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1. chinaXiv:202005.00090 [pdf]

Spatial and temporal change patterns of net primary productivity and its response to climate change in the Qinghai–Tibet Plateau of China from 2000 to 2015

GUO Bing; ZANG Wenqian6, YANG Fei; HAN Baomin; CHEN Shuting; LIU Yue; YANG Xiao; HE Tianli; CHEN Xi; LIU Chunting; GONG Rui
Subjects: Biology >> Botany >> Applied botany

The vegetation ecosystem of the Qinghai–Tibet Plateau in China, considered to be the ′′natural laboratory′′ of climate change in the world, has undergone profound changes under the stress of global change. Herein, we analyzed and discussed the spatial-temporal change patterns and the driving mechanisms of net primary productivity (NPP) in the Qinghai–Tibet Plateau from 2000 to 2015 based on the gravity center and correlation coefficient models. Subsequently, we quantitatively distinguished the relative effects of climate change (such as precipitation, temperature and evapotranspiration) and human activities (such as grazing and ecological construction) on the NPP changes using scenario analysis and Miami model based on the MOD17A3 and meteorological data. The average annual NPP in the Qinghai–Tibet Plateau showed a decreasing trend from the southeast to the northwest during 2000–2015. With respect to the inter-annual changes, the average annual NPP exhibited a fluctuating upward trend from 2000 to 2015, with a steep increase observed in 2005 and a high fluctuation observed from 2005 to 2015. In the Qinghai–Tibet Plateau, the regions with the increase in NPP (change rate higher than 10%) were mainly concentrated in the Three-River Source Region, the northern Hengduan Mountains, the middle and lower reaches of the Yarlung Zangbo River, and the eastern parts of the North Tibet Plateau, whereas the regions with the decrease in NPP (change rate lower than –10%) were mainly concentrated in the upper reaches of the Yarlung Zangbo River and the Ali Plateau. The gravity center of NPP in the Qinghai–Tibet Plateau has moved southwestward during 2000–2015, indicating that the increment and growth rate of NPP in the southwestern part is greater than those of NPP in the northeastern part.Further, a significant correlation was observed between NPP and climate factors in the Qinghai–Tibet Plateau. The regions exhibiting a significant correlation between NPP and precipitation were mainly located in the central and eastern Qinghai–Tibet Plateau, and the regions exhibiting a significant correlation between NPP and temperature were mainly located in the southern and eastern Qinghai–Tibet Plateau. Furthermore, the relative effects of climate change and human activities on the NPP changes in the Qinghai–Tibet Plateau exhibited significant spatial differences in three types of zones, i.e., the climate change-dominant zone, the human activity-dominant zone, and the climate change and human activity interaction zone. These research results can provide theoretical and methodological supports to reveal the driving mechanisms of the regional ecosystems to the global change in the Qinghai–Tibet Plateau.

submitted time 2020-05-31 From cooperative journals:《Journal of Arid Land》 Hits2897Downloads278 Comment 0

2. chinaXiv:202004.00050 [pdf]

Spatial and temporal change patterns of net primary productivity and its response to climate change in the Qinghai–Tibet Plateau of China from 2000 to 2015

GUO Bing; ZANG Wenqian; YANG Fei; HAN Baomin; CHEN Shuting; LIU Yue; YANG Xiao; HE Tianli; CHEN Xi; LIU Chunting; GONG Rui
Subjects: Environmental Sciences, Resource Sciences >> Basic Disciplines of Environmental Science and Technology

The vegetation ecosystem of the Qinghai–Tibet Plateau in China, considered to be the ′′natural laboratory′′ of climate change in the world, has undergone profound changes under the stress of global change. Herein, we analyzed and discussed the spatial-temporal change patterns and the driving mechanisms of net primary productivity (NPP) in the Qinghai–Tibet Plateau from 2000 to 2015 based on the gravity center and correlation coefficient models. Subsequently, we quantitatively distinguished the relative effects of climate change (such as precipitation, temperature and evapotranspiration) and human activities (such as grazing and ecological construction) on the NPP changes using scenario analysis and Miami model based on the MOD17A3 and meteorological data. The average annual NPP in the Qinghai–Tibet Plateau showed a decreasing trend from the southeast to the northwest during 2000–2015. With respect to the inter-annual changes, the average annual NPP exhibited a fluctuating upward trend from 2000 to 2015, with a steep increase observed in 2005 and a high fluctuation observed from 2005 to 2015. In the Qinghai–Tibet Plateau, the regions with the increase in NPP (change rate higher than 10%) were mainly concentrated in the Three-River Source Region, the northern Hengduan Mountains, the middle and lower reaches of the Yarlung Zangbo River, and the eastern parts of the North Tibet Plateau, whereas the regions with the decrease in NPP (change rate lower than –10%) were mainly concentrated in the upper reaches of the Yarlung Zangbo River and the Ali Plateau. The gravity center of NPP in the Qinghai–Tibet Plateau has moved southwestward during 2000–2015, indicating that the increment and growth rate of NPP in the southwestern part is greater than those of NPP in the northeastern part. Further, a significant correlation was observed between NPP and climate factors in the Qinghai–Tibet Plateau. The regions exhibiting a significant correlation between NPP and precipitation were mainly located in the central and eastern Qinghai–Tibet Plateau, and the regions exhibiting a significant correlation between NPP and temperature were mainly located in the southern and eastern Qinghai–Tibet Plateau. Furthermore, the relative effects of climate change and human activities on the NPP changes in the Qinghai–Tibet Plateau exhibited significant spatial differences in three types of zones, i.e., the climate change-dominant zone, the human activity-dominant zone, and the climate change and human activity interaction zone. These research results can provide theoretical and methodological supports to reveal the driving mechanisms of the regional ecosystems to the global change in the Qinghai–Tibet Plateau.

