Soil phosphorus fractions and their availability over natural succession from clear-cut of a mixed broadleaved and Korean pine forest in northeast ChinaOA

To assess phosphorus(P) status of forest soil under naturally restored vegetation, P fractions in the 10-cm soil layer were quantified at different successional stages on the clear-cut site of mixed broadleaved and Korean pine forest. Four communities of shrub, softwood broad-leaved forest, softwood and hardwood broad-leaved forest, and hardwood broad-leaved forest represented different successional stages. A soil sample from a primary broad-leaved and Korean pine stand was the control. A sequen...     

松材线虫病疫木不同伐除方式对森林植物群落演替的影响

采用标准地调查法,对不同立地条件下松材线虫病除治迹地生态系统的植物种类丰富度、密度、多样性指数、均匀度指数及垂直结构情况进行调查和分析。结果表明:立地条件的差异和疫木不同采伐方式对植物群落次生演替的进程和方向都有不同程度的影响。立地条件较好,无论是皆伐、择伐还是不采伐,除治迹地植物群落乔木层和灌木层较受害前纯林的种类丰富度和多样性指数都有一定程度的增加;而立地条件较差的,经皆伐后,植物群落的种类丰富度和多样性指数不仅没有增加,反而降至极低,原有松林群落向灌丛方向退化。     

广东省红树林植物群落分布与演替分析

文章介绍了广东省红树林的资源现状，包括红树林的种类、群落类型、数量、分布、群落演替类型及生长环境等；分析了广东省红树林植物群落的分布规律及广东红树林植物群落的4个演替阶段；指出红树林演替系列是与生态序列相一致的演替特征。     

封山育林是恢复和重建晋西黄土高原森林植被的重要途径

论述了晋西黄土高原封山育林的必要性、理论依据及可行性。分析了不同时期弃耕地和封禁小流域的植物演替和植被恢复规律。在黄土弃耕地上植物群落演替规律为：弃耕后,15a-20a为草本植物群落阶段;21a-25a可形成灌木群落;26a-30a能达到较成熟、稳定的灌丛群落;30年后,开始形成乔木林。黄土残塬沟壑区封禁小流域植被恢复情况为：经过12a,木本植物的种类达到了41种,分属于16科34属,其种源来源于周围残存的次生林。总结了封山育林的效果。     

Effect of vegetation restoration on ant nest‐building activities following mobile dune stabilization in the Horqin Sandy land,Northern China

Measurements of the density and characteristics (size and height) of ant mounds were carried out on mobile, semi‐mobile, semi‐fixed and fixed dunes in the Horqin Sandy Land, Northern China. The relationships between the distribution of ant mounds and the plant community (abundance and cover) were investigated, for areas within and across the dune stages. Changes in spatial pattern of ant mounds were also analysed following mobile dune stabilization. The results showed no ant mounds on mobile dunes; the mound density was significantly higher on fixed dunes than on semi‐fixed or semi‐mobile dunes. The mound density depended on plant density and cover across all dune stages, but not within any dune stage. The mound diameter increased but the mound height decreased from semi‐mobile dunes to fixed dunes. However, the mound diameter and height were not related to plant cover and density within any stabilization stage or across all dune stages. The spatial pattern of ant mounds tended to change from more clumped (semi‐mobile and semi‐fixed dunes) to less clumped and approached a random pattern (fixed dunes) along the dune stabilization gradient, which was related to the changing vegetation pattern during succession. Although the quantification of the number of ant species present was not attempted on each dune, the observed differences in ant colour and size suggest at least eight species were present. Fixed dunes were more attractive for different kinds of ant species, but the mound distribution exhibited a more random pattern with more continuous vegetation. Thus, different environmental conditions, especially in terms of the plant communities present at different dune stages, affected the activities and behaviour of the ants (including the distribution of mounds), but did not affect mound size and height. Copyright © 2009 John Wiley & Sons, Ltd.     

Physical extent,frequency, and intensity of phosphatase activity varies on soil profiles across a Douglas-fir chronosequence

In forest soils, the availability of phosphate is largely dependent on phosphatase activity. We used soil imprinting to compare in situ activity and fine-scale distribution of phosphatase on soil profiles located across forest chronosequences of four age classes young (5–6 yrs), canopy closure (24–30 yrs), stem exclusion (61–71 yrs), and older (90–103 yrs) of mixed Douglas-fir/paper birch stands regenerated after fire or clearcutting in southern interior British Columbia, Canada. Chromatography paper treated with a mixture of substrate and colorimetric reagent was applied directly to vertical soil surfaces, accessed through root windows. Stands older than 61 years had both the highest level of in situ phosphatase activity and larger, more intense regions of activity. Bray-extractable phosphorus was negatively related to imprintable phosphatase activity. We compared the changes in phosphatase activity with differences in the ectomycorrhizal fungal (EMF) community that had been documented previously in the same stands. Of 84 ectomycorrhizal fungi found on roots in at least two of the stand-age classes, eight taxa were positively correlated and one taxon (Rhizopogon vinicolor/vesiculosus) negatively correlated with high phosphatase activity. The frequency of three taxa appeared to be positively correlated with larger areas of activity on the soil profiles. By using an imprinting approach, this study was able to demonstrate, for the first time, that in situ phosphatase activity and physical attributes of that activity (i.e., number, size, and relative rates of each area of activity) were related to concentrations of soil nutrients and with the frequency of individual ectomycorrhizal fungi.     

Lichens and bryophytes on Eucalyptus obliqua in Tasmania: management implications in production forests

Thirty lichen and 25 bryophyte species have been recorded from the buttresses of Eucalyptus obliqua, the dominant tree in wet sclerophyll forest at the Warra Long-Term Ecological Research Site in southern Tasmania. The flora, characterised by four major associations, is very distinctive, containing a relatively high number of eucalypt specialists, particularly among the lichens. A general trend towards increasing species richness with increasing tree diameter is apparent and is attributed mainly to increasing habitat diversity on the buttresses. The increase in species occurs without the loss of pioneers; thus succession involves addition rather than replacement of species. The relationships between epiphytes, tree age and forest age are complicated by the periodic occurrence of fires in the forest. Nevertheless, potential oldgrowth indicators are identified and the possible effects of current silvicultural practices on the conservation of the species are discussed.     

Reciprocal adjustments between landforms and living organisms: Extended geomorphic evolutionary insights

Whilst biological organisms adapt to the environment, earth surface processes and landforms evolve as a result of physicochemical processes, and as the result of the activity of certain living organisms defined as ‘ecosystem engineers’. The importance of long- and short-term impacts on geomorphic structures and processes by ecosystem engineers appears to be underestimated. Recent recognition of complex abiotic–biotic feedbacks in nature has resulted in a convergence of approaches in ecology and geomorphology. Present biogeomorphic knowledge supports the hypothesis that abiotic–biotic feedbacks create characteristic modulated patterns of earth surface landforms, adjusting according to biological evolution in the long term and to ecological succession in the short term. In this context, natural selection of organisms and ecological successions are considered to have the potential, in some cases, for extension to the physical world, including earth surface landforms. This perspective aims to contribute to the disruption of the ‘classical’ dichotomy between abiotic–biotic compartments because it emphasizes reciprocal adjustments (i.e., feedback mechanisms) between living organisms and abiotic environment dynamics. The extended evolutionary perspective, that is intended to feed back to ecology and evolutionary biology, indicates the potential for change in our deep understanding of geomorphology to reflect evolutionary and ecological succession theories.