山东地区木本植物春季物候对气候变化的响应

利用山东省境内10个国家级农业气象观测站1981-2009年逐年春季物候序列和同期逐日气象资料,通过一元线性回归、相关分析和突变检验方法,分析了山东地区木本植物春季物候期的趋势变化特征及物候期对气候变化的响应关系。结果表明：（1）1980-2009年山东地区春季气温明显升高,春季水汽压呈增大趋势;（2）山东地区近29a的木本植物春季物候期普遍提前,提前的线性倾向率为0.13～1.11d.a-1;（3）山东地区木本植物春季物候期与其前期活动积温、春季气温和3月份水汽压呈负相关关系,物候前期的活动积温是诱发春季物候现象的重要因子,春季气温升高和3月份水汽压增大是近29a春季物候现象提前的可能原因。     

内蒙古小叶杨近30年物候变化特征及其对气温变化的响应

根据近30a内蒙古自治区24个气象站小叶杨的物候观测资料,分析小叶杨春季萌动和秋季叶变色的物候特征,以更好地掌握农时变化,合理安排农牧业生产。结果表明,近30a来,小叶杨春季平均芽开放期有提前的趋势,全区平均提前速率为1.4d/10a,其中20世纪90年代出现提前的年次百分比最高,2000-2008年次之;秋季叶全变色期有推迟的趋势,全区平均推迟速率为3.0d/10a,其中2000-2008年出现推迟的年次百分比最高;小叶杨春季芽开放期与春季气温间存在显著的负相关关系（P〈0.05）,秋季叶全变色期与秋季气温间呈显著的正相关关系（P〈0.05）,即春季气温越高小叶杨芽开放越早,而秋季气温越高小叶杨叶全变色越迟。     

气候变暖对山西南部典型植物物候的影响

选取山西省运城市、临汾市、晋城市和长治县农业气象试验站典型木本和草本植物1982-2004年物候观测资料及各地1970-2004年气温资料,运用距平、线性趋势等方法分析各地气温和植物物候期的变化特征,以及气温对植物物候期的影响。结果表明,(1)春季物候期普遍呈提前趋势,生长季呈延长趋势;木本植物秋季物候期呈推迟趋势,大部分地区草本植物黄枯始期表现为略提前趋势,黄枯末期表现为推迟趋势。(2)随着年平均气温的不断升高,植物春季物候期呈提前趋势;木本植物秋季物候期呈推迟趋势,草本植物黄枯末期大多呈提前趋势。气温每升高1℃,植物展叶始期提前1～18d。     

阿拉善荒漠两种典型豆科植物主要物候期对气候变化的响应

基于近40a阿拉善荒漠监测点气候要素和植被物候观测资料,采用线性倾向率、逐步回归等方法,分析该地区1981−2019年气候变化特征以及短脚锦鸡儿、猫头刺两种豆科植物主要物候期时间的演化趋势,探讨阿拉善荒漠豆科植物物候变化的气候驱动因子,旨在为气候变化背景下典型荒漠地区植物物候研究提供科学依据。结果表明：（1）近40a监测点平均气温为8.8℃,并以0.46℃10a−1的趋势显著上升（P＜0.01）;年日照时数平均为3136h,以约98h10a−1的速率显著减少（P＜0.01）;年降水量平均为159.0mm,呈波动增加趋势,降水量变化倾向率为19.08mm10a−1（P＜0.05）;（2）研究区短脚锦鸡儿、猫头刺的返青期、开花期明显提前,黄枯期略有推后,整个生长季呈延长趋势;短脚锦鸡儿、猫头刺多年平均返青期日序分别为898、9010,开花期日序为11610、13116,黄枯期日序为30810、31510;（3）植被物候期与气候因子的相关分析发现,短脚锦鸡儿和猫头刺物候期变化主要受到气温的限制,日照时数对两种植物的返青期略有影响,降水量仅对短脚锦鸡儿黄枯期有一定影响。     

