高寒植物叶片性状对模拟降水变化的响应

降水变化对高寒草甸生态系统产生了显著影响,植物叶片性状特别是叶脉特征对降水变化非常敏感,然而高寒植物叶片性状特征如何响应降水变化还知之较少。采用集雨棚模拟增减50%降水的条件,以高寒草甸8种主要植物叶片为研究对象,研究了降水变化对叶片的叶脉率、叶脉密度、叶片大小、比叶质量、叶片总有机碳含量、叶片全氮含量、叶片碳同位素相对含量和碳氮比等叶片性状的影响。发现增水显著增加了植物的叶片大小、稳定碳同位素千分值、总有机碳含量、全氮含量,但显著降低了叶脉密度;而减水显著降低了叶片大小、稳定碳同位素千分值。植物叶片性状各指标对降水变化的响应存在协同变化和相互制约。不同水分生态类型的植物对降水变化的响应存在差异,中生植物通过增加叶片大小和减少叶脉密度积极应对降水的增加,矮生嵩草的叶片大小分别增加了200.3%,叶脉密度减小了17.5%,而旱中生植物通过减少叶片大小和增加叶脉密度应对降水的减少,垂穗披碱草和异针茅的叶片大小分别减少54.9%和30.7%,其叶脉密度分别增加25%和22.4%。羽状叶脉植物增加叶脉密度和稳定碳同位素千分值以适应增水条件,花苜蓿、异叶米口袋的叶脉密度的增加了7.8%和4.0%,稳定碳同位素千分值增加2.5%和3.3%,但增水条件下平行叶脉植物的叶脉密度不变或降低和稳定碳同位素千分值保持不变;减水增加了平行叶脉植物叶脉密度并减低了稳定碳同位素千分值,异针茅的叶脉密度增加了22.4%,稳定碳同位素千分值减小2.9%,而对羽状叶脉植物的叶脉密度和稳定碳同位素千分值减少或不变。植物叶片性状对增水的敏感性显著大于对减水的敏感性,增水的效应约为减水的2倍;叶片大小的敏感性显著大于其它叶片性状,约为其它叶片性状的10倍。因此,植物在应对短期降水变化时,植物形态可塑性的作用凸显,放大或缩小叶片大小是植物应对降水变化的最有效的途径,但是不同水分生态类型和叶脉类型植物可塑性的方向存在显著差异。     

青藏高原高寒草甸夏季植被特征及对模拟增温的短期响应

以青藏高原高寒草甸为研究对象,研究了草甸植被夏季生长动态特征;同时采用红外辐射器模拟增温的方法,探讨了草甸植被对增温的短期(1a)响应.结果表明:(1)高寒草甸夏季植被高度与地下生物量、总生物量相关性不显著,盖度与二者相关性极显著;高度对地上生物量影响较大(R=0.892,P＜0.01),盖度对地下生物量(R=0.883,P＜0.01)和总生物量(R=0.888,P＜0.01)影响较大.(2)高寒草甸夏季植被地上部分和地下部分表现出不同的生长模式,地上部分近似等速生长(幂指数为1.011),地下部分则表现为异速生长(幂指数为0.459),但整体呈现异速生长(幂指数为0.473).(3)高寒草甸夏季植被地上生物量(P＜0.05)在6月份较地下生物量(P＞0.05)对环境更为敏感,且一年之后地上-地下生物量均呈减小趋势,这与空气温度、土壤温度和土壤水分的显著减小密切相关.(4)红外辐射器在高寒草甸的增温度效果较好,空气、地表、土壤温度都随增温幅度增强而增加;短期增温对高寒植被有正效应(T0-T1),而温度持续升高则对植被产生负效应(T1-T2);各植被指标的方差分析都未达到显著水平,表明短期增温对该植被影响不显著.     

