亚高山草甸华灰早熟禾对气候变化的响应

利用亚高山草甸华灰早熟禾生长发育的定位观测资料和相应的气象观测资料,分析了1985—2005年甘肃省玛曲县气候变化对牧草生长发育的影响.结果表明,研究期间,玛曲县降水量的年际变化呈下降趋势,其线性拟合倾向率为-9.895 mm·(10 a)^-1,降水量存在3 a的周期变化;气温的年际变化呈上升趋势,其线性拟合倾向率为0.341 ℃·(10 a) ^-1;华灰早熟禾生长季的干燥指数呈显著上升趋势,其线性拟合倾向率为0.036·(10 a)^-1,20世纪90年代初至2005年明显趋于干旱化.华灰早熟禾返青到籽实成熟约需140～150 d,期间对≥0 ℃积温、降水量、日照时数的要求分别为1000 ℃～1200 ℃、400～450 mm和1000～1100 h;华灰早熟禾在返青后54 d开始由缓慢生长转为迅速生长阶段,返青后第80天的生长速度达最大,返青后104 d开始由迅速生长又转为缓慢生长.受气候变暖的影响,华灰早熟禾抽穗期、开花期、成熟期、黄枯期每10年分别提前15 d、7～8 d、8～9 d、3 d.研究区的气候变化使该区华灰早熟禾产量变幅明显加大,产量的不稳定性增加.     

黄土高原半湿润区气候变化对冬小麦生长发育及产量的影响

利用黄土高原半湿润区西峰农业气象试验站冬小麦生长发育定位观测资料、加密观测和对应平行气象观测资料,分析气候变化对冬小麦生长发育的影响,以及冬小麦穗干重生长与气象条件的关系。结果表明,研究区域降水量年际变化呈波动变化,20世纪90年代降水量最少。降水量存在3、8a的年际周期变化。气温年际变化呈上升趋势,气温变化曲线线性拟合倾向率为0.325℃/10a。作物生长季干燥指数呈显著上升趋势,干燥指数变化曲线线性拟合倾向率为0.069/10a,20世纪90年代至2010年明显趋于暖干化。受气候变暖的影响,冬小麦播种期每10 a推后2—3d,返青期每10a提前4—5 d,开花期和成熟期每10a提前5—6 d。冬小麦越冬期每10a缩短5—6 d、全生育期每10a缩短7—8 d。冬小麦返青后第83天开始,穗干重的生长由缓慢转为迅速生长阶段,从返青后第101天开始,其生长从迅速生长又转为缓慢生长,在返青后的第87天,穗的干物质积累速度最大。由于气候变暖,冬小麦生育期大部分时段热量充足。播种—越冬前和拔节—开花期产量对气温变化的响应十分敏感;降水量的影响函数同温度的影响函数呈反相位分布,除成熟期降水量对产量形成为负效应外,其余时段降水量对产量影响均为正效应,而在冬小麦播种期和返青—拔节期产量对降水量变化的响应也十分敏感。     

气候变化对内蒙古鄂温克旗典型草原植物物候的影响

植物物候作为气候变化敏感的指示指标,已成为全球气候变化研究的焦点。利用内蒙古典型草原区鄂温克牧业气象试验站1959—2017年的气候资料和1983—2017年的植物物候观测资料,采用趋势倾向率和逐步回归等方法,分析了鄂温克旗气候变化特征,代表性牧草大针茅和羊草返青期、开花期、黄枯期及生长季的变化趋势,并通过偏相关分析探讨了气温、降水和日照时数与牧草生育期的关系,建立了主要牧草物候期的气候模型。结果表明:(1)鄂温克旗近60年平均气温呈极显著波动增加趋势,年降水量和年日照时数的变化很小;(2)30多年来,鄂温克旗大针茅和羊草返青期总体呈推迟趋势,倾向率分别为2.2 d/10a和1.4 d/10a;开花期的变化趋势不明显;黄枯期分别以2.8 d/10a和1.5 d/10a的趋势提前;生长季长度呈明显缩短趋势;(3)3月和4月气温是影响研究区牧草返青最主要的气候因子,气温升高返青期提前;前2个月降水量对大针茅开花期的影响较大;气温升高使得黄枯期提前,而降水量增加则使得黄枯期推迟。     