华南主产区双季水稻物候变化及其与气候条件的关系

为探索华南水稻生长发育对气候变化的敏感性，估算气候变化、品种更替对水稻物候期变化的贡献，选取1981-2013年华南双季水稻种植区物候和气象观测数据，采用Theil-Sen估计线性倾向率、Mann-Kendall趋势显著性检验等方法，分析双季水稻物候期的时空变化趋势。结果表明：与其它地区不同，华南早稻播种期提前、晚稻成熟期推迟趋势较小；早稻、晚稻营养生长期存在缩短趋势，而生殖生长期存在延长趋势。早稻、晚稻的营养生长期、生殖生长期均随着降水量和日照时数的增加而延长，随着气温上升而缩短；平均气温每上升1℃，生长期长度缩短0.5～4.7d。气候变化与品种对水稻物候期影响的贡献率分析表明，品种更替对早稻和晚稻生长期长度的影响大于气候变化。研究期内品种更替中，早稻倾向于选择营养生长期和生殖生长期均长的品种；晚稻倾向于选择营养生长期短、生殖生长期长的品种。     

江西气温稳定通过10℃初日变化及其对双季早稻物候期的影响

利用江西82个气象站1959-2009年日平均气温和14个农业气象观测站1981-2008年的双季早稻物候期资料,分析了气温稳定通过10℃初日的变化及其对双季早稻物候期的影响。结果表明,10℃初日在51a间年际变化十分明显,极差达36d;年代际变化在20世纪80、90年代最为剧烈,2000-2009年次之,60、70年代较为稳定;整个分析期内线性变化趋势不明显,但1991-2009年呈明显提前的趋势。51a间全省10℃初日的区域分布变化明显,3月20日、3月10日分界线从20世纪60-90年代逐步南压,2000年以来大幅度北收;赣南变化幅度大于赣北赣中。10℃初日与双季早稻营养生长期物候期呈正相关,与生殖生长期物候期相关性不明显。典型早年与典型迟年比,双季早稻营养生长期的物候期普遍提前,全省平均提前3.7~9.1d;而在生殖生长期,部分站的物候期转为推迟,总体上早迟年物候期差异在±4d以内;全生育期平均延长3.0d。研究结果可为当地水稻生产布局调整和农事安排提供参考。     

克里雅河流域植被物候时空变化及影响因素

[目的] 探究克里雅河流域2000—2015年植被物候期时空变化规律,在气候变化背景下为该流域植被演变过程研究提供参考。[方法] 以MODIS MOD₀₉Q₁产品和当地气象站点数据为数据源,利用植被指数动态阈值法提取流域植被物候信息并进行空间趋势分析,以偏最小二乘回归方法分析克里雅河流域植被物候期与不同月份气象因子的相关性。[结果] ①研究期内植被生长期开始时间主要在第60—180 d之间,结束时间在第180—322 d之间,植被生长期长度在70~250 d之间。中游的人工绿洲植被生长期开始时间最早,结束时间最晚,植被生长时间最长。②2000—2015年克里雅河流域植被返青期整体呈提前趋势,变化速率均值为-1.3 d/10 a,植被枯黄期呈推迟趋势,生长期延长,其中以中游的变化趋势最为明显。③春季气温和降水量的升高促进植被返青期提前,秋季气温和降水量的升高会对植被枯黄期起到推迟作用。[结论] 克里雅河流域植被物候期在不同的海拔梯度上有明显的分布变化规律,中游人工绿洲植被的物候变化规律远异于自然植被物候变化规律,并且可能影响到了下游。     