高寒草地类型和海拔对濒危藏药独一味生长繁殖特征的影响

为探讨高寒草地类型和海拔对独一味(Lamiophlomis rotata)生长与繁殖特征的影响,在玛曲三种草地类型和三个海拔梯度下进行随机样方调查和样品收集,并对独一味的生长和繁殖特征指标进行测定.结果表明:(1)不同草地类型中,独一味地上部特征表现为高寒沼泽化草甸>高寒山坡草甸>高寒灌丛草甸,地下部特征表现为高寒沼泽...     

植物物候对气候变化的响应

植物物候的变化可以直观地反映某些气候变化,尤其是气候变暖.植物生长节律的变化引起植物与环境关系的改变.生态系统的物质循环（如水和碳的循环）等过程将随物候而改变.不同种类植物物候对气候变化的响应的差异,会使植物间和动植物间的竞争与依赖关系也发生深刻的变化.目前欧洲、美洲、亚洲等许多地区均有关于春季植物物候提前,秋季物候推迟,使植物的生长季延长,从而提示气候变暖的趋势.植物物候的模拟模型构成生态系统生产力模型的重要部分.     

模拟增温改变青藏高原植物繁殖物候及植株高度

气候变化显著影响了高寒植物物候期及生长模式, 从而改变了高寒生态系统功能。而高寒植物物候期和生长状况对气候变化的响应程度, 与其自身资源分配策略有关。为了更好地探究气候变化下高寒植物繁殖物候及生长的规律, 该研究以青藏高原高寒草甸为研究对象, 按生物量从高到低选取15种常见植物, 其生物量之和占样地总生物量80%以上, 采用红外辐射器模拟增温的方法, 利用同质园实验, 观测无种间竞争条件下, 增温2年间植物返青、现蕾、开花以及结实物候, 并监测了植株高度。研究结果表明: (1)在功能群水平上, 增温使豆科类植物的返青、现蕾和开花时间分别显著提前了(8.21 ± 1.81)、(9.14 ± 2.41)和(10.14 ± 2.05) d, 使其开花持续时间显著延长了(6.14 ± 1.52) d, 而增温对其他功能群物候事件无显著影响。增温对高寒植物物候的影响存在种间及年际间差异, 但总体上增温使大多数高寒植物繁殖物候提前并且开花持续时间延长, 将更多的资源更多地分配到繁殖生长上。(2)增温显著降低了杂类草植物的植株高度(平均降低(3.58 ± 0.96) cm), 但对豆科类、禾草类及莎草类功能群植株高度没有显著影响。 增温对高寒植物植株高度的影响存在显著的种间差异以及年际差异。综上所述, 未来气候变暖背景下, 青藏高原高寒植物群落可能更早进入繁殖阶段, 从而降低在营养生长上的资源分配。另外, 由于各物种繁殖能力和营养生长对温度变化响应的差异, 气候变暖将导致高寒植物群落中各物种盖度的变化, 进而改变群落物种组成, 从而影响高寒生态系统的功能。     

川西北高寒草地3种主要植物的生长及物质分配对温度升高的响应

在野外自然条件下采用开顶式生长室模拟增温的方法, 研究了增温对川西北高寒草地3种主要植物(单子叶草本植物垂穗披碱草(Elymus nutans)和双子叶草本植物尼泊尔酸模(Rumex acetosa)和鹅绒委陵菜(Potentilla anserina))的生长及物质分配的影响。研究结果表明, 增温对3种植物的生长产生了显著影响, 垂穗披碱草和尼泊尔酸模的比叶面积和生物量积累在增温后显著增加, 而鹅绒委陵菜在增温后显著减少。在各组分中, 增温处理使尼泊尔酸模的叶生物量显著增加, 根生物量却显著下降, 而鹅绒委陵菜叶和茎的生物量在增温后显著减少, 根生物量却显著增加。增温对尼泊尔酸模各组分的养分含量产生了显著影响, 其中, 根部碳含量在增温后显著增加, 而氮含量在增温后显著减少。增温对尼泊尔酸模和鹅绒委陵菜的生物量在各组分中的分配产生了显著影响, 增温显著增加了尼泊尔酸模的叶重比(LMR)、根重比(RMR)和地下生物量/地上生物量(R/S), 而茎重比(SMR)在增温后却显著降低; 增温显著增加了鹅绒委陵菜的RMR和R/S, 而SMR和LMR在增温后却显著降低。增温对尼泊尔酸模和鹅绒委陵菜各组分中的碳、氮分配产生了显著影响, 增温显著增加了碳、氮在尼泊尔酸模叶片的分配比例, 并且使尼泊尔酸模根部的碳分配比例也显著增加, 而茎部的碳、氮分配比例却显著减少; 增温显著减少了碳在鹅绒委陵菜叶片的分配比例, 而根部的碳、氮分配比例却显著增加。     

