Acidity in four coniferous forest soils after different harvesting regimes of logging slash

The soil acidity of four coniferous sites, two in S Sweden and two in N Sweden, were studied 7–9 years after clear‐felling. Each site had three different slash treatments; (a) all slash harvested, (b) only needles remaining, and (c) all slash remaining. Our results verify that harvesting of slash after clear‐cutting means an acidification of the organic horizon in acid forest soils. On plots subjected to full slash harvest the pH‐value of the forest floor was 0.2–0.4 units lower than that of slash‐covered ones, and at three of the four study sites the exchangeable acidity was significantly higher on the slash‐cleared plots. Plots with only needles remaining were generally intermediate in acidity. The change in exchangeable acidity corresponded to approximately 10% of the theoretically estimated proton load caused by slash harvesting. The rate of proton flux associated with whole‐tree harvesting varied between 7–65 meq m^‐3 yr^‐1, which roughly corresponds to the amounts deposited in precipitation. Harvesting of stems accounted for about one third and needles for one third of the proton load.     

森林采伐与森林生态关系的研究

森林采伐与森林生态的关系是辩证统一、相互制约的。如何以森林生态理论为基础.因林因地、科学的选择采伐方式、采伐强度,使森林始终处于动平衡状态。达到采伐促进森林天然更新和增长;更新是为了将来的森林采伐。充分发挥森林的经济效益、生态效益和社会效益,实现森林的可持续发展。     

Characteristic site disturbance due to harvesting and extraction machinery traffic on sensitive forest sites with peat soils

The effects of wood harvesting and extraction machinery traffic on sensitive forest sites with peat soils were characterised with the objective of quantifying the threshold levels beyond which significant site impacts (compaction and rutting) would occur. The treatments involved running the machines in selected extraction racks (i.e., 3 m wide machine routes) while conducting normal wood thinning and extraction operations comprising one and two passes by the harvester and the forwarder with full payload, respectively. Soil disturbance thresholds were established by testing the level of significance of the difference in induced soil damage and compaction before and after machine traffic treatments. For volumetric soil water content lying between 10.0 and 14.9%, threshold cone penetration resistance levels for two 600/55–30.5 tyres were found to range from 594 to 640 kPa for deep-raised peat soil with initial strength lying between 524 and 581 kPa. In general, the proportion of the total rut depth data in each rack that exceeded the threshold level of 21.5 cm was about 5%. The threshold value corresponds to sinkage equivalent to 15% of the overall wheel diameter of the harvester, above which machine mobility would be hampered considerably. In addition, after harvester traffic the mean rut depth per unit rack length was 10.2×10⁻² cm/m, and it ranged from 0.7 to 24.7×10⁻² cm/m.     

Impact of forest harvesting on river runoff in the Xiaoxing’an Mountains of China

Using the runoff experiment method in a large basin combined with the contrast experiment in a small watershed, and based on the runoff and forest resources data for the past 35 years, this paper studied the serial changes of river runoff in the Xiaoxing’an Mountains after forest harvesting. The results showed that the river flow increased in the initial ten years after forest harvesting, but decreased gradually with the growth and crown closure of the Larix gmelini plantations. The river flow tended to be the same or even lower than the level before harvesting. The river runoff had a close correlation with annual rainfall, the size of forest harvesting and regeneration. A significant positive correlation was observed between the annual flow and the size of forest harvesting, which resulted in the increase of river runoff after forest harvesting. Forest harvesting could also significantly increase the peak flood and snowmelt runoff. There was a negative correlation between the regenerated forest area and annual flow, and thus, forest regeneration would decrease annual flow. __________ Translated from Chinese Journal of Applied Ecology, 2005, 16(12): 2,259–2,262 [译自: 应用生态学报]     

论森林采伐与“天保”工程的统一性

保证森林采伐与天保工程有机的统一.首先要提高采伐与天保工程统一性的认识;然后要合理采伐.大力培育速生护林;其次要处理好当前与长远的关系。     

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.     

