不同渍水时间对苗期和花期大豆生长及碳氮代谢的影响

以大豆品种南农99.6为材料,通过盆栽试验研究了苗期和花期渍水对大豆生长及碳氮代谢的影响.结果表明: 渍水显著抑制了大豆的生长,植株生物量、叶面积、叶片色素含量和光合速率均显著下降,而丙二醛(MDA)含量显著升高;随着渍水时间的延长,各生理指标的变化幅度增大;渍水胁迫解除后有一定的恢复,渍水10 d处理后恢复能力较渍水20 d处理强.可溶性碳、氮物质及关键酶对渍水反应不同,可溶性糖含量以及叶片谷氨酰胺合成酶和蔗糖合成酶的活性上升,而可溶性蛋白含量下降.渍水对苗期大豆植株生物量、叶面积和MDA含量的影响比花期小.苗期和花期渍水时间越短,大豆受到的伤害越小,其恢复能力也越强.渍水时间在10 d内,大豆植株能够通过自身的调节逐渐恢复.     

Pathways and determinants of early spontaneous vegetation succession in degraded lowland of South China

Continuous and prolonged human disturbances have caused severe degradation of a large portion of lowland in South China, and how to restore such degraded ecosystems becomes an increasing concern. The process and mechanisms of spontaneous succession, which plays an important role in vegetation restoration, have not been adequately examined. To identify the pathways of early spontaneous vegetation succession, 41 plots representing plant communities abandoned over different times were established and Investigated. The communities and indicator species of the vegetation were classified by analyzing the important values of plant species using multivariate analyses. The reaults indicated that the plant species could be classified into nine plant communities repreaenting six succession staages. The pathway and species composition alao changed in the process of succession. We also meaeurad 13 environmental variables of microtopography, soil structure and soil nutrition in each plot to examine the driving forces of auccession and the vegetation-environment relationships. Our resulta ahowed that the environmental variables changed in diverse directions, and that aoil bulk density, soil water capacity and soU acidity were the most important factors.     

The effect of a seed source on primary succession in a forest ecosystem

An analysis of the Relative Importance Value Index (RIVI) of later successional tree species and the Shannon diversity indexH of all tree and shrub species was undertaken on previously mined sites within a sparsely forested area in central Florida, USA. A comparative analysis of the distance to a seed source and the age of a site suggested that the distance to a seed source was the best predictor (R ²=0.85) of the regeneration of the later successional species and a good predictor of species diversity. Both theRIVI of the later successional species and the diversity index decreased with the distance from the seed source. The lack of a seed source containing climax species resulted in arrested succession at some sites. It is suggested that biological information is the causative means of succession and the dispersal of this information entails spatial dependency while its introduction and development are time dependent processes.Research was part of a project of the Center for Wetlands, University of Florida, Gainesville under contract with the Florida Institute of Phosphate Research. Interactions of Wetlands with Phosphate Mining, H. T. Odum and G. R. Best, principal investigators. B. T. Rushton, J. Butner, G. R. Best, R. S. Schnoes and S. R. Humphrey are thanked for the use of their data.     

植被原生演替研究进展

对植被原生演替的国内外研究进展进行了评述。植被原生演替过程受到生物因素和非生物因素的共同影响。生物因素包括种子的传播方式、对原生环境的适应能力及物种之间的关系等,依靠风力传播、对裸地的极端环境具有较强适应能力的物种更容易成为原生裸地的早期定居者,某些微生物在植物的定居具有非常重要的作用。非生物因素则包括裸地表面的形状(凹、凸、平)、粗糙度、与岩石的距离等,一些特殊的微环境能够为植物的定居创造更为优越的水分、养分条件,促进植物的定居。植被原生演替是生物驱动因素与环境阻力相互作用的结果,二者的消长决定原生演替进行的模式。大量的研究表明,植被原生演替过程并不完全遵循地衣-苔藓-草本植物-木本植物的顺序,不同环境条件下的植被原生演替过程表现出明显的复杂性,这种复杂性与原生裸地环境条件的复杂性有关。该领域的研究将侧重于以下两个方面:早期定居种的适生特征(包括解剖的和生理的)以及各种微生物对植物定居过程的影响;各种非生物环境因素对植物定居的影响。     

江苏省海滩植被演替的研究

江苏省海滩植被可分为滨海盐土植被、盐沼植被及海滩沙生植被三个基本类型。本文论述了这些植被类型的演替规律。滨海盐土植被与盐沼植被的演替,外因于土壤盐分含量递减与有机质含量的递增;海滩沙生植被的演替,外因于土壤沙颗粒大小及其相应的土壤含水量的变化,所以海滩植被演替为外因动态演替。     

