A study on the productivity and cost of cable logging in Turkey

Tower yarders have recently been introduced to forestry in Turkey. Clarification of the productivity and cost of logging using the tower yarder is often requested because the cost for machinery is a significant factor in all calculations concerning mechanized operations. Machines are often extremely expensive compared with the low cost of labor in developing regions. In this study, a new logging system using a tower yarder was compared with a conventional system using a stationary yarder in terms of productivity and cost. The research was conducted in the northeast of Turkey, in 1989 and 1992. The productivity of the tower yarder and the stationary yarder was found to be 5.655 m³/h and 5.002 m³/h, respectively. Harvesting cost was analyzed based on observed productivity. The harvesting costs of the tower yarder and the stationary yarder were found to be 47,410 TL/m³ and 17,553 TL/m³, respectively. With the tower yarder, the machine cost reached 93.1 % of the harvesting cost while the machine cost using the stationary yarder reached 71.1%. A part of this paper was orally presented at the 3rd Annual Meeting of the Japan Forest Engineering Society (1996).     

Importance of soil extractable phosphorus distribution for mature Norway spruce nutrition and productivity

Phosphorus is an essential nutrient for forest growth. In this study, we assessed the impact of soil extractable phosphorus using two simple extraction methods on nutrition and productivity of Norway spruce in sixteen mature forest stands on different bedrocks and soils in Bavaria, Southern Germany. Representative trees were sampled for needles, twigs, branches, stem bark, and stem wood. Total phosphorus content in the tree parts and soil phosphorus stock extractable with citric acid and sodium bicarbonate up to a soil depth of 80 cm were determined. We found that easily soil extractable phosphorus is a suitable indicator for estimating phosphorus uptake and stand productivity in Norway spruce. In contrast, organic layer phosphorus showed no significant correlation with aboveground biomass phosphorus contents. In the biomass, the highest phosphorus contents were measured in young needles and twigs, but the highest correlation with soil phosphorus was detected for phosphorus contents in needles and bark. The stock of phosphorus extracted by citric acid down to 40 cm soil depth revealed the best correlation with phosphorus in needles and bark. Therefore, as a supplemental or alternative method to needle analysis, our study suggests the use of phosphorus contents in stem bark to evaluate tree phosphorus nutrition. These results highlight the suitability of the citric acid soil extraction method to characterize plant available phosphorus in Norway spruce ecosystems.     

Excavator-based processor operator productivity and cost analysis in Zululand,South Africa

Operator impact on productivity and cost using similar processor machines was addressed in this case study. The study had two objectives: (1) determine the extent of operator productivity variation between six processor operators in a harvesting operation; and (2) determine potential cost implications associated with operator productivity variation. The study was carried out on the Zululand coastal plains near Kwambonambi. A multistem mechanised harvesting system, working in Eucalyptus grandis × camaldulensis pulpwood stands (with an average rotation length of seven years) was observed. The operators had all been operating their respective processors for 18 months; i.e. since the inception of the harvesting operation and had received similar in-house training. Time studies were carried out on the processors’ cycle times, and note taken of the respective operators working the machines during the time studies. Cycle time for each machine was measured as the time between a delimbed and debarked tree length leaving the processor head and the following tree length leaving the head. The required number of observations per processor was determined by cycle time and work element time variation. It was found that operators varied by up to 58% in terms of productivity, 24% in terms of utilisation and 70% in terms of cost. The potential difference in cost between using the cheapest operator and the most expensive operator was R9.34 m^?3, R4 438 d^?1 and R1 384 752 y^?1.     

Time consumption, productivity, and cost analysis of skidding in the Hyrcanian forest in Iran

The performance of the skidder Timber jack 450 C was presented in timber skidding of non-coniferous trees in hilly and mountainous conditions.An empirical time study was conducted to evaluate the current skidding system in Hyrcanian forest in northern Iran for improving production rate of skidding and finding out the production cost for planning.Based on the identified elements of skidding work phase and 130 recorded cycles,we calculated the models for effective time consumption,total productivity,and unit cost.The validity of the model was tested at 95% confidence interval.The average load volume per cycle was 2.82 m 3,average one way skidding distance was 450 m,and the average slope was 18%.The average travel speed of unloaded skidder was 5.8 km·h-1,and the average speed of loaded skidder was 0.1 km·h-1 higher than the speed of the unloaded ones.The travel speed was predominantly affected by longitudinal slopes and types of strip roads.The average speed of pulling the cable was 1.16 km·h-1,and that of load winching was 0.74 km·h-1.The average outputs in skidding was 10.6 m 3 ·h-1 and the unit cost was 12.1 US$ per hour.The time consumption and productivity of skidding depends on distances and slope,number of logs per cycle,volume,log length,etc.However,the influence of variables is not the same.     

