National assessment of the evolution of forest fragmentation in Mexico

This paper presents assessments of the fragmentation of the temperate and tropical forests in Mexico at the national level for two dates 1993 and 2002.The study was based on land use and vegetation cover data sets scale 1：250,000.Two broad forest types（Temperate Forests and Tropical Forests） and five more specific forest types（Broadleaf Forests,and Coniferous Forests;Tropical Dry Deciduous Forests,Tropical Sub-evergreen Forests,and Tropical Evergreen Forests） were defined to conduct the analyses.FragStats 3.3 was used to estimate nine metrics of the spatial pattern of the forests for each forest type and date considered.The results indicate that the land cover transitions that have occurred between 1993 and 2002 have resulted in more isolated forest patches with simpler shapes in both the Temperate and Tropical Forests.The remaining Tropical Forest patches have become smaller and more numerous.In contrast,the remaining Temperate Forest patches are fewer and on average larger.Of the more specific forest types defined in this study,the Broadleaf Forests have the highest indicators of fragmentation.However these forests are usually embedded or adjacent to Coniferous Forests.Of more concern for conservation purposes are the high values of fragmentation metrics found for the Tropical Evergreen Forests and Tropical Dry Deciduous Forests,because these forest types are usually surrounded by non-forest land covers or anthropogenic land uses.

Effects of forest fragmentation on nocturnal Asian birds:A case study from Xishuangbanna,China

Owls have the potential to be keystone species for conservation in fragmented landscapes, as the absence of these predators could profoundly change community structure. Yet few studies have examined how whole communities of owls respond to fragmentation, especially in the tropics. When evaluating the effect of factors related to fragmentation, such as fragment area and distance to the edge, on these birds, it is also important in heterogeneous landscapes to ask how ＇location factors＇ such as the topography, vegetation and soil of the fragment predict their persistence. In Xishuangbanna, southwest China, we established 43 transects （200 mx60 m） within 20 forest fragments to sample nocturnal birds, both visually and aurally. We used a multimodel inference approach to identify the factors that influence owl species richness, and generalized linear mixed models to predict the occurrence probabilities of each species. We found that fragmentation factors dominated location factors, with larger fragments having more species, and four of eight species were significantly more likely to occur in large fragments. Given the potential importance of these birds on regulating small mammal and other animal populations, and thus indirectly affecting seed dispersal, we suggest further protection of large f ragments and programs to increase their connectivity to the remaining smaller fragments.

Characterizing changes in land cover and forest fragmentation from multitemporal Landsat observations(1993-2018)in the Dhorpatan Hunting Reserve,Nepal

Natural forces and anthropogenic activities greatly alter land cover,deteriorate or alleviate forest fragmentation and affect biodiversity.Thus land cover and forest fragmentation dynamics have become a focus of concern for natural resource management agencies and biodiversity conservation communities.However,there are few land cover datasets and forest fragmentation information available for the Dhorpatan Hunting Reserve(DHR)of Nepal to develop targeted biodiversity conservation plans.In this study,these gaps were filled by characterizing land cover and forest fragmentation trends in the DHR.Using five Landsat images between 1993 and 2018,a support vector machine algorithm was applied to classify six land cover classes:forest,grasslands,barren lands,agricultural and built-up areas,water bodies,and snow and glaciers.Subsequently,two landscape process models and four landscape metrics were used to depict the forest fragmentation situations.Results showed that forest cover increased from 39.4%in 1993 to 39.8%in 2018.Conversely,grasslands decreased from 38.2%in 1993 to 36.9%in 2018.The forest shrinkage was responsible for forest loss during the period,suggesting that the loss of forest cover reduced the connectivity between forest and nonforested areas.Expansion was the dominant component of the forest restoration process,implying that it avoided the occurrence of isolated forests.The maximum value of edge density and perimeter area fractal dimension metrics and the minimum value of aggregation index were observed in 2011,revealing that forests in this year were most fragmented.These specific observations from the current analysis can help local authorities and local communities,who are highly dependent on forest resources,to better develop local forest management and biodiversity conservation plans.

