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Lines E.R.,University of Cambridge | Zavala M.A.,CIFOR INIA | Zavala M.A.,University of Alcalá | Purves D.W.,Microsoft | Coomes D.A.,University of Cambridge
Global Ecology and Biogeography | Year: 2012

Aim Trees are often observed to get shorter and more narrowly crowned in dry regions and at high elevations. We explore how this pattern is driven by two opposing factors: competition for light makes it advantageous to extend branches to their biomechanical limit, whereas under cold or arid conditions it is advantageous to have shorter branches, thereby reducing the length of the hydraulic transport system and embolism risk. Using data from 700,000 trees of 26 species, we quantify how environmental conditions influence the scaling of height and crown diameter (CD) with stem diameter (d.b.h.). We compare our predictions with those of metabolic scaling theory (MST), which suggests that allometry is invariant of environment. Location 48,000 inventory plots that systematically sample mainland Spain, a region in which climate varies strongly. Methods We fit d.b.h.-height and d.b.h.-CD functions using Bayesian methods, allowing comparison of within- and across-species trends in allometry along gradients of temperature, precipitation, drought and competition for light (i.e. the basal area of taller trees). Results The competitive environment had a strong influence on aboveground allometry, but all trees were far shorter than predicted by biomechanical models, suggesting that factors other than biomechanics are important. Species that dominate in arid and cold habitats were much shorter (for a given diameter) than those from benign conditions; but within-species heights did not vary strongly across climatic gradients. Main conclusions Our results do not support the MST prediction that d.b.h.-height and d.b.h.-CD allometries are invariant, or that biomechanical constraints determine height allometry. Rather, we highlight the role of hydraulic limitations in this region. The fact that intra-specific adjustment in d.b.h.-CD - height allometry along environmental gradients was far weaker than across-species changes may indicate genetic constraints on allometry which might contribute to niche differentiation among species. © 2012 Blackwell Publishing Ltd.

Perez-Ramos I.M.,IRNAS | Urbieta I.R.,University of Castilla - La Mancha | Zavala M.A.,CIFOR INIA | Zavala M.A.,University of Alcalá | Maranon T.,IRNAS
Journal of Ecology | Year: 2012

In heterogeneous environments, species segregate spatially in response to selective abiotic and biotic filters occurring throughout plant ontogeny. Ontogenetic conflicts in recruitment may lead to spatially discordant patterns of regeneration among microhabitats with different plant cover. In addition, species differing in seed size may be subjected to opposing ecological and evolutionary pressures throughout the life cycle of the plant. We used a multi-stage demographic approach aimed at characterizing the main stage-specific probabilities of recruitment (seed survival, seed germination, seedling emergence and survival during the first 3years of life) in two Mediterranean oak species coexisting at southern Spain. We calibrated linear and nonlinear likelihood models for each of these consecutive life history stages and calculated overall probabilities of recruitment along a wide range of plant cover and seed size variation. Seed predation and seedling mortality over the dry season were the most limiting processes for the two studied oak species. However, species ranking diverged substantially through the life history stages considered in this study due to different ontogenetic trends among species. At the intraspecific level, recruitment-driving processes during the seed and the seedling stages showed opposing tendencies along the explored range of plant cover and seed size. Thus, small-sized acorns and open areas were favoured for the seed stage, whereas large acorns and dense microhabitats did for the seedling stage. The existence of opposing selective pressures on seed mass and their differential influence on the two studied oak species determined the occurrence of species-specific optimal seed sizes (small acorns for Quercus canariensis vs. acorns of large or intermediate size for Quercus suber). The spatial patterns predicted by our overall-recruitment models provided some evidence of regeneration niche partitioning in the two coexisting oak species, supporting their current distribution patterns as saplings and adults at the study area. Synthesis. We conclude that within- and among-species differences through plant ontogeny, arising from species differential response to microhabitat heterogeneity and seed size variation, could be of great importance for oak species niche segregation, driving stand dynamics and spatial pattern distribution along the landscape. The information provided by this study could be also applied to optimize management and restoration programmes since it has enabled us to identify the most favourable conditions and traits for recruitment in oak species that exhibit serious constraints for natural regeneration. © 2011 The Authors. Journal of Ecology © 2011 British Ecological Society.

