A model to predict productivity of different chipping operations

The chipping operation is an important component of harvesting systems producing biomass and pulp chips. This paper aimed to develop a valid model to predict the productivity of chipping as part of these operations. Over a number of years more than 200 different time studies were conducted on chipping operations in Italy and Australia. Multiple regressions and backward stepwise data analysis methods were applied to develop a productivity prediction equation, considering the following variables: machine power (kW), piece size (m³), crew size, harvesting method, species, tree part, wood condition, wood lay-out, chipping type, propulsion, feeding method, point of chipping, season, location of chip discharge, country (Italy or Australia) and type of operation (biomass chip operation or pulp chip operation). The final productivity model included machine power, average piece size, location of chip discharge and type of operation as significant variables. The internal validation test was conducted using five witness samples from Italy and Australia, which confirmed the validity at α=0.05. Additional international case studies from North America, South America, and central and northern Europe were used to test the accuracy of the model, in which 15 studies confirmed the model's validity and two failed to pass the test.     

Application of a Small-Scale Equipment System for Biomass Harvesting

The small-scale harvesting equipment system has been and continues to grow in use in forestry operations in some regions in the world. This harvest system can include a range of equipment types, such as feller-bunchers or chainsaws, skidders or farm tractors, and chippers. These machines are generally smaller, lower cost and less productive than larger, more advanced forestry machines. The objective of this project was to investigate the feasibility of a small scale harvesting system that would produce feedstock for a biomass power plant. The system had to be cost competitive. A boom-type feller-buncher, a small grapple skidder and a chipper were tested as a small-scale system. In this study, feller-buncher and skidder productivity was determined to be 10.5 m³ per productive machine hour, and production for the chipper was determined to be 18 m³ per productive machine hour. Production from the system did not reach the desired levels of 4 loads/day (25 m³/load); however, the system was able to produce about 3 loads/day. The results showed that the system currently could fill a roadside van for $16.90/m³, but suggested machine modifications could potentially reduce the system cost to $12.73/m³. Residual stand damage was minimal, especially on flatter ground and not operating on a slash layer. Soil disturbance from the harvesting system was predominantly undisturbed or classified as a shallow disturbance.     

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.     

A Comparison of Productivity in Five Small-Scale Harvesting Systems

The use of small-scale harvesting equipment continues to grow in forestry in many regions of the world. This equipment includes various devices and methods used to harvesting that generally are smaller, less expensive and less productive than advanced forestry machines. The objective of this study is to compare the efficiency of five alternative extraction methods implemented in a harvesting unit located in a mixed beech and oak forest ecosystem in northwestern Turkey. A continuous time study was conducted during primary transport operations that included skidding with animal power, skidding with farm tractor, hauling with farm tractor, hauling with forest tractor, and extraction by skyline. Timber was skidded uphill on a skid trail, and an average skidding distance of 100 m for all haulage methods was considered. Average slope of the harvesting unit ranged from 20 to 40 %. Average productivities for respective haulage methods were 3.80, 6.25, 2.80, 5.25 and 10.09 m³/h. Significant differences were found between productivity of haulage methods using one-way analysis of variance. The extraction by skyline, skidding with farm tractor, and hauling with forest tractor were determined to be the most statistically different methods, the productivity of these methods was found significantly higher than the other methods. Skid trails are useful for shortening distances during forest operations and skidding with farm tractor is a productive method in small-scale forestry of Turkey.     

Harvesting alternatives for mallee agroforestry plantations in Western Australia

The authors tested two harvesting systems especially designed for mallee agroforestry plantations on farmland. Both systems were based on versatile forest technology commonly used for conventional logging operations. They differed especially for the felling technology: small-scale drive-to-tree or industrial swing-to-tree equipment. Both systems were tested side-to-side on 12 experimental plots each. The resulting harvesting cost was 22 and 27 AU$ t^?1, for the industrial and the small scale system, respectively. Chipping represented between 60 and 80 % of the overall harvesting cost, and offered much room for improvement. The industrial system always offered the lowest harvesting cost, regardless of annual usage, when equipment mobilisation costs were not considered. The productivity of conventional forestry equipment was strongly dependent on belt stocking and tree size. If the diameter at ankle height dropped below 10 cm, economic viability decreased very rapidly.     

