中国温带草原和荒漠区域春季物候的变化及其敏感性分析

[目的]在全球气候变化背景下,分析中国温带草原和荒漠区域春季物候变化趋势,探索该区域春季物候与气候因子之间的关系。[方法]利用1982—2015年归一化植被指数(NDVI)数据集,提取中国温带草原和荒漠区域植被生长季开始日期(SOS),评估整个研究区及草甸、草原和荒漠SOS的线性趋势。利用偏相关和多元线性回归方法,分析SOS与季前(5月—上一年11月)温度和季前降水的关系,并分析SOS对气候变化响应的空间模式。[结果]1982—2015年中国温带草原和荒漠区域SOS以0.14d·a^-1的速率显著提前。空间上,68%的地区呈提前趋势,32%的地区呈延迟趋势。SOS与不同季前时期的平均温度和降水均呈负相关,且与季前平均温度的相关性更显著。SOS分别与季前40d平均温度和季前200d降水的相关性最大。1982—2015年,季前(40d)平均温度上升1℃,SOS显著提前1.31d;季前(200d)降水增加10mm,SOS提前0.44d。空间上,长期平均季前(200d)降水增加10mm,SOS温度敏感性增加0.093d·℃^-1,SOS降水敏感性降低0.019d·10mm^-1。[结论]过去34年中国温带草原和荒漠区域SOS表现提前趋势。季前平均温度是控制SOS变化的主要因子。季前平均温度升高和季前降水增加会导致SOS提前。季前降水决定SOS温度敏感性和SOS降水敏感性的空间格局。季前降水越多的地区,SOS对季前平均温度越敏感;季前降水越少的地区,SOS对季前降水越敏感。

水热条件分别控制了中国温带草地NDVI的年际变化和增长趋势

温带草地区是我国植被对气候变化响应的敏感区和陆地生态系统的生态脆弱区,是组成草地资源的重要部分。由于全球变暖,气候变化带来的极端气候影响越来越大,探究我国温带草地植被覆盖时空变化规律和水热条件变化对其生长的影响,对区域生态的环境保护,实现畜牧业的可持续发展和更加合理有效地利用草地资源具有重要的现实意义。基于1982—2015年长时间序列的气象(降水、温度、太阳辐射)数据和GIMMS NDVI 3g数据,采用去趋势分析法和相关性分析法,探究近34年中国温带地区生长季草地归一化植被指数(Normalized difference vegetation index,NDVI)和气候因子变化格局,以及水热条件对NDVI的同步影响和滞后影响。研究结果表明:(1)1982—2015年中国温带草地生长季平均温度和月平均太阳辐射呈增长趋势,降水量为下降趋势,温带草地气候逐渐呈现“暖干化”;(2)1982—2015年中国温带草地生长季NDVI的年际变化由降水因子主导,特别是在1999年之后,降水的对于中国温带草地生长季NDVI年际变化的影响更为显著;(3)1982—2015年中国温带草地生长季NDVI为增长趋势,生长季热条件(温度和太阳辐射)的显著上升控制着NDVI的增长趋势;(4)1982—2015年中国温带草地生长季NDVI对水热因子在年际变化上存在明显的滞后响应,生长季前期NDVI对温度滞后响应最明显,生长季中后期降水则成为植被生长滞后影响的主要控制因子。

1982—2015年中国温带地区夏季植被长势对生长季结束日期的影响

基于1982—2015年GIMMS NDVI3g数据,利用累计NDVI的Logistic曲线曲率极值法识别中国温带生长季结束日期(End of Growing Season,EOS),并在空间上及不同植被类型上分析了夏季植被长势对生长季结束日期的影响。结果表明:研究期间,中国温带地区的夏季平均NDVI值主要分布在0.05~0.91之间,生长季结束日期主要集中在第231~313 d之间。在空间上,夏季NDVI与生长季结束日期呈负相关的区域占总面积的64.9%,显著负相关达20.7%,主要分布在新疆天山以南地区、青藏高原地区及内蒙古地区;而呈正相关关系的面积占全区35.1%,主要分布在研究区的东北部和东南部、新疆天山以北地区及青藏高原中部少数地区。从植被类型上看,森林植被类型(寒温带针叶林、暖温带落叶阔叶林、混交林)的夏季NDVI与生长季结束日期呈正相关,而在温带草原、青藏高原高寒植被、温带荒漠上与生长季结束日期呈负相关,这表明在干旱的生态系统类型上(温带草原、青藏高原高寒植被、温带荒漠),夏季植被长势旺盛导致生长季结束日期提前,而夏季植被的退化会推迟生长季结束日期。同时,气象因子作为植被生长发育的重要环境因子对生长季结束日期的变化起到重要作用。

