Annual and seasonal variations of Q10 soil respiration in the sub-alpine forests of the Eastern Qinghai-Tibet Plateau, China

The annual and seasonal variations in the temperature sensitivity of soil respiration (Rs) were assessed through continuous measurements during the 2004-2006 growing seasons using chamber-based techniques in two sub-alpine forest ecosystems in the Eastern Qinghai-Tibet Plateau, China. The study sites were 40-year-old spruce plantations (Picea asperata) (FSPF) and Faxon Fir Primary Forest (FPF). Our results showed that Q_10, regardless of site origin, exhibited a strong seasonal and annual variation pattern, and decreased with soil temperature increase. Estimated Q₁₀ values ranged between 1.16 and 24.3. The maximum, annual, mean Q₁₀ values remained consistent over 3 years, while the highest Q₁₀ values (7.01 in FSPF and 6.39 in FPF) occurred in 2005 (for all sites). There was no significant difference observed among Q₁₀ values between the two forest types in each year (2004-2006) (p = 0.07). Q₁₀ values were fitted well with data of soil temperature using linear regression models, while the correlation between Q₁₀ and soil moisture was not significant (p > 0.1). This study suggested that soil temperature was the dominant factor influencing Q₁₀ values, while soil moisture was a potential contributor to the annual and seasonal variations of Q₁₀ in a sub-alpine forest. Due to the complexity of correlation between Rs and soil moisture, Q₁₀ values derived from annual and seasonal patterns of R_S should be used with caution when predicting future soil CO₂ emissions under conditions of global warming.     

近20年来江苏省冬小麦生育进程和产量对气候变暖的响应

为了解气候变暖对江苏省冬小麦生长发育与产量的影响,利用相关和回归等统计方法分析了该省有代表性的淮阴、扬州和昆山观测点1990-2009年冬小麦生长季的温度、降水量、产量及1992-2009年生育进程的变化。结果表明,三个观测点冬小麦生长季平均气温上升明显,上升速度分别为每年0.056、0.084和0.059℃,而降水量变化不明显。冬小麦生育期后十年比前十年分别缩短5、4和11 d,且表现为营养生长阶段缩短。去趋势后产量与气候因子关系分析表明,扬州和昆山小麦产量受最低温度影响最大,最低温度上升1℃,分别减产4.9%和5.9%。而淮阴小麦产量受最高温度影响最大,且表现出升温有利于增产。随平均温度上升,扬州、昆山分别减产3.2%和4.1%,淮阴增产1.7%。降水对三站点历年产量变化的影响不大。     

模拟增温和添加氮素对高寒草甸草地生产力影响的初步研究

为探索高寒草地植被对模拟增温和添加氮素的响应机制,通过在野外对高寒草甸进行模拟增温和硝态氮、铵态氮的氮素添加试验,研究模拟增温和添加氮素对高寒草地群落物种组成、生产力及土壤水含量的影响.结果表明:增温和添加氮素可显著增加植物地上总生物量、优良牧草地上生物量和植被平均高度(P <0.05).增温处理能增加植物种类,且有利于杂类草生物量的增加;对几种主要植物来说,增温施氮互作下植株高度高于其他处理,土壤0～15和15～30 cm水分均先减少后增加,且都为不增温不施肥处理最高.可见增温施氮互作处理能够促进植被的生长,但不利于土壤水分的增加.     

Development of chloroplast DNA markers in Japanese Imperata cylindrica

Imperata cylindrica (cogongrass) is one of the most invasive grass weeds found worldwide. In Japan, this grass grows as three climate types: cool temperate (CT), common (CM) and subtropical (ST). An early flowering (E) type has been also reported. Among them, the CM type is large and most invasive. Recent global warming may cause the extension of distribution of the CM type to northern parts of Japan and may allow hybrids to form between the CM and CT or E types. The hybrids sometimes show heterosis and this leads to new weed problems. Distinguishing between the hybrids and parents on a morphological basis is difficult. We investigated polymorphisms of eight cpDNAs to enable distinction between the ecotypes and the hybrids. Fourteen haplotypes were detected in 33 Japanese clones, based on variations in eight cpDNA regions. Based on three substitutions in the psbA–matK spacer, the ORF170 intron1, the trnL(UAA) intron–trnF(GAA) spacer and indels in the trnL(UAA) intron–trnF(GAA) spacer, the haplotypes were clustered into three phylogenetic groups: I, IIa and IIb, which corresponded with the CM and ST, E and CT types, respectively. The polymorphism in the cpDNA therefore enables us to distinguish among the ecotypes and is useful for prediction of the range expansion of the CM type.     

气候变暖对农业害虫及其天敌的影响

全球气候的持续变暖引起了人类的高度关注。农业害虫是关系到农业生产顺利进行的一个特殊的昆虫类群,已经受到温度升高的影响。本文从气候变暖对农业害虫的发生、为害以及与天敌间关系的影响等三方面进行了综述。温度升高导致农业害虫的发生区域扩张,发生期提前和延长,高温适生种群发生量增大;农业害虫的为害时期改变,为害程度加重,为害物种之间产生新的竞争关系;农业害虫与寄主植物、天敌之间的同步性发生改变,继而影响到农业害虫的生物防治。本文最后对当前的研究工作进行了评述,就气候变暖形势下农业害虫的防治提出建议。     

Influence of climate warming and nitrogen deposition on soil phosphorus composition and phosphorus availability in a temperate grassland,China

