Disturbance indicators and population decline of logged species in Mt. Elgon Forest,Kenya

Mount (Mt) Elgon forest in western Kenya is important for biodiversity, environmental protection and socio‐economic development. Characterizing forest conditions is essential for evaluation of sustainable management and conservation activities. This paper covers findings of a study which determined and analysed indicators useful in monitoring disturbance levels in the Mt Elgon Forest. A systematic survey was carried out and covered 305 plots of 0.02 ha and 250 smaller nested regeneration plots along 10 belt transects that were distributed in five blocks within the moist lower montane forest type. Collected and analysed data include types of disturbance, tree species composition, abundance and logged species. Correlation breakdown among disturbance types revealed that, paths were indicators of the number of tree harvesting sites (r_s =1.00, P < 0.01) and of de‐vegetated areas through grass harvesting (r_s = 0.90, P = 0.04). Solanum mauritianum Scop. was an indicator of old‐charcoal production sites. Logging targeted 13 tree species and harvested trees with diameter at breast height above 20 cm. The most exploited species were Olea capensis L. and Deinbolia kilimandscharica Taub. All exploited species had low regeneration but tree regeneration was not an effective indicator of logging.     

Effects of grazing and cultivation on forest plant communities in Mount Elgon National Park, Uganda

Plant communities in the montane forest of Mount Elgon National Park were studied in order to assess the impact of grazing and cultivation on species composition. Present and former land uses, tree, shrub and herb species, soil properties and the percentage cover and height of trees, shrubs and herbs were determined in 40 plots. An indirect ordination of these plots showed that species composition was primarily determined by successional stage and agricultural disturbance. In forest plots (ordinated separately) where the widest range of former and current grazing intensities had occurred, evidence of grazing history, soil phosphorus and vegetation height correlated negatively with the strongest ordination axis. Least grazed forest plots had fewer tree seedlings and saplings than more intensively grazed plots. This may be due to the increase in Mimulopsis alpina (Acanthaceae) in less grazed forest where tree regeneration might otherwise be more advanced. Tree seedlings and saplings were uncommon in the forest, rarely exceeding 30cm in height and there was no tree understorey. Although grazing is important for preserving species diversity in Mount Elgon National Park through the maintenance of species-rich grasslands, long-term effects on montane forest communities must be considered in future park management.     

The Vanishing De Brazza's Monkey (Cercopithecus neglectus Schlegel) in Kenya

We conducted a trail survey of De Brazza's monkey (Cercopithecus neglectus) on Mt. Elgon and the Cherangani Hills between October 1994 and February 1995. The objectives were to assess the status and distribution of the species and its habitats and to formulate recommendations on its conservation. We counted a total of 49 monkeys: 3 groups and 6 lone individuals near Kimothon River (Mt. Elgon) and 4 groups and 6 lone individuals at Kapolet Forest Reserve and its environs (Cherangani Hills). The mean group size is 6.6. Wanton habitat destruction was evident in all the forest habitats. The species now inhabits unprotected remnant strips of riverine forest. Furthermore, the Kapolet Forest Reserve offers little or no protection to De Brazza's monkeys or their habitat. Translocation of the monkeys from unprotected areas to a protected habitat is recommended as an urgent conservation measure to save the De Brazza's population in Mt. Elgon and the Cherangani areas of Kenya.     

中国中亚热带东部常绿阔叶林主要类型的群落多样性特征

 本文通过10个地区61个样地资料分析,研究了中亚热带东部常绿阔叶林群落多样性特征及其随纬度、海拔梯度的变化。结果表明,中亚热带东部常绿阔叶林群落丰富度为49±17种(样地面积400m2),各层次的多样性表现为灌木层(包括幼树与幼苗)>乔木层>草本层。常绿阔叶林各类型间的差异远比落叶阔叶林与多样性较低的常绿阔叶林之间的差异大。各层次中变化幅度从大到小的顺序为：草本层>乔木层>灌木层。在所研究地区常绿阔叶林的群落多样性没有表现出明显的随纬度梯度和海拔梯度的变化规律。     

Species Diversity and Altitudinal Gradient Patterns of Evergreen Broad leaved Forest in MeihuashanNational Natural Reserve,Fujian Province

In China, evergreen broad leaved forests (EBLFs) is one of the most important vegetation types which was widly distributed in subtropical area, and it plays a very important role in the global biological diversity and natural environment conservation also. In order to reveal species diversity and altitudinal gradient patterns of evergreen broad leaved forest in Meihuashan National Natural Reserve, Fujian Province. Five altitude transects were set up at a vertical interval of 200m between 375m and 1300m above sea level in the EBLFs distribution areas, and twenty four quadrats(14400m2) had been surveyed. Species richness(S), species richness index (dGl), Simpson index (D), Shannon Wiener index (H′), Pielou evenness index (J) had been used for analysis of species diversity and altitudinal gradient pattern of EBLFs. The average value of S, dGl, H′,J and D were 64.42, 10.75, 5.75, 3.50, 0.58 respectively. The difference of community species diversity index(S, dGl, D, H′, and J) was extremely significant between transects, and the altitudinal gradient patterns of species diversity presented the unimodal variable trend, with a peak in the mid altitude(700m-900m). The species richness and Shannon Wiener index of different layer were ranked as shrub layer (include young tree and the plants between layers)>arbor layer>herb layer. The species richness of tree and shrub layer, and Shannon Wiener index of tree layer were significantly different between at transects, and trends of altitude gradient was similar to community. The Shannon Wiener index of shrub layer and herb layer, and the species richness of herb layer did not change significantly along elevation gradient. Therefore, plant species diversity distribution pattern presented a unimodal variable trend along an elevation gradient, and supported “mid domain model” in EBLFs of Meihuashan National Nature Reserve.     

