The Three-River Headwater Region（TRHR）, known as the ＂Water Tower of China＂, is an important ecological shelter for national security interests and regional sustainable development activities for many downstream r...The Three-River Headwater Region（TRHR）, known as the ＂Water Tower of China＂, is an important ecological shelter for national security interests and regional sustainable development activities for many downstream regions in China and a number of Southeast Asian countries. The TRHR is a high-elevation, cold environment with a unique, but typical alpine vegetation system. Net primary productivity（NPP） is a key vegetation parameter and ecological indicator that can reflect both natural environmental changes and carbon budget levels. Given the unique geographical environment and strategic location of the TRHR, many scholars have estimated NPP of the TRHR by using different methods; however, these estimates vary greatly for a number of reasons. To date, there is no paper that has reviewed and assessed NPP estimation studies conducted in the TRHR. Therefore, in this paper, we（1） summarized the related methods and results of NPP estimation in the TRHR in a systematic review of previous research;（2） discussed the suitability of existing methods for estimating NPP in the TRHR and highlighted the most significant challenges; and（3） assessed the estimated NPP results. Finally, developmental directions of NPP estimation in the TRHR were prospected.展开更多
Relative roles of climate change and human activities in desertification are the hotspot of research on desertification dynamic and its driving mechanism.To overcome the shortcomings of existing studies,this paper sel...Relative roles of climate change and human activities in desertification are the hotspot of research on desertification dynamic and its driving mechanism.To overcome the shortcomings of existing studies,this paper selected net primary productivity （NPP） as an indicator to analyze desertification dynamic and its impact factors.In addition,the change trends of actual NPP,potential NPP and HNPP （human appropriation of NPP,the difference between potential NPP and actual NPP） were used to analyze the desertification dynamic and calculate the relative roles of climate change,human activities and a combination of the two factors in desertification.In this study,the Moderate Resolution Imaging Spectroradiometer （MODIS）-Normalised Difference Vegetation Index （NDVI） and meteorological data were utilized to drive the Carnegie-Ames-Stanford Approach （CASA） model to calculate the actual NPP from 2001 to 2010 in the Heihe River Basin.Potential NPP was estimated using the Thornthwaite Memorial model.Results showed that 61％ of the whole basin area underwent land degradation,of which 90.5％ was caused by human activities,8.6％ by climate change,and 0.9％ by a combination of the two factors.On the contrary,1.5％ of desertification reversion area was caused by human activities and 90.7％ by climate change,the rest 7.8％ by a combination of the two factors.Moreover,it was demonstrated that 95.9％ of the total actual NPP decrease