submitted time 2020-04-23 From cooperative journals:《Journal of Arid Land》 Hits288Downloads171 Comment 0

3. chinaXiv:201909.00014 [pdf]

Estimation of spatial and temporal changes in net primary production based on Carnegie Ames Stanford Approach (CASA) model in semi-arid rangelands of Semirom County, Iran

Fatemeh HADIAN
Subjects: Geosciences >> Geography

Net primary production (NPP) is an indicator of rangeland ecosystem function. This research assessed the potential of the Carnegie Ames Stanford Approach (CASA) model for estimating NPP and its spatial and temporal changes in semi-arid rangelands of Semirom County, Iran. Using CASA model, we estimated the NPP values based on monthly climate data and the normalized difference vegetation index (NDVI) obtained from the MODIS sensor. Regression analysis was then applied to compare the estimated production data with observed production data. The spatial and temporal changes in NPP and light utilization efficiency (LUE) were investigated in different rangeland vegetation types. The standardized precipitation index (SPI) was also calculated at different time scales and the correlation of SPI with NPP changes was determined. The results indicated that the estimated NPP values varied from 0.00 to 74.48 g C/(m2?a). The observed and estimated NPP values had different correlations, depending on rangeland conditions and vegetation types. The highest and lowest correlations were respectively observed in Astragalus spp.-Agropyron spp. rangeland (R2=0.75) with good condition and Gundelia spp.-Cousinia spp. rangeland (R2=0.36) with poor and very poor conditions. The maximum and minimum LUE values were found in Astragalus spp.-Agropyron spp. rangeland (0.117 g C/MJ) with good condition and annual grasses-annual forbs rangeland (0.010 g C/MJ), respectively. According to the correlations between SPI and NPP changes, the effects of drought periods on NPP depended on vegetation types and rangeland conditions. Annual plants had the highest drought sensitivity while shrubs exhibited the lowest drought sensitivity. The positive effects of wet periods on NPP were less evident in degraded areas where the destructive effects of drought were more prominent. Therefore, determining vegetation types and rangeland conditions is essential in NPP estimation. The findings of this study confirmed the potential of the CASA for estimating rangeland production. Therefore, the model output maps can be used to evaluate, monitor and optimize rangeland management in semi-arid rangelands of Iran where MODIS NPP products are not available.

submitted time 2019-08-30 From cooperative journals:《Journal of Arid Land》 Hits7723Downloads287 Comment 0

4. chinaXiv:201903.00206 [pdf]

山东省植被NPP时空分布特征及驱动因素分析

骆艳; 张松林
Subjects: Biology >> Botany >> Applied botany

为了解区域生态系统植被生产力的分布规律及其变化对区域生态调控的作用,本文基于MOD17A3的年NPP数据,采用一元线性回归分析法和Pearson相关系数法等方法,分析了2000—2014年山东省植被NPP的时空格局变化特征及其气候、人为等因素对其的影响。结果表明:(1)2000—2014年,山东省植被NPP总体呈上升趋势,年均值为442 g C · m-2 · a-1,年总量平均值为63.16 T g C。山东省植被NPP空间分布具有明显的分异特征,其中年均NPP 300 ~ 400 g C · m-2 · a-1的面积最大,占总面积的52.28%,分布于山东省西部的绝大部分区域。(2)山东省植被NPP年增加速率平均值为3.29 g C · m-2 · a-1,增加区域占山东省植被总面积的92.63%。其中,极显著增加区域占山东省总面积的16.56%,主要分布在烟台市、青岛市、日照市、临沂市、潍坊市、东营市和滨州市;显著减少和极显著减少的区域占山东省总面积的1.33%,零星分布在山东省东南部和北部黄河三角洲地区。(3)植被NPP受气候变化和人类活动等因素的共同影响,气候因素中降雨的影响最大,城市化随着人类活动的频繁逐渐成为植被NPP变化的重要驱动力。

submitted time 2019-03-14 From cooperative journals:《广西植物》 Hits1074Downloads213 Comment 0

5. chinaXiv:201811.00060 [pdf]

