Habitat loss and fragmentation are mainly associated with population decrease of endangered species and biodiversity loss. The habitat suitability maps of red-crowned crane （Grusjaponensis） in 1992, 1999 and 2006 we...Habitat loss and fragmentation are mainly associated with population decrease of endangered species and biodiversity loss. The habitat suitability maps of red-crowned crane （Grusjaponensis） in 1992, 1999 and 2006 were produced by using Ecological Niche Suitability Model （ENSM） in Yellow River Delta Nature Reserve （118°33′-119°20′E longitude, 37°35′-38°12′N latitude）, Shandong Province, China. Based on the habitat suitability maps, the causation and change law of habitat loss and fragmentation of red-crowned crane were analyzed by selecting a series of landscape pattern indices. Results showed that due to scarcities of fresh water sources, habitat suitability of red-crowned crane in 1999 was inferior to that in 1992 and 2006 no matter whether human disturbances existed or not. Besides, human disturbance activities, especially road disturbances, increased rapidly during the period of 1992-2006. This worsened the habitat loss and frag- mentation of red-crowned crane, and led to degrading habitat suitability of red-crowned crane in 2006, compared with that in 1992. In conclusion, fresh water sources and human disturbance activities are the two main factors that drive the habitat suitability change of red-crowned crane.展开更多
Plant invasion alters the fundamental structure and function of native ecosystems by affecting the biogeochemical pools and fluxes of materials and energy. Native(Suaeda salsa) and invasive(Spartina alterniflora) salt...Plant invasion alters the fundamental structure and function of native ecosystems by affecting the biogeochemical pools and fluxes of materials and energy. Native(Suaeda salsa) and invasive(Spartina alterniflora) salt marshes were selected to study the effects of Spartina alterniflora invasion on soil organic carbon(SOC) contents and stocks in the Yellow River Delta. Results showed that the SOC contents(g/kg) and stocks(kg/m^2) were significantly increased(P < 0.05) after Spartina alterniflora invasion of seven years, especially for the surface soil layer(0–20 cm). The SOC contents exhibited an even distribution along the soil profiles in native salt marshes, while the SOC contents were gradually decreased with depth after Spartina alterniflora invasion of seven years. The natural ln response ratios(Ln RR) were applied to identify the effects of short-term Spartina alterniflora invasion on the SOC stocks. We also found that Spartina alterniflora invasion might cause soil organic carbon losses in a short-term phase(2–4 years in this study) due to the negative Ln RR values, especially for 20–60 cm depth. And the SOCD in surface layer(0–20 cm) do not increase linearly with the invasive age. Spearman correlation analysis revealed that silt + clay content was exponentially related with SOC in surface layer(Adjusted R^2 = 0.43, P < 0.001), suggesting that soil texture could play a key role in SOC sequestration of coastal salt marshes.展开更多
Previous attempts to elucidate the drivers of speciation mechanisms and spatial distribution patterns of biodiversity in mountain regions have treated different floras within a single geological region as one flora,ig...Previous attempts to elucidate the drivers of speciation mechanisms and spatial distribution patterns of biodiversity in mountain regions have treated different floras within a single geological region as one flora,ignoring the potential contributions of high habitat/ecosystem heterogeneity.Furthermore,current conservation strategies largely focus on forest ecosystems and/or specific flagship species,ignoring marginal ecosystems,leaving species in these ecosystems at risk.Here,we compared the spatial patterns of biodiversity and the potential drivers of these patterns in the river valley and subnival ecosystems of the Hengduan Mountains region(HDM)in southwestern China.Specifically,we compared spatial patterns of diversity,endemism,and threatened species in these ecosystems based on both traditional measurements and recent phylogenetic approaches.We then examined how those patterns were related to environmental factors and human activity in these same regions.We found that the middle-southern HDM supports the highest diversity and endemism for the river valley and subnival ecosystems;however,the distribution patterns of neo-and paleo-endemism in these two ecosystems differ.Regression models indicate that habitat diversity and paleo-climatic fluctuation are important drivers of diversity and endemism for these two ecosystems.Temperature and precipitation,however,showed different influences on the spatial patterns in different ecosystems.Categorical analysis of neo-and paleoendemism(CANAPE)indicated that most endemism centers are not covered by current nature reserves.Moreover,the intensity of human activity is highest in the southern and southeastern HDM,which coincides with the distribution patterns of diversity,mixed-endemism and high-priority(and threatened)species.These findings suggest that different floras within a single geographic/floristic region respond differently to environmental factors and show different spatial phylogenetic patterns.We,therefore,recommend that future research into the drivers of biodiversity consider the contributions of various ecosystem types within a single geological region.This study also provides a theoretical basis for protecting habitat diversity.Our work confirms that current conservation efforts are insufficient to protect ecosystem diversity in the river valley and subnival ecosystems of the Hengduan Mountains.Therefore,we recommend the establishment of nature reserves in the regions identified in this study;furthermore,we strongly recommend improving current and establishing new management policies for biodiversity conservation in this region.展开更多
