Models that allow a quantitative characterization of the forest stand, with some detail, can provide precious information for the decision-making processes involved in forest management. In the frame of the SelPiBio LIFE+ project (www.selpibio.eu, LIFE13 BIO/IT/000282) a very detailed database, with more than 4.700 fully measured and geo-referenced Pinus nigra J.F. Arnold trees, characterising the stands before interventions, has been published as open data source (DOI 10.1007/s13595-017-0648-8). Measures concerning crown and stem have been taken using a non destructive method, by means of an optical relascope and the Field Map technology. Intervention characteristics have successively been recorded updating the archive. Exploiting this knowledge base many different modelling efforts have been developed. This contribution presents three equations, modelling crown shape, potential crown width and stem taper. The crown profile equations model the variation of crown radius of as a function of the distance from the top. The analysis has been carried out dividing the crown, at the height of the largest crown width, into an upper part (that exposed to the sunlight) and a lower portion (the shaded part of the crown). The taper model was fitted on a subset of trees whose stem has been intensively sampled (every metre), from the ground to the top. Finally the potential crown width has been studied, modelling the maximum crown radius as a function of the diameter at breast height, based on observations from freely-growing trees. All three models are characterized by statistical significance with adjusted-R squared higher than 0.7. Equations usefulness as forest management tools has been also evaluated by simulation. Management objectives must jointly consider the need to improve ecological functionality of the stand as well as silviculture economics. Taper functions help the identification of the most profitable allocation of timber assortments, while the crown equations offer the basis for the development of local thinning guides (e.g. ‗Crown Competition Factor'). The latter have been used to simulate the selective thinning actually performed and documented as database update. More than 95% of trees marked by forest technicians were correctly identified using the proposed models. Results of this kind can hence be of great practical value as forecasting and guiding tools, of course they can not fully substitute the technician and his holistic judgement.
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|Titolo:||Crown and stem taper equations for Pinus nigra J.F.Arnold as forest management operational tools|
|Data di pubblicazione:||2018|
|Appare nelle tipologie:||4.2 Abstract in Atti di convegno|