Effect of imitated global warming on Δ<Superscript>13</Superscript>C values in seven plant species growing in tibet alpine meadows

Open-top chambers were used to estimate the possible effects of global warming on δ¹³C of seven plant species grown in alpine meadow ecosystem. The δ¹³C values of plant species were lower after long-term growth in open-top chambers. In the course of experiment, temperature significantly increased inside the chambers by 4°C. Plant species grown at a lower elevation above sea level had higher δ¹³C values as compared to those grown at a higher elevation. This was in accordance with the effect of open-top chamber on δ¹³C values in plants. Greater availability of CO₂ and lower water vapor pressure at higher temperature inside the chambers, as indicated by an increase in discrimination against ¹³CO₂, probably result in more negative δ¹³C values of plants because higher stomatal conductance increases availability of CO₂ and causes greater discrimination against ¹³CO₂. The plant species studied could be the indicator species for testing global warming by the change in carbon isotope ratios at the two growth temperatures. This text was submitted by the authors in English.     

Factors influencing the distribution of Subantarctic deep-sea benthic foraminifera,Campbell and Bounty Plateaux,New Zealand

We investigate the combination of environmental factors that influence the distribution patterns of benthic foraminiferal tests (> 63 μm) in a topographically varied region crossed by both the Subtropical and Subantarctic Fronts, south-east of New Zealand. Seafloor sample sites, extending from outer shelf (50 m) to abyssal (5000 m) depths, are bathed by five different water masses, and receive phytodetritus from Subtropical, Subantarctic and Circumpolar surface water masses. Eight mappable associations are recognised by Q-mode cluster analysis of the benthic foraminiferal census data. Similar associations are identified using cluster analysis based solely on the presence or absence of species. Canonical correspondence analysis and a correlation coefficient matrix were used to relate the faunal data to a set of environmental proxies. These show that factors related to water depth (especially decreasing food supply with increasing depth) are the most significant in determining the overall foraminiferal distribution. Other contributing factors include surface water productivity and its seasonality; bottom water ventilation; energetic state of the benthic boundary layer and resulting substrate texture; and bottom water carbonate corrosiveness. Three shallow-water associations (50–700 m), dominated by Cassidulina carinata, Trifarina angulosa, Globocassidulina canalisuturata, Gavelinopsis praegeri, and Bolivina robusta, occur in coarse substrates on the continental shelf, and on the crests and upper slopes of four seamounts under well-oxygenated, high energy regimes, and high food input. Three mid bathyal to upper abyssal associations (500–3300 m), dominated by Alabaminella weddellensis, C. carinata, and Epistominella exigua, occur in biopelagic sandy mud, beneath a region of strongly seasonal food supply, with their composition influenced by total food flux, ventilation (Oxygen Minimum Zone), and bottom current strength. An unusual lower bathyal association (1200–2100 m), dominated by T. angulosa and Ehrenbergina glabra, occurs in a belt of coarser sandy substrate that runs along the crest of the submarine plateaux slopes beneath the strongly-flowing Subantarctic Front-related currents. A deep abyssal association (3500–5000 m), dominated by Nuttallides umbonifer and Globocassidulina subglobosa, occurs on the abyssal plain beneath oligotrophic lower Circumpolar Water south-east of the Subantarctic Front and is strongly influenced by the cold, carbonate-corrosive conditions.     

不同海拔高原鼠兔个性特征与SERT基因多态性关联

个性特征是指动物个体间稳定、可遗传的行为差异,与相关基因多态性有关,反映了动物对环境的适应模式,探究个性相关基因变异,将有助于更好地理解动物对环境的适应与进化机制。本文以高原鼠兔 (Ochotona curzoniae) 为对象,研究了5个不同海拔地区高原鼠兔的个性 (探究性、勇敢性和温顺性) 差异特征,并检测了个性相关基因5-羟色胺转运体 (SERT) 的单核苷酸多态性 (SNP) 和mRNA表达。结果发现,高海拔地区高原鼠兔的探究性和勇敢性显著高于低海拔地区,而高海拔地区高原鼠兔SERT基因mRNA表达量显著低于低海拔地区,提示不同海拔高原鼠兔个性特征差异可能与SERT基因mRNA表达有所关联。进一步检测不同海拔地区高原鼠兔SERT基因多态性及其分布差异情况,发现该基因存在6个SNP (其中5个位于外显子3,1个位于外显子5 );不同海拔地区鼠兔基因分布差异分析显示外显子5的c.A1063C 同义突变与海拔之间存在显著相关,高海拔地区该位点CC基因型分布频率显著高于低海拔地区;c.A1063C的基因型虽然与探究性、勇敢性无显著相关,但与温顺性显著相关。综上所述,随着海拔升高,高原鼠兔探究性和勇敢性增加,这有利于动物获取更多的食物资源,进而增加其生存机会。与此同时,SERT基因多态性显示与不同海拔地区的生存环境相适应的特征,且与温顺性有关,暗示不同海拔高原鼠兔个性差异可能与SERT基因SNP的差异有关。本研究从基因表达与突变的角度尝试阐述高原鼠兔适应不同海拔环境的行为差异,显示了不同海拔地区高原鼠兔行为生存策略潜在的分子机制。     