中国温带昼夜增温的季节性变化及其对植被动态的影响

结合1982-2015年归一化植被指数(NDVI)、植被类型和气象数据,分别利用一元线性回归和二阶偏相关分析方法,揭示了中国温带地区的生长季不同季节昼夜增温的时空格局以及昼夜增温的不对称性对各类型植被活动的影响。结果表明:(1)近34年来中国温带大部分地区季节性昼夜气温都存在显著的上升趋势;生长季昼夜增温速率呈现出不对称性,春季、夏季白天气温上升速度略快于夜间,秋季夜间增温快于白天;(2)不同季节的昼夜增温对植被活动的影响呈现出明显的分异特征,相对于夜间增温,白天增温对植被活动影响程度更大,影响区域更为广泛;相比夏季和秋季,春季昼夜增温对植被活动的影响范围更广;(3)不同类型植被对昼夜增温速率的不对称性产生了不同的响应,并且在不同季节上的响应程度存在差异。

中国温带地区植被物候期时空变化特征及对总初级生产力的影响

陆地表面物候(Land Surface Phenology,LSP)被定义为陆地表面植被的生命周期事件在区域或全球尺度上的各季节时间,对于中国温带地区的植被物候,已有研究大多仅针对某一地区的单一植被类型,对长时间、大尺度的陆表物候时空变化的研究较为少见,植被物候对总初级生产力(Gross Primary Productivity,GPP)的影响也有待明确。采用2001～2014年中等分辨率成像光谱仪MODIS的MCD12Q2数据以及MOD17A3 GPP数据,利用回归分析以及相关分析的方法对中国温带地区(>30°N)植被物候期时空变化特征进行分析,并研究物候变化对GPP的影响。结果表明:我国温带地区整体植被生长季开始日期(Start of the Season,SOS)、结束日期(End of the Season,EOS)和生长季长度(Length of the Season,LOS)的14 a平均值和标准差分别为第121±10 d、第270±12 d和153±12 d;SOS提前趋势(r=-0.36,p=0.21)、EOS滞后趋势(r=0.41,p=0.15)与LOS增长趋势(r=0.51,p=0.06)均不明显;但是年均LOS与GPP相关性显著(r=0.74,p=0.002 5),且呈正相关关系。2001～2014年LOS与GPP年均值的空间分布均呈现出由西北向东南增加的趋势;研究区SOS、EOS与LOS的年际变化呈现显著变化(p<0.05)的地区分别占研究区的13%、21%、13.2%。SOS、EOS、LOS与GPP显著相关(p<0.05)的地区分别占研究区的8.31%、9.33%、8.72%,三者与GPP的相关关系均以中度相关为主(p<0.05,0.5<|r|<0.8),二者高度相关(p<0.05,|r|≥0.8)的地区很少。研究区植被物候期变化显著影响(p<0.05)植被年均GPP的地区仅有4.29%。

植物生活型分类系统的修订及中国暖温带森林植物生活型谱分析

根据中国暖温带森林植物习性，修订了Ｒａｕｎｋｉｅａｒ的生活型分类系统。通过对暖温带森林植物生活型谱的分析，证明暖温带森林群落植物生活型谱以地面芽为主，其次是地下芽。受水、热不足和人为活动频繁等条件的限制，暖温带地区缺乏或极少有高于２５ｍ的大高位芽植物；中高位芽、小高位芽和矮高位芽植物所占的比重与地面芽植物近似，其中落叶阔叶高位芽植物占有绝对的优势。主要由上述生活型所构成的暖温带森林植物生活型谱，基本反映了我国暖温带森林区夏季温暖多雨、冬季寒冷干旱的中纬度气候特征。

