拖拉机集材对林地土壤的影响

本文从环境保护的观点出发.分析了拖拉机集材造成的林地土壤压实、水土流失。并对集材前后迹地土壤营养成份流换情况进行对比。结果表明,拖拉机集材对森林生态环境破坏较为严重。不符合生态效益对林业生产的要求。     

林火对土壤的热量状况的影响

根据营林目的不同,林业用火可分控制火烧(control burning)和规定火烧(prescribed bu-rning)。前者指把采伐剩余物或其它零散的可燃物等散铺在林地上或在林地堆积成带晒干后点烧,许多国家在造林前清理山场常用此方法,在我国南方林区称之为炼山。后者则指用火烧除林下活的植被或凋落物,以降低火灾危险性,美国、加拿大、澳大利亚及我国东北林区等广泛应用此法。在火烧过程中,及火后相当长时间内土壤温度的变化,对土壤肥力状况有着显著的影响,而影响的程度取决于林火对土壤热量状况的影响。林火通过直接烧毁地上部分和地面有机物及对土壤灼烧而影响土壤的热量状况。热在森林土壤中传导状况取决于土壤的比热、导热系数、土壤导温     

火干扰对塔河白桦落叶松林土壤化学性质的短期影响

火一直是我国北方森林的重要干扰因子,在气候变化影响下,其干扰作用进一步增强。该文对大兴安岭地区代表性森林白桦落叶松林不同强度火烧迹地经过1个生长季后土壤化学性质进行了调查分析。结果表明:不同火强度干扰后的土壤化学性质常呈现显著性差异,火强度对扰动程度具有重要影响,是决定扰动程度的关键因子。火干扰提高了土壤的p H值,促进了养分回归,提高了土壤养分含量。白桦落叶松林地土壤p H值随火干扰强度的增加而升高;土壤全氮、全磷、全钾平均含量中强度火干扰林地高强度火干扰林地低强度火干扰林地无火对照样地;土壤铵态氮含量随林火强度的增强而减少,但火干扰提高了土壤硝态氮含量,强度越高硝态氮含量增加的越多;白桦落叶松林土壤有效磷平均含量中强度火干扰林地低强度火干扰林地高强度火干扰林地无火对照样地,土壤速效钾平均含量中强度火干扰林地高强度火干扰林地低强度火干扰林地无火对照样地。     

鄱阳湖流域水土流失与森林生态环境控制管理对策

江西省水土流失集中分布于鄱阳湖水系的"五河"及其支流流域,流域水土流失的主要来源分别是坡耕地、工业生产建设废弃物,尤其以林业用地水土流失最为严重。森林资源年龄结构比例失调,林地逆转流失严重,森林利用与恢复方式单一,致使水土流失控制所需要的森林生态防护功能供给不足。为了遏止水土流失,必须调整人工林单一树种结构,重建防护功能较高的复合型森林生态系统,同时调整和改革现行不合理的森林经营管理模式,变革坡耕地土地利用方式,实施全流域坡耕地退耕还林生态恢复工程。     

森林采伐作业中防止水土流失的几个问题

森林工业对环境影响最大,破坏最快是在采伐的时候。森林采伐严重而迅速地破坏森林的生态系。由于采伐时的不注意,使林地毁坏,肥力减退,水道堵塞。对林业工作者来说,主要的是采伐对水土保持的影响问题。作业计划务须考虑涨水、水土流失以及必然出现的沉积的后果。采伐方式应根据森林植被的状态、土壤类型、地形和气候条件来确定。一般说来,采伐后迹地上的水流量会立即增加。林地破坏越大,沼泽化越严重,     

南方国有林地资源管理问题及其对策探讨

林地是森林资源的重要组成部分,是林业生产的基础。目前,南方国有林地各种形式被侵占的情况愈来愈严重。本文通过对江西省景德镇市枫树山林场林地资源管理现状的分析,讨论南方国有林地资源的管理问题及其对策。     

