1960-2011年陕西省年内降水分配非均匀性特征及预测

根据陕西省19个气象站点1960-2011年逐日降水资料,利用反距离加权插值、气候趋势系数、M-K突变检验、Morlet小波分析、相关分析、合成分析和R/S分析等方法对陕西省年内降水集中度和集中期变化特征及其未来变化趋势进行分析.结果表明:1960-2011年,陕西省年内降水集中度为0.44 ～0.66,总的分布特征是南北高、中部低,而年内降水集中期变化于18.32 ～22.37旬,地域差异较小;年内降水集中度呈增加趋势,而年内降水集中期呈提前趋势,且二者的变化趋势均存在明显的区域差异;年内降水集中度在1974年发生减小突变,而年内降水集中期在1962年发生推后突变;年内降水集中度和集中期的变化并没有一个固定周期,而是大、中、小多种周期尺度相互嵌套,具有较强的时频局部特征;年降水量与年内降水集中度在全省表现出一致的正相关,而与年内降水集中期除在陕北的横山呈微弱的负相关外,在其他地区均呈正相关;多水年与少水年降水集中度的空间分布均呈南北高、中间低的特征,而多水年和少水年的降水集中期空间分布差异较大;年内降水集中度和集中期的未来变化趋势将与过去52年的变化趋势保持一致.     

长白山地区生长季降水不均匀性特征

利用长白山地区13个台站1960-2007年逐日降水资料,采用降水集中度和降水集中期的概念,提出降水集中时段的指标,并应用这些指标分析了该地区生长季降水特征.结果表明:历年降水集中度平均为0.31,年际、年代际变化特征明显;降水集中度准10年周期波动比较明显;从降水集中度的站间差异看,具有明显的空间非均一性;历年降水集...     

降水量季节分配对克氏针茅草原群落初级生产力的影响

本文根据克氏针茅草原群落初级生产力连续１４年的定位观察资料,分析了降水量及其季节分配对群落初级生产力力年度波动的影响,并应用积分回归模型,计算出１－８月各旬降水量对群落初级生产力的影响系数。结果表明：降水量的年度变化及其季节分配直接导致了克氏针茅草原群落初级生产力的年度波支１月上旬至４月上旬６旬至８月下旬的旬降水量对群落初级生产力均具有正效应。是植物对水分需求的两个关键时期。其中,１月上旬至４月上     

辽宁省5-9月降水日变化特征

基于1994-2008年逐年5-9月辽宁省52个气象台站的逐时降水数据,应用逐时降水量、逐时降水频次、逐时降水强度和不同持续时间降水4个指标对辽宁省降水日变化特征进行了研究.结果表明:辽宁省5-9月降水量和降水频次都呈现双峰型的日变化特征,峰值区为14:00-17:00和2:00-8:00;降水强度日变化呈现单峰型,峰值区位于14:00-17:00;各时次降水量与降水强度平均相关系数为0.8,与降水频次相关系数为0.5,降水量变化与降水强度关系密切,受降水频次影响较小;短时降水降水量和频次对总降水量和总降水次数的贡献较长持续时间降水的大,且短时降水多发于14:00-19:00,长持续时间降水主要出现于2:00-9:00.     

川西亚高山暗针叶林降水分配过程中氧稳定同位素特征

该文应用氧稳定同位素对四川卧龙巴朗山不同降雨条件下亚高山暗针叶林中降水、林冠穿透水和壤中流的变化动态进行了示踪,结果表明: 1)降水δ¹⁸O与林冠穿透水δ¹⁸O的差值(用Δ表示)随着日降雨量的增大呈现偏正态结构。降水量<3.20 mm时,Δ<0;当降水量≥3.20 mm时,Δ>0;且当降水量=12.65 mm时,Δ值最大。这是由当时冠层蒸散过程和降水过程相互作用决定的。 2)低降水强度、日平均降水量小和降水连续性差时,壤中流弱且不连续,导致壤中流的氧同位素组成对降水响应速度慢;反之,壤中流强且连续,导致壤中流对降水响应速度加快。当降水量在< 10 mm时,这种响应在降雨后4 d发生;当降水量在10~20 mm时,日平均降水量较大和连续降雨时,这种响应在降雨后2~3 d发生;当降水量在20~30 mm时,这种响应在降水1~2 d发生。发育良好的原始亚高山暗针叶林森林植被对降水分配进行着有效的调控,使得暗针叶林植被储备着不同时期降水、穿透水、壤中流及地下水组成的混合体,使壤中流变化滞后,从而控制植被下游洪水发生。     

