How vegetation phenology responds to climate change is a key to the understanding of the mechanisms driving historic and future changes in regional terrestrial ecosystem productivity. Based on the 250-m and 8-day mode...How vegetation phenology responds to climate change is a key to the understanding of the mechanisms driving historic and future changes in regional terrestrial ecosystem productivity. Based on the 250-m and 8-day moderate resolution imaging spectroradiometer(MODIS) normalized difference vegetation index(NDVI) data for 2000-2014 in the Three-River Source Region(TRSR) of Qinghai Province, China, i.e., the hinterland of the Tibetan Plateau, we extracted relevant vegetation phenological information(e.g., start, end, and length of growing season) and analyzed the changes in the TRSR vegetation in response to climate change. The results reveal that, under the increasingly warm and humid climate, the start of vegetation growing season(SOS) advanced 1.03 day yr-1 while the end of vegetation growing season(EOS) exhibited no significant changes, which led to extended growing season length. It is found that the SOS was greatly affected by the preceding winter precipitation, with progressively enhanced precipitation facilitating an earlier SOS. Moreover, as the variations of SOS and its trend depended strongly on topography, we estimated the elevation break-points for SOS. The lower the elevations were, the earlier the SOS started. In the areas below 3095-m elevation, the SOS delay changed rapidly with increasing elevation;whereas above that, the SOS changes were relatively minor. The SOS trend had three elevation break-points at 2660, 3880, and 5240 m.展开更多
Many plants have high ornamental value during specific phenophases, and plant phenology correlates highly with seasonal vegetation landscape. Determination of the span and spatiotemporal patterns of the tourism season...Many plants have high ornamental value during specific phenophases, and plant phenology correlates highly with seasonal vegetation landscape. Determination of the span and spatiotemporal patterns of the tourism season for ornamental plants could provide tourism administrators and the tourists themselves with a theoretical basis for making travel arrangements. Based on data derived from on-the-ground observations of three phenophases, specifically first leafing date, full flowering date, and end of leaf coloring date, and corre- sponding meteorological data at 12 sites in China, we divided the tourism season into its starting date, peak （best date） and end date for ornamental plants by computing frequency distributions of these phenophases. We also determined how the peak of this tourism season changed during the course of the past 50 years. We found that： （1） The peak of the tourism season ranged from March 16 （in Guilin） to May 5 （in Harbin） for first leafing, from April 3 （in Kunming） to May 24 （in Mudanjiang） for full flowering, and from October 1 （in Mudanjiang） to November 30 （in Shanghai） for leaf coloring. As might be expected, the peaks of both the first leafing and full flowering tourism seasons were positively associated with latitude, while for leaf coloring it was negatively correlated with latitude. （2） The ideal tourism season for first leafing and full flowering advanced by more than 0.16 days/year over the past 50 years in Beijing and Xi＇an, while the peak of the tourism season for leaf coloring became significantly delayed （by 0.16 days/year in Beijing and 0.21 days/year in Xi＇an）. （3） The tourism season was significantly associated with temperature across related phenological observation sites. The ideal time for first leafing and full flowering was determined to have advanced, respectively, by 4.02 days and 4.04 days per 1℃ increase in the spring （March-May） temperature. From September to November, the best time for leaf coloring correlate展开更多
