潢川金桂夏季光合特性分析

采用Li-6400XT便携式光合作用测定仪对潢川金桂成年树光合特性进行研究。结果表明:夏季潢川金桂净光合速率日变化呈明显的双峰型,最高峰出现在9:00,其净光合速率为10.05μmol/(m~2·s),次高峰出现13:00,其净光合速率为8.980μmol/(m~2·s),有明显的光合午休现象。根据光响应曲线可以得出潢川金桂的光饱和点(LSP)为1290μmol/(m~2·s),光补偿点(LCP)为74.21μmol/(m~2·s),表观光量子效率为0.0267,由CO_2响应曲线可以得出CO_2饱和点(CSP)为530μmol/mol,CO_2补偿点为61.24μmol/mol,羧化效率为0.0433。潢川金桂具有较高的CO_2补偿点和光饱和点说明潢川金桂是喜光的阳性植物。     

3年生观光木夏季的光合生理特性初探

以盆栽3年生观光木为试材,利用便携式光合作用测量系统、叶绿素荧光仪及叶圆片氧电极等在夏季对其气体交换特性、叶绿素荧光参数及离体叶片的光合放氧等进行了测定.结果表明,3年生观光木幼树叶片的光补偿点为10.1μmo L/(m~2·s),光饱和点约为为800μmol/(m~2·s),CO_2补偿点为50.72μmol/mol,CO_2饱和点为1 200μmol/mol.夏季晴好天气下,观光木净光合速率(Pn)的日变化曲线呈双峰型,第1个峰出现在08:00,Pn为9.0μmol/(m~2·s),第2个峰出现在16:00,Pn为4.6μmol/(m~2·s),12:00有明显的光合午休现象.在光合有效辐射较高的时段(10:00至14:00),观光木的F_v/F——m(PSⅡphotochemical efficiency)和PSⅡ实际光化学效率(ΦPSⅡ)均处于低水平,表明PSⅡ活性明显下降.     

羊草在多云条件下光合及水分生理生态特征研究

使用Li-6400便携式光合测定仪,对自然条件下呼伦贝尔草原羊草的光合及水分生理生态特征进行了研究,结果表明:八月的呼伦贝尔草原多阴云天气,羊草的净光合速率日变化呈现双峰曲线,蒸腾速率曲线与净光合速率表现出一致的趋势.光响应曲线、CO_2响应曲线结果表明:光合速率(P_n)与CO_2浓度(C_(CO_2))之间回归方程为P_n=-0.09051+0.03865 C_(CO_2)-1×10~(-5) C_(CO_2)~2,根据回归方程可求得CO_2补偿点为2.34μmol·m~(-2)·s~(-1),CO_2饱和点为1932.5μmol·m~(-2)·s~(-1).P_n与光合有效辐射(PAR)之间回归方程为P_n=-2.0596+0.02094 PAR-8×10~(-6) PAR2,光补偿点(LCP)为102.36μmol·m~(-2)·s~(-1),光饱和点(LSP)为1308.75μmol·m~(-2)·s~(-1),羊草较高的光补偿点和光饱和点是其适应内蒙古高原高光强环境的表现,也是其成为该地区优势植物的适应对策.     

4种忍冬属植物光响应特性

以紫花忍冬(Lonicera maximowiczii Regel)、早花忍冬(Lonicera praeflorens Batalin)、长白忍冬(Lonicera rupr-echtiana Regel)、金银忍冬(Lonicera maackii Maxim.) 4种忍冬为研究对象,测量光合生理指标,分析净光合速率(Pn)、胞间CO2浓度(Ci)、气孔导度(Cond)、蒸腾速率(Tr)对光合有效辐射(PAR)的响应.结果显示:4种忍冬属植物都属喜光植物,Pn的最大值出现在光合有效辐射为1 800～2 000μmol/(m~2·s)区间,分别为紫花忍冬20.6207μmol/(m~2·s),长白忍冬10.955 0μmol/(m~2·s),金银忍冬7.766 0μmol/(m~2·s),早花忍冬6.884 7μmol/(m~2·s).其中,紫花忍冬的净光合速率明显高于其他3种忍冬;在0～2 000μmol/(m~2·s)区间,Ci整体水平随PAR的增大呈下降趋势;随着PAR的增大,金银忍冬和早花忍冬的Cond呈增大、降低、增大的趋势,长白忍冬呈增大趋势,但幅度较缓慢,紫花忍冬呈先增大后降低的趋势;随光PAR的增强,4种忍冬属植物的Tr增大,其中紫花忍冬的增幅较大.     

