This study investigated forest recovery in the Atlantic Rainforest and Rupestrian Grassland of Brazil using the diffusive-logistic growth(DLG)model.This model simulates vegetation growth in the two mountain biomes con...This study investigated forest recovery in the Atlantic Rainforest and Rupestrian Grassland of Brazil using the diffusive-logistic growth(DLG)model.This model simulates vegetation growth in the two mountain biomes considering spatial location,time,and two key parameters:diffusion rate and growth rate.A Bayesian framework is employed to analyze the model's parameters and assess prediction uncertainties.Satellite imagery from 1992 and 2022 was used for model calibration and validation.By solving the DLG model using the finite difference method,we predicted a 6.6%–51.1%increase in vegetation density for the Atlantic Rainforest and a 5.3%–99.9%increase for the Rupestrian Grassland over 30 years,with the latter showing slower recovery but achieving a better model fit(lower RMSE)compared to the Atlantic Rainforest.The Bayesian approach revealed well-defined parameter distributions and lower parameter values for the Rupestrian Grassland,supporting the slower recovery prediction.Importantly,the model achieved good agreement with observed vegetation patterns in unseen validation data for both biomes.While there were minor spatial variations in accuracy,the overall distributions of predicted and observed vegetation density were comparable.Furthermore,this study highlights the importance of considering uncertainty in model predictions.Bayesian inference allowed us to quantify this uncertainty,demonstrating that the model's performance can vary across locations.Our approach provides valuable insights into forest regeneration process uncertainties,enabling comparisons of modeled scenarios at different recovery stages for better decision-making in these critical mountain biomes.展开更多
Species composition, diversity and population structure of woody species recovered on three abandoned agricultural fields after 4, 9 and 14 years were characterized. Seedlings, saplings/poles and mature trees were ide...Species composition, diversity and population structure of woody species recovered on three abandoned agricultural fields after 4, 9 and 14 years were characterized. Seedlings, saplings/poles and mature trees were identified and counted in 70 plots of 100 m^2 in each abandoned site. A total of 13, 29 and 22 families represented by 17, 48 and 44 species were registered in 4-, 9- and 14-year-old stands, respectively. There was a shift in dominant species across successional stages. Lonchocarpus acuminatus had the highest importance value in the 4-year old stand, whereas, Myrospermun frutescens, Guazurna ulmifolia and Cordia alliodora had the highest importance value in the 9-year-old-stand and Caesaeria corymbosa, Muntingia calabura, Gliricidia sepium and Tabebuia rosea in the 14-year-old stand. The total stem density increased from 5011 to 9631 individuals per hectare as the age of abandonment increased from 4 to 14 years. The total basal area of individuals _〉 I cm d.b.h, also increased with the age of abandonment. Overall, small individuals （〈 10 cm dbh） contributed to more than half of the total basal area. Species diversity was the highest in the 9-year old stand followed by 14- and 4-year-old stands. We concluded that floristic composition of secondary forests recovers rapidly to the mature forest level compared to structural attributes, which is consistent with the general successional trajectories of tropical dry forest.展开更多
Species composition, diversity and population structure of woody species recovered on three abandoned agricultural fields after 4, 9 and 14 years were characterized. Seedlings, saplings/poles and mature trees were ide...Species composition, diversity and population structure of woody species recovered on three abandoned agricultural fields after 4, 9 and 14 years were characterized. Seedlings, saplings/poles and mature trees were identified and counted in 70 plots of 100 m2 in each abandoned site. A total of 13, 29 and 22 families represented by 17, 48 and 44 species were registered in 4-, 9-and 14-year-old stands, respectively. There was a shift in dominant species across successional stages. Lonchocarpus acuminatus had the highest importance value in the 4-year old stand, whereas, Myrospermun frutescens, Guazuma ulmifolia and Cordia alliodora had the highest importance value in the 9-year-old-stand and Caesaeria corymbosa, Muntingia calabura, Gliricidia sepium and Tabebuia rosea in the 14-year-old stand. The total stem density increased from 5011 to 9631 individuals per hectare as the age of abandonment increased from 4 to 14 years. The total basal area of individuals ≥ 1cm d.b.h. also increased with the age of abandonment. Overall, small individuals (< 10 cm dbh) contributed to more than half of the total basal area. Species diversity was the highest in the 9-year old stand followed by 14-and 4-year-old stands. We concluded that floristic composition of secondary forests recovers rapidly to the mature forest level compared to structural attributes, which is consistent with the general successional trajectories of tropical dry forest.展开更多
