Assessing the effects of site factors on the productivity of a feller buncher:a time and motion analysis

We evaluated,for the first time in Turkey,the productivity of a feller buncher during clear-cut operations of two Brutian pine stands located in Canakkale,northwestern Turkey with different diameter classes and terrain conditions.In the first stand with 24.6 cm average DBH,the feller buncher cut full trees and moved them to roadside.In the second stand with 34.3 cm average DBH,the feller buncher cut trees in two stages due to their larger diameters and the relatively steep and rough terrain conditions of the site.The effects of specific stand features,DBH and tree height measurements were assessed through statistical analysis in relation to productivity.The results indicate that the average productivity for the first stand was about 118 m^3h^-1,while it was about 80 m3h-1 in the second stand.Even though tree diameter and volume were higher in the second stand,productivity decreased by32.3%due to extra time spent on the two-stage cutting operation.The results revealed that harvesting operations should be planned carefully and the right equipment selected by accounting for different tree sizes,terrain conditions and machine specifications in order to better understand their effects on production.     

我国森林资源采伐消耗特点分析

通过第八次森林资源清查成果分类汇总,分析我国森林资源采伐消耗的现状、结构及区域分布特点,以历次森林资源清查结果分析我国森林资源采伐消耗动态变化趋势及特点,提出了加强林木采伐管理、科学经营森林、提高木材供给能力的对策、措施和建议。     

Oil yield and quality variation between sexes in Osyris lanceolata (African sandalwood) and its value as a fodder plant in Tanzania

African sandalwood (Osyris lanceolata) is widely harvested in East Africa for extraction of oil, which is used in the fragrance and perfumery industry. Over the years, harvesting of the species has been concentrated to female plants because it is claimed that they yield more and better quality oil compared to males. However, data to support these claims is lacking. Osyris lanceolata is also used extensively by pastoralists as feed supplement during the dry season, yet little information on the species’ nutritive value exists. Oil yield and quality variations between male and female O. lanceolata and its nutritive values were evaluated to ascertain the purported reasons for sex selectivity in harvesting, and to determine the potential value of the species as a fodder plant. Oil yield was determined by extracting oil from a known amount of wood, while quality assessment was done by determining the amount of santalol, a prime determinant of sandalwood oil quality. The species’ potential as a fodder plant was determined by analyzing the nutritive value and digestibility of leaves and fruits. There was no significant variation (p = 0.856) in oil yield between sexes, though populations differed significantly (P < 0.001). The highest oil yield was 9.32 ± 0.611%. Likewise, sexes did not differ significantly (P = 0.655) in oil quality, though populations differed significantly (P < 0.001). The highest santalol content was 11.1%. It is concluded that sex selectivity during harvesting has no relation to oil yield and quality. However, population selectivity is strongly justified due to the huge variation in oil yield and quality, and is likely to be the major reason for over-exploiting some populations. It is recommended that there is a need to refrain from overharvesting of females within populations, since the practice is likely to erode the genetic vigour of the species and affect its sustainability. Nutritive studies revealed the species to have 15.9–19.7% crude protein, 15.9–24.0% crude fibre, 0.77–0.81% fat/oil, 97.5–97.8% dry matter, 8.5–10.3% ash content, 72.2–72.4% digestibility. These figures are within the acceptable range, suggesting that both leaves and fruits of the species are a potential alternative source of animal protein where protein supplements are not available or expensive.     

Whole tree harvesting can reduce second rotation forest productivity

The practice of harvesting forest residues is rapidly increasing due to rising demand for renewable energy. However, major concerns have been raised about the sustainability of this practice and its net impact on productivity, in particular through negative effects on the growth of subsequent tree crops. We measured height, diameter at breast height (DBH) and tree spacing density on 23-year-old second rotation stands of Sitka spruce (Picea sitchensis), following whole tree harvesting (WTH—of all above ground biomass, by cable crane) or conventional stem-only harvesting (CH) of the first rotation crop. Overall, WTH reduced tree DBH by 10.3% (p = 0.017), with weaker evidence that it may have reduced height (by 8.2%, p = 0.164) and stand basal area (by 15.3%, p = 0.101). However, treatment effects differed greatly between individual blocks and, analysed separately by block, significant differences (WTH plot trees smaller than CH plot trees) were most notable in the two more exposed south-facing blocks (where, in both cases, p < 0.01 for height and p < 0.05 for basal area). Variation in productivity between the experimental plots cannot simply be attributed to preharvesting site environment – no correlation was found between first rotation and second rotation productivity – nor was treatment effect explained by differences in tree spacing density. Treatment effects can be attributed to the removal of three to four times larger quantities of N, P and K in the tree biomass by WTH than by CH of the first rotation crop, combined with greater competition with tree natural regeneration and other vegetation in WTH plots during the early stages of the second rotation. Soil moisture was higher in WTH plots but there was no evidence that WTH increased soil acidity or aluminium mobility nor that it decreased soil organic matter. The results also highlight the complexities of predicting the effect of harvesting treatment on future productivity, even within single-age, single-species forests. The study demonstrates the risk that WTH can reduce second rotation productivity of conifer forests in acidic upland sites, and that this practice will only be sustainable with appropriate interventions to overcome shortage of nutrients and high levels of vegetation competition.     