Effects of tax incentives on long-run capital formation and total factor productivity growth in the Canadian sawmilling industry

The goal of this study was to analyze effects of tax incentives on long-run dynamics of total factor productivity (TFP) growth and capital formation in the Canadian sawmilling industry over a 40-year period (1961–2000). Simulated tax incentives involved increasing capital cost allowance and investment tax credit and reducing corporate income tax. The production technology was specified as a function of capital, labor, energy, sawlogs, and a time dependent technological progress variable. A translog multilateral index number model was applied to measure and analyze TFP.Two analytical phases were followed. In the first phase, without the tax incentives, we analyzed annual levels and growth rates of TFP1; and parametrically examined effects of output growth and time dependent technology on the growth of TFP1. Over the study period, the average annual growth rate of TFP1 was 2%; and the parametric results revealed that the marginal effects of each of output growth and technological progress on TFP1 growth were highly significant. The second phase involved recalculation of the rental price of capital to estimate effects of the simulated tax incentives on capital formation and growth of TFP (= TFP2). As expected, the average annual share of capital in total cost with the tax incentives rose to 12% from 9% without the tax incentives. The average annual capital intensity also rose to real $15,263.70 with the incentives from real $10,402.91 without the incentives. Most importantly, higher capital formation, motivated by the tax incentives, raised aggregate quantity of the inputs significantly, leading to a slightly lower TFP2 than TFP1, because output was unchanged. In short, the data validated the hypothesis that tax incentives do indeed spur capital formation and TFP growth.     

Assessing the cost of fuel reduction treatments: A critical review

The basic costs of the operations for implementing fuel reduction treatments are used to evaluate treatment effectiveness, select among alternatives, estimate total project costs, and build national program strategies. However, a review of the literature indicates that there is questionable basis for many of the general estimates used to date. Different approaches to estimating cost have been used. Four methods are reviewed with discussion of the appropriate applications to fuel reduction cost analysis. Critical gaps identified in the understanding of operations costs include business overhead, repair and maintenance reserves, and estimates of the cost of risk. Future analyses of fuel treatments should be cautious in extrapolating cost numbers from the existing literature.     

Time consumption, productivity, and cost analysis of the motor manual tree felling and processing in the Hyrcanian Forest in Iran

An empirical time study was conducted to evaluate the per- formance of the current felling and tree processing methods used in Northern Iran’s Hyrcanian forest. Motor-manual felling is done mostly in winter, while tree processing starts when the felling season ends. We identified the elements of felling and processing work phases, and 142 cycles and 110 cycles were respectively recorded for felling and proc- essing. On the basis of data analysis (time study), we developed statisti- cal models of effective time consumption in the respective work phase and for its total productivity. The production rate of felling with and without delay time was 9.7 and 11.65 trees per hour (0.17 USD·m -3 and 0.21 USD·m -3 ), and the average production cost with and without delay was 1.21 USD and 1.45 USD per tree, respectively. The average produc- tivity of processing was 35 m 3 per effective hour and the average unit cost of processing was 0.22 USD·m -3 .     

Biomass production of Eucalyptus boundary plantations and their effect on crop productivity on Ethiopian highland Vertisols

In recent years, Eucalyptus globulus planted along field boundaries has come to dominate the central highland landscape of Ethiopia. Although evidence is scanty, there is a perception that this practice adversely affects crop productivity. An on-farm trial was conducted on Pellic Vertisol at Ginchi to determine the production potential of eucalypt boundaries and their effect on the productivity of adjacent crops of tef (Eragrostis tef) and wheat (Triticum sp.). The experiment comprised three stand ages, four field aspects and six distances from the tree-crop interface, using a split-split plot design with three replicates. Wood production rates ranged between 168 kg ha⁻¹ y⁻¹ (four years old) and 2901 kg ha⁻¹ y⁻¹ (twelve years). Thus eucalypt boundaries planted on a hectare of land would satisfy 50 to 75% of the annual biomass energy requirement of a rural household of five persons. Significant depression of tef and wheat yields occurred over the first 12m from the tree line: the reduction was 20 to 73% for tef and 20 to 51% for wheat, equivalent to yield losses of 4.4 to 26% and 4.5 to 10% per hectare respectively. Nevertheless, in financial terms, the tree component adequately compensated for crop yield reduction and even generated additional income. Therefore, eucalypt boundaries have great potential to satisfy the rising demand for wood, without requiring a major change in land use on the highland Vertisols. The greater availability of wood will reduce the demand for dung and crop residues for fuel, and thus may contribute to improved soil management on croplands while relieving the increasing pressure on indigenous forest and woodlands.     