北京植被净初级生产力对物候变化的响应

植被净初级生产力（Net Primary Productivity,NPP）对物候的响应是全球气候变化背景下的重要研究内容,气候变化对植物物候与NPP的影响仍需明了,物候的时空变异规律更需深入探讨。该研究基于2001-2020年MODIS归一化植被指数（Normalized Difference Vegetation Index,NDVI）数据提取北京植被物候信息,利用CASA（Carnegie-Ames-Stanford-Approach）模型模拟NPP,通过线性回归、趋势分析和结构方程模型等方法,阐明NPP与物候时空变化特征,探究气象因素和物候变化对NPP的影响。结果显示：1）2001-2020年超过70 %的区域出现生长季开始（Start of Growing Season,SOS）逐渐提前,平均每年提前0.53 d。超过90%的区域生长结束期（End of Growing Season,EOS）逐渐推迟,平均每年推迟0.51 d。2）SOS提前和生长季（Length of Growing Season,LOS）延长均对NPP增长产生显著影响（P<0.05）。SOS每提前1 d,NPP增长3.74 g/m2;LOS每延长1 d,NPP增长2.56 g/m2 。秋季EOS推迟对NPP变化影响不显著。3）春季和秋季,气候通过改变物候（SOS、EOS）对NPP的间接影响大于直接影响,而夏季温度和降雨对NPP的直接影响更大。该研究表明春季物候变化是NPP年际变异的重要驱动因子,春季物候提前导致NPP年总量增加。研究结果是都市区植被生产力如何响应气候变化认识的重要补充。     

气候变暖背景下西藏中南部苹果物候期变化及其气候影响因子分析

利用2001-2020年西藏泽当农业气象站苹果物候期和逐日平均气温(T_m)、最高气温(T_max)、最低气温(T_min)、气温日较差(DTR)、相对湿度(RH)、降水量(Pr)、日照时数(S)和≥0℃积温(∑T₀)等资料,采用线性回归、Pearson相关系数和逐步回归等方法,分析近20a西藏中南部苹果物候期及生长期长度的变化趋势,以及影响的主导气候因子,以期揭示西藏高原苹果物候期变化特征及其对气候变暖的响应。结果表明：2001-2020年西藏中南部苹果除可采成熟期以1.28d·a^-1的速率呈提前趋势外,其它物候期平均每年推迟2.83～7.64d;果实生长发育期长度、花期长度平均每年分别缩短8.92d和5.98d,而果树全生育期长度略有延长,速率为0.65d·a^-1。各物候期T_max趋于升高,T_min呈降低趋势,DTR显著增大;多数物候期RH、S呈显著减少趋势;Pr在可采成熟期前以增加为主,之后趋于减少。春季物候期主...     

1960-2015年淮河流域初终霜日时空变化分析

基于淮河流域1960-2015年61个气象站点地面0cm日最低气温资料,采用线性倾向估计、反距离加权、Mann-Kendall突变检验、滑动T检验方法,分析近56a淮河流域初霜日、终霜日和无霜期的时空变化特征及突变年份。结果显示：（1）研究期内,淮河流域平均初霜日期 、终霜日期和无霜期分别以2.15、2.49、4.38d·10a-1的速率呈推迟、提前、延长的趋势（P＜0.01）,其中,在20世纪90年代的变化最为显著（P＜0.01）,速率分别为16.38、5.34、20.6d·10a-1。（2）平均初霜日期在空间上呈北早、南迟,山区早、平原迟的分布;86.9%的站点初霜日期呈显著推迟趋势（P＜0.05）。终霜日期呈西南早、东北迟,平原早、山区迟的分布;83.6%的站点通过0.05水平的显著性检验,以3.44～5.92d·10a-1的速率呈提早趋势。无霜期随纬度和海拔升高而缩短;93.4%的站点通过0.05水平的显著性检验,变化率为3.56～7.59d·10a-1,无霜期整体延长。（3）11月8日线、4月1日线、220d等值线位置较其它各气候基准期和各年代分别偏北约1个和2个纬距,在32°N和34°N附近的偏北趋势最为明显,佐证了该区初霜日期整体推迟、终霜日期整体提前、无霜期整体延长的趋势。（4）初霜日期、终霜日期和无霜期分别在2002年、1995年和1998年发生突变。     

