青海高原国土空间生态保护修复工程气候变化压力分析

李文卿, 詹培元, 张亚男, 杨崇曜, 闫华

自然资源学报 ›› 2024, Vol. 39 ›› Issue (12) : 2819-2833.

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自然资源学报 ›› 2024, Vol. 39 ›› Issue (12) : 2819-2833. DOI: 10.31497/zrzyxb.20241205
生态保护修复与管理

青海高原国土空间生态保护修复工程气候变化压力分析

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Analysis of climate change pressures on ecological protection and restoration projects of territorial space in Qinghai Plateau

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摘要

气候变化是青海高原国土空间生态保护修复工作面临的主要压力之一,然而目前鲜有对该区域生态修复工程气候变化压力的量化分析。聚焦这一问题,基于多源数据,明确1960年以来青海高原的气候变化过程,分析土地覆被类型变化的气候驱动作用,并量化未来气候变化压力。研究发现:青海高原自1960年以来经历了显著的“暖湿化”过程,并呈西部升温快于东部、冬季升温快于夏季的特点。受气候变化的影响,青海高原草地和灌木分布在1980—2020年间呈现普遍扩张趋势,西北局部呈现收缩趋势。气候预测显示,青海高原将面临持续的气候变暖压力,尤其是南部地区。研究结果可为青海高原国土空间生态保护修复工程中相关气候缓解和适应措施的制定提供数据与理论支撑。

Abstract

Climate change is one of the main pressures that the ecological protection and restoration in Qinghai Plateau continues to face, yet there is currently a lack of quantitative analysis of the climate change pressure on ecological restoration projects across this region. Focusing on this issue, this study clarified the climate change process across Qinghai Plateau since 1960, analyzed the driving effects of climate change on the changes in land cover, and quantified the projected future climate change pressures that Qinghai would face during the 21st century, based on multi-source data. We found that Qinghai Plateau has experienced significant warming-wetting trends since 1960, with the change characterized by faster warming in the west than in the east and faster in winter than in summer. Affected by climate changes, the distribution of grass-shrubs in the study area generally expanded from 1980 to 2020, while degraded in the northwest. Climate predictions indicate that Qinghai Plateau is likely to face profound pressures from continued warming trends across the 21st century, especially for the south. Our findings could serve as data and theoretical support for the formulation of relevant climate mitigation and adaptation measures in the ecological protection and restoration projects of territorial space in the plateau.

关键词

青海高原 / 生态保护修复 / 气候变化 / 生态保护修复分区 / 土地覆被变化

Key words

ecological protection and restoration / Qinghai Plateau / climate change / ecological protection and restoration zoning / land-cover change

引用本文

导出引用
李文卿, 詹培元, 张亚男, 杨崇曜, 闫华. 青海高原国土空间生态保护修复工程气候变化压力分析[J]. 自然资源学报, 2024, 39(12): 2819-2833 https://doi.org/10.31497/zrzyxb.20241205
LI Wen-qing, ZHAN Pei-yuan, ZHANG Ya-nan, YANG Chong-yao, YAN Hua. Analysis of climate change pressures on ecological protection and restoration projects of territorial space in Qinghai Plateau[J]. JOURNAL OF NATURAL RESOURCES, 2024, 39(12): 2819-2833 https://doi.org/10.31497/zrzyxb.20241205
自工业革命以来,人类活动的能力和范围都显著增加,在创造巨大社会财富的同时,也深刻改变了地球自然生态环境,并由此引发了气候变化、环境污染、生态系统破坏、生物多样性损失等一系列全球性社会挑战[1,2]。为应对这些挑战,中国加强生态文明建设,推进和落实国土空间规划,统筹山水林田湖草一体化保护修复,全面开展国土空间生态保护修复工作[3]。青藏高原是中国升温速率最快的区域之一,同时也是受气候变化影响最为突出的区域[2,4]。气候变化导致青藏高原冰川退缩,湖泊、湿地面积增加[5,6],局部生态环境发生改变,影响动植物生存和分布[7,8];气候变化还造成部分地区生态环境退化,生态系统不稳定性升高,生物多样性受到威胁,生态脆弱性和生态风险日益加剧[2,9]。气候变化和人类活动成为青藏高原地区国土空间生态保护修复工作面临的主要压力[10]
青海高原位于青藏高原东北部,是世界高海拔地区生物多样性最集中的区域之一,对全球生态系统具有重要的调节作用[2]。有关研究指出,气候变化对青海高原生态系统的影响具有显著的空间差异性和时间变异性[11]。一方面,持续升温缓解了高寒生态系统生长季低温限制,促使青海高原植被覆盖度总体增加,生态系统生产力有所提升,部分区域生态级别由低向高转变[12-15];另一方面,在原本相对干旱的区域,如柴达木盆地等,持续升温进一步加剧水分亏缺,导致草原退化和荒漠化问题愈加严重[16]。快速升温伴随降水量的缓和变化使气候条件逐步突破生态系统生理临界点,升温由缓解低温限制转而加剧水分亏缺,导致对生态系统生产力的促进作用逐步减弱,甚至成为限制因素[17]。研究表明,此类变化已在高海拔或高寒地区广泛发生[18,19],甚至已经造成部分植被群系在其分布边缘出现生产力下降甚至是退化的现象[20]。综上,明确气候变化对敏感生态系统的影响,有助于国土空间生态保护修复工作的有效开展和成效评估。
气候变化对高寒生态系统的影响及其时空变化规律已有广泛研究,然而对于高寒生态保护修复工作面临气候变化压力的量化分析鲜有开展,此类研究可为生态保护修复工程项目的规划、实施和监测提供决策依据,总体提升国土空间生态保护修复的科学化水平。综上,本文通过分析青海高原历史气候变化过程与主要土地覆被类型历史变化的空间相关性,明确气候变化对青海高原高寒生态系统的影响机制及其时空异质规律,并进一步基于气候预测模型量化21世纪内青海高原生态系统保护修复面临的气候变化压力及其区域差异。研究成果可为青海高原国土空间生态保护修复工程气候变化适应和缓解措施的制定提供数据支撑与决策依据。

1 研究方法与数据来源

1.1 研究区概况

青海高原是长江、黄河、澜沧江三江之源,素有“中华水塔”美誉。青海高原地形复杂,平均海拔在4000 m以上,海拔超过3500 m的区域占总面积的70%以上。青海高原地处青藏高原生态屏障区、黄河重点生态区(含黄土高原生态屏障)和长江重点生态区(含川滇生态屏障),是中国重要的生态安全屏障,生态地位突出。综合考虑其生态系统重要性、敏感性和突出生态问题,青海省国土面积的40%以上划定为生态保护红线(图1a黑色阴影),同时划设长江源、黄河源、澜沧江源、祁连山、河湟谷地、共和盆地、青海湖流域和柴达木盆地等8个生态保护修复分区(图1a)。生态保护红线和生态保护修复分区是青海省国土空间生态保护修复工作的基础。
图1 青海省生态保护修复分区和气候环境条件