科学地规划游客的数量与时段已经成为当前国家公园迫切需要解决的问题。基于2000—2018年MODIS 250 m NDVI数据、土地覆盖/利用数据、90 m高程(DEM)数据、地理信息数据和气象资料等,分析研究了武夷山国家公园不同景区活动类型(保护区、...科学地规划游客的数量与时段已经成为当前国家公园迫切需要解决的问题。基于2000—2018年MODIS 250 m NDVI数据、土地覆盖/利用数据、90 m高程(DEM)数据、地理信息数据和气象资料等,分析研究了武夷山国家公园不同景区活动类型(保护区、景区和过渡区)森林植被的生长季、NDVI年际变化趋势和脆弱性。结果表明:(1)相对于保护区植被生长季10月份结束,景区植被生长季结束期提前,最早提前到9月份。(2)2000—2018年气候变化和景区活动均带来植被指数的增加,但景区活动影响大于气候变化影响。(3)景区活动加重森林植被的脆弱性,其脆弱性程度呈景区>过渡区>保护区。(4)景区活动对森林植被呈负作用,但正在发生的气候变暖和景区有效管理可在一定程度上补偿这一负作用。研究结果可为武夷山国家公园制定旅游时间和游客数量提供决策依据。展开更多
Soil enzymes play a vital role in biogeochemical cycling and ecosystem functions.In this study,we examined the response of six soil enzymes to changes in physicochemical properties resulting from changes in season and...Soil enzymes play a vital role in biogeochemical cycling and ecosystem functions.In this study,we examined the response of six soil enzymes to changes in physicochemical properties resulting from changes in season and vegetation and geological conditions.Catalase,urease,acid phosphatase,invertase,amylase,and cellulase not only promote carbon,nitrogen,and phosphorus cycling,but also participate in the decomposition of harmful substances.Thirty-six soil samples were collected from karst and non-karst areas in two different seasons and from three different types of vegetation in Yunnan province,southwest China.Both vegetation types and season had significant effects on soil physicochemical properties and enzyme activities.In the same plot,soil water content,electrical conductivity,organic carbon,total nitrogen,and total phosphorus increased in the rainy season,indicating enhanced microbial metabolic activity.With the exception of urease activity,the remaining five enzymes showed higher activity in the rainy season.Changes in activities between the two seasons were significant in all samples.In the same season,activity levels of soil enzymes were higher in karst areas than in non-karst areas,and higher in natural forest than in artificial forests.The transformative abilities of soil elements are higher in karst areas than in non-karst areas,and higher in natural forests than in artificial forests.Correlation analysis showed that the activities of the six enzymes correlated significantly;however,soil physical and chemical indices,such as organic matter,pH,and moisture,which are essential for enzyme activity,differed by season.Redundancy analysis also revealed that the main factors influencing enzyme activity differed between the two seasons.The results from this study provide a theoretical basis for further research on the restoration of natural ecological systems in karst landscapes.展开更多
植被物候是监测陆地生态系统和全球气候变化的重要生物指标。基于经典遥感植被指数的陆表物候监测在不同植被类型的精确分析方面存在较大挑战,日光诱导叶绿素荧光(SIF)可以直接反映植被实际光合作用的动态变化,能够更精确地刻画出植被...植被物候是监测陆地生态系统和全球气候变化的重要生物指标。基于经典遥感植被指数的陆表物候监测在不同植被类型的精确分析方面存在较大挑战,日光诱导叶绿素荧光(SIF)可以直接反映植被实际光合作用的动态变化,能够更精确地刻画出植被的年际变异。本研究基于2001~2020年GOSIF数据集,通过D-L拟合函数和动态阈值法提取东北地区植被物候参数,结合一元线性回归分析、稳定性和持续性分析,在多时空尺度下分析2001~2020年东北地区植被物候的时空演变特征,并探讨植被物候对气候变化的响应机制。结果表明:(1)植被生长季开始(Start of Season,SOS)、结束(EndofSeason,EOS)、生长季长度(LengthofSeason,LOS)和生长峰值(Position of Peak,POP)整体上分别呈现出提前、推迟、延长和提前趋势;(2)草丛SOS提前、EOS推迟趋势较为显著,针叶林EOS提前趋势显著;SOS提前、EOS推迟导致LOS延长,除针叶林外,所有植被类型LOS均呈现出延长趋势;除草丛和草原外,其余植被类型POP均呈提前趋势;(3)20年来植被SOS、EOS、LOS和POP变化较为稳定,变异系数均小于0.1;(4)大部分区域植被SOS、EOS、LOS和POP的H值介于0.35~0.5之间,说明其变化趋势与过去相反,将呈现微弱延迟、提前、缩短和延长的趋势;(5)整体上气温和降水对植被物候的影响机制相反,即气温升高(降水增加)导致SOS和POP提前(推迟)、EOS推迟(提前)以及LOS延长(缩短);相对湿度与植被物候参数均呈负相关关系。本研究结果有助于理解植被进行光合作用的时空格局变化及对气候变化的响应机制,也为东北地区生态环境的评估和管理提供参考。展开更多
基金Supported by the National Key Research and Development Program of China(2016YFC0500203 and 2017YFC0503803)National Natural Science Foundation of China(31971507)Science and Technology Program of Qinghai Province(2018-ZJ-T09)。