Multispecies cropping systems in India: Predictions of their productivity, stability, resilience and ecological sustainability

Several traditional Indian cropping systems are used as examples of agriculture imitating the multispecies character of natural ecosystems. Modelling of their productivity and dynamics suggests they have potential advantages in production, stability of output, resilience to perturbation, and ecological sustainability, although they are harder to manage. Extra diversity in a cropping system can increase the production of a subsistence diet through either biochemical or ecological complementation. Stability of a cropping system may be improved through the incorporation of more crop species. Within a mixed crop, compensatory growth by the stronger component will tend to increase stability of final total yield. Where a two component intercrop has a regular production advantage, the land area required to produce a person s subsistence with a certain low level of risk of failure may be much less than if the crops are grown separately. Where a crop mixture contains contrasting components, the production penalty due to a disaster may be helpfully spread over time so that resilience of the system is increased. The compensatory growth of less-damaged components makes mixtures more resilient. Multi-species systems under intensification stress may be much less resilient than unstressed ones. Unless they are well managed, they can collapse. Where high output is desired, sustainability can only be attained through an understanding of the underlying processes. Intensification can lead to increased production up to a certain level, but such an increase is usually at the expense of subsequent production. This revised version was published online in June 2006 with corrections to the Cover Date.     

Hydraulic conductance, light interception and needle nutrient concentration in Scots pine stands and their relations with net primary productivity

Aboveground xylem hydraulic conductance was determined in Scots pine (Pinus sylvestris L.) trees and stands from 7 to about 60 years of age. At the stand scale, leaf area index and net primary productivity (NPP, above- plus belowground) increased and reached a plateau at about 25-30 and 15-20 years, respectively; both parameters declined in mature stands. Stand hydraulic conductance followed a similar trend to NPP, with a maximum at about 15-20 years and a pronounced reduction in old stands. At the tree scale, annual biomass growth per unit of leaf area (growth efficiency) declined with tree age, whereas aboveground sapwood volume per unit leaf area, which is linearly related to maintenance respiration costs, steadily increased. Radiation interception per unit leaf area increased significantly with reduced leaf area index of mature stands, despite increased foliage clumping in the canopies of mature trees. Needle nutrient concentration did not change in the chronosequence. Tree hydraulic conductance per unit leaf area was strongly and positively correlated with growth efficiency. We discuss our findings in the context of growth reductions in mature and old trees, and suggest that increased hydraulic resistance and maintenance respiration costs may be the main causes of reduced carbon gain in mature and old trees.     

Recent forest area increase in Europe: expanding and regenerating forests differ in their regional patterns,drivers and productivity trends

European Journal of Forest Research - In Europe, forest area is increasing. These recently established forests can be classified into regenerating after disturbances or expanding into agricultural...     

Age-related changes in foliar morphology and physiology in red spruce and their influence on declining photosynthetic rates and productivity with tree age

The contribution of changes in meristem behavior to age-related decline in forest productivity is poorly understood. We studied age-related trends in needle morphology and gas exchange in a population of red spruce (Picea rubens Sarg.) growing in a multi-cohort stand where trees ranged from first-year germinants to trees over 150 years old, as well as in grafted scions from these trees. In the field study, age-related trends in foliar morphology were determined in six cohorts ranging in age from 2 to 120 years, and differences in gas exchange characteristics were compared between 60- and 120-year age classes. In a common-rootstock study, scions from trees representing 20-, 60-, and 120-year cohorts were grafted onto juvenile rootstock and maintained for three growing seasons, after which morphological and physiological foliar attributes were evaluated. The field study revealed significant age-related trends in foliar morphology, including decreasing specific leaf area, and increasing needle width, projected area, and width/length ratio. Similar trends were apparent in foliage from the grafted scions. Both in situ foliage and shoots of grafted scions from the oldest cohort showed significantly lower photosynthetic rates than their counterparts from younger trees; however, differences in stomatal conductance and internal CO(2) concentrations were not significant. These results suggest that: (1) foliage of red spruce exhibits age-related trends in both morphology and physiology; (2) age-related decreases in photosynthetic rates contribute to declining productivity in old red spruce; (3) declines in photosynthetic rates result from nonstomatal limitations; and (4) age-related changes in morphology and physiology are inherent in meristems and persist for at least 3 years in scions grafted to juvenile rootstock.     