注:青海省生态修复分区示意来源于《青海省国土空间生态修复规划(2021—2035年)》。

Fig. 1 Ecological protection and restoration zoning and climatic conditions of Qinghai province

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青海高原属于典型的高原高寒大陆性气候。冬季漫长干燥、夏季凉爽湿润,全年超过60%的降水集中在最热的6-8月。研究区年均温由东北向西南逐渐降低,最温暖的河湟谷地和柴达木盆地年均温可达5 ℃以上,而最寒冷的可可西里地区年均温在-8 ℃以下。研究区年均温在0 ℃以下的地区占总面积的2/3以上(图1b)。研究区年降水量大致由东南向西北逐渐递减,大部分地区年降水量在400 mm以下,湿润的东南部地区年降水量超过600 mm,而最干旱的柴达木盆地年降水量在150 mm以下(图1c)。

1.2 数据来源和处理

(1)气候数据
本文使用WorldClim 2.1提供的空间分辨率为2.5'的栅格气候数据表征研究区基准时段和未来气候状况[21],选择气候要素包括年均温和年降水量。WorldClim 2.1提供的1970—2000年全球平均基准气候状况栅格数据是通过对气象站器测数据进行插值和校准创建的。插值过程中考虑了海拔、海陆位置和卫星衍生协变量等因素,大大提高了高分辨率栅格气候数据的精确度和空间可比性。WorldClim 2.1还提供IPCC第五次报告所采用的25个CMIP 6全球气候预测模型(Global Climate Models,GCMs,表1)在四种不同共享社会经济路径(Shared Socioeconomic Pathways,SSPs,1-26,2-45,3-70和5-85,其中1-26,2-45等为预测模式的固定编号)下四个时段内(2021—2040年,2041—2060年,2061—2080年和2081—2100年)的未来气候预测数据。该数据以1970—2000年气候状况为预测基线进行了降尺度和校准(偏差校正)处理。
表1 不同预测情境下涵盖的大气环流模型

Table 1 Global circulation models of climate projections under three Shared Socio-economic Pathways

序号 大气环流模型(GCM) SSP 1-26 SSP 2-45 SSP 5-85
1 ACCESS-CM2
2 ACCESS-ESM1-5
3 BCC-CSM2-MR
4 CanESM5
5 CanESM5-CanOE
6 CMCC-ESM2
7 CNRM-CM6-1
8 CNRM-CM6-1-HR
9 CNRM-ESM2-1
10 EC-Earth3-Veg
11 EC-Earth3-Veg-LR
12 FIO-ESM-2-0
13 GFDL-ESM4
14 GISS-E2-1-G
15 GISS-E2-1-H
16 HadGEM3-GC31-LL
17 INM-CM4-8
18 INM-CM5-0
19 IPSL-CM6A-LR
20 MIROC-ES2L
21 MIROC6
22 MPI-ESM1-2-HR
23 MPI-ESM1-2-LR
24 MRI-ESM2-0
25 UKESM1-0-LL
注:●表示对应模型有数据,○表示对应模型无数据。
研究使用WorldClim 2.1提供的1970—2000年基线气候数据以及在SSP 1-26、SSP 2-45、SSP 5-85三种情境下2041—2060年和2081—2100年两个时段内的气候预测数据描述青海高原在21世纪内的气候变化状况。计算同一预测情境和同一预测时段内25个GCM模型的预测数据平均以减少单一模型带来的预测偏差。本文参照惠特克生物群系(Whittaker's biome-types distribution)[22],以年均温和年降水量为横纵坐标建立气候空间,并依据WorldClim栅格数据建立青海高原在不同时段和预测情境下所占据的气候空间。以WorldClim 2.1提供的1970—2000年气候栅格数据为基准,构建青海高原在1970—2000年间所占据的气候空间作为气候空间基线,并进一步通过栅格分析,计算青海高原在不同预测情境和预测时段预测气候变化幅度。
本文还使用英国东英格利亚大学气候研究所(Climate Research Unit,CRU)提供的空间分辨率为0.5°的月值气候栅格数据(CRU TS 4.05)[23],据此计算1960—2020年间青海高原平均温度、降水量和潜在蒸发量等气候要素的变化趋势。
(2)土地覆被数据
① 2020年青藏高原土地覆被数据:张慧等[7,24]充分利用多源植被分类/土地覆盖分类产品各自的优势,选用集成分类方法,在数据可靠性的基础上遵循一致性的原则,制作了青藏高原2020年现状植被图,在现势性、分类体系的针对性和分类精度上表现优异。数据类型为栅格数据,空间分辨率为250 m。土地覆被类型包括林地(常绿针叶林、针阔叶混交林、常绿阔叶林和落叶阔叶林)、草地、灌丛(郁闭灌丛和稀疏灌丛)、高山植被和其他(无植被地段)。
② 1980年青藏高原土地覆被数据:周继华等[25]采用1980年代青藏高原植被图,使用WorldClim提供的19个生物气候数据,分析生物气候数据与自然植被的关系,确定各类自然植被分布所对应的气候数据变化范围。在此基础上,进一步考虑植被分布地带性规律及其与地形、土壤的关系,依据人工植被周边残存的自然植被、周边地带性植被,对前面的判断结果进行分析,交叉验证人工植被替换结果的准确性。综合以上分析结果,获得近似复原植被图,数据类型为矢量数据。土地覆被类型包括林地(针叶林、针阔叶混交林和阔叶林)、草地(草原、草丛和草甸)、灌丛、高山植被和无植被地段/荒漠。
为最小化两套土地覆被类型分布数据在数据类型和分类体系上的差异对研究结果的潜在影响:① 首先对两套数据进行了栅格化处理,然后统一重采样为空间分辨率0.25°的栅格数据,同时进行了空间坐标校准;② 由于两套数据植被类型分类体系之间的差异主要体现在细分类型上,因此本文选用了森林、草灌(草甸)、裸地(荒漠)和高山植被等四大类型进行分析,并将草地和灌丛合并为草灌类型统一分析,以尽量减小土地覆被类型体系差异造成的误差。通过上述处理后,以0.25°分辨率分别统计各土地覆被类型在相应经纬度上出现扩张或缩减趋势的单元格数量并作可视化,并进一步将土地覆被类型变化与同时期内的气候变化趋势进行叠加分析。
(3)数理统计分析方法
本文基于最小二乘法(Least Squares Method,LSM)拟合建立青海高原气候要素随时间的线性变化模型,计算其变化速率并通过F检验(F-test)验证其显著性;研究栅格分析叠加青海高原气候要素变化趋势及土地覆被类型变化,并通过双样本t检验(two-sample t-test)判断同一土地覆被类型扩张格点和退化格点之间气候要素变化速率差异性的显著程度;使用斯皮尔曼相关(Spearman correlation)分析不同土地覆被类型扩张或退化趋势在空间上的相关关系;使用单要素方差分析(one-way ANOVA)判断不同生态保护修复分区之间气候要素预测变化幅度差异性的显著程度。
最小二乘法(LSM)是一种解决曲线拟合问题常用的数学优化技术,它通过最小化误差的平方和来寻找数据的最佳函数匹配。斯皮尔曼相关分析是一种非参数统计方法,用于衡量两变量之间的相关关系强度和方向,分别对两个变量XY做秩变换,用 RX RY表示,然后计算秩变量 RX RY之间的皮尔逊相关系数,其计算公式如式(1)。方差分析(ANOVA)常用于检验多个样本平均值之间差异性的显著程度,分析步骤包括计算总偏差平方和(SSt)、组间偏差平方和(SSb)、组内偏差平方和(SSw)、组间均方(MSb)、组内均方(MSw)和F值,并通过F值与临界值的比较来进行假设检验。
rhoρ=rRX, RY=cov(RX, RY)σRXσRY
(1)
式中:rho为斯皮尔曼相关系数; r为秩变量之间的皮尔逊相关系数; cov(RX, RY) 代表秩变量 RX RY的协方差;σR代表秩变量 RX RY的标准差。
以上数据处理、数理统计分析以及研究结果的可视化均通过R语言(version 4.3.2)[26]实现,部分空间分析和空间可视化通过ArcGIS平台实现。

