雅鲁藏布江河岸植物物种丰富度分布格局及其环境解释

沿环境梯度物种多样性的分布格局及其环境影响因子的研究是生态学研究的重点内容之一。雅鲁藏布江是我国海拔最高的大河, 目前还没有针对其流域的河岸植物群落物种丰富度分布格局的系统研究。作者沿海拔梯度从雅鲁藏布江上游源头区至下游共设置了15个海拔样带, 在每个海拔样带随机取6个5 m×5 m样方, 共对90个样方的河岸植物群落物种组成和植被类型进行了调查, 共记录到238种维管束植物。DCA排序结果表明物种组成变化主要受海拔和经度控制。CCA排序区分出5种大的植被类型, 即高寒草甸或高寒草原、高山草原、两种亚高山灌丛草原和林缘灌丛植被。各植被类型的分布和变化主要受海拔和经度影响。雅鲁藏布江河岸植物物种丰富度沿海拔和经度梯度呈浅“U”形分布格局, 物种丰富度与年均降水量和植被盖度成显著正相关。     

不同海拔梯度高寒草地地上生物量与环境因子关系

以新疆天山南坡的巴音布鲁克高寒草地为研究对象,沿海拔每升高100m设置1块样地,共9个样地,研究了海拔梯度变化条件下高寒草地地上生物量与环境因子的关系.研究表明:紫花针茅、羊茅群落分布在海拔2460～2760m,地上生物量为52.2～75.9g.m-2,线叶嵩草 紫花针茅群落分布在海拔2860m,地上生物量为53.2g.m-2,线叶嵩草、天山羽衣草、细果苔草群落分布在海拔2960～3260m,地上生物量为62.1～107.4g.m-2;7—8月平均相对湿度对群落总的地上生物量影响较大;海拔与禾本科的地上生物量呈显著负相关,与莎草科呈显著正相关;7—8月平均气温是决定禾本科和莎草科功能群地上生物量的主导因子,回归方程分别为Y=13.467X-97.284和Y=171.699-15.331X;海拔与平均气温和pH值呈极显著负相关(P<0.01),与平均相对湿度呈极显著正相关(P<0.01),与速效N含量和土壤含水量呈显著正相关(P<0.05).     

内蒙古草地样带植物群落生物量的梯度研究

 采用样带法对内蒙古草地植物群落生物量沿水热梯度的变化特征进行了研究,并对几种回归方法进行了比较。一元回归结果表明：在本样带的限定范围内,生物量与年均温、≥ 0 ℃年积温、≥10 ℃年积温、年实际日照总时数等热量因子呈负相关（年均温的相关性最高）,而与年降水量、年均相对湿度等水分因子呈正相关（年均相对湿度的相关性最高）,其中年均温和年均相对湿度对生物量的影响最为显著,二者对生物量的空间变异起着互为消长的作用,而海拔高度的影响则不显著。多元回归结果表明,作为半干旱区植物生长的主要限制因子,年降水量在大尺度上对生物量产生影响的途径更为复杂,但其作用不可低估。生物量和地下地上生物量比值会因不同的气候区、不同的植被类型和物种组成,对环境因子的响应程度不同,在经向、纬向和草地类型梯度上的变化特征也不同。水热的配比关系要比单一的水分和温度与植物的生长具有更紧密的关系,地下地上生物量比随着水热配比关系的变化也会呈现出不同的变化规律,其驱动因子并不一定始终都是降水。也许可以认为：半干旱/干旱的划分界限是本研究所涉及的草地样带上生物量和地下地上生物量比值沿草地类型梯度变化的一个转折界限,在此界限前后,气候对生物量的主导因素和生物量对此关键因子的响应程度都有所变化。     

