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...     

Soil saturation effects on forest dynamics: scaling across a southern boreal/northern hardwood landscape

Patch modeling can be used to scale-up processes to portray landscape-level dynamics. Via direct extrapolation, a heterogeneous landscape is divided into its constituent patches; dynamics are simulated on each representative patch and are weighted and aggregated to formulate the higher level response. Further extrapolation may be attained by coarsening the resolution of or lumping environmental data (e.g., climatic, edaphic, hydrologic, topographic) used to delimit a patch.Forest patterns at the southern boreal/northern hardwood transition zone are often defined by soil heterogeneity, determined primarily by the extent and duration of soil saturation. To determine how landscape-level dynamics predicted from direct extrapolation compare when coarsening soil parameters, we simulated forest dynamics for soil series representing a range of drainage classes from east- central Maine. Responses were aggregated according to the distribution of soil associations comprising a 600 ha area based on local- (1:12,000), county- (1:120,000) and state- (1:250,000) scale soil maps. At the patch level, simulated aboveground biomass accumulated more slowly in poorer draining soils. Different soil series yielded different communities comprised of species with various tolerances for soil saturation. When aggregated, removal of waterlogging caused a 20–60% increase in biomass accumulation during the first 50 years of simulation. However, this early successional increase and the maximum level of biomass accumulation over a 200 year period varied by as much as 40% depending on the geospatial data. This marked discrepancy suggests caution when extrapolating with forest patch models by coarsening parameters and demonstrates how rules used to rescale environmental data need to be evaluated for consistency.     

东北过伐林区森林景观演替分析

运用1997年二类调查数据,借助二歧指示种分类(TW INSPAN)方法,在ArcInfo的支持下,采用统一网格样点采样法,对吉林省汪清林业局金沟岭林场的森林景观的分类与演替进行了研究。结果表明:TW INSPAN通过15次划分,把整个金沟岭森林划分为7种经营景观类型,演替阶段从低到高依次为:人工纯林景观、榆杂林景观、杨桦林景观、阔叶混交林景观、针阔混交林景观、云冷落针叶混交林景观、阔叶红松林景观。同时,也说明TW INSPAN不仅可以有效地进行景观分类,还能反映景观类型在某一时空的梯度关系。     

陕北黄土丘陵区撂荒演替中期群落比较异质性研究

对陕北黄土丘陵区撂荒演替中期6块样地进行了群落间异质性和群落异质性分析。结果表明,群落间异质性与环境因素差异多数为正相关,说明环境对撂荒演替中期群落组成与结构起到了一定的塑造作用,典型相关分析进一步表明群落间异质性有84.6%是由环境差异引起的,其中土壤全磷含量与群落间组成异质性、土壤水分与群落结构异质性有较强的正相关关系,说明土壤磷营养对撂荒演替中期群落组成有较大的影响,而土壤水分是影响植物生长和群落结构的重要因素,因此在对撂荒7~15年的耕地进行恢复与重建应注意磷肥的施用和节水、保水措施。     

植被恢复演替初期对模拟降雨产流特征的影响

利用模拟降雨装置,研究了演替恢复初期不同植被覆盖以及不同处理下坡面降雨的产流过程和人渗率。实验研究结果表明,植被演替开始之初,由于地表土壤的土质比较疏松,土壤的人渗率比较大。随着植被演替的进行,土壤中有机质等物质的逐渐累积,土壤的理化性质发生了变化,土壤的人渗特征也随之降低。剪草降雨小区的实验研究结果说明,在降雨的初期,土壤的人渗性能相对较低,随着实验的进行,在雨滴的打击下,部分结皮被破坏,土壤的人渗率也随之增大。说明地表生物结皮的存在,降低了土壤的人渗性能。采取适当的措施破坏地表生物结皮,有利于提高土壤的人渗性能,增加干旱半干旱地区对降雨的利用程度。     

日本冲绳岛琉球松林台风干扰后的群落特点

为阐述亚热带地区琉球松林受到干扰后的演替规律,就日本冲绳地区琉球松人工林在强台风干扰后,林分结构和树种组成特点进行了调查分析。结果表明,琉球松林经台风干扰后演替形成两种群落类型,即琉球松-峨嵋木荷群落和琉球松-峨嵋木荷-蕨类群落;两者在林分结构和树种组成特点方面差异明显。琉球松-峨嵋木荷群落中,出现乔灌树种26种(DBH≥3．0cm),树种多样性指数为2．55,林下植被特别是草本层盖度低,没有蕨类植物分布。而琉球松-峨嵋木荷-蕨类群落中,出现乔灌树种33种,树种多样性指数为3．51,林下植被特别是草本层发育较好,并有大量蕨类植物分布,其盖度达55％。此外,经受干扰的琉球松林出现了大量的较耐荫的常绿阔叶树种,尤其是山茶科和樟科的树种,而没有出现本地天然常绿阔叶林的优势树种壳斗科的栲类(Castanopsis spp.)。充分说明强台风干扰促进了琉球松林向常绿阔叶林演替。     

