Rafael Alonso Ponce

A novel application of the ecological field theory to the definition of physiographic and climatic potential areas of forest species

A new approach to the definition of physiographic and climatic potential areas for forest species, based on the ecological field theory, is outlined in this paper. The proposed formulation is tested on the Spanish juniper (Juniperus thurifera L.), using data from 883 permanent and temporary plots throughout its distribution area in the Spanish autonomous region of Castilla y León. The suitability of the territory for the species is assessed by previously studying its habitat, which in turn is analyzed through physiographic and climatic parameters. This new method is rooted in an additive index that depends on the Mahalanobis distance in the parametric space that evaluates the ecological resemblance between the studied site and each of the points defining the parametric habitat. Thereby the ecological potential of any site within the territory can be established, integrated in a geographical information systems and accordingly charted. The results are compared with those obtained with the methodology traditionally used by Spanish foresters (factorial index), showing that the overall potential area is similar in size but quite different in its distribution.A new approach to the definition of physiographic and climatic potential areas for forest species, based on the ecological field theory, is outlined in this paper. The proposed formulation is tested on the Spanish juniper (Juniperus thurifera L.), using data from 883 permanent and temporary plots throughout its distribution area in the Spanish autonomous region of Castilla y León. The suitability of the territory for the species is assessed by previously studying its habitat, which in turn is analyzed through physiographic and climatic parameters. This new method is rooted in an additive index that depends on the Mahalanobis distance in the parametric space that evaluates the ecological resemblance between the studied site and each of the points defining the parametric habitat. Thereby the ecological potential of any site within the territory can be established, integrated in a geographical information systems and accordingly charted. The results are compared with those obtained with the methodology traditionally used by Spanish foresters (factorial index), showing that the overall potential area is similar in size but quite different in its distribution.

Dynamics of ecosystem services in Pinus sylvestris stands under different managements and site quality classes

Timber and biodiversity are considered two antagonistic ecosystem services (ES), largely influenced by silviculture and site ecological conditions. In order to address the trade-offs between these two ES over time, we performed a retrospective study at compartment level in the Pinus sylvestris forests of the Spanish Central Mountain System. Archival data from Management Plans for eight forests with contrasting silvicultural systems (uniform shelterwood system, group shelterwood system, irregular shelterwood system,) and three different site quality classes were analysed. Timber production was assessed through stand volume, harvested timber volume and a stand volume index. Biodiversity was examined through structural diversity (Gini index, Shannon tree size diversity index, Simpson’s reciprocal index and evenness index, all applied to diameter classes) and the abundance of large living trees. For all silvicultural systems investigated, stand volume and harvested timber volume have grown since the beginning of the management plans (beginning of the twentieth century in some forests). The largest yields of timber corresponded to the best quality sites with more intensive silvicultural treatments (uniform and group shelterwood systems). The uniform shelterwood system showed lower figures for structural diversity, though not always significant. The best site qualities maintained notable structural diversity values, even under the most intensive management system. The application of the different management systems over decades has revealed a synergy between timber production and structural diversity, particularly in those systems maintaining more than one age class, although results are conditioned by forest harvesting history. The interaction between historical silvicultural treatment and site quality has been identified as an important source of information to understand forest dynamics and functioning of ES provision.