黄河中游绿水系数变化及其生态环境意义

绿水和蓝水的概念和理论对于半干旱、半湿润区水资源的评价和管理有重要意义。引入流域尺度上绿水系数指标,定义为某一流域内由降水到绿水的转换系数。研究发现,1950—2011年间,黄河中游河口镇至龙门区间(河龙区间)的绿水系数呈现增大的趋势。除了气温、降水的影响外,水土保持是一个重要因素。水土保持措施减少了降雨到径流(蓝水)的转化率,增大了降雨到绿水的转化率。绿水系数的增大意味着坡面径流减弱和河流径流的减弱,从而减少了坡面侵蚀和流域产沙。同时,绿水系数的增大意味着植被蒸腾作用的增强,说明植被对地表的保护作用增强,这也会导致坡面侵蚀的减弱。河龙区间产沙量与流域绿水系数之间呈显著的负相关关系,产沙量变化的53.7%可以用流域绿水系数的变化来解释。水土保持实施后,梯田和坝地使得生产性绿水系数增大,从而增加了粮食产量。梯田、坝地面积与绿水系数和粮食产量之间都存在着显著的正相关关系,粮食产量与绿水系数之间也存在显著的正相关关系。绿水系数具有流域生态环境质量变化的指示意义,在年降水可比的情况下,流域绿水系数的减小意味着集水区生态环境环境质量降低,流域绿水系数的增大意味着集水区生态环境质量提高。依照绿水系数的变化,可以将近60余年来河龙区间生态环境的变化过程划分为3个阶段。     

内蒙古草原生态系统净初级生产力及其与气候的关系

该文在利用朱文泉等(2007)构建的基于光能利用率的净初级生产力(NPP)遥感估算模型对内蒙古草原生态系统1982-2006年的NPP进行估算的基础上, 选取包括降水量、温度、有效降水、有效温度和3种地表干湿度指数在内的气候指标, 充分考虑地表覆盖状况和气候因子的时滞和累积效应, 探讨了内蒙古草原生态系统NPP与气候因子之间的相互作用关系。结果表明, 以年为时间单位, 在年际水平上, 温度相关的各指标与年NPP的关系并不明显, 当年的气候条件对草原区植被的生长影响最大。以月为时间单位, 年内月气温和降水是影响NPP的重要因素。且所有植被类型区在年内月际水平上气候各指标对NPP的影响时效最大为1个月, NPP和各气候参量的关系时效也为1个月; 在年际水平上5-9月的NPP与降水、地表干湿度指数的互相关系数明显高于同温度各指标的互相关系数, 表明降水是影响内蒙古草原NPP的主要气候因子, 且降水的累积效应影响显著。不同植被类型区年际月NPP与降水指标之间的关系也各不相同。     

黄土高原降水年内分布差异对旱作果园蒸散特征的影响

天然降水是雨养农业区水文循环的主要驱动因子,在一定程度上决定着土壤水分生态环境,从而影响作物的蒸散特征。本研究通过分析静宁地区历年降水年内分布特征,明确了降水的集中趋势,在2018和2019年田间定位试验基础上,探究土壤水分随降水发生的变化过程以及果园蒸散特征对降水年内分布差异的响应规律。结果表明: 试验区历年降水集中度较高,集中期多分布在7和8月,8月所占比例达75%,且各年降水集中期出现的早晚变化较大。土壤水分对降水的响应主要集中在0～40 cm土层,深层水分只有在大雨量和连续性降水出现时才会发生明显变化。同为丰水年的情况下,2018年降水集中度高,集中期早,时间短,果树日耗水强度呈单峰结构,变幅较大;2019年降水分布均匀,集中期滞后,日耗水强度呈双峰结构,变幅小,大峰靠后。果树最大需水期历时长,2018年大雨的集中分布无法满足后期果树生理需水,果实产量受损,降水利用效率较2019年下降30.2%。黄土高原地区在苹果树幼果生长期往往会出现短暂干旱,影响果实品质,需加强该时段的水分管控。     