营林用火对油茶林地土壤养分的影响

营林用火可促使林地养分循环与再分配,维护森林土壤生态平衡。通过对比分析不同燃烧时间下的林地土壤养分、p H值及油茶产量,研究营林用火对油茶林土壤养分及其产量的影响。结果表明:(1)用火后,油茶林土壤中的氮、磷、钾、有机质和土壤p H值均有提高,土壤养分提高幅度较大的用火月份主要集中在3月、5月和9月;(2)用火时间对土壤养分的影响差异显著,其中不同用火时间土壤养分的增加幅度排序为90 min60 min30 min120 min;(3)用火对5~10 cm全氮、有机质和p H值影响最大,而对10~20 cm的有效磷和有效钾影响最大;(4)用火效果差异明显,不同用火时间下的油茶产量和产值排序为90 min60 min30 min120 min,其中用火时间90 min的油茶产量为2 423 kg/hm2,产值为44 098.6元/hm2。     

学习长汀经验 弘扬长汀精神

7月21日,全国林业厅局长会议在福建省长汀县举行。会上,全国绿化委员会、国家林业局授予长汀县"全国生态文明建设和现代林业建设示范县"称号。国家副主席习近平曾指出:长汀县曾是我国南方红壤区水土流失最严重的县份之一,经过10余年的艰辛努力,水土流失治理和生态保护建设取得成效,但仍面临艰巨的任务。长汀县水土流失治理正处在一个十分重要的节点上,进则全胜,不进则退,应进一步加大支持力度。要总结长汀经验,推动全国水土流失治理工作。     

日本林业发展的森林组合策略——战后日本林业的发展及其启示(十)

正"二战"后的日本,林业生产的基本情况与我国今天的南方集体林区颇为类似:民有林为主,人多地少,规模较小,林地破碎,分散经营。但战后日本的森林资源却在较短的时期内得到了快速增长,森林覆盖率、生态公益林面积占林地面积比重、林分单位面积蓄积量和林业就业人员平均收入等诸多主要指标居世界前列,并成功实现了林业现代化。这些成就的取得与日本林业合作组织     

毛竹林地土壤水土流失的初步研究

采用人工模拟降雨装置,对毛竹林地土壤流失进行了试验,结果表明:林地坡度是影响林地土壤流失的主要因子,坡度在30耙陨鲜?极易造成林地土壤冲刷;地表覆盖能有效地降低地表径流中的泥沙含量;大雨、陡坡、全垦造成的水土流失非常严重.     

火干扰对森林水文的影响

在森林生态系统中 ,火是一种相当普遍的自然现象 ,森林火灾和森林水文二者有着密切的关系。森林火灾对水的影响是间接的 ,主要表现为火烧后植被、地被物、土壤以及生态环境的改变影响水分循环过程、水质、水生生物等方面。火对水文的影响有大有小 ,它取决于火强度和频度。轻度野火或计划火烧对水文可能不产生明显影响 ,但是 ,频繁的或严重的野火却可以导致乱砍滥伐所造成的类似水文变化     

林火与土壤肥力

本文综述了世界上一些国家有关林火对土壤物理性质、化学性质、土壤微生物活性的影响,指出林火对土壤肥力影响受火强度、火持续时间、可燃物种类和数量、土壤性质、降雨状况及植被恢复状况等因素的影响。在我国南方林区用炼山方式清理迹地,对地力长期维持不利。建议对皆伐火烧地采用人工促进天然更新或林农复合经营方法,以维持地力,促进林木持续生长。     

李子口径流小区不同植被条件下降雨对土壤侵蚀的影响研究

采用径流小区实验的方法,在李子口小流域设立了6个不同植被类型的径流小区,研究径流小区不同植被条件下降雨对土壤侵蚀的影响,结果如下:(1)不同植被条件下,降雨对土壤侵蚀的影响可表现为撂荒地小区>农耕地小区>林地小区,降雨对林地的土壤侵蚀弱,林地对当地水土的保持能力强,最适合作为当地水土保持的植物措施。(2)总体上,6个径流小区的降雨量、降雨侵蚀力与地表径流量、径流深、土壤流失量之间的相关性均表现为显著正相关的关系,表明降雨对当地土壤侵蚀作用强,需重点防护。研究揭示了研究区降雨与土壤侵蚀的相关性,比较了不同植被条件下降雨对土壤侵蚀的影响,为水土保持的相关研究提供参考与借鉴。     