中国温带荒漠植物群落生态特异性格局及其影响因素

局域取样单元对beta多样性的贡献可用于测度每个局域群落物种组成的生态特异性(ecological uniqueness)。温带荒漠生态系统广泛分布于全球干旱和极端干旱区域,极易受到气候变化和人类活动的影响。然而目前温带荒漠植物群落生态特异性大尺度地理分布格局及其形成机制的系统研究还很缺乏,制约着我们对荒漠植物群落多样性维持机制的认知。本文在温带灌木、矮半乔木及草原化灌木荒漠等6个中国温带荒漠区的主要地带性植被类型中设置了948个样方,通过开展系统的野外调查采样和室内分析,以及量化每个取样单元对beta多样性的贡献,并结合土壤和气候变量等环境数据,探讨了中国荒漠植物群落生态特异性大尺度地理分布格局及其影响因素。结果表明:(1)温带荒漠植物群落生态特异性存在显著的经度、纬度和海拔分布格局,随着经度增加显著降低,但随着纬度或海拔的升高呈现出先下降后增加的变化趋势;(2)土壤、气候、群落特征(植物物种丰富度和群落盖度)对植物群落生态特异性都有着显著的单独影响,植物群落生态特异性随着物种丰富度增加呈先下降后上升的变化趋势;经度、土壤、气候和植物群落特征共同解释了温带荒漠植物群落生态特异性33.5%的空间变异,其中气候因子有着更强的单独解释率。上述结果说明环境过滤和中性过程以及其他未知过程共同调控了温带荒漠植物群落的生态特异性大尺度分布格局的形成,且气候和土壤因素的过滤作用有着重要影响。

美国中东部温带稳定≥10℃积温

应用修订的康拉德公式计算美国中东部温带地区日均温稳定≥10℃积温,并同我国相应纬度地区作了对比。这一对比揭示出我国东部温带并非世界同纬度地带夏半年热量资源最丰富。

安徽大别山粒毛盘菌初探

大别山区森林植物极其丰富多样,区内气候温暖湿润,为粒毛盘菌等腐生真菌生长提供了丰富的基物和适宜的气候条件。对该地区粒毛盘菌等相关类群资源进行了研究,报道了粒毛盘菌属7个分类单元,包括Lachnumciliare,L.nudipes,L.pudibundum,L.pygmaeum,L.subpygmaeum,L.sichuanense和L.virgineum,利用物种描述式表明了种的主要特征,并对其中部分种进行了形态学方面的讨论。

黄河三角洲湿地研究进展

黄河三角洲湿地是目前世界上土地面积自然增长最快的地区之一，是中国暖温带保存最完整、最广阔、最年轻的湿地生态系统，无论其在中国经济发展上，还是在环境建设上都具有重要的地位，由于其湿地生态系统的原始性和作为珍稀濒危鸟类重要栖息地的作用，在国际上也备受关注。

Diurnal and Seasonal Dynamics of Soil Respiration at Temperate Leymus Chinensis Meadow Steppes in Western Songnen Plain, China

To evaluate the diurnal and seasonal variations in soil respiration （Rs） and understand the controlling factors, we measured carbon dioxide （CO2） fluxes and their environmental variables using a LI-6400 soil CO2 flux system at a temperate Leymus chinensis meadow steppe in the western Songnen Plain of China in the growing season （May-October） in 2011 and 2012. The diurnal patterns of soil respiration could be expressed as single peak curves, reaching to the maximum at 11：00-15：00 and falling to the minimum at 21：00-23：00 （or before dawn）. The time-window between 7：00 and 9：00 could be used as the optimal measuring time to represent the daily mean soil CO2 efflux. In the growing season, the daily value of soil CO2 efflux was moderate in late spring （1.06-2.51μnol/（m2.s） in May）, increased sharply and presented a peak in summer （2.95-3.94 μmol/（m2.s） in July）, and then decreased in autumn （0.74-0.97 μmol/（m2.s） in October）. Soil temperature （Ts） exerted dominant control on the diurnal and seasonal variations of soil respiration. The temperature sensitivity of soil respiration （Q10） exhibited a large seasonal variation, ranging from 1.35 to 3.32, and decreased with an increasing soil temperature. Rs gradually increased with increasing soil water content （Ws） and tended to decrease when Ws exceeded the optimum water content （27%） of Rs. The Ts and Ws had a confounding effect on Rs, and the two-variable equations could account for 72% of the variation in soil respiration （p 〈 0.01）.

山东黄河三角洲国家级自然保护区

黄河三角洲主要是指1855年以来黄河铜瓦厢决口改道夺大清河入海后形成的三角洲，位于山东省北部莱州湾和渤海湾之间。黄河三角洲湿地是由黄河携带大量泥沙填充渤海淤积而成的，面积不断增加，形成了中国暖温带最年轻、最广阔、保存最完整的湿地生态系统，是我国乃至世界最具代表性和典型性的河口湿地。