A model to estimate available timber and forest biomass and reforestation expenses in a mountainous region in Japan

We developed a model to estimate supply potentials and available amounts of timber and forest biomass resources from profitable sub-compartments of thinning and final felling operations. Economic balances were estimated while considering not only harvesting expenses but also reforestation expenses after final felling, which should be considered for sustainable forest management. Harvesting expenses were estimated based on two types of timber harvesting systems and three types of forest biomass harvesting systems in each sub-compartment. Then, the model was applied to Nasushiobara city of Tochigi prefecture, Japan. Reforestation expenses had large negative impacts on the financial balances of final felling operations. Few sub-compartments were profitable after considering reforestation expenses. Most profitable sub-compartments were those with mechanized operation systems and landing sales. These accounted for 17.19% of all sub-compartments, while only 5.75% of the sub-compartments were profitable based on their current operation systems and landing sales. Although the overall supply potentials of timber and forest biomass resources were 380,000 m3 and 210,000 Mg, respectively, and 15 times the planned harvest of coniferous tree volume of 25,000 m3year-1 and 50 times the annual demand for the woody gasification power generation of 4,000 Mg year-1 in Nasushiobara, available amounts of timber and forest biomass resources were only49,429 m3 and 33,333 Mg, which were 13.0% and 15.7% of supply potentials for landing sales with mechanized operation systems.     

Productivity and cost of whole‑tree harvesting without debarking in a Eucalyptus nitens plantation in Tasmania,Australia

There is increasing interest worldwide in using tree harvesting biomass as an energy source. Bark retained on logs is commonly used as an energy source, but is generally removed from eucalypt logs during harvest. In order to evaluate the potential use of eucalypt bark as fuel, there is a need for information on the productivity and cost implications of retaining eucalypt bark during harvest operations. The study examined the impact of retaining bark on logs on the productivity and costs of a whole?tree to roadside harvesting system in a short?rotation Eucalyptus nitens plantation in Australia being harvested for pulp logs. Trees were felled and bunched with a feller?buncher in spring, then left infield for four weeks to promote bark adhesion and reduce bark loss. A skidder extracted the trees to roadside where a processor processed them to predominantly 10?m logs. Machine productivities were calculated from estimated tree and log volumes and cycle times recorded from video recordings. The feller?buncher's productivity (65 m3 PMH₀^?1) was less than expected as it appeared to be underpowered to handle the larger trees on the study site. The skidder's productivity (56 m3 PMH₀^?1) was comparable to those reported in studies under similar conditions and with bark retained. The roadside processor's productivity (25 m3 PMH₀^?1) was lower than expected. This was believed to result from the operator separately stacking 10?m and 5?m logs, and the lower feed speed resulting from slippage due to the reduced feed roller pressure used in the study to reduce bark loss. Future research could identify feed rollers that increase feed speed while retaining bark. Harvest system costs (AUD18 GMt^?1) were similar to those reported for a eucalypt roadside processing trial where bark was removed. These results suggest that retaining bark on the logs at roadside did not affect the harvesting system's productivity or costs.     

Productivity and cost analysis of semi-mechanised and mechanised systems on the Viphya forest plantations in Malawi