计划烧除引起水土流失的定量研究

首次在国内对计划烧除林地水土流失量进行了定位研究,结果显示计划烧除林地土壤侵蚀强度因坡度变陡而增加,坡度23的试验区为69．5t／(km·a),对照为52．6t／(km·a);坡度33“的试验区为104．7t／(km·a),对照为101．8t／(km·a)。计划烧除林地的土壤侵蚀量远远低干200t／(km·a)这个最低允许流失量标准。可以认为,在林内开展计划烧除所引起的水土流失量是很微弱的。周期性地开展计划烧除产生的生态负效应对环境质量的影响不显著。为了降低森林的燃烧性,大幅度减少森林火灾,积极开展计划烧除不仅必要,而且可行。     

Historic and current fire regimes in the Great Xing’an Mountains,northeastern China: Implications for long-term forest management

Understanding both historic and current fire regimes is indispensable to sustainable forest landscape management. In this paper, we use a spatially explicit landscape simulation model, LANDIS, to simulate historic and current fire regimes in the Great Xing’an Mountains, in northeastern China. We analyzed fire frequency, fire size, fire intensity, and spatial pattern of burnt patches. Our simulated results show that fire frequency under the current fire scenario is lower than under the historic fire scenario; total area burnt is larger with lower fire intensity under the historic fire scenario, and smaller with higher fire intensity under the current fire scenario. We also found most areas were burned by high intensity fires under the current fire scenario, but by low to moderate fires under the historic fire scenario. Burnt patches exhibit a different pattern between the two simulation scenarios. Large patches burnt by high intensity class fires dominate the landscape under the current fire scenario, and under historic fire scenario, patches burnt by low to moderate fire intensity fires have relatively larger size than those burnt by high intensity fires. Based on these simulated results, we suggest that prescribed burning or coarse woody debris reduction should be incorporated into forest management plans in this region, especially on north-facing slopes. Tree planting may be a better management option on these severely burned areas whereas prescribed burning after small area selective cutting, retaining dispersed seed trees, may be a sound forest management alternative in areas except for the severely burned patches.     

混农林业对石漠化地区土壤环境的影响及其应用

土壤环境变化是恢复生态学研究的重要内容之一,加强混农林的立体优化配置,有利于控制水土流失、改善土壤环境质量和提高生态脆弱区的生态和经济效益。文中系统总结混农林业对石漠化地区土壤水分、养分、生物特征的影响,阐明在石漠化极端脆弱生态环境条件下,林木与农作物存在的水肥竞争以及复合农田中树龄较小时对土壤生物活性的抑制作用,进一步从石漠化地区土壤环境角度对混农林业的水分利用策略、乡土树种的选择搭配、有益土壤生物的应用等方面提出建议,以期为喀斯特石漠化地区提高土地生产力、控制水土流失、发展立体生态农业等提供参考。     

Study on Function of Vegetation''''s Preventing Soil Erosion in Small Watershed of the Loess Area

This paper analyzes the function of preventing soil erosion of the different woodlands according to a long-term fixed-position observation, and points out that the steep slope plantation of uncontrolled measures for soil and water conservation is apt to produce sediment Forestland has very strong effect in soil and water conservation when the biomass of arbor in the hillslope is over 1 4.51t/ha. Through analyzing the function of soil and water conservation about forestland (arbor, bush and the mixed wood of arbor and bush), it can be known that if the high forest coverage reaches 40%, forests will provide better protective function. To vegetation under forest, litter layer, herb and sparse forest land which do not suffer destruction from human beings, they all have good function in preventing erosion, and the amount of soil loss is far less than the tolerance of soil erosion. At the same time, when vegetation coverage and biomass are in an appropriate state, they will have powerful protective function.     