Characteristics of Oxides in Argillic Soils of Warm Tem-perate Zone in China

Studies of seven typical soil profiles showed that in the argillic soils derived from loess in the warmtemperate zone of China all the oxides of Fe, Mn, Al and Si were enriched with the accumulation of clayfraction in the profiles. But owing to the influence of oxidation-reduction process the migration velocity ofFe and Mn was faster than that of clay. The free degrees of those metals were in the sequence Mn>Fe>Al,which reflected their different chemical activities in soil. In soils at the same level of development, the freedegree of iron and its activity, the free degree of Al, Alo/Alt× 100, SiO_2/R_2O_3, Sio/Sit× 100, and themagnetic susceptibility were relatively close to each other respectively. It might be considered that both thefres degrees of Fe and Al and Alo/Alt× 100 could serve as the distinctive indexes for argillic soils in warmtemperate zone. The paleoclimate corresponding to the fifth layer of paleosol (s_5) in Lnochuan, Shaanxiwas warmer and more humid than the present, and the paleoecological landscape approximated to today'sbioclimatic belt between the temperate deciduous broadleaved forest and the semiarid forest types.The Mossbouer spectra of the colloidal fraction (<1um) in the clayified horizon of argillic dark loessialsoil, cinnamon soil, brown earth and (s_5) paleosol indicated the superparamagnetic state at room temperature.The magnetic splitting six line spectra were observed clearly at 80 K. The results fitted with a computershowed that hematite and goethite were predominant in iron oxides and commonly existed as fine particles.The proportion of hematite and goethite in soil colloids varied considerably with different climates. Thehigher the temperature, the larger the proportion of hematite.

Synedra ulna var.repanda,a new variety of Synedra (Bacillariophyta) from Xinjiang,China

Synedra ulna var, repanda Q. X. Wang ＆ Q. M. You, a new variety of Synedra （Bacillariophyta） from Xinjiang, China, is described and illustrated, and the characteristic of the variety： includes undulate-linear valves and straight pseudoraphe, differs from other species of Synedra.

伊犁六大特色天然树种

1新疆杨（Populusalba var．pyramidalis Bge）杨柳科，杨属，白杨派。中国暖温带大陆性气候区主栽树种，新疆栽培最早，分布亦最为普遍。新疆杨生长快，材质好，抗性强，适宜在伊犁河谷城乡庭院和水土条件较好的农田栽培。伊犁因此树生长参天、整齐而得“白杨城”之名。

Genetic Parameters for Yields and Reproductive Traits of Chinese Holstein Cows in Heilongjiang Province

[Objective] This study aimed to estimate the genetic parameters for milk yield, fat percentage, fat yield and age at first freshening of Chinese Holsteins first lactation cows in Heilongjiang under frigid-temperature and temperature zone. [Method] Records of yield and reproduction from 8 868 Chinese Holstein first lacta- tion cows from 21 herds were utilized to evaluate genetic parameters for Hei- Iongjiangs＇ Chinese Holsteins. Restricted maximum likelihood （REML） method was used with an animal model. [Result] The heritabilities were 0.16 to 0.34 for yields and fat percentage, 0.38 for reproduction （age at the first freshening）, which were similar to estimates for temperate areas from similar methods, except for constituent percentage. Also, the estimates of genetic correlation were high between milk yield and fat yield （0.97）, but were low between milk yield and fat percentage （-0.24）, age at the first freshening （-0.29） and generally antagonistic. [Conclusion] Thus, es- timates of genetic parameters in this frigid and frigid-temperate environment did not differ appreciably from those that occur in temperate dairy areas.

Characteristics of Tropical Sea Surface Temperature Anomalies and Their Influences on the Onset of South China Sea Summer Monsoon

The characteristics of sea surface temperature anomalies （SSTAs） in the tropical oceans and their influences on the onset of South China Sea summer monsoon （SCSSM） have been studied.The anomaly of SST in tropical Pacific Ocean exerts persistence impact for one to three months on atmospheric circulations.If the warm pool becomes anomalously warmer during an earlier period from February to April,the SCSSM breaks out earlier,and vice versa.Singular value decomposition （SVD） and composite analysis have shown that,in La Ni（n）a pattern,the convection over Western Pacific will occur earlier and be stronger than normal,which favors the convergence at a lower layer over Western Pacific,as well as the strengthening of upwelling branch of Walker circulation,leading to an earlier burst of westerly in the southern South China Sea.Moreover,the convection in Sumatra appears earlier than normal and favors the westerly evolution in eastern Indian Ocean,resulting in the splitting of the subtropical high belt and an early onset of SCSSM.However,the atmospheric circulation anomaly is reversed in El Ni（n）o pattern.