At least 200 000 m³ of timber is harvested annually using semi-mechanised harvesting systems on the Viphya forest plantations in Malawi. Although these systems have long been used on the Viphya, no investigation on their productivity has so far been reported. Additionally, the absence of localised productivity analyses in Malawi has created a paucity of information on appropriate timber harvesting systems for production maximisation and cost minimisation. The objective of this study was to compare the production rates and operational costs of chainsaw/grapple skidder (semi-mechanised) and feller-buncher/grapple skidder (mechanised) harvesting systems in order to determine the economic feasibility of mechanised systems in the Viphya forest plantations. The study was conducted in Pinus kesiya compartments at the Kalungulu and Champhoyo forest stations of the Viphya forest plantations. A work study approach was followed to capture harvesting time and volume data for the semi-mechanised system. Secondary work study data were used to simulate productivity of the mechanised system on similar compartment conditions. A timber-harvesting costing model was used to analyse the results. The study showed that the simulated mechanised system was associated with lower operating costs and inventories with higher production rates than the semi-mechanised system. The cost marginal difference was US$0.89 m^–3. It was therefore established that migration to mechanised systems could optimise timber harvesting productivity on the Viphya in future, if optimal volumes are available to ensure the efficient application of the mechanised harvesting system.     

Estimating biomass and macronutrient content of some commercially important plantation species in South Africa

The removal of biomass, in any combination of stemwood, bark or branch harvesting, can cause a significant increase in nutrient loss from commercial timber plantations. Ensuring long-term site productivity of forest plantations is a key issue for forestry management. Managers need to secure a continued supply of tree biomass components, while understanding the impact of various harvesting operations on plantation nutrient reserves. It is imperative to quantify the biomass and nutrient stocks and their removal during silvicultural operations, such as harvesting, burning and various forms of site preparation. At present, there are no simple methods to estimate inherent site nutrient reserves, or nutrient gains through processes such as atmospheric deposition or rock weathering, or the quantities of nutrients lost through silvicultural operations (harvesting, burning and site preparation). The aim of this work was to construct simple multipliers that can be used in conjunction with plantation timber volumes to estimate stem, branch and bark biomass and nutrient contents. The multipliers were developed from data existing for Eucalyptus spp., Pinus patula and Acacia mearnsii stands throughout the summer rainfall region of South Africa and Swaziland. Due to limited data unique nutrient multipliers were not developed for each productivity range and the multipliers were assumed to be consistent across all productivity ranges. The ratios may underestimate on fertile sites where luxury consumption of nutrients may occur and not accurately predict where stand management practices have altered wood density, allometry or canopy architecture. Although genus and species impacted on the quantity of nutrients held in the plantation biomass, productivity and harvesting intensity were the biggest driver of nutrient removal. Although the multipliers developed here have value in creating a general estimate of nutrient content they are from a limited dataset and need to be expanded upon across species, site and age ranges before being able to precisely estimate nutrient contents. Although harvesting is a major component of nutrient export, natural additions and losses of nutrients, and site nutrient reserves need to be known in order to gain a complete understanding of the impact of nutrient loss on site nutrient reserves.     

A bioeconomic analysis of carbon sequestration in farm forestry: a simulation study of Gliricidia sepium

Trees provide many environmental services including improved soil fertility and soil structure, which often leads to increased productivity and sustainability of the land. Trees also increase the average carbon stocks of land-use systems. Under the Clean Development Mechanism of the Kyoto Protocol, landholders may receive payments for the carbon-sequestration services provided. This study is the first of a series aimed at assessing the appropriateness of tree-based land-use systems as alternatives to continuous cropping and/or Imperata-fallow systems. The performance of a Gliricidia sepium woodlot, grown over 25 years and under various pruning and harvesting regimes, was assessed through modelling. The assessment was based on the system’s ability to sequester and store carbon, maintain land productivity, and be financially profitable for landholders. It was found that the system was profitable under most management regimes tested. Profits were maximised by pruning and harvesting as much biomass as possible when no carbon payments were available, but this strategy decreased system productivity and profitability in the long run. Carbon-sequestration payments encouraged landholders to adopt less intensive practices since net revenues were higher with carbon payments. It was also shown that the carbon pools included in a carbon-trading scheme were sensitive to carbon-measuring costs. For example, if the annual cost of measuring soil carbon was greater than US$1.19 ha⁻¹ it would not be economical to account for this pool in a carbon-sequestration project.     