The glaciers in the Sanjiangyuan Nature Reserve of China(SNRC)are a significant water resource for the Yangtze,Yellow,and Mekong rivers.Based on Landsat Thematic Mapper(TM)/Operational Land Imager(OLI)images acquired ...The glaciers in the Sanjiangyuan Nature Reserve of China(SNRC)are a significant water resource for the Yangtze,Yellow,and Mekong rivers.Based on Landsat Thematic Mapper(TM)/Operational Land Imager(OLI)images acquired in 2000,2010,and 2018,the outlines of glaciers in the SNRC were obtained by combining band ratio method with manual interpretation.There were 1714 glaciers in the SNRC in 2018,with an area of 2331.15±54.84 km^(2),an ice volume of 188.90±6.41 km3,and an average length of 1475.4±15 m.During 2000-2018,the corresponding values of glaciers decreased by 69,271.95±132.06 km^(2),18.59±8.83 km3,and 84.75±34 m,respectively.Glaciers in the Yangtze River source area witnessed the largest area loss(-154.45 km^(2)),whereas glaciers in the Mekong River source area experienced the fastest area loss(-2.02%·a-1)and the maximum reduction of the average length(-125.82 m).Overall,the retreat of glaciers in the SNRC exhibited an accelerating trend.Especially,the loss rate of glacier area in the Yellow River source area in 2010-2018 was more than twice that in 2000-2010.The glacier change is primarily attributed to the significant rise in temperature during the ablation period.Some other factors including the size,orientation and terminus elevation of glaciers also contributed to the heterogeneity of glacier change.展开更多
基金the research was supported by National Natural Science Foundation (No. 40771172)Knowledge innovation project of the Chinese Academy of Sciences (No. kzcx2-yw-308)
文摘Habitat loss and fragmentation are mainly associated with population decrease of endangered species and biodiversity loss. The habitat suitability maps of red-crowned crane （Grusjaponensis） in 1992, 1999 and 2006 were produced by using Ecological Niche Suitability Model （ENSM） in Yellow River Delta Nature Reserve （118°33′-119°20′E longitude, 37°35′-38°12′N latitude）, Shandong Province, China. Based on the habitat suitability maps, the causation and change law of habitat loss and fragmentation of red-crowned crane were analyzed by selecting a series of landscape pattern indices. Results showed that due to scarcities of fresh water sources, habitat suitability of red-crowned crane in 1999 was inferior to that in 1992 and 2006 no matter whether human disturbances existed or not. Besides, human disturbance activities, especially road disturbances, increased rapidly during the period of 1992-2006. This worsened the habitat loss and frag- mentation of red-crowned crane, and led to degrading habitat suitability of red-crowned crane in 2006, compared with that in 1992. In conclusion, fresh water sources and human disturbance activities are the two main factors that drive the habitat suitability change of red-crowned crane.
基金Under the auspices of the National Key R&D Program of China(No.2017YFC0505906)the National Natural Science Foundation of China(No.51639001,51379012)the Interdiscipline Research Funds of Beijing Normal University
文摘Plant invasion alters the fundamental structure and function of native ecosystems by affecting the biogeochemical pools and fluxes of materials and energy. Native(Suaeda salsa) and invasive(Spartina alterniflora) salt marshes were selected to study the effects of Spartina alterniflora invasion on soil organic carbon(SOC) contents and stocks in the Yellow River Delta. Results showed that the SOC contents(g/kg) and stocks(kg/m^2) were significantly increased(P < 0.05) after Spartina alterniflora invasion of seven years, especially for the surface soil layer(0–20 cm). The SOC contents exhibited an even distribution along the soil profiles in native salt marshes, while the SOC contents were gradually decreased with depth after Spartina alterniflora invasion of seven years. The natural ln response ratios(Ln RR) were applied to identify the effects of short-term Spartina alterniflora invasion on the SOC stocks. We also found that Spartina alterniflora invasion might cause soil organic carbon losses in a short-term phase(2–4 years in this study) due to the negative Ln RR values, especially for 20–60 cm depth. And the SOCD in surface layer(0–20 cm) do not increase linearly with the invasive age. Spearman correlation analysis revealed that silt + clay content was exponentially related with SOC in surface layer(Adjusted R^2 = 0.43, P < 0.001), suggesting that soil texture could play a key role in SOC sequestration of coastal salt marshes.