西北温凉半湿润区气候变化对马铃薯生长发育的影响——以甘肃岷县为例

利用西北温凉半湿润区马铃薯生长发育定位观测资料、加密观测和对应平行气象观测资料,分析气候变化对马铃薯生长发育的影响,以及马铃薯块茎生长与气象条件的关系。结果表明,研究区域降水量年际变化呈下降趋势,降水量变化曲线线性拟合倾向率为-8.329 mm/10 a。降水量存在3 a的年际周期变化。气温年际变化呈上升趋势,气温变化曲线线性拟合倾向率为0.144℃/10 a。作物生长季干燥指数呈显著上升趋势,干燥指数变化曲线线性拟合倾向率为0.042/10 a,20世纪90年代初至2007年明显趋于干旱化。马铃薯播种到采收约需150-168d,需≥0℃积温2000-2300℃,降水量400-500mm,日照时数900-1100h。马铃薯在播种后105d开始,块茎由缓慢生长转为迅速生长阶段;在播种后127d,块茎生长速度最大;播种后149d开始,块茎生长从迅速生长又转为缓慢生长。对马铃薯生长发育全生育期而言,受气候变暖的影响,马铃薯花序形成期每10 a提前8-9d,开花期每10 a提前4-5d。气温对马铃薯产量形成除采收期外,其余为负效应,块茎膨大期对气温变化十分敏感;而降水量的影响函数同热量的影响函数呈反相位分布,除出苗期和采收期降水量为负效应外,其余时段降水量对马铃薯产量形成均为正效应,马铃薯分枝期到开花期对降水量变化十分敏感。     

近20年青藏高原东北部禾本科牧草生育期变化特征

利用1988—2010年青藏高原东北部地区5个站点牧草生育期地面观测数据,分析了近20年代表性牧草返青、开花、黄枯期及生长季的变化趋势,并通过偏相关分析探讨了气温和降水对牧草生育期的关系。结果表明,近20年青藏高原东北部牧草生育期北部推迟南部提前的特征明显。南部的三江源区域返青、开花与黄枯期总体呈显著提前趋势,其中曲麻莱羊茅返青期提前的倾向率达到-4 d/10 a,开花期为-13 d/10 a,黄枯期达到-9 d/10 a,且均通过0.01的显著性检验水平。北部环青海湖区域的海北西北针茅生育期则表现出一定的推迟趋势。生长季长度北部地区延长,而南部除甘德(垂穗披碱草)外均呈明显缩短趋势。近20 a黄枯期的变化幅度明显大于返青期,使得生长季长度的变化更多地受黄枯期变化的影响。1月和3月气温是影响研究区牧草返青最主要的气候因子,气温增高返青提前。开花期南北差异明显,北部与同期气温呈明显负相关关系,南部则主要与开花前2—3个月的降水量密切相关,降水增多大部地区开花期提前。此外,降水也是各地牧草黄枯的主要影响因子。     

气候变化对内蒙古中部草原优势牧草生长季的影响

研究温性典型草原优势牧草生长季与气候因子变化的关系,对于监测草地环境变化及保护利用,评估区域气候变化对优势牧草生长的影响,指导畜牧业生产等具有重要的科学意义和实践价值.基于内蒙古中部草原3个牧业气象试验站1983-2009年克氏针茅和羊草的物候期、气象资料,对返青、黄枯日期、生长季与气温、降水量之间的关系进行了统计分析.结果表明:(1)27a间,该区的年、春季、夏季和秋季平均气温均呈显著升高趋势,春季升温幅度最大,气候倾向率为0.71-0.84℃/10a;各时段降水量变化除春季呈微量增加趋势外,总体呈减少态势.可见,内蒙古中部温性典型草原区暖干化趋势明显.(2)27a间,锡林浩特克氏针茅和羊草返青日期表现为推后趋势,并与4月降水量呈显著正相关;镶黄旗和察右后旗克氏针茅和羊草返青日期呈提前趋势,并与3-5月气温、降水量呈显著负相关,气温每升高1℃、降水量每增加10mm,优势牧草返青日期约提前3.0-5.1d和1.3-2.1d.(3)该区克氏针茅和羊草黄枯日期均呈提前趋势,与8-9月气温均呈显著负相关,降水量为正相关,气温每升高1℃,克氏针茅黄枯日期提前1.7-10.7 d,羊草黄枯日期提前3.5-11.3d,降水量的影响相对较弱.(4)该区克氏针茅生长季延长趋势明显,羊草生长季缩短趋势明显.克氏针茅生长季与4-10月均温正相关系数最大,羊草生长季与水热系数的正相关系数最大.     

