Floristic analysis is considered inadequate as the sole criterion for classifying plant communities which are dynamic aggregates of organisms. Plant communities should be graded according to the functional adaptation of the component species to the phytosociological environment. Attention is focused on a classification of dispersal mechanisms. A new scheme is proposed, based on morphological fe...

通过对大青沟分布的49种木本植物,其中包括23种乔木,26种灌木的果实类型组成和所占的 比例及其水分生态型分析,结果表明:大青沟木本植物水分生态型以中生植物为主,占87.76%;果实类型主要是蒴果、浆果、核果和翅果,分别占 26.53%、22.45%、16.33%和16.33%,其次为坚果和梨果,分别占6.12%、6.12%,瘦果、荚果和骨突果所占比例最小,分别占 2.04%、2.04%和2.04%.木本植物群落的垂直分布决定植物对水资源利用方式不同,以地下水为利用资源的木本植物,其果实主要是通过动物来传播 的,而以地表水为利用资源的木本植物,其果实主要是通过风来传播的.由此根据现有木本植物果实类型组成和生态型谱初步推断,大青沟植物群落的形成过程是以 风为媒介,使植物果实扩散和定居而形成的,之后又以动物为媒介,使植物果实通过动物扩散和定居,从而形成目前不同生态型的植物群落,而不是大青沟作为植物 避难所,原有地带性植被的残存.

通过对大青沟分布的49种木本植物,其中包括23种乔木,26种灌木的果实类型组成和所占的 比例及其水分生态型分析,结果表明:大青沟木本植物水分生态型以中生植物为主,占87.76%;果实类型主要是蒴果、浆果、核果和翅果,分别占 26.53%、22.45%、16.33%和16.33%,其次为坚果和梨果,分别占6.12%、6.12%,瘦果、荚果和骨突果所占比例最小,分别占 2.04%、2.04%和2.04%.木本植物群落的垂直分布决定植物对水资源利用方式不同,以地下水为利用资源的木本植物,其果实主要是通过动物来传播 的,而以地表水为利用资源的木本植物,其果实主要是通过风来传播的.由此根据现有木本植物果实类型组成和生态型谱初步推断,大青沟植物群落的形成过程是以 风为媒介,使植物果实扩散和定居而形成的,之后又以动物为媒介,使植物果实通过动物扩散和定居,从而形成目前不同生态型的植物群落,而不是大青沟作为植物 避难所,原有地带性植被的残存.

We studied the seed dispersal spectra of 46 Iberian plant communities of five types: potential woodland, forest fringe, substitutional scrubland, nitrophile communities and montane communities. There were no significant differences between the spectra of communities of the same type from Mediterranean and Eurosiberian regions. Biotic dispersal is most common at mature stages of succession, and abiotic dispersal at immature stages.

种子扩散方式对植物物种分布、种群动态及群落组成都有重要影响,但目前有关种子扩散方式的数据还很欠缺。植物的生活史性状与种子扩散方式联系密切,通过植物生活史性状预测种子的扩散方式是一种有效的研究手段。本文基于我国360种植物的生长型、株高、种子质量和果实类型以及种子扩散方式的数据集,随机抽取288个物种数据（80%）作为训练样本,采用神经网络、决策树、费舍尔线性判别和支持向量机算法,分别建立种子扩散方式的预测模型,将其余72个物种数据（20%）用于模型检验。以1,000次随机抽样后的平均判别正确率作为模型预测效果的评价指标。结果表明：用生长型、株高、种子质量及果实类型作为主要预测变量,构建的神经网络、决策树、费希尔线性判别和支持向量机模型均能达到较好的预测效果,准确率分别为78.90%、77.09%、77.81%和78.14%,其中以神经网络模型的预测效果最好。进一步研究发现,神经网络模型对动物扩散、无助力扩散和风扩散的预测效果分别为81.32%、74.90%和81.45%。本研究为植物种子扩散方式预测提供了一种新的思路。

种子扩散方式对植物物种分布、种群动态及群落组成都有重要影响,但目前有关种子扩散方式的数据还很欠缺。植物的生活史性状与种子扩散方式联系密切,通过植物生活史性状预测种子的扩散方式是一种有效的研究手段。本文基于我国360种植物的生长型、株高、种子质量和果实类型以及种子扩散方式的数据集,随机抽取288个物种数据（80%）作为训练样本,采用神经网络、决策树、费舍尔线性判别和支持向量机算法,分别建立种子扩散方式的预测模型,将其余72个物种数据（20%）用于模型检验。以1,000次随机抽样后的平均判别正确率作为模型预测效果的评价指标。结果表明：用生长型、株高、种子质量及果实类型作为主要预测变量,构建的神经网络、决策树、费希尔线性判别和支持向量机模型均能达到较好的预测效果,准确率分别为78.90%、77.09%、77.81%和78.14%,其中以神经网络模型的预测效果最好。进一步研究发现,神经网络模型对动物扩散、无助力扩散和风扩散的预测效果分别为81.32%、74.90%和81.45%。本研究为植物种子扩散方式预测提供了一种新的思路。