模拟微重力条件对植物幼苗生长的影响

与正常重力下生长的植物幼苗对照相比,在竖直平面内径回转器连续做１２０ｈ圆周回转的草莓和香石竹幼苗的生长状况发生如下变化：（１）株高和叶片数有所增加;（２）草莓的叶绿素含量降低４７．５％,香石竹叶绿素含量增加４．３％;（３）回转后两种幼苗的叶绿素的主要吸收峰位不变,而每个峰位吸收强度有所增加;（４）两思苗的叶片快速荧光动力学参数,回转后除ＣＡ／Ｆ０外,Ｆｖ／Ｆｏ、Ｆｖ／Ｆｍ和Ｔ１／２均有提高;（５）     

青藏高原高寒湿地GPP变化特征及对生长季积温的响应

基于涡度相关系统,利用2004—2016年的涡度相关系统观测资料,做了青藏高原高寒湿地生长季总初级生产力(GPP)在不同时间尺度上对生长季有效积温(GDD)响应的研究。结果表明:高寒湿地生态系统在生长季的日GPP、GDD与月际GPP、GDD都表现为先增大后减小的单峰变化趋势,都在7月或8月达到峰值,在5月达到最小值。在整个生长季尺度上,GPP与GDD变异性较大,没有明显的变化趋势。2004—2016年整个生长季GPP与GDD的均值分别为(458.82±25.78) gC m^-2季^-1和(1060.89±84.07)℃。在日尺度、月尺度、生长季尺度上,GPP与GDD都呈极显著正相关关系(P<0.01)。但是,通过比较生长季分别每个月GPP与GDD的关系发现,5、9月的GPP与GDD没有显著相关性(P>0.05),而在7月相关性最为显著(P<0.01)。整体上看,高寒湿地生态系统植被的总初级生产力与热量条件表现为正相关关系,由此说明在全球气候变暖的背景下,将会提高青藏高原高寒湿地生态系统植被的光合生产能力。     

气候变化对内蒙古草原典型植物物候的影响

自然物候期是气候变化最直观的植物信号记录,自然物候变化是气候与自然环境变化的综合指标。基于1983—2009年内蒙古草甸草原、典型草原和荒漠草原区典型植物马兰草、霸王、贝加尔针茅和羊草生长期物候观测资料和同时段的气象观测资料,利用数理统计等方法,分析了不同草原区典型植物物候期与气候要素间的相互关系,结果表明:(1)1983—2009年内蒙古草原区植物物候期总体呈提前趋势,但地域差异明显,典型草原区植物萌芽返青、开花及黄枯期等物候提早趋势最为明显,说明不同草原区植物物候对气候变暖的区域响应不同。(2)内蒙古草原区植物物候期与气候变化密切相关。春季3—5月累积气温与植物萌芽返青期和开花期呈显著负相关,与日照时数为正相关,降水量对其影响不同草原区差异较大。荒漠草原和典型草原区植物黄枯期早晚与黄枯前1—2个月平均气温呈显著负相关,草甸草原区植物黄枯期与前1—2个月的降水量和日照时数有关,与气温关系不显著。(3)随着气候变暖,马兰草生长期缩短,霸王、贝加尔针茅和羊草生长期延长,其中典型草原区主要植物针茅生长季延长趋势最为明显,荒漠草原次之,草甸草原延长最少。     