Forest recovery plays a critical role in regulating eco-hydrological processes in forested watersheds.However,characteristics of the intra-annual runoff variation associated with different forest recovery patterns rem...Forest recovery plays a critical role in regulating eco-hydrological processes in forested watersheds.However,characteristics of the intra-annual runoff variation associated with different forest recovery patterns remain poorly understood.In this study,three forest change periods were identified,the baseline period(1961-1985),reforestation period(1986-2000)and fruit tree planting period(2001-2016).We selected the magnitude of seasonal runoff(wet and dry seasons)and distribution characteristics,i.e.,non-uniformity coefficient(C_(v)),complete accommodation coefficient(C_(r)),concentration ratio(C_(n)),concentration period(C_(d)),absolute variation ratio(ΔR)and relative variation ratio(C_(max)).The pair-wise approach evaluated the intra-annual runoff variation characteristics between forest change periods.Results indicate that reforestation decreased wet season runoff and increased dry season runoff.In contrast,fruit tree planting increased wet season runoff and had no significant effect on dry season runoff.For intra-annual runoff distribution characteristics,reforestation significantly reduced the C_(v),C_(r),C_(n)and C_(max).Distribution of the intra-annual runoff in the fruit tree planting period was not significantly different from the baseline.We concluded that reforestation reduced the occurance of extreme water conditions in wet and dry seasons and effectively increased the stability of the intra-annual runoff.In contrast,fruit tree planting increased instability and fluctuation of the intra-annual runoff after reforestation.The characteristics of the intra-annual runoff to fruit tree planting was similar to those of the baseline.Therefore,adopting fruit tree planting practices to regulate intra-annual runoff characteristics may not be a practical approach,and impacts of different reforestation practices should be ascertained in our study region.The implications of this study should guide regional land-water management,and this study adds to the understanding of the impacts gained in forest cover on hydrology.展开更多
Analysis of the change in forest cover is important to determine stand dynamics and the processes involved in disturbance and recovery.Forests of the core zone of the Monarch Butterfly Biosphere Reserve were studied u...Analysis of the change in forest cover is important to determine stand dynamics and the processes involved in disturbance and recovery.Forests of the core zone of the Monarch Butterfly Biosphere Reserve were studied using photo interpretation techniques,considering biennial changes between 1999 and 2013 and changes over the whole period of study 1999–2013.Error matrices were elaborated to determine the processes of change involved in both recovery and disturbance.The biennial changes for the whole period amounted to 2274 ha;343 ha accounted as degraded in more than one biennial period.The total changes in forest cover between 1999 and 2013 involved 4902 ha,out of which,2912 ha were affected by disturbance,and 1990 ha were recovered.For density and 2013 vegetation cover maps,the overall accuracy was 95.6%and 90.2%,respectively.By combining both maps,gradual processes were revealed that were not evident in separate analyses.This methodology is useful for the management and conservation of natural protected areas.展开更多
Secondary forests account for a large amount of subtropical forest due to persistent anthropogenic disturbance in China.The interaction between vegetation and soil during recovery process is rather complex and depende...Secondary forests account for a large amount of subtropical forest due to persistent anthropogenic disturbance in China.The interaction between vegetation and soil during recovery process is rather complex and dependent on forest conditions.Understanding how vegetation and soil properties changes and how their relationship develops in secondary forests is key to effective forest restoration and management.Here we explored the patterns of vegetation and soil properties as well as their correlations during forest recovery process in a subtropical forest in south China.Plots of three forest types,i.e.,broadleaf-conifermixedforest,broadleaved forest and old growth stand,were established to represent the recovery stages.The results showed that diversity patterns in the tree,shrub and herb layers were different:in the tree layer the species diversity peaked at the intermediate stage,while in the understory layers it decreased chronologically.Most of the soil factors showed an increasing trend,and different effects of soil factors were found for the three layers as well as for the two spatial scales.Together,our results suggested that vegetation and soil might be interdependent during the recovery course.Further studies are needed on exploring how vegetation interplays with soil at different scales and how nutrient limitations affects the vegetation development in a chronosequence.展开更多
Climate change,a recognized critical environmental issue,plays an important role in regulating the structure and function of forest ecosystems by altering forest disturbance and recovery regimes.This research focused ...Climate change,a recognized critical environmental issue,plays an important role in regulating the structure and function of forest ecosystems by altering forest disturbance and recovery regimes.This research focused on exploring the statistical relationships between meteorological and topographic variables and the recovery characteristics following disturbance of plantation forests in southern China.We used long-term Landsat images and the vegetation change tracker algorithm to map forest disturbance and recovery events in the study area from 1988 to 2016.Stepwise multiple linear regression(MLR),random forest(RF)regression,and support vector machine(SVM)regression were used in conjunction with climate variables and topographic factors to model short-term forest recovery using the normalized difference vegetation index(NDVI).The results demonstrated that the regenerating forests were sensitive to the variation in temperature.The fitted results suggested that the relationship between the NDVI values of the forest areas and the post-disturbance climatic and topographic factors differed in regression algorithms.The RF regression yielded the best performance with an R2 value of 0.7348 for the validation accuracy.This indicated that slope and temperature,especially high temperatures,had substantial effects on post-disturbance vegetation recovery in southern China.For other mid-subtropical monsoon regions with intense light and heat and abundant rainfall,the information will also contribute to appropriate decisions for forest managers on forest recovery measures.Additionally,it is essential to explore the relationships between forest recovery and climate change of different vegetation types or species for more accurate and targeted forest recovery strategies.展开更多