中国区域植被地上与地下生物量模拟

应用大气-植被相互作用模型AVIM2在0.1°×0.1°经纬度网格上估算了中国区域植被总生物量、地下和地上生物量以及根茎比的空间分布格局。研究了植被生物量和根茎比的空间分布与水热限制条件的关系。研究表明:中国植被总生物量、地下和地上生物量受水热条件影响明显,空间分布趋势基本相似,即在暖湿的东南和西南地区生物量大,而在干冷的西部地区生物量小。同类植被生物量的空间分布有显著区域差异,气温高、降水量大的区域植被生物量大;低温和干旱地区的植被生物量小。除灌木以外,植被生物量大小的空间分布受水分的影响大于温度。中国区域植被根茎比的空间分布存在明显区域差异,全国大致以大兴安岭、太行山、秦岭以及青藏高原东南侧一线为界线,界线东南植被根茎比较小;界线以西,植被根茎比较大。植被根茎比的空间分布与年平均气温、土壤湿度和年降水量显著反相关,水分因子对根茎比空间分布的影响大于温度。     

三江并流地区干旱河谷植物物种多样性海拔梯度格局比较

在滇西北三江并流地区典型干旱河谷段, 在怒江、澜沧江和金沙江的东、西坡共设置了6条海拔梯度样带, 通过标准样地的植物群落调查, 分析各条样带植物的物种丰富度、物种更替率的海拔梯度格局, 并比较了地理和植被变量对分布格局的解释。干旱河谷植被带位于海拔3,000 m以下, 以灌丛和灌草丛为主, 其在各河谷的分布上限自西向东依次升高。植物物种丰富度的分布主要与海拔、流域、经纬度和植被带有关, 沿纬度和海拔梯度升高而显著增加的格局主要表现在草本层和灌木层, 灌木物种丰富度还呈现自西向东显著增加的趋势。怒江的灌木和草本种物种丰富度显著高于金沙江和澜沧江, 三条江的乔木种丰富度差异则不显著。森林带的样方草本物种丰富度显著低于灌草丛带样方, 并且还拥有后者没有的乔木种。不同样带的植物物种更替速率呈现了不一致的海拔梯度格局, 但均在样带海拔下部的灌草丛群落与海拔上部森林群落之间的交错带出现峰值。森林-灌草丛植被交错带在怒江样带处于海拔1,900-2,100 m处, 在澜沧江河谷位于海拔2,300-2,400 m, 在金沙江河谷位于海拔2,700-2,900 m。所有海拔样带的森林段或灌草丛段相对于同一样带不同植被段之间的物种更替程度为最小, 不仅小于同一流域不同样带相同植被段之间物种更替率的均值, 更小于所有样带相同植被段之间的更替率均值。在三条河流6条海拔样带的12个植被带段之间的物种更替变化中, 空间隔离因素可以解释34.2%, 而植被类型差异仅能解释不到0.5%。本研究结果显示了环境差异对不同植被类型物种丰富度的首要影响, 和各河流之间的空间隔离对植物群落构建和物种构成的主要作用。     

乌兰巴托-锡林浩特样带草地植被特征与水热因子的关系

2012年夏季,研究人员对蒙古高原长约1100km的乌兰巴托—锡林浩特草地样带开展考察,获取了46个样地的物种数量、地上生物量等数据;基于全球GHCN(全球历史气象网络)数据集,提取了样带夏季(6—8月)月均温度和降水总量;继而根据自然地理和行政区边界,将草地样带大致分成北部(蒙古国乌兰巴托—蒙古国艾日格)、中部(蒙古国艾日格—中国苏尼特左旗)和南部(中国苏尼特左旗—中国锡林浩特),开展了分析。研究表明:(1)样带夏季平均温度的空间分布形态呈现明显的倒"U"型分布,南北两端温度较低,中部温度较高;夏季降水量在空间上的分布形态则与之相反,呈现南北两端降水量较高,中部降水量较低的正"U"型分布;(2)样带上植物物种数量、地上生物量的空间分布形态均呈现正"U"型分布,即在生态景观类型为典型温性草原的样带南部和北部地区,其生物多样性、地上生物量明显好于呈现为温性荒漠草原、温性荒漠景观的样带中部地区。(3)相关分析体现了大尺度(高原样带尺度)上植被特征与水热环境因子间的关系:植物物种数量、地上生物量与夏季月均温度均呈现负相关,而与夏季降水总量则呈现正相关关系。(4)偏相关分析反映了局地小尺度上植被特征与水热环境因子间的关系:温度和降水要素对于植物物种数量、地上生物量均呈现正相关。     