漓江上游典型森林植被对降水径流的调节作用

利用野外同步长期定位观测林外降雨、地表径流和河川径流的方法,对漓江上游典型森林植被的生态水文过程进行观测研究。结果表明:1)流域降水年内分配极不均匀,50a年降雨量总体变化趋势不明显。林冠截留受林外降雨特征的影响,也与植被类型密切相关。2)地表径流平均滞后时间为70 min。在连续降雨的情况下,降雨滞后效应不再明显,甚至出现地表径流与降雨同步的现象,小降雨可能产生大的地表径流,从而加大流域在雨季发生洪灾的风险。3)湿季径流系数略大于旱季,干季降水量减少,且森林植被消耗大量水分,减少了枯水期径流的产生,增大发生旱灾的风险。森林植被延长河川径流持续时间,使一次持续18 d的降水过程形成的径流,在降水停止后能延续24 d。降雨后退水持续时间与前期降水及后期降水叠加有关。目的为揭示漓江上游森林植被对降水径流的调节作用,客观评估漓江上游水资源潜力、加强流域水资源管理和森林经营提供科学依据。     

多卫星降水产品在环渤海地区的精度评价

降水是全球能量和水循环中的重要变量之一,降水资料的精度对洪旱灾害的监测与预报、水资源管理等至关重要.本文利用环渤海地区1998—2014年55个气象站点的逐日降水数据,分别从日、月尺度对TRMM 3B42、CMORPH、PERSIANN 3种卫星降水产品进行精度评价,并对其季节差异进行分析.结果表明: 总体上,TRMM 3B42 V7的精度最高,PERSIANN精度最低,但CMORPH对日降水事件的探测成功率(0.69)最高;3B42略高估算了日降水量,其他两者则对日降水量存在低估.春、夏、秋季各卫星降水产品对降水的成功探测率高于冬季,且相关系数、均方根误差等指标随季节变化明显.3种卫星降水产品的月尺度估算精度优于日尺度,其中对日降水量的估算精度较低,特别是明显低估了暴雨事件的实际降水量.本研究为卫星降水产品在环渤海地区降水估算及其在气候与水文模拟和预测中的应用提供了依据和支持.     

Spatio-temporal variation in vegetation net primary productivity and its relationship with climatic factors in the Shule River basin from 2001 to 2010

The study area incorporated the Shule River basin, located in northwest Gansu Province, an important water source and ecological division within the Hexi Corridor. We calculated NPP using MODIS images, meteorological data, vegetation type maps, and the improved CASA NPP model. We analyzed NPP spatio-temporal characteristics in the study area for 2001–2010 using linear trend analysis, coefficient of variation, and the Hurst index. The following general outcomes were found: NPP in the study area showed considerable regional differences. NPP gradually decreased from southeast to northwest, with significant linear longitudinal patterns. Inter-annual variability showed overall growth over the study period. Significant NPP increase occurred for 25.15% of the total study area, whereas 11.93% showed significant decrease. The Hurst index indicated that the majority of NPP changes followed the same trend, with 78.3% of the study area expected to continuously increase, and 21.7% expected to decrease in the future. There was a weak relationship between NPP and annual precipitation, but no significant relationship between NPP and annual average temperature, indicating that precipitation was the key annual influence. Temperature was the dominant climatic factor affecting NPP on a monthly scale, and precipitation and temperature annual correlations were lower than those for the monthly scale.     

芦芽山阳坡不同海拔华北落叶松径向生长对气候变化的响应

为研究树木生长对气候变化的响应状况,选取芦芽山阳坡的3个海拔高度建立了华北落叶松(Larix principis-rupprechtii)的树轮宽度年表。年表的统计参数表明,3条年表均为研究气候信息的可靠资料。结果表明,芦芽山阳坡华北落叶松的径向生长和生长与气候的关系均具有海拔差异,中海拔(2440 m)和高海拔(2540 m)的华北落叶松具有相似年际生长变化,而二者均与低海拔(2330 m)华北落叶松的年际生长不同。低海拔华北落叶松的生长与4月平均气温和上一年11月降水量显著负相关,而中海拔和高海拔的生长均与上一年10月平均气温和6月降水量显著负相关。通过年表与气候因子之间的滑动相关分析发现,3个海拔高度华北落叶松生长与气候因子的关系均不稳定,生长与气温条件之间的显著相关关系是随着气温升高而出现的。气温的升高引起了华北落叶松生长与气温因子关系的海拔差异,以及径向生长的海拔差异。这一结果对于气候变化对植被垂直梯度影响的研究具有一定参考价值。     

Climate as a determinant of dung beetle response to native forest replacement by cattle pastures in South America