Ecosystem Productivity and Energy Flow of Three-Hardwood Forest

INTRODUCTIONTheresearch`vorkt`ascarricdoutinthcDaqingCentreofChail1eForcstBureau-NorthcastChina.Thcre-lhethree-hardt`oodforcstdistributedallttlebroadlyTheexistencc,movemcnt,dc\'clopl11cl1tanddynamicsofforestcommunitydePCndontheencrg3',energyflowandsubstan…     

Nutrients, moisture and productivity of established forests

The response of a forest to nutrient and moisture stresses is reflected in nutritional, physiological, and structural changes that include efficiency of nutrient use, translocation and cycling of nutrients, transpiration, retention of foliage, below-ground and above-ground allocation of carbon, as well as the structural development of the forest stand and its growth characteristics. This article reviews the relationship of forest ecosystems to nutrient and moisture stresses and addresses the means by which productivity can be enhanced by altering nutrient and moisture regimes.

Considerable research has focused on optimizing productivity by minimizing nutrient and moisture stresses. Research involved in nutrient additions has led to the use of commercial fertilizers to improve forest productivity. The results suggest that many forests are deficient in N and P and, to a lesser extent, S, K, Mg and trace elements. The duration of response for most nutrient additions is, however, relatively brief and the efficiency of the tree in using fertilizer is relatively poor. Long-term correction of nutrient deficiencies is seldom achieved with chemical fertilizers. However, N added through symbiotic fixation or, on a more limited scale, through addition of municipal and industrial waste by-products, can provide an excellent long-term growth response.

It is seldom feasible to change the moisture regime of a forest ecosystem through irrigation. However, field trials involving irrigation have demonstrated that moisture stress can limit productivity. There are various ways of minimizing moisture stress without irrigation, including mulching, removing ground-cover vegetation, and changing the spatial characteristics of the forest cover.

Research trials show that forest ecosystems will respond to moisture and nutrient additions; however, these responses and interactions between nutrients and moisture are typically poorly understood, and many questions remain unanswered: Does fertilization increase moisture-use efficiency of a forest or simply improve the nutrition of the site? Does improving the moisture regime of a site improve productivity primarily by decreasing moisture stress or by increasing nutrient availability and the rate of nutrient uptake? Is there a synergism in growth response with the addition of both nutrients and moisture? The linkages between nutrients and moisture appear inseparable and confound experimentation in this field. Answers to these questions and issues need to be found for the future development of plantation forestry.     

杨树苗期光合特征值与无性系产能相关性的探讨

木材产量是营林工作的终极目标,光合作用是叶绿体利用光合有效辐射将CO_2和H_2O同化为有机物质生产过程,探寻影响产量宏观指标的微观光合特征值,是杨树无性系育种工作的重要内容。为此,对湘林—90等7个杨树新、老无性系进行苗期光响应曲线测定,将暗呼吸速率等5个光合特征值与其主伐阶段的材积生长量作相关分析和逐步回归。在光合特征值中,暗呼吸速率与光补偿点呈紧密负相关关系;模拟光合作用白昼CO_2净同化总量与10年生材积生长量关系最为紧密,影响最大。按多元线性回归标准回归系数判断,各光合特征值对材积生长影响力的排序为:模拟光合作用白昼CO_2净同化总量光合速率光响应曲线实测值之和暗呼吸速率光补偿点光饱和点时最大光合速率。模拟光合作用白昼CO_2净同化总量或光合速率光响应曲线实测值之和可以作为杨树育种苗期选择的重要指标。     

Shade shoot structure and productivity of evergreen conifer stands

The current annual increment (wood volume) of stands of evergreen conifers on a research site in Sweden, was found to be significantly correlated with the maximum ratio of shoot to leaf silhouette area of shade‐acclimated shoots (R _max). Neither the slope nor the intercept of the regression was significantly different from that published earlier relating maximum mean annual increment of British stands to R _max ^. Moreover, a strong correlation between wood volumen increment and R _max also occurs when data from four countries are combined. Wood density was not significantly correlated with R _max. Harvest index for stand grown conifers more than 25 year old, was also not correlated with R _max. Estimated net biomass production (excluding fine roots) was significantly correlated with R _max (R ² = 0.82, F = 17.7). These new analyses could not be used to disprove the hypothesis that variation in shade shoot structure of evergreen conifers has a measurable effect on maximum biomass production.     

幼龄柞矮林林分结构及生产力评价

幼龄柞矮林林分生产力低，面积大，树种组成相对单一。其株数按径阶分布呈非正态分布，2cm,4cm径阶占大多数，公倾株数2000株以上出现枯损，以榛子柞林这一类型林分生产力最高，胡枝子林型生产力最低。