内蒙古东部草原优势牧草生长季对气象因子变化的响应

研究区域气候变化对草原牧草生长的影响,对于指导农牧业生产及应对气候变化等具有重要的实践价值.基于内蒙古东部草原34个气象站50年和3个牧业气象试验站27年的气象及牧草物候期数据,研究了气候变化对优势牧草生长季的影响.结果表明:(1)研究区域年、春季、夏季和秋季平均气温均呈显著升高趋势,降水量变化春季呈微升的态势,其余时段呈微降的趋势;气候暖干化趋势明显.(2)春季气温升高有促进优势牧草返青日期提前的效应,气温每升高1℃,鄂温克旗、额尔古纳市羊草(Leymus chinensis)和贝加尔针茅(Stipa baicalensis)返青日期提前1.7～1.9d.(3)夏、秋季气温升高均有促进优势牧草黄枯日期推后的效应,气温每升高1℃,额尔古纳市羊草和贝加尔针茅黄枯日期推迟2.0～2.3d.(4)夏、秋季气温每升高1℃,额尔古纳市贝加尔针茅生长季分别延长3.3和3.7d;在巴雅尔吐胡硕秋季气温每升高1℃,冰草(Agropyron cristatum)生长季缩短2.8d.     

黄土高原半干旱区气候变化对春小麦生长发育的影响——以甘肃定西为例

利用黄土高原半干旱区春小麦生长发育定位观测资料、加密观测和对应平行气象观测资料,分析气候变化对春小麦生长发育的影响,以及春小麦穗干重生长与气象条件的关系。结果表明,研究区域降水量年际变化呈下降趋势,降水量变化曲线线性拟合倾向率为-15.796 mm/10a。降水量存在3 a、6 a的年际周期变化。气温年际变化呈上升趋势,气温变化曲线线性拟合倾向率为0.362℃/10a。作物生长季干燥指数呈显著上升趋势,干燥指数变化曲线线性拟合倾向率为0.12/10a,20世纪90年代初至2009年明显趋于干旱化。春小麦播种到成熟约需110-130 d,期间≥0 ℃积温为1500-2000 ℃,降水量为150-200 mm,日照时数为800-1300 h。春小麦在播种后38 d开始,穗干重由缓慢生长转为迅速生长阶段;在播种后50 d,穗干重生长速度最大;播种后63 d开始,穗干重生长从迅速生长又转为缓慢生长。对春小麦生长发育全生育期而言,受气候变暖的影响,乳熟-成熟期每10 a缩短2-3 d、全生育期每10 a缩短4-5 d。气温对春小麦产量形成除出苗期和成熟期外,其余为负效应,孕穗期对气温变化十分敏感;降水量的影响函数同热量的影响函数呈反相位分布,除出苗期和成熟期降水量为负效应外,其余时段降水量对春小麦产量形成均为正效应,春小麦拔节-抽穗期对降水量变化十分敏感。     

长江源区高山嵩草物候与生物量动态及其对气候变化的响应

利用青藏高原腹地江河源头的曲麻莱县气象站1994～2004年观测的高寒嵩草草甸优势种高山嵩草的生育期、高度、产量等指标与同期气象资料,通过定量分析研究较长时段的物候及生物量变化特征,以揭示其对气候变化的响应.结果表明:(1)高山嵩草返青期和开花期的变化总体均呈"W"形,在区域气候变暖背景下,植物物候表现为返青期提前,开花期和枯黄期推迟,整个生长季延长.(2)高山嵩草的生物量变化在10年间呈明显的波动趋势,各月最高生物量均出现在1999年,最低生物量出现在1994年.(3)高山嵩草物候期与生长季各月气温呈显著的正相关关系(P<0.001),与月降水量呈弱正相关关系(P>0.05);月均气温成为本区草本植物发芽生长的先决条件,且6～8月气温与植物萌动的相关性最大.(4)生长季6～8月高山嵩草生物量鲜重和干重均与月均气温呈显著正相关,鲜重仅与月降水量呈显著正相关关系,在青藏高原的高寒区,温度比降水对植物产量的影响更大.     