高寒草甸植物物候对温度变化的响应

植物物候是植物为适应其生长环境而呈现的规律性变化,是气候变化的指示器。为了解高寒植物物候对温度变化的响应,利用1997—2010年青海湖海北高寒草原生态监测站群落优势种矮嵩草物候观测资料和同时段的气象资料,应用偏最小二乘(PLS)回归定量分析了植物物候期变化特征、趋势及其与气温间的相互关系。结果表明:①1997—2010年青海湖地区年均温度总体上升,倾向率为0.5℃/10a,其中年均最高温度和最低温度呈现出非对称型变化,最低温度显著升高且高于年均温升幅,倾向率为0.7℃/10a(P0.05),而年均最高温度无明显变化。②1997—2010年间,矮嵩草平均返青期和枯黄期分别为4月18日和10月2日,矮嵩草返青期推迟,枯黄期提前,生长季长度缩短。③影响矮嵩草返青的关键时期为每年的1月和3—4月,1月温度升高影响植物休眠进程进而延迟返青,而3—4月温度升高有利于热量积累使返青提前;影响矮嵩草枯黄的关键时期为7月上中旬和8月,期间温度升高使枯黄期提前。④根据PLS分析和相关分析,最低温度在各关键时期内显著影响植物物候,而最高温度仅在8月对枯黄期影响通过显著性检验,因此最低温度是影响高寒草地矮嵩草物候期的关键因子。     

高山林线与气候变化关系研究进展

20世纪全球气候经历了异常的变化。20世纪是过去1000年中增暖最大的1个世纪,并且90年代是最暖的10年。作为两个生态系统的过渡地带,生态过渡带是监测全球变化的重要地点,而森林和苔原之间的高山林线是全球变化最为敏感的地点。从高山林线树木个体对气候变化的响应、气候变化下林线处树木的更新、林线格局变化以及高山林线与气候变化关系研究中所采用的研究方法等方面,综合论述了国内外的研究进展,最后提出了高山林线研究中需要注意的问题,并对今后的研究趋势作了展望。     

Reproductive and physiological responses to simulated climate warming for four subalpine species

* The carbon costs of reproduction were examined in four subalpine herbaceous plant species for which number and size of flowers respond differently under a long-term infrared warming experiment. * Instantaneous measurements of gas exchange and an integrative model were used to calculate whole-plant carbon budgets and reproductive effort (RE). * Of the two species for which flowering was reduced, only one (Delphinium nuttallianum) exhibited higher RE under warming. The other species (Erythronium grandiflorum) flowers earlier when freezing events under warming treatment could have damaged floral buds. Of the two species for which flowering rates were not reduced, one (Helianthella quinquenervis) had higher RE, while RE was unaffected for the other (Erigeron speciosus). Each of these different responses was the result of a different combination of changes in organ size and physiological rates in each of the species. * Results show that the magnitude and direction of responses to warming differ greatly among species. Such results demonstrate the importance of examining multiple species to understand the complex interactions among physiological and reproductive responses to climate change.     

Response of nitrogen cycling to simulated climate change: differential responses along a subalpine ecotone

In situ nitrogen (N) transformations and N availability were examined over a four‐year period in two soil microclimates (xeric and mesic) under a climate‐warming treatment in a subalpine meadow/sagebrush scrub ecotone. Experimental plots that spanned the two soil microclimates were exposed to an in situ infrared (IR) climate change manipulation at the Rocky Mountain Biological Laboratory, near Crested Butte, Colorado. Although the two microclimates did not differ significantly in their rates of N transformations in the absence of heating, they differed significantly in their response to increased IR. Under a simulated warming in the sagebrush‐dominated xeric microclimate, gross N mineralization rates doubled and immobilization rates increased by up to 60% over the first 2 years of the study but declined to predisturbance rates by the fourth year. This temporal pattern of gross mineralization rates correlated with a decline in SOM. Concurrently, rates of net mineralization rates in the heated plots were 60% higher than the controls after the first year. There were no differences in gross or net nitrification rates with heating in the xeric soils. In contrast to the xeric microclimate, there were no significant effects of heating on any N transformation rates in the mesic microclimate. The differing responses in N cycling rates of the two microclimate to the increased IR is most certainly the result of differences in initial soil moisture conditions and vegetation type and cover.     

