中国东部森林植被带划分之我见

简要回顾了中国东部森林植被带划分研究的历史及当前存在的争论。提出了中国东部植被带划分应以植被本身的特征，特别是地带性的生物群落集为主要依据，同时参照它们的区系组成和气候指标。根据上述原则将中国东部划分为６个植被带∶北方针叶林带、凉温带针阔混交林带、温带落叶阔叶林带、暖温带常绿落叶阔叶混交林带、亚热带常绿阔叶林带和热带雨林、季雨林带，并对各植被带的特征作了简要的描述。阐述了对一些植被带名称、界线改动的原因，特别讨论了我国常绿落叶阔叶混交林以及常绿阔叶林生物气候带的归属问题，认为前者归属于暖温带植被，后者归属于亚热带植被为宜。     

中国东部森林植被带划分之我见

简要回顾了中国东部森林植被带划分研究的历史及当前存在的争论。提出了中国东部植被带划分应以植被本身的特征,特别是地带性的生物群落集为主要依据,同时参照它们的区系组成和气候指标。根据上述原则将中国东部划分为6个植被带∶北方针叶林带、凉温带针阔混交林带、温带落叶阔叶林带、暖温带常绿落叶阔叶混交林带、亚热带常绿阔叶林带和热带雨林、季雨林带,并对各植被带的特征作了简要的描述。阐述了对一些植被带名称、界线改动的原因,特别讨论了我国常绿落叶阔叶混交林以及常绿阔叶林生物气候带的归属问题,认为前者归属于暖温带植被,后者归属于亚热带植被为宜。     

The effect of 50 years of landscape change on species richness and community composition

We analysed a 50-year dataset of avian species observations to determine how richness and community composition varied over a period of landscape-scale environmental change. Our study area, northern lower Michigan, has experienced substantial land-use and land-cover change over time. Like much of the northern Midwest, it has shifted from a largely unpopulated, post-logging shrubland to a moderately populated closed-canopy forest. Such changes are generally expected to influence overall richness and community composition. We found that regional richness per year remained virtually unchanged over the study period. Year-to-year variation in species number was surprisingly low. Richness totals included vastly different species groups as the composition of the regional bird community changed substantially over time. Changes in the types of species present appear to reflect deterministic changes in habitat. The number of grassland and open-habitat species decreased, for example, while species associated with older forests and urban habitats increased. Our results suggest that habitat changes at the landscape scale do not necessarily lead to changes in the number of species a region can support. Such changes, however, do appear to influence the types of species that will occupy a region, and can lead to substantial changes in community composition.     

1961-2010年中国东部林区降水的完整日值序列建立与变化特征

高精度地对各气象站缺测降水资料进行插补,从而获得完整序列的降水资料,对于提高气候变化影响分析的时空精度具有十分重要的意义.本文利用空间相关和逐步回归法,对东部林区月内有单日缺测或不多于7 d缺测的降水资料进行插补,最终建立了853个站自1961-2010年完整序列的降水资料.在此基础上,应用趋势分析法,分析了1961-2010年降水量、降水日数和极端降水事件的变化特性.结果表明： 1961-2010年,研究区年降水量略呈不显著增加趋势,倾向率为5.58 mm·(10 a)^-1,年代际变化明显;年降水日数呈显著减少趋势.极端降水日数和极端降水量呈显著上升趋势,倾向率分别为0.12 d·(10 a)^-1、10.22 mm·(10 a)^-1.尤其是20世纪90年代以后,该区极端降水事件明显偏多偏强,极端降水量对总降水量的比率也呈显著增加趋势.极端降水日数和极端降水量均在1993年发生突变.     

