森林采伐迹地清理方式对迹地土壤理化性质的影响

采伐剩余物迹地清理是森林作业的重要组成部分之一。本文通过在黑龙江省带岭林业局野外迹地取样和实验室分析 ,对森林采伐剩余物迹地清理方式对迹地土壤的影响进行了初步研究。结果表明 ,迹地清理方式对作业迹地土壤理化特性产生一定程度的影响 ,进而影响森林采伐后的迹地天然更新与苗木生长质量。研究结果还表明 ,火烧和堆积方法对迹地土壤物理特性影响不十分显著 ,但对土壤的化学特性影响十分显著 ,尤其是火烧迹地土壤养分流失程度差异比较显著     

Modelling the effects of forest management intensification on base cation concentrations in soil water and on tree growth in spruce forests in Sweden

The study investigated the effects of forest residue extraction on tree growth and base cations concentrations in soil water under different climatic conditions in Sweden. For this purpose, the dynamic model ForSAFE was used to compare the effects of whole-tree harvesting and stem harvesting on tree biomass and the soil solution over time at 6 different forest sites. The study confirmed the results from experimental sites showing a temporary reduction of base cation concentration in the soil solution for a period of 20–30 years after whole-tree harvesting. The model showed that this was mainly caused by the reduced inputs of organic material after residue extraction and thereby reduced nutrient mineralisation in the soil. The model results also showed that whole-tree harvesting can affect tree growth at nitrogen-poor forest sites, such as the ones in northern Sweden, due to the decrease of nitrogen availability after residue removal. Possible ways of reducing this impact could be to compensate the losses with fertilisation or extract residue without foliage in areas of Sweden with low nitrogen deposition. The study highlighted the need to better understand the medium- and long-term effects of whole-tree harvesting on tree growth, since the results suggested that reduced tree growth after whole-tree harvesting could be only temporary. However, these results do not account for prolonged extraction of forest residues that could progressively deplete nutrient pools and lead to permanent effects on tree growth.

     

森林采伐方式对伐后迹地光照条件及更新质量的影响

本文应用野外观测方法,对森林采伐方式（皆伐、择伐、带状皆伐）对迹地光照条件和作业后天然更新质量进行了局部性研究。结果表明,更新树种不仅与种源有关,而且还与光照条件显著相关,即与森林采伐方式有关。     

The influence of some forest operations on the sustainable management of forest soils-- a review

This review paper describes the nature and scale of changesto forest soils brought about by forestry operations. A relativelynon-technical approach is adopted with the aim of stimulatingdebate within as wide an audience as possible. The paper doesnot aim to be exhaustive but rather a position statement. Areaswhere further study is required are highlighted. The concept of sustainability is explored in relation to forestsoils, and the condition highlighted is that impacts of forestmanagement operations should not, in the long term, exceed thecapacity of soil to recover by natural processes (e.g. erosionlosses should not exceed soil formation rates, nutrient removalsshould not exceed nutrient inputs etc.). Soil erosion, nutrientremoval, compaction, and changes in organic matter content andsoil water status are identified as the most important processesinvolved in the impacts of management. The impacts of some of the more intensive forest managementregimes on soil compaction, nutrient removal and erosion ratesappear to be of similar magnitude to the recovery capacity ofsoils. Where the most intensive forms of forest operation areused on susceptible sites some degree of long-term soil degradationappears to be likely, and it can be regarded as valid to describesuch management practices as unsustainable. However, the scaleof occurrence of such management is probably relatively modest,and decreasing. On less susceptible sites, and where less intensiveforms of management are employed, impacts on soils are low enoughfor management to be regarded as sustainable, and are oftenless than under pre-existing land uses. Compaction caused byheavy harvesting and extraction machinery, nutrient depletionresulting from whole tree harvesting on infertile sites whererotations are short, and erosion following cultivation and harvestingon erodible soils are the greatest causes of concern. Compliancewith recent Forestry Commission guidelines should lead to lowerimpacts than those recorded during recent decades. However,rotation-length audits of the impacts of different forest managementregimes on a range of site types are needed before definitivestatements about the sustainability of management operationscan be made.     

