Phosphorus release from forest harvesting on an upland blanket peat catchment

The aim of this study was to investigate the release of phosphorus (P) to receiving waters resulting from harvesting 34-year-old lodgepole pine trees in an upland peat catchment. The study site was within a 25.3-hectare (ha) area, and was drained by a stream that received flows from ploughed furrows, mainly, via collector drains, and discharged directly to the salmonid Shrahrevagh River, Burrishoole, Co. Mayo, Ireland. The study site was divided into two parts: the upstream part was left intact and the downstream part was harvested in early Autumn 2005 following implementation of forest guidelines. Good management practices such as proper use of brash mats and harvesting only in dry weather were implemented. Two instrumented stations were established – one just upstream (US) and the other just downstream (DS) of the clearfelled area. The measurement of P concentrations at the two stations commenced in May 2005, two months before the harvesting started. The daily mean P concentration at the DS station increased from about 6 μg L⁻¹ of total reactive phosphorus (TRP) during pre-clearfelling to 429 μg L⁻¹ in August 2006. By October 2009, four years after clearfelling, the P concentrations at the DS station had returned to pre-clearfelling levels. In the first three years after harvesting, up to 5.15 kg ha⁻¹ of TRP was released from the harvested catchment to the receiving water; in the second year alone, 2.3 kg ha⁻¹ of TRP was released. Linear regression can be used to describe the relationship between TRP load and water discharge. About 80% of the total phosphorus (TP) in the study stream was soluble and more than 70% of the P release occurred in storm events, indicating that traditional buffer strips with widths of 15–20 m might not be efficient for P immobilization. The P concentrations were affected by antecedent weather conditions and highest concentrations occurred during storm events following prolonged drought periods. The water extractable phosphorus (WEP) contents in the soil were significantly higher below windrow/brash material than in brash-free areas, and whole-tree harvesting should be studied as one of the means to decrease P export from blanket peats.     

Wildfire and salvage harvesting effects on runoff generation and sediment exports from radiata pine and eucalypt forest catchments, south-eastern Australia

This study examined the effect of wildfire and salvage harvesting on runoff generation and sediment exports from three small forest catchments in south-eastern Australia. In 2006, wildfire burnt a radiata pine catchment and two adjacent natural eucalypt forest catchments which formed part of a long-term hydrological research project. Subsequently, only the pine plantation catchment was salvage harvested. The combined effect of fire and salvage harvesting in the pine catchment caused a substantial increase in runoff compared to the burnt eucalypt forest catchments and pre-fire conditions, particularly in response to high intensity, short duration summer storms. Post-fire maximum suspended sediment concentrations from fixed-interval sampling greatly exceeded pre-fire values for both eucalypt and pine catchments, while sediment (suspended and bedload) exported from the pine catchment exceeded each of the eucalypt catchments by a minimum of 180 and 33 times. However, the export increase was probably closer to 320 and 71 times based on a survey of eroded channels in the pine catchment combined with measured post-survey exports. Notably, seven summer storm events accounted for approximately 80% of the pine catchment sediment yield. Hillslope process measurements indicated that the highest runoff velocities occurred in log drag-lines formed by cable harvesting, while soil water repellency was more extensive in the harvested pine catchment than in the adjacent eucalypt catchment. The latter effect probably resulted from higher burn severity in the pines combined with reduced soil moisture due to less shading after harvesting. Runoff modelling indicated that the log drag-lines acted as an extension to the drainage network and increased peak flows at the harvested catchment outlet by 48% for a high intensity summer storm event, while substantial reductions in modelled runoff were achieved through increasing the hillslope surface roughness coefficient. It is recommended that post-fire salvage operations should avoid the formation of log drag-lines when using cable harvest techniques and maximise surface cover to limit increases to runoff, erosion and catchment sediment exports.     