1 The dispersal mode adopted by a plant species is frequently associated with other attributes of the plant and its habitat. In this paper we review these associations and present a set of hypotheses which, when considered together, make a probabilistic prediction of the dispersal mode adopted by a plant species. When applied to a species list, the hypotheses can be used to generate a prediction of its dispersal spectrum, i.e. the percentages of different dispersal modes that have been adopted. 2 The formulation of such a set of hypotheses has several purposes: (i) to summarize existing knowledge about dispersal adaptations and their interrelations with other attributes of plants and their habitats; (ii) to couch that knowledge in such a way that falsifiable predictions can be made; (iii) to arrive at provisional conclusions about which factors are the most important in shaping the evolution of dispersal mode in different plants or different environments. 3 The review of relationships between dispersal mode and other attributes of plants and their habitats lead to the following provisional conclusions; (i) seeds larger than 100 mg tend to be adapted for dispersal by vertebrates while those smaller than 0.1 mg tend to be unassisted; most seeds, however, are between 0.1 and 100 mg, and in this range all of the dispersal modes are feasible; (ii) plant growth form and stature (sometimes in relation to the canopy height of the vegetation) seem to exclude certain dispersal modes; (iii) the availability of specific dispersal vectors seems rarely to be an important determinant of dispersal mode; (iv) attributes of the physical environment also seem rarely to be important, except indirectly through their influence on plant stature and seed size.

Progressive multifocal leukoencephalopathy (PML) is a rare but usually fatal demyelinating disease of the central nervous system in patients who are immunocompromised. It is characterized by rapid neurological deterioration associated with progressive white matter changes on imaging and is confirmed by isolation of the causative virus in the cerebrospinal fluid or brain tissue. Currently there are no effective treatments for PML and outcomes remain poor even after reversal of the immunocompromised state. This case series describes three patients with different underlying pathologies and varying presentations who were all diagnosed with PML and referred to a palliative care service.

通过甘肃木本植物生活型和果实类型构成式样对水热因子的相关分析指出 :(1 )乔木类、大灌木、藤木和寄生植物与各水热因子呈正相关 ,小灌木与各水热因子均呈负相关 ,灌木则与平均降水和平均温度呈负相关 ;(2 )常绿类型与水热因子呈正相关 ,落叶类与水热因子呈负相关 ;(3 )走廊小区的常绿类型比例较水热条件较好的中部小区高 ,原因在于其植物区系特殊的起源背景 ;(4)湿润度与干果类呈显著负相关 ,与肉果类呈显著正相关 ,干果类和肉果类的成因可能与植物生长环境中水分状况密切相关 ;(5 )球果类与热量因子呈负相关 ,与水分因子呈正相关 ,与湿润度呈显着正相关 ;翅果、坚果、核果、果、颖果与各水热因子均呈正相关关系 ;蒴果与各水热因子呈负相关关系 ,干冷生境可能是其形态发生的重要驱动因素 ;胞果类与年均降水量呈显着负相关 ,表明干旱的生境有利于胞果类的发育 ;(6 )物种多样性、生活型和果实类型丰富度以及树体的高度在水热梯度上表现出相关变化趋势。研究进一步指出 ,不同果实类型生长发育对水热条件均有特定要求 ,弄清果实演化序列将有助于分析特定植物群落果实类型的构成式样和揭示环境变化对植物生长发育的影响 ,未来应加强果实系统发育对生态因子梯度变化响应机制的研究

通过甘肃木本植物生活型和果实类型构成式样对水热因子的相关分析指出 :(1 )乔木类、大灌木、藤木和寄生植物与各水热因子呈正相关 ,小灌木与各水热因子均呈负相关 ,灌木则与平均降水和平均温度呈负相关 ;(2 )常绿类型与水热因子呈正相关 ,落叶类与水热因子呈负相关 ;(3 )走廊小区的常绿类型比例较水热条件较好的中部小区高 ,原因在于其植物区系特殊的起源背景 ;(4)湿润度与干果类呈显著负相关 ,与肉果类呈显著正相关 ,干果类和肉果类的成因可能与植物生长环境中水分状况密切相关 ;(5 )球果类与热量因子呈负相关 ,与水分因子呈正相关 ,与湿润度呈显着正相关 ;翅果、坚果、核果、果、颖果与各水热因子均呈正相关关系 ;蒴果与各水热因子呈负相关关系 ,干冷生境可能是其形态发生的重要驱动因素 ;胞果类与年均降水量呈显着负相关 ,表明干旱的生境有利于胞果类的发育 ;(6 )物种多样性、生活型和果实类型丰富度以及树体的高度在水热梯度上表现出相关变化趋势。研究进一步指出 ,不同果实类型生长发育对水热条件均有特定要求 ,弄清果实演化序列将有助于分析特定植物群落果实类型的构成式样和揭示环境变化对植物生长发育的影响 ,未来应加强果实系统发育对生态因子梯度变化响应机制的研究

