Plasticidad fenotípica de Pinus pinaster frente a la disponibilidad de nutrientes

7 páginas, 4 figuras, 1 tabla -- Comunicación presentada en la IV Reunión sobre Genética Forestal (2008), celebrada en Pontevedra entre el 27 y el 29 de junio de 2007.En tres ensayos factoriales familia x fertilización situados en sitios de baja fertilidad en el Sur de Galicia se analizó la plasticidad fenotípica en el desarrollo y la variación genética en plasticidad en familias de medios hermanos de Pinus pinaster. La autocorrelación espacial que presentaron las variables de estudio invalidaron las técnicas de análisis convencional, siendo necesario ajustar los datos espacialmente mediante técnicas de geoestadística. En las tres parcelas se encontró variación genética en el crecimiento de la población de estudio además de plasticidad fenotípica frente a la disponibilidad de nutrientes en el gradiente de fertilización ensayado. En concordancia con estudios nutricionales previos en Galicia, la fertilización resultó ser beneficiosa para el crecimiento de las plantas. También se encontró variación genética en la plasticidad en todas las parcelas, lo que indica que existen variaciones genéticas en la eficacia nutricional entre las familias estudiadas. Sin embargo, la interacción fertilización x sitio, familia x sitio y familia x fertilización x sitio muestra un patrón de respuesta complejo.Este trabajo se ha realizado al amparo del Proyecto de Investigación INIA-RTA05-173.Peer reviewe

Spatial structure of deciduous forest stands with contrasting human influence in northwest Spain

Five contrasting deciduous forest stands were studied to characterize the spatial structural variability in human-influenced forests. These stands are representative of cultural forest types widely represented in western Europe: one plantation, two coppices, one wood-pasture forest and one high forest stand. All stems with DBH > 5 cm were measured and mapped, and stem DBH distributions, spatial structure of DBH, spatial point patterns and spatial associations were analysed. Spatial autocorrelation for DBH was calculated with Moran’s I correlograms and semivariograms. Complete spatial randomness hypothesis for spatial point patterns, and both independence and random labelling hypotheses for spatial associations were analysed using Ripley’s K function. The results showed that tree sizes were conditioned by particular former management systems, which determined unimodal symmetric, positively skewed or compound DBH distributions. Spatial structure was more complex when human influence became reduced. Coppice stands showed clumped spatial patterns and independence among size classes, as a consequence of sexual and vegetative establishment of new stems in open areas. The largest clumping intensity was observed in the wood-pasture with an intermediate disturbance frequency and low inter-tree competition. The high forest stand displayed spatial traits consistent with the gap-dynamics paradigm, such as clumping of smaller trees, random arrangement of larger trees, negative association between juveniles and adults, and high structural heterogeneity. It can be expected that after cessation of human interference, coppices and wood-pastures would evolve to a more heterogeneous structure, probably with a higher habitat and species diversity.This research was partially supported by the Consejería de Medio Ambiente del Principado de Asturias (SV-PA-00-01).Peer reviewe

Genetic variation and phenotypic plasticity of nutrient re-allocation and increased fine root production as putative tolerance mechanisms inducible by methyl jasmonate in pine trees

1. Plant plastic responses to herbivore damage may include rapid, active reallocation of plant resources to reduce the impact of herbivory on future plant fitness. However, whether these inducible tolerance responses can be extended to pine trees and how these responses could be modulated by genetic and environmental factors remains unclear.2. Biomass allocation and phosphorus (P) and nitrogen (N) concentrations in above- and belowground tissues were measured in Pinus pinaster juveniles belonging to 33 open-pollinated families grown under two P availabilities (P-deficient and complete fertilization). Measurements were taken 15 days after half of the plants received a foliar spray treatment of 22 mmol L)1 methyl jasmonate (MJ) to simulate above-ground herbivore attack.3. Simulated above-ground herbivory promoted a strong preferential allocation of biomass below ground in the form of fine roots, leading to an almost two-fold increase in fine root biomass in MJ-treated plants and a significant reduction in above-ground tissues and coarse roots. In addition, MJ signalling increased P andN concentrations in the shoots while reducing (P) or maintaining (N) concentrations in the roots. These results suggest that induced resource sequestration is not a generalized strategy in this pine species. Fine root biomass and concentration of N and P in plant tissues showed additive genetic variation, but responses to MJ signalling did not vary among families. Allocation of biomass to fine roots was not affected by P availability, whereas allocation of P to the shoot was more intense under complete fertilization.4. Synthesis: Two new putative tolerance mechanisms inducible by MJ signalling may help to minimize the impact of above-ground herbivore damage on the future fitness of young pine trees by (i) allocation of carbon to fine roots, this appeared to be a generalized strategy with weak environmental modulation and (ii) reallocation of P and N from roots to shoots, which was largely affected by P availability, and thus susceptible to greater phenotypic variation in heterogeneous environments. We provide evidence that changes in tolerance-related traits are rapidly inducible by herbivory cues in this pine species. These results should be integrated with induced resistance responses to fully understand the costs and benefits associated with induced responses to herbivory.This research was supported by the grants AGL2010-18724, RTA07-100, PSE310000. LS and XM received financial support from DOC-INIA and PREDOC-INIA grant programs respectively.INIAPeer Reviewe