水位梯度对狭叶香蒲光合作用的影响

水淹深度的变化影响着湿地植物的生长,然而长江中游作为暴雨频繁发生区域,暴雨事件可能对长江中游湿地碳汇功能产生重要影响.本实验以盆栽方法研究不同水位条件下香蒲植物叶片光合-光响应曲线的敏感度变化,以期揭示暴雨事件对湿地碳汇功能的影响规律.研究结果表明:水位为5 cm、10 cm和20 cm的狭叶香蒲植物叶片光合-光响应曲线发生了变化,出现水位越低光合能力越强,3种处理水平下,最大净光合速率依次为25. 430、14. 241和6. 886μmol/(m~2·s),光补偿点分别为18. 94、48. 32和27. 16μmol/(m~2·s),光饱和点各自为6 975. 50、1 963. 07和1 079. 77μmol/(m~2·s).植物叶片净光合速率与气孔导度、蒸腾速率和光合有效辐射呈正相关关系.     

烯效唑处理的玉米吐丝期穗位叶光合速率对不同气象条件的响应

烯效唑处理的玉米对光强、CO_2及空气湿度的响应研究表明,吐丝期雅玉2号和成单202穗位叶净光合速率(P_n)在光合有效辐射(PAR)小于600μmol/(m~2·s)时均随PAR升高而增加,大于700μmol/ (m~2·s)时均随PAR升高而减小.两个品种的P_n都随CO_2浓度增加而增加,CO_2浓度小于200μmol/mol时增加迅速,大于700μmol/mol时增加缓慢;两个品种的P_n随空气湿度增加呈先增后降趋势,当相对湿度低于68%时增加,高于68%时降低.     

温室屋面光伏组件对温室微环境及作物净光合速率的影响——以草莓温室为例

以"京藏香"草莓为实验作物,研究温室南面屋面安装光伏组件对温室微环境以及草莓叶片净光合速率的影响.结果表明:光伏温室内太阳辐射日均值相比普通温室降低了47.3%,光合有效辐射PAR降低了68%.光伏温室草莓叶片净光合速率P_n日均值为3.53μmol·m~(-2)·s~(-1),高于普通温室内草莓叶片P_n日均值3.34μmol·m~(-2)·s~(-1).在普通温室中,草莓叶片光能利用率(LUE)仅为光伏温室的26.3%,但草莓叶片净光合速率随空气温度、空气湿度和PAR变化的幅度均高于光伏温室.     

松嫩草原碱化草甸朝鲜碱茅光合生理生态特性的研究

在松嫩平原碱化草甸生长季中期,朝鲜碱茅不同龄级叶片净光合速率的日变化均为双峰曲线,第一个峰值出现在12:00左右,第二峰值出现在17:00左右;各龄级叶片中以4 a叶片的净光合速率最高,5 a叶片次之,3 a叶片最低.朝鲜碱茅为C3植物,光补偿点为56 μmol/ (m2·s),光饱和点为1 800 μmol/ (m2 ·s),光半饱和点为600 μmol/ (m2·s),光近饱和点为1 500 μmol/ (m2·s).     