拉萨河流域亏组山植物物种丰富度和群落特征研究

为研究草地植物群落、物种丰富度及其分布格局与影响因子之间的关系,该文以拉萨河流域林周县卡孜乡亏组山为研究地点,对山体垂直样带(3900~5100 m)植物群落特征、植物物种丰富度与各影响因子之间的关系进行了研究。研究区域共设置了13个样带(每隔100 m设一个样带),每样带设置0.5 m×0.5 m的5个样方进行植被调查,运用主成分分析(PCA)和双向指示种分析法(TWINSPAN)对植物群落进行排序和分类,运用冗余分析法(RDA)对群落及其分布格局与影响因子之间的关系进行分析,对植物物种丰富度与各因子之间的关系进行了回归分析。结果表明:该山体植物可分为3个群落类型,含7个群丛;影响区域植物群落物种组成和分布格局的主要环境因子为海拔,其次是坡度;物种丰富度与海拔、分种盖度呈单峰关系,与总盖度、坡度、地上生物量呈正相关。该研究结果为区域植物物种多样性和山地植物资源的保护和可持续利用提供了科学依据。     

中国亚热带灌丛植物生活型组成及其与水热因子的相关性

灌丛是亚热带一种重要的自然植被类型,有关其植物生活型方面的研究资料较少。该文采用分层随机抽样方法布设688个样点,系统调查了亚热带常绿阔叶林区域内灌丛维管植物生活型组成,分析其生活型谱特征、地理格局及其与水热因子间的关系。研究发现:(1)亚热带灌丛中,木本植物种数占总种数的56.37%,其中落叶和常绿木本植物种数各占33.88%和22.49%;草本植物占43.63%,以多年生草本为主,占35.15%;生活型组成以高位芽植物为主,其次为地面芽植物,生活型谱表现为高位芽植物地面芽植物一年生草本隐芽植物地上芽植物。(2)植物生活型主要表现为经度和海拔格局;高位芽植物随经度增加逐渐增多,地面芽植物、隐芽植物和一年生植物随经度增加而减少;地面芽植物和隐芽植物随海拔升高而逐渐增加,高位芽植物、地上芽植物和一年生植物随海拔升高而逐渐减少。(3)气候因子中,最热月平均气温和最冷月降水量与高位芽植物、地面芽植物、隐芽植物和一年生植物的相关性最大;随着最热月平均气温的升高和最冷月降水量增多,高位芽植物比例增加,地面芽植物、隐芽植物和一年生植物减少;最热月平均气温和最冷月降水量可解释亚热带灌丛生活型谱地理格局变异的41.97%,其中28.35%由两者共同贡献。研究结果表明:高位芽植物和地面芽植物受温度和降水共同影响,隐芽植物对温度梯度的反应更加灵敏,一年生植物对降水的响应更加强烈,地上芽植物不随水热梯度发生大的波动;最热月平均气温和最冷月降水量是影响灌丛植物生活型谱地理格局最重要的水热因子。     

天山中段主要植被类型中种群的空间分布格局与环境的关系

 用生物地理统计学的空间相关图及空间相关指数方法研究了天山中段主要植被类型中种群的空间分布格局及其影响种群空间分布格局的主要环境因子。主要考虑了山地荒漠、亚高山草甸和高山草甸3种植被类型,以及30年平均降水量和月平均气温、海拔、土壤pH值和有机质含量等9种环境及气象因子。结果表明：影响天山北坡荒漠植物种群空间分布格局的主要因子是海拔。结果表明：影响天山越高分布越少,而7月平均温度越高分布越广;影响南坡荒漠优势物种空间分布的因子较复杂,但土壤中N含量是其中一个重要因子。影响亚高山草甸优势种群空间分布的因子较多,但比较重要的因子包括土壤CaCO3含量及1月平均温度为负面因子,而降水量是比较重要的正影响因子;影响高山草甸优势种群空间分布的主要因子虽然很多,但是降水量、1月平均温度和7月平均温度等是主要影响因子。     