Deforestation and forest fragmentation in the highlands of Eastern Ghats,India

Tropical forest cover change along with increasing fragmentation has detrimental effects on the global biodiversity.In the current study change in both forest cover and fragmentation of Koraput district have been assessed in the past three decades(1987-2017)and future decade(2017-2027),which has been modelled using logistic regression showing a gradual decrease in the forest cover and increase in fragmentation.The long term deforestation rates from 1987 to 2017(current period)and from 1987 to 2027(predicted period)were found to be-0.018 and-0.012,respectively.Out of the total geographical area,2027 number of grids(1 km^(2))out of 8856 grids were found to have shown extinction of forest in the study period.The conversion of forested lands into other land uses has been one of the major causes of deforestation in Koraput,especially because of the increasing mining activities and establishment of three major industries namely National Aluminium Company(NALCO),Damanjodi,Hindustan Aeronautics Limited(HAL),Sunabeda and Ballarpur Industries Limited(BILT).The forest fragmentation reveals a negative trend,recording highest conversion from large core fragments to edge(191.33 km2)and the predicted period has also shown the same trend of negative change,which poses serious danger to the structure of the forests.Out of all the landscape matrices calculated,number of patches will increase to 214 in 2027 from 93 in 1987.In the test between geographically weighted regression(GWR)and ordinary least square regression(OLS),GWR was the better fit model for drawing a spatial relationship between forest cover and fragmentation changes.The study confirmed that the forest cover change has impacted the forest fragmentation in the study area.The programmes like REDD+should be implemented along with the experiences of Community Forest Management and the joint forest management should be intensified at community level in order to develop better management practices to conserve habitats in biodiversity rich areas.

A township-level assessment of forest fragmentation using morphological spatial pattern analysis in Qujing,Yunnan Province,China

Forest fragmentation is an integral part of global change.Understanding forest fragmentation patterns and dynamics are of great significance for maintaining ecosystem stability.There are great differences in the interference of natural and human factors on forests in different towns of mountainous cities,and the characteristics of forest fragmentation are also obviously different.Forest fragmentation has been broadly studied,yet,it remains poorly understood at the township-scale within mountainous cities.In this study,the spatial form of forest landscape and forest fragmentation modes of towns were examined in Qujing City,Yunnan Province,China for the years of 2006 and 2016,relying heavily on the morphological spatial pattern analysis(MSPA)and K-means clustering algorithm.Results in 2016 showed that the forest landscape morphology of Qujing could be divided into seven classes:core,perforation,islet,bridge,edge,branch and ring;with landscape areas of 41.94%,1.22%,7.04%,11.12%,23.26%,11.74%and 3.68%respectively.Compared with 2006,the changes of landscape area were 1.71%,0.02%,0.30%,1.65%,0.20%,0.19%and 0.05%respectively.The townships in Qujing varied significantly in their landscape fragmentation patterns,and these patterns were spatially dependent.Different forest landscape forms have positive spatial correlations and differences.The forest fragmentation modes of towns can be divided into four types:Low anthropogenic towns,high anthropogenic towns,complex terrain towns and gentle terrain towns.Different ways of human activities play a decisive role in forest landscape fragmentation.The expansion of construction land and agricultural land intensifies forest fragmentation;however,man-made orderly and planned ecological restoration will greatly improve the forest coverage and improve the spatial form of urban forest landscape.

National assessment of the fragmentation,accessibility and anthropogenic pressure on the forests in Mexico

Forest managers and policy makers increasingly demand to have access to estimates of forest fragmentation, human accessibility to forest areas and levels of anthropogenic pressure on the remaining forests to integrate them into monitoring systems, management and conservation plans. Forest fragmentation is defined as the breaking up of a forest unit, where the number of patches and the amount of expose edge increase while the amount of core area decreases. Forest fragmentation studies in Mexico have been limited to local or regional levels and have concen- trated only on specific forest types. This paper presents an assessment of the fragmentation of all forest types at the national level, their effective proximity to anthropogenic influences, and the development of an indica- tor of anthropogenic pressure on the forests areas. Broadleaf forests, tropical evergreen forests and tropical dry deciduous forests show the greatest fragmentation. Almost half （47%） of the tropical forests are in close effective proximity to anthropogenic influences and only 12% of their area can be considered isolated from anthropogenic influences. The values for the temperate forests are 23% and 29% respectively. Anthro- pogenic pressure in the immediate vicinity of anthropogenic activities is much higher in the tropical forests （75 in a scale 0-100） than in the tem- perate forests （30）. When considering these results jointly, the tropical forests, and more specifically, the tropical evergreen forests and tropical dry deciduous forests are under the greatest pressure and risks of degra- dation.

