气候异常对森林火灾发生的影响研究

从近年频发的自然灾害(森林火灾、超强台风、高温干旱)入手,从气象与森林火灾的角度,对近百年来中国的气候变化,主要是气温、降水及极端气候事件的变化,对森林火灾发生发展的影响进行了分析,结果表明:气温升高,可能使火险期提前和延长;气温日较差大,可能使森林火险长期维持在一个较高水平,增加了引燃的可能性和扑救的难度;降水的年代际和区域间差异加大,使干旱年份和干旱地区发生森林火灾的可能性增大;极端气候事件的频发,加大了那些极端高温干旱地区火灾频发及发生重特大森林火灾的可能性。由于气象专家预估未来的20～100年,气温将持续上升,且极端气候事件出现的频率也将增加,因此未来的森林火险发展趋势不容乐观。     

气候变化与中国北方森林恢复和经营

全球气候变暖已经成为一个不争的事实。在全球气候变化背景下,我国的气温不断增高,降水和极端天气气候事件不断增多。根据气候变化现状和趋势,文章从陆地生态系统的可能响应、北方森林的分布变化、生产力、生物地球化学循环、火干扰等方面分析了气候变化对中国北方森林生态系统的可能影响,并提出了我国北方森林应对气候变化的适应性对策。     

北方针叶林有助于地球“退烧”

全球气候变暖导致各地气候出现了许多异常现象,这已引起了全世界的广泛关注。政府间气候变化专门委员会(IPCC)基于对大量数据的深入、全面的分析,得出了可信度很高的结论:气候在人类活动影响下,总体上呈增暖趋势。近50年来,全球平均气温的升高,有90%-95%的可能性是人为的。地球气候变暖,气温升高将导致更为频繁的洪水、热浪灾害,致使两极冰盖部分融化,海平面上升,部分太平洋岛国将被上升的海水淹没。气候变暖是21世纪全球面临的最严重挑战,自然已经向人类敲响了警钟。     

发展碳汇林业 应对气候变化

2010年,我国极端天气频发,使我们切身感受到气候变化的伤害。据了解,在过去一个世纪,全球气温已经上升了0.7℃,并且预计在21世纪后90年将持续升高1.8-2.4℃,气候变暖作为全球性议     

天然华北落叶松径向生长对气候变化的响应

在气候暖干化趋势下,进行森林经营树种对气候变化的响应研究,有助于适宜的经营技术构建以及森林经营对气候变化的应对。选取围场县龙头山林场天然华北落叶松,建立年轮宽度年表,应用相关分析、Mann-Kendall检验、逐步回归等方法,研究华北落叶松径向生长对气候变化的响应。结果表明:1)近60年来,本地区气温显著升高,在1980年发生升高突变;降水量有减少趋势,但变化趋势不明显。2)华北落叶松径向生长受气温与降水的双重影响,与多数气温因子呈显著负相关,与多数降水因子呈显著正相关,当年3,4月份降水是树木径向生长的重要限制因素。3)生长季极端高温与径向生长呈显著负相关,湿润指数与径向生长呈极显著正相关。4)利用当年生长季平均温度及3,4月份降水量和湿润指数模拟华北落叶松径向生长,发现在暖干化趋势下,研究区华北落叶松的生长将呈现减缓趋势。     

50余年来呼和浩特地区气候变化与厄尔尼诺-拉尼娜事件关系初探

选取了1961-2014年呼和浩特地区气候资料,结合同一时期发生的El Nino/La Nina事件,对气温、降水量和干旱特征与El Nino/La Nina事件的关系进行了统计分析,初步探讨了El Nino/La Nina事件对呼和浩特地区气候的影响。分析结果表明:1961年以来呼和浩特地区气温具有明显的波动升高的趋势;降水量年代际变化较为明显,20世纪60、70年代,降水为正距平;20世纪80、90年代,以及21世纪前10年,降水均为负距平,2011年以后降水开始逐渐增多。El Nino/La Nina事件对呼和浩特地区气候变化和干旱灾害具有一定的影响,El Nino年气温偏高,La Nina年气温偏低;El Nino和La Nina事件对呼和浩特地区降水都有减少的作用,El Nino事件中,降水量减少的概率和幅度更大。El Nino事件提高了呼和浩特地区发生干旱的概率;La Nina事件促使发生干旱的概率较小,但其促使发生干旱的程度可能更深一些。     