Idiosyncratic species effects confound size-based predictions of responses to climate change

Understanding and predicting the consequences of warming for complex ecosystems and indeed individual species remains a major ecological challenge. Here, we investigated the effect of increased seawater temperatures on the metabolic and consumption rates of five distinct marine species. The experimental species reflected different trophic positions within a typical benthic East Atlantic food web, and included a herbivorous gastropod, a scavenging decapod, a predatory echinoderm, a decapod and a benthic-feeding fish. We examined the metabolism–body mass and consumption–body mass scaling for each species, and assessed changes in their consumption efficiencies. Our results indicate that body mass and temperature effects on metabolism were inconsistent across species and that some species were unable to meet metabolic demand at higher temperatures, thus highlighting the vulnerability of individual species to warming. While body size explains a large proportion of the variation in species'' physiological responses to warming, it is clear that idiosyncratic species responses, irrespective of body size, complicate predictions of population and ecosystem level response to future scenarios of climate change.     

Soil carbon storage under simulated climate change is mediated by plant functional type

The stability of soil organic matter (SOM) pools exposed to elevated CO₂ and warming has not been evaluated adequately in long‐term experiments and represents a substantial source of uncertainty in predicting ecosystem feedbacks to climate change. We conducted a 6‐year experiment combining free‐air CO₂ enrichment (FACE, 550 ppm) and warming (+2 °C) to evaluate changes in SOM accumulation in native Australian grassland. In this system, competitive interactions appear to favor C₄ over C₃ species under FACE and warming. We therefore investigated the role of plant functional type (FT) on biomass and SOM responses to the long‐term treatments by carefully sampling soil under patches of C₃‐ and C₄‐dominated vegetation. We used physical fractionation to quantify particulate organic matter (POM) and long‐term incubation to assess potential decomposition rates. Aboveground production of C₄ grasses increased in response to FACE, but total root biomass declined. Across treatments, C : N ratios were higher in leaves, roots and POM of C₄ vegetation. CO₂ and temperature treatments interacted with FT to influence SOM, and especially POM, such that soil carbon was increased by warming under C₄ vegetation, but not in combination with elevated CO₂. Potential decomposition rates increased in response to FACE and decreased with warming, possibly owing to treatment effects on soil moisture and microbial community composition. Decomposition was also inversely correlated with root N concentration, suggesting increased microbial demand for older, N‐rich SOM in treatments with low root N inputs. This research suggests that C₃–C₄ vegetation responses to future climate conditions will strongly influence SOM storage in temperate grasslands.     

Adaptation to host plants may prevent rapid insect responses to climate change

We must consider the role of multitrophic interactions when examining species' responses to climate change. Many plant species, particularly trees, are limited in their ability to shift their geographic ranges quickly under climate change. Consequently, for herbivorous insects, geographic mosaics of host plant specialization could prohibit range shifts and adaptation when insects become separated from suitable host plants. In this study, we examined larval growth and survival of an oak specialist butterfly (Erynnis propertius) on different oaks (Quercus spp.) that occur across its range to determine if individuals can switch host plants if they move into new areas under climate change. Individuals from Oregon and northern California, USA that feed on Q. garryana and Q. kelloggii in the field experienced increased mortality on Q. agrifolia, a southern species with low nutrient content. In contrast, populations from southern California that normally feed on Q. agrifolia performed well on Q. agrifolia and Q. garryana and poorly on the northern, high elevation Q. kelloggii. Therefore, colonization of southern E. propertius in higher elevations and some northern locales may be prohibited under climate change but latitudinal shifts to Q. garryana may be possible. Where shifts are precluded due to maladaptation to hosts, populations may not accrue warm‐adapted genotypes. Our study suggests that, when interacting species experience asynchronous range shifts, historical local adaptation may preclude populations from colonizing new locales under climate change.     