Forest landscape and its ecological quality:A stepwise spatiotemporal evaluation through patch-matrix model in Jhargram District,West Bengal State,India

Landscape conversion becomes a continuous process in a natural landscape for any strategic development.In a forest landscape mosaic,the conversion from non-forest land to forest land implies a constructive approach.Various bio-geographic processes are enriched and developed when the land was converted to forest land in a given landscape matrix.The present study evaluated how the increased forest cover improves the ecological quality of forest in Jhargram District of West Bengal State,India,from 1985 to 2015.The quality of forests includes dominance,fragmentation and connectivity,which are the basis ecological indicators of habitat structure.To address this issue,we extracted forest cover maps of 1985 and 2015 from land use/land cover classification.A grid framework was overlaid on these forest cover maps for patch-matrix model analysis.Reliable landscape ecological indices were used for the measurements of forest landscape quality in 1985 and 2015.Then a simple linear regression model was used to compare the results.Temporally,forest cover increased in Jhargram District from 1985 to 2015.The comparison of measurement indices depicts that although only a small amount of land was changed into forest land in the study area,this small change has greatly improved the structural compositional quality of the forest land.Compared with 1985,the forest land area increased by about 6930.56 hm^(2) in 2015.This increased forest cover improved the basic landscape ecological characters,such as inter patch connectivity,forest core area,forest habitat dependence,forest habitat dominance and forest edge effect.As a result,the ecosystem function in Jhargram District has been improved,which again attracts wildlife and enriches biodiversity.

Monitoring of Residual Forest Ecosystems Dynamics in the Mono Biosphere Reserve (Southeast Togo)

The forest ecosystems of the Lacs 2 commune (South-East, Togo) are undergoing severe degradation, which has not yet been documented. This study is carried out in order to assess and quantify the spatio-temporal dynamics of residual forests and to identify the determinants of deforestation in South East Togo. The methodological approach is based on the use of historical aerial photographs from 1976 and drone images from 2019 in addition to field investigations. Several spatial structure indices were also calculated in order to quantify the fragmentation of classes and of the forest landscape. The results show that the forest landscape is changing. The classes of forests, plantations and palm groves show an annual rate of decline of 7.5%, 0.8% and 9.4% respectively while the classes of savannahs, agglomerations, surface water and swamps increased by 16.4%, 0.4%, 0.7% and 0.1%. The results also reveal a high fragmentation within the forest, plantation, surface water and swamp class and moderate fragmentation for the savannah and palm trees classes. At the landscape level, the savannah class is dominant by more than 70%, thus making the landscape little diversified from an ecological point of view. The main driver of deforestation in the study area remains shifting slash-and-burn agriculture. It is accentuated by the establishment of perennial oil palm crops, which has influenced the annual deforestation rate by 0.72%.

Impact of patch size on woody tree species richness and abundance in a tropical montane evergreen forest patches of south India

We examined the effects of forest patch size on woody tree species richness and abundance in tropical montane evergreen forest patches of the Nilgiri region,south India. We sampled woody trees(>1 cm dbh) from 21 forest patches in the upper Nilgiri hills(> 2000 m elevation) and recorded a total of 35,146 individuals of 61 species, 45 genera and 30 families. Species richness and abundance of sapling/shrubs(≥ 1 to < 10 cm dbh)increased significantly with increasing patch size, but the species richness and abundance of small, medium and larger trees(≥ 10 to < 30, ≥ 30 to < 60 and ≥ 60 cm dbh,respectively) did not. Overall, forest interior species richness and abundance increased significantly with increasing patch size but edge species richness did not. Species richness and abundance of shade-tolerant and shade-demanding tree species also increased with increasing patch size. The abundance of zoochory dispersed tree species was significantly related to increasing patch size, but those dispersed by autochory did not display any clear relationship between patch size and species richness or abundance.Our findings suggest that with increasing forest patch area,tree compositional patterns may be driven by species specific shade-tolerance adaptations and dispersal patterns.Differential responses in these traits by the plant community within the individual habitat zones of forest edge and interiors likely plays a major role in determining the inherent plant community and thus the subsequent ecological processes of forest patches, including their responses to increasing patch area.