The impact investigation and adaptation strategy analysis of climate change on nature reserve in China

Nature reserve has been served as the important pathway for biodiversity conservation and carbon storage. Global climate change is an indisputable fact and impacted the biodiversity and nature reserve. How nature reserves adapt to climate change has drawn more and more concerns. This research conducted questionnaires of 68 national nature reserves from 24 provincial regions, and the questionnaires showed that all surveyed nature reserves experienced climate change, and 68.57%, 61.43% and 68.57% of nature reserves, respectively, considered warming temperature, precipitation change, and occurrence of extreme climate events as new threats to them. These new factors directly threat the distribution range and survival of endangered species, change of ecosystem function, enhance of pest and disease damages, and directed damage the infrastructures. However, most of the surveyed nature reserves did not consider the systematic monitoring the facts of climate change, and lack actions and strategies of initiative adaptation to climate change. At last, we proposed the strategies for nature reserves to adapt to climate change, including enhancing the monitoring on the impact of climate change, making scientific planning and designing for development of nature reserves, decreasing the pressure through sustainable development, and enhancing the scientific research and the investment to improve the ability of nature reserves to adapt to climate change.     

东北地区近50年来极端降水和干燥事件时空演变特征

利用东北地区93个国家常规气象观测站1951~2002年逐日降水资料,分析了东北地区的暴雨、严重干燥事件等极端降水事件的时空演变特征,从极端降水事件发生频率和强度变化的角度解释旱涝灾害加剧的原因。结果表明,近52年来,小雨事件发生频次显著减少;暴雨发生频次变化不大,但强度增强;严重干燥事件显著增加;严重湿润事件显著下降。因此,在东北地区降水总量具有减少趋势的背景下,降水事件还有向极端化发展的倾向,降水分布变得更不均匀,从而可能引起更多、更强的旱涝灾害,尤其是旱灾,从而对东北地区的生态环境,尤其是农业生产带来不利的影响,这应引起重视。     

中国西北干旱区降水时空分布特征

利用中国西北干旱区122个气象站点1961—2011年月降水量资料,运用线性趋势、Mann-Kendall非参数趋势和突变检验法、Morlet小波分析等方法研究了西北干旱区降水量空间分布及多时间尺度下的变化规律和趋势。结果表明:近50年来西北干旱区降水量呈增加趋势,95.9%的站点有增湿特征,全区增湿趋势为9.31mm/10a(P0.01),但增湿幅度存在区域差异性,其中祁连山亚区(38.67mm/10a)增湿最明显;从季节来看,冬季增湿具有全区普遍性,但夏季增湿的区域差异性特征明显。全区及各亚区降水量在20世纪80年代至90年代初有明显的突变特征,除内蒙西部亚区外均通过了0.01的显著性水平检验,降水量序列存在4、8、12a和22a振荡周期,其中22a尺度振荡周期最强,其次是12a尺度。全区32%的年份降水量属正常范围,偏干年份为24%,异常偏干年份为12%,异常偏湿和偏湿年份均为16%。20世纪70年代之前降水量略低于标准降水均值,80年代开始有区域性增湿趋势,90年代之后全区增湿均较明显,正距平年数比例由70年代的10%上升至21世纪初的80%,西北干旱区整体处于相对湿润时段,且增湿趋势明显。     

Summer monsoon precipitation variations in central China over the past 750 years derived from a high-resolution absolute-dated stalagmite

A 2–3-year resolution record of stalagmite oxygen isotope variations from the south flank of the Qinling Mountains, central China, has revealed the Asian summer monsoon (ASM) precipitation variations in the investigated area over the past 750 years. The summer monsoon precipitation gradually increased since 1249 AD, reaching its highest values in the period 1535–1685 AD, and then decreased with substantial decadal- to centennial-scale fluctuations. The monsoon precipitation increased again between 1920 and 1970 AD. Three intervals of high monsoon precipitation were identified: 1535–1685 AD, 1755–1835 AD, and 1920–1970 AD. Three intervals of low precipitation were inferred in 1249–1325 AD, 1390–1420 AD, and 1890–1915 AD. The δ¹⁸O composition and lithological features of the stalagmite coincidently indicate a wetter climate during the Little Ice Age (LIA), which is also confirmed by climate records from Chinese historical documents within this area. A comparison with other high-resolution speleothem records indicates regional differences in monsoon precipitation variability from the south to the north of central China in the last 750 years on decadal- to centennial-scale. Power spectrum analysis of the δ¹⁸O record shows significant 117.8-, 34.6-, 14-, 10.3-, and ~ 6-year periodicities. These periodicities are widely observed in the climate records from ASM-controlled areas of China and are consistent with the Gleissburg periodicity, Brϋckner periodicity, sunspot periodicity of solar activity, and El Nińo–Southern Oscillation (ENSO) periodicity. These correlations suggest that both solar activity and ENSO periodicity may have had important influences on ASM precipitation in China over the past 750 years.     