青海湖流域草地植被动态变化趋势下的物候时空特征

植被物候不仅直接受气候变化的影响,还反作用于气候变化。因此,明确植被物候变化的驱动机制对于进一步研究气候变化与物候的相互作用具有重要的意义。选取位于青藏高原东北部的青海湖流域,利用MODIS 16d增强植被指数(EVI)合成数据,来分析草地物候时空格局特征以及不同EVImax变化趋势下草地物候期(返青期、枯黄期及生长季)的变化趋势。研究得到以下结果:(1)在气候变化和人类活动等因素的共同作用下,青海湖流域的EVImax变化呈现多元化趋势,EVImax增加、不变、降低趋势并存;(2)1990—2012年期间,流域内温度上升、降水量增加趋势显著,温度上升速率为0.42—0.83℃/10a,降水量增加速率为43.20—44.68 mm/10a。刚察、天峻气象站草地返青期在2001—2012年期间呈现延迟趋势,枯黄期变化趋势不显著,生长季呈现缩短趋势;(3)流域内草地返青从4月下旬持续到6月上旬,枯黄期从8月中旬持续到10月上旬,青海湖东岸、南岸、布哈河入湖口区域以及流域西部山坡和平坦的谷底地区牧草最早进入返青期,返青空间格局呈现由湖岸向四周高海拔地区延伸趋势,草地枯黄空间格局与返青期相反;(4)不同EVImax变化趋势下,草地返青期、枯黄期、生长季变化趋势表现出差异。草地EVImax降低趋势下,牧草返青期呈现提前趋势,枯黄期延迟,生长季延长;EVImax增加趋势下,牧草返青期延迟,枯黄期变化不明显,生长季缩短;EVImax不变区、农田的返青与枯黄期变化趋势并不明显,但是农田生长季缩短趋势较明显。     

Variation in onset of summer dormancy and flowering capacity along an aridity gradient in Poa bulbosa L., a geophytic perennial grass

Variation in the onset of summer dormancy and flowering capacity of 16 populations of Poa bulbosa, collected along a steep north-south aridity gradient in Israel (810-110 mm rain year(-1)), was studied under controlled conditions in a phytotron (16 h daylength, 22/16 degrees C day/night) and under natural conditions in a garden experiment in a net-house. Plant age at the onset of dormancy varied markedly amongst populations (7-16 weeks under controlled conditions) and was positively correlated with mean annual precipitation at the site of origin of the population, i.e. dormancy was earlier as aridity increased. Flowering capacity in the different populations was negatively correlated with rainfall in the original habitat and, consequently, also with the age at onset of dormancy, i.e. the lower the mean annual precipitation, the earlier the onset of dormancy and the higher the proportion of flowering plants and panicles per plant. Differences in xeromorphic leaf traits were also observed among populations from locations differing in aridity. Plants from the more arid sites (110-310 mm year(-1)) generally had greyish and curved leaves, whereas plants from more humid sites (500-810 mm year(-1)) tended to have green and straight leaves. Thus, plants with curved and/or greyish leaves generally had a higher flowering capacity and entered dormancy earlier than plants with straight and/or green leaves. The significance of the association among these traits for the adaptation of P. bulbosa to increasing aridity is discussed.     

Simulated global changes alter phosphorus demand in annual grassland

In the Jasper Ridge Global Change Experiment – an annual grassland with elevated carbon dioxide (CO₂), nitrate deposition, temperature, and precipitation – we used six indices of phosphorus (P) limitation to test the hypothesis that global changes that increase net primary production (NPP) increase P demand or limitation. All indices indicated that nitrate deposition, the only factor that stimulated NPP, increased P demand or limitation: (1) soil phosphatase activity increased by 14%; (2) P concentration in green and (3) senescent leaves of the dominant grass genus, Avena , dropped by 40% and 44%, respectively; (4) N : P ratios in green and (5) senescent Avena widened by 99% and 161%, respectively; and (6) total aboveground plant P decreased by 17% with elevated nitrate deposition. The other three factors, which did not stimulate NPP, did not increase P demand: based on two indices, enhanced precipitation decreased P demand (11% decrease in phosphatase activity, 19% increase in total aboveground P), and there was no evidence that elevated CO₂ or temperature altered P demand. In a meta-analysis to assess the generality of P constraints on growth increases from global change factors, we found that six of 11 N-limited ecosystems responded to N deposition with enhanced P limitation or demand, but did not detect significant effects of elevated CO₂ or warming.     