was induced by human activities,while 69.3％ of the total actual NPP increase was caused by climate change.The results revealed that climate change dominated desertification reversion,while human activities dominated desertification expansion.Moreover,the relative roles of both climate change and human activities in desertification possessed great spatial heterogeneity.Additionally,ecological protection policies should be enhanced in the Heihe River Basin to prevent desertification expansion under the condition of climate change.展开更多
净初级生产力(NPP)是评价森林生态系统碳收支状况的重要指标,精确评估森林NPP变化以应对气候变化有着重要意义。以江西省修河流域为研究区,基于参数本地化后的Biome-BGC模型模拟了1960—2021年6种亚热带典型森林NPP动态变化,并结合温度...净初级生产力(NPP)是评价森林生态系统碳收支状况的重要指标,精确评估森林NPP变化以应对气候变化有着重要意义。以江西省修河流域为研究区,基于参数本地化后的Biome-BGC模型模拟了1960—2021年6种亚热带典型森林NPP动态变化,并结合温度、降水及气候变化情景分析了森林NPP对温度、降水的响应。结果表明:(1)1960—2021年,修河流域不同森林类型的NPP由高到低依次为:竹林(655.20 g C·m^(-2)·a^(-1))>常绿针叶林(629.42 g C·m^(-2)·a^(-1))>常绿阔叶林(600.01 g C·m^(-2)·a^(-1))>常绿针阔混交林(596.98 g C·m^(-2)·a^(-1))>落叶阔叶林(325.20 g C·m^(-2)·a^(-1))>灌木林(266.43 g C·m^(-2)·a^(-1))。(2)6种典型森林NPP的月际变化表明,落叶阔叶林NPP呈单峰变化并在8月份达到最高值,其他森林NPP均在8月份降至峰谷并呈双峰趋势。除落叶阔叶林和灌木林以外,其他森林NPP在7—9月与温度大多呈极显著负相关性,而与降水呈正相关,表明夏季温度升高、降水减少极大影响了植被生长。(3)从气象因子的拟合强度来看,NPP对温度的响应强度大于降水,温度与竹林NPP及落叶阔叶林NPP的拟合较强(R^(2)>0.46;P<0.01);而降水与常绿针叶林、竹林、灌木林及阔叶落叶林NPP都是较弱的拟合关系(R^(2)<0.21;P<0.01)。(4)未来气候情景中,适当升温有助于促进植被的生长,但升温超过阈值后NPP将受到抑制;在降水情景中,NPP与降水呈正相关性。NPP对温度的响应幅度远大于降水,且温度和降水的组合变化情景的拟合优度高于单一变化情景。展开更多
地表基质与植被覆盖空间错位是人工林地退化的重要原因,探究地表基质与植被覆盖的耦合关系,掌握不同地表基质物性结构异质性特征及其对植被生长的约束作用,对生态修复精准施策和植被恢复成效提升具有重要意义。渭北旱腰带位于黄河中游...地表基质与植被覆盖空间错位是人工林地退化的重要原因,探究地表基质与植被覆盖的耦合关系,掌握不同地表基质物性结构异质性特征及其对植被生长的约束作用,对生态修复精准施策和植被恢复成效提升具有重要意义。渭北旱腰带位于黄河中游黄土丘陵沟壑与关中平原的过渡区,是关中平原城市群北部的重要生态屏障。然而,受频繁的矿产资源开采活动影响,该区自然植被破坏严重。同时,在干旱气候、复杂地质和破碎地形的交织作用下,地表基质物性结构空间差异显著,不同地表基质类型水土保持功能参差不齐,导致植被恢复成效不均,生态系统脆弱性突出,严重制约了渭北旱腰带生态屏障功能的发挥。以黄河中游渭北旱腰带典型区域——陕西韩城地区为研究对象,基于地表基质剖面和植被生态样方综合调查,分析了不同地表基质物性结构异质性特征及其与上覆植被群落结构和根系构型的关系;结合植被生态指数时间序列,探讨了地表基质物性结构异质性对植被生态的影响。结果表明:泥质岩、碎屑岩夹泥质岩、冲洪积沙和碎屑岩地表基质的土壤发生层结构完整且厚度大,植被覆盖度均大于80%,2000~2023年植被净初级生产力(NPP)多年平均值相对较高,为378.01~430.77 kg C·m^(-2)·年^(-1),但受孔隙裂隙发育程度和深度的影响,植被群落结构存在差异;碳酸盐岩、冲洪积砾和花岗片麻岩地表基质植被覆盖度均小于50%,净初级生产力多年平均值也相对较低(156.21~320.04 kg C·m^(-2)·年^(-1)),其中花岗片麻岩地表基质裂隙过于发育(平均裂隙密度为4.73 m·m^(-2)),净初级生产力主要由稀疏的深根性乔木贡献,因此具有研究区最低的净初级生产力多年平均值(156.21 kg C·m^(-2)·年^(-1));风积物地表基质虽然土层深厚,但是因垂直节理发育,保水保肥能力弱,地表多生长灌木和草本,零星生长深根系耐旱乔木,净初级生产力多年平均值处于中等水平(378.29 kg C·m^(-2)·年^(-1))。植被覆盖度与地表基质表层土壤厚度间具有极显著的正相关关系(p<0.01),与宽度大于1 mm的裂隙密度之间也呈现显著的正相关关系(p<0.05),反映了地表基质物性结构(物质组成、空间结构、孔隙裂隙等)通过影响植被根系生长和水分吸收,决定了渭北旱腰带地表林草植被生长和净初级生产力水平。展开更多
基金National Key Research and Development Program of China,No.2016YFC0500205National Basic Research Program of China(973 Program),No.2015CB954103,No.2015CB954101