青藏高原高寒草甸物种多样性的海拔梯度分布格局及对地上生物量的影响

植物物种多样性在海拔梯度上的变化规律以及物种多样性与生产力的关系是生态学研究的热点, 至今还没有得出一般性规律。本文以青海省海南藏族自治州贵德县的拉脊山(36°21′ N, 101°27′ E, 海拔3,389-3,876 m)和果洛藏族自治州的玛沁县军牧场山体(34°22′ N, 100°30′ E, 海拔4,121-4,268 m)为研究对象, 对植物高度、盖度、地上生物量和物种多样性随海拔高度的变化进行调查和统计分析, 以探讨青藏高原高寒草甸的物种多样性和地上生物量在海拔梯度上的变化规律及两者的关系。结果表明: (1)两条山体样带上地上生物量与物种多样性随海拔的变化规律一致: 随着海拔的升高, 地上生物量线性降低; Shannon-Wiener指数、Simpson指数和物种丰富度都呈单峰曲线, 在中间海拔最大, 而Pielou指数随海拔的升高线性增加。结合目前针对青藏高原高寒草甸的研究数据, 发现物种丰富度随海拔高度的变化均呈单峰曲线, 说明随着海拔的升高物种多样性先升高后降低可能是青藏高原物种多样性分布的普遍规律。(2)地上生物量与物种多样性的关系在两条山体样带上表现一致: 地上生物量随Shannon- Wiener指数、Simpson指数和Pielou指数的升高而线性降低, 但与物种丰富度不相关。综合两条山体样带所有样方数据, 发现地上生物量与Shannon-Wiener指数、Simpson指数不相关, 而随物种丰富度的升高线性增加。结合目前在青藏高原的相关研究数据, 发现地上生物量与物种丰富度呈S型曲线(logistic model)。     

Leaf area index and net primary productivity along subtropical to alpine gradients in the Tibetan Plateau

Aim Our aims were to quantify climatic and soil controls on net primary productivity (NPP) and leaf area index (LAI) along subtropical to alpine gradients where the vegetation remains relatively undisturbed, and investigate whether NPP and LAI converge towards threshold‐like logistic patterns associated with climatic and soil variables that would help us to verify and parameterize process models for predicting future ecosystem behaviour under global environmental change. Location Field data were collected from 22 sites along the Tibetan Alpine Vegetation Transects (TAVT) during 1999–2000. The TAVT included the altitudinal transect on the eastern slope of the Gongga Mountains in the Eastern Tibetan Plateau, with altitudes from 1900 m to 3700 m, and the longitudinal‐latitudinal transect in the Central Tibetan Plateau, of approximately 1000 km length and 40 km width. Methods LAI was measured as the product of foliage biomass multiplied by the ratio of specific leaf area. NPP in forests and shrub communities was estimated as the sum of increases in standing crops of live vegetation using recent stem growth rate and leaf lifespan. NPP in grasslands was estimated from the above‐ground maximum live biomass. We measured the soil organic carbon (C) and total and available nitrogen (N) contents and their pool sizes by conventional methods. Mean temperatures for the year, January and July and annual precipitation were estimated from available meteorological stations by interpolation or simulation. The threshold‐like logistic function was used to model the relationships of LAI and NPP with climatic and soil variables. Results Geographically, NPP and LAI both significantly decreased with increasing latitude (P < 0.02), but increased with increasing longitude (P < 0.01). Altitudinal trends in NPP and LAI showed different patterns. NPP generally decreased with increasing altitude in a linear relationship (r² = 0.73, P < 0.001), whereas LAI showed a negative quadratic relationship with altitude (r² = 0.58, P < 0.001). Temperature and precipitation, singly or in combination, explained 60–68% of the NPP variation with logistic relationships, while the soil organic C and total N variables explained only 21–46% of the variation with simple linear regressions of log‐transformed data. LAI showed significant logistic relationships with both climatic and soil variables, but the data from alpine spruce‐fir sites diverged greatly from the modelled patterns associated with temperature and precipitation. Soil organic C storage had the strongest correlation with LAI (r² = 0.68, P < 0.001). Main conclusions In response to climatic gradients along the TAVT, LAI and NPP across diverse vegetation types converged towards threshold‐like logistic patterns consistent with the general distribution patterns of live biomass both above‐ground and below‐ground found in our earlier studies. Our analysis further revealed that climatic factors strongly limited the NPP variations along the TAVT because the precipitation gradient characterized not only the vegetation distribution but also the soil N conditions of the natural ecosystems. LAI generally increased with increasing precipitation and was well correlated with soil organic C and total N variables. The interaction between LAI growth and soil N availability would appear to have important implications for ecosystem structure and function of alpine spruce‐fir forests. Convergence towards logistic patterns in dry matter production of plants in the TAVT suggests that alpine plant growth would increase in a nonlinear response to global warming.     