西双版纳近45年来气候变化及对热带作物的影响

根据云南省西双版纳州景洪市气象站1961年1月～2005年1月的气温及降水资料,分析了西双版纳近45年来的气候变化特征:降水量呈下降趋势(-20.72mm/10年),夏季降水量(-24.28mm/10年)减少较明显,春季降水量(11.18mm/10年)呈上升趋势;年平均气温呈上升趋势(0.262℃/10年),尤以冬季变暖最明显(0.483℃/10年);年极端低温的上升趋势(0.545℃/10年)远大于年极端高温的下降趋势(-0.088℃/10年)。大致可以以70年代末为界将近45年的西双版纳气候分为之前冷期、之后为暖期。同时讨论了气候变化对热带作物的影响和相应的适用技术及对策。     

碳汇，自然之源

全球气候变化的最明显表现就是气候变暖。全球温度在过去300年上升超过了0.7℃,因此气候变化已经发生。20世纪上升了0.5℃。最严重的变暖发生在1910～1940年间和1976年至今。最近1000年内,上世纪90年代是最温暖的,5个最温暖的年度有4个发生在90年代。1998年是1861年有记录以来全球最温暖的一年。1995年     

气候变化及其对纳帕海湿地的影响

通过收集纳帕海区域周边4个气象站1958-2008年温度、降水和结冰日数的气象观测资料,采用线性趋势估计以及Mann-Kendall检验法,对纳帕海区域50年气候进行分析,阐述气候变化对纳帕海湿地面积的影响。结果表明:纳帕海区域从1958年至今气温一直呈上升趋势,年平均气温升高1.2℃,气温线性变率为0.036℃/a;气温在1985年发生突变,由相对平稳的状态转为明显上升的状态。结冰日数和气温变化相反,显示下降的趋势,且突变在气温突变4年后发生。纳帕海区域近50年降水趋势变化不显著,但年际变率较大。纳帕海湿地近50年的变化受自然因素和人为因素叠加作用的影响,第1阶段(1955-1974年)主要受气候因素影响,湿地水域面积较大;第2阶段(1975-1997年)主要受气候因素和人为因素双重影响,湿地水域面积大幅减少;第3阶段(1998-2012年)受人类保护加强的影响,湿地水域面积扩大,但纳帕海湿地的内部生境处于退化中。     

发展碳汇林业 应对气候变化

2010年，我国极端天气频发，使我们切身感受到气候变化的伤害。据了解，在过去一个世纪，全球气温已经上升了0.7℃，并且预计在21世纪后90年将持续升高18—2．4℃，气候变暖作为全球性议题，已经引起各国政府和公众的广泛关注。2月22日，中共中央政治局就关于实现2020年我国控制温室气体排放行动目标问题进行第十九次集体学习。     

61年来滇西南地区干热河谷与热带雨林地区气候变化分析

根据元江和勐腊两地区1957—2018年的气候数据资料,采用线性趋势估计、累积距平法、Mann-Kendall突变检验法和小波分析法等方法,分析这两个区域气候和干、湿季变化趋势,探讨元江和勐腊地区气候因子的突变情况及变化周期。结果表明:(1)1957—2018年以来,干热河谷元江地区和热带雨林勐腊地区气温变化与西南地区气温变化存在显著差异;(2)两地区年均温、日照、降水量均呈显著上升趋势,相对湿度相对下降,两区域间气候变化与全球变暖趋势相对一致。干热河谷地区干湿季变化中气温变化趋势强于雨林地区,降水变化趋势低于雨林地区;(3)两地区气温突变时间为2007、1985年,降水出现多次变化的趋势。元江地区气温和降水变化主周期相同,为28 a周期变化,存在同步性,勐腊地区气温和降水变化主周期存在差异,分别为28 a和6 a。     

Analysis of potential impacts of climate change on forests of the United States Pacific Northwest

