云南蕊帽忍冬的扦插育苗方法研究

云南蕊帽忍冬(Lonicera pileata Oliv.f.yunnanensis(Fr.)Rehd)是分布于云南、四川等地海拔2100—3200米处的常绿或半常绿小灌木,现主要开发作为盆景材料和绿篱植物。本文研究了该植物的扦插育苗方法,结果表明,云南蕊帽忍冬的扦插育苗可全年进行,应利用当年抽生的木质化或半木质化枝顶段或中段作为插条,长5—6厘米,用IAA 2000ppm快蘸后插入滇池草炭或红土或炉渣中,在温度15-38℃,平均空气相对湿度87.9%以上,透光约50%全光照条件下,30—50天内可得到好的生根苗;芽和叶在云南蕊帽忍冬的扦插生根中起重要作用,采条时要避免它们的损坏和脱落,本文还对在6-8月份抽生枝最旺盛的期间,在昆明的露地进行了扦插育苗试验,认为露地扦插后,插床用白色塑料薄膜封闭,竹帘遮荫,插条生根最好。     

莫斯科州针阔混交林带森林群落的灌木层结构分析

本文通过分析莫斯科州针阔混交林带１０种类型的森林群落的灌木层结构,指出森林群落中灌木层的结构（垂直结构和水平结构）特点首先取决于组成该层次的灌木种的生物学特性,此外,在不同的群落中乔木层的郁闭度、群落内生境的不一致性（如土壤的水分和肥力状况的差异）以及幼木层的盖度等在不同的程度上影响着灌木的成层和结构。分析表明,灌木在不同的针阔混交林群落中的垂直分布可归纳为三种几何类型：金字塔式、菱形式和倒三角形式。灌木的水平配置多为集团分布或随机分布,趋于集团分布。     

Variation in Greek phrygana vegetation in relation to soil and climate

Abstract. Variation in species composition and community structure in nine Greek phrygana (dwarf-shrub) sites was related to soil and climate variables by using Canonical Correspondence Analysis. The distribution of the Greek phrygana communities appeared to be related to soil rather than to climate. It is postulated that human action has eliminated the original variability related to climate factors in western Greek ecosystems; as a result, phrygana communities in this part of Greece are the result of human impact.     

Cumulative effects of land use,altered fire regime and climate change on persistence of Ceanothus verrucosus,a rare,fire‐dependent plant species

Mediterranean ecosystems are among the highest in species richness and endemism globally and are also among the most sensitive to climate and land‐use change. Fire is an important driver of ecosystem processes in these systems; however, fire regimes have been substantially changed by human activities. Climate change is predicted to further alter fire regimes and species distributions, leading to habitat loss and threatening biodiversity. It is currently unknown what the population‐level effects of these landscape‐level changes will be. We linked a spatially explicit stochastic population model to dynamic bioclimate envelopes to investigate the effects of climate change, habitat loss and fragm entation and altered fire regime on population abundances of a long‐lived obligate seeding shrub, Ceanothus verrucosus, a rare endemic species of southern California. We tested a range of fire return intervals under the present and two future climate scenarios. We also assessed the impact of potential anthropogenic land‐use change by excluding land identified as developable by local governments. We found that the 35–50 year fire return interval resulted in the highest population abundances. Expected minimum population abundance (EMA) declined gradually as fire return interval increased, but declined dramatically for shorter fire intervals. Simulated future development resulted in a 33% decline in EMA, but relatively stable population trajectories over the time frame modeled. Relative changes in EMA for alternative fire intervals were similar for all climate and habitat loss scenarios, except under the more severe climate scenario which resulted in a change in the relative ranking of the fire scenarios. Our results show climate change to be the most serious threat facing obligate seeding shrubs embedded in urban landscapes, resulting in population decline and increased local extirpation, and that likely interactions with other threats increase risks to these species. Taking account of parameter uncertainty did not alter our conclusions.     

Effect of shrubs and seasonal variability of rainfall on the establishment of Aspidosperma quebracho‐blanco in two edaphically contrasting environments

Abstract Three experiments were conducted to verify if an increase in environmental stress level would affect the interactions between two species of nurse shrubs and seedlings of Aspidosperma quebracho‐blanco. This is a mesic species with a generalist distribution over an extensive environments gradient. The relationship between Larrea divaricata and seedlings of A. quebracho‐blanco was studied in two contrasting soils, a silty loam soil with higher surface clay content and a sandy loam soil. The effect of seasonal variability of rainfall on the initial establishment of seedlings under the shade of L. divaricata was evaluated in three consecutive years. The effect of nurse plant shade was tested comparing two shrub species with different types of leaf life span (sclerophyllous‐evergreen and leguminous‐deciduous). The natural establishment of A. quebracho‐blanco depended on shaded microsites, but not on the type of shade provided by different nurse shrubs. Emergence and initial establishment depended on interactions of soil type and seasonal rainfall variation with nurse plants. The importance of facilitation increased with clay soil (CS). Sandy soil was ‘less humid’ than CS under shrub shade. However, establishment success depends on opportune even rainfall distribution in interaction with nurse plant presence.     

