Comparing the Sexual Reproductive Success of Two Exotic Trees Invading Spanish Riparian Forests vs. a Native Reference

A widely accepted hypothesis in invasion ecology is that invasive species have higher survival through the early stages of establishment than do non-invasive species. In this study we explore the hypothesis that the sexual reproductive success of the invasive trees Ailanthus altissima (Mill.) Swingle and Robinia pseudoacacia L. is higher than that of the native Fraxinus angustifolia Vahl., all three species coexisting within the riparian forests of Central Spain. We compared different stages of the early life cycle, namely seed rain, seed infestation by insects, seed removal by local fauna, seed germination under optimal conditions and seedling abundance between the two invasive trees and the native, in order to assess their sexual reproductive success. The exotic species did not differ from the native reference (all three species displaying high seed rain and undergoing seed losses up to 50% due to seed removal by the local fauna). Even if the exotic R. pseudoacacia showed a high percentage of empty and insect-parasited seeds along with a low seedling emergence and the exotic A. altissima was the species with more viable seeds and of higher germinability, no differences were found regarding these variables when comparing them with the native F. angustifolia. Unsuitable conditions might have hampered either seedling emergence and survival, as seedling abundance in the field was lower than expected in all species -especially in R. pseudoacacia-. Our results rather suggest that the sexual reproductive success was not higher in the exotic trees than in the native reference, but studies focusing on long-term recruitment would help to shed light on this issue

The “outer dimensions”: impulsivity, anger/aggressiveness, activation

The “outer” SVARAD dimensions, impulsivity, anger/aggressiveness, and activation, represent trans-diagnostic psychological and behavioural domains that span traditional categorical boundaries. At the neurobiological level, the fronto-limbic and the fronto-cerebellar circuitry, as well as molecular pathways involving dopamine, serotonin, testosterone, and inflammatory mediators, play a crucial role in mediating the biological underpinnings of these psychopathological dimensions. From a clinical perspective, as the combination of clusters of symptoms differs from patient to patient and gives rise to a wide variety of clinical pictures even among subjects with the same diagnosis, it is important that the clinical features related to impulsivity, anger, aggressiveness, and activation are specifically and multiparametrically investigated and treated. The aim of the present chapter is to discuss the psychopathological aspects, the neurobiological underpinnings, and the clinical implications related to the “outer dimensions” in clinical psychiatry