Awareness of the adverse ecological effects of road and other large construction projects has resulted in a rapidly growing demand to quantitatively predict and evaluate the effects on gene flow among plants and anima...Awareness of the adverse ecological effects of road and other large construction projects has resulted in a rapidly growing demand to quantitatively predict and evaluate the effects on gene flow among plants and animals in natural habitats.In this study,we evaluated the effects of different road construction scenarios on animal species movement by using the methods of ecological landscape connectivity in the typical regions of Yunnan Province,China.The results showed landscape connectivity levels(Probability of Connectivity(PC))decreased after road construction and species with lower dispersal abilities were more affected to the subsequent habitat fragmentation.First level roads affected landscape connectivity most significantly.At a distance of 100 m,the PC index decreased more than 50%.Further analysis suggested that the use of landscape connectivity to assess landscape processes revealed the adverse effects on the species movement more effectively compared with the traditional landscape pattern analysis.In addition,we conducted a graph theory and a least-cost modeling discussion,it is obvious that they are powerful tools to represent and analyze landscape networks with respect to related species movement.Network analysis offers a quantitative and simple but effective tool for ecological process assessment and biological conservation on large scales.展开更多
A study was conducted to examine the natural regeneration of three dry forest species, Lysiloma divaricatum （Jacq.）, Tabebuia ochracea （Cham.） and Lonchocarpus minimiflorus （Donn. Sin.） over a three-year period ...A study was conducted to examine the natural regeneration of three dry forest species, Lysiloma divaricatum （Jacq.）, Tabebuia ochracea （Cham.） and Lonchocarpus minimiflorus （Donn. Sin.） over a three-year period and to analyze heterogeneity of regeneration in relationship to topographic slope and incidence of light in Chacocente Wildlife Reserve in Nicaragua. Permanent sample plots were established in 2001, and all individuals with height as low as 10 cm and diameter as large as 10 cm were recorded for three consecutive years from 2001 to 2003. The results show that the density of naturally regenerated individuals varied significantly among species, as well as over time. L. minimiflorus and T. ochracea had higher densities compared with L. divaricatum, and the net change in population density was slightly positive for T. ochracea only. Regeneration was more abundant in the gentle and steep slopes under partial exposure of the crown to sunlight, thus resulting in aggregated pattern of distribution, especially for L. minimiflorus and T. ochracea. We concluded that natural regeneration alone is not sufficient to maintain the desired number of stocks of these species, and an immediate restoration measure should be taken to assist the natural regeneration process.展开更多
An exploratory survey was conducted on the uses and role of invasive alien species(IAS) to local livelihoods in the Rema-Kalenga Wildlife Sanctuary in the northeastern hilly region of Bangladesh.Vegetation was sampled...An exploratory survey was conducted on the uses and role of invasive alien species(IAS) to local livelihoods in the Rema-Kalenga Wildlife Sanctuary in the northeastern hilly region of Bangladesh.Vegetation was sampled in 50 quadrates,each 10 m×10 m,and 25 line transects,each 50 m×20 m,through a combination of random and systematic sampling.Group discussions were also arranged with fifty local inhabitants(17 % of the total inhabitants) to learn the various uses of IAS.A total of 17 alien plant species belonging to 10 different families,of which Leguminosae constitutes the highest number(5 species),include tree(53%) followed by herb(12%),shrub(12%) and others(weed,climber and palm).The majority of the identified species were found to be used for fuel,followed by timber production,medicinal or curative uses,fodder,and many others.In addition to providing various forest products,alien tree species planted in forest plantation help provide many vital ecosystem services such as soil amelioration through nitrogen fixation.It is true that the alien species have some negative impacts on local ecosystems,and not all of them are harmful.Therefore,a national programme must be initiated to distinguish the harmful from the harmless species and to identify the uses and impacts of the former and latter.展开更多
