Intensified risk to ecosystem productivity under climate change in the arid/humid transition zone in northern China

Assessing the climate change risk faced by the ecosystems in the arid/humid transition zone(AHTZ) in northern China holds scientific significance to climate change adaptation. We simulated the net primary productivity(NPP) for four representative concentration pathways(RCPs) using an improved Lund-Potsdam-Jena model. Then a method was established based on the NPP to identify the climate change risk level. From the midterm period(2041–2070) to the long-term period(2071–2099), the risks indicated by the negative anomaly and the downward trend of the NPP gradually extended and increased. The higher the scenario emissions, the more serious the risk. In particular, under the RCP8.5 scenario, during 2071–2099, the total risk area would be 81.85%, that of the high-risk area would reach 54.71%. In this high-risk area, the NPP anomaly would reach –96.00±46.95 gC·m~(-2)·a~(-1), and the rate of change of the NPP would reach –3.56±3.40 gC·m~(-2)·a~(-1). The eastern plain of the AHTZ and the eastern grasslands of Inner Mongolia are expected to become the main risk concentration areas. Our results indicated that the management of future climate change risks requires the consideration of the synergistic effects of warming and intensified drying on the ecosystem.     

基于模式优选的21世纪中国气候变化情景集合预估

未来气候变化情景预估是制定气候变化应对和适应策略的科学基础。本文利用参与耦合模式比较计划第五阶段（CMIP5）的30个气候模式的模拟数据,通过评估各模式对历史气候变化的模拟能力,筛选出模拟区域气候变化的最优模式组合,进而建立偏最小二乘回归（PLS）集合预估模型,据此利用最优模式模拟结果预估区域温度和降水变化情景。通过与历史数据的对比,研究发现本文基于最优模式建立的PLS集合预估模型不仅优于传统的多模式集合平均,而且也优于利用全部模式建立的PLS集合预估模型,体现了模式优选过程的重要性。本文基于优选模式的PLS集合预估模型预估结果表明：① 21世纪各区域温度将持续上升,且冬半年升温速率总体大于夏半年,北方地区升温速率总体高于南方地区;RCP 4.5排放情景下温度上升先快后慢,转折点出现在21世纪中期,RCP 8.5排放情景下,呈持续增加趋势,至21世纪末的升温幅度约为RCP 4.5情景的2倍。② 21世纪各区降水变化均呈显著增加趋势,并表现出高排放情景大于低排放情景,少雨区大于多雨区的特征,但是降水增加过程伴有明显的年代际波动。对比发现,传统的等权重集合平均全部模式（EMC）方法预估的中国夏季变暖速率高于冬季,且降水基本呈线性增加,有悖于全球变暖的基本特征及中国降水具有鲜明的年代际变化特征的基本认识。因而,本文预估的温度和降水变化特征均更符合中国气候变化的基本规律。     

基于CMIP5模式的黑河流域潜在蒸散量预估

蒸散发是干旱内陆河流域水资源的主要耗散途径。预估黑河流域未来潜在蒸散量（ET₀）可为气候变化条件下流域水资源的优化管理提供基础数据支撑。使用1960—2014年黑河流域气象数据,采用FAO-56Penman-Monteith公式计算流域潜在蒸散量;基于同期NCEP（美国环境预报中心）再分析资料及2006—2100年CMIP5中CNRM-CM5模式的RCP4.5、RCP8.5路径预测数据,经统计降尺度模拟与偏差校正,预估了流域未来潜在蒸散量;通过旋转经验正交函数将流域各划分为3个子区,进行子区及全流域Mann-Kendall未来趋势分析。结果显示：（1）NCEP再分析资料与流域潜在蒸散量建立的逐步回归降尺度模型模拟效果好,经CNRM-CM5模式模拟及偏差校正,适宜于预估黑河流域未来潜在蒸散量。（2）预估RCP4.5路径流域2021—2050年、2071—2100年年均潜在蒸散量较1971—2000年分别增加3.49%、6.11%,RCP8.5路径分别增加4.64%、10.07%,RCP8.5路径增幅高于RCP4.5路径。（3）利用旋转经验正交函数可将两种路径流域未来蒸散量划分为3个子区,RCP4.5、RCP8.5路径黑河流域Ⅰ区潜在蒸散量各为不显著、显著的下降趋势,两种路径下Ⅱ区、Ⅲ区及全流域均为显著上升趋势。     