As global climate changes over the next century, forest productivity is expected to change as well. Using PRISM climate and productivity data measured on a grid of 3356 plots, we developed a simultaneous autoregressive (SAR) model to estimate the impacts of climate change on potential productivity of Pacific Northwest (PNW) forests of the United States. Productivity, measured by projected potential mean annual increment (PMAI) at culmination, is explained by the interaction of annual temperature, precipitation, and precipitation in excess of evapotranspiration through the growing season. By utilizing information regarding spatial error in the SAR model, the resulting spatial bias is reduced thereby improving the accuracy of the resulting maps. The model, coupled with climate change output from four generalized circulation models, was used to predict the productivity impacts of four different scenarios derived from the fourth IPCC special report on emissions, representing different future economic and environmental states of the world, viz., scenario A1B, A2, B1 (low growth, high economic development and low energy usage), and COMMIT. In these scenarios, regional average temperature is expected to increase from 0.5 to 4.5 °C, while precipitation shows no clear trend over time. For the west and east side of the Cascade Mountains, respectively, PMAI increases: 7% and 20% under A1B scenario; 8% and 23% under scenario A2; 5% and 15% under scenario B1, and 2% and 5% under the COMMIT scenario. These projections should be viewed as potential changes in productivity, since they do not reflect the mitigating effects of any shifts in management or public policy. For managers and policy makers, the results suggest the relative magnitude of effects and the potential variability of impacts across a range of climate scenarios.     

Assessing the impacts of climate change and nitrogen deposition on Norway spruce (Picea abies L. Karst) growth in Austria with BIOME-BGC

The aim of this paper is to determine whether a detectable impact of climate change is apparent in Austrian forests. In regions of complex terrain such as most of Austria, climatic trends over the past 50 years show marked geographic variability. As climate is one of the key drivers of forest growth, a comparison of growth characteristics between regions with different trends in temperature and precipitation can give insights into the impact of climatic change on forests. This study uses data from several hundred climate recording stations, interpolated to measurement sites of the Austrian National Forest Inventory (NFI). Austria as a whole shows a warming trend over the past 50 years and little overall change in precipitation. The warming trends, however, vary considerably across certain regions and regional precipitation trends vary widely in both directions, which cancel out on the national scale These differences allow the delineation of 'climatic change zones' with internally consistent climatic trends that differ from other zones. This study applies the species-specific adaptation of the biogeochemical model BIOME-BGC to Norway spruce (Picea abies (L.) Karst) across a range of Austrian climatic change zones, using input data from a number of national databases. The relative influence of extant climate change on forest growth is quantified, and compared with the far greater impact of non-climatic factors. At the national scale, climate change is found to have negligible effect on Norway spruce productivity, due in part to opposing effects at the regional level. The magnitudes of the modeled non-climatic influences on aboveground woody biomass increment increases are consistent with previously reported values of 20-40 kg of added stem carbon sequestration per kilogram of additional nitrogen deposition, while climate responses are of a magnitude difficult to detect in NFI data.     

Assessing rates of forest change and fragmentation in Alabama,USA, using the vegetation change tracker model

Forest change is of great concern for land use decision makers and conservation communities. Quantitative and spatial forest change information is critical for addressing many pressing issues, including global climate change, carbon budgets, and sustainability. In this study, our analysis focuses on the differences in geospatial patterns and their changes between federal forests and nonfederal forests in Alabama over the time period 1987–2005, by interpreting 163 Landsat Thematic Mapper (TM) scenes using a vegetation change tracker (VCT) model. Our analysis revealed that for the most part of 1990 s and between 2000 and 2005, Alabama lost about 2% of its forest on an annual basis due to disturbances, but much of the losses were balanced by forest regeneration from previous disturbances. The disturbance maps revealed that federal forests were reasonably well protected, with the fragmentation remaining relatively stable over time. In contrast, nonfederal forests, which are predominant in area share (about 95%), were heavily disturbed, clearly demonstrating decreasing levels of fragmentation during the time period 1987–1993 giving way to a subsequent accelerating fragmentation during the time period 1994–2005. Additionally, the identification of the statistical relationships between forest fragmentation status and forest loss rate and forest net change rate in relation to land ownership implied the distinct differences in forest cutting rate and cutting patterns between federal forests and nonfederal forests. The forest spatial change information derived from the model has provided valuable insights regarding regional forest management practices and disturbance regimes, which are closely associated with regional economics and environmental concerns.     