3种荒漠灌木的用水策略及相关的叶片生理表现

以新疆古尔班通古特沙漠南缘原始盐生旱生荒漠的3种建群灌木多枝柽柳(Ｔamarix ramosissima)、梭梭(Ｈaloxylon ammodendron)和琵琶柴(Reaumuria soongorica)为对象,跟踪自然降雨过程,利用LI-6400光合作用系统和Model 3005植物水分压力审测定光合作用和叶水势的变化,以研究浅层土壤水分条件改变对荒漠灌木主要叶片生理特征的影响;并在原始生境中将植株根系完整地深挖取出,进行根系形态结构调查,以确定此3种灌木根系功能型与用水策略。当浅层土壤分别处在水分充足及匮缺的条件下时．测定3种灌木的光合作用响应曲线和日过程曲线．以及黎明前和止午叶水势,结果表明：浅层土壤水分状况变化时,3种灌木的光合能力均没有显著改变;多枝柽柳的叶水势亦没有明显波动;而梭梭和琵琶柴的叶水势却表现出显著差异。在两种功能型根中,多枝柽柳为深根型,生存和乍理活动的维持主要依赖于地下水;而梭梭和琵琶柴为非深根型植物,主要水源是降水形成的浅层土壤水,其用水策略是根据水分条件行效调节根系和冠层生长,从而维持正常的光合作用。即荒漠灌木在长期适应的过样中．已形成不同的根系功能型和用水策略;叶水势对浅层土壤水分状况变化的种间差异性响应在一定程度上反映了这一点。同时．此3种荒漠灌小通过不同的个体适应策略都能够实现水分平衡和碳收支的有效调节,这主要体现为浅层土壤水分条件变化时光合响应的种间一致性。     

The distribution of heath balds in the Great Smoky Mountains,North Carolina and Tennessee

Abstract. We used remote sensing and a geographic information system to model the distribution of evergreen shrub communities, called ‘heath balds’, in the Great Smoky Mountains, North Carolina and Tennessee, USA. The 421 heath balds averaged 1.8 ha in size and covered 0.3% of the landscape. They reached their greatest importance on upper slopes (92% had relative slope positions > 80), convex topography (82% occurred on sites with a curvature greater than 2.6), and elevations between 1100 and 1600 m (94% of the balds). Although heath balds were found in old‐growth watersheds, the two watersheds with the greatest number of balds burned extensively after logging in the early 1900s. Bald occurrence was positively correlated with burned sites, old growth condition, and a highly acidic rock type. Heath balds showed a striking geographic pattern, with 88.1% of the area of this community found in six watersheds comprising only 35.4% of the study area. Despite similar topography, geology, and history, the eleven other watersheds had only 11.9% of the bald area while comprising 64.4% of the study area. Multivariate models showed that this community occurs on only 0.4 to 9.0% of the seemingly appropriate sites. Once established, this shrub community, with its dense evergreen canopy and thick leaf litter, is resistant to tree invasion. Both forest and shrub communities are stable on sites that are seemingly ideal for heath bald occurrence.     

内蒙古草原植被覆盖度遥感估算

以内蒙古锡林浩特市南部中国科学院草原生态系统定位研究站周围的草场为研究对象, 分析比较了统计模型和亚像元分解模型进行草地植被覆盖度(vegetation coverage, VC)遥感估算的适用性。结果表明, 根据Landsat-5 TM影像数据计算的比值植被指数(simple ratio vegetation index, SR)与观测的VC的相关性最高(R² = 0.761); 统计模型和亚像元分解模型生成的VC空间分布特征相似, 但亚像元分解模型得到的VC平均值比统计模型的结果高0.091; 在VC的低值和高值区, 两种方法得到的VC结果相似; 但在VC的中值区, 亚像元模型得到的结果较统计模型的结果偏高。     

萌蘖调控对辽东栎留存萌生株生长与结实的影响

比较了不同调控措施对岷江上游辽东栎萌生灌丛生长与结实的影响.结果表明,人为调控对辽东栎萌生灌丛本生长阶段的高生长与有性繁殖有着显著影响.各调控措施对辽东栎灌丛萌生株的基径增长未产生明显影响;保留2支和3支萌生株的丛高生长优势明显.调控丛的新生枝数量、总长度、总生物量较未调控前有较大增加,保留2支萌生株的丛类型增加得尤为显著;叶片数量、叶片总生物量与未调控前相比增加明显,叶片面积按保留萌生株数量由多到少逐渐变小.调控后,每丛保留3支萌生株的丛产生的种子最多,但自然状态丛种子单粒重最大.