黄土高原半干旱区物候变化特征及其对气候变暖的响应

利用黄土高原半干旱区1994-2014年典型植物物候和气温资料,通过相关分析等方法分析典型植物展叶始期、展叶盛期、开花始期、开花盛期等春季物候期和叶初变期、叶全变期、落叶始期、落叶末期等秋季物候期的变化特征,以揭示黄土高原典型植物物候期对气候变暖的响应规律。结果表明:(1)在展叶期,草本植物历史最早和最晚出现日期相差20~36d,木本植物为20~38d;(2)草本植物春季物候期表现为明显的提前趋势,木本植物物候期的变化趋势差异较大,牡丹、旱柳展叶始期提前趋势明显;草本植物叶变色始期、黄枯始期以及木本植物落叶始期等秋季物候期的推迟趋势明显;(3)研究期内牡丹生长季的变化趋势不明显,其余典型植物生长季均一致表现为显著延长趋势(P0.05);(4)典型植物开花始期对前1月、前第3月(车前草为当月)以及春季(3-5月)气温的响应明显,春季气温每升高1℃,植物开花始期提前5~8d。研究结果表明黄土高原草本植物对气候变暖的响应比木本植物更明显,因此,在黄土高原生态脆弱区,选用对气候变化反应较为迟钝的杏树、榆树等乔木进行地区生态恢复重建较适宜。     

干旱胁迫对玉米物候及产量组成的影响及模拟研究

为了研究产量关键期干旱胁迫对玉米物候及产量和产量组成的影响,评估作物生长模型对干旱胁迫下玉米物候和产量模拟的效果,基于锦州农业气象试验站2011-2015年分期播种试验玉米产量和产量组成观测资料,尤其是2014年和2015年天然干旱胁迫试验数据和2015年玉米开花、吐丝物候加密观测资料,分析了产量关键期干旱胁迫对玉米物候及产量和产量组成的影响,评估了CERES-Maize模型对不同降水年型玉米产量和产量组成的模拟效果,提出了模型改进的方向。结果表明,2014年和2015年辽宁省西部地区在玉米开花期前后经历了较严重的干旱胁迫过程,干旱胁迫导致玉米吐丝延迟程度大于开花,90%以上的植株能到达开花阶段,但仅有45%~88%的植株能到达吐丝阶段,直接影响株籽粒数（不同播期下的玉米株籽粒数相差32%）及最终产量（产量下降33%~78%）。CERES-Maize模型对正常年玉米产量及产量组成的模拟效果较好,对干旱年的模拟效果较差,部分原因在于模型在模拟玉米物候时不对开花和吐丝期加以区别,只考虑了温度对花期的影响,而没有考虑干旱胁迫下玉米因开花-吐丝间隔增大、雌穗发育异常、物候期推迟而造成的减产作用。因此,玉米产量关键期干旱胁迫直接影响玉米物候（开花-吐丝期）,进而影响玉米穗粒数及最终产量;为提高干旱胁迫下作物模型的模拟评估能力,亟待开展干旱胁迫下基于冠层吐丝动态的玉米产量模拟研究。     

Grassland community composition drives small-scale spatial patterns in soil properties and processes

The presence and activity of individual plants can affect soil resource availability and microbial processes, and can influence the spatial scale over which soil properties vary. While soils have been found to differ under plants of differing growth form (i.e. grasses vs. trees), few studies have focused on small-scale soil differences under comparably-sized species. Here we investigate how two types of C-3 grasses influence patterns in soil properties and processes at scales of less than one meter in a California grassland. To understand how native perennial grasses differ from invasive annual grasses in their effects on soils, we used cross-semivariogram analysis to quantify the degree and scale of spatial heterogeneity in soil properties and processes in experimentally-seeded grasslands. We then used mapping techniques to correlate spatial patterns of soil properties and processes with the cover of annual and perennial grasses aboveground. We found that many soil properties and processes belowground were spatially-correlated with the aboveground presence of annuals or perennials. Soil moisture became more heterogeneous with increasing amounts of perennial cover, suggesting that perennial bunchgrass individuals take up more water and produce zones of resource depletion in comparison with soils directly under annual grasses. The association of belowground resources and activity with the two types of grass suggests that the historical shift from perennial to annual dominance in California grasslands led to changes in the small-scale spatial structure of soil properties and processes in these systems. These changes may alter ecosystem function and could potentially perpetuate invasive annual grass dominance.     

