In order to consider forest biomass as a real alternative for energy production, it is critical to obtain accurate estimates of its availability using non-destructive sampling methods. In this study, we estimate the biomass available in a Scots pine-dominated forest (Pinus sylvestris L.) located in Spain. The biomass estimates were obtained using LiDAR data combined with a multispectral camera and allometric equations. The method used to fuse the data was based on back projection, which assures a perfect match between both datasets. The results present estimates for each of the seven different biomass components: above ground, below ground, log, needles, and large, medium and small branches. The accuracy of the models varied between R2 values of 0.46 and 0.67 with RMSE% ranging from 15.72% to 35.43% with all component estimates below 20%, except for the model estimating biomass of big branches. The models in this study are suitable for the estimation of biomass and demonstrate that computation is possible at a fine scale for the different biomass components. These remote sensing methods are sufficiently accurate to develop biomass resource cartography for multiple energy uses.

Airborne Laser Scanning (ALS) is widely extended in forest evaluation, although photogrammetry-based Structure from Motion (SfM) has recently emerged as a more affordable alternative. Return cloud metrics and their normalization using different typologies of Digital Terrain Models (DTM), either derived from SfM or from private or free access ALS, were evaluated. In addition, the influence of the return density (0.5–6.5 returns m^-2) and the sampling intensity (0.3–3.4%) on the estimation of the most common stand structure variables were also analysed. The objective of this research is to gather all these questions in the same document, so that they serve as support for the planning of forest management. This study analyses the variables collected from 60 regularly distributed circular plots (r = 18 m) in a 150-ha of uneven-aged Scots pine stand. Results indicated that both ALS and SfM can be equally used to reduce the sampling error in the field inventories, but they showed differences when estimating the stand structure variables. ALS produced significantly better estimations than the SfM metrics for all the variables of interest, as well as the ALS-based normalization. However, the SfM point cloud produced better estimations when it was normalized with its own DTM, except for the dominant height. The return density did not have significant influence on the estimation of the stand structure variables in the range studied, while higher sampling intensities decreased the estimation errors. Nevertheless, these were stabilized at certain intensities depending on the variance of the stand structure variable.

The European Union (EU) ensures the conservation of biodiversity through the Natura 2000 Network, which establishes the classification and selection of protected areas at European level. Unfortunately, member countries cannot make the best zoning decisions for biodiversity conservation because there are no clear and uniform parameters to designate Natura 2000 sites. Due to this, it is convenient to evaluate the importance of the criteria for biodiversity conservation through a general assessment, which could establish relevant criteria that can be analysed through geostatistical methods combined in multicriteria analysis. This paper aims to consider biodiversity importance values taking into account land use, so that it is possible to develop a zoning proposal which verifies or corrects the suitability of the designated areas for the Natura 2000 Network in Castilla y León, Andalucía and Madrid (Spain). The choice of these regions allows us to compare areas with a high variability of population density, making possible to compare the potential protected areas with respect to the population living in each area. This assessment has been performed using basic and easily adaptable criteria of biodiversity conservation, so it could be applied in other European territories. In this way, clear and uniform parameters for zoning will be used, being possible to detect the best protected areas. One of the most important purposes of the Natura 2000 Network is to increase connectivity between territories; our work proposes new areas that could be linked to currently protected territories, to favour the achievement of this purpose of the Natura 2000 Network.