全球变化下中国南海诸岛珊瑚礁热压力临时避难所研究

选取第五次耦合模式比较计划（CMIP5）模式中较适宜于南海海表面温度（SST）模拟的加拿大地球系统模式(CanESM2),并获取其在IPCC RCP2.6、RCP4.5和RCP8.5温室气体排放情景下模拟的2006-2100年南海SST数据。基于南海诸岛珊瑚礁和线性回归方法分析了RCPs情景下的珊瑚礁区夏季SST上升趋势,并基于热周指数(DHW, Degree Heating Weeks)及年白化时间指数分析了RCPs情景下的南海诸岛珊瑚礁热压力临时避难所,主要得出以下结论：① RCPs情景下,明显变暖的珊瑚礁海域均为南沙群岛;② 年白化时间不晚于全球珊瑚礁平均年白化时间的珊瑚礁像元占南海诸岛总珊瑚礁像元的比例,在RCP2.6、RCP4.5和RCP8.5情景下分别为17%、29%和42%,均分布在南沙群岛;③ RCPs情景下,较高纬度的西沙群岛、中沙群岛和南沙群岛北部为未来南海诸岛珊瑚礁热压力临时避难所。     

气候变化背景下青冈分布变化及其对中国亚热带北界的指示意义

气候是影响植被类型和分布的关键因素,植被类型和分布格局也能反映气候的地域差异。随着气候变暖,全球气温和降水格局都将发生变化,植被类型和分布格局也将随之改变。而植物对气候变化的响应存在一定的滞后性,因此仅用气候指标研究亚热带北界及其移动具有一定的局限性。以青冈（Cyclobalanopsis glauca (Thunberg) Oersted）为研究对象,应用最大熵模型（Maxent）,研究了其对气候变化的响应并探讨了气候变化情景下青冈分布格局变化对中国亚热带北界移动的指示意义。结果表明：影响青冈分布的主导环境因子为年降水量、最冷季降水量、气温年变化范围和最冷月最低气温;随着气候变暖,青冈分布北界将向北移动,其分布质心亦向西北移动,预示着在气候变暖的背景下,到21世纪中叶中国亚热带北界将向北移动约1个纬度。     

综合湿度和温度影响的中国未来热浪预估

地面空气湿度直接影响人体驱散热负荷的效率,持续高温高湿天气将会严重影响人体健康。基于综合考虑温度和湿度协同作用的热胁迫指数——湿球黑球温度(WBGT)指数定义热浪,利用参考时期(1986—2005年)中国824个气象站点逐日平均气温和逐日相对湿度资料以及CMIP5多模式相应模拟数据,论文定量描述了未来时期(2076—2095年)不同排放情景下(RCP2.6、RCP4.5和RCP8.5)中国大陆地区可能遭遇的热浪事件的空间分布特征及其变化。研究结果表明：① 最有效的减排情景(RCP2.6)和高排放情景(RCP8.5)下中国大陆地区的平均热浪日数分别是参考时期的3.4倍和6.6倍,平均热浪强度(一年内所有热浪事件中日平均WBGT指数的最大值)也相对升高了1.6 ℃和4.9 ℃,未来时期RCP8.5情景下中国东部和南部地区的最高年均热浪强度甚至将达到40 ℃;② 虽然青藏高原地区的热浪强度等级低,但是未来时期热浪日数的增加幅度较为显著;③ 华南、长江中下游以及少数西南地区是综合考虑气温和湿度协同作用对人体热舒适的影响下,未来时期可能发生热浪最严重的地区,如果不考虑湿度要素的影响,那么将极有可能低估热浪在中国华南和东部等湿度较高地区的强度和影响。     