Modern forestry vehicles and their impact on soil physical properties

Mechanized harvesting procedures for typical forest vehicles were analysed to examine soil stresses and displacements occurring in soil profiles and to reveal changes in physical properties of forest soils. All field experiments were carried out under traffic lanes of standard forest vehicles in forest stands of the southern Black Forest. The soil stresses were determined using stress state transducers (SST) and displacement transducer systems (DTS) at depths of 20 and 40 cm. Complete harvesting and trunk-logging processes with a total time span of 9 min were observed. The maximum vertical stresses for all experiments exceeded 200 kPa; some experiments showed maximum vertical stresses up to 500 kPa or more at a depth of 20 cm. To evaluate the impact of soil stresses on soil structure, the internal soil strength was determined by predicting the precompression stress. Comparison of soil stress data with the natural bearing capacity of the natural forest soil proves that sustainable traffic is not possible, irrespective of the vehicle type and the working process. Topsoil and subsoil compaction, an increase in the precompression stresses, deep rutting and vertical as well as horizontal soil displacement associated with shearing effects took place and affected the mechanical strength and the physical properties of forest soils. Considering these results, heavy forest machinery has a severe impact on soil physical properties such as air, heat, water fluxes and rootability. In order to sustain the present undamaged soil condition, a change in harvest logistics and organisation is necessary. This can be achieved with a permanent skid-trail system which has already been designed to implement new guidelines in Baden-Württemberg, Germany (Ministerium für Ernährung und ländlichen Raum, Baden-Württemberg 2003, p 27).     

国外森林采伐技术的现状

近30年来,国外森林采伐技术发生了巨大的变化,已经开始实现全盘机械化。文章阐述了国外森林采伐工艺和设备的发展状况,概括地介绍了自行式采伐机械,并对工业发达国家森林采伐全盘机械化的起因做了初步探讨。最后,作者针对当前我国的情况,提出了不应该机械地照搬外国先进技术的意见。     

Landscape-scale disturbance and boreal forest birds: Can large single-pass harvest approximate fires?

Boreal forest birds have adapted to changes caused by natural disturbances such as fire and this adaptation forms the basis for the Natural Disturbance Paradigm (NDP) underlying recent proposed changes in forest harvesting practices in western Canada. To date, this paradigm has been evaluated primarily at the stand level and within conventional harvesting systems. The potential for improvements in avian conservation at the landscape scale by adopting the NDP approach is largely unknown. We examined the effects of landscape-scale disturbances on forest bird communities by contrasting richness and abundance of birds in (1) 16 single-pass harvest sites with residual forest patches, (2) 29 multi-pass harvest sites with residuals; and (3) 15 salvage-logged post-fire sites with variable harvest intensity. We contrasted bird communities in these treatments with those in unsalvaged post-fire sites of similar age. Post-fire sites were used to provide a metric of the Natural Range of Variation (NRV) to be expected in bird communities. Sites were surveyed for avian community composition and abundance 1–5 years post-disturbance. Redundancy analysis indicated that bird communities differed from the NRV in all of the harvest treatments. However, single-pass harvests provided a somewhat better fit to NRV than did multi-pass harvesting. Avian community similarity was influenced by non-linear responses to area harvested, amount of residual retention, residual composition and pre-disturbance forest composition. An optimization routine created from a General Linear Model, suggests that community similarity to NRV can be maximized by using single-pass harvests over multi-pass harvests, harvesting 66–88% of the timber in the planning unit, and retaining 5–19% of the disturbance area as live residual patches, with 50% of harvests having at least 9% of the area in residuals.     