Topography and biomass characteristics of a forested catchment in the Northern Appalachians

Using data from 241 plots the variability of site index and biomass in a forested catchment was represented by the distribution of the appropriate differences between plot values and the average values for the whole catchment period. Relationships were derived that express the above differences as functions of azimuth and inclination of forest sites. They yield highest site index values for east-facing slopes and highest biomass values for north-facing slopes. The west-facing slopes are characterized by minimum values of site index and biomass. On west-facing slopes site index decreases when slope inclination increases; on east- and north-facing slopes site index increases with inclination. On south-facing slopes biomass decreases when slope inclination increases; on north-facing slopes biomass increases with slope inclination.For partial areas of the catchment, the difference between computed and observed site index appears between 3.5% and 6.9% of its average value for the whole catchment. The appropriate difference for biomass is from 12.2% of 35.6% of its average value for the whole catchment. Both differences reach maximum values in the northern part of the catchment that is characterized by greater stoniness.     

Limnological effects on a first order stream after wood ash application to a boreal forest catchment in Bispgården,Sweden

In Sweden, whole tree harvest is common practice, possibly leading to the depletion of mineral nutrients. Furthermore, the increased use of forestry residues for heat production has caused an increasingly growing amount of by-product consisting of wood ash. Therefore, the Swedish Forest Agency has recommended wood ash application (WAA) to replace the mineral nutrients removed by whole tree harvesting, as well as a means to mitigate the acidification of boreal forests and surface waters. In a multidisciplinary study during 2003–2006 in Bispgården (Sweden), we have investigated the limnological effects on a first order stream after WAA (conducted in 2004; 3000 kg ha⁻¹) to a 50-ha forested catchment. In general, no significant effects on an annual basis were found for acidification parameters, such as pH, alkalinity and toxic forms of aluminum (Al). There was, however, evidence of an increased pH during the spring flood, accompanied by a simultaneous decrease in the frequency of low pH-values (<5.6). Moreover, alkalinity increased in the years 2005 and 2006 compared to that of 2003, although the increase in 2006 was not statistically different from that in 2005 or 2003. High concentrations of Al repeatedly occurred in the stream, and the WAA did not affect the frequencies of high concentrations of toxic Al forms (>50 μg l⁻¹). The benthic diatom community did not change as a result of the wood ash treatment and the diatom-based index IPS (Indice de PulluoSensibilité) indicated no nutrient enrichment or organic pollution of the stream water. There were, however, indices of elevated concentrations of potassium (K) in the aquatic moss Fontinalis antipyretica and in leaves from Alder (Alnus incana). We conclude that wood ash treatment of a forested catchment with the dose and form of ash applied in this study did not modify the freshwater ecosystem of a first order stream.     

Impacts of logging residue and stump removal on nitrogen export to a stream: A modelling approach

Abstract

The use of forest chips for energy can decrease net carbon emissions to the atmosphere, but harvesting logging residues and stumps may have adverse effects on the environment, including changes in nutrient export to water-bodies. The aim of this study was, with the aid of a computer model, to simulate the effects of logging residue and stump removal on nitrogen (N) export from a clear-cut area to a stream. A spatially semi-distributed FEMMA ecosystem model (tool for Forestry Environmental Management) was used to simulate N export from a catchment subject to clear-cutting and four different scenarios of logging residue and stump removal. These scenarios were compared with a conventional clear-cutting scenario, where the logging residues were left on site. Simulations suggested that the logging residue recovery does not decrease N export to the stream. In the model this was explained by a decrease in microbial immobilization, which in the case of conventional clear-cutting reduces net release of N in decomposition and mitigates the export of N. The decrease in immobilization is directly related to the removal of the woody debris from the site. Simulations suggested that harvesting of logging residues in low atmospheric N-deposition areas is not an effective strategy for reducing N loads in water-bodies.     

The long-term effects of catchment liming and reduced sulphur deposition on forest soils and runoff chemistry in southwest Sweden