2000—2015年中国荒漠化土地识别和监测

胡云锋; 张云芝
Subjects: Geosciences >> Geography

荒漠化是生态退化的极端表现形式,指包括气候变异和人类活动在内的种种因素造成的干旱、半干旱和亚湿润干旱区的土地退化。快速和准确地识别中国荒漠化地区,是防范和治理荒漠化的关键。论文针对2000—2015年我国陆地生态系统NPP的变化趋势、稳定性和荒漠化敏感性进行了综合分析,构建了识别荒漠化土地的技术方法。主要结论为:(1)近16年以来,我国内蒙古阴山以南、新疆天山以北、西藏阿里地区、长江以南大部地区,植被净初级生产力均出现了不同程度的下降趋势,且一半以上的区域处于植被生态系统不稳定状况;在全国56.2%的国土属于荒漠化敏感区内,上述区域容易受气候、自然条件、人为干扰变等影响而发生荒漠化。(2)2000年以来,我国土地荒漠化退化区域面积约20.74×104 km2,占国土总面积的2.16%。主要为五大分布区域,即内蒙古高原中部的典型草原和荒漠化草原区、新疆天山—阿尔泰山山地草原区、新疆塔里木河下游的温带荒漠和绿洲区,青藏高原的阿里—昆仑山高寒荒漠区,青海省的青南山高寒草原区。(3)荒漠化进程伴随有生产力下降、植被盖度降低和地表温度不断攀升的地表关键参数演变特征,荒漠化的形成受气候影响显著,降雨的减少是造成土地荒漠化进程突出的主要因素;人类活动、不合理的种植业、畜牧业等在一定程度上对土地荒漠化起到推动作用。

submitted time 2018-11-14 From cooperative journals:《干旱区地理》 Hits5016Downloads657 Comment 0

6. chinaXiv:201711.02376 [pdf]

太行山区植被NPP 时空变化特征及其驱动力分析

李晓荣; 高 会; 韩立朴; 刘金铜
Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Basic Disciplines of Agriculture

本文基于2000—2014 年MODIS NPP 数据, 结合同期土地利用变化、气温、降水和DEM 数据, 运用趋势分析法、相关系数法及分区统计法等方法, 研究了太行山区2000—2014 年植被NPP 时空变化特征, 分析了气温、降水等气候因素和人为因素对植被NPP 变化的影响, 为太行山区植被资源管理及生态环境调控提供参考。研究结果表明: (1)太行山区植被NPP 多年平均值为284.0 g(C)·m?2·a?1, 耕地、林地和草地的NPP 均值分别为302.5 g(C)·m?2·a?1、258.1 g(C)·m?2·a?1、286.5 g(C)·m?2·a?1。(2)2000—2014 年太行山区植被NPP 整体呈上升趋势, 但大部分植被NPP 变化未达到显著水平; 16.17%的植被NPP 显著或极显著升高, 主要分布在太行山区西侧; 0.88%的植被NPP 显著或极显著降低, 零散分布在研究区内。(3)不同植被类型NPP 变化速率为草地>耕地>林地。(4)基于区域平均计算, 太行山区植被NPP 与降水显著正相关(P<0.05), 与气温负相关(P>0.05)。基于像元计算, 植被NPP 与降水显著或极显著正相关区面积比例为23.82%, 主要分布在太行山区北段, 几乎没有显著负相关区; 植被NPP 与气温显著或极显著负相关区面积比例为8.42%, 主要分布在太行山区西侧, 显著或极显著正相关区面积比例为0.81%, 主要分布在太行山区最北端。(5)研究期内气候因子对植被NPP 的升高整体上表现为促进作用, 而人为因素主要表现为抑制作用。太行山区生态环境保护仍应以减少人为干扰为主。

submitted time 2017-11-09 From cooperative journals:《中国生态农业学报》 Hits772Downloads490 Comment 0

7. chinaXiv:201704.00147 [pdf]

2001-2010年疏勒河流域植被净初级生产力时空变化及其与气候因子的关系

潘竟虎,黄克军,李真
Subjects: Biology >> Ecology

通过改进的光能利用率 CASA 模型估算 2001—2010 年间疏勒河流域陆地生态系统的净第一性生产力(NPP),采用线性 趋势分析、变异系数和 Hurst 指数等方法,分析了 NPP 的时空变化特征及其与气候因子的相关性。 结果表明:1疏勒河流域 NPP 的空间分布具有明显差异,空间上呈现西北低、东南高的趋势,且具有较明显的经向“条带”分布特征,2001—2010 年,NPP 平均值为 102.26 gC m-2 a-1 。 22001—2010 年,疏勒河流域 NPP 总体呈增长趋势,年际波动较大,NPP 明显增加的区域占总面 积 25.15%,明显减小的区域约占 11.93%。 3Hurst 指数分析显示,疏勒河流域 NPP 变化的同向特征强于反向特征,其中持续改 善地区占总面积的 78.3%,21.7%的区域将由改善转为退化。 4在年尺度上,降水是植被 NPP 变化的主要影响因素,NPP 与降 水呈弱的正相关关系,与温度相关性不显著;在月尺度上,温度是 NPP 变化的主要控制因子。 疏勒河流域 NPP 对气候因子不存 在明显的时滞和累积效应。

submitted time 2017-04-11 From cooperative journals:《生态学报》 Hits594Downloads328 Comment 0

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