松嫩平原碱化草甸星星草种群分蘖株延长生殖生长的表型可塑性调节

在松嫩平原碱化草甸,采用大样本随机取样的方法,研究了不同时间到达抽穗初期、抽穗期、开花期和乳熟期的星星草种群生殖分蘖株数量性状的可塑性及其调节规律.结果表明：除在开花期存在一定的波动外,在每5 d的时间里,随着生殖生长时间的延长, 星星草种群在抽穗初期、抽穗期和乳熟期的生殖分蘖株高、分蘖株生物量、花序长和花序生物量均依次显著增加.各生育期的星星草种群生殖分蘖株高与花序生物量呈显著正相关,而与生殖分配呈显著负相关.随着生殖生长时间的延长,抽穗初期、开花期和乳熟期的星星草花序生物量随着分蘖株高增加,其幂函数的增长速率均呈增大趋势.生殖生长时间延长10 d,其抽穗初期和抽穗期的生殖分配直线下降速率分别降低了43.2%和44.31%;延长5 d,乳熟期的下降速率降低了130%.表明星星草种群分蘖株生殖生长的表型可塑性调节遵循着一定的规律.     

黄土高原半干旱区气候变化及其对马铃薯生长发育的影响

基于黄土高原半干旱区1988-2008年马铃薯生长发育定位观测资料、2007-2008年加密观测和1957-2008年地面气象观测资料,研究了气候变化对马铃薯生长发育的影响.结果表明：1957-2008年,研究区年降水量呈下降趋势,降水量变化曲线线性拟合倾向率为-13.359 mm·(10 a)^-1;年均气温呈上升趋势,年均气温变化曲线线性拟合倾向率为0.239 ℃·(10 a)^-1;作物生长季干燥指数呈显著上升趋势,干燥指数变化曲线线性拟合倾向率为0.102 ·(10 a)^-1.从播种后第96 天开始,马铃薯块茎由缓慢生长转为迅速生长,在播种后第110天,马铃薯块茎的生长速度达最大;从播种后第124 天开始,马铃薯块茎从迅速生长又转为缓慢生长.从播种至出苗期的间隔日数为每10年缩短1～2 d,花序形成至采收期和全生育期的间隔日数均为每10年延长9～10 d.气候变暖导致马铃薯生育前期的营养生长阶段缩短以及生殖生长阶段和全生育期延长.     

气候条件对典型草原牧草生长发育影响浅析

采用兴安盟扎赉特旗2004年～2011年气候生态环境监测站监测的典型草原牧草生长发育及地上生物量等基本资料。典型草原主要牧草种类有贝加尔针茅、野古草、羊草等禾草,伴生中旱生杂草、灌木及半灌木组成,草丛一般高30～50 cm。本文详细分析了当地气候条件对典型草原牧草生长发育及产量的影响。结果表明,典型草原牧草的高度、盖度及地上生物量受温度和降水量影响最明显,其中降水量的影响超过温度的影响。降水量多的年份地上生物量明显增加,而干旱年份地上生物量减少,其最大值一般出现在7月份,并滞后于降水量最大值。     

Plant responsiveness to variation in precipitation and nitrogen is consistent across the compositional diversity of a California annual grassland

Question: How does responsiveness to water and Nitrogen (N) availability vary across the compositional and functional diversity that exists in a mesic California annual grassland plant community? Location: Northern California annual grassland. Methods: A mesocosm system was used to simulate average annual precipitation totals and dry and wet year extremes observed in northern California mesic grasslands. The effects of precipitation and N availability on biomass and fecundity were measured on three different vegetation types, a mixed grass forb community, and a forb and a grass monoculture. The treatment effects on plant community composition were examined in the mixed species community. Results: While growth and seed production of the three vegetation types was inherently different, their responses to variation in precipitation and N were statistically similar. Plant density, shoot biomass, and seed production tended to increase with greater water availability in all vegetation types, with the exception of a consistent growth reduction in high precipitation (1245 mm) plots in the first year of the study. Shoot biomass responded positively to N addition, an effect that increased with greater water availability. Nitrogen addition had little effect on plant density or seed production. In the mixed grass‐forb community, biomass responsiveness to water and N treatments were consistently driven by the shoot growth of Avena barbata, the dominant grass species. Conclusions: Vegetation responses to changes in precipitation and N availability were consistent across a range of composition and structural diversity in this study. Plant growth and seed production were sensitive to both increased and decreased precipitation totals, and the magnitude of these responses to N availability varied depending on soil moisture conditions. Our results suggest the impacts of changing precipitation regimes and N deposition on annual productivity of California grasslands may be predictable under different climate scenarios across a range of plant communities.     