A comparison of multiple phenology data sources for estimating seasonal transitions in deciduous forest carbon exchange

There are currently numerous data sources available for estimating the timing of recurrent plant phenology transitions. We compared measurements from several phenology data sources to understand the relationship between phenology metrics derived from these data sources and the timing of seasonal transitions in net ecosystem exchange (NEE). We identified the timing of start, peak, end and the duration of the carbon uptake season, as well as the timing of the transitions from sink to source and source to sink using 11 years of NEE data from the University of Michigan Biological Station (UMBS). Using fitted logistic functions we identified proxy metrics for phenological transitions from the time series of Albedo, fraction of absorbed photosynthetically active radiation (fPAR), Plant Area Index (PAI), and MODIS normalized difference vegetation index (NDVI), enhanced vegetation index (EVI), and leaf area index (LAI) products of various spatial representations. We found that no single source of phenological data was able to accurately describe annual patterns of flux phenology. However, for each transition in NEE (e.g., start of season, transition to net sink), the metrics from one or more data sources were significantly (p < 0.05) correlated with the timing of these recurring events. A marginally significant trend toward a longer NEE carbon uptake period over 11 years was not detected by any of the metrics, primarily because none of the metrics were available for the full duration of the NEE data, and NEE did not show significant and consistent trends during the sub-sets of the time when proxy data were available. The results of our study highlight the relative strengths and weaknesses of each phenology data source for directly estimating seasonal transitions and interannual trends in carbon flux phenology of a deciduous forest.     

Soil microbial community composition as affected by restoration practices in California grassland

Agricultural practices have strong impacts on soil microbes including both the indices related to biomass and activity as well as those related to community composition. In a grassland restoration project in California, where native perennial bunchgrasses were introduced into non-native annual grassland after a period of intensive tillage, weeding, and herbicide use to reduce the annual seed bank, microbial community composition was investigated. Three treatments were compared: annual grassland, bare soil fallow, and restored perennial grassland. Soil profiles down to 80 cm in depth were investigated in four separate layers (0-15, 15-30, 30-60, and 60-80 cm) using both phospholipid ester-linked fatty acid (PLFAs) and ergosterol as biomarkers in addition to microbial biomass C by fumigation extraction. PLFA fingerprinting showed much stronger differences between the tilled bare fallow treatment vs. grasslands, compared to fewer differences between restored perennial grassland and annual grassland. The presence or absence of plants over several years clearly distinguished microbial communities. Microbial communities in lower soil layers were little affected by management practices. Regardless of treatment, soil depth caused a strong gradient of changing habitat conditions, which was reflected in Canonical Correspondence Analysis of PLFAs. Fungal organisms were associated with the presence of plants and/or litter since the total amount and the relative proportion of fungal markers were reduced in the tilled bare fallow and in lower layers of the grassland treatments. Total PLFA and soil microbial biomass were highly correlated, and fungal PLFA biomarkers showed strong correlations to ergosterol content. In conclusion, microbial communities are resilient to the grassland restoration process, but do not reflect the change in plant species composition that occurred after planting native bunchgrasses.     