Phenotypic plasticity of maritime pine to insect herbivory

PósterPeer Reviewe

Stability across sites of Douglas-fir provenances in northern Spain

This study examines the stability across sites for height growth at different ages in a multi-site Douglas-fir provenance test in Northern Spain in order to study its implications for provenance use recommendations and breeding strategies. A total of 89 IUFRO provenances, planted on 16 sites, were analysed. Type B correlations were used to examine the relation among geographical differences between sites and their site-to-site correlations. The site index differences between sites was the only variable that explained the Type B correlation variation, indicating that P x E interaction arises from site index differences between test sites. The lack of significant correlations between geographical differences and Type B correlations between sites, suggested that all the studied area should be considered as a unique breeding zone. Despite the relative high Type B correlation within all the studied area (r, > 0.6), the analyses of variance indicated a high relative importance of the P x E interaction, especially at the earlier stages. This interaction must be considered for selection and provenances recommendation. It was concluded that selection should be made for stability and overall good performance within the whole area. Provenance stability over the site index variation was analysed by the joint regression analysis. Significant stability differences were found among provenances. Considering both the overall performance and the stability, 11 provenances were recommended for Northern Spain. Most of these provenances come from North Oregon and South Washington, from latitudes north of 45 " N.This study was financed, during the last years, by the European Projects EUDIREC CT95-0909 and FEDER lFD97-0585-C-03-01.UEPeer reviewe

Nutritional status and genetic variation in the response to nutrient availability in Pinus pinaster. A multisite field study in NW Spain

The low nutrient availability of the acidic and sandy soils of Galicia (Northwest Spain) is probably the main environmental factor limiting forest primary productivity in the area. These particular edaphic conditions could have imposed selective pressures on maritime pine populations leading to specific local adaptations. We first assessed the nutritional status of 22 young contemporary Pinus pinaster plantations in Northwest Spain, and then analysed the response to fertilization in three family × fertilization trials, and how this response varied across sites and genotypes. Growth of P. pinaster in Northwest Spain appeared to be largely limited by nutrient availability, where most of the plantations showed severe nutrient deficiencies, especially in P and Mg. According to these deficiencies, a strong positive response to nutrient additions was observed in the three trials, with height increments of up to 30% compared with the unfertilized control. However, the response to fertilizers was very variable from site to site, and in some cases did not agree with the foliar nutritional diagnosis. The response to fertilization was also significantly affected by pine genotype, suggesting that the plastic response to nutrient additions within each environment was under genetic control. However, the family response to nutrient availability was not consistent across sites, and no significant differences among families were observed for the RDPI plasticity index – a single index that summarizes the phenotypic change in multiple environments – when analysed across environments. The strong environmental component modulating phenotypic responses to fertilization could impose an important obstacle to evolve specific adaptations to the local edaphic conditions, as well as to artificially select genotypes adapted to different environments and silviculture regimes.This research was funded by the INIA projects RTA05-173 and RTA07-100.Peer reviewe

Genetics, phosphorus availability, and herbivore-derived induction as sources of phenotypic variation of leaf volatile terpenes in a pine species

Oleoresin produced and stored in pine tree leaves provides direct resistance to herbivores, while leaf volatile terpenes (LVT) in the resin are also powerful airborne infochemicals. Resin concentration and profile show considerable spatial and temporal phenotypic variation within and among pine populations. LVT biochemistry is known to be under genetic control, and although LVT should be plastic to diverse abiotic and biotic environmental factors such as nutrient availability and herbivore attack, little is known about their relative contributions and interactive effects. The aim of this paper was to clarify whether reduced phosphorus availability could increase the LVT concentration and affect the expression of herbivore-derived induced defences, and how plasticity would contribute to the phenotypic variation of LVT. The constitutive and methyl-jasmonate (MeJa) induced LVT concentration and profile were analysed in 17 half-sib Pinus pinaster families growing under two levels of P-availability (complete and P-limited fertilization). Individual terpene concentrations showed large additive genetic variation, which was more pronounced in the control than in MeJa-induced pines. MeJa application did not affect the LVT concentration, but significantly modified the LVT profile by depleting the α-pinene content and reducing the sesquiterpene fraction. Low P-availability strongly reduced plant growth and foliar nutrient concentrations, but did not affect LVT concentration and profile, and did not interact with MeJa-induction. Results indicate a strong homeostasis of LVT concentration to P-availability, and minor changes in the LVT profile due to MeJa-induction. Genetic variation appears to be the main source of phenotypic variation affecting the LVT concentration in this pine species.This work was supported by the Spanish Instituto Nacional de Investigación y Tecnología Agraria y Agroalimentaria (grant number INIA-RTA07-100; and DOC-INIA and PREDOC-INIA fellows for LS and XM, respectively); the Spanish Agency of Science and Technology (grant numbers CGL2006-04025/BOS, CGL2010-17172, and CSD2008- 00040 for JP and JL; and AGL2010-18724 and PSE310000 for RZ and LS); and the Catalonian Government (grant number SGR 2009-1458).Peer reviewe