近50年华南气象干旱时空特征及其变化趋势

采用标准化前期降水指数(SAPI)和常年平均相对湿润度指数(M)构建的逐日气象干旱指数(DI),根据华南(广东、广西)174个气象站资料分析了近50年(1961—2010年)气象干旱时空特征及其气候变化趋势。结果表明:(1)华南近30年(1981—2010年)总旱日频率平均为26.0%,其中轻旱、中旱、重旱和特旱日分别为12.3%、8.1%、4.2%和1.4%。(2)各等级旱日频率具有非汛期(10月至次年3月)高于汛期(4月至9月)、广西高于广东的特征。(3)近50年华南最旱的5a依次为:1963、1991、2004、2009、1977。(4)气候变化趋势分析表明,1至9月降水和月干旱指数(MI)以增加趋势为主,各等级旱日数以减少趋势为主,其中7月份MI增加趋势及各等级旱日减少趋势均达到0.1显著水平;而10至12月降水和MI以减小趋势为主,各等级旱日数以增加趋势为主,其中11月份MI减小趋势及中旱、重旱、总旱日增加趋势均达到0.05显著水平。(5)年总旱日趋于增加、减少的站点数各占60%、40%,有11%的站点达到0.1以上显著水平。各等级旱日显著增加的站点大多集中在广西,而旱日显著减少的站点主要集中在广东,表明广西干旱总体上重于广东的格局可能进一步加剧。目的为进一步开展华南气候变化影响评估、水资源利用及应对气候变化提供基础。     

Rapid genetic divergence in response to 15 years of simulated climate change

Genetic diversity may play an important role in allowing individual species to resist climate change, by permitting evolutionary responses. Our understanding of the potential for such responses to climate change remains limited, and very few experimental tests have been carried out within intact ecosystems. Here, we use amplified fragment length polymorphism (AFLP) data to assess genetic divergence and test for signatures of evolutionary change driven by long‐term simulated climate change applied to natural grassland at Buxton Climate Change Impacts Laboratory (BCCIL). Experimental climate treatments were applied to grassland plots for 15 years using a replicated and spatially blocked design and included warming, drought and precipitation treatments. We detected significant genetic differentiation between climate change treatments and control plots in two coexisting perennial plant study species (Festuca ovina and Plantago lanceolata). Outlier analyses revealed a consistent signature of selection associated with experimental climate treatments at individual AFLP loci in P. lanceolata, but not in F. ovina. Average background differentiation at putatively neutral AFLP loci was close to zero, and genomewide genetic structure was associated neither with species abundance changes (demography) nor with plant community‐level responses to long‐term climate treatments. Our results demonstrate genetic divergence in response to a suite of climatic environments in reproductively mature populations of two perennial plant species and are consistent with an evolutionary response to climatic selection in P. lanceolata. These genetic changes have occurred in parallel with impacts on plant community structure and may have contributed to the persistence of individual species through 15 years of simulated climate change at BCCIL.     

Impacts of climate change on forest growth in saline-alkali land of Yellow River Delta,North China

Climate change is an important factor affecting forest growth. Therefore, approaching the impacts of climate change on forest growth is of great significance to ameliorate this degraded land and push up forestry development. This paper initially probes the impacts of climate change on tree growth in Yellow River Delta region and responds of different tree species on the change. In this study, five species of 22-year-old trees were selected, and the tree biomass was measured by standard site methods and tree ring sampling to pursue the impacts of climate change on forest growth. Besides, growth models of the different tree species were established and verified using Robinia pseudoacacia as an example. The results showed: (1) In the Yellow River Delta, the most adapted tree species are Fraxinus chinensis and R. pseudoacacia. (2) Precipitation is the main meteorological factor affecting tree growth, while temperature and air pressure are also significantly correlated with tree growth. (3) Linear and power function models can simulate tree growth well. From the verification results, the modified R. pseudoacacia biomass is 294.54 t/ha, and the simulated biomass of the linear function model is close to the value. It is expected that the research not only provides a theoretical basis for forestry development in saline lands, but also helps to rehabilitate saline-alkali lands and cope with climate change.     