2 结果分析

2.1 青海高原1960—2020年气候状况变化及其时空异质特征

本文计算了青海高原主要气候要素在1960—2020年间的变化趋势(图2)。结果显示,研究区自1960年以来经历了普遍的显著升温过程,平均升温速率达到每十年0.19 ℃(℃ dec-1,adjusted-R2 = 0.46,p<0.0001,图2a)。在空间上,升温速率由西北部的>0.3 ℃ dec-1逐步递减至东南部的<0.1 ℃ dec-1,最高升温速率出现在海西蒙古族藏族自治州西北部,最低升温速率出现在果洛藏族自治州南部。相较于普遍的快速升温,研究区过去60年的降水量变化趋势相对和缓,平均每十年增加7.1 mm(mm dec-1,adjusted-R2 = 0.22, p<0.001,图2b)。自1960年以来,研究区东部年降水量增加速率超过10 mm dec-1 p<0.05),而西部降水量在同时期内未出现明显变化(p>0.05)。潜在蒸发量方面,研究区平均潜在蒸发量表现出显著的增加趋势,但平均增速仅为2.7 mm dec-1(adjusted-R2 = 0.09,p=0.012,图2c),从空间上看,研究区大部分地区潜在蒸发量并未表现出显著的变化趋势(p>0.05)。
图2 1960—2020年青海高原气候变化趋势

Fig. 2 Annual climate changes across Qinghai Plateau during 1960-2020

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研究区气候变化趋势表现出显著的季间差异性(图3)。1960年以来,冬季均温以平均0.31 ℃ dec-1的速率显著提升(adjusted-R2 = 0.30,p<0.0001,图3a4),远高于年均温以及春夏秋三季均温的升高速率(0.18 ℃ dec-1、0.18 ℃ dec-1和0.14 ℃ dec-1图3a1~图3a3)。相比之下,近60年来,研究区降水量增加主要发生在春季和夏季,平均增速分别为 1.7 mm dec-1和3.8 mm dec-1p<0.01),占全年降水量增速的77.5%(图3b1图3b2)。冬季降水量增速仅为0.2 mm dec-1(adjusted-R2 = 0.12,p=0.0035,图3b4),而秋季降水并未表现出显著的变化趋势(p>0.05,图3b3)。研究区夏秋冬三季潜在蒸发量均未表现出显著的变化趋势(p>0.05),仅春季的潜在蒸发量呈现速率为1.4 mm dec-1(adjusted-R2 = 0.09,p<0.05)的显著升高趋势(图3c1~图3c4)。
图3 1960—2020年青海高原季节气候变化趋势

Fig. 3 Seasonal climate changes across Qinghai Plateau during 1960-2020

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综上所述,自1960年以来,青海高原经历了显著的快速升温过程,同时降水量有缓和增加,而潜在蒸发量变化有限,总体呈现“暖湿化”变化趋势。此外,研究区气候变化表现出显著的空间异质性和季间差异性。

2.2 青海高原1980—2020年主要土地覆被类型变化及其与气候变化的关系

研究发现,1980—2020年间,研究区森林分布仅出现零星下降趋势,在其主要的森林分布区祁连山地区,森林分布并未出现显著变化(图4a)。相较而言,草地和灌木分布则在1980—2020年间出现了区域性的显著变化(图4b)。研究区草灌分布总体呈扩张趋势,气候条件的“暖湿化”改善可能是其主要自然驱动因素,而近年来青海省实施的生态保护措施也可能发挥了关键作用。分析显示,1980—2020年间,研究区草灌分布扩张区域年均温升高和降水增加速率均显著高于草灌分布出现退化的区域(t-test,p<0.0001)。此外,草灌分布呈现扩张趋势的区域多在生态保护红线内(70%),退化区域则多在生态保护红线之外(87%)(图4b)。尽管研究区草灌分布呈现普遍扩张趋势,但柴达木盆地和河湟谷地出现了明显的集聚性草灌收缩(图4b),这可能与采矿以及城镇扩展等人为活动因素有关;此外,以柴达木盆地为代表的干旱区,降水量的有限增加可能无法抵消快速升温造成的额外潜在蒸发量,从而出现局部的“暖干化”趋势(图2),这可能是区域草灌木分布呈现收缩和退化趋势的自然驱动因素。
图4 1980—2020年青海高原主要土地覆被类型变化

Fig. 4 Changes in land cover across Qinghai Plateau from 1980 to 2020

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青海高原裸地或荒漠分布变化在区域上与草灌分布变化呈现显著的空间负相关关系(Spearman相关,rho = -0.417,p<0.0001,图4b图4c),新增裸地可能来源于由草灌生态系统退化;受气候变化和生态恢复工程的共同正向驱动,草灌分布也出现向其非地带性区域扩展的趋势,如共和盆地、祁连山地区以及唐古拉山地区等(图4)。青海高原高山植被分布在过去60年呈现普遍性的收缩或退化趋势(图4d),由于高山植被多为耐寒物种,对气候变化的脆弱性和敏感性较强,因此,气候暖化可能是研究区高山植被分布收缩或退化的主要驱动因素。