Montane forest ecosystems support biodiversity and provide varied ecosystem services to adjacent and downstream human communities. However, human-induced disturbances are common in many of these ecosystems, threatenin...Montane forest ecosystems support biodiversity and provide varied ecosystem services to adjacent and downstream human communities. However, human-induced disturbances are common in many of these ecosystems, threatening their capacity to sustain their functions. This study assessed the status of woody vegetation and livestock use of a Kenyan montane forest 10 years after government-sanctioned cessation of human encroachment. The findings can inform suitable interventions that support recovery of abandoned forest settlements subjected to continuous anthropogenic disturbances. Selected woody vegetation attributes and livestock disturbance indicators were assessed across three human-driven disturbance regimes (light, moderate and heavy) using stratified-systematic sampling technique. Data on the extent of community dependence on forest grazing were collected from 381 randomly selected forest adjacent households using semi-structured questionnaires. Information on the palatability of plants to livestock was obtained from Focus Group Discussions. Vegetation data were analyzed using linear mixed models, while descriptive analysis was applied on household survey data. A total of 33 woody plant species belonging to 22 families were identified, out of which 55% were perceived to be unpalatable to livestock. Species richness, species diversity, stem density and basal areas declined significantly with increasing levels of disturbance. Specifically, these attributes were 59% - 98% lower in heavily disturbed sites than in moderately and lightly disturbed sites. A vast majority (88%) of the sampled households grazed their livestock in the forest throughout the year. Evidence from this study indicates that intense past and ongoing anthropogenic disturbances caused significant negative effects on the forest vegetation condition, and lowered its capacity to recover. Forest managers should prioritize minimizing recurrent anthropogenic disturbances as the forest recovers to ensure successful succession and sustainable provision of ecosystem services.展开更多
Forest disturbance plays a vital role in modulating carbon storage,biodiversity and climate change.Yearly Landsat imagery from 1986 to 2015 of a typical plantation region in the northern Guangdong province of southern...Forest disturbance plays a vital role in modulating carbon storage,biodiversity and climate change.Yearly Landsat imagery from 1986 to 2015 of a typical plantation region in the northern Guangdong province of southern China was used as a case study.A Landsat time series stack(LTSS) was fed to the vegetation change tracker model(VCT) to map long-term changes in plantation forests' disturbance and recovery,followed by an intensive validation and a continuous 27-yr change analysis on disturbance locations,magnitudes and rates of plantations' disturbance and recovery.And the validation results of the disturbance year maps derived from five randomly identified sample plots with 25 km^2 located at the four corners and the center of the scene showed the majority of the spatial agreement measures ranged from 60% to 83%.A confusion matrix summary of the accuracy measures for all four validation sites in Fogang County showed that the disturbance year maps had an overall accuracy estimate of 71.70%.Forest disturbance rates' change trend was characterized by a decline first,followed by an increase,then giving way to a decline again.An undulated and gentle decreasing trend of disturbance rates from the highest value of 3.95% to the lowest value of 0.76% occurred between 1988 and 2001,disturbance rate of 4.51% in 1994 was a notable anomaly,while after 2001 there was a sharp ascending change,forest disturbance rate spiked in 2007(5.84%).After that,there was a significant decreasing trend up to the lowest value of 1.96% in 2011 and a slight ascending trend from 2011 to 2015(2.59%).Two obvious spikes in post-disturbance recovery rates occurred in 1995(0.26%) and 2008(0.41%).Overall,forest recovery rates were lower than forest disturbance rates.Moreover,forest disturbance and recovery detection based on VCT and the Landsat-based detections of trends in disturbance and recovery(LandT rendr) algorithms in Fogang County have been conducted,with LandT rendr finding mostly much more disturbance than VCT.Overall,disturbances and recoveries in northern Guangdong were triggered mostly by timber needs,policies and decisions of the local governments.This study highlights that a better understanding about plantations' changes would provide a critical foundation for local forest management decisions in the southern China.展开更多