干扰在森林生态系统中普遍存在,并影响森林的更新和演替.动物传播种子是种子更新的必经阶段,其对森林干扰的响应在一定程度上能够预测未来的森林群落组成和结构变化,对于明确森林演替方向具有重要意义.本文论述了森林干扰对动物传播种子有效性(包括动物传播种子的数量和质量)影响研究的生态学意义,全面揭示了自然干扰(火干扰、林窗干扰等)和人为干扰(生境破碎化、狩猎、采伐等)对动物传播种子数量、传播距离以及传播后幼苗更新影响的研究进展,指出干扰通过影响动物种群动态,进而造成动物传播种子数量发生了改变,动物传播种子的距离对干扰的响应基本表现出轻微负相关;干扰对传播后幼苗更新的影响结果因干扰类型的不同而复杂多变,干扰迹地环境因子的变化也影响着传播后的种子萌发和幼苗更新.干扰对动物传播种子有效性影响研究中存在的问题,主要表现为火干扰迹地恢复过程、增益性的干扰(如抚育、间伐、林窗)等对种子传播有效性影响研究的匮乏,以及忽略了温带森林内的干扰对动物传播种子的影响等.今后,应开展干扰对种子传播有效性的长期研究;对于干扰多发地带的森林,应高度重视增益性干扰影响动物传播植物种子的研究.

干扰在森林生态系统中普遍存在,并影响森林的更新和演替.动物传播种子是种子更新的必经阶段,其对森林干扰的响应在一定程度上能够预测未来的森林群落组成和结构变化,对于明确森林演替方向具有重要意义.本文论述了森林干扰对动物传播种子有效性(包括动物传播种子的数量和质量)影响研究的生态学意义,全面揭示了自然干扰(火干扰、林窗干扰等)和人为干扰(生境破碎化、狩猎、采伐等)对动物传播种子数量、传播距离以及传播后幼苗更新影响的研究进展,指出干扰通过影响动物种群动态,进而造成动物传播种子数量发生了改变,动物传播种子的距离对干扰的响应基本表现出轻微负相关;干扰对传播后幼苗更新的影响结果因干扰类型的不同而复杂多变,干扰迹地环境因子的变化也影响着传播后的种子萌发和幼苗更新.干扰对动物传播种子有效性影响研究中存在的问题,主要表现为火干扰迹地恢复过程、增益性的干扰(如抚育、间伐、林窗)等对种子传播有效性影响研究的匮乏,以及忽略了温带森林内的干扰对动物传播种子的影响等.今后,应开展干扰对种子传播有效性的长期研究;对于干扰多发地带的森林,应高度重视增益性干扰影响动物传播植物种子的研究.

Abstract. We compare the dispersal spectra of diaspores from varied plant communities in Australia, New Zealand, and North America, assigning dispersal mode to each diaspore type on the basis of apparent morphological adaptations. Species with ballistic and external dispersal modes were uncommon in most communities we surveyed. Ant dispersal was also rather uncommon, except in some Australian sclerophyll vegetation types. The frequency of vertebrate dispersal ranged up to 60% of the flora, the highest frequencies occurring in New Zealand forests. Wind dispersal ranged as high as 70% of the flora, with the highest values in Alaska, but usually comprised 10 30% of the flora. Many species in most communities had diaspores with no special morphological device for dispersal. Physiognomically similar vegetation types indifferentbiogeographic regions usually had somewhat dissimilar dispersal spectra. The frequency of dispersal by vertebrates often increased and the frequency of species with no special dispersal device decreased along gradients of increasing vertical diversity of vegetation structure. Elevation and moisture gradients also exhibited shifts in dispersal spectra. Within Australia, vertebrate- and wind-dispersal increased in frequency along a soil-fertility gradient, and dispersal by ants and by no special device decreased. Habitat breadths (across plant communities) and microhabitat breadths (within communities) for species of each major dispersal type did not show consistent differences, in general. Ant-dispersed species often had lower cover-values than other species in several Australian vegetation types.