Soil capability as a predictor of cropland change in Alberta,Canada from 1988 to 2010

Understanding the mutual influences between cropland use and soil characteristics is important in anticipating and planning for food production, environmental protection and resource sustainability. Numerous studies focus on the relationship between crop rotations and soil characteristics at a microscale, but fewer studies focus on the relationships between soil capability and cropland use and change at a medium scale. We explore how soil capability has influenced cropland changes over 22 yr, using statistical and land use transition analysis. Landsat images from the years 1988, 2002 and 2010 were used to map cropland changes by soil capability class within a pilot site in Alberta, Canada. Between the late 1980s and 2010: (i) the area of annual crops increased substantially while that of forest and summer‐fallow decreased; (ii) changes in cropland use among annual crops, perennial crops and summer‐fallow differed substantially depending on soil capability; and (iii) a transition from annual crops and summer‐fallow to perennial crops was more likely on land of poorer soil capability, whereas the transition from perennial crops and summer‐fallow to annual crops was more likely on land with higher soil capability. The changes in land use practices identified in this study indicate that producers are actively intensifying production on their best land to optimize profitability while simultaneously reducing the intensity of production on poorer land for either financial or environmental reasons, or both.     

气候变化对两种候鸟物候期的影响初探——以大丰市调查为例

选取大丰市气候(1960-2007年)及两种候鸟——家燕(Hirundo rustica)(1989-2007年)和四声杜鹃(Cuculus micropterus)(1995-2007年)的物候期资料,利用一元线性回归、多元逐步回归和M-K突变检验方法,分析了大丰市气候及两种候鸟物候期的趋势变化特征及候鸟物候期对气候变化的响应关系。结果表明:(1)近48a来大丰市年平均气温上升趋势明显,倾向率为0.18℃.10a-1(P0.01),于2004-2005年发生突变性增温;年平均风速呈极显著的下降趋势(P0.01),总日照时数、累积降水量的变化趋势不明显(P0.05);(2)物候期变化趋势表现在家燕始见期、四声杜鹃始鸣期均略有提早,家燕始、绝见期间隔时间略有延长,四声杜鹃间隔期以20.2d.10a-1的速率极显著缩短;(3)影响家燕始见期、间隔期的敏感气候因子是3月平均风速,影响其绝见期的敏感气候因子是5月平均温度;影响四声杜鹃始鸣期的敏感气候因子是5月总日照时数,影响其绝鸣期的关键气候因子是年平均风速、6月平均温度及7月累积降水量,影响间隔期的关键气候因子是年平均风速、6月平均温度及7月总日照时数。说明候鸟物候期对气候变化响应比较敏感,可作为气候变化的指示器。     

近15年来青海湖流域气温、降水变化对植被物候驱动分析

研究气候变化对植被物候的驱动分析,对于深入理解高寒植被适应全球气候变化具有重要意义。选取MCD12Q2植被物候数据,利用相关分析和GIS空间分析,对近15年来青海湖流域气温、降水变化与植被物候关系进行了研究。结果表明:近15年来青海湖流域植被返青期(start of growing season,SOS)、植被生长期长度(Length of growing season,LOS)、休眠期(Dormancy of growing season,DOS)与年均气温呈显著相关关系,其偏相关系数分别为-0.57～0.36,-0.89～0.81和-0.29～0.51; 与年均降水量偏相关系数分别为-0.58～0.38,-0.82～0.93和-0.23～0.23,表明流域植被SOS和LOS变化主要受年均气温和降水量共同影响,DOS变化主要受年均气温影响。青海湖流域植被SOS,LOS和DOS在空间上受气温、降水及其共同驱动的区域占比分别为33.7%,22.5%和36.67%,其受非气温—降水驱动的区域占比分别为66.3%,77.5%和63.33%; 沿海拔梯度方向上(海拔每上升100 m),年均气温上升1℃,植被SOS提前0.35 d,植被LOS延长0.15 d,植被DOS推迟0.25 d; 年均降水量增加1 mm,植被SOS推迟4 d,植被LOS缩短1.69 d; 植被DOS提前2.85 d。可见,近15年气温、降水变化对青海湖流域植被物候的驱动在空间上存在差异性,空间上植被物候主要受非气温—降水影响,海拔梯度上植被物候受气温和降水影响显著。