Ruiz-Benito P.,CIFOR INIA | Ruiz-Benito P.,University of Alcalá | Gomez-Aparicio L.,CIFOR INIA | Gomez-Aparicio L.,CSIC - Institute of Natural Resources and Agriculture Biology of Seville | And 2 more authors.
Diversity and Distributions | Year: 2012

Aim There is increasing concern regarding sustainable management and restoration of planted forests, particularly in the Mediterranean Basin where pine species have been widely used. The aim of this study was to analyse the environmental and structural characteristics of Mediterranean planted pine forests in relation to natural pine forests. Specifically, we assessed recruitment and woody species richness along climatic, structural and perturbation gradients to aid in developing restoration guidelines. Location Continental Spain. Methods We conducted a multivariate comparison of ecological characteristics in planted and natural stands of main Iberian native pine species (Pinus halepensis, Pinus pinea, Pinus pinaster, Pinus nigra and Pinus sylvestris). We fitted species-specific statistical models of recruitment and woody species richness and analysed the response of natural and planted stands along ecological gradients. Results Planted pine forests occurred on average on poorer soils and experienced higher anthropic disturbance rates (fire frequency and anthropic mortality) than natural pine forests. Planted pine forests had lower regeneration and diversity levels than natural pine forests, and these differences were more pronounced in mountain pine stands. The largest differences in recruitment - chiefly oak seedling abundance - and species richness between planted and natural stands occurred at low-medium values of annual precipitation, stand tree density, distance to Quercus forests and fire frequency, whereas differences usually disappeared in the upper part of the gradients. Main conclusions Structural characteristics and patterns of recruitment and species richness differ in pine planted forests compared to natural pine ecosystems in the Mediterranean, especially for mountain pines. However, management options exist that would reduce differences between these forest types, where restoration towards more natural conditions is feasible. To increase recruitment and diversity, vertical and horizontal heterogeneity could be promoted by thinning in high-density and homogeneous stands, while enrichment planting would be desirable in mesic and medium-density planted forests. © 2012 Blackwell Publishing Ltd.

Benito Garzon M.,CIFOR INIA | Benito Garzon M.,University Paris - Sud | Alia R.,CIFOR INIA | Robson T.M.,CIFOR INIA | And 3 more authors.
Global Ecology and Biogeography | Year: 2011

Aim To assess the effect of local adaptation and phenotypic plasticity on the potential distribution of species under future climate changes. Trees may be adapted to specific climatic conditions; however, species range predictions have classically been assessed by species distribution models (SDMs) that do not account for intra-specific genetic variability and phenotypic plasticity, because SDMs rely on the assumption that species respond homogeneously to climate change across their range, i.e. a species is equally adapted throughout its range, and all species are equally plastic. These assumptions could cause SDMs to exaggerate or underestimate species at risk under future climate change. Location The Iberian Peninsula. Methods Species distributions are predicted by integrating experimental data and modelling techniques. We incorporate plasticity and local adaptation into a SDM by calibrating models of tree survivorship with adaptive traits in provenance trials. Phenotypic plasticity was incorporated by calibrating our model with a climatic index that provides a measure of the differences between sites and provenances. Results We present a new modelling approach that is easy to implement and makes use of existing tree provenance trials to predict species distribution models under global warming. Our results indicate that the incorporation of intra-population genetic diversity and phenotypic plasticity in SDMs significantly altered their outcome. In comparing species range predictions, the decrease in area occupancy under global warming conditions is smaller when considering our survival-adaptation model than that predicted by a 'classical SDM' calibrated with presence-absence data. These differences in survivorship are due to both local adaptation and plasticity. Differences due to the use of experimental data in the model calibration are also expressed in our results: we incorporate a null model that uses survival data from all provenances together. This model always predicts less reduction in area occupancy for both species than the SDM calibrated with presence-absence. Main conclusions We reaffirm the importance of considering adaptive traits when predicting species distributions and avoiding the use of occurrence data as a predictive variable. In light of these recommendations, we advise that existing predictions of future species distributions and their component populations must be reconsidered. © 2011 Blackwell Publishing Ltd.