干扰与生态系统演替的空间分析

演替不光是生态系统在时间序列上的替代过程,而且也是生态系统在空间上的动态演变。演替的空间属性有演替系列的格局、范围、尺度、演替方向和速率、稳定的程度、多样性、以及在自然和人为干扰下的恢复等。干扰破坏了生态系统的稳定性,形成生态系统结构和功能的破损,使生态系统处于一种过渡状态。但是干扰也是生态系统演替的外在驱动力,自然的和人为的干扰引起的生态系统的对称性破缺,推动了系统的进化和演变。外界因素作用于生态系统的干扰因子包含了很多种类,如火、风倒、洪水、病虫害、人类活动等。干扰的属性有范围、频度、季节、强度、损害度、返回时间和循环周期。讨论了这些干扰的类型和生态系统演替所具有空间的特征,并且介绍了干扰和生态系统演替空间分析常用的方法,如空间解绎和辨识、空间统计分析、空间格局分析和地理信息系统的空间分析、以及空间模拟。利用了一些典型的实例来深入阐明空间分析在干扰和生态系统演替中的应用。利用美国加利福尼亚北部火干扰的历史和空间分布的记录,进行了火干扰的空间分析的研究;用Spies等在美国俄勒冈州西部1972～1988年的多时段的变化的实例说明了收获干扰的影响;利用俄勒冈州东部山地的主要两个虫害(山地松树甲虫(Mountain Pine Beetle)和云杉蚜虫(Spruce Budworm))22a的数据分析了病虫害干扰的空间分布格局及其与海拔、温度、降水和植被类型的关系。在生态系统演替的空间分析方面,以美国俄勒冈州西部的历史和现实植被演替格局的分析为例,讨论了如何利用空间分析方法研究区域尺度生态系统的演替,同时比较了历史和现实植被的空间格局指数的变化;用两个实例来说明空间分析在辨识大陆和国家尺度生态系统变迁中的应用,一个是美国原生的老森林(Old～growth)植被从1620年到1920年,300a的空间格局变化,另外一个是加拿大植被从1600年到2000年,大约400a的空间分布变化。最后,对生态系统演替的空间分析的一些重要问题作了探讨,例如：空间分析可否帮助确定地带性顶极群落;如何将外貌与成分结合更好地识别生态系统演替的空间格局与演变趋势;以及如何利用空间分析研究由于人类活动干扰加剧所造成的生态系统自然演化规律的异化。     

The role of frugivorous bats in tropical forest succession

Discussion of successional change has traditionally focused on plants. The role of animals in producing and responding to successional change has received far less attention. Dispersal of plant propagules by animals is a fundamental part of successional change in the tropics. Here we review the role played by frugivorous bats in successional change in tropical forests. We explore the similarities and differences of this ecological service provided by New and Old World seed-dispersing bats and conclude with a discussion of their current economic and conservation implications. Our review suggests that frugivorous New World phyllostomid bats play a more important role in early plant succession than their Old World pteropodid counterparts. We propose that phyllostomid bats have shared a long evolutionary history with small-seeded early successional shrubs and treelets while pteropodid bats are principally dispersers of the seeds of later successional canopy fruits. When species of figs (Ficus) are involved in the early stages of primary succession (e.g. in the river meander system in Amazonia and on Krakatau, Indonesia), both groups of bats are important contributors of propagules. Because they disperse and sometimes pollinate canopy trees, pteropodid bats have a considerable impact on the economic value of Old World tropical forests; phyllostomid bats appear to make a more modest direct contribution to the economic value of New World tropical forests. Nonetheless, because they critically influence forest regeneration, phyllostomid bats make an important indirect contribution to the economic value of these forests. Overall, fruit-eating bats play important roles in forest regeneration throughout the tropics, making their conservation highly desirable.     

Tertiary succession: a new concept to help vegetation restoration

Restoration is the human activity of manipulating vegetation with the aim of accelerating attainment of stable vegetation. But current procedures seem to arrest succession instead. A comparison of primary and secondary successions with restoration activities suggests there is little overlap in these concepts. Thinking of the process of restoration as a tertiary succession helps highlight managerial options which may improve success, especially by addressing environmental and biological legacies.     