Harvest impacts on soil carbon storage in temperate forests

Forest soil carbon (C) storage is a significant component of the global C cycle, and is important for sustaining forest productivity. Although forest management may have substantial impacts on soil C storage, experimental data from forest harvesting studies have not been synthesized recently. To quantify the effects of harvesting on soil C, and to identify sources of variation in soil C responses to harvest, we used meta-analysis to test a database of 432 soil C response ratios drawn from temperate forest harvest studies around the world. Harvesting reduced soil C by an average of 8 ± 3% (95% CI), although numerous sources of variation mediated this significant, overall effect. In particular, we found that C concentrations and C pool sizes responded differently to harvesting, and forest floors were more likely to lose C than mineral soils. Harvesting caused forest floor C storage to decline by a remarkably consistent 30 ± 6%, but losses were significantly smaller in coniferous/mixed stands (−20%) than hardwoods (−36%). Mineral soils showed no significant, overall change in C storage due to harvest, and variation among mineral soils was best explained by soil taxonomy. Alfisols and Spodosols exhibited no significant changes, and Inceptisols and Ultisols lost mineral soil C (−13% and −7%, respectively). However, these C losses were neither permanent nor unavoidable. Controls on variation within orders were not consistent, but included species composition, time, and sampling depth. Temporal patterns and soil C budgets suggest that forest floor C losses probably have a lesser impact on total soil C storage on Alfisols, Inceptisols, and Ultisols than on Spodosols, which store proportionately large amounts of C in forest floors with long C recovery times (50–70 years). Mineral soil C losses on Inceptisols and Ultisols indicate that these orders are vulnerable to significant harvest-induced changes in total soil C storage, but alternative residue management and site preparation techniques, and the passage of time, may mitigate or negate these losses. Key findings of this analysis, including the dependence of forest floor and mineral soil C storage changes on species composition and soil taxonomic order, suggest that further primary research may make it possible to create predictive maps of forest harvesting effects on soil C storage.     

Changes in aboveground and belowground properties during secondary natural succession of a cool-temperate forest in Japan

Forest development in temperate regions is considered to be a global carbon sink. Many studies have examined forest development after harvesting or fire from aboveground (e.g., biomass) or belowground (e.g., soil nutrient) perspectives. However, few studies have explored forest development from both perspectives simultaneously in cool-temperate forests in Japan. In this study, we examined changes over 105 years in both aboveground and belowground components during secondary natural succession. The aboveground biomass increased for 50 years and reached a plateau in a 105-year-old stand. The N mineralization rate increased during succession for 50 years, but showed a decline in the 105-year-old stand due to the decrease in the nitrification rate in late succession. The percent nitrification (i.e., relative contribution of nitrification to N mineralization) decreased significantly with increasing forest stand age. The N mineralization rates had significant relationships with N concentrations of the dominant tree foliage and litter fall and with the amount of litter fall N. Meanwhile, other belowground properties (i.e., soil pH, phenol concentration, soil microbial respiration, and litter mass loss) did not show any significant relationship with forest stand age. This may be because the soil at the study sites was heterogeneous and consisted of Cambisols and Andosols, the latter of which originally has high organic matter content, and thus may have buffered the effect of the aboveground development. These results indicate that belowground N dynamics are more closely associated with aboveground development than other belowground properties in these forests.     

Effects of harvest management practices on forest biomass and soil carbon in eucalypt forests in New South Wales,Australia: Simulations with the forest succession model LINKAGES

Understanding long-term changes in forest ecosystem carbon stocks under forest management practices such as timber harvesting is important for assessing the contribution of forests to the global carbon cycle. Harvesting effects are complicated by the amount, type, and condition of residue left on-site, the decomposition rate of this residue, the incorporation of residue into soil organic matter and the rate of new detritus input to the forest floor from regrowing vegetation. In an attempt to address these complexities, the forest succession model LINKAGES was used to assess the production of aboveground biomass, detritus, and soil carbon stocks in native Eucalyptus forests as influenced by five harvest management practices in New South Wales, Australia. The original decomposition sub-routines of LINKAGES were modified by adding components of the Rothamsted (RothC) soil organic matter turnover model. Simulation results using the new model were compared to data from long-term forest inventory plots. Good agreement was observed between simulated and measured above-ground biomass, but mixed results were obtained for basal area. Harvesting operations examined included removing trees for quota sawlogs (QSL, DBH >80 cm), integrated sawlogs (ISL, DBH >20 cm) and whole-tree harvesting in integrated sawlogs (WTH). We also examined the impact of different cutting cycles (20, 50 or 80 years) and intensities (removing 20, 50 or 80 m³). Generally medium and high intensities of shorter cutting cycles in sawlog harvesting systems produced considerably higher soil carbon values compared to no harvesting. On average, soil carbon was 2–9% lower in whole-tree harvest simulations whereas in sawlog harvest simulations soil carbon was 5–17% higher than in no harvesting.     