贺兰山木本植物群落物种多样性的海拔格局

 贺兰山位于中国温带草原和温带荒漠的过渡带,是研究干旱区山地物种多样性海拔格局的理想区域。该文通过样方法调查研究区的森林和灌丛群落,并运用广义可加模型分析物种多样性的海拔分布格局。结果表明：1）海拔是物种丰富度的重要影响因子,一般能解释原始数据30%～40%的变差。2）对于森林和灌丛群落,草本植物都是群落中比例最高的物种, 而且决定了群落总物种丰富度的海拔分布格局。3）森林群落的乔木层物种丰富度在中海拔区域最高,反映了中海拔区域相对优越的水热条件。灌木层和草本层的物种丰富度明显受到乔木层郁闭度的影响,有随海拔升高而降低的趋势。4）灌丛群落的灌木层和草本层物种丰富度均呈单峰格局,皆因低海拔的干旱和高海拔的寒冷抑制了多数物种的生存,仅气候条件适宜的中海拔区域能够生存丰富的物种。     

福建梅花山常绿阔叶林植物物种多样性及其海拔梯度格局

常绿阔叶林是福建梅花山国家级自然保护区地带性植被。采用样带与典型群落调查法对区内的常绿阔叶林14400m2样地展开调查,并对植物多样性海拔梯度格局进行分析,结果表明：（1） 群落植物物种丰富度、Gleason丰富度指数、Simpson指数、Shannon Wiener指数和Pielou均匀度指数的均值分别为64.42、10.75、5.75、3.50、0.58,且这5种指数在各样带间差异极为显著,并随海拔的升高均呈单峰曲线变化,峰值出现在海拔700m~900m。（2） 群落各层次的植物物种丰富度、Shannon Wiener指数均呈现灌木层（包括幼树和层间植物）〉乔木层〉草本层的特征。乔木、灌木层物种丰富度与乔木层Shannon Wiener指数在海拔梯度上的样带间差异极显著,变化趋势与群落相似;灌木层与草本层Shannon Wiener指数以及草本层物种丰富度随海拔梯度变化不明显。因此,梅花山自然保护区常绿阔叶林植物物种多样性的海拔梯度格局呈现单峰分布,并支持中间高度膨胀模式（mid domain model）。     

特有珍稀植物宝华玉兰种群分布格局和群落特征

采用相邻格子样方法和典型样地法研究镇江宝华山国家森林公园珍稀植物宝华玉兰的种群分布格局和群落物种多样性。从分布格局看,宝华玉兰种群在半自然样地Q1中为聚集分布,但聚集强度不高,而在另外3个样地中均为随机分布。从群落特征看,4个样地共有维管植物89种,隶属于43科74属;群落分层明显,但宝华玉兰为亚优势种;半自然林中各层次的物种多样性Shannon-Wiener指数为草本层>灌木层>乔木层,而在自然样地中,则为草本层>乔木层>灌木层。     

白龙江上游地区森林植物群落物种多样性的研究

 白龙江上游地区属长江防护林工程重点地区之一。根据36个样地的调查资料,分析了该地区森林植物群落物种多样性的特征：群落内各层物种丰富度指数的大小顺序为“灌木层>草本层>乔木层”;均匀度指数变化比较复杂,在杜鹃巴山冷杉（Rhododendron fastigiatum-Abies fargesii）林中为“草本层>灌木层>乔木层”,在苔藓巴山冷杉林中为“乔木层>灌木层>草本层”,其余群落中为“灌木层>草本层>乔木层”;多样性指数的大小顺序为“乔木层<灌木层和草本层”,而灌木层与草本层的多样性指数随林分郁闭度变化而变化,在郁闭度30%的杜鹃巴山冷杉林中,草本层大于灌木层,在郁闭度47%的箭竹巴山冷杉林中,草本层和灌木层相当,在郁闭度55%以上的各个群落内,灌木层大于草本层。同一海拔不同坡向群落的物种多样性表现为分布于阳坡的油松（Pinus tabulaeformis）林大于分布于阴坡的草类云杉（Picea asperata）林。物种多样性沿海拔梯度的变化表现为随海拔升高先降低后增加,从海拔2 400 m的栎类阔叶林,2 600 m的草类云杉林,2 800 m的箭竹(Sinarundinaria nitida)巴山冷杉林,到3 000 m的苔藓巴山冷杉林和3 200 m的杜鹃巴山冷杉林,物种多样性依次下降,到海拔3 400 m的高山杜鹃（Rhododendron fastigiatum）灌丛,物种多样性增加。物种多样性在紫果云杉(Picea purpurea)林的演替系列中表现为随群落演替发展而增加,后降低,在针阔混交林阶段达到最大。