2.3 青海高原未来气候变化以及生态保护修复分区之间的差异

本文构建了青海高原1970—2000年间的年均温—年降水基线气候空间。参照Whittaker植物群系,研究区属于高寒植物群系[22]图5)。由图6可见,研究区在21世纪内将经历持续升温过程。在SSP 2-45预测情境下,到21世纪末(2081—2100年),研究区年均温将由1970—2000年间的-2.18 ℃上升至1.76 ℃;而在SSP 5-85预测情境下,研究区年均温甚至将升高至4.71 ℃,平均升温幅度达到6 ℃以上。伴随显著的预测升温过程,到2080—2100年,在SSP 2-45和SSP 5-85情境下,研究区平均年降水量将由1970—2000年间的320 mm分别增加至363 mm和390 mm(图6)。根据气候模型预测和Whittaker植物群系分类,青海高原未来气候条件可能逐步接近温带气候(图5a),这一变化可能导致青海高原高寒生态系统在21世纪内遭遇温带物种的入侵。
图5 惠特克生物群系划分示意及青海高原1970—2000年气候空间基线和未来变化状况

Fig. 5 The Whittaker's biome-types distribution and the near current (1970-2000) climate space occupied by Qinghai Plateau

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图6 青海高原气候空间未来变化状况

Fig. 6 The projected future climate spaces occupied by Qinghai Plateau

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通过计算青海高原在多预测情境(SSP 1-26、SSP 2-45和SSP 5-85)下和多预测时间段(2041—2060年和2081—2100年)内年均温和年降水量的变化幅度(ΔMAT和ΔMAP)发现,到21世纪末(2081—2100年),在所有预测情境下,研究区都将经历普遍的气温升高和降水量增加(图7)。其中,在相对乐观的SSP 1-26预测情境下,研究区到2100年前的升温幅度将被控制在1~3 ℃(图7a1图7a4),接近《巴黎协定》对全球平均升温幅度的要求;而在相对悲观的SSP 5-85预测情境下,研究区年均温升高幅度将达到6 ℃以上,部分地区(西南部分)甚至达到7 ℃以上(图7a6);即便在相对温和的SSP 2-45预测情境下,研究区到2100年前的升温幅度都将在4 ℃以上(图7a5)。从空间上看,温度升高和降水增加幅度均出现由东北至西南逐渐升高的趋势,最大值均出现在玉树藏族自治州和果洛藏族自治州(图7)。总体而言,青海高原南部高海拔相对寒冷湿润的区域相较于北部低海拔相对温暖干旱的区域,变暖变湿趋势将更加显著。
图7 青海高原气候要素预测变化

Fig. 7 Predicted changes in climate for Qinghai Plateau

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研究进一步发现,青海省不同生态保护修复分区的气候变化幅度表现出显著的差异性(one-way ANOVA,p<0.0001,图7图8)。气候模型显示,在所有预测情境下,位于研究区南部的澜沧江源、长江源和黄河源生态修复分区年均温和年降水预测升高幅度均显著高于青海高原平均水平(t-test,p<0.0001,图8a);位于东北部地区的河湟谷地、青海湖流域、共和盆地和祁连山等生态修复分区预测升温幅度显著低于青海高原平均水平(t-test,p<0.0001,图8a),而预测降水增加幅度与全域平均水平相近(图8b);位于西北部面积最大的柴达木盆地生态修复分区预测升温幅度与青海高原平均水平相近(图8a),而其预测降水增加幅度显著低于全域平均水平(t-test,p<0.0001,图8b)。生态修复分区之间气候变化幅度的差异意味着生态保护修复工程面临不同的气候变化压力。此外,青海省生态保护红线内相较于生态保护红线外的气候变化幅度普遍更高(图7),凸显青海高原生态保护修复工作面临的气候变化压力。
图8 青海省生态保护修复分区气候要素预测变化

Fig. 8 Predicted changes in climate for ecological protection and restoration zones of Qinghai province

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3 结论与讨论

3.1 结论

本文聚焦青海高原国土空间生态保护修复面临的气候变化压力这一关键问题,基于多源气候数据,量化分析1960年以来青海高原气候条件的历史变化过程及其时空异质特征,分析主要土地覆被类型变化的气候驱动作用,进而基于气候预测模型,分析2100年以前青海高原面临的持续性气候变化过程以及不同生态保护修复分区之间的差异。
研究发现:(1)自1960年以来,青海高原经历了显著的“暖湿化”过程,并且表现出显著的空间异质性和季间差异性;(2)1980—2020年,青海高原草灌分布呈现普遍的扩张趋势,且草灌分布的扩张区域的年均温升高和降水增加速率均显著高于草灌分布的退化区域,证明了气候“暖湿化”的驱动作用;(3)气候模型预测青海高原在21世纪内还将经历显著的升温过程,而快速升温伴随相对缓和的降水量增加可能导致潜在蒸发的快速升高,逆转过去60年的“暖湿化”趋势,从而使高寒植被面临潜在的水分亏缺限制;(4)青海省不同生态保护修复分区的未来气候变化存在显著差异,这意味着生态保护修复工作面临的气候变化压力不同,强调了在相关生态保护修复工作开展过程中,制定因地制宜的气候变化应对和适应措施的必要性。

3.2 讨论

3.2.1 青海高原生态保护修工程面临显著且时空异质的气候变化压力

受气候变化和人类活动的长期干扰,青海高原生态保护修复工作面临生态本底脆弱、生态系统质量偏低、生态系统退化严重、农牧业用地矛盾突出、气候变化导致的生态风险增加等问题。相关研究指出,气候变化是高寒生态系统面临的主要自然威胁,因此,量化高寒生态系统面临的气候变化压力,可以为相关生态保护修复工作的开展和政策制定提供理论与数据支持。明确气候变化对国土空间生态保护修复工作的压力及其时空变化,是有效开展相关工作的基础[10]。青藏高原是过去几十年全球升温最快的区域之一,由于高寒生态系统的脆弱性以及对环境变化的敏感性,青海高原生态系统受气候变化的影响显著,充分强调了针对青海高原国土空间生态保护修复面临气候压力开展量化分析的必要性和紧迫性[2]
过去60年,青海高原气候“暖湿化”趋势明显,在空间上,青海高原西部较东部升温更快、降水增加更缓;在时间上,青海高原冬季较夏季升温更快、降水增加更缓。气候变化可能导致高原地区积雪面积减少、冰川持续退缩,以及多年冻土退化,进一步造成江河源区冰川退缩,削弱生态系统水源涵养功能和生物多样性维持功能[5,14]。气候变化背景下,生态系统稳定性降低,水土流失、冰湖溃决、洪涝、泥石流等灾害风险增加,部分区域出现退化加剧的现象;部分湖泊水位上升,湖畔牧场淹没、湖泊水环境污染[6];同时,气候变化造成极端气候事件增加[16],引发植物群落结构和功能发生根本性改变,造成相应植被逆行性演替,以至物种多样性丧失等严重生态问题[7,14]。以上不仅对青海高原国土空间生态保护修工程的项目实施和成效造成严峻挑战,更要求决策者在工程设计阶段制定更具针对性和行之有效的气候变化适应与缓解措施。

