Geographic variation in growth, survival, and susceptibility to the processionary moth (Thaumetopoea pityocampa Dennis & Schiff.) of Pinus halepensis Mill. and P. brutia Ten.: results from common gardens in Morocco

International audienceAbstractKey messageAdaptation ofPinus brutiaandPinus halepensisto harsh Moroccan environments varied considerably among populations, with variation following marked geographic clines.ContextMediterranean pines are drought tolerant species that play relevant ecological and economic roles in North Africa. Mediterranean pines harbor huge intraspecific variation in adaptive traits.AimsExploring the relative performance of different seed sources and analyzing the genotype by environment (G × E) interaction becomes, thus, essential for maximizing the efficiency of any reforestation program.MethodsWe present the results of a comprehensive quantitative analysis of growth, survival, and resistance to the processionary moth of 57 populations of P. halepensis Mill. and P. brutia Ten. tested under severe drought conditions in two contrasting Moroccan test sites differing in water regime, soil, and physiographic conditions.ResultsThe results indicated the existence of considerable variation between species and among populations within species in growth, survival, and susceptibility to the processionary moth (Thaumetopoea pityocampa Dennis & Schiff.), but low plasticity across sites, despite the apparently large environmental differences between them. On average, P. brutia performed better than P. halepensis. The G × E interaction was significant for all traits and ages, but an in-depth analysis revealed that the main source of the interaction was due to large differences in residual variances across sites, while the relative population ranks remained highly consistent across sites.ConclusionGrowth and survival of Aleppo pine populations followed well-defined geographical clines, with populations from the Eastern range of the distribution, particularly those of Greece, showing outstanding performance. The two local Aleppo pine populations were, however, also among the best-growing and surviving populations. Superiority of Eastern Aleppo pine populations was not considered high enough to recommend their use in reforestation programs. Aiming to preserve local genetic resources, local seed sources are preferred for reforestation in the dry areas of Morocco. Planting middle to high elevation Turkish populations of the non-native P. brutia is also an alternative, especially in more mesic sites. The reduced G × E suggests that the above recommendations may be valid, even in the context of future climate change

Timing of resin-tapping operations in maritime pine forests in Northern Spain

Aim of study: To optimize the timing of resin-tapping activities for maximizing the economic efficiency of resin tapping in Atlantic maritime pine forests. Area of study: Northern Spain. Material and methods: We conducted three small experiments in a mature maritime pine forest aimed to test: i) the impact of groove frequency on resin production, ii) the effect of previous grooves as a driver of temporal patterns of resin production along the seasons and iii) the impact of previous tapping on resin production in the following campaign. Main results: The resin produced decreased as groove frequency decreased, but the reduction was low. Considering that the number of trees that a worker can tap increases with more spaced grooves, higher tapping efficiency can be achieved with monthly grooves. Previous tapping increased resin yield during the following campaign but resin production was not affected by the previous grooves during the current tapping campaign. Research highlights: Responses to wounding seem to require time to be effective and temporal patterns of resin production appear to be driven by weather conditions alone. Keywords: resin yield; Pinus pinaster; seasonality; induced responses; wounding

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

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

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

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