人工-天然杉阔混交林种群生态位及竞争研究

对人工 -天然杉阔混交林中 4个主要种群进行生态位研究 ,定量测定混交林中主要种群生态位宽度、生态位相似比例、生态位重叠 ,并分析了各种群生态位的生态学意义 ;同时采用Lotka_Volterra竞争方程研究混交林中主要种群。结果表明 :通过定量的生态位分析 ,结果与自然规律相符合。平衡时 ,杉木和米槠相对优势度分别为87 4 5 %和 12 5 5 % ,即人工 -天然杉阔混交林仍将由杉木、米槠两种种群共优组成 ,杉木种群支配整个群落。     

物种或种群生态位宽度与生态位重叠的计测模型

提出生态位宽度和生态位重叠的新定义及其若干测度模型.对不同学者提出的许多测度生态位宽度和生态位重叠的模型进行分析和评述.迄今为止,在国内限于单一生态资源轴上的生态位参数计测研究很多,随着多维生态位计测方法的不断发展,物种或种群在多维生态空间内的生态位宽度和生态位重叠计测,将备受关注.     

Impact of soil engineering by two contrasting species of earthworms on their dispersal rates

By burrowing galleries and producing casts, earthworms are constantly changing the structure and properties of the soils in which they are living. These changes modify the costs and benefits for earthworms to stay in the environment they modify. In this paper, we measured experimentally how dispersal behaviour of endogeic and anecic earthworms responds to the cumulative changes they made in soil characteristics. The influence of earthworm activities on dispersal was studied in standardised mesocosms by comparing the influence of soils modified or not modified by earthworm activities on earthworm dispersal rates.The cumulative use of the soil by the earthworms strongly modified soil physical properties. The height of the soil decreased over time and the amount of aggregates smaller than 2 mm decreased in contrast to aggregates larger than 5 mm that increased. We found that: (i) earthworm activities significantly modified soil physical properties (such as bulk density, soil strength and soil aggregation) and decreased significantly the dispersal rates of the endogeic species, whatever the species that modified the soil; (ii) the decreasing in the dispersal proportion of the endogeic species suggests that the cost of engineering activities may be higher than the one of dispersal; (iii) the dispersal of the anecic species appeared to be not influenced by its own activities (intra-specific influences) or by the activities of the endogeic species (inter-specific influences). Overall these results suggest that the endogeic species is involved in a process of niche construction, which evolved jointly with its dispersal strategy.     

黄土丘陵区不同管理方式下草地优势种群的生态位

以吴起县杨青川流域草地为研究对象,对封育(Enclosure)、放牧(Grazing)、施肥(Fertilization)、刈割(Clipping)、灭鼠(Deratization)5种管理方式的草地群落进行调查,并运用Levins生态位宽度和Pianka生态位重叠指数对5种管理方式下主要植物种群生态位特征进行分析。结果表明,达乌里胡枝子(Lespedeza davurica)、铁杆蒿(Artemisia sacrorum)、赖草(Leymus secalinus)、猪毛蒿(Artemisia scoparia)和硬质早熟禾(Poa sphondylodes)的种群总生态位宽度较大,封育放牧施肥刈割灭鼠管理模式下,生态位宽度最大的分别是达乌里胡枝子、赖草、紫花地丁(Viola philippica)、达乌里胡枝子和猪毛蒿,生态位宽度值大于4的物种数分别为6、6、3、4和3种。不同管理方式下各种对间的重叠指数平均值由大到小依次封育放牧施肥刈割灭鼠。施肥管理中,种群间生态位宽度与生态位重叠之间存在线性关系,其它管理方式中种群生态位宽度与生态位重叠之间不存在线性关系。生态位分析表明,封育和放牧管理下种群间对资源的需求趋于相同,彼此间通过竞争共存,有利于群落演替,草地生态系统逐渐得到恢复,施肥、刈割、灭鼠管理使群落物种竞争排序发生变化,破坏了草地生态系统原有的竞争机制,导致群落向简单群落演替。从牧草发展角度出发,封育、施肥和刈割有利于优质牧草生长。     