3.2.2 青海高原植被变化的气候和人类活动驱动因素

土地覆被类型的变化揭示了自然生态系统对气候变化的响应,以及人类活动对生态系统的干预[7]。受人类活动(采矿业发展和城镇化进程)和气候变化的影响,以及生态保护修复举措产生的积极效应,青海高原植被分布自1980年以来发生显著变化[13,27],在生态保护修复具体措施制定的过程中,需要充分考虑和认识到这一变化。草灌分布扩张区域多出现在青海省生态保护红线内,这一现象可以作为生态保护修复举措取得显著成效的具体证据。相较而言,青海高原森林分布未发生显著变化,这可能主要得益于森林保护措施的落实以及森林生态系统相较于高寒草地生态系统更强的稳定性和抗逆性。
青海高原植被覆盖虽然总体上呈增加趋势,但对于复杂脆弱的高寒生态系统而言,这并不一定能完全抵消气候变化带来的负面影响[17,28],尤其是考虑到IPCC模型一致预测研究区在21世纪内将遭受持续性增温趋势的冲击。例如,受人类活动以及局部气候“暖干化”趋势的影响,柴达木盆地和河湟谷地区域的草地出现了明显的集聚性收缩。已有研究指出,气候持续变暖缓解了高海拔和高纬度地区的低温限制,在促进本地生态系统生产力提升的同时[13,15],也为毗邻温带物种提供了适宜的生存环境,促使相应植物群系向更高纬度和更高海拔迁徙[29-31],对本地高寒生态系统带来显著竞争压力,威胁高寒生态系统的未来存续。具有更强繁殖能力的温带物种将对高寒物种形成竞争优势,并威胁其存续。如在北半球广泛出现的高山树线抬升、寒温带针叶林侵入北极苔原地区、温带—寒温带生态系统交错带物种组成和群落结构发生显著变化等[30,32]。同样,类似过程已在青藏高原地区得到广泛报道[33-35]
综合青海高原高寒生态系统稳定性较低以及对气候变化脆弱敏感的特点,以上因素均要求决策者在制定并实施生态保护修复具体工作的过程中,应充分考虑缓解和适应气候变化的具体措施以保证生态保护修复工程成效,比如积极运用基于自然的解决方案(Nature-based Solutions)等国际前沿理念和技术方法[36]。此外,本文也存在一定的局限性:一是土地覆被变化分析可能受到数据来源和土地覆被分类体系差异的影响,未来的研究可以通过更高分辨率和更精确的遥感数据来提高分析的准确性;二是气候变化对生态系统的影响是一个长期和动态的过程,需要持续的监测和研究来更好地理解其复杂性,以便为生态保护修复提供持续性理论和数据支撑。

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摘要
针对全球变化影响下的国土空间和生态系统,生态文明建设和国土空间规划是中国在新时代的积极响应,国土整治与生态修复的转型和提升成为必然要求。在介绍国土整治与生态修复概念内涵的基础上,指出中国国土空间生态环境问题的复杂性和生态文明建设的新理念要求决定了国土整治与生态修复的转型。从工作理念、理论基础、技术体系和制度建设等方面,分析了当前国土整治与生态修复工作中存在的不足,主要包括整体综合理念滞后、理论基础体系欠缺、技术支撑相对薄弱、体制机制不尽完善等方面。针对这些不足,提出了新时代国土整治与生态修复转型的路径和策略,主要策略包括强化系统思维、提升理论体系、加强技术支撑、完善机制建设等内容,以期为国土整治与生态修复推进美丽中国建设提供科学依据。
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As the national land space and ecosystems are affected by global change nowadays, ecological civilization construction and land spatial planning must be the positive responses of China in the new era. Great achievements have been made in the restorations of ecological space and ecosystems through projects for land consolidation and ecological restoration. However, the degradation of some regional ecosystems still exists, and the interference of unreasonable traditional human activities has not been completely eliminated in China. Meanwhile, China faces a large number of challenges in the economic and social developments of the new era. The transformation and improvement of land consolidation and ecological restoration therefore become the inevitable requirement. Through introducing the concepts, connotations of land consolidation, ecological restoration and relationships between them in the new era, this paper suggested that the transformation should be determined by the variations and complexities of regional ecological and environmental issues, the new requirements of ecological civilization construction and land spatial planning. We also indicated the four shortcomings of land consolidation and ecological restoration at present, including working perception, theoretical basis, technological system, and institutional construction. Specifically in recent practices, the integrated and comprehensive concepts are lagging behind, the key theoretical systems are deficient, the technological supports are instable, and the related institutions are insufficient. Therefore, we proposed the strategies for the corresponding transformation, which mainly included: (1) intensifying the systematic thinking and concept to promote the implementation of land consolidation and ecological restoration on a regional basis; (2) upgrading the theoretical system to stimulate the new motivation for land consolidation and ecological restoration; (3) enhancing the technical support to improve the effectiveness of land consolidation and ecological restoration works; (4) improving the institution construction to reinforce the support foundation for land consolidation and ecological restoration implementations.

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王军, 张骁, 高岩. 青藏高原植被动态与环境因子相互关系的研究现状与展望. 地学前缘, 2021, 28(4): 70-82.
摘要
青藏高原是中国乃至全球对气候变化最敏感的地区之一,是全球平均海拔最高的地理单元,对周边地区起到重要的生态安全屏障作用。近年来,当地植被受到气候变化和人类活动的双重压力。本文基于文献检索分析青藏高原的植被生理、生态特征对气候变化和人为干扰的响应,并利用荟萃分析定量综述植被覆盖度变化对土壤理化性质的影响。在此基础上分析青藏高原植被与环境因子相互关系的研究尺度与方法。结果表明:(1)气温、降水、辐射等自然因素和放牧、农耕、筑路等人为活动均对青藏高原植被的碳交换、水分利用效率、元素含量与分布格局、物候、多样性等指标产生显著影响,植被的变化也同时影响着土壤的水热交换、水文过程和理化性质等;(2)在植被退化过程中,由高覆盖度向中覆盖度转变时对土壤理化性质产生的不利影响强于由中覆盖度转为低覆盖度时,高覆盖度地区的植被保护需要引起更多关注;(3)现有研究更多关注单一要素、单一尺度,未来应关注多要素间的相互耦合,通过合作与共享获取数据,开展多尺度对比和尺度效应研究,系统梳理和分析植被与环境因子的相互关系可为制定科学合理的生态修复策略提供科学依据。
[WANG J, ZHANG X, GAO Y. The relationships between vegetation dynamics and environmental factors on the Qinghai-Tibet Plateau: A review of research progress and prospect. Earth Science Frontiers, 2021, 28(4): 70-82.]