Seasonal precipitation and continentality drive bimodal growth in Mediterranean forests

Tree phenology is sensitive to climate warming and changes in seasonal precipitation. Long xylogenesis records are scarce, thus limiting our ability to analyse how radial growth responds to climate variability. Alternatively, process-based growth models can be used to simulate intra-annual growth dynamics and to better understand why growth bimodality varies along temperature and precipitation gradients. We used the Vaganov-Shashkin (VS) growth model to analyse the main climatic drivers of growth bimodality in eight trees and shrubs conifers (four pines and four junipers) across Spain. We selected eleven sites with different continentality degree and spring/autumn precipitation ratios since we expected to find pronounced bimodal growth in less continental sites with spring and autumn precipitation peaks. The VS model successfully simulated annual growth rates at all sites as a function of daily temperature and soil moisture data. Bimodal growth patterns clustered into less continental sites showing low spring/autumn precipitation ratios. This finding agrees with observed climate-growth associations showing that growth was enhanced by wet-cool winter-to-spring conditions, but also by wet autumn conditions in the most bimodal sites. We observed a stronger growth bimodality in pines compared to junipers. We discuss the spatial variability of climate drivers in bimodality growth pattern and how increasing continentality and shifts in seasonal precipitation could affect growth patterns. Bimodality could be an advantageous response to overcome summer drought in Mediterranean forests. The ability of some species to reactivate growth during autumn might determine their capacity to withstand increasing summer aridity.     

荒漠草原区不同生活型植物生长对降水变化的响应

在全球气候变化背景下,降水变化对植物群落动态将产生深远的影响。以黄土高原西部荒漠草原为对象,通过野外降水控制试验,研究不同生活型植物丰富度、密度、盖度、高度和地上生物量对降水变化的响应。结果表明: 降水处理对一年生草本植物的丰富度、密度、盖度的影响在降水试验第3年(2015年)达到显著水平,以减水处理最低,植物高度对降水变化的响应更敏感,3年间,均以减水40%处理最低;植物生长和地上生物量对减水处理的负响应幅度大于对增水处理的响应。多年生草本植物的丰富度、密度和盖度在第3年以减水处理显著低于增水40%处理,但与对照无显著差异;植物高度3年间均以减水40%处理最低;丰富度、盖度、高度对减水处理的负响应幅度大于对增水处理的正响应,但地上生物量对增水40%处理的正响应较强。灌木的丰富度、密度、盖度和地上生物量对增减水20%处理的正响应最明显,可能与灌木在该处理分布相对集中有关。降水减少抑制了草本植物的生长,但对一年生草本植物的抑制作用更强,降水增加在一定程度上促进了多年生草本植物的生长和生物量积累。一年生草本植物的生长和生物量随降水年际变异波动明显,灌木受降水改变的影响相对较小,降水变化对黄土高原西部荒漠草原植物群落组成与功能将产生显著的影响。     

东北草原羊草种群结实特性与气候年变化的关系

Leymus chinensis（Trin.）Tzvel. is a fine herbage, which is a perennial rhizome grass species with high potentiality of vegetative propagation. The quantitative characters of fruit-bearing and grain weight of the population were successively investigated in three fixed stands from 1983 to 1998,analyzing the relationship between these characters and the climatic factors in different growing and developing stages. Certain degree of correlations were found between the number of seeds and grain weight of the population and different time of sunshine, temperature and rainfall accumulation before and during the growing and developing stages. From vegetative to reproductive growth of the tiller, including flowering, pollination, fertilization, and ovule development and seed formation, lower accumulated temperature and longer day light during the early growth season promoted fruit-bearing of the population, and vice versa. From turning green to fruit-ripening stage, longer sunshine duration benefited while higher accumulated temperature inhibitted nutrient deposition in the grain. Furthermore rainfall was also good to nutrient collection in the grain from turning green to milky stage,not from milky stage to mature stage. Growth and development of the winter tillers would affect the flowering, fruit-bearing, as well as the quality and quantity of seed production in the following year. Therefore, the number of fruit-bearing and the grain weight of the population could be predicted by the length of sunshine duration from August to September of the previous year and amount of rainfall in May of the present year,but the quantitative variation that estimated by simple climatic factor model was only 29.27%-35.76%.     

东北草原羊草种群结实特性与气候年变化的关系

对３个固定样地的羊草（Ｌｅｙｍｕｓ ｃｈｉｎｅｎｓｉｓ（Ｔｒｉｎ．）Ｔｚｖｅｌ．）种群连续１２￣１６年的调查和测定及其与不同生长发育阶段气候因子的相关分析,表明羊草种群结实数量和籽实重量均与形成这些性状的生育期内,及其以前各生育期不同阶段的光照时间、积温、降水量有着一定程度的相关关系。从分蘖株的营养生长到生殖生长,包括开花、授粉、受精、胚珠发育为种子形成的整个过程中,较低的温度和生长季前期较多的光