Soil moisture content as a predictor of soil disturbance caused by wheeled forest harvesting machines on soils of the Western Carpathians

Limiting surface soil disturbance caused by forest harvesting machines is an important task and is influenced by the selection of efficient and reliable predictors of such disturbance. Our objective was to determine whether soil moisture content affects soil load bearing capacity and the formation of ruts. Measurements were conducted in six forest stands where various machines operated. We measured the formation of ruts along skid trails in connection with varying soil moisture content. Soil moisture content was determined through the gravimetric sampling method. Our results showed that severe(rut depth16–25 cm) to very severe disturbance(rut depth [26 cm)occurred in forest stands where the instantaneous soil moisture exceeded its plasticity limits defined through Atterberg limits. Atterberg limits of soil plasticity ranged from 26 to 32 % in individual stands. Regression and correlation analysis confirmed a moderately strong relationship(R = 0.52; p \ 0.05) between soil moisture content and average rut depth. This confirmed that soil moisture is a suitable and effective predictor of soil disturbance.     

Short-term impacts of harvesting and burning disturbances on physical and chemical characteristics of forest soils in western Newfoundland,Canada

The short-term impacts of prescribed burning were determined for the physical and chemical properties of a forest soil on a clear-cut in western Newfoundland, Canada. The experimental site was predominantly covered by black spruce trees (Picea mariana Mill.) that were harvested in 1996. In August 1998, prescribed burning removed most of the logging residues left on the site after harvesting, all above-ground surface vegetation, and parts of the upper humus layer. In October 1998, field samples were taken from four replicated burned plots and four replicated unburned plots. In each study plot, soil samples were taken from the organic layer (F+H) and from the top 10 cm of the mineral soil. In the burned treatments, mass of the humus layer (F+H) was reduced by 24% and, because of the accretion of basic ash materials, acidity of the humus layer was also reduced by up to 1 unit. In the organic layer and the mineral soil, total contents of Mg, Ca, and P, extractable Mg and Ca, available P, sum of NH₄Cl-extractable cations, and C/N ratios were increased by burning, while total C and N as well as total and extractable K remained unaffected by burning.     

Nutritional potential of fodder trees on clay and sandy soils

In this paper we focus on the functional role of trees for livestock as fodder in silvopastoral systems, available for (dairy) cows within or around pastures. Farmers often report that cows browse from trees, however, little is known about the nutritional value of different tree species. Therefore, the objective of this study was to assess the effect of soil type and season on the nutritional potential of leaves from Fraxinus excelsior, Alnus glutinosa and Salix viminalis. Leaf samples were collected at 10 sites in the Netherlands on clay and on sandy soils in June, July and September and were analysed for digestibility, crude protein, macro and micro element concentrations. We conclude that the nutritional value of tree leaves differs between the studied tree species. Regarding the seasonal variation, we found a main effect of sampling period on the crude protein, calcium, phosphorus, copper and selenium concentration of leaves. No main effect of soil type was found on the nutritional value of leaves. Significant interactions were found for species × sampling period (digestibility, calcium, sulphur) and species × soil (digestibility, calcium). For the zinc and selenium concentration in tree leaves, a significant species × soil × sampling period interaction was found. We conclude that trees can play a role for supplying protein, and macro and micro elements to livestock, but that it depends on which tree species is used.     