The Qinghai-Tibet plateau is one of the regions most sensitive to climate change both in China and in the world at large. In recent years, local vegetation has been under the dual pressure from climate change and human activities. Its physiological and ecological characteristics, in response to climate change and human interference, were analyzed in this paper based on literature research, and the impact of change in vegetation coverage on soil physical and chemical properties were quantitatively summerized based on meta-analysis. On this basis, this paper reviewed the research scales and methods in studying the relationship between vegetation and environmental factors on the Qinghai-Tibet plateau and summerized the results as the follows: 1) Natural factors such as temperature, precipitation and radiation, and human activities such as grazing, farming and road construction, significantly affected the carbon exchange, water use efficiency, elemental content and distribution pattern, phenological period and diversity of vegetation. The change of vegetation also affected the water heat exchange, hydrological process and physical and chemical properties of soil. 2) In the process of vegetation degradation, the changes in vegetation coverage from high to medium had a stronger negative effect on the physical and chemical properties of soil than changes from medium to low; therefore, more attention should be paid to vegetation protection in the high coverage area. 3) Previous researches mainly focused on the impact of a single factor and a single scale. In future, more attention should be paid to multi-factor coupling by considering the intra- and out-of-domain effects on the ecosystem. Besides, multi-scale comparison and scale-effect research should be conducted to explore the ecological restoration strategies and climate change coping mechanisms at different scales based on data compiled through cooperation and data sharing. To implement further research, it is also necessary to integrate multi-source, multi-point, long-term series monitoring data to establish an observational network covering the whole Qinghai-Tibet plateau. In addition, data sharing should be strengthened to save research resources while reducing damage caused by unnecessary repeated sampling to the fragile plateau ecosystem. The systematic review of the relationships between vegetation and environmental factors could be applied to the planning, design and monitoring of ecological protection and restoration projects, so as to develop the ecological protection and restoration technology and management system suitable for the Qinghai-Tibet plateau region, and also provide support for policy-making in this region.

[9]
刘飞, 刘峰贵, 周强, 等. 青藏高原生态风险及区域分异. 自然资源学报, 2021, 36(12): 3232-3246.
摘要
全球变化背景下,青藏高原生态系统受到自然、人为双重影响和威胁,生态风险日益加剧。针对生态风险源、脆弱性以及风险管理能力选取30个评估指标,利用生态风险评估优化模型,综合评估了青藏高原的生态风险,并得出如下结论:青藏高原生态风险总体处于较低水平,以低和极低生态风险为主,共占研究区面积的55.84%;极高风险主要分布在北部高山和极高山地区,中等风险主要分布在高原北部以及高原的西部和西南部地区,中、高生态风险在空间分布上形成一个“C”字形结构;青藏高原生态风险整体受自然主导因子控制,人为对生态环境的影响不容忽视,协调和降低青藏高原人类活动区域人类对生态环境的影响,是今后规避生态风险的重要途径。
[LIU F, LIU F G, ZHOU Q, et al. Ecological risk and regional differentiation in the Qinghai-Tibet Plateau. Journal of Natural Resources, 2021, 36(12): 3232-3246.]

Under the background of global change, the ecosystem of the Qinghai-Tibet Plateau has been affected and threatened by both nature and human activities, and the ecological risks are intensifying. The Qinghai-Tibet Plateau is a relatively independent geographic unit with a high average altitude and complex and diverse landforms. Its fragile alpine ecosystem is extremely sensitive to global climate change. In recent years, the population of the plateau has increased and the process of urbanization has accelerated, the scale and intensity of human activities have increased significantly, and ecological risks have increased. At present, the research results of ecological risk assessment are mainly found in local areas of the Qinghai-Tibet Plateau. This article, aiming at understanding the source of ecological risks, analyzes the spatial distribution of risks and their causes. The ecological risk assessment of the entire plateau is expected to provide references for the identification, management and early warning of regional ecological risks. We establish an ecological risk assessment index system for the study area, which includes 13 ecological risk source indicators, 10 ecological vulnerability indicators, and 7 ecological risk management capability indicators. Then we select the official remote sensing product data with a high spatial resolution, according to the characteristics of the data which are divided into numerical and non-numerical data. Using ArcGIS 10.2 to normalize the numerical data, according to the contribution rate to ecological risk, the non-numerical data are graded, and the ecological risk evaluation optimization model is used to comprehensively evaluate the ecological risk of the plateau. The results showed that: overall ecological risk of the study area is relatively low, with low and very low ecological risk areas accounting for 55.84%, extremely high risk areas being only 7.19%, high risk areas 11.95%, and medium ecological risk areas 25.02%, and the extremely low and low ecological risk areas account for more than half of the plateau area; medium ecological risk areas are mainly distributed in areas with high intensity of human activities. The impact of human activities on the eco-environment of the Qinghai-Tibet Plateau cannot be ignored; the extremely high-risk areas and medium-risk areas form a "C"-shaped pattern; the low-risk areas in the hinterland of the plateau have higher altitudes, severe cold climates, and fragile eco-environments, but the strengthening of ecological management measures has greatly reduced the ecological risk in the study area. The overall ecological risk of the Qinghai-Tibet Plateau is mainly controlled by natural factors, and the impact of human activities on the eco-environment cannot be ignored. The establishment of national nature reserves or national parks to protect the ecological environment can greatly reduce its ecological risks. It is necessary to pay special attention to areas with high intensity of human activities on the plateau, where their ecological risks have reached a medium intensity. Creating a new pattern of harmonious coexistence between humans and nature, and avoiding excessive human intervention in the eco-environment on the Qinghai-Tibet Plateau is an important way to reduce ecological risks in the future.