Anthropogenic disturbance in natural ecosystems reduces the number of species in biological communities and homogenizes their composition across different regions. Climate is one of the main abiotic determinants of species distributions and different factors were proposed as the main climatic drivers. Here we explored the role of regional climate on the local response of dung beetle assemblages to the replacement of native forest by cattle pastures in South America by simultaneously contrasting three climatic hypotheses: energy, seasonality and heterogeneity. We compiled a database by searching published studies comparing dung beetle richness and composition between both native forests and cattle pastures. We calculated the proportional difference in species richness and composition between habitat types. As explanatory variables, we used seven abiotic variables grouped into the three climatic hypotheses. Energy/Productivity: mean annual temperature (°C/year) and total annual precipitation (mm/year). Seasonality: annual thermal amplitude (°C/year), the average coefficient of variation of monthly precipitation and the coefficient of average monthly variation in temperature. Heterogeneity: coefficient of variation of mean annual temperature, coefficient of variation of mean annual precipitation. Using regression analyses and a model selection procedure, we found differences in species richness between native forests and cattle pastures were explained by the coefficient of variation of mean annual precipitation, whereas changes in species composition were explained by total annual precipitation and the coefficient of variation of mean annual precipitation. The response of dung beetle assemblages to livestock grazing in South American forests was associated with precipitation variation. The heterogeneity hypothesis better explained changes in species richness following forest replacement by cattle pastures, while both energy/productivity and heterogeneity hypotheses explained the changes in species composition.     

六盘山地区油松树轮宽度年表与多尺度标准化降水指数的关系

研究利用在六盘山地区采集的油松树轮样芯建立树轮宽度标准年表(STD),分别与不同长度时间单元(月、半月、旬)和多时间尺度的标准化降水指数(SPIn)序列进行相关性分析。油松标准年表与不同长度时间单元SPI的相关结果显示,较小的时间单元会使相关性表达更加精确,而时间单元过小则会因为数据波动性增大而导致相关关系弱化。因此,相较于月和旬,半月是相关性分析更为合适的时间单元长度。油松标准年表与多时间尺度SPI的相关结果显示,SPI多时间尺度的特性有助于揭示油松径向生长对不同时间尺度水分状况的响应特征,且油松在不同生长时期对于不同时间尺度水分状况具有相异的响应机制。在温度较低(0℃)的冬季,短时间内的降水并不利于树木生长,而长时间良好的水分储备会为树木生长季需水提供保障;在生长季前期,长时间良好的水分状况比短期内的降水更有利于树木的生长;在生长季,补给性水分和土壤水分都对树木生长起着至关重要的作用。     

千山油松年轮宽度年表的建立及其与气候的关系

以千山油松为样本,建立了年轮宽度标准化年表、差值年表和自回归年表.结果表明,油松年轮宽度与5—7和9—11月温度指标的相关性较高,且与低温呈正相关,其中与7月的极端最低温、9月的平均最低温显著相关.3种年表与上年12月和当年1月的极端最低温、1月的平均最低温呈显著相关,且其与全年、上年12月、当年5月的降水量显著相关,与4月的降水量极显著相关.油松与水汽压、相对湿度的月和年指标均有较强的相关性.蒸发的年指标和绝大部分月指标对油松生长具有负效应,其中4—7月最明显.油松年表的窄化突变佐证了1800年以来的30次主要的旱灾年历史记录.千山油松的生长受全球或半球尺度气候变化的影响.年表与太阳活动存在显著的11、23和50年左右的公共周期,与地磁指标在10、20和45年左右存在共同的周期变化.     

Multi-scale comparison of topographic complexity indices in relation to plant species richness

Topographic complexity is a key component of habitat, which has been linked to increased species richness in many ecological communities. It can be measured in various ways and it is unclear whether these different measurements are mutually comparable when they relate to plant species richness at different spatial scales. Using a densely sampled set of observations for Rhododendrons (406 species and 13,126 georeferenced records) as a test case, we calculated eight topographic complexity indices from a 250-m resolution digital elevation model and examined their correlations with Rhododendron species richness in China at seven spatial scales: grain sizes 0.05°, 0.1°, 0.25°, 0.5°, 1.0°, 1.5°, and 2.0°. Our results showed that the eight topographic complexity indices were moderately to highly correlated with each other, and the relations between each pair of indices decreased with increasing grain size. However, with an increase in grain size, there was a higher correlation between topographic complexity indices and Rhododendron species richness. At finer scales (i.e. grain size ≤ 1°), the standard deviation of elevation and range of elevation had significantly stronger correlations with Rhododendron species richness than other topographic complexity indices. Our findings indicate that different topographic complexity indices may have positive correlations with plant species richness. Moreover, the topographic complexity–species richness associations could be scale-dependent. In our case, the correlations between topographic complexity and Rhododendron species richness tended to be stronger at coarse-grained macro-habitat scales. We therefore suggest that topographic complexity index may serve as good proxy for studying the pattern of plant species richness at continental to global levels. However, choosing among topographic complexity indices must be undertaken with caution because these indices respond differently to grain sizes.     