中国五味子分布范围及气候变化影响预测

结合文献资料、标本记录和实际调查绘制了中国五味子分布图,并基于五味子分布范围和21个环境因子,运用Maxent软件预测了IPCC A2和A1B两种气候变化情景下21世纪50和80年代中国五味子分布范围.结果表明:五味子分布于中国15省/市(区),涉及151个县,随着纬度和经度的降低,面积逐渐减少,黑龙江、辽宁、内蒙古和吉林4省(区)是五味子主要分布区域;五味子在中国的潜在分布面积为145.12×104 km2,较好生境面积占48.6％,主要分布在长白山山脉、大兴安岭、小兴安岭以及河北省与辽宁省相邻区域;最佳生境面积仅占0.3％,主要分布在辽宁省的宽甸满族自治县、本溪满族自治县、桓仁满族自治县以及吉林省的安图县、和龙市和内蒙古自治区牙克石市.在A1B和A2两种情景下,未来五味子潜在分布区逐渐减少,A2情景的五味子潜在分布区下降比率大于AIB情景;至21世纪50年代,A1B和A2情景下五味子潜在分布区将缩减为当前潜在分布区面积的84.0％和81.5％;至21世纪80年代,A2情景下五味子潜在分布区仅为当前的0.5％,B2情景下五味子潜在分布区减至当前的1/2.     

高寒草甸退化对短穗兔耳草克隆生长特征的影响

以调查统计和比较样地法研究了江河源区高寒草甸退化对典型匍匐茎植物短穗兔耳草克隆生长特征的影响。结果表明,退化草甸的植物群落结构、功能以及土壤特征发生了明显地变化,继而对短穗兔耳草无性系的克隆生长行为和形态特性产生了影响。高寒草甸退化后短穗兔耳草的匍匐茎有所增多,分支强度加大。退化草甸内短穗兔耳草的基株高度小于未退化草甸,根长大于未退化草甸,基株的叶片数目间没有明显差别。退化草甸内短穗兔耳草的分株高度显著小于未退化草甸,分株叶数明显多于未退化草甸,而根长尽管大于未退化草甸,但差异不显著。短穗兔耳草匍匐茎长度在未退化草甸内明显大于退化草甸,匍匐茎茎生叶数和匍匐茎粗度也在未退化草甸大于退化草甸。短穗兔耳草在未退化草甸用于克隆繁殖的能量投资比例高于退化草甸,其中未退化草甸内短穗兔耳草基株的干重比例略低于退化草甸,分株和匍匐茎的干重比例高于退化草甸。高寒草甸退化对短穗兔耳草克隆生长特征的这些影响,是其对高寒草甸退化导致的资源和生境差异的反应,也是对资源利用达到的最合理状态,是一种选择适应的结果。     

西天目山针叶树直径生长与气候变化的关系

利用树木年轮分析方法研究了西天目山的三种主要针叶树：柳杉、金钱松和黄山松在林分范围内的直径生长与气候因子的关系。用逐步回归分析建立生长指数与１３个气候因子的回归方程,然后将生长曲线加入回归方程获得估计胸高处直径生长量的模型。结果表明,显著影响柳杉直径生长指数的因素为前期生长和夏季气温;影响金钱松生长指数达显著水平的有前期生长和夏、秋两季降水量;显著影响黄山松生长指数的因素有前期生长、夏季气温和秋季降水量。如果未来气温比目前分别升高１℃、２℃和３℃,柳杉的直径生长量将增加３．２％、６．３％和１１．１％;金钱松的将增加３．７％、５．６％和７．４％;黄山松的将增加３．５％、７．１％和１１．８％。文中对影响直径生长的其他因素也进行了讨论。