[10]
LIU X X, ZHAO W W, YAO Y, et al. The rising human footprint in the Tibetan Plateau threatens the effectiveness of ecological restoration on vegetation growth. Journal of Environmental Management, 2024, 351: 119963, Doi: 10.1016/j.jenvman.2023.119963.
[11]
李林, 李晓东, 校瑞香, 等. 青藏高原东北部气候变化的异质性及其成因. 自然资源学报 2019, 34(7): 1496-1505.
摘要
利用1961-2016年西宁等青藏高原东北部13个气象台站气温、降水等气象资料以及国家气候中心发布的南海季风指数、西伯利亚高压指数等大气环流特征量数据,分析近56年来气候变化与高原主体的差异性及其可能的气候成因。研究表明:近56年来青藏高原东北部气候变暖趋势十分显著,年平均气温气候倾向率高达0.39 ℃/10 a,呈现出三次明显的阶梯性增高态势,并于1994年前后发生了由冷到暖的突变,同时具有明显的空间差异性;年降水量及四季降水量均没有明显变化趋势,虽然经历了2002年左右由少到多的变化,但并未出现明显突变,年降水量具有3年、5年的准周期,而年降水日数微弱减少,降水强度呈增加趋势;该区域气候变化的年际波动主要受到东亚季风、高原季风和南海季风的年际振荡及其相互作用的影响,而西风环流的作用并不明显,植被覆盖的恢复既是对2002年以来降水量增加的具体反应,同时也对于气候变暖趋势起到了一定的缓和作用。
[LI L, LI X D, XIAO R X, et al. The heterogeneity of climate change and its genesis in the Northeastern Qinghai-Tibet Plateau. Journal of Natural Resources, 2019, 34(7): 1496-1505.]
The northeastern part of Qinghai-Tibet Plateau is situated in the transitional zone of the Qinghai-Tibet Plateau and Loess Plateau. Known as Qinghai's Hehuang areas, it is the valleys of Yellow River and Huangshui River. And it is the birthplace of civilization and cradle of economic and social development of the Qinghai-Tibet Plateau, especially Qinghai province. It is also one of the areas of earliest human activities in the Yellow River Basin. Because it is located in the intersection of China's two high plateaus, its climate and its changes have a certain heterogeneity. The northeastern part of Qinghai-Tibet Plateau has some characteristics of the East Asian monsoon climate, which is different from complete plateau continental climate. Therefore, due to complexity of its climate change and significance of its impact on economy and society, the issue of climate change in the region has received wide attention from academic community. Based on analysis of climate change in the northeastern part of Qinghai-Tibet Plateau from 1961 to 2016 and its heterogeneity in climate change over the Qinghai-Tibet Plateau, this paper discusses the causes of climate change from evolution of atmospheric circulation and changes in vegetation cover. The meteorological data such as temperature, precipitation and other meteorological data of 13 meteorological stations in the northeastern Qinghai-Tibet Plateau from 1961 to 2016, the data of atmospheric circulation characteristics such as the South China Sea summer monsoon index and Siberian High Index released by the National Climate Center were analyzed in this paper. And, the heterogeneity between climate change and plateau main body and their possible climate genesis were also analyzed in the past 56 years. The results are shown as follows: (1) Climate warming trend in the northeastern part of Qinghai-Tibet Plateau is very significant in the past 56 years. The climatic tendency rate of annual average temperature is as high as 0.39 °C/10 a, showing three obvious stepwise increases and it has mutations from cold to warm around 1994 with significant spatial variability. (2) There is no obvious change in annual and seasonal precipitation. Although it has experienced less to more changes around 2002, there is no significant mutation. The annual precipitation has a quasi-periodic variations of 3 years and 5 years, while the number of annual precipitation days is slightly reduced and precipitation intensity is increasing. (3) The interannual variability of climate change in this region is mainly affected by interannual oscillations of East Asian monsoon, plateau monsoon and South China Sea monsoon and their interactions, while effect of westerly circulation is not obvious. The restoration of vegetation cover has not only responded to precipitation increase since 2002 but also played a certain role of mitigative effect in climate warming trend.
[12]
陈舒婷, 郭兵, 杨飞, 等. 2000—2015年青藏高原植被NPP时空变化格局及其对气候变化的响应. 自然资源学报, 2020, 35(10): 2511-2527.
摘要
全球变化背景下,青藏高原作为我国乃至全球气候变化的“天然实验室”,植被生态系统发生了深刻变化。引入重心模型等方法分析和探讨2000—2015年青藏高原植被NPP时空变化格局及其驱动机理,并定量区分NPP变化过程中气候变化和人类活动的相对作用。研究发现:(1)2000—2015年,青藏高原植被NPP年均值总体上呈现从东南向西北递减的趋势。在年际变化方面,近16年植被NPP呈现波动上升趋势,其中在2005年出现上升陡坡,并在2005—2015年表现为高位波动的态势。(2)青藏高原植被NPP增加区(变化率>10%)主要集中于三江源地区、横断山区北部、雅鲁藏布江中下游以及那曲地区的中东部,而植被NPP减小区(变化率<-10%)则主要分布于雅鲁藏布江上游和阿里高原。(3)近16年青藏高原植被NPP重心总体向西南方向移动,表明西南部植被NPP在增量和增速上大于东北部。(4)青藏高原植被NPP与气候因子相关性的地区差异显著,其中植被NPP与降水显著相关的区域主要位于青藏高原中部、青藏高原东南部及雅鲁藏布江流域中下游,而植被NPP与气温显著相关的区域主要位于藏南地区、横断山区北部、青藏高原中部和北部。(5)气候变化和人类活动在青藏高原植被NPP变化过程中的相对作用存在显著的时空差异性,在空间上呈现“四线—五区”的格局。研究成果能够为揭示青藏高原区域生态系统对全球变化的响应机制提供理论和方法支撑。
[CHEN S T, GUO B, YANG F, et al. Spatial and temporal patterns of NPP and its response to climate change in the Qinghai-Tibet Plateau from 2000 to 2015. Journal of Natural Resources, 2020, 35(10): 2511-2527.]
[13]
丁明军, 张镱锂, 刘林山, 等. 1982—2009年青藏高原草地覆盖度时空变化特征. 自然资源学报, 2010, 25(12): 2114-2122.
摘要
利用GIMMS和SPOT VGT两种归一化植被指数(NDVI)数据对青藏高原地区1982&mdash;2009年期间草地覆盖的时空变化进行研究,结果如下:①青藏高原草地植被覆盖的年际变化存在着显著的空间差异。趋于升高的区域主要分布在西藏的北部和新疆的南部;趋于下降的地区主要分布在青海的柴达木盆地、祁连山、共和盆地、江河源地区及川西地区。②青藏高原草地覆盖度年际变化趋势分析表明,在90%的显著性检验水平上,降低和增加面积的比率为0.31,草地植被覆盖水平总体趋于升高态势。③以10 a为步长的分析表明:草地盖度呈现持续增加的区域主要分布在西藏北部;阿里地区草地盖度表现为先减少后增加;雅鲁藏布江流域草地盖度呈现先增加而后减少;而持续减少的区域主要分布在青海省以及川西地区,其中青海省分布最广;统计结果显示,高原大部分地区草地盖度具有升高的态势。
[DING M J, ZHANG Y L, LIU L S, et al. Temporal and spatial distribution of grassland coverage change in Tibetan Plateau since 1982. Journal of Natural Resources, 2010, 25(12): 2114-2122.]
[14]
杨亮, 刘丽男, 孙少波. 1982—2015年青藏高原植被变化的主导环境因子. 生态学报, 2023, 43(2): 744-755.
[YANG L, LIU L N, SUN S B. The dominated environmental factors of vegetation change on the Qinghai-Tibet Plateau from 1982 to 2015. Acta Ecologica Sinica, 2023, 43(2): 744-755.]
[15]
刘旻霞, 焦骄, 潘竟虎, 等. 青海省植被净初级生产力(NPP)时空格局变化及其驱动因素. 生态学报, 2020, 40(15): 5306-5317.
[LIU M X, JIAO J, PAN J H, et al. Spatial and temporal patterns of planting NPP and its driving factors in Qinghai province. Acta Ecologica Sinica, 2020, 40(15): 5306-5317.]
[16]
贾艳青, 张勃. 1960—2016年中国北方地区极端干湿事件演变特征. 自然资源学报, 2019, 34(7): 1543-1554.
摘要
基于中国北方地区424个气象站点1960-2016年的日气象数据础,应用FAO Penman-Monteith模型计算潜在蒸散(ET<sub>0</sub>),基于降水量和潜在蒸散计算湿润指数,对湿润指数进行标准化后统计极端干湿事件频率,分析极端干湿事件频率的空间变化趋势、多时间尺度演变特征以及ENSO事件对极端干湿事件变化趋势的影响。结果表明:北方极端干旱和极端湿润事件频率分别呈显著下降和显著上升趋势,年际倾向率分别为-0.10次/10年和0.13次/10年。空间上,极端干旱频率整体呈减少趋势,包括青藏高原、西北和东北地区。西北极端干旱频率减少速率较大,青藏高原中部、新疆北部和东北北部部分站点极端湿润频率增加幅度较大。各年代中,华北极端干旱多发,东北和青藏高原极端湿润多发。季节上,分区极端干旱发生概率均大于极端湿润发生概率,华北极端干旱发生概率最高,青藏高原极端湿润发生概率最高。ENSO与湿润指数存在滞后性的关系。El Niño翌年,气候偏湿润的年份较多;La Nina翌年,气候偏干旱的年份较多。SSTA与翌年湿润指数在年际和夏季两个时间尺度上存在显著的正相关关系。