中国生态过渡带分布的空间识别及情景模拟

在全球变化及其生态环境效应研究中,如何对生态过渡带的空间分布格局及变化情景进行空间定量识别和模拟分析,对揭示气候变化和人类活动对全球变化的响应及反馈具有指示性意义。在对HLZ模型进行修正和拓展的基础上,建立了生态过渡带类型的空间识别方法。并基于1981—2010年的全国782个气候观测站点数据,在实现全国生态过渡带类型及分布的空间识别基础上,结合3种气候情景数据CMIP5 RCP 2.6、RCP 4.5和RCP 8.5,实现了T0（1981—2010年）、T1（2011—2040年）、T2（2041—2070年）和T3（2071—2100年）4个时段内全国生态过渡带的空间分布格局及其未来情景模拟。另外,引入平均中心空间分析模型,对全国生态过渡带平均中心的时空偏移趋势进行了定量分析。结果显示：在T0~T3时段内,全国共出现41种生态过渡带类型,约占全国陆地面积的18%;冷温带草原/湿润森林与暖温带干旱森林过渡带（564238.5 km²）、冷温带湿润森林与暖温带干旱/湿润森林过渡带（566549.75 m²）、北方湿润/潮湿森林与冷温带湿润森林过渡带（525750.25 km²）是最主要的3种生态过渡带类型。面积占到全国生态过渡带总面积的35%;2010—2100年期间的冷温带荒漠灌丛与暖温带荒漠灌丛/有刺草原过渡带的增加速度最快,在3种情景RCP 2.6、RCP 4.5和RCP 8.5下,其面积将分别增加3604.2 km²/10a、10063.1 km²/10a和17242 km²/10a;寒冷型生态过渡带类型总体上呈向暖湿型过渡带类型增加的趋势;北方潮湿森林与冷温带湿润/潮湿森林过渡带的平均中心偏移幅度最大,在4个时段内整体向东北方向偏移,其偏移幅度将超过150 km。另外,随着气温的逐渐上升和降水量的增加,中国北方的生态过渡带整体呈向北偏移趋势,南方生态过渡带则逐渐减少且平均中心呈现逐渐向高海拔地区退缩的趋势,气候变化对青藏高原区生态过渡带时空格局的影响日益显著。     

Spatial identification and scenario simulation of the ecological transition zones under the climate change in China

Explicitly identifying the spatial distribution of ecological transition zones(ETZs) and simulating their response to climate scenarios is of significance in understanding the response and feedback of ecosystems to global climate change. In this study, a quantitative spatial identification method was developed to assess ETZ distribution in terms of the improved Holdridge life zone(iHLZ) model. Based on climate observations collected from 782 weather stations in China in the T0(1981–2010) period, and the Intergovernmental Panel on Climate Change Coupled Model Intercomparison Project(IPCC CMIP5) RCP2.6, RCP4.5, and RCP8.5 climate scenario data in the T1(2011–2040), T2(2041–2070), and T3(2071–2100) periods, the spatial distribution of ETZs and their response to climate scenarios in China were simulated in the four periods of T0, T1, T2, and T3. Additionally, a spatial shift of mean center model was developed to quantitatively calculate the shift direction and distance of each ETZ type during the periods from T0 to T3. The simulated results revealed 41 ETZ types in China, accounting for 18% of the whole land area. Cold temperate grassland/humid forest and warm temperate arid forest(564,238.5 km~2), cold temperate humid forest and warm temperate arid/humid forest(566,549.75 km~2), and north humid/humid forest and cold temperate humid forest(525,750.25 km~2) were the main ETZ types, accounting for 35% of the total ETZ area in China. Between 2010 and 2100, the area of cold temperate desert shrub and warm temperate desert shrub/thorn steppe ETZs were projected to increase at a rate of 4% per decade, which represented an increase of 3604.2, 10063.1, and 17,242 km~2 per decade under the RCP2.6, RCP4.5, and RCP8.5 scenarios, respectively. The cold ETZ was projected to transform to the warm humid ETZ in the future. The average shift distance of the mean center in the north wet forest and cold temperate desert shrub/thorn grassland ETZs was generally larger than that of other ETZs, with the mean center moving to the northeast and the shift distance being more than 150 km during the periods from T0 to T3.In addition, with a gradual increase of temperature and precipitation, the ETZs in northern China displayed a shifting northward trend, while the area of ETZs in southern China decreased gradually, and their mean center moved to high-altitude areas. The effects of climate change on ETZs presented an increasing trend in China, especially in the Qinghai-Tibet Plateau.     