Assessment of the impact of forest harvesting operations on the physical parameters and microbiological components on a Mediterranean sandy soil in an Italian stone pine stand

Forest harvesting operations may have a significant impact on soil physical properties by reducing its porosity and organic functions. Soil variations, in particular bulk density and total porosity, caused by external perturbations as soil becomes compacted due to machinery passes, can lead to changes in biogeochemical cycles that have consequences on soil ecosystems. This study investigated how the impact of forest operations and the elapsed time from harvest can influence: (1) the physical–chemical characteristics of soil and (2) the nitrogen-fixing and nitrifying microbial communities. The study area is located inside the Regional Park of Migliarino, San Rossore, Massaciuccoli (Pisa, Italy). In the study area, the soil has been classified as recent sands with sandy loam texture and slightly calcareous (USDA Soil Taxonomy classification). Soil samples were collected in patchy cut areas (strip cut) of Pinus pinea stand that was harvested in two steps: half area in 2006 and the rest in 2011. Soil samples were collected also in a control area (not harvested) with similar stand and soil characteristics. Statistical analysis was preceded by a test of normality (Kolmogorov–Smirnov test) and a variance homogeneity test (Levene’s test). Considering the dependence of the variables studied (physical and chemical soil characteristics), a MANOVA test and a post hoc Tukey HSD test were applied to determine statistical difference among the three treatments: harvested 2006, harvested 2011 and not harvested. The results did not indicate significant variations to the parameters of shear and penetration resistance, though soil bulk density and total porosity were significantly altered in the short period since forestry operations occurred. These physical changes induced qualitative (presence/absence and number of species) and quantitative (abundance and spatial evenness of the species) variations in the nitrogen-fixing and nitrifying microbial communities.     

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     

Forest floor temperature and relative humidity following timber harvesting in southern New England,USA

Forest amphibians, especially salamanders, prefer forests with shaded, cool, and moist forest floors. Timber harvesting opens the forest canopy and exposes the forest floor to direct sunlight, which can increase forest floor temperatures and reduce soil moisture. These microclimatic changes can potentially degrade the harvested stand for amphibian habitat or affect other biotic resources or ecological processes at the forest floor and in the understory. The degree of forest floor disturbance is directly related to the intensity of harvesting, however, the duration of this effect is unknown. We conducted a study of forest floor temperature and relative humidity over a 12-year chronosequence (1993–2004) of timber harvests. We compared simultaneous, paired measurements of temperature and relative humidity at three positions (soil, forest floor, air) in harvested and control sites over three seasonal survey sessions. Vegetation composition and structure were measured at each survey location. Ambient weather conditions were recorded at three open-field locations across the study area.     

森林采伐对迹地径流流量的影响

本文利用实验方法,对针阔混交林地实施不同方式森林采伐作业后,迹地和径流量发生的变化进行了样地实验研究。结果表明,皆伐对迹地径流量变化影响程度最大。     

Tree encroachment into savannas alters soil microbiological and chemical properties facilitating forest expansion

Forests have been expanding over typical savanna sites for the past 3000 years in the Neotropics.Such invasion can produce a series of environmental modifications on typical savanna;however,it remains unclear how modifications in soil properties,caused by the encroachment of woody species,facilitate the expansion of forest ecosystems under dystrophic conditions.Here we examined chemical and microbiological changes associated with tree encroachment in oxisols of a Neotropical Savanna at Assis Ecological Station,Southeastern Brazil.We predicted that tree encroachment caused by typical forest species would cause significant changes in the chemical and microbiological properties of savanna soils.Soils were sampled at Assis Ecological Station,from savanna sites differing in tree encroachment(typical,dense and forested savanna) caused by decades of fire exclusion.We analysed vegetation leaf area index and leaf litter volume deposited in the studied plots and chemical(pH,organic matter,P,K,Ca,Mg,Al,NO_3~-,NH_4~+) and microbiological(microbial C biomass and dehydrogenase activity) properties of soils under distinct encroachment conditions.Most soil chemical properties did not change along the tree encroachment gradient;however,total P,soil organic matter,soil microbial C and dehydrogenase activity increased from typical savanna to forested savanna.The changes in soil organic matter and dehydrogenase activity were correlated with the values of leaf area index and litter volume along the encroachment gradient.Our results demonstrate that forest species can increase carbon and phosphorus supplies in tropical savanna soils.     

