,we assessed the survival rate and resprouting capacity of cacti from different growth forms one year after a wildfire in the Córdoba Mountains,central Argentina.Eight species are present in the study area,which were classified into four growth forms;then we established 158 plots and recorded the status(dead or alive)of each cactus and size-related variables.We also documented microenvironmental characteristics(percentage cover of grasses,forbs,shrubs,rock and bare ground)and topographic information(slope and slope orientation)for each plot,estimating the resprouting capacity of each growth form.Survival rates and resprouting capacity varied among growth forms.The survival rate for arborescent growth form was 25%,while for globose,opuntioid and short columnar forms were 84%,69%and 55%,respectively.Microenvironmental and topographic factors influenced resprouting capacity,though effects varied among growth forms.Globose growth form showed the highest recovery capacity after the wildfire,contrasting with arborescent growth form,of which only 2%of the individuals resprouted,predominantly on south-and north-facing slopes.In contrast,short columnar and opuntioid growth forms showed no significant relationship between survival or resprouting capacity,and the measured variables.These findings provide key insights into the role of fire in shaping cacti populations and highlight the need to consider species-specific and environmental interactions in conservation and management strategies for the Chaco forest.
基金supported by an Internal Grant Agency CULS project No.A_21_06by the grant INTER-TRANSFER LTT20017 provided by the Ministry of Education,Youth and Sports of the Czech Republic.
文摘Natural regeneration after disturbances is a key phase of forest development,which determines the trajectory of successional changes in tree species composition and diversity.Regenerating trees can originate from either seeds or sprouts produced by disturbed trees with sprouting ability.Although both regeneration strategies often develop and co-occur after a disturbance,they tend to affect forest development differently due to significant functional differences.However,the origin of tree regeneration is rarely distinguished in post-disturbance forest surveys and ecological studies,and the differential roles of seed and sprout regeneration in forest productivity and diversity remain poorly understood.To address these research gaps,we explored the role of sprout and seed regeneration in the formation of woody species diversity and above-ground biomass(AGB)productivity in early-stage forest development.Data were collected in two experimental forest stands in the Czech Republic,where trees were cut with varying intensities with the density of residual(uncut)trees ranging from 0 to 275 trees per hectare.All trees were mapped and their sizes were measured before cutting and then,either as a stump with sprouts or a residual tree,remeasured 11 years later.In addition,all tree saplings were mapped and measured 11 years after logging,and their origin(sprout or seed)was identified.To assess abundances and productivity,we estimated AGB of all2,685 sprouting stumps of 19 woody species and 504 generative(i.e.,seed origin)individuals of 16 woody species,using allometric equations.Mixed-effects models were used to analyze the effects of each regeneration strategy on woody species diversity and the total AGB under varying densities of residual trees.Nonmetric multidimensional scaling was used to evaluate the effect of regeneration strategies on species composition.AGB and diversity of sprouts were significantly higher than those of seed regeneration.Sprouts formed on average97.1%of the total regeneration AGB in H ady and 98.6%in Sobe s ice.The average species richness of sprouts was4.7 in H ady and 2.2 in Sob e sice,while the species richness of seed regeneration averaged 2.1 and 1.1 in H ady and Sob e sice,respectively.Increasing density of residual trees reduced AGB and diversity of both sprouts and seed regeneration,but seed regeneration was affected to a greater extent.Residual trees had an especially strong inhibitory effect on the establishment of seed regeneration.Consequently,seed-originated saplings were nearly absent in plots with high residual tree density,and abundant sprouts accounted for most of the AGB and diversity.However,unlike sprouts whose species composition resembled that of the original stand,seed regeneration brought in new species,enriching the stand?s overall species pool and beta diversity.Our results demonstrated differential roles of sprout and seed regeneration in the early stage of forest succession.Sprout regeneration was the main source of woody AGB productivity as well as species diversity,and its importance increased with the increasing density of standing mature trees.The results indicate the crucial yet previously underestimated role of sprout regeneration in post-disturbance forest dynamics.They suggest that the presence of residual mature trees,whether retained after partial cutting or undisturbed,can substantially suppress seed regeneration while the role of sprout regeneration in early succession becomes more distinctly evident.
基金financially supported by the Swedish Research Link
文摘The miombo woodland is one of the most extensive woodlands in Africa, supporting livelihoods based on biomass fuel for millions of rural people. However, there are growing concerns about the sustainability of harvesting for biomass fuel （mainly charcoal）. Thus, the aim of this study was to examine whether regeneration by coppice is a viable option for sustainably managing miombo woodlands for biomass fuel production. We tested the hypotheses that （1） species, stump diameter, stump height and time since cutting significantly affect the number of sprouts per cut stump （coppice density） and mean sprout height （shoot vigour） and （2） higher coppice density reduces shoot vigour due to competition among coppice shoots in a given stump. In an inventory in areas that were harvested for charcoal production by the local people, 369 stumps of 11 species were recorded with mean coppice stumps ranged from 6 to 84. The mean coppice density ranged from 5 to 8 shoots per stump while the mean height of coppice shoots ranged from 46 to 118 cm with marked interspecific variations. Stump size was signifi- cantly and positively correlated with coppice density for some of the species, but not with shoot vigour for the majority of the species. However, shoot vigour was significantly positively correlated to time since cutting of trees for nearly half of the species. Coppice density had a significant negative correlation with shoot vigour for two species, and a positive correlation for one species. In conclusion, the results provide evidence about the importance of coppice management as a win-win strategy for sustaining charcoal-based rural livelihoods and recovering the miombo woodland ecosystem.