Altitudinal patterns of plant species richness on the Baekdudaegan Mountains, South Korea: mid-domain effect, area, climate, and Rapoport’s rule

We studied the altitudinal patterns of plant species richness and examined the effects of geometric constraints, area, and climatic factors on the observed richness patterns along the ridge of the Baekdudaegan Mountains, South Korea. Rapoport’s altitudinal rule was evaluated by examining the relationship between altitudinal range size and midpoint. We also examined the latitudinal effect on species richness. Plant data were collected from 1,100 plots along a 200–1,900 m altitudinal gradient along the ridge of the Baekdudaegan. A total of 802 plant species from 97 families and 342 genera were found. The altitudinal patterns of plant species richness along the ridge of the Baekdudaegan depicted distinctly hump-shaped patterns, although the absolute altitudes of the richness peaks vary somewhat among plant groups. While the mid-domain effect (MDE) was the most powerful explanatory variable in simple regression models, species richness was also associated with climatic factors, especially mean annual precipitation (MAP) and temperature (MAT) in multiple regression models. The relative importance of the MDE and climatic factors were different among plant groups. The MDE was more important for woody plants and for large-ranged species, whereas climatic factors were better predictors for total and herbaceous plants and for small-ranged species. Rapoport’s altitudinal rule and a latitudinal effect on species richness were not supported. Our study suggests that a combined interaction of the MDE and climatic factors influences species richness patterns along the altitudinal gradient of the Baekdudaegan Mountains, South Korea.     

华北地区落叶松林的分布、群落结构和物种多样性

华北落叶松(Larix principis-rupprechtii)林、日本落叶松(L. kaempferi)林及太白红杉(L. chinensis)林是华北地区常见的3种落叶松林类型, 其中日本落叶松林为人工林, 华北落叶松林既有天然分布又有人工种植, 太白红杉林则主要是天然林。该研究基于野外调查数据, 对这3种落叶松林的分布、物种组成、群落结构、物种多样性及其与环境间的关系进行了分析。研究发现, 3种落叶松林的分布受年平均气温的影响较大, 随着年平均气温的增加, 落叶松林的天然分布减少而人工种植的分布增加。3种森林中落叶松的林分径级及树高均为右偏分布, 说明3种落叶松林均处于相对稳定的演替阶段。3种落叶松林均拥有较高的物种丰富度且差异显著, 其中太白红杉林的物种丰富度最大(39.3 ± 17.9), 而华北落叶松林的物种丰富度最小(人工林27.2 ± 17.7, 天然林27.5 ± 13.8)。除最大树高与经度的关系不显著以外, 落叶松林的最大胸径和最大树高及物种丰富度均随经纬度的增加而显著降低, 随着年降水量的增加而显著增加。此外, 年平均气温对落叶松林的总物种丰富度影响不大, 但是对其群落结构影响显著。随着年平均气温的升高, 落叶松林的最大胸径显著降低而最大树高却显著增加。落叶松天然林和落叶松人工林物种多样性的地理分布格局及与气候因子间的关系与落叶松林总体的基本一致, 但群落结构的格局不尽相同: 随着经纬度的增加, 落叶松人工林的最大树高增加而天然林的最大树高减小; 落叶松天然林的最大胸径和最大树高分别随年平均气温的升高和年降水量的增加而减小, 而落叶松人工林的最大胸径和最大树高分别随年平均气温的升高和年降水量的增加而增大。     