Importance of microhabitat selection by birds for the early recruitment of endangered trees in a fragmented forest

Background:Remnant microhabitats are important for bird habitat selection and plant regeneration in the fragmented habitat.However,empirical information on the consequences of how microhabitat use by birds affects the early recruitment of plants is lacking.Methods:In this study,we evaluated whether microhabitat selection by the Black Bulbul(Hypsipetes leucocephalus)(J.F.Gmelin,1789)impacts the early recruitment of the endangered tree species,the Chinese Yew(Taxus chinensis(Pilger)Rehd),in a fragmented forest over a 4-year period(2011–2012,2018–2019).Results:Our results showed the main factors affecting H.leucocephalus microhabitat selection were distance to the nearest T.chinensis mature tree,herb cover and density,leaf litter cover,and vegetation type.Moreover,the results of logistic regression also highlighted the importance of elevation,distance to light gap and roads,tree cover in bird microhabitat selection.Furthermore,the seed emergence rate in microhabitats used by birds did not differ from the natural forest,which was related to five factors of bird microhabitat.The Random Forest model showed that seedling emergence rate was increased with leaf litter cover and distance to fallen dead trees,but decreased in relation to herb cover,slope,and elevation.Conclusion:Our results highlight the importance of remnant microhabitats in fragmented forests for sustaining forest ecology and optimal management.The contribution of microhabitats used by birds to plant recruitment provides insights into how frugivore species contribute to plant regeneration,which should be incorporated in future conservation and management practices of fragmented forests.

Patch isolation and shape predict plant functional diversity in a naturally fragmented forest

Aims It is known that taxonomic diversity can be predicted by the spatial configuration of the habitat,in particular by its area and degree of iso-lation.However,taxonomic diversity is a poor predictor of ecosystem functioning.While functional diversity is strongly linked to the func-tionality and stability of ecosystems,little is known about how changes in the spatial configuration of the habitat affect functional diversity.In this study,we evaluated whether the spatial configuration of forest patches predicts the functional diversity of plants in a fragmented forest.Methods Five functional leaf traits(leaf dry matter content,leaf punch force,specific leaf area,leaf size and leaf thickness)were measured for 23 dominant plant species in 20 forest patches in a naturally fragmented forest on the yucatan Peninsula.Abundance-weighted multivariate and individual trait metrics of functional diversity were calculated and cor-related with size,degree of isolation and the shape of forest patches.Important Findings Patch shape was negatively correlated with multivariate and individ-ual trait(leaf dry matter content and leaf size)metrics of functional diversity.Patch isolation measures were also negatively correlated with individual trait(leaf dry matter content,leaf punch force and leaf size)metrics of functional diversity.In other words,greater patch shape irregularity and isolation degree impoverish plant func-tional variability.This is the first report of the negative effects of patch shape irregularity and isolation on the functional diversity of plant communities in a forest that has been fragmented for a long time.

Effects of fragmentation on the seed predation and dispersal by rodents differ among species with different seed size

Fragmentation influences the population dynamics and community composition of vertebrate animals.Frag­mentation effects on rodent species in forests may,in turn,affect seed predation and dispersal of many plant species.Previous studies have usually addressed this question by monitoring a single species,and their results are contradictory.Very few studies have discussed the fragmentation effect on rodent-seed interaction among tree species with different seed sizes,which can significantly influence rodent foraging preference and seed fate.Given that fruiting periods for many coexisting plant species overlap,the changing foraging preference of ro­dents may substantially alter plant communities.In this study,we monitored the dispersal and predation by ro­dents of 9600 seeds,belonging to 4 Fagaceae species with great variation in seed size,in both the edge and inte­rior areas of 12 tropical forest fragments ranging in area from 6.3 to 13872.9 ha in Southwest China.The results showed that forest fragmentation altered the seed fates of all the species,but the intensity and even the direction of fragmentation effect differed between species with large versus small seeds.For the seeds harvested,frag­ment size showed negative effects in forest interiors but positive effects at edges for the 2 large-seeded species,but showed little effect for the 2 small-seeded species.For the seeds removed,negative effects of fragment size only existed among the small-seeded species.The different fragmentation effect on seed dispersal and predation among plant species may,in turn,translate into the composition differences of the regeneration of the whole fragmented forest.

