engleski

Discrete choice analysis of forest inventory plot types in Croatian uneven-aged forests

Reliable forest inventory is a basis for sustainable forest management. Forest inventory basically consists of terrestrial measurement being done on sample plots. Choice of sample is an essential component of forest inventory that has to ensure sound results by means of precision and accuracy. Balance between available resources (money, time) and results is always demanding task that has to be taken into account. As a part of investigation on sample plot type that could optimize efficiency by ensuring best possible results at minimum cost, a questionnaire has been carried out among 60 forest inventory experts in Croatia. Seven previously field-tested circular plot types were proposed for expert evaluation: 250 m2, 500 m2, 750 m2, concentric plot 78, 5/452, 4 m2 , concentric plot 254, 5/615, 8 m2 , concentric plot 153, 9/530, 9/1256, 6 m2 and factor 3 Bitterlich plot. Experts were asked to chose appropriate plot type(s) and confirm their choice by addressing aspects of chosen type: simplicity, reliability, familiarity, expert recommendation and cost. Answers were analysed by discrete choice analysis considering groups of experts by institution and age. Reliability, cost and efficiency of listed methods obtained by field check were later compared to experts’ attitudes from questionnaire. Most of the experts prefer familiar and more used methods, especially experts from state forest company. Experts from other institutions and private companies in addition to well known would also accept improved and more complex types as concentric plots. On the other hand, most experts think of reliability as the most important aspect, followed by cost and simplicity. Reliability is even more important for experts from private companies and scientific institutions. For these experts simplicity is the least important aspect, unlike state experts who favor simplicity as much as reliability. Younger experts, unlike the older ones, have an inclination to favor recommendation of colleagues in their choice. Although experts would chose methods that are familiar with, it is interesting that familiarity is generally assessed as being the least important aspect. Case study results on efficiency support the choice of 500 m2 plots, favoring also concentric type plots that were mostly neglected by the experts. Improvement of the forest inventory is continuous and ever lasting task aiming at better efficiency. Better suited plot types could significantly contribute to that aim. However, since implementation of plot type relies on people doing field measurements, their experience, knowledge and attitudes should be taken into account when changes in inventory system occur.

forest inventory; questionnaire; uneven-aged forests; discrete choice analysis

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