回交高代选择导入系的纹枯病抗性与抗旱性的遗传重叠研究

利用来自抗旱性较好的供体亲本（BG300和BG304）、具有两种遗传背景（IR64和特青）的水稻高代回交（BC2）抗旱选择导入系，通过人工接种的方法鉴定纹枯病抗性，考察纹枯病抗性与抗旱性之间可能存在的遗传重叠。通过与受体亲本的纹枯病抗性表现比较发现，具有特青背景的抗旱选择导入系倾向于纹枯病抗性的降低，而IR64背景的抗旱选择导入系则倾向于纹枯病抗性的增强。基于基因型与表型的方差分析共鉴定到6个与纹枯病抗性相关的位点，其中QSbr6在不同供体和背景的两个群体中分别检测到，而QSbr10则在同一供体的两个遗传背景下均检测到；有3个位点（QSbr6、QSbr8和QSbr10）与同一群体中检测到的抗旱性位点位置相近，很可能是两种抗性重叠的遗传基础。尽管方差分析的方法在选择导入系的非选择目标性状相关位点的鉴定中存在相当程度的偏低估计，本研究所检测到的纹枯病抗性位点，特别是那些与抗旱性重叠位点的分子标记以及相关的抗性株系仍将为进一步的水稻纹枯病抗性和抗旱性的多抗性育种和深入的遗传重叠研究提供有用的信息和材料。     

京郊风景游憩林侧柏-刺槐群落林下植被生态位研究

对北京市郊区风景游憩林侧柏-刺槐群落林下植被的主要植物种群的生态位宽度、生态位相似比例和生态位重叠分析表明,求米草、荆条、孩儿拳头和细叶苔草生态位宽度值较大,上层林分主要树种侧柏和刺槐的林下更新苗生态位宽度比其他植物种林下更新苗的生态位宽度低;林下植物种群的生态位相似性比例值和生态位重叠值相对较小,不同种群间对资源的竞争相对不剧烈,可采取人工措施改善树种的配置,促进生态位分化。     

半干旱地区植被恢复过程中林下植被生态位特征的研究

应用生态位理论,以黄土半干旱区6个不同密度林分林下草本层植被为研究对象,以林分密度作为资源轴,以物种重要值为生态位计测的状态指标,对林下植被进行生态位计测和分析,揭示林内资源环境利用状况。结果表明:林下植被的生态位宽度值普遍较小,其中阿尔泰紫婉、铁杆蒿等生态位宽度较大,这与无林地相似,同时物种间生态位重叠并不普遍,重叠度普遍不大,各种对间对资源的共享趋势不明显,生态位发生分离,显示了林下植被状况差。     

Contrasting intraspecific dietary shifts in two terapontid assemblages from Australia’s wet‐dry tropics

Abstract – This study assessed the size‐related patterns of dietary resource use in terapontid assemblages from two north Australian wet‐dry tropical river systems exhibiting contrasting long‐term flow regimes. Substantially higher size‐related dietary divergence in the form of additional trophic guilds and lower levels of dietary overlap were evident among terapontids from the comparatively stable Daly River system, particularly during the dry season. Relatively restricted expression of size‐related dietary shifts in conjunction with higher levels of dietary overlap and no significant seasonal effects on dietary overlap were features of assemblage interaction in the highly variable Burdekin River. Results highlight size‐related dietary shifts as a complex aspect of terapontid trophic habits, and one that can exhibit considerable spatial dynamism.     

兰州引黄灌区玉米田杂草群落及生态位研究

对兰州引黄灌区玉米田杂草进行了研究,初步了解了其杂草种类和杂草种群的消长动态。主要杂草有打碗花、田旋花、藜、刺儿菜、荠菜、稗草、马齿苋、反枝苋、狗尾草。主要杂草的干重为藜、反枝苋、稗草分别列第1、第2和第3位。生态位的研究结果表明,藜的时间、水平、垂直生态位宽度值最高,分别为0.952 6,0.971 8,0.937 9,其危害最大;其次为反枝苋和稗草。藜、反枝苋和稗草为优势种群,与玉米存在时间、水平、垂直空间的竞争激烈,并且这3种杂草的生态位重叠值也最大,因此在使用一种除草剂时,可能会导致另两种杂草的发生与蔓延。马齿苋尽管数量最多,但其在垂直方位的生态位宽度值最小,对玉米影响小,处于劣势。除草处理各经济性状指标值均较不除草对照高,其折合产量为10 111.11 kg/hm2,较不除草处理增产36.19%。     

牛GM-CSF与金黄色葡萄球菌黏附素FnBPB共表达质粒的构建与原核表达

采用PCR方法对牛粒细胞-巨噬细胞集落刺激因子(GM-CSF)和金黄色葡萄球菌FnBPB的D区进行特异性的扩增,并通过重叠延伸PCR扩增GM-CSF-FnBPB串联基因,构建了克隆质粒pMD19-GM-CSF-FnBPB。利用表达载体pET-32a(+)对该融合基因片段进行原核表达,SDS-PAGE分析表明,在1mmol/L IPTG诱导浓度下,在39ku处出现了与目的蛋白一致的外源蛋白带,Western blot分析表明,该蛋白具有反应原性,进而证明该融合基因成功在原核细胞中表达。