RCPs情景下未来青海高原气候变化趋势预估

利用 CMIP5(Coupled Model Intercomparison Project Phase 5)耦合模式结果对 RCPs(Representative Concentration Pathways)情景下的青海高原气温、降水变化趋势及极端气候事件2011-2100年演变特征进行了预估。结果表明:在21世纪,青海高原年平均气温显著升高,RCP2.6、RCP4.5 和 RCP8.5排放情景下增温速率分别为0.06 ℃/10a、0.24 ℃/10a和0.61 ℃/10a。年降水量将明显增加,幅度1.4～7.0 mm/10a。青海高原21世纪与气温、降水有关的事件都有趋于极端化的趋势,极端冷指标下降,极端暖指标均明显上升。极端降水频次增加,强度加重,且变化幅度与排放强度成正比。     

基于FLUS-InVEST模型的中国未来土地利用变化及其对碳储量影响的模拟

基于代表性浓度路径情景（Representative Concentration Pathways, RCPs），耦合FLUS-InVEST（Future Land Use Simulation-Integrated Valuation of Ecosystem Services and Trade-offs, FLUS-InVEST）模型，以土地利用视角模拟了中国2100年的陆地生态系统碳储量，探讨其空间分异。结果表明：1）历史土地利用变化作用下，中国生态系统碳储量减少中心由华北地区转向东北地区，增加中心由西北地区转向西南地区；碳储量的减少由林地生态系统转向草地生态系统。2）未来RCPs情景下，中国林地生态系统碳储量都将持续增加，草地生态系统碳储量持续减少。RCP 6.0情景下，中国林地面积将增加9.43%左右，草地面积减少5.42%，全国林地碳储量较2010年增加2 332.64 Tg，而草地碳储量将损失1 719.03 Tg。在RCP 8.5情景下，全国林地面积增加5.15%，草地面积将减少5.10%，林地碳储量较2010年将增加1 754.59 Tg，草地碳储量将损失2 468.80 Tg。3）RCP 6.0情景对未来碳汇贡献度较RCP 8.5情景大。在RCP 6.0情景下，植被地上碳储量和表层土壤碳储量分别净增加127.12和83.67 Tg。但在RCP 8.5情景下，植被地上碳储量和表层土壤碳储量分别净减少24.67和32.41 Tg。4）不同RCPs情景下，碳储量增长均集中在横断山-秦岭-太行山-大兴安岭和雪峰山-太行山-大兴安岭两带；减少区域主要分布于云贵高原、四川盆地和京津冀地区。     

东北地区未来气候变化对农业气候资源的影响

为探求未来气候变化对东北地区农业气候资源的影响,本文基于区域气候模式系统输出的东北地区IPCC AR5提出的低辐射和高辐射强迫RCP_4.5（低排放）、RCP_8.5（高排放）情景下2005-2099年气象资料,通过与东北地区1961-2010年91个气象站点观测资料同化,分析了历史资料（Baseline）、RCP_4.5、RCP_8.5情景下东北地区农业热量资源和降水资源空间分布及其变化趋势。结果表明：① 年均温度空间分布自南向北降低,未来各地区温度均有升高,RCP_8.5情景下升温更明显,Baseline情景年均温度为7.70 ℃,RCP_4.5和RCP_8.5年均温度分别为9.67 ℃、10.66 ℃;其他农业热量资源随温度变化一致,具体≥ 10 ℃初日提前3 d、4 d,初霜日推迟2 d、6 d,生长季日数延长4 d、10 d,积温增加400 ℃·d、700 ℃·d;水资源稍有增加,但不明显。② 历史增温速率为0.35 ℃/10a,未来增温速率最快为RCP_8.5情景0.48 ℃/10a,高于RCP_4.5的0.19 ℃/10a。21世纪后期,RCP_8.5增温趋势明显快于RCP_4.5,北部地区增温更加速。其他农业热量资源随温度变化趋势相一致,但具体空间分布有所不同。生长季降水总体呈增加趋势,但不显著,年际间变化较大;东部地区降水增加,西部减少。未来东北地区总体向暖湿方向发展,热量资源整体增加,但与降水的不匹配可能将会对农业生产造成不利的影响。     