基金This study was supported equally by the National Key R&D Program of China(2017YFC0505200 to H Sun)the Major Program of the National Natural Science Foundation of China(31590823 to H Sun)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA20050203 to H Sun)USDA National Institute of Food and Agriculture(McIntire Stennis#101869 to DS).
文摘Previous attempts to elucidate the drivers of speciation mechanisms and spatial distribution patterns of biodiversity in mountain regions have treated different floras within a single geological region as one flora,ignoring the potential contributions of high habitat/ecosystem heterogeneity.Furthermore,current conservation strategies largely focus on forest ecosystems and/or specific flagship species,ignoring marginal ecosystems,leaving species in these ecosystems at risk.Here,we compared the spatial patterns of biodiversity and the potential drivers of these patterns in the river valley and subnival ecosystems of the Hengduan Mountains region(HDM)in southwestern China.Specifically,we compared spatial patterns of diversity,endemism,and threatened species in these ecosystems based on both traditional measurements and recent phylogenetic approaches.We then examined how those patterns were related to environmental factors and human activity in these same regions.We found that the middle-southern HDM supports the highest diversity and endemism for the river valley and subnival ecosystems;however,the distribution patterns of neo-and paleo-endemism in these two ecosystems differ.Regression models indicate that habitat diversity and paleo-climatic fluctuation are important drivers of diversity and endemism for these two ecosystems.Temperature and precipitation,however,showed different influences on the spatial patterns in different ecosystems.Categorical analysis of neo-and paleoendemism(CANAPE)indicated that most endemism centers are not covered by current nature reserves.Moreover,the intensity of human activity is highest in the southern and southeastern HDM,which coincides with the distribution patterns of diversity,mixed-endemism and high-priority(and threatened)species.These findings suggest that different floras within a single geographic/floristic region respond differently to environmental factors and show different spatial phylogenetic patterns.We,therefore,recommend that future research into the drivers of biodiversity consider the contributions of various ecosystem types within a single geological region.This study also provides a theoretical basis for protecting habitat diversity.Our work confirms that current conservation efforts are insufficient to protect ecosystem diversity in the river valley and subnival ecosystems of the Hengduan Mountains.Therefore,we recommend the establishment of nature reserves in the regions identified in this study;furthermore,we strongly recommend improving current and establishing new management policies for biodiversity conservation in this region.
基金National Natural Science Foundation of China,No.41861013,No.42071089,No.42161027National Key Research Program of China,No.2019YFE0127700+1 种基金Open Research Foundation of National Cryosphere Desert Data Center,No.20D02The Northwest Normal University Graduate Research Grant Program,No.2019KYZZ012054。
文摘The glaciers in the Sanjiangyuan Nature Reserve of China(SNRC)are a significant water resource for the Yangtze,Yellow,and Mekong rivers.Based on Landsat Thematic Mapper(TM)/Operational Land Imager(OLI)images acquired in 2000,2010,and 2018,the outlines of glaciers in the SNRC were obtained by combining band ratio method with manual interpretation.There were 1714 glaciers in the SNRC in 2018,with an area of 2331.15±54.84 km^(2),an ice volume of 188.90±6.41 km3,and an average length of 1475.4±15 m.During 2000-2018,the corresponding values of glaciers decreased by 69,271.95±132.06 km^(2),18.59±8.83 km3,and 84.75±34 m,respectively.Glaciers in the Yangtze River source area witnessed the largest area loss(-154.45 km^(2)),whereas glaciers in the Mekong River source area experienced the fastest area loss(-2.02%·a-1)and the maximum reduction of the average length(-125.82 m).Overall,the retreat of glaciers in the SNRC exhibited an accelerating trend.Especially,the loss rate of glacier area in the Yellow River source area in 2010-2018 was more than twice that in 2000-2010.The glacier change is primarily attributed to the significant rise in temperature during the ablation period.Some other factors including the size,orientation and terminus elevation of glaciers also contributed to the heterogeneity of glacier change.