Time Consumption and Production Costs of Two Small-Scale Wood Harvesting Systems in Northern Greece

A field-based study was carried out to determine the productivity and production cost of the tree length (TL) and the wood assortment (WA) systems implemented under small-scale forestry conditions in two Scots pine stands in Northern Greece. Tree felling and processing productivity were estimated at 8.64 m³ per productive machine hour (PMH^?1) and 10.21 m³ PMH^?1, respectively. Wood felling and processing times were strongly dependent on dbh and total tree volume. However, when manual debarking was also considered the productivity rates decreased to 1.96 and 1.43 m³ PMH^?1, respectively. Skidding productivity was calculated to be 3.35 m³ PMH^?1 for TL and 7.17 m³ PMH^?1 for WA, respectively. Strong correlations have been found between the net skidding time and (a) the skidding distance and (b) the load per turn in both wood harvesting systems. Production costs varied greatly, from 19.38 € m^?3 up to 44.81 € m^?3 of roundwood depending on the harvesting system and the inclusion of debarking. The findings suggest that the WA system is more efficient in terms of productivity and production cost than TL, and that there is a substantial optimization potential. The optimization potential can be encoded in four suggestions: (a) opening up of more forest roads to reduce high skidding times, (b) replacement of manual debarking by mechanical debarking at the sawmill, (c) replacement of old pieces of equipment with newer ones and (d) training of the existing workforce.     

Machine productivity and residual harvesting residues associated with a cut-to-length harvest system in southern Tasmania

The cut-to-length method is a preferred method for harvest of pine plantations in Australia. The cut-to-length method studied in southern Tasmania consists of a feller-buncher, processor, forwarder, grapple loader and tractortrailers that were producing only pulp logs for the plantation owner Norske Skog. An elemental time study method was applied to evaluate the productivity of the machines within the flat terrain, Pinus radiata plantation. Multiple regression was used in SPSS to develop the productivity prediction models. The productivity of the feller-buncher and processor averaged 122.20 m³ per productive machine hours excluding all delays (PMH₀) and 84.32 m³ PMH₀ ^?1, respectively. The average productivity for the forwarder, grapple loader and truck were 80.90 m³ PMH₀ ^?1, 100.80 m³ PMH₀ ^?1 and 27.40 m³ PMH₀ ^?1, respectively. The average fuel consumption of the feller-buncher, forwarder and processor were also documented. The trial assessed harvest residue left on the site and found 238.7 GMt ha^?1 (31% of total biomass above the stump) was left of which 46% was stemwood. These research findings can be used for harvesting planning and improving logging efficiency.     

Effect of pruning frequency and pruning height on the biomass production of <Emphasis Type="Italic">Tithonia diversifolia</Emphasis> (Hemsl) A. Gray

Addition of tree or shrub prunings through alley cropping or biomass transfer systems have contributed to sustainable land-use systems in the tropics. Long term productivity of biomass transfer systems require shrub or tree species that coppice after cutting to provide sufficient plant nutrients. The effect of pruning frequency and cutting height on the biomass production of Tithonia diversifolia was studied to provide information for managing hedges. Results showed that height of cutting, pruning frequency, and their interactions significantly affected dry matter production of T. diversifolia. The results also showed that a significantly higher biomass production could be produced when Tithonia was pruned at long time intervals. Pruning height was also of importance in the harvesting of Tithonia biomass and it was evident that dry matter production was highest when Tithonia was pruned bimonthly at 50 cm height. With bi-monthly pruning frequency, dry matter production could be as high as 7.2 t ha⁻¹ yr⁻¹ which might be a sufficient biomass to improve soil productivity in biomass transfer systems.     