Densidad y área de los canales resiníferos de "Pinus pinaster" ante tratamientos de fertilización, y su relación con la defensa ante "Hylobius abietis"

6 páginas, 3 tablas -- Actas de la I Reunión sobre Sanidad Forestal celebrada en Palencia el 24 y 25 de septiembre de 2007.Las coníferas poseen una estructura de canales resiníferos que actúa como defensa contra el ataque de insectos y patógenos. Varios autores han observado que un aumento en la disponibilidad de nutrientes puede alterar el reparto de energía en las plantas, en detrimento de los sistemas defensivos. El presente estudio tiene como objetivo determinar el efecto de la fertilización de establecimiento sobre el desarrollo del sistema de canales resiníferos en Pinus pinaster. Mediante histología en brinzales de 3 savias sometidos a dos ensayos familia x fertilización se cuantificó la densidad y el área de los canales resiníferos del floema y del xilema tanto en el tallo principal como en ramas laterales en dos ensayos familia x fertilización. Se observó un efecto significativo de la fertilización en el desarrollo de los canales resiníferos del floema (p<0,05), con valores de 0,45 y 0,36 canales.mm-2 para brinzales no fertilizados y sí fertilizados, respectivamente. Este efecto no se observó en las variables del xilema. La densidad de canales resiníferos en el xilema fue significativamente diferente entre las dos parcelas estudiadas, siendo mayor en la atacada por el curculiónido Hylobius abietis. Por último, la relación tallo-rama de las variables cuantificadas no fue lo suficientemente consistente como para utilizar los canales en ramas de P. pinaster como indicadores de los canales en el tronco principal.Este trabajo se ha realizado bajo financiación del proyecto INIA-RTA05-173.Peer reviewe

Consequences of spatial heterogeneity in the analysis and design of experiments

Las variables analizadas en los estudios ecológicos de campo muestran con frecuencia estructuras espaciales no aleatorias que pueden condicionar los resultados de las técnicas de análisis de la estadística convencional. Aunque la aplicación de diseños experimentales más o menos complejos mejora la eficiencia estadística de los análisis, en muchas ocasiones estos diseños no se pueden acoplar suficientemente bien al patrón espacial real de las variables objeto de estudio, siendo necesario la aplicación de técnicas más depuradas de análisis espacial para un correcto análisis de los datos. En este artículo se discuten los efectos que la autocorrelación espacial de los datos tiene sobre su análisis mediante técnicas de estadística paramétrica y se propone un método de ajuste espacial, basado en técnicas de geoestadística, para analizar datos espacialmente autocorrelacionados. A su vez se presenta un caso concreto real donde se puede observar como el análisis convencional de datos espacialmente autocorrelacionados puede generar conclusiones totalmente erróneas.Many traits assessed in field ecological trials show nonrandom spatial structures that may affect the efficiency of standard statistical analyses. Although several more or less sophisticated experimental designs may improve this efficiency by controlling the spatial variation, there are many situations where designs can not be properly arranged to actual spatial patterns. In such cases, spatial analysis techniques become essential to correctly analyse spatial autocorrelated data. In this paper, the effects of spatial autocorrelation on the results of conventional statistical analysis are discussed, and a spatial adjustment procedure, based on geostatistics, is proposed to be used when data are spatially autocorrelated. A case study is presented to show how conventional analysis of spatially autocorrelated data may give completely erroneous conclusions.Este trabajo ha sido financiado por los proyectos INIA-RTA2-109 e INIA-RTA5-173

Foliar nutrient status and nutritional relationships of young Pinus radiata D. Don plantations in northwest Spain

Fifty-four plots of young Pinus radiata D. Don plantations on abandoned agricultural land in Galicia (northwest Spain) were selected for nutritional diagnosis. Nutritional status was assessed by foliar analysis using the critical levels method. The relationships between foliar nutrient concentrations and the plantation’s growth and survival and the topsoil physical and chemical properties were also analyzed. The most common deficiencies among plots were P and Mg. Foliar N concentrations were relatively high and generally they were above the critical level. Foliar N:P, N:K and N:Mg ratios were significantly unbalanced in 31, 44 and 17 out of 54 studied plots. Foliar P levels were significantly higher on sites with previous herbaceous land use and on soils with a finer texture, whereas foliar Mg levels were higher at low altitudes. Foliar nutrient levels were not significantly correlated with their respective soil levels except in the case of K. Foliar Ca and Mg concentrations correlated positively with topsoil pH. Growth correlated positively with foliar K and Mg concentrations and negatively with foliar N:P, N:K and N:Mg ratios. Percentage of dead and poor state plants were negatively correlated with foliar P, K and Ca levels and positively correlated with foliar N:P and N:Mg ratios. These results suggested that nitrogen may be in excess and may condition the uptake of other nutrients. Foliar N level was considered as an unfavorable parameter, whereas foliar P, K, Ca and Mg concentrations were considered as favorable parameters for P. radiata establishment in Galicia.This study was financed by the Spanish DGCYT (Project FO-032) and carried out in the Lourizán Forest Research Center, Pontevedra.Peer reviewe