花楸幼苗光合特性及其影响因子分析

使用Li-6400光合测定系统研究了生态因子对花楸(Sorbus pohuashanensisHedl.)二年生幼苗叶片的光合生理特性的影响.结果表明:花楸幼苗净光合速率日变化曲线均呈单峰型,无午休现象,且峰值(18.7μmol/(m2.s))出现在12:00,净光合速率的变化是由非气孔因素决定的;花楸光合作用受多因子交互作用的影响,交互作用对净光合速率的影响大于单一因子,其中光合有效辐射对净光合速率的影响最大;正常大气条件下,花楸幼苗叶片光饱和点为1 268.4μmol/(m2.s)、补偿点为31.9μmol/(m2.s),CO2饱和点为998.82μmol/mol、CO2补偿点为51.87μmol/mol.     

牡丹品种首案红与白玉的光合特性比较研究

自然条件下,以三倍体牡丹品种首案红和二倍体品种白玉为实验材料,测定叶片的光合日变化和光响应,结果表明:二者的净光合速率的日进程均为双峰型曲线,首案红一天当中的平均净光合速率、光饱和点和光补偿点均大于白玉,同时光饱和点的最大光合速率首案红12.39μmol/(m2.s)高于白玉6.28μmol/(m2.s)。该研究从光合生理角度显示,首案红比二倍体白玉具有较强的光合能力。     

科尔沁沙地放牧干扰恢复过程中植被组成和生物结皮微生物数量的变化

通过对科尔沁沙地禁牧10年后自然恢复状况的调查和实验分析,得出以下结论:(1)不同放牧强度自然恢复过程中,样地维管植物明显呈现出由一年生植物组成向多年生植物组成过渡的特点,盖度表现为轻牧恢复区(L)、中牧恢复区(M)、重牧恢复区(H)的盖度显著高于对照恢复区(C)、未围封放牧区(N)(P＜0.05);各处理样地生物结皮中苔藓植物和藻类植物的组成变化不大,但盖度表现为:苔藓结皮 L＞M＞H＞C＞N 区,藻结皮C＞H＞M＞L＞N区.(2)围封各恢复区(L、M、H)和未围封放牧区(N)藓结皮的含水量、结皮厚度及有机质含量方面显著高于藻结皮的(P＜0.05),而pH值却低于藻结皮的.(3)围封各恢复区微生物的数量显著高于未围封放牧区的(P＜0.05),在围封各恢复区内不论是藻结皮还是藓结皮,细菌、自身固氮菌和放线菌的数量在中度放牧恢复区数值最大,重度放牧恢复区的数量最少,两者差异达到显著水平(P＜0.05).(4)藻结皮、藓结皮微生物数量都随土壤深度的增加而呈降低的趋势,0～3 cm层的与3～5、5～10、10～20 cm三层的有显著差异(P＜0.05),藓结皮层及下层土壤微生物的数量要明显高于藻结皮层及下层土壤的.     

Cementing mechanism of algal crusts from desert area

34-, 17-, 4-, 1.5-year old natural algal crusts were collected from Shapotou Scientific Station of the Chinese Academy of Sciences, 40-day old field and greenhouse artificial algal crusts were in situ developed in the same sandy soil and the same place (37°27′N, 104°57′E). Their different cohesions both against wind force and pressure were measured respectively by a sandy wind-tunnel experiment and a penetrometer. On the basis of these algal crusts, the cementing mechanism was revealed from many subjects and different levels. The results showed that in the indoor artificial crusts with the weakest cohesion bunchy algal filaments were distributed in the surface of the crusts, produced few extracellular polymers (EPS), the binding capacity of the crusts just accomplished by mechanical bundle of algal filaments. For field crusts, most filaments grew toward the deeper layers of algal crusts, secreted much more EPS, and when organic matter content was more than 2.4 times of chlorophyll a, overmuch organic matter (primarily is EPS) began to gather onto the surface of the crusts and formed an organic layer in the relatively lower micro-area, and this made the crust cohesion increase 2.5 times. When the organic layer adsorbed and intercepted amounts of dusts, soil particles and sand grains scattered down from wind, it changed gradually into an inorganic layer in which inorganic matter dominated, and this made the crusts cohesion further enhanced 2–6 times. For crust-building species Microcoleus vaginatus, 88.5% of EPS were the acidic components, 78% were the acidic proteglycan of 380 kD. The uronic acid content accounted for 8% of proteglycan, and their free carboxyls were important sites of binding with metal cations from surrounding matrix.     