Whole catchment liming or forest liming has been proposed and implemented as a countermeasure to the effects of elevated sulphur deposition. Since the end of the 1980s the Swedish Forest Agency has undertaken experimental forest liming experiments in selected catchments in southern Sweden. These studies were with low doses (3 tonnes ha⁻¹) of lime (CaCO₃) and dolomite (CaMg(CO₃)₂). Data from both soil samples and stream water samples have been collected for the 16 years following treatment. The stream data has been complemented with data from untreated catchments, from the Swedish monitoring stream network. Significant differences due to treatment were seen for Ca, cation exchange capacity (CEC) and base saturation (BS) in the humus layer, none of these variables showed a statistically significant change in the mineral soil due to treatment alone. Soil samples from both the treated and untreated sites showed temporal changes in both the humus layer and the mineral soils with increases in pH, Ca and CEC and decreases in BS and Al which were independent of treatment. A combination of treatment and time, gave significant changes in BS and TA down to 10 cm in the mineral soil. In the stream water samples no statistically significant differences were observed between treated and untreated sites. Regardless of treatment, the streams exhibited a general pattern of declining concentrations of SO₄, Ca, sum of base cations (BC) and increasing acid neutralizing capacity (ANC). In summary, the application of a low dose of lime (3 tonnes ha⁻¹) did not result in significant changes in surface water chemistry in the study catchments and changes in soil chemistry were mainly restricted to the humus layer during the 16 years following treatment. The natural recovery, as a result of reductions in sulphur deposition, dominated the effects and was clearly seen in both the treated and untreated study sites. MAGIC simulations indicate that this recovery will continue in the coming decades.     

吉林省长白山区侵蚀沟集水区林业工程治理的研究

采用林业工程方法治理侵蚀沟集水区,森林覆盖率可由原来的3.0%～11.7%提高到37.1%～93.5%,土壤侵蚀模数由原来的3 352～4 048 t·km-2.a-1下降到1 708～2 148 t·km-2.a-1,下降51%～72%,径流系数减少48.4%,土壤蓄水量增加2 236.1 m3·km-2,土壤湿度提高36%～48%,治理效果显著。无论平缓台地集水区或坡地集水区其影响治理效果的主要因素均为保留农田宽度,保留20 m宽度的农田治理效果最佳;当采用全部还林措施治理时灌木是主要影响因素,乔灌混交林治理效果最佳。     

Whole-tree harvesting with stump removal versus stem-only harvesting in peatlands when water quality,biodiversity conservation and climate change mitigation matter

This article examines alternative forest harvesting regimes when ecosystem services in terms of water quality, biodiversity conservation and climate change mitigation are included in the analysis. The harvesting regimes are whole-tree harvesting with stump removal and conventional stem-only harvesting. The harvesting regimes are evaluated under two alternative climate policy contexts. The first alternative is a carbon neutral bioenergy policy, which assumes the carbon dioxide (CO₂) neutrality of bioenergy and produces substitution benefits, as bioenergy replaces fossil fuels. The second alternative climate policy, a carbon non-neutral bioenergy policy, takes into account the fact that bioenergy causes carbon dioxide emissions, producing substitution costs, and that harvested woody biomass affects the ability of a forest to act as a carbon sink. We extend the traditional Faustmann (1849) rotation model to include nutrient load damage, biodiversity benefits, and climate impacts. The empirical analysis is based on Finnish data from a catchment experiment carried out on drained peatland forests. The empirical results show that under a carbon neutral bioenergy policy, whole-tree harvesting with stump removal produces the highest net social benefits. However, if a carbon non-neutral bioenergy policy is assumed, the net social benefits are greater under stem-only harvesting.     

Private native forest policies in New South Wales,Queensland, Victoria and Tasmania

Private native forests in Australia perform a dual production and conservation role, providing an important source of timber, and complementing formal conservation reserves. A comparison of policies for private native forests in New South Wales, Queensland, Victoria and Tasmania illustrates the scope for timber harvesting, the provision for environmental values, and initiatives for responsible and sustainable forest management. The sustainable management of Australia’s forests requires initiatives by both government and landowners to accommodate changes in community attitudes, new management strategies, integrated catchment management principles and both commercial and non-commercial opportunities for forest use. Of all of the Australian states, New South Wales has the most restrictive laws in terms of forest management and harvesting. Queensland and Victorian legislation have a more commercial focus, while Tasmania has a balance of both environmental and commercial objectives. The duty of care for private native forests is a responsibility that falls to the landholder, and while this should be enforced by legislation, the private provision of community benefits requires both recognition and reward. The presence or absence of incentives potentially determines the effectiveness of forest codes of practice.     

Silicate mineral weathering rate estimates: Are they precise enough to be useful when predicting the recovery of nutrient pools after harvesting?