Characterizing differences in precipitation regimes of extreme wet and dry years: implications for climate change experiments

Climate change is intensifying the hydrologic cycle and is expected to increase the frequency of extreme wet and dry years. Beyond precipitation amount, extreme wet and dry years may differ in other ways, such as the number of precipitation events, event size, and the time between events. We assessed 1614 long‐term (100 year) precipitation records from around the world to identify key attributes of precipitation regimes, besides amount, that distinguish statistically extreme wet from extreme dry years. In general, in regions where mean annual precipitation (MAP) exceeded 1000 mm, precipitation amounts in extreme wet and dry years differed from average years by ~40% and 30%, respectively. The magnitude of these deviations increased to >60% for dry years and to >150% for wet years in arid regions (MAP<500 mm). Extreme wet years were primarily distinguished from average and extreme dry years by the presence of multiple extreme (large) daily precipitation events (events >99th percentile of all events); these occurred twice as often in extreme wet years compared to average years. In contrast, these large precipitation events were rare in extreme dry years. Less important for distinguishing extreme wet from dry years were mean event size and frequency, or the number of dry days between events. However, extreme dry years were distinguished from average years by an increase in the number of dry days between events. These precipitation regime attributes consistently differed between extreme wet and dry years across 12 major terrestrial ecoregions from around the world, from deserts to the tropics. Thus, we recommend that climate change experiments and model simulations incorporate these differences in key precipitation regime attributes, as well as amount into treatments. This will allow experiments to more realistically simulate extreme precipitation years and more accurately assess the ecological consequences.     

Soil microbial and nutrient responses to 7 years of seasonally altered precipitation in a Chihuahuan Desert grassland

Soil microbial communities in Chihuahuan Desert grasslands generally experience highly variable spatiotemporal rainfall patterns. Changes in precipitation regimes can affect belowground ecosystem processes such as decomposition and nutrient cycling by altering soil microbial community structure and function. The objective of this study was to determine if increased seasonal precipitation frequency and magnitude over a 7‐year period would generate a persistent shift in microbial community characteristics and soil nutrient availability. We supplemented natural rainfall with large events (one/winter and three/summer) to simulate increased precipitation based on climate model predictions for this region. We observed a 2‐year delay in microbial responses to supplemental precipitation treatments. In years 3–5, higher microbial biomass, arbuscular mycorrhizae abundance, and soil enzyme C and P acquisition activities were observed in the supplemental water plots even during extended drought periods. In years 5–7, available soil P was consistently lower in the watered plots compared to control plots. Shifts in soil P corresponded to higher fungal abundances, microbial C utilization activity, and soil pH. This study demonstrated that 25% shifts in seasonal rainfall can significantly influence soil microbial and nutrient properties, which in turn may have long‐term effects on nutrient cycling and plant P uptake in this desert grassland.     

近60年气候变化对天童地区常绿阔叶林净初级生产力的影响

基于天童地区1954-2009年日序列气象数据,采用周广胜NPP模型,研究了天童地区近60年气候变化规律及其对常绿阔叶林NPP的影响,结果表明:1)近60年,天童地区月平均气温、降雨量和月参考蒸散量(ET0)在7、8月份明显增加,年平均气温、降雨量和ET0增加趋势十分显著(P<0.001);2)天童地区常绿阔叶林56年NPP的平均值为12.196t.hm-2.a-1,近60年升高趋势极为显著(P<0.0001);3)未来温度升高2℃,降水量增加20%的情景下,该地区常绿阔叶林的NPP将升高15.9%。未来温度升高2℃,降水量减少20%的情景下,NPP将降低4.9%。未来温度升高2℃,降水量不变的情景下,NPP将增加5.5%;4)年降雨量、ET0年均值和年平均气温是影响NPP变化的主要因子。     