Monitoring forest disturbances is important for understanding changes in ecosystems. The 1986 Typhoon Vera was a serious disturbance that severely impacted the forest ecosystems of Changbai Mountain National Nature Re...Monitoring forest disturbances is important for understanding changes in ecosystems. The 1986 Typhoon Vera was a serious disturbance that severely impacted the forest ecosystems of Changbai Mountain National Nature Reserve. Although the typhoon disturbance occurred more than two decades ago, the effects of the typhoon still remain within the study area. Few studies have focused on mapping and assessing disturbances across broad spatial and temporal scales. For this study, we first generated a map of forest composition prior to the typhoon disturbance, which served as a baseline data for the extraction of disturbed area. Then, the Disturbance Index(DI) method was tested for mapping the extent and magnitude of disturbance in the study area by applying a Tasseled Cap transformation to the Landsat imagery. The Landsatbased DI method estimated that an area of 13,764.78 ha of forest was disturbed by the typhoon. Based on visual assessments, these results correspond closely with the reference map derived from ground surveys. These results also revealed the influence of local topographic features on the distribution of windthrow areas. Windthrow areas were more pronounced inareas with elevations ranging from 1,000 to 2,000 m, slopes of less than 10 degrees, and southwestern to northwestern aspects. In addition, the relatively long(25 years) post-typhoon recovery period assessed by this study provided a more comprehensive analysis of the dynamics of forest recovery processes over time. Windthrow areas did not recover immediately after the typhoon, likely due to forest management practices enacted at the time. So far, forest recovery has proceeded more rapidly at elevations below 1,400 m, particularly on western slopes within the study area. Finally, a time series of DI values within the study period suggests a secondary disturbance may have occurred between 2000 and 2001.展开更多
Understanding how soil fertility changes due to environmental conditions and stand-age-dependent forest attributes is important for local-scale forest restoration.We evaluated the effects of stand-age-dependent forest...Understanding how soil fertility changes due to environmental conditions and stand-age-dependent forest attributes is important for local-scale forest restoration.We evaluated the effects of stand-age-dependent forest attributes(plant community composition and litter stock)on soil and technosol fertility across two second-growth Atlantic forests(SGF)after the deposition of mining tailings in Mariana,southeastern Brazil.We hypothesized that technosol fertility in the SGF tailings is positively affected by plant community composition variability,stand age,and litter stock.We used total exchangeable bases and organic matter as fertility indicators for technosol and soil,and species composition and litter stock as stand-age-dependent forest attributes.Our results showed significant differences in the stand-age-dependent forest attributes and soil chemical properties between the two forest patches(SGF tailing and SGF non-tailing)evaluated.Thus,there was a marked gradient of litter storage and fertility between soil and technosol that can be important forest recovery indicators for the affected plant communities.Furthermore,according to the tested models,we corroborated the hypothesis that technosol fertility is positively affected by stand age,plant community composition variability,and litter stock,which may contribute considerably to forest recovery on tailings.Our results demonstrate that the fertility predictors analyzed to explain the forest recovery on tailings can also be considered as ecological indicators for assessing forest restoration in areas impacted by mining tailings in Mariana.展开更多
We investigated the effects of grazing on natural regeneration, quantity, and diversity of woody species and dominant herb species in Kheyroud forest in northern Iran. We sampled vegetation in 5m2 plots in custom unit...We investigated the effects of grazing on natural regeneration, quantity, and diversity of woody species and dominant herb species in Kheyroud forest in northern Iran. We sampled vegetation in 5m2 plots in custom units, which are demarcated resource areas traditionally used by local livestock producers. The authors quantified number of species, height of seedlings, and diameter of seedlings. Height classes were 0-30 cm, 30-130 cm, and 〉130 cm, and diameter classes were 0-2.5 cm, 2.5-5 cm and 5-7.5 cm. The density of seedlings declined with distance from corral until reaching the custom unit boundary. Most seedlings had diameters of 0-2.5 cm and heights of 0-30 cm. Predominant species, Carpinus betulus and Acer capadocicum, were in plots near the centers of custom units, Fagus orientalis, Acer velutinum, Quercus castanifolia species were dominant in plots near the custom unit boundary. Plant species such as Oplismenus undulatifolius, Euphorbia amygdaloides, Rubusfrutieos and Pteridium aquilinum were dominant in plots nearer to forest corral. Healthy seedlings were more numerous in plots nearest the corral, while defective and deformed seedlings were more abundant away from the corral. We conclude that grazing had negative effects on the quantity and quality of vegetative regeneration. Continuation of overgrazing will not only endanger the sustainability of forest ecosystems, but also will increase the challenge of sustainable forest management.展开更多
Aims Human land use such as agriculture and logging can have cascad-ing effects on the environment and severely influence forest eco-systems by altering structure,species composition and community processes.These acti...Aims Human land use such as agriculture and logging can have cascad-ing effects on the environment and severely influence forest eco-systems by altering structure,species composition and community processes.These activities may have long-term consequences,which impact forest recovery.We investigated the legacy of his-torical anthropogenic land use on the current reproductive effort(RE)and success of the understory,myco-heterotrophic orchid,Wullschlaegelia calcarata in Puerto Rico’s tropical rain forest after 80 years of forest recovery.Methods Our study site was the 16-ha Luquillo Forest Dynamics Plot in the Luquillo Experimental Forest.We used six 10 m×500 m transect lines that spanned areas with differing levels of historic canopy coverage which are correlated with land use history.We recorded the abundance of W.calcarata plants and measured shoot height,number of flowers,fruit set for all plants and seed set from the most mature,undehisced fruit on a random subset of plants measured.We sought to determine whether or not there is a legacy of land use history