Species Mixing Proportion and Aridity Influence in the Height–Diameter Relationship for Different Species Mixtures in Mediterranean Forests

Estimating tree height is essential for modelling and managing both pure and mixed forest stands. Although height–diameter (H–D) relationships have been traditionally fitted for pure stands, attention must be paid when analyzing this relationship behavior in stands composed of more than one species. The present context of global change makes also necessary to analyze how this relationship is influenced by climate conditions. This study tends to cope these gaps, by fitting new H–D models for 13 different Mediterranean species in mixed forest stands under different mixing proportions along an aridity gradient in Spain. Using Spanish National Forest Inventory data, a total of 14 height–diameter equations were initially fitted in order to select the best base models for each pair species-mixture. Then, the best models were expanded including species proportion by area (mi) and the De Martonne Aridity Index (M). A general trend was found for coniferous species, with taller trees for the same diameter size in pure than in mixed stands, being this trend inverse for broadleaved species. Regarding aridity influence on H–D relationships, humid conditions seem to beneficiate tree height for almost all the analyzed species and species mixtures. These results may have a relevant importance for Mediterranean coppice stands, suggesting that introducing conifers in broadleaves forests could enhance height for coppice species. However, this practice only should be carried out in places with a low probability of drought. Models presented in our study can be used to predict height both in different pure and mixed forests at different spatio-temporal scales to take better sustainable management decisions under future climate change scenarios.Forestry, Faculty ofNon UBCForest Resources Management, Department ofReviewedFacultyResearche

Genetic diversity and patterns of population structure in Creole goats from the Americas

Biodiversity studies are more efficient when large numbers of breeds belonging to several countries are involved, as they allow for an in-depth analysis of the within- and between-breed components of genetic diversity. A set of 21 microsatellites was used to investigate the genetic composition of 24 Creole goat breeds (910 animals) from 10 countries to estimate levels of genetic variability, infer population structure and understand genetic relationships among populations across the American continent. Three commercial transboundary breeds were included in the analyses to investigate admixture with Creole goats. Overall, the genetic diversity of Creole populations (mean number of alleles = 5.82 ? 1.14, observed heterozygosity = 0.585 ? 0.074) was moderate and slightly lower than what was detected in other studies with breeds from other regions. The Bayesian clustering analysis without prior information on source populations identified 22 breed clusters. Three groups comprised more than one population, namely from Brazil (Azul and Graúna; Moxotó and Repartida) and Argentina (Long and shorthair Chilluda, Pampeana Colorada and Angora-type goat). Substructure was found in Criolla Paraguaya. When prior information on sample origin was considered, 92% of the individuals were assigned to the source population (threshold q ≥ 0.700). Creole breeds are well-differentiated entities (mean coefficient of genetic differentiation = 0.111 ? 0.048, with the exception of isolated island populations). Dilution from admixture with commercial transboundary breeds appears to be negligible. Significant levels of inbreeding were detected (inbreeding coefficient > 0 in most Creole goat populations, P < 0.05). Our results provide a broad perspective on the extant genetic diversity of Creole goats, however further studies are needed to understand whether the observed geographical patterns of population structure may reflect the mode of goat colonization in the Americas.Estación Experimental Agropecuaria BarilocheFil: Ginja, Catarina. Universidad de Porto; PortugalFil: Gama, Luis T. Universidade de Lisboa. Faculdade de Medicina Veterinaria; PortugalFil: Martinez, Amparo. Universidad de Córdoba. Departamento de Genética; EspañaFil: Sevane Fernandez, Natalia. Universidad Complutense de Madrid. Departamento de Producción Animal; EspañaFil: Martin-Burriel, Inmaculada. Universidad de Zaragoza. Facultad de Veterinaria; EspañaFil: Lanari, María Rosa. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche; ArgentinaFil: Revidatti, María Antonia Susana. Universidad Nacional del Nordeste. Facultad de Ciencias Veterinarias; ArgentinaFil: Aranguren Mendez, Jose Atilio. Universidad de Zulia. Facultad de Ciencias Veterinarias; VenezuelaFil: Bedotti, Daniel Osvaldo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Anguil; ArgentinaFil: Ribeiro, Maria Norma. Universidade Federal Rural de Pernambuco. Departamento de Zootecnia; BrasilFil: Sponenberg, D. Phillip.Virginia Tech. Virginia-Maryland Regional College of Veterinary Medicine; Estados UnidosFil: Aguirre Riofrío, Edgar Lenin. Universidad Nacional de Loja, EcuadorFil: Alvarez Franco, Luz Angela. Universidad Nacional de Colombia; ColombiaFil: Menezes, M.P.C. Universidad Federal de Paraiba; BrasilFil: Chacón Marcheco, Edilberto. Universidad Tecnica de Cotopaxi; EcuadorFil: Galarza, Alexander Josué. Universidad Mayor de San Simón; BoliviaFil: Gómez Urviola, Nilton César. Universidad Nacional Micaela Bastidas de Apurimac; PerúFil: Martinez Lopez, Oscar Roberto. Universidad Nacional de Asunción. Centro Multidisciplinario de Investigaciones Tecnológicas, Dirección General de Investigación Científica y Tecnológica; ParaguayFil: Cavalcanti Pimenta, Edgard. Universidad Federal de Paraiba; BrasilFil: da Rocha, Laura Leandro. Universidade Federal Rural de Pernambuco. Departamento de Zootecnia; BrasilFil: Stemmer, Angelika. Universidad Mayor de San Simón; BoliviaFil: Landi, Vicenzo. Universidad de Córdoba. Departamento de Genética; EspañaFil: Delgado Bermejo, Juan Vicente. Universidad de Córdoba. Departamento de Genética; Españ