文摘Natural forest recovery on abandoned farmland is hindered by a variety of factors and active restoration plays an important role when quick afforestation is desired. We investigated seedling survival of four transplanted native tree species （Quercus myrsinifolia, Quercus serrata, Aphananthe aspera, and Rhus sylvestris） by experimentally manipulating the vegetation cover, which was mainly dominated by dwarf bamboo （Pleioblastus chino）, and herbivore access to the planting sites on farmland that had been abandoned for 15 years at the start of the study. Few transplanted seedlings of any species survived under intact vegetation cover, irrespective of herbivore presence. In gaps in the vegetation cover, winter browsing by Japanese hare （Lepus brachyurus） damaged all species. However, lower browsing frequency and higher resprouting ability after grazing of the seedlings enabled both Quercus species to survive better than the other species. These results indicate that dwarf bamboo and the hare jointly limit the establishment of native trees in old fields. If active afforestation by transplanting seedlings at sites dominated by dwarf bamboo is planned, a combination of vegetation removal, selection of suitable species, and temporary seedling protection will be most effective.
基金supported by the National Natural Science Foundation of China(41971228)the National Key R and D Program of the Ministry of Science and Technology of China(2017YFC0505200).
文摘Background:In fire-prone ecosystems,plant species having different post-fire regeneration strategies(PFRS)coexist at the local scale while showing different growth dynamics.To evaluate the effect of PFRS on species regeneration,we investigated the plant communities burned in different years in the central Yunnan Province,Southwest China.Several indicators describing plant growth and population importance were measured to compare the regeneration of four dominant tree species,including one facultative seeders(FS)and three obligate resprouters(OR).Partial correlation and mixed linear effect modeling were applied to disentangle the contribution of intrinsic and environmental factors to the interspecific variation in post-fire regeneration.Results:We identified two subtypes of plant growth strategy in the early post-fire stage for OR species;i.e.,number growth(ORþN)priority and height growth(ORþH)priority for sprouting stems.Generally,the FS and OR species varied in height growth rate with different temporal dynamics.The ORþN species occupied post-fire space horizontally with more resprouts and larger coverage than ORþH and FS species at the earlier stage.In contrast,the ORþH species generally had far less resprouts per clump,more variations in stem height and basal diameter.Factor analysis showed that the variation of post-fire plant regeneration was not effectively explained by environmental factors(R2<20%);however,the linear mixed models with the modified PFRS as a random effect substantially increased the explanation.Conclusions:The differentiated regeneration dynamics and growth priorities in the four dominant tree species indicated a critical dichotomy of habitat occupation strategy for the resprouter species during the early stage of post-fire forest restoration.Our study uncovered a trade-off between height versus number growth priority in the post-fire tree growth strategy and provides a novel perspective in understanding the living space occupying(niche partitioning)process and species coexistence in post-fire forest community assembly.
基金National Natural Science Foundation of China(Grant Nos.32171876,42230720)the Gansu Province Science and Technology Program(23JRRA627)
文摘Background Disturbance is a key driver of changes in terrestrial ecosystems,especially in water limited regions.In the desert ecosystem of Northwest China,shrubs are often foraged by camels and this causes the shrubs lost their aboveground tissues.Although the aboveground tissue could recover after the disturbance,the mechanisms of resprouts'recovery after the disturbance are still poorly understood.We investigated the morphological and physiological characteristics and root water uptake sources of resprouts and non-disturbed seedlings of four desert shrub species that were often foraged by camels.Results The results showed that the resprouts grew rapidly after the removal of aboveground tissue.The height and aboveground biomass of resprouts reached the level of 5-year-old seedlings following a growing season.Compared to un-disturbed seedlings,higher leaf water potential,leaf hydraulic conductance and photosynthesis rate were observed in resprouts,indicating that resprouts grew rapidly after disturbance.Furthermore,we found that the root water uptake source did not change after disturbance.This indicated that the roots of resprouts kept intact water uptake capacity after disturbance,which could keep supplying sufficient water to the aboveground tissue.Due to the removal of aboveground tissue of the resprouts,the water demand of aboveground tissue decreased,which induced an imbalance of water supply from roots to demand of aboveground tissues of resprouts.This explained the improved physiological performance and rapid recovery of resprouts after disturbance.Conclusions The imbalance of water supply to demand contributes to the rapid recovery of desert shrubs after disturbance.The findings provide insight into the eco-physiological mechanism for the maintenance of desert ecosystems that are facing disturbance.