MTNR1a和MTNR1b基因在繁殖期与非繁殖期雄性高原鼢鼠HPG轴上的表达

高原鼢鼠 (Eospalax baileyi) 终年营地下生活,感光受洞道限制,但褪黑素 (Melatonin) 分泌水平仍存有季节差异,为探明褪黑素对高原鼢鼠季节性繁殖的调控作用,研究利用q?PCR技术检测雄性高原鼢鼠繁殖期 (5月) 和非繁殖期 (9月) 下丘脑、垂体及睾丸中褪黑素受体1a (Melatonin receptor 1a, MTNR1a) 和褪黑素受体1b (Melatonin receptor 1b, MTNR1b) 基因mRNA的相对表达量,通过免疫组织化学技术对MTNR1a和MTNR1b在睾丸中定位,并采用Image Pro Plus软件进行免疫组化阳性评价。结果发现,高原鼢鼠繁殖期下丘脑和垂体中MTNR1a基因的相对表达量显著高于非繁殖期的相对表达量 (P < 0.05),MTNR1b基因的相对表达量在不同时期无显著差异 (P > 0.05),但非繁殖期睾丸中MTNR1a和MTNR1b基因的相对表达量均显著高于繁殖期 (P < 0.01);繁殖期除长形精子外的所有类型细胞以及非繁殖期的间质细胞、支持细胞和精原细胞中均观察到MTNR1a的阳性信号,繁殖期除精原细胞和长形精子细胞外的所有类型细胞,以及非繁殖期间质细胞和支持细胞中均观察到MTNR1b的阳性信号,且非繁殖期MTNR1a和MTNR1b的平均光密度值均显著高于繁殖期 (P < 0.01)。MTNR1a和MTNR1b基因在雄性高原鼢鼠HPG轴上的表达模式,提示了褪黑素在其季节性繁殖调控中的潜在作用。     

放牧干扰下高原鼢鼠栖息地选择因素

以祁连山东段高寒草甸栖息的高原鼢鼠(Myospalax baileyi)为研究对象,探讨放牧干扰下高原鼢鼠适合栖息地选择的影响因素,为合理控制草原鼠害和保护生物多样性提供科学依据。在5个不同放牧强度小区中,连续3年监测高原鼢鼠相对种群密度变化,同时获取植被和土壤的变化数据。分析高原鼢鼠相对种群密度、植被(盖度、高度、频度、植被生物量、植被均匀度、丰富度、多样性和地下根系生物量)和土壤(紧实度、容重、水分)之间的关系。中度放牧干扰下,高原鼢鼠相对种群密度最低,不利于对栖息地的选择,轻度、次轻度放牧区的高原鼢鼠相对种群密度高于重度、次重度放牧区的;轻度放牧干扰的草地有利于高原鼢鼠种群数量的增加。高原鼢鼠相对种群密度与土壤紧实度、容重呈显著负相关(R=﹣0.921、﹣0.883,P0.05);与土壤水分呈显著正相关(R=0.879,P0.05);高原鼢鼠相对种群密度与地下根系生物量呈极显著正相关(R=0.982,P0.01),与植被丰富度呈显著正相关(R=0.921,P0.05),与地上植被总盖度呈显著正相关(R=0.909,P0.05),与地上生物量、均匀度、多样性呈不显著正相关(P0.05)。在草地放牧干扰系统中,非生物因素土壤紧实度、水分可能是高原鼢鼠栖息地选择的首要选择因素,食物资源也许是次要选择因素。     