Cryopreservation of spermatozoa is a strategy that has been used to conserve the sperm of animal species and animal strains that are valuable for biomedical research. A simple method for preserving spermatozoa after a...Cryopreservation of spermatozoa is a strategy that has been used to conserve the sperm of animal species and animal strains that are valuable for biomedical research. A simple method for preserving spermatozoa after application of intracytoplasmic sperm injection （ICSI） is much needed. It has been shown previously that spermatozoa frozen at -20~C can activate oocytes and support full-term embryo development. However, epigenetic reprogramming could be affected by the environment and by the in vitro manipulation of gametes. Here, we investigated embryo epigenetic reprogramming including DNA methylation and histone modification, in embryos derived from sperm preserved at -20~C without cryoprotectants. The results showed that alt- hough both fertilization and embryo developmental competence were decreased, the dynamic epigenetic reprogramming of embryos derived from frozen sperm was similar to the reprogramrning of embryos derived from fresh sperm. The results re- ported in this study indicate that sperm frozen without cryoprotectant is epigenetically safe for ICSI.展开更多
Urbanization and exotic species are major threats to the conservation of forest-dependent wildlife species. Some emblematic species, indicators of habitat quality for the conservation of other spe- cies, might success...Urbanization and exotic species are major threats to the conservation of forest-dependent wildlife species. Some emblematic species, indicators of habitat quality for the conservation of other spe- cies, might successfully be reintroduced within cities when habitat restoration and pest manage- ment programs are combined. We studied the landscape resource selection of juvenile kaka Nestor meridionalis tracked with Global Positioning System （GPS） units and released into the predator- free reserve of Zealandia in Wellington city, New Zealand. Kaka moved beyond the predator exclu- sion fence into urban suburbs. The home range size and areas of high use estimated using local convex hull （a-LoCoH） ranged from 20 to 240 ha and 2 to 21 ha, respectively. Using resource selec- tion functions and model selection we found that native forest patches and urban areas close to the reserve were selected by kaka to establish their home ranges. At a lower scale of selection （i.e., se- lection of habitats within home ranges）, kaka selected the same habitat, but not necessarily those close to the reserve. Native forest patches throughout the city can facilitate the dispersal of individ- uals, while the reserve provides protection and opportunities for supplementary feeding. Urban areas might have been selected due to the placement of feeders in private backyards. Survival of forest-dwelling species in cities requires careful urban planning and management to provide the necessary habitat patches, refugia, and food sources.展开更多
基金Under the auspices of Nonprofit Environment Protection Specific Project of China(No.201209029-4)
文摘Awareness of the adverse ecological effects of road and other large construction projects has resulted in a rapidly growing demand to quantitatively predict and evaluate the effects on gene flow among plants and animals in natural habitats.In this study,we evaluated the effects of different road construction scenarios on animal species movement by using the methods of ecological landscape connectivity in the typical regions of Yunnan Province,China.The results showed landscape connectivity levels(Probability of Connectivity(PC))decreased after road construction and species with lower dispersal abilities were more affected to the subsequent habitat fragmentation.First level roads affected landscape connectivity most significantly.At a distance of 100 m,the PC index decreased more than 50%.Further analysis suggested that the use of landscape connectivity to assess landscape processes revealed the adverse effects on the species movement more effectively compared with the traditional landscape pattern analysis.In addition,we conducted a graph theory and a least-cost modeling discussion,it is obvious that they are powerful tools to represent and analyze landscape networks with respect to related species movement.Network analysis offers a quantitative and simple but effective tool for ecological process assessment and biological conservation on large scales.