文摘How vegetation phenology responds to climate change is a key to the understanding of the mechanisms driving historic and future changes in regional terrestrial ecosystem productivity. Based on the 250-m and 8-day moderate resolution imaging spectroradiometer(MODIS) normalized difference vegetation index(NDVI) data for 2000-2014 in the Three-River Source Region(TRSR) of Qinghai Province, China, i.e., the hinterland of the Tibetan Plateau, we extracted relevant vegetation phenological information(e.g., start, end, and length of growing season) and analyzed the changes in the TRSR vegetation in response to climate change. The results reveal that, under the increasingly warm and humid climate, the start of vegetation growing season(SOS) advanced 1.03 day yr-1 while the end of vegetation growing season(EOS) exhibited no significant changes, which led to extended growing season length. It is found that the SOS was greatly affected by the preceding winter precipitation, with progressively enhanced precipitation facilitating an earlier SOS. Moreover, as the variations of SOS and its trend depended strongly on topography, we estimated the elevation break-points for SOS. The lower the elevations were, the earlier the SOS started. In the areas below 3095-m elevation, the SOS delay changed rapidly with increasing elevation;whereas above that, the SOS changes were relatively minor. The SOS trend had three elevation break-points at 2660, 3880, and 5240 m.
基金National Natural Science Foundation of China, No.41171043 National Basic Research Program of China, No.2012CB955304+1 种基金 Major National Research Program of Scientific Instruments, No.41427805 National Natural Science Foundation of China, No.41030101
文摘Many plants have high ornamental value during specific phenophases, and plant phenology correlates highly with seasonal vegetation landscape. Determination of the span and spatiotemporal patterns of the tourism season for ornamental plants could provide tourism administrators and the tourists themselves with a theoretical basis for making travel arrangements. Based on data derived from on-the-ground observations of three phenophases, specifically first leafing date, full flowering date, and end of leaf coloring date, and corre- sponding meteorological data at 12 sites in China, we divided the tourism season into its starting date, peak （best date） and end date for ornamental plants by computing frequency distributions of these phenophases. We also determined how the peak of this tourism season changed during the course of the past 50 years. We found that： （1） The peak of the tourism season ranged from March 16 （in Guilin） to May 5 （in Harbin） for first leafing, from April 3 （in Kunming） to May 24 （in Mudanjiang） for full flowering, and from October 1 （in Mudanjiang） to November 30 （in Shanghai） for leaf coloring. As might be expected, the peaks of both the first leafing and full flowering tourism seasons were positively associated with latitude, while for leaf coloring it was negatively correlated with latitude. （2） The ideal tourism season for first leafing and full flowering advanced by more than 0.16 days/year over the past 50 years in Beijing and Xi＇an, while the peak of the tourism season for leaf coloring became significantly delayed （by 0.16 days/year in Beijing and 0.21 days/year in Xi＇an）. （3） The tourism season was significantly associated with temperature across related phenological observation sites. The ideal time for first leafing and full flowering was determined to have advanced, respectively, by 4.02 days and 4.04 days per 1℃ increase in the spring （March-May） temperature. From September to November, the best time for leaf coloring correlate
文摘科学地规划游客的数量与时段已经成为当前国家公园迫切需要解决的问题。基于2000—2018年MODIS 250 m NDVI数据、土地覆盖/利用数据、90 m高程(DEM)数据、地理信息数据和气象资料等,分析研究了武夷山国家公园不同景区活动类型(保护区、景区和过渡区)森林植被的生长季、NDVI年际变化趋势和脆弱性。结果表明:(1)相对于保护区植被生长季10月份结束,景区植被生长季结束期提前,最早提前到9月份。(2)2000—2018年气候变化和景区活动均带来植被指数的增加,但景区活动影响大于气候变化影响。(3)景区活动加重森林植被的脆弱性,其脆弱性程度呈景区>过渡区>保护区。(4)景区活动对森林植被呈负作用,但正在发生的气候变暖和景区有效管理可在一定程度上补偿这一负作用。研究结果可为武夷山国家公园制定旅游时间和游客数量提供决策依据。
基金This work was supported by the National Key Research and Development Program of China(2016YFC0502500,2016YFC0502504)the National Natural Science Foundation of China(315005831008509)the Special fund for basic scientific research expenses of central public welfare scientific research institutes(CAFYBB2014ZD006,CAFYBB2016QB020).