Impacts of future climate change on agroclimatic resources in Northeast China

In this study, the spatial distribution and changing trends of agricultural heat and precipitation resources in Northeast China were analyzed to explore the impacts of future climate changes on agroclimatic resources in the region. This research is based on the output meteorological data from the regional climate model system for Northeast China from 2005 to 2099, under low and high radiative forcing scenarios RCP4.5 (low emission scenario) and RCP8.5 (high emission scenario) as proposed in IPCC AR5. Model outputs under the baseline scenario, and RCP4.5 and RCP8.5 scenarios were assimilated with observed data from 91 meteorological stations in Northeast China from 1961 to 2010 to perform the analyses. The results indicate that: (1) The spatial distribution of temperature decreases from south to north, and the temperature is projected to increase in all regions, especially under a high emission scenario. The average annual temperature under the baseline scenario is 7.70°C, and the average annual temperatures under RCP4.5 and RCP8.5 are 9.67°C and 10.66°C, respectively. Other agricultural heat resources change in accordance with temperature changes. Specifically, the first day with temperatures ≥10°C arrives 3 to 4 d earlier, the first frost date is delayed by 2 to 6 d, and the duration of the growing season is lengthened by 4 to 10 d, and the accumulated temperature increases by 400 to 700°C·d. Water resources exhibit slight but not significant increases. (2) While the historical temperature increase rate is 0.35°C/10a, the rate of future temperature increase is the highest under the RCP8.5 scenario at 0.48°C/10a, compared to 0.19°C/10a under the RCP4.5 scenario. In the later part of this century, the trend of temperature increase is significantly faster under the RCP8.5 scenario than under the RCP4.5 scenario, with faster increases in the northern region. Other agricultural heat resources exhibit similar trends as temperature, but with different specific spatial distributions. Precipitation in the growing season generally shows an increasing but insignificant trend in the future, with relatively large yearly fluctuations. Precipitation in the eastern region is projected to increase, while a decrease is expected in the western region. The future climate in Northeast China will change towards higher temperature and humidity. The heat resource will increase globally, however its disparity with the change in precipitation may negatively affect agricultural activities.     

基于CMIP5模式的干旱内陆河流域未来气候变化预估

我国西北干旱半干旱地区水资源短缺、生态环境脆弱,未来气候变化预估对水资源管理具有重要的现实意义。以黑河流域为研究区,基于1960-2014年月值NCEP再分析资料与气象要素实测资料,建立逐步回归降尺度模型;针对模型不足,提出一种补充逐步回归降尺度模型;经2006-2014年CMIP5中CNRM-CM5模式的区域适用性评价,选取适宜模型进行2016-2060年CNRM-CM5模式下的流域未来气候变化预估。主要结论为：（1）补充逐步回归模型的模拟效果总体要好于逐步回归模型,两模型对流域气温的模拟效果要好于降水。（2）降尺度模型的CNRMCM5模式适用性评价表明,RCP4.5与RCP8.5路径下,补充回归模型的适用性总体好于逐步回归模型。（3）两种路径下,黑河流域上中游未来年均降水量分别为324.94 mm、330.15 mm,未来流域降水分布的不均匀性增强。（4）两种路径下黑河流域中下游未来年均气温分别为10.25℃、10.77℃。     