Forest growth response to changing climate between 1961 and 1990 in Austria

Using 30 years of climate records from 20 weather stations, we investigate the magnitude of temperature and precipitation change, and change in the length of the growing season between 1961 and 1990. Special attention is paid to the period between 1981 and 1990, because recent research suggests that, during this time span, forest productivity may have increased in the northern latitudes. In order to understand the importance of changes in climate on forest growth, we use the ecosystem model FOREST-BGC as a diagnostic tool to predict the annual net primary production (NPP). The results of our study indicate: no change in precipitation between 1961 and 1990; a significant (α = 0.05) increase in mean annual temperature of 0.72°C, mean annual minimum temperature (0.80°C), winter temperature (2.36°C) as well as an increase in the length of the temperature-controlled growing season by 11 days, resulting in a significant increase in diameter increment obtained from 1179 cores of Norway spruce across Austria. The trends in NPP are consistent with observed increment rates validating the use of biogeochemical modeling as a diagnostic tool to search for possible causes on changing environmental conditions.     

Assessing impact of climate change on forest cover type shifts in Western Himalayan Eco-region

Climate is a critical factor affecting forest ecosystems and their capacity to produce goods and services. Effects of climate change on forests depend on ecosystem-specific factors including dimensions of climate (temperature, precipitation, drought, wind etc.). Available information is not sufficient to support a quantitative assessment of the ecological, social and economic consequences. The present study assessed shifts in forest cover types of Western Himalayan Eco-region (700?4500 m). 100 randomly selected samples (75 for training and 25 for testing the model), genetic algorithm of rule set parameters and climatic envelopes were used to assess the distribution of five prominent forest cover types (Temperate evergreen, Tropical semi-evergreen, Temperate conifer, Subtropical conifer, and Tropical moist deciduous forests). Modelling was conducted for four different scenarios, current scenario, changed precipitation (8% increase), changed temperature (1.07°C increase), and both changed temperature and precipitation. On increasing precipitation a downward shift in the temperate evergreen and tropical semi-evergreen was observed, while sub-tropical conifer and tropical moist-deciduous forests showed a slight upward shift and temperate conifer showed no shift. On increasing temperature, an upward shift in all forest types was observed except sub-tropical conifer forests without significant changes. When both temperature and precipitation were changed, the actual distribution was maintained and slight upward shift was observed in all the forest types except sub-tropical conifer. It is important to understand the likely impacts of the projected climate change on the forest ecosystems, so that better management and conservation strategies can be adopted for the biodiversity and forest dependent community. Knowledge of impact mechanisms also enables identification and mitigation of some of the conditions that increase vulnerability to climate change in the forest sector.     

Regional impact assessment on forest structure and functions under climate change—the Brandenburg case study

A forest simulation model has been applied in a regional impact assessment to investigate impacts of climate change on forest structure and function in the Federal state of Brandenburg, Germany. The forest model FORSKA-M was linked to a GIS that included soil, groundwater table and land-use maps. Two climate scenarios (current climate and a climate change of 1.5 K temperature increase which is combined with a precipitation decrease of 10–20% on average) for 40 meteorological stations in and around Brandenburg were used to assess the sensitivity of species composition to climate change. Furthermore, the implications of vegetation changes for other forest functions were analysed by means of several indicators. To evaluate the impacts of climate change on biodiversity, measures of species diversity (Shannon’s and Simpson’s index) and habitat and structural diversity (Seibert’s index) were applied. The evaluation of impacts on groundwater recharge of natural and managed forests was carried out using the soil water balance model of FORSKA-M.At first, model simulations of the potential natural vegetation (PNV) on the whole area of Brandenburg with different climate scenarios were analysed. The results indicated that climatic warming would lead to a shift in the natural species composition in Brandenburg towards more drought tolerant species. The simulated diversity of the forests would be reduced, and groundwater recharge would be decreased.The majority of forests in the state of Brandenburg have been managed intensively in the past. At present, large areas of Brandenburg’s forests are dominated by pure stands of Scots pine, but current forest management practice aims at increasing the share of deciduous and mixed forests. In order to analyse the possible consequences of climate change on forest management, forest inventory data were used to initialise FORSKA-M with representative forest stands. Simulation experiments with three different management scenarios showed that the short to mid-term effects of climatic change in terms of species composition were not as severe as expected. However, the comparison of different diversity measures indicates a decrease in the species diversity in contrast to an increase in habitat diversity under climate warming. Furthermore, a decrease in productivity and groundwater recharge was simulated under the climate change scenario.The regional impact assessment corroborated the high sensitivity of natural forests in the region to the projected climatic change and it underlined the importance of adaptive management strategies to help forestry to cope with climatic change.     