Holocene vegetation succession and responses to climate change in the northern sector of Northeast China

Sediment pollen samples from the Huola Basin in the northern sector of northeast China, and surface pollen samples from its environs, were analyzed to reconstruct accurately the historical response of vegetation to climate change since 9100 cal yr BP. Pollen analysis of the Huola Section indicates that vegetation experienced a transformation from early-mid Holocene warm-cold mixed vegetation to late Holocene cold-temperate vegetation. From 9100 to 6000 cal yr BP, the study area was warmer and moister than at present, developing Corylus, Carpinus, Pinus, Picea, Betula and Larix-dominated forests. Two cooling events at 6000–5000 and 3500–2500 cal yr BP led to a decrease in Corylus, Carpinus and other warmth-loving vegetation, whereas cold temperate forests composed of Larix and Betula expanded. After 2500 cal yr BP, Larix and Betula dominated cold-temperate vegetated landscapes. The Holocene warm period in NE China(9100–6000 cal yr BP) suggests that such warming could have resulted in a strengthening of the influence from East Asian Summer Monsoon on northernmost NE China and would have benefited the development of warm-temperate forest vegetation and an improved plant load, which also provides the similarity model for the possible global warming in the future.

Spatial modeling of the Ulmus pumila growing season in China's temperate zone

To reveal the ecological mechanism of spatial patterns of plant phenology and spatial sensitivity of plant phenology responses to climate change,we used Ulmus pumila leaf unfolding and leaf fall data at 46 stations of China's temperate zone during the period 1986-2005 to simulate 20-year mean and yearly spatial patterns of the beginning and end dates of the Ulmus pumila growing season by establishing air temperature-based spatial phenology models,and validate these models by extensive spatial extrapolation.Results show that the spatial patterns of 20-year mean and yearly February-April or September-November temperatures control the spatial patterns of 20-year mean and yearly beginning or end dates of the growing season.Spatial series of mean beginning dates shows a significantly negative correlation with spatial series of mean February-April temperatures at the 46 stations.The mean spring spatial phenology model explained 90% of beginning date variance(p<0.001) with a Root Mean Square Error(RMSE) of 4.7 days.In contrast,spatial series of mean end dates displays a significantly positive correlation with spatial series of mean September-November temperatures at the 46 stations.The mean autumn spatial phenology model explained 79% of end date variance(p<0.001) with a RMSE of 6 days.Similarly,spatial series of yearly beginning dates correlates negatively with spatial series of yearly February-April temperatures and the explained variances of yearly spring spatial phenology models to beginning date are between 72%-87%(p<0.001),whereas spatial series of yearly end dates correlates positively with spatial series of yearly September-November temperatures and the explained variances of yearly autumn spatial phenology models to end date are between 48%-76%(p<0.001).The overall RMSEs of yearly models in simulating beginning and end dates at all modeling stations are 7.3 days and 9 days,respectively.The spatial prediction accuracies of growing season's beginning and end dates based on both 20-year mean and yearly models are close to the spatial simulation accuracies of these models,indicating that the models have a strong spatial extrapolation capability.Further analysis displays that the negative spatial response rate of growing season's beginning date to air temperature was larger in warmer years with higher regional mean February-April temperatures than in colder years with lower regional mean February-April temperatures.This finding implies that climate warming in winter and spring may enhance sensitivity of the spatial response of growing season's beginning date to air temperature.

Soil Respiration in a Subtropical Mangrove Wetland in the Jiulong River Estuary, China

The diurnal and seasonal variations of soil respiration （SR） were studied at a subtropical mangrove wetland in the Jiulong River Estuary from May 2010 to April 2011. SR rates were measured continuously from 08：00 to 06：00 local time （24-h time system） on July 8-9 and October 3-4, 2010; and January 15-16 and April 11-12, 2011. Similar patterns in the diurnal variation of SR were observed on October 2-3 and April 11-12, with the maximum values at 14：00 and the minimum at 00：00. However, the diurnal dynamics of SR on July 8-9, 2010 and January 15-16, 2011 showed different patterns, with the maximum values at 08：00-10：00 on above sampling dates and the minimum at 22：00 on July 8 and at 04：00 on January 16. The daily mean values of SR approximated to the values measured at 08：00. SR fluctuated with distinct seasonal patterns. The seasonal variation was characterized by a mono-peak pattern, with the highest rate （6.18 ~mol CO2 m-2 s-1） in July and the lowest rate （0.36 ~tmol CO2 m-2 s-1） in December. The results showed that the variation of SR in mangrove wetland was mainly controlled by soil temperature, and there was no significant correlation between SR and soil water content. It also implied that the model of SR in mangrove wetland should not only consider the effect of soil temperature, but also incorporate other factors, such as water level, precipitation, microbial activity and photosynthesis, which also could affect SR.