青藏高原维管植物物种丰富度分布的情景模拟（英文）

For quantitatively explaining the correlations between the vascular plant species abundance(VPSA) and habitat factors, a spatial simulation method has been developed to simulate the distribution of VPSA on the Qinghai-Tibet Plateau. In this paper, the vascular plant type, land cover, mean annual biotemperature, average total annual precipitation, topographic relief, patch connectivity and ecological diversity index were selected to screen the best correlation equation between the VPSA and habitat factors on the basis of 37 national nature reserves on the Qinghai-Tibet Plateau. The research results show that the coefficient of determination between VPSA and habitat factors is 0.94, and the mean error is 2.21 types per km~2. The distribution of VPSA gradually decreases from southeast to northwest, and reduces with increasing altitude except the desert area of Qaidam Basin. Furthermore, the scenarios of VPSA on the Qinghai-Tibet Plateau during the periods from 1981 to 2010(T0),from 2011 to 2040(T2), from 2041 to 2070(T3) and from 2071 to 2100(T4) were simulated by combining the land cover change and the climatic scenarios of CMIP5 RCP2.6, RCP4.5 and RCP8.5. The simulated results show that the VPSA would generally decrease on the Qinghai-Tibet Plateau from T0 to T4. The VPSA has the largest change ratio under RCP8.5 scenario, and the smallest change ratio under RCP2.6 scenario. In general, the dynamic change of habitat factors would directly affect the spatial distribution of VPSA on the Qinghai-Tibet Plateau in the future.     

中国北方干湿过渡区生态系统生产力的气候变化风险评估

气候变化风险是人类社会发展面临的严峻挑战,评估识别对气候波动响应敏感且复杂的干湿过渡区生态系统所面临的气候变化风险是一个重要科学问题,对区域气候治理和风险管理具有科学意义。本文利用参与耦合模式比较计划第五阶段（CMIP5）的多气候模式多情景数据,通过改进和验证Lund-Potsdam-Jena（LPJ）动态全球植被模型,辨识未来不同时段生态系统生产力的气候变化风险等级及其时空分布,明晰气候因子对净初级生产力（NPP）风险的作用特征。结果表明：未来中远期干湿过渡区生态系统生产力面临的气候变化风险面积将可能扩大,风险等级将可能提升,高排放情景下的风险更加严重,主要表现为NPP距平为负,且仍有继续下降的趋势。尤其是典型浓度路径（RCP8.5）情景下,81.85%的地区将可能面临气候变化风险,54.71%将达到高风险。2071—2099年,RCP8.5高风险区的NPP距平将达到(-96.00±46.95) gC m^-2 a^-1,NPP变化速率将达到(-3.56±3.40) gC m^-2 a^-1。干湿过渡区东部平原和内蒙古东部草原区预估将可能成为风险主要集中区域,这些地区未来的植被生长将可能受到气候变化的不利影响,增温加剧和干旱程度加重可能是未来气候变化风险的重要驱动因素。     

气候变化对淮河流域水资源及极端洪水事件的影响

利用法国国家气象研究中心气候模型（Centre National de Recherches Météorologiques Climate Model, CNRM）典型代表性浓度路径（Representative Concentration Pathway, RCP）情景资料和可变下渗容量模型（Variable Infiltration Capacity Model,VIC）,分析了淮河流域未来气温、降水、水资源及可能洪水的变化趋势。结果表明,淮河流域未来气温将持续升高,RCP2.6、RCP4.5和RCP8.5情景下未来2021~2050年较基准期（1961~1990年）升幅分别约为1.13℃、1.10℃和1.35℃;流域降水可能呈现略微增加趋势,3种排放情景下2021~2050年降水较基准期将分别增加5.81%、8.26%和6.94%;VIC模型在淮河流域具有较好的适用性,能较好地模拟淮河流域的水文过程,在率定期和检验期,模型对王家坝站和蚌埠站模拟的水量相对误差都在5%以内,日径流过程的Nash-Sutcliffe模型效率系数（NSE）在0.70以上,月径流过程的NSE达到0.85以上。气候变化将导致淮河流域水文循环强度增加,流域水资源总体将可能呈增加趋势,王家坝站和蚌埠站断面洪水事件的发生可能性将增大。     