on the RE and success of W.calcarata.Of the varying degrees of historic disturbance,we predicted that RE and success would be highest in minimally disturbed old-growth forest,and that soil type differences would be insufficient to affect RE or success.Important Findings We found 1607 plants of W.calcarata,and only one was detected in the most historically disturbed area of the forest.The orchids were most abundant in the two least historically disturbed sites.However,the prevailing trend in all measures of RE is in the opposite direction with greater RE in the forest plots with intermediate levels of histori-cal disturbance.Furthermore,the best model(as a function of AICc and weights)to predict RE is a combination of soil type and cover class.Nevertheless,our measures of reproductive success(fruit and seed set)were best in the least historically disturbed sites and were not associated with soil type.Thus,the best sites for growth are not always the same as those for abundance and reproduction,and after>80 years of recovery,components of the rainforest community have not fully recovered.展开更多
基金financial support from the Brazilian National Council for Scientific and Technological Development(CNPq)and the Federal University of Ouro PretoFinancial support from the Minas Gerais Research Foundation(FAPEMIG)under grant number APQ-06559-24 is also gratefully acknowledged。
文摘This study investigated forest recovery in the Atlantic Rainforest and Rupestrian Grassland of Brazil using the diffusive-logistic growth(DLG)model.This model simulates vegetation growth in the two mountain biomes considering spatial location,time,and two key parameters:diffusion rate and growth rate.A Bayesian framework is employed to analyze the model's parameters and assess prediction uncertainties.Satellite imagery from 1992 and 2022 was used for model calibration and validation.By solving the DLG model using the finite difference method,we predicted a 6.6%–51.1%increase in vegetation density for the Atlantic Rainforest and a 5.3%–99.9%increase for the Rupestrian Grassland over 30 years,with the latter showing slower recovery but achieving a better model fit(lower RMSE)compared to the Atlantic Rainforest.The Bayesian approach revealed well-defined parameter distributions and lower parameter values for the Rupestrian Grassland,supporting the slower recovery prediction.Importantly,the model achieved good agreement with observed vegetation patterns in unseen validation data for both biomes.While there were minor spatial variations in accuracy,the overall distributions of predicted and observed vegetation density were comparable.Furthermore,this study highlights the importance of considering uncertainty in model predictions.Bayesian inference allowed us to quantify this uncertainty,demonstrating that the model's performance can vary across locations.Our approach provides valuable insights into forest regeneration process uncertainties,enabling comparisons of modeled scenarios at different recovery stages for better decision-making in these critical mountain biomes.
文摘Species composition, diversity and population structure of woody species recovered on three abandoned agricultural fields after 4, 9 and 14 years were characterized. Seedlings, saplings/poles and mature trees were identified and counted in 70 plots of 100 m^2 in each abandoned site. A total of 13, 29 and 22 families represented by 17, 48 and 44 species were registered in 4-, 9- and 14-year-old stands, respectively. There was a shift in dominant species across successional stages. Lonchocarpus acuminatus had the highest importance value in the 4-year old stand, whereas, Myrospermun frutescens, Guazurna ulmifolia and Cordia alliodora had the highest importance value in the 9-year-old-stand and Caesaeria corymbosa, Muntingia calabura, Gliricidia sepium and Tabebuia rosea in the 14-year-old stand. The total stem density increased from 5011 to 9631 individuals per hectare as the age of abandonment increased from 4 to 14 years. The total basal area of individuals _〉 I cm d.b.h, also increased with the age of abandonment. Overall, small individuals （〈 10 cm dbh） contributed to more than half of the total basal area. Species diversity was the highest in the 9-year old stand followed by 14- and 4-year-old stands. We concluded that floristic composition of secondary forests recovers rapidly to the mature forest level compared to structural attributes, which is consistent with the general successional trajectories of tropical dry forest.
基金supported by the Swedish International Development Agency (Sida)
文摘Species composition, diversity and population structure of woody species recovered on three abandoned agricultural fields after 4, 9 and 14 years were characterized. Seedlings, saplings/poles and mature trees were identified and counted in 70 plots of 100 m2 in each abandoned site. A total of 13, 29 and 22 families represented by 17, 48 and 44 species were registered in 4-, 9-and 14-year-old stands, respectively. There was a shift in dominant species across successional stages. Lonchocarpus acuminatus had the highest importance value in the 4-year old stand, whereas, Myrospermun frutescens, Guazuma ulmifolia and Cordia alliodora had the highest importance value in the 9-year-old-stand and Caesaeria corymbosa, Muntingia calabura, Gliricidia sepium and Tabebuia rosea in the 14-year-old stand. The total stem density increased from 5011 to 9631 individuals per hectare as the age of abandonment increased from 4 to 14 years. The total basal area of individuals ≥ 1cm d.b.h. also increased with the age of abandonment. Overall, small individuals (< 10 cm dbh) contributed to more than half of the total basal area. Species diversity was the highest in the 9-year old stand followed by 14-and 4-year-old stands. We concluded that floristic composition of secondary forests recovers rapidly to the mature forest level compared to structural attributes, which is consistent with the general successional trajectories of tropical dry forest.