In this paper, we described fruit and seed traits of 145 tree species from a 20 ha tropical seasonal rainforest dynamics plot. The fruiting of most tree species occurred in rainy season(7103%). Fewer species had fruit in dry season. Flesh fruits, such as drupes, capsules and berries, were very common in the plot and, fruits were mainly black, yellow and brown colored. Most species were animal dispersed(5655%). Species with large seeds(maximum seed length >10 mm)were predominate(5310%), followed by mediumsized seeds(2-10 mm), and small seeds(

In this paper, we described fruit and seed traits of 145 tree species from a 20 ha tropical seasonal rainforest dynamics plot. The fruiting of most tree species occurred in rainy season(7103%). Fewer species had fruit in dry season. Flesh fruits, such as drupes, capsules and berries, were very common in the plot and, fruits were mainly black, yellow and brown colored. Most species were animal dispersed(5655%). Species with large seeds(maximum seed length >10 mm)were predominate(5310%), followed by mediumsized seeds(2-10 mm), and small seeds(

喀斯特生境与生物多样性的关系及其对人为干扰的响应是喀斯特地区生态恢复的重要内容.该文以云南石林为例 对此进行研究.根据喀斯特溶痕与土壤、植物生长发育关系把石林的溶痕生境划分为溶蚀廊道、溶槽、裂隙溶沟、溶坑和溶蚀石堆等5种.依据石林的现有植被与演 替特征,选择了原生林、次生林、灌丛、灌草丛和石漠化草丛5种群落进行调查.在每一个样地中设置10个10 m×10 m的样方,采用记名计数样方法分片调杏溶痕生境中的木本植物,并区分更新层的萌生苗与实生苗;采用Shannon-wiener指数、Pielou指数、 Simpson指数、Margalef指数进行生物多样性计算.调查结果显示:(1)溶痕生境的长度、宽度变化较大.溶痕生境结构比例随群落演替而变化, 其原因可能在于所处演替阶段和干扰程度的差异;(2)在各种溶痕生境中,随着群落的退化.实生更新物种数与实生株数大致表现为递减,在严重退化阶段部分溶 痕生境中没有实生苗的分布,而萌生更新的物种数则以灌从为峰值向两极减少,个体数变化较大.计算结果显示:在各类溶痕生境(溶蚀石堆除外)中,实生苗的多 样性、丰富度、均匀度大致呈现随群落的退化而降低,优势度增加;萌生苗多样性、均匀度、丰富度除溶蚀廊道递减的趋势明显外,其他类型变化较大.不同演替阶 段植物更新策略不同.在喀斯特森林生态系统中,随着群落的退化,植物更新逐步趋向于营养繁殖,其部分原因在于特殊的溶痕生境(除溶蚀廊道)能保存一些植物 残体,而这些残体在反复的干扰下不断萌出茎干(采用营养繁殖)以实现物种的持续生态位,萌生茎干的成熟为生物多样性维持与生态恢复提供繁殖体来源.

喀斯特生境与生物多样性的关系及其对人为干扰的响应是喀斯特地区生态恢复的重要内容.该文以云南石林为例 对此进行研究.根据喀斯特溶痕与土壤、植物生长发育关系把石林的溶痕生境划分为溶蚀廊道、溶槽、裂隙溶沟、溶坑和溶蚀石堆等5种.依据石林的现有植被与演 替特征,选择了原生林、次生林、灌丛、灌草丛和石漠化草丛5种群落进行调查.在每一个样地中设置10个10 m×10 m的样方,采用记名计数样方法分片调杏溶痕生境中的木本植物,并区分更新层的萌生苗与实生苗;采用Shannon-wiener指数、Pielou指数、 Simpson指数、Margalef指数进行生物多样性计算.调查结果显示:(1)溶痕生境的长度、宽度变化较大.溶痕生境结构比例随群落演替而变化, 其原因可能在于所处演替阶段和干扰程度的差异;(2)在各种溶痕生境中,随着群落的退化.实生更新物种数与实生株数大致表现为递减,在严重退化阶段部分溶 痕生境中没有实生苗的分布,而萌生更新的物种数则以灌从为峰值向两极减少,个体数变化较大.计算结果显示:在各类溶痕生境(溶蚀石堆除外)中,实生苗的多 样性、丰富度、均匀度大致呈现随群落的退化而降低,优势度增加;萌生苗多样性、均匀度、丰富度除溶蚀廊道递减的趋势明显外,其他类型变化较大.不同演替阶 段植物更新策略不同.在喀斯特森林生态系统中,随着群落的退化,植物更新逐步趋向于营养繁殖,其部分原因在于特殊的溶痕生境(除溶蚀廊道)能保存一些植物 残体,而这些残体在反复的干扰下不断萌出茎干(采用营养繁殖)以实现物种的持续生态位,萌生茎干的成熟为生物多样性维持与生态恢复提供繁殖体来源.