青藏高原维管植物物种丰富度分布的情景模拟

如何充分利用离散的观测数据,通过对维管植物物种分布丰富度及其与生境因子之间的相互作用和影响机理的定量分析,实现维管植物物种丰富度的空间分布及其情景模拟,是目前生物多样性研究前沿和核心内容之一。针对这一问题,在实现青藏高原37个国家自然保护区的维管植物物种数量收集和边界数据矢量化的基础上,分别进行维管植物物种数量与土地覆盖类型、环境因子和景观生态指数等三大类生境因子之间的相关关系的定量计算和对比分析,筛选和确定最佳相关分析方程,进而构建青藏高原维管植物物种丰富度的空间模拟分析模型。该模型中,维管植物物种丰富度与生境因子之间的复相关系数为0.94,模型验证结果表明,青藏高原的维管植物物种的平均丰富度为496.79种/100 km²,其空间分布格局整体上呈东南向西北逐渐减少趋势;另外,除柴达木盆地荒漠区域以外,维管植物物种的空间分布随海拔的升高而减少。基于CMIP5 RCP 2.6、RCP 4.5和RCP 8.5三种气候情景模拟获得的青藏高原维管植物物种丰富度未来情景结果显示,在T0-T4（2010-2100）时段内,青藏高原维管植物物种丰富度整体将呈减少趋势。RCP 8.5情景下青藏高原维管植物物种丰富度的变化幅度最大,而RCP 2.6情景下的维管植物物种丰富度的变化幅度最小。研究表明,本文构建的模型能够对青藏高原维管植物物种丰富度的空间分布格局及其未来情景进行模拟分析,模拟结果可为青藏高原生物多样性及其对气候变化响应的综合评估和情景模拟提供方法和技术支持。     

黄河源区多年冻土空间分布变化特征数值模拟

基于IPCC第五次评估报告预估的气温变化情景,采用数值模拟的方法对黄河源区典型冻土类型开展模拟,推算过去及预测未来黄河源区冻土分布空间变化过程和发展趋势。结果表明：1972-2012年源区多年冻土只有少部分发生退化,退化的冻土面积为833 km²,季节冻土主要集中在源区东南部的热曲谷地、小野马岭以及两湖流域南部的汤岔玛地带;RCP 2.6、RCP 6.0、RCP 8.5情景下,2050年多年冻土退化为季节冻土的面积差别不大,分别为2224 km²、2347 km²、2559 km²,占源区面积的7.5%、7.9%、8.6%;勒那曲、多曲、白马曲零星出现季节冻土,野牛沟、野马滩以及鄂陵湖东部的玛多四湖所在黄河低谷大片为季节冻土;2100年多年冻土退化为季节冻土的面积分别为5636 km²、9769 km²、15548 km²,占源区面积的19%、32.9%、52.3%;星宿海、尕玛勒滩、多格茸的多年冻土发生退化,低温冻土变为高温冻土,各类年平均地温出现了不同程度的升高。到2100年,RCP 2.6情景下源区多年冻土全部退化为季节冻土主要发生在目前年平均地温高于-0.15 oC的区域,而-0.15~-0.44 oC的区域部分发生退化;RCP 6.0、RCP 8.5情景下目前年平均地温分别为高于-0.21 oC以及-0.38o C的区域多年冻土全部发生退化,而-0.21~-0.69 oC以及-0.38~-0.88 oC的区域部分发生退化。     