Climate warming and nitrogen(N)deposition change ecosystem processes,structure,and functioning whereas the phosphorus(P)composition and availability directly influence the ecosystem structure under conditions of N deposition.In our study,four treatments were designed,including a control,diurnal warming(DW),N deposition(ND),and combined warming and N deposition(WN).The effects of DW,ND,and WN on P composition were studied by31P nuclear magnetic resonance(31P NMR)spectroscopy in a temperate grassland region of China.The results showed that the N deposition decreased the soil pH and total N(TN)concentration but increased the soil Olsen-P concentration.The solution-state31P NMR analysis showed that the DW,ND and WN treatments slightly decreased the proportion of orthophosphate and increased that of the monoesters.An absence of myo-inositol phosphate in the DW,ND and WN treatments was observed compared with the control.Furthermore,the DW,ND and WN treatments significantly decreased the recovery of soil P in the NaOH–EDTA solution by17%–20%.The principal component analysis found that the soil pH was positively correlated with the P recovery in the NaOH–EDTA solution.Therefore,the decreased soil P recovery in the DW and ND treatments might be caused by an indirect influence on the soil pH.Additionally,the soil moisture content was the key factor limiting the available P.The positive correlation of total carbon(TC)and TN with the soil P composition indicated the influence of climate warming and N deposition on the biological processes in the soil P cycling.     

渭北旱塬区气温变化与冬小麦物候的响应

通过对渭北旱塬区永寿、风翔、蒲城、旬邑4个农业气象试验站1971年到2010年冬小麦观测数据以及30个县市区同期气象资料同步观测分析,得出渭北旱塬区气候近40年来增温明显,且以冬季和春季增温最为显著。受气候变化影响,本区域冬小麦播种期、越冬期推迟,返青期、拔节期、抽穗期、成熟期等发育期普遍提前,以返青期提前最为显著,相关性分析显示,除了冬前生长期,冬小麦越冬期以及春季各发育期间隔和发育期平均气温相关显著,而且春季的相关性明显比冬季显著,但表现在发育期间隔方面,却是冬小麦越冬期呈显著缩短趋势,而返青后各发育期间隔没有明显变化。结论认为：气候变暖一方面有利于越冬农作物安全越冬,减少冻害对农业生产的影响,而且温度升高,也增加了农业生产积温,使农作物可生长期延长,有利于提高复种指数;另一方面,由于旱塬区春季气温变率较大,发育期提前将导致作物受冻害的气候风险增大,尤其果树开花期遭受冻害,将对产量构成严重威胁。冬季气温持续上升,将导致冬小麦条锈病孢子和林果病虫害等安全越冬,对病虫害防治工作带来很大难度。因此,气候变暖对旱塬农业生产将产生深刻的影响,应引起高度关注。     

气候变暖对郑州黄河湿地鸟类分布的影响

2004年12月～2009年9月,对郑州黄河湿地自然保护区鸟类资源进行系统的调查,共记录到鸟类15目36科115种;郑州黄河湿地鸟类不断丰富,鸟类多样性呈上升趋势;部分东洋种鸟类的分布区向北扩散到郑州黄河湿地;部分鸟类的居留型发生变化。文献记录到的变化时间主要集中在1990年以后,与郑州地区（黄河中下游）气温的变化趋势相一致,与该地区气温上升,大气异常变暖呈正相关性。     

全球气候变暖对中国种植制度可能影响Ⅳ.未来气候变暖对东北三省春玉米种植北界的可能影响

【目的】在全球气候变化背景下,中国气温明显升高已成为共识,这一变化对中国农业生产尤其是对种植制度及作物布局的影响越来越受到农业生产管理部门和专家学者的重视。【方法】本文结合SRES的两种排放情景A2(强调经济发展)和B1(强调可持续发展)预估的未来气候数据,采用经验频率法计算不同保证率下的积温,探讨了未来气候情景下东北三省春玉米不同熟型品种种植北界的变化趋势,同时探讨了未来气候情景下研究区域内春玉米缺水率的变化趋势。【结果】未来气候情景下,在不考虑CO2浓度升高对作物生长发育影响的前提下,东北三省春玉米不同熟型品种种植北界不同程度向北移动,在界限敏感区域内中晚熟品种替代早熟品种,使得玉米生育期延长,干物质积累增加,可以提高东北三省春玉米产量。然而在未来21世纪中期,春玉米缺水率亦呈现增加的趋势,为种植界限北移带来一定的风险。【结论】在未来气候条件下,春玉米不同熟型品种种植北界北移需综合考虑热量和水分的影响,适区种植以减少由于干旱造成的春玉米减产。     

应对全球气候变化决不能忽视草原的重大作用

应对气候变化既要重视森林也要重视草原,草原植物对森林固碳起着促进和互补作用;草原不仅是生态型碳库,更是经济型、社会型碳库。应对气候变化,草原能够发挥特别重要的作用,其固碳能力决不容小视,碳成本相对低廉,固碳形式比较稳定,且能有效地发挥碳汇作用。草原是地球的温度调节器,发展草地农业,有利于减少农业生产中的碳排放。因此,我们应加强草原保护建设,提高应对气候变化水平;树立"大碳库"理念,重视森林也重视草原;加大政策和投入力度,不断增强碳库能力;强化草原依法管理,维护草原碳库稳定;积极利用有利的国际环境,大力发展草原碳汇;重视草原固碳研究,提高科技支撑水平;将"植树节"改为"绿化节",推动全民种草植绿。