基金supported by the Swedish International Development Agency (Sida)
文摘A study was conducted to examine the natural regeneration of three dry forest species, Lysiloma divaricatum （Jacq.）, Tabebuia ochracea （Cham.） and Lonchocarpus minimiflorus （Donn. Sin.） over a three-year period and to analyze heterogeneity of regeneration in relationship to topographic slope and incidence of light in Chacocente Wildlife Reserve in Nicaragua. Permanent sample plots were established in 2001, and all individuals with height as low as 10 cm and diameter as large as 10 cm were recorded for three consecutive years from 2001 to 2003. The results show that the density of naturally regenerated individuals varied significantly among species, as well as over time. L. minimiflorus and T. ochracea had higher densities compared with L. divaricatum, and the net change in population density was slightly positive for T. ochracea only. Regeneration was more abundant in the gentle and steep slopes under partial exposure of the crown to sunlight, thus resulting in aggregated pattern of distribution, especially for L. minimiflorus and T. ochracea. We concluded that natural regeneration alone is not sufficient to maintain the desired number of stocks of these species, and an immediate restoration measure should be taken to assist the natural regeneration process.
文摘An exploratory survey was conducted on the uses and role of invasive alien species(IAS) to local livelihoods in the Rema-Kalenga Wildlife Sanctuary in the northeastern hilly region of Bangladesh.Vegetation was sampled in 50 quadrates,each 10 m×10 m,and 25 line transects,each 50 m×20 m,through a combination of random and systematic sampling.Group discussions were also arranged with fifty local inhabitants(17 % of the total inhabitants) to learn the various uses of IAS.A total of 17 alien plant species belonging to 10 different families,of which Leguminosae constitutes the highest number(5 species),include tree(53%) followed by herb(12%),shrub(12%) and others(weed,climber and palm).The majority of the identified species were found to be used for fuel,followed by timber production,medicinal or curative uses,fodder,and many others.In addition to providing various forest products,alien tree species planted in forest plantation help provide many vital ecosystem services such as soil amelioration through nitrogen fixation.It is true that the alien species have some negative impacts on local ecosystems,and not all of them are harmful.Therefore,a national programme must be initiated to distinguish the harmful from the harmless species and to identify the uses and impacts of the former and latter.
基金supported by the National Basic Research Program of China (Grant No. 2011CB944501)
文摘Cryopreservation of spermatozoa is a strategy that has been used to conserve the sperm of animal species and animal strains that are valuable for biomedical research. A simple method for preserving spermatozoa after application of intracytoplasmic sperm injection （ICSI） is much needed. It has been shown previously that spermatozoa frozen at -20~C can activate oocytes and support full-term embryo development. However, epigenetic reprogramming could be affected by the environment and by the in vitro manipulation of gametes. Here, we investigated embryo epigenetic reprogramming including DNA methylation and histone modification, in embryos derived from sperm preserved at -20~C without cryoprotectants. The results showed that alt- hough both fertilization and embryo developmental competence were decreased, the dynamic epigenetic reprogramming of embryos derived from frozen sperm was similar to the reprogramrning of embryos derived from fresh sperm. The results re- ported in this study indicate that sperm frozen without cryoprotectant is epigenetically safe for ICSI.
文摘Urbanization and exotic species are major threats to the conservation of forest-dependent wildlife species. Some emblematic species, indicators of habitat quality for the conservation of other spe- cies, might successfully be reintroduced within cities when habitat restoration and pest manage- ment programs are combined. We studied the landscape resource selection of juvenile kaka Nestor meridionalis tracked with Global Positioning System （GPS） units and released into the predator- free reserve of Zealandia in Wellington city, New Zealand. Kaka moved beyond the predator exclu- sion fence into urban suburbs. The home range size and areas of high use estimated using local convex hull （a-LoCoH） ranged from 20 to 240 ha and 2 to 21 ha, respectively. Using resource selec- tion functions and model selection we found that native forest patches and urban areas close to the reserve were selected by kaka to establish their home ranges. At a lower scale of selection （i.e., se- lection of habitats within home ranges）, kaka selected the same habitat, but not necessarily those close to the reserve. Native forest patches throughout the city can facilitate the dispersal of individ- uals, while the reserve provides protection and opportunities for supplementary feeding. Urban areas might have been selected due to the placement of feeders in private backyards. Survival of forest-dwelling species in cities requires careful urban planning and management to provide the necessary habitat patches, refugia, and food sources.
