Borz S.A., 2017. Performance of a mid-sized harvester-forwarder system in integrated harvesting of sawmill, pulpwood and firewood. Ann. For. Res. 60(2): 227-241.Abstract. Fully mechanized timber harvesting systems are generally characterized by a high operational performance being widespread and used across many regions. Such systems are adaptable to different levels of operational integration, enabling also the recovery of energy wood, but given integration configurations affect their performance. A production study was carried out in a Norway spruce clear-cut aiming to investigate the performance of a mid-sized harvester-forwarder system in general, and the effect that fuelwood recovery from tree tops may have on its performance. Data was collected in the field during 11 days of observation using state-ofart equipment and software. Harvester's operations were monitored using a digital camera. Data refined from 27.5 filmed hours that accounted for 1045 felled and fully processed trees was used to model and compute its performance indicators. In addition, fuel consumption data was sampled in the field. The results indicated that a delay-free cycle time consumption was affected by variables characterizing the tree size. The net production rate was estimated to about 26.5 m 3 • h -1 , being substantially affected by supplementary tree-top processing. Forwarding operations were monitored using a handheld computer and a Global Positioning System unit. The delay-free cycle time consumption was affected by forwarding distance and the amount of loaded wood, resulting in a net production rate of about 19.2 m 3 • h -1 . Under these circumstances, the forwarding performance matched the harvester's outputs for an extraction distance of about 100 m, indicating that the supplementary processing of the tree-tops had no effect on the system's productive performance in the studied conditions. Most likely, it affected the harvester's fuel consumption given its proportion of 9% in the delay-free harvester's cycle time. The results also indicated a mean fuel consumption of about 1.7 l • m -3 for the studied harvesting system.

Abstract. Time studies represent important tools that are used in forest operations research to produce empirical models or to comparatively assess the performance of two or more operational alternatives with the general aim to predict the performance of operational behavior, choose the most adequate equipment or eliminate the useless time. There is a long tradition in collecting the needed data in a traditional fashion, but this approach has its limitations, and it is likely that in the future the use of professional software would be extended is such preoccupations as this kind of tools have been already implemented. However, little to no information is available in what concerns the performance of data analyzing tasks when using purpose-built professional time studying software in such research preoccupations, while the resources needed to conduct time studies, including here the time may be quite intensive. Our study aimed to model the relations between the variation of time needed to analyze the video-recorded time study data and the variation of some measured independent variables for a complex organization of a work cycle. The results of our study indicate that the number of work elements which were separated within a work cycle as well as the delay-free cycle time and the software functionalities that were used during data analysis, significantly affected the time expenditure needed to analyze the data (α=0.01, p<0.01). Under the conditions of this study, where the average duration of a work cycle was of about 48 seconds and the number of separated work elements was of about 14, the speed that was used to replay the video files significantly affected the mean time expenditure which averaged about 273 seconds for half of the real speed and about 192 seconds for an analyzing speed that equaled the real speed. We argue that different study designs as well as the parameters used within the software are likely to produce different results, a fact that should trigger other studies based on variations of these parameters. However, the results of this study give an initial overview on the time resources needed in processing and analyzing the data, and may help researchers in allocating their resources.

A literature review on harvester and forwarder equipment was conducted using the open access international scientific databases. The aims of this study were to evaluate the main interests of different research topics elaborated in 28 countries around the world in the last 23 years. The time span of the main articles ranged from the beginning of the year 1990 to end of 2012. The evolution trend of research topics was analyzed for this time period in order to relate them to possible future research directions in Romania. Most of the used literature was extracted mainly from scientific journals and conference proceedings, summing up a total of 105 references that were further analyzed. As expected, the synthesis of the references, pointed out that most of the interests and attention of the scientists has been given to productivity, costs and time expenditure on one hand, followed by studies on soil impact, environment and tree damage on the other hand. Topics referring to fuel-lubricants consumption and computer simulations didn't had the same impact among the researched literature, accounting for the smallest number of the cited articles. The obtained results will fill in the gap in future research by using scientific approaches particular to the Romanian conditions.