Improved harvesting systems for wet sites

Environmentally acceptable and economical forest operations are needed for sustainable management of forest resources. Improved methods for harvesting and transporting timber are especially needed for wet sites. As the demand for hardwood lumber continues to increase, improved and alternative methods are needed to ensure acceptance of timber harvesting for the wet site conditions that are typical of bottomland hardwoods. Some alternative technological developments include grapple saw feller-bunchers, wide tires, larger forwarders, clambunk skidders, two-stage hauling, mats, cable systems, helicopters and towed vehicles and air-cushioned vehicles. These developments have the potential to improve the performance of the harvesting system and to reduce the negative effects of conventional operations on conventional sites and on difficult sites such as wet areas. Although many of these new alternatives are now operational, others are just concepts or evolving prototypes. More research is still needed to optimize these alternative technologies and to reduce costs associated with their implementation.     

Changes of key soil parameters five years after forest harvesting suggest slow regeneration of disturbed soil

Forest soil is susceptible to changes in its top layers. These changes occur during ground-based forest harvesting and the rate of soil regeneration depends on the environmental conditions and the extent of the disturbance. This paper was focused on analyzing the changes of soil characteristics such as the depth of the erosion profile, bulk density of soil, its penetration resistance, and the subsurface concentration of CO₂ in soils five years after forest harvesting. The study took place in four forest stands harvested by a skidder and a harvester/forwarder combination. Statistical analyses did not prove significant changes of the characteristics of the disturbed soil after the five-year period without machine traffic: the profile depth did not change significantly, except for one stand, where the ruts became deeper. Other characteristics, such as the bulk density of soil also did not show any significant regeneration (1.29–1.36 g cm^?3 in the rut; initial measurements versus 1.34–1.38 g cm^?3 in the rut; repeated measurements). The penetration resistance, as well as the subsurface CO₂ concentration, were variable, and the results inconclusive. Our results suggest that five years was not enough time for soil to regenerate significantly after being disturbed by ground-based machinery.     

林区不同土地利用模式对土壤理化性质与酶学特性的影响

土壤在调节地球气候和物质循环方面起着重要作用,但是由于人为因素的影响,不当的土地经营模式（如居民用地、农业耕地、毁林开荒）对土壤质量产生了深刻影响,使土壤质量发生变化。本研究对黑龙江省尚志市帽儿山林场的4种不同的土地利用与经营模式（森林土壤、农田土壤、场部用地和森林迹地）下的土壤理化性质和土壤酶活性进行测定与分析,探讨不同土地利用模式对其土壤理化与土壤酶学特性的影响。研究发现4种土壤类型的10个采样点的10个土壤理化指标和5个土壤酶活性指标间存在显著差异,土壤质量从高到低依次为：森林土壤,森林迹地,林场场部用地,农田用地。相关分析表明土壤脲酶和过氧化氢酶与土壤含水量、土壤全氮、土壤全碳、土壤有机碳、可溶性全碳和可溶性有机碳含量之间成显著正相关;多酚氧化酶与土壤pH成显著正相关。因此,不同土地利用方式对土壤理化性质和土壤酶活性产生显著影响。     

The effect of logging on vegetation composition in Western Massachusetts

Forest harvesting is one of the most significant disturbances affecting forest plant composition and structure in eastern North American forests, yet few studies have quantified the landscape-scale effects of widespread, low-intensity harvests by non-industrial private forest owners. Using spatially explicit data on all harvests over the last 20 years, we sampled the vegetation at 126 sites throughout central and western Massachusetts, one-third of which had not been harvested, and two-thirds of which had been harvested once since 1984. Seedling and sapling densities increased with increasing harvest intensity, but decreased to levels similar to unharvested sites by year 20 for all but the most intensive harvests. The composition of understory trees appears to be only slightly changed by harvesting, and was strongly correlated with adult tree composition. Regeneration was dominated by Betula lenta followed by Pinus strobus; Quercus spp. exhibited little sapling recruitment, even in Quercus-dominated stands. Total vascular plant species richness increased substantially with harvesting on low C:N sites (i.e., rich soils), but was only slightly increased on high C:N sites. While harvesting was associated with a statistically significant change in vascular plant composition, non-metric multidimensional scaling revealed that climate (temperature, precipitation) and C:N ratios were the major correlates of composition. Overall, the compositional impacts of harvesting were minor, perhaps because of the low-intensity of harvesting. However, our results support observations from elsewhere in the northeastern U.S. of limited oak regeneration on both harvested and unharvested sites. In addition, our results suggest that increased harvest intensity may be expected to alter forest composition, particularly on rich sites where invasive species may increase as a result of harvesting.