朝阳地区植被演替及封育类型

朝阳地区在200年前林草茂盛，后经乱砍滥伐，使森林受到严重摧残，生态环境发生急剧变化，在闪生演替过程中，决定次生演替性质，方向和速度仍然是人为活动，由于环境的破坏程度不同，不同立地反应了次生演替的不同阶段，如果消除破坏因素，命名适生区生境的群落得以复生，依据更新 树种与立地相关关系，通过数量化理论分析，影响更新主导因子有坡向，土厚，坡位，母岩和海拔，按立地与更新树种双因子法划分出7种封育类型。     

Vegetation succession process induced by reforestation in erosion areas

Reforestation is one of the most important and efficient measures of water and soil conservation. Based on field investigations in the Shangyang Soil Conservation and Reforestation Station in Huizhou, Guangdong Province, China, we studied the variation in vegetation development, vegetation succession processes and soil erosion. The regional vegetation consists mainly of monsoon evergreen broad-leaved forests (MEBF). The area was deforested and became a denuded hill area with extremely high soil erosion in the 1960s and 1970s. Then, the area was closed in order to allow recovery of the vegetation. Under natural conditions the vegetation development and succession processes were slow during which soil erosion and strong sunshine and evaporation slowed down the development of the vegetation. About 25 years later, the vegetation cover was still merely 35% or so. The dominant vegetation types were heliophilous herbage and shrubs which formed a poorly developed shrub-herbage community and erosion remained high. In contrast, reforestation with selected tree species dramatically speeded up the vegetation succession process. About 12 years after reforestation, vegetation cover of the Acacia auriculiformis plantations in the Shangyang Station was 90% and erosion was under control. After 23 years, understory vegetation, consisting of indigenous species, had developed in the plantations. The planted trees and naturally developing herbage, shrubs, bamboo, local trees and liana formed a complex vegetation community in three layers. It will take 60 years for the vegetation to succeed from bare land to a secondary growth forest under natural conditions. Reforestation may speed up the vegetation succession process. The time may be reduced to 20 years. Reforestation is the most effective measure of vegetation restoration and erosion control in this area. __________ Translated from Acta Ecologica Sinica, 2006, 26(8): 2558–2565 [译自: 生态学报]     

Fuelwood Resources and Forest Regeneration on Fallow Land in Uganda

Abstract

East African forests have been largely converted to agriculture. The remaining forests hold many endangered species but are threatened by the heavy local demand for fuelwood. Here we evaluate fallow land in western Uganda as an alternate fuel source to diverse forests. We quantify the regeneration process on fallows, calculate tree bio-mass increases, and measure grass and woody herb biomass over 44 months. The biomass values we measured were typical or slightly below the average from 11 studies elsewhere in the tropics. Variation in biomass between our neighboring study sites exceeded that between sites on different continents, indicating the sensitivity of vegetation regeneration to local land use. Tree regeneration was extremely slow (0.46 g/m²/year); however, the woody herbs and grasses on a 4 year old fallow of ～0.5 ha can provide much of a family's domestic fuel. Fallow land is generally abundant in western Uganda and can partially alleviate pressure on forests for domestic fuels. Fallows cannot however provide the trees demanded by charcoal, brick, and gin manufacturers. In the future, conserving forests while meeting fuelwood demands will require improving local land tenure security, enhancing the productivity of cultivated and abandoned land, promoting more efficient stoves, stills and kilns, and curtailing illicit, inefficient charcoal manufacture.     

鄂东北枫香林更新演替研究

实地调查了红安天台山的枫香(Liquidambar formosana)纯林、枫香-锐齿槲栎(Quercus aliena var.acuteserrata Maxim)等阔叶混交林、枫香-马尾松(Pinus massoniana Lamb.)针阔混交林3种森林类型的12个样地,分别选用特卡钦科法、分层频度法评价各森林类型的更新等级和演替趋势。结果表明,3种森林群落的优势树种更新较差,幼苗数量比较少,主要受郁闭度、坡向、坡度和坡位的影响。阔叶纯林(枫香林)将演替为以枫香、锐齿槲栎和化香(Platycarya strobilacea Sieb.et Zucc.)为主要组成树种的阔叶混交林;以枫香为主的阔叶混交林在一定时期内将演替为阔叶混交林;而针阔混交林将演替为阔叶混交林。