Assessment for Improvement: Harvesting Operations in Small-Scale Forest on Thai Steep Terrain

Timber harvesting on steep terrain is always a challenge in terms of safety, operating costs, and environmental impact. The motor-manual, cut-to-length method is the most common in harvesting operations in the mountainous areas of Thailand. The motor-manual operations are characterized by various negative features such as high fatality rates, expensive operating costs, and low productivity. The aims of this study were to evaluate the prevailing harvesting operations, to propose new working methods and systems, and to suggest work safety improvement measures. The results indicated an extremely high fatality rate in Thailand compared to the average in other countries. Possible reasons for this may include ineffective safety regulations, inadequate worker training programs, seasonal forestry workers, and a lack of personal protective equipment. Consequently, alternative working methods have been suggested as a system. The proposed working method was intended to improve work safety, enhance productivity and reduce operating costs using by simulation to find best solution. Shifting from a cut-to-length to tree-length processing and moving forward to mechanization was introduced as alternative harvesting systems. The results showed that partly-mechanized systems would significantly improve the productivity. Potential work safety improvement measures may consist of adequate training, personal protective equipment, and technological improvement. Obstacle for implementation is the high investment for forest machines and silvicultural practices.     

Effects of harvesting on the biomass of plant species

In South China's Guangdong Province, like other parts of the developing world, most vegetation undergo heavy harvesting for domestic fuel. A few villagers in Hong Kong still collect biomass from hillsides for cooking. Two experiments in Hong Kong and two observations in Guangdong were conducted in grasslands and shrublands to examine the effects of three experimental harvesting frequencies on the biomass of dominant species and to observe the impacts of long-term practical harvesting on the biomass of dominant species. Over 2 years of harvesting experiment, the range of the aboveground biomass of six individual dominant species changed from 26–154 g m⁻² to 6–135 g m⁻² on Hong Kong experimental site 1 and from 14–875 g m⁻² to 3–207 g m⁻² on Hong Kong experimental site 2. Biyearly harvesting did not significantly reduce the aboveground biomass of dominant species, but yearly and half-yearly harvesting did so. The aboveground biomass in the half-yearly harvested treatment was higher in August than in February. The uncut hillsides gave higher aboveground biomass than the often-cut hillsides in Guangdong. The six dominant species together at the Hong Kong and Guangdong sites contributed over 75% to the aboveground biomass of the vegetation. The plant species scarcely changed their percentage biomass contributions with seasons.     

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).     

A comparison between excavator-based harvester productivity in coppiced and planted Eucalyptus grandis compartments in KwaZulu-Natal,South Africa

Due to the labour challenges in South Africa, mechanised forestry equipment has increasingly been required to operate in complex forest conditions – such as coppiced Eucalyptus compartments – where they have not operated before. For this reason, harvesters are either used in certain coppiced compartments with uncertain productivity expectations, or harvesters are not used in these compartments due to a lack of productivity knowledge. This research aimed to determine the influence of tree volume and tree form on the productivity of an excavator-based harvester in coppiced regrowth – with either double or single stems, or planted single stems – in Eucalyptus grandis pulpwood compartments. In addition, the stem felled first and the distance between stems were investigated for coppiced double stems. The stem felled first is whichever stem between the two coppiced double stems the harvester grabbed, felled and processed first. The tree volume was determined; thereafter the trees were classified into different form classes. The tree volume and the cycle time were used to determine productivity. The research results showed that planted trees had the highest productivity across all tree sizes, followed by coppiced single stems and then coppiced double stems. When harvesting a 0.2 m³ tree, the mean harvester productivity was 8.7 m³ per productive machine hour (PMH₀) in coppiced double stems, 13.8 m³ per PMH₀ in coppiced single stems and 16.1 m³ per PMH₀ in planted trees. In coppiced double stems the productivity was significantly influenced by the size of the stem felled first. In coppiced double stems the productivity was not significantly influenced by the distance between stems. The productivity for both coppiced single stems and coppiced double stems was significantly influenced by stem form. The poorly formed trees had lower productivity compared to the trees with good form.     