浅析森林作业对林地土壤的影响

本从土壤压实、水土流失及沙漠化等5个方面简要论述了森林作业对林地土壤的不利影响。 指出采取适当的森林作业方式和合理的森林作业技术是减轻其对林地不利影响的必要手段。     

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。     

Effects of experimental forest harvesting on oribatid mite biodiversity

Ecosystem-based management (e.g. partial cut harvesting) attempts to mimic natural forest dynamics and maintain structural complexity, and this less intense harvesting may minimize the impact on forest floor fauna and help maintain soil system biodiversity. We tested how different experimental harvesting regimes affect the diversity, abundance and composition of Oribatida at the sylviculture et aménagement forestiers écosystémique (SAFE) research forest located in the Abitibi region in NW Québec. Litter and soil were sampled in June 2006 in the mixedwood boreal forest at SAFE where the following treatments were applied and replicated three times: clear cut harvest, 1/3 partial cut harvest, 2/3 partial cut harvest, prescribed burn (after clear cut harvest) and uncut control. Eight years after harvest, partial cuts had more similar species composition to the uncut control within their respective blocks; however, burned habitat showed a shift in species dominance patterns and harboured a relatively distinct composition and species richness compared to treatments. With the exception of samples from clear cuts, species composition of the harvesting treatments was more similar within blocks than among blocks, suggesting that for less intense harvesting practices, spatial scale (i.e. regional factors) could have a greater influence in structuring oribatid assemblages than harvesting regime, but in more severe disturbances such as burn-after-clear cut harvest, habitat is altered enough to affect oribatid biodiversity.     

Impact of wildfire intensity and logging on fungal and nitrogen-cycling bacterial communities in British Columbia forest soils

Wildfire and logging are common disturbances in the forests of northwestern North America, causing changes in soil chemistry and microbiology, including fungal and nitrogen-cycling bacterial communities. These organisms play key roles in nutrient cycling, and affect the regeneration of tree seedlings after disturbance. We studied the effects of wildfire and logging on fungal and nitrogen-cycling communities in the rhizosphere of 16 month-old Douglas-fir seedlings as they regenerated in burned and logged soils. Seeds were planted against root windows that were set up vertically in the soil, with a removable front panel used to access the seedling rhizosphere soil surface. Windows were established in control, lightly burned, and severely burned plots, as well as two types of logged plots (clearcut and screefed clearcut). Soil scrapings from the root window–soil interface were taken and the structure of fungal and nitrogen-cycling communities was resolved using length-heterogeneity PCR (LH-PCR) of fungal nuclear ribosomal RNA genes, and terminal restriction fragment length polymorphism (T-RFLP) analysis of nifH and nosZ genes. We found striking differences in the community structure of fungal, denitrifying, and N-fixing communities in response to burning and logging. With the exception of clearcut and screefed clearcut, which were generally similar, each treatment had a unique impact on community structure for these genes. Burning and logging also impacted the relative richness and evenness of these communities. Fungal relative richness and evenness increased in response to logging and severe burning, while denitrifier relative richness and evenness increased in all disturbance treatments, and N-fixing bacterial relative richness and evenness decreased in response to burning. The greatest differences in microbial community structure, relative richness, and evenness were found in the comparisons of lightly burned and logged treatments. The results suggest that the presence of an intact forest floor influences soil microbial communities less than the presence of living trees.     

森林采运作业环境成本核算的研究

本文总结了森林环境服务价值评价的方法 ,在分析了森林有形产品的经济价值和无形产品的环境服务价值的基础上 ,建立了采运作业环境成本核算的数学模型。     

Soil compaction due to heavy forest traffic: measurements and simulations using an analytical soil compaction model

? Context

Models for predictions of soil compaction following forest traffic represent important decision tools for forest managers in order to choose the best management practices for preserving soil physical quality. In agricultural soil compaction research, analytical models are widely used for this purpose.

? Aims

Our objective was to assess the ability of an analytical model to predict forest soil compaction under forwarder traffic.

? Methods

We used the results from two experimental sites set up in north-eastern France in 2007 and 2008 to compare simulations using the SoilFlex model with observed bulk density following forwarder traffic.

? Results

The best model-based predictions were found when considering the mean initial soil conditions and an increased rebound parameter in the upper soil layers (0–10 cm) in comparison to the deeper layers (10–50 cm). The need to increase the rebound parameter in the soil surface layer to improve model accuracy was attributed to a large soil organic matter content in the uppermost layers of forest soils. For the site where initial soil mechanical parameters were measured as a function of soil bulk density and water content, the model performance was good, with a root mean square error (RMSE) of 0.06. The model performed poorer (RMSE of 0.11), especially for the surface soil layer, for the second site that was wetter at the time of traffic and where soil mechanical properties were not measured but estimated by means of pedo-transfer functions.