Dynamics of forest composition and growth in Alabama of USA under human activities and climate fluctuation

Integrated analysis of forest dynamics under both anthropogenic influence and climatic change is crucial to indicating emergent patterns and meeting objectives of climate change mitigation. In this study, a long-term forest inventory data (1960s-2010s) in Alabama, USA were analyzed for patterns in relation to human activities and climate fluctuation. The results indicated that the species (or species groups) composition in Alabama’s forests was significantly different between all reported times, except for 2012–2015 based on Simpson’s index. Eastern hemlock trees declined dramatically. The overall forest communities became less homogeneous. Positive or negative correlation existed in the abundance of many species. The distribution of tree abundance along diameters for tree species followed exponential models. Both annual tree mortality and net growth rate increased from the 1960s. The total volume of growing stock increased from 14.4 million cubic feet in 1963 to 39.5 million cubic feet in 2016. The average volume of growing stock per acre also increased linearly with annual average air temperature, but not with annual precipitation. Based on the patterns of Alabama’s forests under climate fluctuation and human activities, some suggestions on developing strategies for the sustainability of Alabama forest were discussed.     

祁连山水源林生态系统结构与功能的研究

在祁连山水源涵养林区,围绕水源林生态系统结构与功能的动态变化,开展了森林小气候、森林水文生态效应的研究。结果表明,祁连山水源涵养林不仅具有拦蓄降水、缩小温差、保持较高土壤湿度等作用,而且具有十分显著的消洪补枯、涵养水源、保持水土的水文生态作用。森林覆被率６５％的流域比３２％的流域年枯水径流量增加２８８７ｍｍ,年洪水径流量减少９８８７ｍｍ;森林土壤贮水２９８１２～３９１９３ｍｍ,草地仅１８２０９ｍｍ;林地很少产生地表径流,草地年土壤流失量１７９３９ｋｇ·ｈｍ－２;高寒山区多年冻土与季冻土致使试验区河川径流系数高达０７３,蒸散较小为１５６５４ｍｍ;多年监测资料显示祁连山林分质量下降,冰川退缩,河川径流逐年减少,生态环境明显恶化,建议各级政府部门高度重视祁连山生态保护问题。     

Growth patterns and sensitivity to climate predict silver fir decline in the Spanish Pyrenees

Patterns in radial growth have often been used to predict forest decline since they are regarded as indicators of the tree responses to long-term stressors. However, the sensitivity of tree growth to climate, as a proxy of the trees’ adaptive capacity to short-term climatic stress, has received less attention. Here, we used retrospective tree-ring analyses to determine whether growth patterns and sensitivity to climate are related to Abies alba (silver fir) decline in the Spanish Pyrenees. We used regional climatic data to calculate normalised temperatures and drought indexes. Basal-area increment (BAI) was measured for declining (defoliation >50%) and non-declining (defoliation <50%) silver firs in four stands with contrasting decline levels. A dynamic factor analysis (DFA) was applied to test the hypothesis that declining and non-declining trees have experienced different long-term growth trends. Growth sensitivity to climate was computed as the average change in BAI per unit of change in a given climate variable. Declining trees showed a negative growth trend during the last 20?years. Trees with lower relative BAI and negative BAI trends showed stronger growth sensitivity to climate and higher defoliation than trees with the opposite characteristics. Our findings underscore the idea that long-term climatic warming seems to be a major driving factor of growth decline in Pyrenean silver fir forests. Ongoing growth reduction and enhanced growth sensitivity to climate may promote vegetation shifts in these declining forests located near the xeric edge of the species distribution area.