近50年武威市地气温差变化趋势及影响因子

利用1961—2010年甘肃省武威市4个气象站月平均0 cm地温、气温及年日照时数、蒸发、降水、相对湿度和平均风速等观测资料,运用趋势系数法系统分析了该区域近50 a地气温差的时空分布特征,采用相关系数法和多元线性回归中的标准化回归系数分析了影响地气温差的气象因子。结果表明武威市地气温差的空间分布与地表植被、地层岩性、土层含水量等局域性因素有关,中部绿洲平原最大,北部荒漠区最小。月变化中,夏半年较大,6月最高;冬半年较小,12月最低。季节变化趋势不太一致,春夏季均呈上升趋势;秋季中北部上升,浅山区下降;冬季(除北部荒漠区外)均呈下降趋势。年和年代际变化总体呈上升趋势,中北部较显著;年平均地气温差的时间序列存在着5—7 a的准周期变化,并在2004年发生了突变。年地温、气温均呈升高趋势,年地气温差与地温、气温呈正相关。影响地气温差的主要因子是最高地温、蒸发量和降水量。地气温差与平均最高地温、平均最低气温和日照时数均呈正相关,但与蒸发、降水、相对湿度和平均风速均呈负相关。     

The effects of land use and climate change on the carbon cycle of Europe over the past 500 years

The long residence time of carbon in forests and soils means that both the current state and future behavior of the terrestrial biosphere are influenced by past variability in climate and anthropogenic land use. Over the last half‐millennium, European terrestrial ecosystems were affected by the cool temperatures of the Little Ice Age, rising CO₂ concentrations, and human induced deforestation and land abandonment. To quantify the importance of these processes, we performed a series of simulations with the LPJ dynamic vegetation model driven by reconstructed climate, land use, and CO₂ concentrations. Although land use change was the major control on the carbon inventory of Europe over the last 500 years, the current state of the terrestrial biosphere is largely controlled by land use change during the past century. Between 1500 and 2000, climate variability led to temporary sequestration events of up to 3 Pg, whereas increasing atmospheric CO₂ concentrations during the 20th century led to an increase in carbon storage of up to 15 Pg. Anthropogenic land use caused between 25 Pg of carbon emissions and 5 Pg of uptake over the same time period, depending on the historical and spatial pattern of past land use and the timing of the reversal from deforestation to afforestation during the last two centuries. None of the currently existing anthropogenic land use change datasets adequately capture the timing of the forest transition in most European countries as recorded in historical observations. Despite considerable uncertainty, our scenarios indicate that with limited management, extant European forests have the potential to absorb between 5 and 12 Pg of carbon at the present day.     

中国东部南北样带主要植被类型归一化植被指数对气候变化的响应及不同时间尺度的差异性

植被的动态变化及其与环境的关系已成为全球变化研究的热点问题。陆地样带是进行全球变化驱动因素梯度分析的有效途径。该研究依托中国东部南北样带(NSTEC), 对南北样带不同时间尺度的气候因子和植被活动变化特征进行了分析, 并重点阐述了具有代表性的12种植被类型对气候因子的响应方式。研究结果表明: 南北样带植被的归一化植被指数(NDVI)的变化同时受控于气温和降水, 但是在不同的空间和时间尺度上植被NDVI的响应方式各异。在年时间尺度上, 只有温带落叶灌丛(TDS)的NDVI受气温控制; 而温带禾草草原(TGS)和亚热带和热带针叶林(STCF)的NDVI同时受气温和降水调控。其他植被类型的年NDVI与年平均气温和年总降水量没有直接显著的联系, 而受年内气温变化和降水分配状况的影响更大。在月时间尺度上, NDVI与气温的关系在不同类型植被之间存在很大差异。一般而言, 植被NDVI与前4个月内的气温关系最为密切, 并且从1月份到4月份气温的滞后时长在缩短。其中, 温带针叶林(TCF)、温带落叶阔叶林(TDBF)、TDS、STCF和亚热带热带草丛(STG)等植被类型, 5-8月的NDVI与气温普遍呈负相关关系。草原和灌丛植被类型当月NDVI与当月降水量主要以正相关为主, 而森林类型当月NDVI与当月降水量主要以负相关为主。     

景观格局的影响——以新疆玛纳斯河流域为例

国家重点基础研究发展计划资助项目（2009CB825105）;中国科学院研究生科技创新与社会实践资助专项（2009）;中国科学院“西部之光”人才培养计划资助项目(XBBS200903)