基金supported financially by the Education Department of Jiangxi Provincial(GJJ151141)National Natural Science Foundation of China(31660234)+1 种基金Jiangxi Province Department of Science and Technology(20161BBH80049)the Outstanding Young Scholar of Jiangxi Science and Technology Innovation(20192BCBL23016)。
文摘Forest recovery plays a critical role in regulating eco-hydrological processes in forested watersheds.However,characteristics of the intra-annual runoff variation associated with different forest recovery patterns remain poorly understood.In this study,three forest change periods were identified,the baseline period(1961-1985),reforestation period(1986-2000)and fruit tree planting period(2001-2016).We selected the magnitude of seasonal runoff(wet and dry seasons)and distribution characteristics,i.e.,non-uniformity coefficient(C_(v)),complete accommodation coefficient(C_(r)),concentration ratio(C_(n)),concentration period(C_(d)),absolute variation ratio(ΔR)and relative variation ratio(C_(max)).The pair-wise approach evaluated the intra-annual runoff variation characteristics between forest change periods.Results indicate that reforestation decreased wet season runoff and increased dry season runoff.In contrast,fruit tree planting increased wet season runoff and had no significant effect on dry season runoff.For intra-annual runoff distribution characteristics,reforestation significantly reduced the C_(v),C_(r),C_(n)and C_(max).Distribution of the intra-annual runoff in the fruit tree planting period was not significantly different from the baseline.We concluded that reforestation reduced the occurance of extreme water conditions in wet and dry seasons and effectively increased the stability of the intra-annual runoff.In contrast,fruit tree planting increased instability and fluctuation of the intra-annual runoff after reforestation.The characteristics of the intra-annual runoff to fruit tree planting was similar to those of the baseline.Therefore,adopting fruit tree planting practices to regulate intra-annual runoff characteristics may not be a practical approach,and impacts of different reforestation practices should be ascertained in our study region.The implications of this study should guide regional land-water management,and this study adds to the understanding of the impacts gained in forest cover on hydrology.
基金funded by CONACYT and DGAPA within the sabbatical abroad program for the consolidation of research groups“Dynamics of deforestation,forest degradation and recovery in the Monarch Butterfly Biosphere Reserve”。
文摘Analysis of the change in forest cover is important to determine stand dynamics and the processes involved in disturbance and recovery.Forests of the core zone of the Monarch Butterfly Biosphere Reserve were studied using photo interpretation techniques,considering biennial changes between 1999 and 2013 and changes over the whole period of study 1999–2013.Error matrices were elaborated to determine the processes of change involved in both recovery and disturbance.The biennial changes for the whole period amounted to 2274 ha;343 ha accounted as degraded in more than one biennial period.The total changes in forest cover between 1999 and 2013 involved 4902 ha,out of which,2912 ha were affected by disturbance,and 1990 ha were recovered.For density and 2013 vegetation cover maps,the overall accuracy was 95.6%and 90.2%,respectively.By combining both maps,gradual processes were revealed that were not evident in separate analyses.This methodology is useful for the management and conservation of natural protected areas.
基金supported by National Natural Science Foundation of China (31600330)Guangdong Forestry Science and Technology Innovation Project (2015KJCX029)CFERN & BEIJING TECHNO SOLUTIONS Award Funds on excellent academic achievements
文摘Secondary forests account for a large amount of subtropical forest due to persistent anthropogenic disturbance in China.The interaction between vegetation and soil during recovery process is rather complex and dependent on forest conditions.Understanding how vegetation and soil properties changes and how their relationship develops in secondary forests is key to effective forest restoration and management.Here we explored the patterns of vegetation and soil properties as well as their correlations during forest recovery process in a subtropical forest in south China.Plots of three forest types,i.e.,broadleaf-conifermixedforest,broadleaved forest and old growth stand,were established to represent the recovery stages.The results showed that diversity patterns in the tree,shrub and herb layers were different:in the tree layer the species diversity peaked at the intermediate stage,while in the understory layers it decreased chronologically.Most of the soil factors showed an increasing trend,and different effects of soil factors were found for the three layers as well as for the two spatial scales.Together,our results suggested that vegetation and soil might be interdependent during the recovery course.Further studies are needed on exploring how vegetation interplays with soil at different scales and how nutrient limitations affects the vegetation development in a chronosequence.
基金This work was jointly supported by the National Natural Science Foundation of China(Grant Nos.31971577 and 31670552)the Biodiversity Investigation,Observation and Assessment Program sponsored by the Ministry of Ecology and Environment of China(2019-2023)+1 种基金the China Postdoctoral Science Foundation(No.2019M651842)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘Climate change,a recognized critical environmental issue,plays an important role in regulating the structure and function of forest ecosystems by altering forest disturbance and recovery regimes.This research focused on exploring the statistical relationships between meteorological and topographic variables and the recovery characteristics following disturbance of plantation forests in southern China.We used long-term Landsat images and the vegetation change tracker algorithm to map forest disturbance and recovery events in the study area from 1988 to 2016.Stepwise multiple linear regression(MLR),random forest(RF)regression,and support vector machine(SVM)regression were used in conjunction with climate variables and topographic factors to model short-term forest recovery using the normalized difference vegetation index(NDVI).The results demonstrated that the regenerating forests were sensitive to the variation in temperature.The fitted results suggested that the relationship between the NDVI values of the forest areas and the post-disturbance climatic and topographic factors differed in regression algorithms.The RF regression yielded the best performance with an R2 value of 0.7348 for the validation accuracy.This indicated that slope and temperature,especially high temperatures,had substantial effects on post-disturbance vegetation recovery in southern China.For other mid-subtropical monsoon regions with intense light and heat and abundant rainfall,the information will also contribute to appropriate decisions for forest managers on forest recovery measures.Additionally,it is essential to explore the relationships between forest recovery and climate change of different vegetation types or species for more accurate and targeted forest recovery strategies.