文摘The Three-River Headwater Region（TRHR）, known as the ＂Water Tower of China＂, is an important ecological shelter for national security interests and regional sustainable development activities for many downstream regions in China and a number of Southeast Asian countries. The TRHR is a high-elevation, cold environment with a unique, but typical alpine vegetation system. Net primary productivity（NPP） is a key vegetation parameter and ecological indicator that can reflect both natural environmental changes and carbon budget levels. Given the unique geographical environment and strategic location of the TRHR, many scholars have estimated NPP of the TRHR by using different methods; however, these estimates vary greatly for a number of reasons. To date, there is no paper that has reviewed and assessed NPP estimation studies conducted in the TRHR. Therefore, in this paper, we（1） summarized the related methods and results of NPP estimation in the TRHR in a systematic review of previous research;（2） discussed the suitability of existing methods for estimating NPP in the TRHR and highlighted the most significant challenges; and（3） assessed the estimated NPP results. Finally, developmental directions of NPP estimation in the TRHR were prospected.
基金supported by the National Basic Research Program of China(2010CB950702)the National High Technology Research and Development Program of China(2007AA10Z231)+2 种基金the National Natural Science Foundation of China(40871012,J1103512,J1210026)the Asia-Pacific Network(ARCP-2012-SP25-Li)the Australian Agency for International Development(64828)
文摘Relative roles of climate change and human activities in desertification are the hotspot of research on desertification dynamic and its driving mechanism.To overcome the shortcomings of existing studies,this paper selected net primary productivity （NPP） as an indicator to analyze desertification dynamic and its impact factors.In addition,the change trends of actual NPP,potential NPP and HNPP （human appropriation of NPP,the difference between potential NPP and actual NPP） were used to analyze the desertification dynamic and calculate the relative roles of climate change,human activities and a combination of the two factors in desertification.In this study,the Moderate Resolution Imaging Spectroradiometer （MODIS）-Normalised Difference Vegetation Index （NDVI） and meteorological data were utilized to drive the Carnegie-Ames-Stanford Approach （CASA） model to calculate the actual NPP from 2001 to 2010 in the Heihe River Basin.Potential NPP was estimated using the Thornthwaite Memorial model.Results showed that 61％ of the whole basin area underwent land degradation,of which 90.5％ was caused by human activities,8.6％ by climate change,and 0.9％ by a combination of the two factors.On the contrary,1.5％ of desertification reversion area was caused by human activities and 90.7％ by climate change,the rest 7.8％ by a combination of the two factors.Moreover,it was demonstrated that 95.9％ of the total actual NPP decrease was induced by human activities,while 69.3％ of the total actual NPP increase was caused by climate change.The results revealed that climate change dominated desertification reversion,while human activities dominated desertification expansion.Moreover,the relative roles of both climate change and human activities in desertification possessed great spatial heterogeneity.Additionally,ecological protection policies should be enhanced in the Heihe River Basin to prevent desertification expansion under the condition of climate change.