不同起始状态对草原群落恢复演替的影响

内蒙古典型草原,由于过度放牧利用,绝大部分草原处于退化状态.为了使退化草原得到较好的恢复,以锡林郭勒盟白音锡勒牧场典型草原为研究对象,比较分析了在不同起始状态下的草原群落,经过6a的自然恢复,其各自的群落组成,地上生物量及共有种的植株高度、节间长、叶长、叶宽,土壤紧实度和容重.结果表明:1)不同放牧率的植物群落,经过6a的禁牧恢复,群落类型发生了变化且群落趋于一致.2)当放牧率SR≤5.33羊/hm2(SR4)时,演替起始状态对草原群落地上生物量的恢复没有影响;当放牧率SR＞5.33羊/hm2时,演替起始状态对草原群落地上生物量的恢复产生影响,其结果是导致当前生物量降低,不利于草原的恢复.3)不同放牧率植物群落的植物个体特征趋于一致,“个体小型化”现象消失.同时,也说明群落恢复演替的起点不同,正常化的时间没有太大的变化.4)不同放牧率植物群落的土壤紧实度和容重经过6a的禁牧恢复,没有得到完全恢复,但均达到一致的水平.     

热带森林植被生态恢复研究进展

热带森林是地球上生物多样性最高和生态功能最为强大的植被类型之一,在维护全球生态平衡中起着至关重要的作用,同时也为人类社会提供着多种多样的物质资源和生态系统服务。然而热带森林是目前生物多样性消失最快和生态功能退化最为严重的生态系统之一,如何有效地保护现存的热带森林不再进一步退化,以及如何使已经退化的生态系统尽快得到恢复是生态学工作者面临的重要议题。不同方式、规模和强度的干扰对热带林的破坏程度及其以后的恢复过程产生的影响不同。除少数大型自然干扰事件外,采伐、刀耕火种、农业开发用地等人为干扰是造成当前热带森林植被大面积退化的主要原因。多种干扰交互作用、杂草与外来物种入侵、退化植被和土壤状况、残存植被组分及土壤种子库、退化植被周围的景观格局以及全球气候变化等因素都能够影响热带森林植被恢复的速度和方向。基于功能群的研究思想将可能为物种丰富的热带森林植被恢复的研究提供一个全新途径。     

The growing role of aquaculture in ecosystem restoration

Active restoration in aquatic systems is relatively underdeveloped. Aquaculture, often called gardening or artificial/controlled propagation in this context, is increasingly important in the theory and practice of aquatic restoration. This RE‐New contribution explores current ideas and examples in restoration aquaculture. Challenges exist, and these must be acknowledged and addressed. As impacts to aquatic systems persist, the next 25 years should see a greater role for aquaculture and seeds planted now will be important to future efforts. Eventually, aquaculture may be linked to aquatic systems restoration just as silviculture has been linked to forest restoration.     

Dynamics of nitrogen and phosphorus retention during wetland ecosystem succession

We compared the mechanisms of nitrogen (N) and phosphorus (P) removal in four young (<15 years old) constructed estuarine marshes with paired mature natural marshes to determine how nutrient retention changes during wetland ecosystem succession. In constructed wetlands, N retention begins as soon as emergent vegetation becomes established and soil organic matter starts to accumulate, which is usually within the first 1–3 years. Accumulation of organic carbon in the soil sets the stage for denitrification which, after 5–10 years, removes approximately the same amount of N as accumulating organic matter, 5–10 g/m²/yr each, under conditions of low N loadings. Under high N loadings, the amount of N stored in accumulating organic matter doubles while N removal from denitrification may increase by an order of magnitude or more. Both organic N accumulation and denitrification provide for long-term reliable N removal regardless of N loading rates. Phosphorus removal, on the other hand, is greatest during the first 1–3 years of succession when sediment deposition and sorption/precipitation of P are greatest. During this time, constructed marshes may retain from 3 g P/m²/yr under low P loadings to as much as 30 g P/m²/yr under high loadings. However, as sedimentation decreases and sorption sites become saturated, P retention decreases to levels supported by organic P accumulation (1–2 g P/m²/yr) and sorption/precipitation with incoming aqueous and particulate Fe, Al and Ca. Phosphorus cycling in wetlands differs from forest and other terrestrial ecosystems in that conservation of P is greatest during the early years of succession, not during the middle or late stages. Conservation of P by wetlands is largely regulated by geochemical processes (sorption, precipitation) which operate independently of succession. In contrast, the conservation of N is controlled by biological processes (organic matter accumulation, denitrification) that change as succession proceeds.     

A Markov approach for describing post-fire succession of vegetation

Vegetation dynamics in the coastal area of the Seto Inland Sea region in Japan, where wild fires occur frequently, were described using a stationary Markov model. In this region, vegetation types ofMiscanthus-Pleioblastus grassland,Lespedeza-Mallotus scrub,Pinus-Rhododendron forest andCrassocephalum-Erechtites community have been identified, and these show cyclic succession under the influence of fires. The model uses parameters determining fire frequency and rate of successional change to analyze the effect of variation in these parameters on the areal ratio of each vegetation type at equilibrium and on the time taken for one vegetation type to succeed another (elapsed successional time). The effect of fire frequency differs between hypothetical habitats with high and low productivity. A policy for vegetation management in areas of high and low productivity is proposed. The advantages and limitations of applying Markov models to studies of vegetation succession are also discussed.     