西藏昌都发现白鹭

<正>2013年9月至2014年6月,笔者在西藏昌都市八宿县、贡觉县、芒康县和昌都县先后观察并拍摄到白鹭(Egretta garzetta),为西藏首次发现。2013年9月29日,在八宿县然乌镇政府后方的湖边(29°30′17.28″N,96°45′25.44″E,海拔3 934 m),观察到2只白鹭成鸟,其体形纤瘦,全身羽毛白色,头部无羽冠,肩、背和前胸的蓑状羽也消失,呈冬羽特征;虹膜为黄色;眼先黄绿;嘴黑色,但嘴裂处及下嘴基部显淡黄色;胫与跗跖部黑色,趾黄绿色。2014年5月至6月,     

林隙干扰和升温对小兴安岭红松和臭冷杉径向生长的影响

通过建立小兴安岭阔叶红松(Pinus koraiensis)林内林隙与非林隙红松、臭冷杉(Abies nephrolepis)轮宽年表,分析林隙干扰(微环境差异)和1980年后显著升温对树木径向生长的影响。结果表明:升温减缓了非林隙红松生长,却加快了林隙红松生长;升温后,非林隙红松受温度影响减弱,而林隙红松则增强,林隙和非林隙红松径向生长与帕默尔干旱指数(Palmer drought severity index,PDSI)均由负相关变为正相关;林隙干扰导致臭冷杉径向生长减缓,升温导致林隙与非林隙臭冷杉年生长量均下降了约50%,非林隙木对温度的负响应要高于林隙木;升温后,5—10月温度对非林隙木抑制作用明显,非生长季(1—5月)降水对非林隙臭冷杉的抑制作用加强,而对林隙臭冷杉则由抑制变为促进;PDSI与非林隙臭冷杉由升温前的负相关变为升温后的正相关,而林隙臭冷杉则负相关更显著;林隙干扰减少耐荫喜湿树木径向生长,而对阳性树种影响不大或略有增加;林隙木比非林隙木更易受外界环境变化的影响,林隙干扰可使喜湿耐荫树种提前适应暖干环境,以提高了对升温适应性;升温导致林隙木与非林隙木年轮气候响应差异变大。     

丛枝菌根真菌对茄子黄萎病的防治效果和茄子植株生长的影响

研究了接种丛枝菌根真菌(AMF)对茄子生长和对黄萎病的影响,并且探讨了AMF诱导植物抗病性的生理生化变化。结果表明:接种AMF能促进茄子的生长,明显降低茄子黄萎病的发病率和发病指数;与只接黄萎菌处理比较,在先接种AMF然后接种黄萎病原菌的情况下,可以降低茄子叶内脯氨酸含量和相对电导率,提高根系活力,提高过氧化物酶(POD)、多酚氧化酶(PPO)和苯丙氨酸解氨酶(PAL)的活性。试验显示,AMF对茄子黄萎病具有一定的生防效果。这种抗性可能来源于AMF提高了茄子营养水平,激活了植物抗病机制。     

黄土高原农牧交错带稀疏自然植被生态系统的地表能量特征

基于2011-2012年黄土高原农牧交错带稀疏自然植被生态系统的地表能量通量以及气象数据,对该地区能量平衡各分量(净辐射、感热、潜热和土壤热通量)以及波文比进行日、季节动态的特征分析,研究了潜热通量和感热通量对不同强度降雨事件响应程度的差异,并分析了潜热通量和感热通量的主控因子.结果表明:该地区净辐射、感热、潜热和土壤热通量的日、季节动态曲线均为单峰型曲线,净辐射、感热通量、潜热通量和土壤热通量的年平均值分别为78.19、33.32、24.91和2.65 W·m-2.在全年能量收支平衡中,感热通量占净辐射的43％,潜热通量占32％,土壤热通量占3％,表明对于黄土高原农牧交错带自然稀疏灌木生态系统,全年能量主要以感热的形式交换.生长季感热和潜热占净辐射的比例相同(36％);而在非生长季,感热占主导,占净辐射的比例高达54％.潜热通量在强、弱降雨事件发生后明显升高,感热通量则明显下降.潜热通量与净辐射、水汽压差及植被参数均显著相关,感热通量与净辐射及空气温度梯度显著相关.