Are current estimates of silicate minerals weathering rates precise enough to predict whether nutrient pools will recover after forest harvesting? Answering this question seems crucial for sustainable forestry practices on silicate dominated soils. In this paper, we synthesize estimated Ca and K weathering rates (derived using seven different approaches) from a forested area in northern Sweden (the Svartberget-Krycklan catchment) to evaluate the precision of weathering rate estimates. The methods were: mass-balance budgets (catchment and pedon-scale); long-term weathering losses inferred from weathered soil profiles (using zirconium as a conservative tracer); strontium isotopes (⁸⁶Sr/⁸⁵Sr) as proxy for catchment export of geogenic Ca; climate based regressions; a steady-state, process-based weathering model (PROFILE) and a dynamic, conceptual catchment geochemistry model (MAGIC). The different methods predict average weathering rates of 0.67 ± 0.71 g Ca m⁻² year⁻¹ (mean ± stdev) and 0.39 ± 0.38 g K m⁻² year⁻¹, suggesting a cumulative weathering release during a forest rotation period of 100 years that is the same magnitude as losses induced by forest harvesting at the end of the period. Clearly, forestry practices have the capacity to significantly alter the long-term nutrient status of the soil and cation concentrations in soil-water runoff. However, the precision in weathering estimates are lower than that needed to distinguish between effects on nutrient pools by different forest practices (complete-tree harvesting versus conventional stem only harvest). Therefore, we argue that nutrient budgets, where weathering rates play a crucial role, cannot be used as basis for resolving whether different harvesting techniques will allow nutrient pools to recover within one rotation period. Clearly, this hampers the prerequisite for sound decision making regarding forestry practices on silicate mineral dominated soils.     

Simulation of the water and nitrogen balances of forests within a catchment in the northeastern German lowlands

The simulation model FOREST-BGC was used to calculate the regional water and nitrogen balances of coniferous and deciduous forests within the Stöbber catchment area over a period of 4 years. This catchment area is located in the northeastern German lowlands. The forest inventory database of the Landesforstanstalt Eberswalde served as a basis for the estimation of initial values of the forest stands and the soil conditions. The mean annual precipitation rate of the calculation period was 560 mm a^–1, the overall mean annual rate of the calculated interception loss was 178 mm a^–1. Furthermore, a mean annual transpiration rate of 329 mm a^–1 and a mean annual soil water discharge of 77 mm a^–1 were calculated by the model. The simulation of nitrogen leaching resulted in a mean annual rate of 7 kg N ha^–1 a^–1. Some simulation results are compared with measurements, and the database used for the estimation of the model initial values as well as for the model calibration is discussed. Additionally, an evaluation of the model performance was carried out for the purposes of our study. Due to the results of this evaluation, the model algorithms of the nitrogen turnover processes, especially in the soil, seem to be too simple and inappropriate for a realistic calculation of the nitrogen budget of forest ecosystems.     

新西兰森林采伐管理制度与借鉴

森林采伐管理是森林资源管理的核心内容之一。在计划经济条件下制定的中国森林采伐管理制度对于森林资源保护起到了重要作用。但是, 随着市场经济不断完善、集体林权制度改革不断深入, 这种管理制度已经不适应现代林业发展的需要, 亟待完善。分析了新西兰在森林采伐方面实施的分类采伐管理、森林可持续经营计划、森林可持续经营许可证、年度采伐计划等管理措施, 期望能为完善中国森林采伐管理制度提供参考模式和经验借鉴。     

黑龙江省林业采运机械化发展变化及驱动力分析

林业机械化是实现林业现代化的基础,采运机械化是林业机械化的重要组成部分.黑龙江省是我国的重点国有林区和主要木材生产地之一,研究黑龙江省的采运机械化发展对于实现我国林业现代化具有重要意义.以黑龙江省森林工业统计资料为基础,对其采运机械化的发展变化进行分析.采用主成分分析法,在SPSS软件中定量计算,找出采运机械化发展的5个驱动因素,并认为驱动采运机械化发展的直接原因是生产成本等经济因素,而根本原因在于森林资源状况的变化.最后预测,未来几年黑龙江省采运机械化水平不会发生显著变化.     