[JIA Y Q, ZHANG B. Spatio-temporal changes of the extreme drought and wet events in Northern China from 1960 to 2016. Journal of Natural Resources, 2019, 34(7): 1543-1554.]
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Larch, a widely distributed tree in boreal Eurasia, is experiencing rapid warming across much of its distribution. A comprehensive assessment of growth on warming is needed to comprehend the potential impact of climate change. Most studies, relying on rigid calendar-based temperature series, have detected monotonic responses at the margins of boreal Eurasia, but not across the region. Here, we developed a method for constructing temporally flexible and physiologically relevant temperature series to reassess growth-temperature relations of larch across boreal Eurasia. Our method appears more effective in assessing the impact of warming on growth than previous methods. Our approach indicates widespread and spatially heterogeneous growth-temperature responses that are driven by local climate. Models quantifying these results project that the negative responses of growth to temperature will spread northward and upward throughout this century. If true, the risks of warming to boreal Eurasia could be more widespread than conveyed from previous works.© 2023. The Author(s).
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LIU H Y, PARK WILLIAMS A, ALLEN C D, et al. Rapid warming accelerates tree growth decline in semi-arid forests of Inner Asia. Global Change Biology, 2013, 19(8): 2500-2510.
Forests around the world are subject to risk of high rates of tree growth decline and increased tree mortality from combinations of climate warming and drought, notably in semi-arid settings. Here, we assess how climate warming has affected tree growth in one of the world's most extensive zones of semi-arid forests, in Inner Asia, a region where lack of data limits our understanding of how climate change may impact forests. We show that pervasive tree growth declines since 1994 in Inner Asia have been confined to semi-arid forests, where growing season water stress has been rising due to warming-induced increases in atmospheric moisture demand. A causal link between increasing drought and declining growth at semi-arid sites is corroborated by correlation analyses comparing annual climate data to records of tree-ring widths. These ring-width records tend to be substantially more sensitive to drought variability at semi-arid sites than at semi-humid sites. Fire occurrence and insect/pathogen attacks have increased in tandem with the most recent (2007-2009) documented episode of tree mortality. If warming in Inner Asia continues, further increases in forest stress and tree mortality could be expected, potentially driving the eventual regional loss of current semi-arid forests. © 2013 John Wiley & Sons Ltd.
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CRU TS (Climatic Research Unit gridded Time Series) is a widely used climate dataset on a 0.5° latitude by 0.5° longitude grid over all land domains of the world except Antarctica. It is derived by the interpolation of monthly climate anomalies from extensive networks of weather station observations. Here we describe the construction of a major new version, CRU TS v4. It is updated to span 1901-2018 by the inclusion of additional station observations, and it will be updated annually. The interpolation process has been changed to use angular-distance weighting (ADW), and the production of secondary variables has been revised to better suit this approach. This implementation of ADW provides improved traceability between each gridded value and the input observations, and allows more informative diagnostics that dataset users can utilise to assess how dataset quality might vary geographically.
[24]
张慧, 赵涔良, 朱文泉. 基于多源数据产品集成分类制作的青藏高原现状植被图. 北京师范大学学报: 自然科学版, 2021, 57(6): 816-824.
[ZHANG H, ZHAO C L, ZHU W Q. A new vegetation map for Qinghai-Tibet Plateau by integrated classification from multi-source data products. Journal of Beijing Normal University: Natural Science, 2021, 57(6): 816-824.]
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周继华, 郑元润, 宋长青, 等. 青藏高原近似复原植被图. 国家青藏高原数据中心, 2022, https://data.tpdc.ac.cn/en/data/3a49fac7-bf9d-4b69-a855-bd2380ebaa0b.
[ZHOU J H, ZHENG Y R, SONG C Q, et al. Approximate vegetation restoration map of Qinghai-Tibet Plateau. National Tibetan Plateau/Third Pole Environment Data Center, 2022, https://data.tpdc.ac.cn/en/data/3a49fac7-bf9d-4b69-a855-bd2380ebaa0b.]
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Mountain treelines are thought to be sensitive to climate change. However, how climate impacts mountain treelines is not yet fully understood as treelines may also be affected by other human activities. Here, we focus on "closed-loop" mountain treelines (CLMT) that completely encircle a mountain and are less likely to have been influenced by human land-use change. We detect a total length of ~916,425 km of CLMT across 243 mountain ranges globally and reveal a bimodal latitudinal distribution of treeline elevations with higher treeline elevations occurring at greater distances from the coast. Spatially, we find that temperature is the main climatic driver of treeline elevation in boreal and tropical regions, whereas precipitation drives CLMT position in temperate zones. Temporally, we show that 70% of CLMT have moved upward, with a mean shift rate of 1.2 m/year over the first decade of the 21st century. CLMT are shifting fastest in the tropics (mean of 3.1 m/year), but with greater variability. Our work provides a new mountain treeline database that isolates climate impacts from other anthropogenic pressures, and has important implications for biodiversity, natural resources, and ecosystem adaptation in a changing climate.© 2023 John Wiley & Sons Ltd.
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基金

青海省国土整治与生态修复中心政府采购项目 [青海诚鑫公招(服务)](2023-076)
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