Evaluation of the carbon sequestration of Zhalong Wetland under climate change

Wetland ecosystems are crucial to the global carbon cycle.In this study,the Zhalong Wetland was investigated.Based on remote sensing and meteorological observation data from 1975–2018 and the downscaled fifth phase of the coupled model intercomparison project (CMIP5) climate projection dataset from 1961–2100,the parameters of a net primary productivity (NPP) climatic potential productivity model were adjusted,and the simulation ability of the CMIP5 coupled models was evaluated.On this basis,we analysed the spatial and temporal variations of land cover types and landscape transformation processes in the Zhalong Nature Reserve over the past 44 years.We also evaluated the influence of climate change on the NPP of the vegetation,microbial heterotrophic respiration (Rh),and net ecosystem productivity (NEP) of the Zhalong Wetland and predicted the carbon sequestration potential of the Zhalong Wetland from 2019–2029 under the representative concentration pathways (RCP) 4.5 and RCP 8.5 scenarios.Our results indicate the following:(1) Herbaceous bog was the primary land cover type of the Zhalong Nature Reserve,occupying an average area of 1168.02±224.05 km~2,equivalent to 51.84%of the total reserve area.(2)Since 1975,the Zhalong Nature Reserve has undergone a dry–wet–dry transformation process.Excluding several wet periods during the mid-1980s to early 1990s,the reserve has remained a dry habitat,with particularly severe conditions from 2000 onwards.(3) The 1975–2018 mean NPP,Rh,and NEP values of the Zhalong Wetland were 500.21±52.76,337.59±10.80,and 162.62±45.56 g C·m~(-2)·a~(-1),respectively,and an evaluation of the carbon balance indicated that the reserve served as a carbon sink.(4) From 1975–2018,NPP showed a significant linear increase,Rh showed a highly significant linear increase,while the increase in the carbon absorption rate was smaller than the increase in the carbon release rate.(5) Variations in NPP and NEP were precipitation-driven,with the correlations of NPP and NEP with annual precipitation and summer precipitation being highly significantly positive(P0.001);variations in Rh were temperature-driven,with the correlations of Rh with the average annual,summer,and autumn temperatures being highly significantly positive (P0.001).The interaction of precipitation and temperature enhances the impact on NPP,Rh and NEP.(6) Under the RCP 4.5 and RCP 8.5 scenarios,the predicted carbon sequestration by the Zhalong Wetland from 2019–2029 was 2.421 (±0.225)×10~(11) g C·a~(-1) and 2.407 (±0.382)×10~(11) g C·a~(-1),respectively,which were both lower than the mean carbon sequestration during the last 44 years (2.467 (±0.950)×10~(11) g C·a~(-1)).Future climate change may negatively contribute to the carbon sequestration potential of the Zhalong Wetland.The results of the present study are significant for enhancing the abilities of integrated eco-meteorological monitoring,evaluation,and early warning systems for wetlands.     

全球气候变化下南海诸岛保护优先区识别分析

全球变化下,珊瑚礁保护区是保护生物多样性、增强珊瑚礁对气候变暖抵抗力的有效方式,而维持珊瑚礁弹性是其核心内容。针对珊瑚礁最具有威胁性的热压力因子,基于南海1982—2009年卫星观测海表面温度（SST）数据和CMIP5加拿大地球系统模式CanESM2模型预估的2006—2100年南海SST数据构建热压力强度模型,从维持珊瑚礁弹性的角度识别IPCC RCP 4.5和RCP 8.5情景下南海诸岛保护优先区。结果表明：RCP 4.5和RCP 8.5情景下13%左右的南海诸岛珊瑚礁识别为保护优先区。根据热压力强度与珊瑚抵抗力及避难所关系,西沙群岛七连屿和晋卿岛近年观测与未来预估的热压力强度均比较低,在保障其服务功能的基础上建议实施完全保护;东沙群岛东沙环礁和中沙环礁排洪滩近年观测急性热压力强度较高但未来预估热压力强度较低,建议实施50%禁止利用保护;中沙群岛黄岩岛近年观测和未来预估的急性热压力强度均比较低,建议实施50%多用途保护。南沙群岛有14%左右的珊瑚礁识别为保护优先区,根据其热压力强度可实施30%~100%禁止利用保护或30%~50%多用途保护。RCP 4.5和RCP 8.5情景下的南海诸岛保护优先区及保护对策,可为维持珊瑚礁生态弹性及应对全球气候变化提供重要的参考价值。