Ecological and environmental explanation of microbiotic crusts on sand dune scales in the Gurbantonggut Desert, Xinjiang

Results obtained from the field investigation and the analysis in laboratory show that many species of microbiotic crusts of lichens, mosses and algae develop extensively in the Gurbantonggut Desert, Xinjiang. The formation, species and distribution are closely related to the environmental conditions at the different positions of sand dunes. The animalcule crusts develop mainly on the mobile or semi-mobile sand surface of dune tops, the alga crusts develop mainly at the upper to middle parts of dune slopes, the lichen crusts develop at middle and lower parts of dune slopes, and the moss crusts are mainly distributed at the lower part of dune slopes and the interdune lowlands. The species, thickness and developing degree of microbiotic crusts increase from the upper part to the middle and lower parts of dune slopes and the interdune lowlands, and an obvious contrast between the microbiotic crusts and the different species of plant communities forms. The development and differentiation of microbiotic crusts at the different positions of dunes are the ecological appearance and the natural selection of synthetic adaptability of the different microbiotic crust species to the local environmental conditions, and are closely related to the ecological conditions, such as the physiochemical properties of soils and stability of topsoil texture.     

毛乌素沙地南缘沙区不同类型地表水分特征曲线测定与分析

为探明不同类型地表(裸沙、浅灰色藻类结皮、黑褐色藻类结皮和藓类结皮)的持水性能,采用砂性漏斗法对毛乌素沙地南缘沙区不同类型地表表层[(0~5)cm]土壤水分特征曲线进行了测定;并用v-G模型进行拟合。结果表明:1不同类型地表持水性能有差异,持水性能由弱到强依次是裸沙、浅灰色藻类结皮、黑褐色藻类结皮和藓类结皮,不同类型生物结皮样地持水性能分别是裸沙的1.3、1.7和2倍,不同类型生物结皮的持水性随结皮的发育呈增加的趋势;2不同类型地表土壤水分特征曲线呈"S"型分布,不同类型地表吸湿过程较脱湿过程具有显著的滞后性;3用v-G模型对测定结果进行拟合,拟合系数均小于0.009,拟合度高,表明该模型适用于此地区土壤,可用于模拟水分特征曲线;研究结果有助于全面了解生物结皮的水文效应,为受损系统的生态修复过程具有现实意义。     

Variation of the Fe/Mn ratio of ferromanganese crusts from the Central North Pacific: implication for paleoclimate changes

Hydrogeneticferromanganesecrusts(Fe Mn crustshereafter),areinorganiccolloidprecipitatesfromseawater,whicharebelievedtohaverecorded theevolutionofelementalandisotopiccompositionsof seawaterovertime[1—7].Studiesontraceelements andisotopeshavebroughtmoreinsightsthanstudies onironandmanganesecontents.TheMn/Feratio hasbeenconsideredtoreflectwaterdepth,deep wa teroxygenation[8,9],andhasalsobeensuggestedasa reliablecriterionfordistinguishingdifferentgenetic typesofferromanganesedeposits[10].Apossi…     