长白山植被类型特征与演替规律的研究

根据多次对长白山植被调查和长期定位观测资料 ,全面系统地总结了长白山植被类型特征和演替规律 ,详细描述了长白山地带性和非地带性植被类型的性质、组成、结构和分布规律 ,探讨了长白山植被演替与火山爆发的关系。提出长白山植被垂直分布基带应是红白松阔叶混交林 ,也是长白山地带性植被类型。但由于长期受人类活动影响 ,削弱了地带性表现 ,形成大面积的天然次生林和耕地。据此不应该认为 ,人类能消灭客观自然规律的植被分布的地带性 ,为了恢复地带性植被和定向改造自然 ,应引进地带性树种 ,营造结构合理、种类多样和稳定性强的森林群落。     

Forest succession in Kibale National Park, Uganda: implications for forest restoration and management

Forest succession was studied in four plots in former grasslands at the Ngogo study area in Kibale National Park, Uganda. The plots were located in areas that had been protected from fire for 0.58, 25, 9 and ≈30 years for plots 1, 2, 3 and 4, respectively. Species richness reflected the length of time that the plot had been protected from fire; it was highest in plot 4 and lowest in plot 1. Species density, stem density and basal area were all highest in plot 4 and lowest in plot 1. The species densities of plots 2 and 3 were not different. Similarly, plots 2 and 4 did not differ with regard to stem density or basal area. Animal seed dispersers played a vital role in the colonization of grasslands by forest tree species.     

崇明东滩湿地自然植被演替过程中储碳及固碳功能变化

采用实地调查与实验室测定相结合的方法,研究了崇明东滩湿地植被演替过程中储碳、固碳功能的变化.结果表明：不同演替阶段的湿地植被的现存碳储量及其分配格局特征存在较大差异.先锋物种海三棱藨草的现存碳储量仅占芦苇现存碳储量的13%;地下根茎为芦苇现存碳储量的主要场所,而地上部分是海三棱藨草碳储量的主要场所.处于潮滩湿地演替中后期的芦苇群落比处在生态演替早期的海三棱藨草群落具有更强的固碳能力,芦苇群落和海三棱藨草群落的年固碳能力分别为(1.63±0.39) kg·m^-2和(0.63±0.28) kg·m^-2,说明随着海三棱藨草群落向芦苇群落演替,其固碳能力不断增强.     

The role of remnant forest trees in tropical secondary succession

This paper emphasizes the contribution of remnant trees to the establishment of woody species during succession on abandoned fields and pastures in the Mexican rain forest area, Los Tuxtlas, Veracruz. Remnant trees, original large forest trees left in the clearings by traditional farmers will become natural perching sites for both passing and resident birds. Frugivorous birds drop or regurgitate seeds and fruits which fall under the canopies of remnant trees during their stay, thus contributing to an accumulation of species, which make these remnant trees into ‘regeneration nuclei’. The species transported into these sites belong chiefly to older stages of successional development and reach these otherwise isolated areas, counteracting the depauperization of tropical land, brought about by both intensive and extensive clearing. In a study of seven remnant trees, 29 woody species and two climbers were found, 86% of which are bird dispersed. The total number of species per tree varied from 6 to 15 and was higher under remnant trees with fruits attractive to birds. Floristic variations of the understorey as detected by detrended correspondence analysis was correlated with the relative amount of shade-tolerant primary and late secondary trees versus light dependent pioneers and early successional trees.     

Afromontane old-field vegetation: secondary succession and the return of indigenous species

South‐west Uganda primarily holds afromontane forests within three protected areas: Mgahinga Gorilla National Park, Echuya Forest Reserve and Bwindi Impenetrable National Park. All forests contain portions of old‐field vegetation. The central question of this study, then, is whether and how natural regeneration of afromontane vegetation would take place. A successional pathway consisting of nine plant communities was found for the first 2 years after cessation of agricultural use. A return of afromontane species despite of an initial dominance of neophytes, a diversification of life form spectra and a growing importance of endozoochory with time belonged to the conspicuous characteristics of this secondary succession. To obtain an insight into the role of birds and buffaloes as possible vectors for seed input, I examined their faeces with regard to germinable seeds. Both, bird faeces, as well as buffalo faeces contained germinable seeds originating from the forest flora. Thus, animal dispersal from the forest into the regenerating zones could be documented. The regeneration potential of the soil‐seed bank seems to be limited in its time scale, and only an initial regeneration capacity could be found. A further progressive succession into a secondary afromontane forest depends on an input of diaspores from undisturbed forest sites. Zoochory appears to be one of the most important dispersal mechanisms.