文摘Soil enzymes play a vital role in biogeochemical cycling and ecosystem functions.In this study,we examined the response of six soil enzymes to changes in physicochemical properties resulting from changes in season and vegetation and geological conditions.Catalase,urease,acid phosphatase,invertase,amylase,and cellulase not only promote carbon,nitrogen,and phosphorus cycling,but also participate in the decomposition of harmful substances.Thirty-six soil samples were collected from karst and non-karst areas in two different seasons and from three different types of vegetation in Yunnan province,southwest China.Both vegetation types and season had significant effects on soil physicochemical properties and enzyme activities.In the same plot,soil water content,electrical conductivity,organic carbon,total nitrogen,and total phosphorus increased in the rainy season,indicating enhanced microbial metabolic activity.With the exception of urease activity,the remaining five enzymes showed higher activity in the rainy season.Changes in activities between the two seasons were significant in all samples.In the same season,activity levels of soil enzymes were higher in karst areas than in non-karst areas,and higher in natural forest than in artificial forests.The transformative abilities of soil elements are higher in karst areas than in non-karst areas,and higher in natural forests than in artificial forests.Correlation analysis showed that the activities of the six enzymes correlated significantly;however,soil physical and chemical indices,such as organic matter,pH,and moisture,which are essential for enzyme activity,differed by season.Redundancy analysis also revealed that the main factors influencing enzyme activity differed between the two seasons.The results from this study provide a theoretical basis for further research on the restoration of natural ecological systems in karst landscapes.
文摘植被物候是监测陆地生态系统和全球气候变化的重要生物指标。基于经典遥感植被指数的陆表物候监测在不同植被类型的精确分析方面存在较大挑战,日光诱导叶绿素荧光(SIF)可以直接反映植被实际光合作用的动态变化,能够更精确地刻画出植被的年际变异。本研究基于2001~2020年GOSIF数据集,通过D-L拟合函数和动态阈值法提取东北地区植被物候参数,结合一元线性回归分析、稳定性和持续性分析,在多时空尺度下分析2001~2020年东北地区植被物候的时空演变特征,并探讨植被物候对气候变化的响应机制。结果表明:(1)植被生长季开始(Start of Season,SOS)、结束(EndofSeason,EOS)、生长季长度(LengthofSeason,LOS)和生长峰值(Position of Peak,POP)整体上分别呈现出提前、推迟、延长和提前趋势;(2)草丛SOS提前、EOS推迟趋势较为显著,针叶林EOS提前趋势显著;SOS提前、EOS推迟导致LOS延长,除针叶林外,所有植被类型LOS均呈现出延长趋势;除草丛和草原外,其余植被类型POP均呈提前趋势;(3)20年来植被SOS、EOS、LOS和POP变化较为稳定,变异系数均小于0.1;(4)大部分区域植被SOS、EOS、LOS和POP的H值介于0.35~0.5之间,说明其变化趋势与过去相反,将呈现微弱延迟、提前、缩短和延长的趋势;(5)整体上气温和降水对植被物候的影响机制相反,即气温升高(降水增加)导致SOS和POP提前(推迟)、EOS推迟(提前)以及LOS延长(缩短);相对湿度与植被物候参数均呈负相关关系。本研究结果有助于理解植被进行光合作用的时空格局变化及对气候变化的响应机制,也为东北地区生态环境的评估和管理提供参考。