Productivity of successive rotations of Acacia mangium plantations in Sumatra,Indonesia: impacts of harvest and inter-rotation site management

The impacts of wood harvest, biomass removal and inter-rotation site management practices on productivity of Acacia mangium in South Sumatra were studied over 12 years across successive rotations. The productivity measured as MAI increased from 29.4 m³ ha^?1 year^?1 in the first to 48.0 m³ ha^?1 year^?1 in the second rotation. Whole tree harvesting (total stem, branches and leaves) caused a 21 % reduction in volume compared to harvesting merchantable wood alone in the next rotation. The rates of nutrients accumulation in trees were highest during the first year of growth, and declined from age 2 years. Significant amounts of nutrients were recycled through litter fall from 1 year after planting. Results highlight the importance of management which promotes nutrient supply on stand growth. Removal of slash and litter lowered soil pH, by about 0.1 unit. A small reduction was also found in soil organic carbon and nitrogen in the top soil during the first 3–4 years but values returned to pre-harvest levels by the end of the rotation. Extractable soil phosphorus and exchangeable cations decreased by the end of second rotation but these measures underestimate the nutrient pools available for A. mangium. These findings along with results from other studies have helped to implement operations which promote conservation of site resources for sustainable production in the region.     

Is the productivity decline in Norway spruce following whole-tree harvesting in the final felling in boreal Sweden permanent or temporary?

The growing demand for renewable energy sources in Sweden has resulted in an increased use of forest biomass that now includes logging residues. However, concern has been raised that the moderate increase in biomass removal associated with whole-tree harvesting results in a significant increase in nutrient removal, which in turn has a negative effect on future forest growth. Productivity over 31 years in planted Norway spruce (Picea abies (L.) Karst) in northern Sweden following three different harvest intensities is reported from a field experiment with exceptionally large growth reductions following whole-tree harvest. The three harvest intensities were applied in a randomized block design with four blocks: (i) conventional stem-wood harvest up to a top diameter of 5 cm (CH); (ii) whole-tree harvest of all above-stump biomass (WTH); (iii) branch and stem harvest with needles left on site (BSH). Recovery rate of biomass was almost 100% and the logging residues left were evenly spread over the 25- by 25-m experimental plots. Stand growth was negatively affected by WTH: basal area after 31 years was significantly lower following WTH (10.5 m² ha⁻¹) as compared to CH (14.0 m² ha⁻¹, p = 0.005) and BSH (14.2 m² ha⁻¹p = 0.003). Annual height growth of a sub-sample of trees (10 undamaged trees per plot, or 40 per treatment) was used to estimate and compare long-term effects on site productivity. This showed that stand growth loss resulted from a significant but temporary reduction in site productivity on WTH plots over a 5-year period (years 8-12, 1984-1988). Nitrogen is the major growth-limiting nutrient in boreal Swedish forests, and the N-content of needles during that period suggests that the temporal reduction in site productivity (i.e., stand growth) was primarily due to increased nitrogen loss with WTH.     

Effects of harvesting on productivity of bay leaf tree （Cinnamomum tamala Nees ＆ Eberm）： Case from Udayapur district of Nepal

Cultivation of bay leaves （Cinnamomum tamalaNees ＆ Eberm） to fulfil household income needs is a long established practice in Udayapur district of Nepal. The practices adopted by farmers for bay leaf harvesting have not, however, been validated by scientific investigation for their sustainability. To investigate the impacts of harvesting on the yield of branch, leaves and biomass of leaves, a two-year research project was conducted in farm fields at Kopche village of Routa VDC in Udayapur district, Nepal. Four different harvesting treatments, the orien-tation and the order of branches were taken as independent variables to test their effects on number of branches, leaves and biomass of leaves. Orientation, harvesting treatments and order of branches had a significant effect on the number of branches, but not on the number of leaves or biomass （fresh and dry weight） of leaves in the year of harvest. Between two consecutive harvests there was no significant difference in the num-ber of branches, leaves or biomass. Lower two-thirds portion of the trees produced the largest number of leaves and branches of the fourth order in both years. Therefore, lower two-thirds portion of the trees were suitable for harvesting. Our findings support farmer experience that no change in productivity of leaves is observed when harvesting each year. For long term sustainability, harvesting should be conducted without debarking of trees or damage to branches. Our findings could be extrapolated to and tested in other areas with different access and user rights where the rota-tion for harvest is fixed or regulated without research evidence.