文摘Montane forest ecosystems support biodiversity and provide varied ecosystem services to adjacent and downstream human communities. However, human-induced disturbances are common in many of these ecosystems, threatening their capacity to sustain their functions. This study assessed the status of woody vegetation and livestock use of a Kenyan montane forest 10 years after government-sanctioned cessation of human encroachment. The findings can inform suitable interventions that support recovery of abandoned forest settlements subjected to continuous anthropogenic disturbances. Selected woody vegetation attributes and livestock disturbance indicators were assessed across three human-driven disturbance regimes (light, moderate and heavy) using stratified-systematic sampling technique. Data on the extent of community dependence on forest grazing were collected from 381 randomly selected forest adjacent households using semi-structured questionnaires. Information on the palatability of plants to livestock was obtained from Focus Group Discussions. Vegetation data were analyzed using linear mixed models, while descriptive analysis was applied on household survey data. A total of 33 woody plant species belonging to 22 families were identified, out of which 55% were perceived to be unpalatable to livestock. Species richness, species diversity, stem density and basal areas declined significantly with increasing levels of disturbance. Specifically, these attributes were 59% - 98% lower in heavily disturbed sites than in moderately and lightly disturbed sites. A vast majority (88%) of the sampled households grazed their livestock in the forest throughout the year. Evidence from this study indicates that intense past and ongoing anthropogenic disturbances caused significant negative effects on the forest vegetation condition, and lowered its capacity to recover. Forest managers should prioritize minimizing recurrent anthropogenic disturbances as the forest recovers to ensure successful succession and sustainable provision of ecosystem services.
基金Under the auspices of the‘948’Project sponsored by the State Forestry Administration(SFA)of China(No.2014-4-25)National Natural Science Foundation of China(No.31670552,31270587)Doctorate Fellowship Foundation of Nanjing Forestry University,the PAPD(Priority Academic Program Development)of Jiangsu Provincial Universities,Graduate Research and Innovation Projects in Jiangsu Province(No.KYLX15_0908)
文摘Forest disturbance plays a vital role in modulating carbon storage,biodiversity and climate change.Yearly Landsat imagery from 1986 to 2015 of a typical plantation region in the northern Guangdong province of southern China was used as a case study.A Landsat time series stack(LTSS) was fed to the vegetation change tracker model(VCT) to map long-term changes in plantation forests' disturbance and recovery,followed by an intensive validation and a continuous 27-yr change analysis on disturbance locations,magnitudes and rates of plantations' disturbance and recovery.And the validation results of the disturbance year maps derived from five randomly identified sample plots with 25 km^2 located at the four corners and the center of the scene showed the majority of the spatial agreement measures ranged from 60% to 83%.A confusion matrix summary of the accuracy measures for all four validation sites in Fogang County showed that the disturbance year maps had an overall accuracy estimate of 71.70%.Forest disturbance rates' change trend was characterized by a decline first,followed by an increase,then giving way to a decline again.An undulated and gentle decreasing trend of disturbance rates from the highest value of 3.95% to the lowest value of 0.76% occurred between 1988 and 2001,disturbance rate of 4.51% in 1994 was a notable anomaly,while after 2001 there was a sharp ascending change,forest disturbance rate spiked in 2007(5.84%).After that,there was a significant decreasing trend up to the lowest value of 1.96% in 2011 and a slight ascending trend from 2011 to 2015(2.59%).Two obvious spikes in post-disturbance recovery rates occurred in 1995(0.26%) and 2008(0.41%).Overall,forest recovery rates were lower than forest disturbance rates.Moreover,forest disturbance and recovery detection based on VCT and the Landsat-based detections of trends in disturbance and recovery(LandT rendr) algorithms in Fogang County have been conducted,with LandT rendr finding mostly much more disturbance than VCT.Overall,disturbances and recoveries in northern Guangdong were triggered mostly by timber needs,policies and decisions of the local governments.This study highlights that a better understanding about plantations' changes would provide a critical foundation for local forest management decisions in the southern China.
基金sponsored by the "State Key Laboratory of Resources and Environmental Information System" and the "Fundamental Research Funds for the Central Universities" (No. 11SSXT134)
文摘Monitoring forest disturbances is important for understanding changes in ecosystems. The 1986 Typhoon Vera was a serious disturbance that severely impacted the forest ecosystems of Changbai Mountain National Nature Reserve. Although the typhoon disturbance occurred more than two decades ago, the effects of the typhoon still remain within the study area. Few studies have focused on mapping and assessing disturbances across broad spatial and temporal scales. For this study, we first generated a map of forest composition prior to the typhoon disturbance, which served as a baseline data for the extraction of disturbed area. Then, the Disturbance Index(DI) method was tested for mapping the extent and magnitude of disturbance in the study area by applying a Tasseled Cap transformation to the Landsat imagery. The Landsatbased DI method estimated that an area of 13,764.78 ha of forest was disturbed by the typhoon. Based on visual assessments, these results correspond closely with the reference map derived from ground surveys. These results also revealed the influence of local topographic features on the distribution of windthrow areas. Windthrow areas were more pronounced inareas with elevations ranging from 1,000 to 2,000 m, slopes of less than 10 degrees, and southwestern to northwestern aspects. In addition, the relatively long(25 years) post-typhoon recovery period assessed by this study provided a more comprehensive analysis of the dynamics of forest recovery processes over time. Windthrow areas did not recover immediately after the typhoon, likely due to forest management practices enacted at the time. So far, forest recovery has proceeded more rapidly at elevations below 1,400 m, particularly on western slopes within the study area. Finally, a time series of DI values within the study period suggests a secondary disturbance may have occurred between 2000 and 2001.