拉格朗日逆分析在森林蒸散模拟中的应用

以长白山阔叶红松林为研究对象,根据Raupach提出的LocalizedNearField(LNF)理论为依据,耦合垂直速度标准差σ_w(z)和拉格朗日时间尺度T_L(z),建立林冠内水汽源汇强度和平均浓度廓线之间的关系;利用拉格朗日逆分析法(inverseLagrangiandispersionanalysis,IL)提出了通过林冠水汽浓度梯度计算林冠内的水汽源汇强度进而推算森林蒸散的方法.最终得到的结果与开路涡动相关系统的观测数据比较显示,对于白天水汽累积通量的模拟精度达到87.3%;IL模拟值高于EC实测值,大约高出15%～25%;林冠白天水汽通量远大于夜间,占日水汽总通量的70%以上.6～8月的水汽白天累积总通量高于5月和9月.     

Spatio‐temporal analysis of the relationship between landscape structure and the olive fruit fly Bactrocera oleae (Diptera: Tephritidae)

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Global patterns in fruiting seasons

Aim   To identify geographical and climatic correlates of the timing of fruit production in fleshy fruited plant communities.
Location   Global.
Methods   We searched the literature for studies documenting monthly variation in the number of fleshy fruited species bearing ripe fruits in plant communities (i.e. fruit phenologies). From these data, we used circular vector algebra to characterize seasonal peaks in fruit production (mean date, as an angle) and the length of fruiting seasons (as a circular standard deviation). Generalized linear models and circular correlations were used to assess whether latitudinal patterns in fruit phenologies could be explained by variation in temperature, precipitation and actual evapotranspiration (AET).
Results   Dates of peak fruit production and the length of fruiting seasons showed consistent differences with latitude. Annual peaks in fruit production occurred 1 to 3 months after the summer solstice at high-latitude sites in both hemispheres. Fruiting seasonality increased with latitude, indicating that fruiting seasons were longer in the tropics and shorter toward the poles. AET was the best climatic predictor of fruit phenologies. Annual peaks in fruit production were positively associated with annual peaks in AET and temperature, while fruiting seasons were shorter in areas with pronounced annual variation in AET.
Main conclusions   Global patterns in fruiting seasons are associated with global variation in climate. Across the globe, fleshy fruits are produced after annual periods of elevated water–energy availability. Fruiting seasonality is also more pronounced in areas with strongly seasonal water–energy inputs. Therefore, the timing of reproduction in fleshy fruited plant communities appears to be determined, at least in part, by spatial and temporal variation in energy supplies needed to subsidise plant reproduction.     

云南省植被NDVI时间变化特征及其对干旱的响应

基于云南省74个气象站点的1997—2012年逐日降水资料和逐旬SPOT-NDVI值,利用标准化降水蒸散指数(SPEI)多尺度分析了云南省干旱时间和强度演变与NDVI时间动态特征及其相关性分析,进而探讨气候变化对植被的影响。结果表明,1999—2013年云南省年平均NDVI值和年最大NDVI值均呈现波浪式的发展趋势,其趋势线斜率分别为0.0017和0.0011;NDVI年内各月变化情况大体上相同;不同季节NDVI的年际变化特征呈现出显著差异。1997—2012年不同时间尺度SPEI均体现出干旱化加剧的趋势,并随SPEI的时间尺度增大而增大;3个月尺度的SPEI值(SPEI3)结果表明,各月的变化呈现先增大后减小的趋势;SPEI3反映出多年季节水平的干旱强度为:冬季秋季春季夏季。总体上,云南省的年均NDVI与SPEI的相关性极弱,年最大NDVI与SPEI呈正相关;多年月均NDVI与不同尺度SPEI的相关性较强且存在滞后性;不同季节NDVI与SPEI的相关性及滞后性有较大差异,其中冬季NDVI、秋季NDVI与其当年当季SPEI的负相关性较强。