A geospatial and temporal framework for modeling gaseous N and other N losses from forest soils and basins,with application to the Turkey Lakes Watershed Project,in Ontario,Canada

This article quantifies pre- to post-harvest gaseous N emissions and other N losses from forest soils and basins geospatially and temporally via digital elevation and hydrological modeling, using daily rain, snow and air temperature records, annual atmospheric N deposition rates, and basin-specific soil and forest specifications as input. The approach relates gaseous N losses from soils to soil temperature and water-filled pore space (WFPS) as affected by the depth-to-water (DTW) below the soil surface. The approach is applied to the Turkey Lakes Watershed Project (TLW) in Ontario, 60 km north of Sault St. Marie, where basin-wide N losses due to denitrification would mostly be restricted to the wetland portions of the basin. Basin-wide N losses via denitrification and stream export (mineral N and dissolved organic N) were empirically related to upland N mineralization and soil leaching as controlling processes. The calibrated model calculations, set to conform to the field-monitored N concentrations in TLW streams, suggest that the harvest-induced nitrification and denitrification pulses would be strongest near the end of the first post-harvest year, dropping to background levels within about 4–5 years later. The article concludes with assessing basin-specific denitrification efficiencies in relation to atmospheric N deposition and basin-to-basin wetland coverage.     

林改后永安市森林采伐管理制度的探索

集体林权制度改革后,为探索完善森林资源采伐限额管理新机制,永安市开展商品林按面积控制采伐试点。通过对改革试点中存在问题的研究与分析,提出了进一步完善森林采伐管理制度的对策和建议。     

松材线虫病疫木不同伐除方式对森林植物群落演替的影响

采用标准地调查法,对不同立地条件下松材线虫病除治迹地生态系统的植物种类丰富度、密度、多样性指数、均匀度指数及垂直结构情况进行调查和分析。结果表明:立地条件的差异和疫木不同采伐方式对植物群落次生演替的进程和方向都有不同程度的影响。立地条件较好,无论是皆伐、择伐还是不采伐,除治迹地植物群落乔木层和灌木层较受害前纯林的种类丰富度和多样性指数都有一定程度的增加;而立地条件较差的,经皆伐后,植物群落的种类丰富度和多样性指数不仅没有增加,反而降至极低,原有松林群落向灌丛方向退化。     

现代电子称重技术发展对森林收获计测的影响

回顾森林收获计测技术的发展历史,分析现代电子称量技术的发展应用前景,指出木材及木制品以体积计量计价的局限性和以重量计量计价的优势,认为当前一些木材市场上出现的买卖双方以重量而不是以材积计量计价现象有其历史必然性。基于以重量计量计价更为客观、准确、快捷、高效,并大幅降低成本的优势,其在纸浆等工业原料林经营、林业碳汇贸易等方面具有广泛应用潜力。     

Toward sustainable harvesting of Africa's largest medicinal plant export (Prunus africana): a case study in Tanzania

Global demand for treating prostate disorders with Prunus africana bark extract has made P. africana Africa's largest medicinal plant export. Unsustainable harvesting practices can lead to local extirpations of this multipurpose tree. Survey research targeting P. africana harvesters in a Tanzania forest reserve revealed that 78% of them used unsustainable harvesting practices. This research focused on establishing a socioeconomic profile of the harvesters, the profitability of their business operations, and identifying the factors that influence their selection of harvesting practices. Results indicate that harvesters have above-national-average education, double the average family size, and generate income exceeding government's minimum wages. Large family size and high earning potential imply increased future harvesting activity. Logistic regression results indicate that education and training level could predict the likelihood that a harvester would use unsustainable harvesting practices. Local- and district-level government organisations could implement a resource assessment as a basis to design and implement harvesting schedules and ensure that the harvesters receive appropriate training, regardless of their education level.     

黄土高原适于造林的雨水收集系统设计方法

根据黄土高原地区降水缺乏的自然条件 ,该文提出了 30 0mm到 6 0 0mm地区用于造林的集水设计与施工方法 .这种集水系统由不同形式、大小的种植区与产流区组成的微型集水区形成 ,其设计依据主要是降雨、产流区的径流系数、来自树木和土壤的蒸散、土壤水分亏缺及降水资源环境容量等等 .经过YJG(有机硅化学处理 )处理的产流区、拍光压实产流区和自然坡面的径流系数分别为 0 8 0 89,0 2 3 0 36 ,0 0 8 0 10 根据彭曼法计算的土壤水分亏缺量在 5 0mm到 30 0mm之间 .在降雨量为 4 0 0mm的地区经过YJG处理之后用材林每株林木的产流面积为 3 4m2 ,经济树种为 8 10m2 ;经过压光拍实处理之后用材林每株林木的产流面积为 6 8m2 ,经济树种为 10 12m2 ;自然坡面对于用材林每株林木的产流区面积为 8 10m2 ,经济树种为 12 15m2 采用这种系统经过YJG处理产流区、拍光压实产流区和保持自然坡面的微型集水区中树木的蒸腾量分别是总集水量的 4 7 6 5 % 5 3 31% ,2 4 10 % 36 93%和 18 6 5 % 2 9 5 5 % .这种大面积应用于黄土高原地区的系统被称为径流林业 .