文摘Understanding how soil fertility changes due to environmental conditions and stand-age-dependent forest attributes is important for local-scale forest restoration.We evaluated the effects of stand-age-dependent forest attributes(plant community composition and litter stock)on soil and technosol fertility across two second-growth Atlantic forests(SGF)after the deposition of mining tailings in Mariana,southeastern Brazil.We hypothesized that technosol fertility in the SGF tailings is positively affected by plant community composition variability,stand age,and litter stock.We used total exchangeable bases and organic matter as fertility indicators for technosol and soil,and species composition and litter stock as stand-age-dependent forest attributes.Our results showed significant differences in the stand-age-dependent forest attributes and soil chemical properties between the two forest patches(SGF tailing and SGF non-tailing)evaluated.Thus,there was a marked gradient of litter storage and fertility between soil and technosol that can be important forest recovery indicators for the affected plant communities.Furthermore,according to the tested models,we corroborated the hypothesis that technosol fertility is positively affected by stand age,plant community composition variability,and litter stock,which may contribute considerably to forest recovery on tailings.Our results demonstrate that the fertility predictors analyzed to explain the forest recovery on tailings can also be considered as ecological indicators for assessing forest restoration in areas impacted by mining tailings in Mariana.
文摘We investigated the effects of grazing on natural regeneration, quantity, and diversity of woody species and dominant herb species in Kheyroud forest in northern Iran. We sampled vegetation in 5m2 plots in custom units, which are demarcated resource areas traditionally used by local livestock producers. The authors quantified number of species, height of seedlings, and diameter of seedlings. Height classes were 0-30 cm, 30-130 cm, and 〉130 cm, and diameter classes were 0-2.5 cm, 2.5-5 cm and 5-7.5 cm. The density of seedlings declined with distance from corral until reaching the custom unit boundary. Most seedlings had diameters of 0-2.5 cm and heights of 0-30 cm. Predominant species, Carpinus betulus and Acer capadocicum, were in plots near the centers of custom units, Fagus orientalis, Acer velutinum, Quercus castanifolia species were dominant in plots near the custom unit boundary. Plant species such as Oplismenus undulatifolius, Euphorbia amygdaloides, Rubusfrutieos and Pteridium aquilinum were dominant in plots nearer to forest corral. Healthy seedlings were more numerous in plots nearest the corral, while defective and deformed seedlings were more abundant away from the corral. We conclude that grazing had negative effects on the quantity and quality of vegetative regeneration. Continuation of overgrazing will not only endanger the sustainability of forest ecosystems, but also will increase the challenge of sustainable forest management.
基金This project was funded by the Research Experience for Undergraduates programme at El Verde Field Station,University of Puerto Rico(NSF-DBI-1559679,Alonso Ramírez,Principal Investigator).
文摘Aims Human land use such as agriculture and logging can have cascad-ing effects on the environment and severely influence forest eco-systems by altering structure,species composition and community processes.These activities may have long-term consequences,which impact forest recovery.We investigated the legacy of his-torical anthropogenic land use on the current reproductive effort(RE)and success of the understory,myco-heterotrophic orchid,Wullschlaegelia calcarata in Puerto Rico’s tropical rain forest after 80 years of forest recovery.Methods Our study site was the 16-ha Luquillo Forest Dynamics Plot in the Luquillo Experimental Forest.We used six 10 m×500 m transect lines that spanned areas with differing levels of historic canopy coverage which are correlated with land use history.We recorded the abundance of W.calcarata plants and measured shoot height,number of flowers,fruit set for all plants and seed set from the most mature,undehisced fruit on a random subset of plants measured.We sought to determine whether or not there is a legacy of land use history on the RE and success of W.calcarata.Of the varying degrees of historic disturbance,we predicted that RE and success would be highest in minimally disturbed old-growth forest,and that soil type differences would be insufficient to affect RE or success.Important Findings We found 1607 plants of W.calcarata,and only one was detected in the most historically disturbed area of the forest.The orchids were most abundant in the two least historically disturbed sites.However,the prevailing trend in all measures of RE is in the opposite direction with greater RE in the forest plots with intermediate levels of histori-cal disturbance.Furthermore,the best model(as a function of AICc and weights)to predict RE is a combination of soil type and cover class.Nevertheless,our measures of reproductive success(fruit and seed set)were best in the least historically disturbed sites and were not associated with soil type.Thus,the best sites for growth are not always the same as those for abundance and reproduction,and after>80 years of recovery,components of the rainforest community have not fully recovered.