? Conclusions

SoilFlex was found to yield satisfactory predictions and could help forest managers estimate the risk of compaction and to select the most appropriate machinery for given soil conditions in order to preserve the soil from physical degradation during traffic in forest ecosystems. However, our results emphasise the need for research on soil mechanical properties of forest soils, in particular on the role of soil organic matter and roots on soil compressive properties.     

Short-term effects of group-selection harvesting on breeding birds in a northern hardwood forest

We used a before-after, control-impact design (one year pre-harvest, two years post-harvest) and unlimited-radius point counts to study the effects of typical group-selection harvesting (0.5 gaps ha⁻¹ placed near seed trees within a standard single-tree selection harvest) and intensive group-selection harvesting (4 gaps ha⁻¹ placed on a grid with no harvesting between gaps) on the composition and abundance of breeding birds in tolerant hardwood forests in Algonquin Provincial Park, Ontario. Percent similarity between pre- and post-harvest bird communities was 5–9% lower in selection harvested stands than in reference stands. Differences in percent similarity among the three treatments were not significant, however, suggesting that the changes in the bird community in stands harvested with group selection were not substantially different than those in reference stands. Abundance of aerial foragers and tree-and-shrub nesters increased in response to typical and intensive group selection in the second year post-harvest. By contrast, bark foragers and cavity-nesters decreased in the first year post-harvest and then increased in the second year post-harvest in response to typical group selection. Abundance of 16 (73%) of 22 species was not affected by harvesting. Blue Jay (Cyanocitta cristata), Chestnut-sided Warbler (Dendroica pensylvanica), Least Flycatcher (Empidonax minimus), and White-throated Sparrow (Zonotrichia albicollis) increased in response to intensive group selection in the first or second year post-harvest, whereas Chestnut-sided Warbler, Hairy Woodpecker (Picoides villosus), and White-throated Sparrow increased in response to typical group selection in the first or second year post-harvest. Ovenbird (Seiurus aurocapilla) decreased slightly in response to typical group selection in the second year post-harvest. Our short-term data suggest that intensive, rather than typical, group-selection harvesting is preferred for maintaining densities of cavity-nesting birds and Ovenbird; whether these advantages continue through the remainder of the cutting cycle and beyond requires further investigation.     

草沙地阔叶树混交林造林试验

为提高草沙地系统稳定性,采用阔叶树混交方式营建草沙地防护林。树种配置以乡土、牧用树种为主,体现了树种的多样性。阔叶树易萌发、生长快,落叶可以被牲畜直接利用,增加了草地牧业利用的产量。沙地草地阔叶树混交林的营建,发挥了以林保草、以林促牧的作用,有利于建立林草复合经营模式。     

The effects of teak monoculture on forest soils: a case study in Bangladesh

Teak plantations date back to 1871 in Bangladesh.This study was designed to assess how teak monoculture has impacted the soil properties in Bangladesh.Multiple linear regression and correlation matrices were estimated to evaluate these impacts.The means of soil physicochemical properties were compared across various attributes of the plantations.Older plantations accumulated more organic carbon in the soils than the younger plantations.Excessive removal of litter from the forest floor resulted in reduced levels of N, P, K, and other nutrients in the soils.Since bulk density was continuously decreasing deeper into the soil, the penetration of mineral nutrients into the soil was low.Furthermore, moisture content in the topsoil was significantly lower than that in the bottom layers due to the exposed and dry condition of the forest floor under teak plantations.For improving depleted teak plantation soils, teak could be planted with other tree species rather than just in monocultures.In addition, the forest floor could be enriched with leguminous herbs and shrubs to improve soil health in these plantations.