马来西亚森林采伐管理制度研究

林业在马来西亚一直占据相当重要的位置。文中从法律基础、管理体系、轮伐期的确定、森林经营方案制度、采伐审批许可、采伐管理、木材运输以及奖惩措施等方面对马来西亚的森林采伐管理制度进行了全面分析, 并提出加强我国森林采伐管理的建设性意见。     

Factors Affecting Harvesting Intensity in Small-Scale Private Forests in Slovenia

Among other factors, harvesting intensity in private forests depends on property, resource and forest owner characteristics. The research was conducted in Slovenia, a Central European country with very fragmented and small-scale forest property, a large number of owners and co-owners and a long tradition of sustainable forest management. In the nationwide study, data from the Land and Property Register and forest inventory database were used to build a logistic regression model to identify factors that influence harvesting intensity. The results of the model revealed that growing stock, share of conifers, share of forest area under regeneration, total size of forest property in owner- and co-ownership, parcel size and accessibility of the forest area to forest operations increase harvesting intensity. Slope, number and age of owners and co-owners, and skidding distance negatively influence harvesting intensity. The results can offer useful information for policy and decision makers for formulating policy as well as implementing the most suitable mix of policy instruments.     

私有林采伐管理制度:发达国家经验及对我国的启示

通过对世界上8个发达国家私有林采伐制度的研究,总结其经验,对我国集体林采伐制度改革提出建议。发达国家因地制宜设计私有林采伐制度,有充分的法律依据,地方政府具有更多的私有林管理权,各国用森林可持续经营的理念来指导私有林采伐、对私有林采伐行为侧重政策引导。建议我国要坚持集体林采伐许可证制度,完善林木采伐相关法律,政府制定林业规划,林主制定森林经营方案,实行多种政策调控私有林采伐行为,加强采伐后林地更新管理,积极探索各个地区不同的私有林管理制度。     

森林采伐作业环境保护技术

森林采伐应注重经济效益与生态效益的有机结合已成为共识。本文对采伐作业引起林地土壤的干扰与压实、土壤养分变化、保留木的损伤以及采伐作业后溪流水质的变化、林木更新和生长的影响进行归纳和评述 ,介绍了可减少立地破坏的采伐作业技术和采集机械应用的新进展 ,指出我国开展森林采伐作业环境保护技术的研究对策     

基于减少对环境影响的采伐方式的森林采伐作业规程进展

介绍了国际上基于减少对环境影响的采伐理念的区域级或国家级的森林采伐作业规程,包括:斐济的《森林采伐作业规程》、联合国粮农组织的《标准森林采运方法规范》、亚太林业委员会的《亚太区域森林采伐作业规程》和中国的《森林采伐作业规程》.这些规程以生态优先、以人为本、注重效率为基本原则,目的是通过技术的改进,严格控制森林的过度消耗,减少采伐活动对森林及其环境的负面影响,提高劳动效率和木材的利用率,处理好经济、生态和社会的平衡,促进森林可持续发展.文章最后针对我国森林采伐规程实施中存在的问题,提出了分类制定不同区域的森林采伐作业规程,加强科学研究工作,提供技术支撑和理论依据及建立有效的监测和监督体系的建议.     

Nutrient exports under different harvesting regimes in fast-growing forest plantations in southern Europe

In the humid and temperate areas of southern Europe, forest plantations are dominated by fast-growing species (Eucalyptus globulus, Pinus radiata and Pinus pinaster), which are grown on acidic soils with low reserves of available nutrients. In this study the amounts of nutrients exported from the plantations under different regimes and intensities of harvesting were evaluated and, on the basis of the results obtained, silvicultural management methods aimed at improving the nutritional status of the plantations were proposed. We found high ratios between nutrients exported by harvesting and those available in soil stores, indicating limitation for P, Ca and Mg over the long term, which is consistent with frequently found deficiencies of these nutrients. Current harvesting practices (removal of stem wood and bark) result in high rates of export of P, K, Ca and Mg, especially in eucalypt plantations, because of the high productivity and low nutrient efficiency of this species. Comparison of the amounts of nutrients exported by harvesting, with natural inputs (rainfall and weathering) and outputs (stream water), suggests that intensive exploitation of these plantations may result in negative budgets, especially if whole tree harvesting is carried out. The application of fertilizers containing P, Ca and Mg should be encouraged in all cases to favour the return of nutrients, especially where logging residues are extracted. The cost of harvesting in terms of nutrients can also be reduced by careful selection of the tree species planted and of the tree fractions harvested and by reducing the intensity of harvesting.