Climatic controls of vegetation vigor in four contrasting forest types of India—evaluation from National Oceanic and Atmospheric Administration’s Advanced Very High Resolution Radiometer datasets (1990–2000)

Ten-day advanced very high resolution radiometer images from 1990 to 2000 were used to examine spatial patterns in the normalized difference vegetation index (NDVI) and their relationships with climatic variables for four contrasting forest types in India. The NDVI signal has been extracted from homogeneous vegetation patches and has been found to be distinct for deciduous and evergreen forest types, although the mixed-deciduous signal was close to the deciduous ones. To examine the decadal response of the satellite-measured vegetation phenology to climate variability, seven different NDVI metrics were calculated using the 11-year NDVI data. Results suggested strong spatial variability in forest NDVI metrics. Among the forest types studied, wet evergreen forests of north-east India had highest mean NDVI (0.692) followed by evergreen forests of the Western Ghats (0.529), mixed deciduous forests (0.519) and finally dry deciduous forests (0.421). The sum of NDVI (SNDVI) and the time-integrated NDVI followed a similar pattern, although the values for mixed deciduous forests were closer to those for evergreen forests of the Western Ghats. Dry deciduous forests had higher values of inter-annual range (RNDVI) and low mean NDVI, also coinciding with a high SD and thus a high coefficient of variation (CV) in NDVI (CVNDVI). SNDVI has been found to be high for wet evergreen forests of north-east India, followed by evergreen forests of the Western Ghats, mixed deciduous forests and dry deciduous forests. Further, the maximum NDVI values of wet evergreen forests of north-east India (0.624) coincided with relatively high annual total precipitation (2,238.9 mm). The time lags had a strong influence in the correlation coefficients between annual total rainfall and NDVI. The correlation coefficients were found to be comparatively high (R²=0.635) for dry deciduous forests than for evergreen forests and mixed deciduous forests, when the precipitation data with a lag of 30 days was correlated against NDVI. Using multiple regression approach models were developed for individual forest types using 16 different climatic indices. A high proportion of the temporal variance (>90%) has been accounted for by three of the precipitation parameters (maximum precipitation, precipitation of the wettest quarter and driest quarter) and two of the temperature parameters (annual mean temperature and temperature of the coldest quarter) for mixed deciduous forests. Similarly, in the case of deciduous forests, four precipitation parameters and three temperature parameters explained nearly 83.6% of the variance. These results suggest differences in the relationship between NDVI and climatic variables based upon the time of growing season, time interval and climatic indices over which they were summed. These results have implications for forest cover mapping and monitoring in tropical regions of India.     

Leaf life span as a simple predictor of evergreen forest zonation in China

Aim Our aim was to investigate how the average life span of canopy leaves might be used to predict the geographical distribution of natural forests at large geographical scales, and to explore the link between leaf characteristics and ecosystem functioning. We examine whether there is a general relationship between canopy mean leaf life span and climate (i.e. temperature and precipitation) that can be used to predict evergreen forest zonation in China. Location Forest areas in China. Methods During July and August of 2002–2004, we conducted a latitudinal forest transect spanning about 30° of latitude in eastern China. The canopy mean leaf life span was calculated to include all tree species (groups) in each forest plot through weighted averages scaled up from branch‐level measurements. Data from our previous work conducted in the Tibetan Alpine Vegetation Transects (TAVT) and from other investigators were compiled to supplement our results. Based on regression equations developed on the pooled data, and using gridded temperature and precipitation datasets, we simulated the distribution of canopy mean leaf life span for forests in China. The predicted leaf life span zonation was compared with a map of Chinese forest vegetation divisions published in 1980. Results Canopy mean leaf life span across 10 evergreen forest plots in eastern China showed a decreasing trend as mean annual temperature increased, following a common logistic pattern consistent with the data from the TAVT and other investigators. In pooled data for 40 evergreen forest plots across tropical and boreal regions, canopy mean leaf life span generally showed a negative relationship with mean annual temperature (r² = 0.72, P < 0.001), and a positive correlation with mean annual precipitation where mean annual temperature was > 8°C (r² = 0.45, P < 0.01). The climate‐based simulations of leaf life span zonation compared well with the previously published boundaries of forest vegetation divisions in eastern China. Main conclusions Our results reveal that mean leaf life span in evergreen forests follows a common logistic pattern associated with mean annual temperature and precipitation, which can in turn be used to predict evergreen forest zonation in eastern China.     