A deep seismic sounding profile across the Tianshan Mountains

The deep seismic sounding profile across the Tianshan Mountains revealed a two-layer crustal structure in the Tianshregion, namely the lower and upper crusts. Lateral variations of layer velocity and thickness are evidently shown. Low-velocity layers spread discontinuously at the bottom of the upper crust. The Moho depth is 47 km in the Kuytun area and 50 km in the Xayar area. In the Tianshan Mountains, the Moho becomes deeper with the maximum depth of 62 km around the boundary between the southern and northern Tianshan Mountains. The average velocity ranges from 6.1 to 6.3 km/s in the crust and 8.15 km/s at the top of the upper mantle. Two groups of reliable reflective seismic phases of the Moho (Pm1 and Pm2) are recognized on the shot record section of the Kuytun area. A staked and offset region, 20-30 km long, is displayed within a shot-geophone distance of 190-210 km in Pm1 and Pm2. Calculation shows that the Moho is offset by 10 km in the northern Tianshan region, 62 km deep in the south while 52 km deep in the north, and plunges northwards. In comparison with typical collisional orogenic belts, the structure of the Moho beneath the Tianshan Mountains presents a similar pattern. This can be used to explain the subduction of the Tarim plate towards the Tianshan Mountains. This intracontinental subduction is considered the dynamic mechanism of the Cenozoic uplifting of the Tianshan Mountains. The discovery of seismic phases Pm1 and Pm2 serves as the seismological evidence for the northward subduction of the Tarim plate.     

鲜枣塑料袋贮藏技术的研究

用不同通气面积的塑料袋贮藏鲜枣，结果表明：襄汾圆枣通气面积为6.4cm^2/kg、蛤蟆枣为3.2cm^2/kg，能够防止二氧化碳伤害、乙醇的多量积累和果实的软化，本项研究为鲜枣的塑料袋贮藏提供了技术参数。     

抚仙湖流域植被景观格局分析

 采用3S技术及结合野外植被样地调查,定量分析抚仙湖流域植被景观结构及各植被景观要素组分在不同海拔、坡向和坡度上的空间分布规律.采用FRAGSTATS 3.3 软件,定量分析了抚仙湖流域10种植被景观类斑的空间分布特征.主要研究结果包括:①自然植被、人工植被、居民点和水体分别占研究区面积的31.74%、35.13%、1.84%和 31.30%;② 旱地集中分布在海拔2 100 m以下;自然植被中,云南松林分布在海拔较低的区域,而华山松林分布于海拔相对较高的区域;③ 针叶林和半湿润常绿阔叶林等森林植被在阳坡、半阳坡地段分布较阴坡、半阴坡少,而半湿润常绿阔叶灌丛和灌草丛在阳坡、半阳坡地段分布较多;④ 自然植被集中分布的坡度区间主要在2°~25°之间.     

阿尔泰山河谷林封育研究

通过对新疆阿尔泰山河谷林封育区与非封育区天然林进行植被调查,从林分结构、林下草本重要值特征和物种多样性等方面对封育效果进行了分析。结果表明：（1）在5 a的封育期内,对于阿尔泰山河谷天然林的整体状况没有明显影响;（2）封育区林下草本种类比非封育区多了10种,相对增加了77.5 %,草本层盖度提高了36.4 %,相对增加了124.8 %;（3）封育区林下草本层Patrick丰富度指数和Shannon Wiener多样性指数均高于非封育区,而Simpson优势度指数和Pielou均匀度指数则没有明显的差异。可以看出,通过封育措施阿尔泰山河谷天然林林下植被得到了明显恢复,同时要加强封育区的管理,并延长封育年限。     

快速城市化背景下上海崇明植被覆盖度景观格局分析

通过研究崇明植被覆盖度及其景观特征历时17年的动态变化,再现了城市化进程对自然景观的干扰过程以及生态环境质量的变化.用TM/ETM+遥感影像解译区域植被覆盖度并进行其等级结构的时空特征分析,结果表明：1989～2006年间,经济发展迅速的崇明,其植被系统经历了从严重破坏到逐步恢复的过程.1989～2001年间,崇明县乡镇区和农场区植被受到破坏都较为严重;2001～2006年间,这种趋势在乡镇区没有根本改变,但农场区在这一期间植被覆盖度增加,植被覆盖度的等级结构也获得改善,而这一过程对全县植被系统的恢复做出了积极的贡献.