Evaluation of two silvicultural treatments and terrestrial photogrammetry in Quercus suber stands, North-East Spain

Abstract

Cork oak (Quercus suber) is a highly appreciated tree in Mediterranean forests for its values: economic and environmental. Cork extraction is the main activity due to the economic value of the cork. For this reason, this project has the aim to promote the sustainable production of cork. The first objective has been a comparison between two silvicultural treatments. The silvicultural treatments tested were: total and partial clearing combined with a selective thinnig of low intensity, to consider advantages and disadvantages of each scenario. Knowing pros and contras, we wanted to make a general management proposal depending on the target wanted for the cork oak forest. The second aim, related with the first one, has been evaluating the utilization of a technic called terrestrial photogrammetry or 3D photogrammetry, to reduce costs and gather data as diameter or cork caliper faster. Both aims are related because this project tries to search a reduction of costs in data collection and an increment of revenues producing more cork. Parameters studied to compare both treatments are tree size, cork production, biodiversity, fire, work, costs and young individuals. It has been possible to observe that total clearing is better in fire and young individuals, while partial clearing wins in all the other features. About terrestrial photogrammetry, it consists in taking photos of a plot to process them later and create a 3D model. From this model, it is possible to collect data using a computer. This allows a reduction of costs and permits a faster data obtaining. It has been observed that in dense forests it is not possible to use this technology due to a lack of reference points. However, in forest with low density, the point cloud obtained respects the real shape and proportions, so it is possible to collect data from it. For that reason, in low density forests, we propose a partial clearing using terrestrial photogrammetry to gather data, because we would have a higher economic yield without compromising forest health