内蒙古昆虫物种多样性分布格局及其机制

物种多样性的地理分布格局及其机制是宏生态学和生物地理学的核心问题之一。区域尺度与局域尺度的影响因素, 如温度、降水、海拔变化、生境过滤、捕食、竞争与互惠等, 共同影响昆虫物种多样性的分布格局。然而, 迄今为止少有研究同时讨论不同尺度驱动因子对昆虫多样性地理分布格局的影响。本文基于内蒙古自治区86个旗县的昆虫多样性数据, 结合各地年平均气温、年降水量、古气候变化、海拔变化及植物多样性, 探讨昆虫物种多样性分布格局及其主要驱动因子。结果发现内蒙古昆虫多样性主要受到植物多样性与海拔变化的影响, 而气候因子对昆虫物种多样性的影响并不大。这一结果表明种间关系(食物多样性)与生境异质性可能对内蒙古昆虫多样性的分布格局起着主导作用。     

黄土高原不同植被覆被类型NDVI对气候变化的响应

植被与气候是目前研究生态与环境的重要内容。为探究黄土高原地区植被与气候因子之间的响应机制,利用线性趋势分析、Pearson相关分析、多元线性回归模型以及通径分析的方法,对黄土高原2000—2015年全区和不同植被覆被类型区内NDVI与气候因子的变化趋势以及相互作用关系进行分析。植被覆被分类数据和植被指数数据分别来源于ESA CCI-LC(The European Space Agency Climate Change Initiative Land Cover)以及MODND1T/NDVI(Normalized Difference Vegetation Index)。结果表明:(1) 2000—2015年黄土高原全区植被年NDVI_(max)显著增加的区域占总面积的74.25%,不同植被覆被类型年NDVI_(max)分别为常绿阔叶林常绿针叶林落叶阔叶林落叶针叶林镶嵌草地农田镶嵌林地草地灌木,并且都呈显著增加趋势,其中常绿阔叶林和农田增加幅度最大,为0.012/a。(2)黄土高原全区NDVI与气温、日照、降水和相对湿度等气候因子之间没有显著相关性,但在不同植被覆被类型区,气候因子对NDVI存在显著作用,且不同植被覆被类型差异明显。(3)在全区和不同植被覆被类型区NDVI仅对降水的响应比较一致,气温无论在整个区域尺度还是不同植被覆被类型区对植被的影响均不显著。(4)常绿阔叶林、落叶阔叶林、常绿针叶林及镶嵌林地等以乔木为主的植被覆被类型受年均相对湿度和年总日照时数的显著负效应驱动,草地、镶嵌草地等以草本为主的植被覆被类型则受到年总降水量的显著正效应影响。这说明对植被类型进行区分,更有利于揭示气候对植被的作用机制。     

Patterns and controls of the variability of radiation use efficiency and primary productivity across terrestrial ecosystems