文摘净初级生产力(NPP)是评价森林生态系统碳收支状况的重要指标,精确评估森林NPP变化以应对气候变化有着重要意义。以江西省修河流域为研究区,基于参数本地化后的Biome-BGC模型模拟了1960—2021年6种亚热带典型森林NPP动态变化,并结合温度、降水及气候变化情景分析了森林NPP对温度、降水的响应。结果表明:(1)1960—2021年,修河流域不同森林类型的NPP由高到低依次为:竹林(655.20 g C·m^(-2)·a^(-1))>常绿针叶林(629.42 g C·m^(-2)·a^(-1))>常绿阔叶林(600.01 g C·m^(-2)·a^(-1))>常绿针阔混交林(596.98 g C·m^(-2)·a^(-1))>落叶阔叶林(325.20 g C·m^(-2)·a^(-1))>灌木林(266.43 g C·m^(-2)·a^(-1))。(2)6种典型森林NPP的月际变化表明,落叶阔叶林NPP呈单峰变化并在8月份达到最高值,其他森林NPP均在8月份降至峰谷并呈双峰趋势。除落叶阔叶林和灌木林以外,其他森林NPP在7—9月与温度大多呈极显著负相关性,而与降水呈正相关,表明夏季温度升高、降水减少极大影响了植被生长。(3)从气象因子的拟合强度来看,NPP对温度的响应强度大于降水,温度与竹林NPP及落叶阔叶林NPP的拟合较强(R^(2)>0.46;P<0.01);而降水与常绿针叶林、竹林、灌木林及阔叶落叶林NPP都是较弱的拟合关系(R^(2)<0.21;P<0.01)。(4)未来气候情景中,适当升温有助于促进植被的生长,但升温超过阈值后NPP将受到抑制;在降水情景中,NPP与降水呈正相关性。NPP对温度的响应幅度远大于降水,且温度和降水的组合变化情景的拟合优度高于单一变化情景。
文摘地表基质与植被覆盖空间错位是人工林地退化的重要原因,探究地表基质与植被覆盖的耦合关系,掌握不同地表基质物性结构异质性特征及其对植被生长的约束作用,对生态修复精准施策和植被恢复成效提升具有重要意义。渭北旱腰带位于黄河中游黄土丘陵沟壑与关中平原的过渡区,是关中平原城市群北部的重要生态屏障。然而,受频繁的矿产资源开采活动影响,该区自然植被破坏严重。同时,在干旱气候、复杂地质和破碎地形的交织作用下,地表基质物性结构空间差异显著,不同地表基质类型水土保持功能参差不齐,导致植被恢复成效不均,生态系统脆弱性突出,严重制约了渭北旱腰带生态屏障功能的发挥。以黄河中游渭北旱腰带典型区域——陕西韩城地区为研究对象,基于地表基质剖面和植被生态样方综合调查,分析了不同地表基质物性结构异质性特征及其与上覆植被群落结构和根系构型的关系;结合植被生态指数时间序列,探讨了地表基质物性结构异质性对植被生态的影响。结果表明:泥质岩、碎屑岩夹泥质岩、冲洪积沙和碎屑岩地表基质的土壤发生层结构完整且厚度大,植被覆盖度均大于80%,2000~2023年植被净初级生产力(NPP)多年平均值相对较高,为378.01~430.77 kg C·m^(-2)·年^(-1),但受孔隙裂隙发育程度和深度的影响,植被群落结构存在差异;碳酸盐岩、冲洪积砾和花岗片麻岩地表基质植被覆盖度均小于50%,净初级生产力多年平均值也相对较低(156.21~320.04 kg C·m^(-2)·年^(-1)),其中花岗片麻岩地表基质裂隙过于发育(平均裂隙密度为4.73 m·m^(-2)),净初级生产力主要由稀疏的深根性乔木贡献,因此具有研究区最低的净初级生产力多年平均值(156.21 kg C·m^(-2)·年^(-1));风积物地表基质虽然土层深厚,但是因垂直节理发育,保水保肥能力弱,地表多生长灌木和草本,零星生长深根系耐旱乔木,净初级生产力多年平均值处于中等水平(378.29 kg C·m^(-2)·年^(-1))。植被覆盖度与地表基质表层土壤厚度间具有极显著的正相关关系(p<0.01),与宽度大于1 mm的裂隙密度之间也呈现显著的正相关关系(p<0.05),反映了地表基质物性结构(物质组成、空间结构、孔隙裂隙等)通过影响植被根系生长和水分吸收,决定了渭北旱腰带地表林草植被生长和净初级生产力水平。
