Jorge E. Ramírez-Albores

Improved Predictions of the Geographic Distribution of Invasive Plants Using Climatic Niche Models.

Climatic niche models for invasive plants are usually constructed with occurrence records taken from literature and collections. Because these data neither discriminate among life-cycle stages of plants (adult or juvenile) nor the origin of individuals (naturally established or man-planted), the resulting models may mispredict the distribution ranges of these species. We propose that more accurate predictions could be obtained by modelling climatic niches with data of naturally established individuals, particularly with occurrence records of juvenile plants because this would restrict the predictions of models to those sites where climatic conditions allow the recruitment of the species. To test this proposal, we focused on the Peruvian peppertree (Schinus molle), a South American species that has largely invaded Mexico. Three climatic niche models were constructed for this species using high-resolution dataset gathered in the field. The first model included all occurrence records, irrespective of the life-cycle stage or origin of peppertrees (generalized niche model). The second model only included occurrence records of naturally established mature individuals (adult niche model), while the third model was constructed with occurrence records of naturally established juvenile plants (regeneration niche model). When models were compared, the generalized climatic niche model predicted the presence of peppertrees in sites located farther beyond the climatic thresholds that naturally established individuals can tolerate, suggesting that human activities influence the distribution of this invasive species. The adult and regeneration climatic niche models concurred in their predictions about the distribution of peppertrees, suggesting that naturally established adult trees only occur in sites where climatic conditions allow the recruitment of juvenile stages. These results support the proposal that climatic niches of invasive plants should be modelled with data of naturally established individuals because this improves the accuracy of predictions about their distribution ranges.

Predicción de la distribución geográfica y conservación de nicho de un árbol invasor en México

Puerta-Pinero, A. 2016. Identification and evaluation of afforestations through the Spanish National Forest Inventory. Ecosistemas 25(3): 43-50. Doi.: 10.7818/ECOS.2016.25-3.05 Afforestation programs in Spain were performed mainly between 1930-1970 decades. The study of the state and functioning of these anthropogenic forests has a wide debate among scientists and stakeholders. Forest inventories represent a crucial source of data to evaluate the long-term functioning of these forests at broad spatial scales. This article shows several tools to identify and select plots from the third Spanish Forest Inventory composed by uniform afforestations. The functions intend to facilitate the work of scientists and technicians whose objective could be influenced by the presence or absence of these artificial forest type. Those functions are a first attempt to include or exclude plots that are composed by artificially afforested forests. I also present some preliminary results, and discuss strengths, weaknesses and future directions relative to the use of these functions.