Assessing genetic diversity and structure of fragmented populations of eastern white pine(Pinus strobus)and western white pine(P.monticola)for conservation management

Aims Many pine populations in Canada have fragmented distributions resulting from the effects of glaciations,overharvesting and white pine blister rust infections.Forest fragmentation can modify gene flow and reduce genetic diversity.Selective logging can reduce the density of trees,thereby altering mating patterns and increasing inbreeding.The hypothesis of the present study is that forest fragmentation will not increase inbreeding and will have no effect on genetic diversity parameters in the Canadian Pinus moniticola and P.strobus populations targeted because of(i)the long life span of the pine species,(ii)outbreeding and self-incompatibility of P.monticola and P.strobus and(iii)wind pollination resulting in high gene flow among populations.We studied the genetic diversity of P.strobus across its range in Canada,and we completed a detailed analysis of the genetic structure of P.monticola populations from western Canada using microsatellites genetic markers.Methods Seed samples from 10 P.monticola populations and 10 P.strobus populations were collected from western and eastern Canada,respectively.The mother trees included in seed lots were representative of each stand.Genomic DNA extracted from each sample was amplified with microsatellite primers.The intra-and interpopulation genetic diversity parameters were assessed using Popgene and Genepop softwares and the genetic distances among populations within each species using the PowerMarker software.

Extensive pollen immigration and no evidence of disrupted mating patterns or reproduction in a highly fragmented holm oak stand

Aims Forest fragmentation and reduced tree population densities can poten-tially have negative impacts on mating patterns,offspring genetic diversity and reproductive performance.the aim of the present study is to test these hypotheses comparing an extremely fragmented,low tree density(~0.02 trees/ha)holm oak(Quercus ilex l.)stand from Central spain with a nearby high tree density stand(~50 trees/ha).Methods We genotyped adult trees and seeds from the low-density stand(436 seeds from 15 families)and the high-density stand(404 seeds from 11 families)using nine microsatellite markers.With these data,we performed paternity analyses,determined pollen flow,mating patterns and pollen pool structure,and estimated progeny genetic diversity in both stands.We also studied seed set and production and performed a pollen supplementation experiment to determine whether reduced tree density has limited foreign pollen availability.Important Findings We have found extensive pollen immigration(>75%)into the low tree density stand and monte Carlo simulations revealed that pollen moves larger distances than expected from null models of random dispersal.mating patterns and differentiation of pollen pools were similar in the high-density stand and the low-density stand but we found higher inter-annual differentiation of pollen pools in the for-mer.Progeny genetic diversity and self-fertilization rates did not dif-fer between the low-density stand and the high-density stand.seed set rates were significantly lower in the low-density stand than in the high-density stand and experimental cross-pollen supplementation evidenced that foreign pollen availability is indeed a limiting factor in the former.However,seed crops did not differ between the low-density stand and the high-density stand,indicating that limitation of foreign pollen is not likely to be of great concern in terms of reduced seed production and potential recruitment.Poor forest regeneration due to other ecological and human factors is probably a more important threat for the persistence of fragmented and low tree density stands than reduced pollen flow and only extremely small and isolated tree populations would be expected to suffer severe loss of genetic diversity in the long term.

Potential impacts of UV exposure on lichen communities:a pilot study of Nothofagus dombeyi trunks in southernmost Chile

High-latitude terrestrial ecosystems face the triple threats of climate warming,increased exposure to UV arising from polar ozone depletion,and deforestation.Lichen communities of southernmost Chile are recognized for their high diversity,which includes nitrogen-fixing cyanolichens.Such lichens are common on forest trees,contribute nitrogen to forests,and are sensitive to exposure following deforestation(widespread in this region).In a pilot study of exposure effects on tree lichens,using nondestructive imaging methods,we compared lichen communities on trunks of isolated vs.forest tree trunks of southern Chilean beech(Nothofagus dombeyi,Nothofagaceae).We chose trees of similar diameter and trunk lean angle in conserved forest and nearby logged meadow on Navarino Island,XII Region Magallanes and Chilean Antarctica,Chile,within the annual southern ozone hole.Ninety-five percent of cyanolichen records,including Nephroma antarcticum,and 66%of records for other foliose lichens were from the forest,whereas pendulous usneoid lichens dominated N.dombeyi bark at the meadow site.Limitation of cyanolichen growth on isolated trees could affect ecosystem function in this poorly studied habitat.Possible factors contributing to strong community differences were increased light intensity,UV radiation,and wind stress,plus limited ability of lichens to colonize isolated trees in the logged meadow.UV radiation was likely an important stressor for some lichen species but not others.We recommend more extensive monitoring to pinpoint causes of differing lichen communities,and we encourage better protection of bark-dwelling lichens in southern hemisphere regions facing multiple threats.