Distinctiveness of wildfire effects on soil erosion in south-east Australian eucalypt forests assessed in a global context

The premise of this paper is that continued improvement in the understanding of wildfire impacts on soil erosion and better prediction of resulting hazards can be best achieved by adopting a concept of global regional variants and endemic factors that distinguish some regions in terms of post-fire erosion characteristics. The need for such an approach is exemplified here based on the fire-prone eucalypt forests in south-east Australia. Wildfire effects on vegetation, fauna, soil erodibility and erosion in this environment are evaluated and placed in the context of the global state-of-the-art for forest environments. In addition to expected variation resulting from, for example, geology, topography and climate of the area, it is argued that a distinctive post-fire behaviour is caused in these eucalypt forests by the interaction between specific characteristics of the vegetation, litter, soil properties, faunal activity and micro-scale surface features. Soil erosion limited only by post-fire rainfall intensity and quantity, or until bedrock is exposed, might be expected after wildfire on steep slopes in these forests given the non-cohesive character of the often sandy soils and their universally water repellent character. That this scenario is not realised, except possibly under extreme rainfall conditions, which rarely occur during the vulnerable post-fire period, can be attributed to a unique suite of features that disrupt or provide sinks for overland flow, bind the loose in situ soil and trap mobilised sediment. These include mats of fine roots, litter dam–microterrace complexes and faunal activity by small mammals and ants. In combination, these characteristics reduce post-fire hillslope-channel sediment transfer, at least under light to moderate intensity rainfall typical of post-fire periods following recent wildfires. Evidence is discussed suggesting that the long-term geomorphological role of wildfires in south-east Australia may be of relatively minor importance and confined largely to enhanced weathering of exposed outcrops and redistribution of soil across existing erosional and depositional landforms. The soil fertility and downstream water quality implications of widespread transfer of topsoil to watercourses resulting from frequent, often severe wildfires are nevertheless significant.     

干旱半干旱区山地森林的水分调节功能

处于中国西北干旱半干旱区的山地森林以独特的水文作用成9为山前平原及川区绿洲生态经济系统稳定发展的基础。以典型山地森林祁连山水源涵养林的主要群落青海云杉林为例，通过长期定位观测研究森林调节小气候的水文规律及功能，揭示了森林对降水的分配调节作用。森林通过林冠层截留降水使到达林内的降水量减少、强度降低、雨滴对地面的冲击减弱，避免林内发生地表径流引起水土流失；森林通过林冠层遮蔽减弱太阳辐射降低了林内土壤蒸发，保持林内湿度较高、土壤含有较多水分，为喜湿耐荫植物生长发育创造了适宜的阴湿环境，并提供了充足的水分条件；森林的蒸腾发散使同一高度林区上空的湿度比草地或裸地高，改变了局地大气环流，为降水形成准备了物质条件，起到了增加林区降水的作用。     

Climate and recent fire history affect fuel loads in Eucalyptus forests: Implications for fire management in a changing climate

Predicted changes to global climates are expected to affect natural fire regimes. Many studies suggest that the impact of these effects could be minimised by reducing fuel loads through prescribed burning. Fuel loads are dynamic and are affected by a range of factors including fire and climate. In this study, we use a 22-year dataset to examine the relative influence of climate and fire history on rates of litterfall and decomposition, and hence fuel loads, in a coastal Eucalypt forest in south-eastern Australia. Litterfall and decomposition were both affected by temperature, recent rainfall and fire history variables. Over the study period prescribed burning immediately reduced fuel loads, with fuel loads reaching pre-burn levels within 3 years of a fire. Modelling fuel loads under predicted climate change scenarios for 2070 suggests that while fuel loads are reduced, the levels are not significantly lower than those recorded in the study. Based on these predictions it is unlikely that the role or value of prescribed burning in these forests will change under the scenarios tested in this study.