Aim The controls of gross radiation use efficiency (RUE), the ratio between gross primary productivity (GPP) and the radiation intercepted by terrestrial vegetation, and its spatial and temporal variation are not yet fully understood. Our objectives were to analyse and synthesize the spatial variability of GPP and the spatial and temporal variability of RUE and its climatic controls for a wide range of vegetation types. Location A global range of sites from tundra to rain forest. Methods We analysed a global dataset on photosynthetic uptake and climatic variables from 35 eddy covariance (EC) flux sites spanning between 100 and 2200 mm mean annual rainfall and between ?13 and 26°C mean annual temperature. RUE was calculated from the data provided by EC flux sites and remote sensing (MODIS). Results Rainfall and actual evapotranspiration (AET) positively influenced the spatial variation of annual GPP, whereas temperature only influenced the GPP of forests. Annual and maximum RUE were also positively controlled primarily by annual rainfall. The main control parameters of the growth season variation of gross RUE varied for each ecosystem type. Overall, the ratio between actual and potential evapotranspiration and a surrogate for the energy balance explained a greater proportion of the seasonal variation of RUE than the vapour pressure deficit (VPD), AET and precipitation. Temperature was important for determining the intra‐annual variability of the RUE at the coldest energy‐limited sites. Main conclusions Our analysis supports the idea that the annual functioning of vegetation that is adapted to its local environment is more constrained by water availability than by temperature. The spatial variability of annual and maximum RUE can be largely explained by annual precipitation, more than by vegetation type. The intra‐annual variation of RUE was mainly linked to the energy balance and water availability along the climatic gradient. Furthermore, we showed that intra‐annual variation of gross RUE is only weakly influenced by VPD and temperature, contrary to what is frequently assumed. Our results provide a better understanding of the spatial and temporal controls of the RUE and thus could lead to a better estimation of ecosystem carbon fixation and better modelling.     

中国云杉林的地理分布与气候因子间的关系

为了揭示中国云杉林的地理分布与气候因子间的关系, 在中国云杉林15个群系的地理分布范围内选取613个地理坐标点, 其中包括云杉各个种分布的海拔上限和下限坐标点各235和228个。通过数字地球系统确定每个点的海拔高程, 从中国气象插值数据库获取每个点的气候数据。数据分析分别采用线性回归、变异系数比较和主成分分析(PCA)法。结果显示, 中国云杉林分布范围内, 年平均气温、最冷月平均气温、最热月平均气温、≥5 ℃积温、≥0 ℃积温、年降水量、土壤水分含量和干燥指数α的平均值分别是3.38 ℃、-9.75 ℃、14.78 ℃、1 227.83 ℃·d、2 271.19 ℃·d、712.23 mm、80.02%和0.50; 各气候因子与中国云杉林垂直分布的上下限间均具有显著的回归关系; 除了年平均气温和最冷月平均气温变异系数较大外, 其他6个气候因子的变异系数均较小, 且彼此间无显著差异; 无论是云杉分布的上限还是下限, ≥5 ℃积温和≥0 ℃积温在PCA第一主分量具有较高的载荷, 而年降水量和土壤水分含量在第二、三主分量具有较高的载荷。影响中国云杉林分布的主要气候因子是生长季节积温, 其次是年降水量和土壤水分含量。     

The role of bioclimatic origin,residence time and habitat context in shaping non-native plant distributions along an altitudinal gradient

An important factor influencing whether or not a non-native plant species becomes invasive is the climate in the area of introduction. To become naturalised in the new range, a species must either be climatically pre-adapted (climate matching), have a high phenotypic plasticity, or be able to adapt genetically, which in the latter case may take many generations. Furthermore, patterns of successful establishment across species might vary with habitat context. To address the interaction of these factors on non-native species richness, we recorded the presence of non-native annual plant species along an altitudinal gradient on Tenerife (Canary Islands, Spain). We compared the distributions of species differing in bioclimatic origin (Mediterranean and temperate) and time since introduction (old and recent introductions), and compared richness patterns of these groups in anthropogenic and natural habitats. Non-native species richness increased strongly from lowlands to mid-altitudes, but dropped sharply at the transition from anthropogenic to natural habitats, and thereafter declined with altitude in the natural habitat. This pattern indicates that the altitude effects reflected changes in both climate and habitat context. Mediterranean and temperate species were distributed similarly along the altitudinal gradient, and we found no effect of bioclimatic origin on species distributions. As almost all species present at the highest sites also occurred in the lowlands, we conclude that most species were introduced to lowland sites and were therefore pre-adapted to those climatic conditions (lowland introduction filter). The altitudinal ranges of species tended to increase with time since introduction, and the species reaching the highest altitudes were mostly old introductions. This effect of time was more pronounced among Mediterranean than temperate species. Thus, while climatic pre-adaptation is important for establishment along this altitudinal gradient, species tend to extend their altitudinal range with time.