Benito-Garzon M.,CIFOR INIA | Benito-Garzon M.,French National Center for Scientific Research | Ruiz-Benito P.,CIFOR INIA | Ruiz-Benito P.,University of Alcalá | And 2 more authors.
Global Ecology and Biogeography | Year: 2013

Aim: Tree growth may be enhanced by carbon dioxide fertilization unless drought stress becomes too severe, yet the likely increase in tree growth under a warmer climate is still controversial. Tree mortality has increased in some regions, but its multifactorial nature makes the prediction of likely global trends difficult. The aims of this work are: (1) to assess which abiotic, structural and competition factors influence tree growth and tree mortality in mainland Spain, and (2) to evaluate whether these processes would drive species distributions and would improve current niche model predictions. Location: Continental Spain. Methods: We projected species distributional models by integrating nonparametric tree growth and tree mortality models based on repeated surveys of diameter at breast height and mortality for 40,721 trees distributed in 45,301 plots, which include the 11 most common canopy tree species in continental Spain, as measured in the second and third National Forest Inventories, with a mean lag time of 11 years. Results: Tree growth and tree mortality were explained by an assemblage of many factors, among which climate and competition played a key role. The accuracy of models including tree growth and tree mortality in predicting tree habitat suitability was comparable to classical niche models based on species occurrence. Projections under climate change showed for 9 out of 11 species, a likely increase in tree growth that would be counteracted by an increase in tree mortality, suggesting that even if growth rates increase, mortality would limit the species ranges under global warming expectations. Main conclusions: Growth and mortality are major determinants of species distributions. Under future climate change expectations, our model suggests that growth may increase for some Iberian species, but even in this case, species ranges at the rear edge would be limited by an increase in mortality rates. © 2013 John Wiley & Sons Ltd.

Gea-Izquierdo G.,Swiss Federal Institute of forest | Cherubini P.,Swiss Federal Institute of forest | Canellas I.,CIFOR INIA
Forest Ecology and Management | Year: 2011

We analyzed tree rings over the past 100 years to understand the response of Quercus ilex L. to climate change at four different sites along a temperature gradient in a highly anthropogenically transformed ecosystem. To test the hypothesis of a climate change related decrease in productivity at warmer sites, we discuss the effect of historical management on the growth of forest stands and the spatio-temporal variability of growth in response to climate, analyzing departures from linearity in that relationship. We reconstructed stand history and investigated past growth trends using tree-rings. Then we used a dendroecological approach to study the regional, local and age-dependent response to climate, analyzing the relationship between precipitation and tree growth using non-linear mixed models. Tree rings reflected the origin of the studied landscape, mainly a simplification of an original closed forest and progressive canopy opening for agrosilvopastoral purposes after the mid 1800s. As expected, trees were principally responding to water availability, and regional growth (as expressed by the first principal component from the matrix of chronologies) was highly responsive to hydrological year precipitation (r=0.7). In this water limited ecosystem, the response of growth to precipitation was asymptotic and independent of age, but variable in time. Maximum growth was variable at the different sites and the non-linear function of growth saturated (i.e. reached an asymptote) at temperature dependent site specific precipitation levels within the range considered in the region to lead a shift towards deciduous species dominated woodlands (around 600. mm, variable with mean temperature). Only trees at warmer sites showed symptoms of growth decline, most likely explained by water stress increase in the last decades affecting the highly transformed open (i.e. low competition) tree structure. Stands at colder locations did not show any negative growth trend and may benefit from the current increase in winter temperatures. Coinciding with the decrease in productivity, trees at warmer sites responded more to moisture availability, exhibited a slower response to precipitation and reached maximum growth at higher precipitation levels than trees at colder sites. This suggests that warmer stands are threatened by climate change. The non-linear response of growth to precipitation described is meaningful for different ecological applications and provides new insights in the way trees respond to climate. © 2011 Elsevier B.V.

Ledo A.,Technical University of Madrid | Burslem D.F.R.P.,University of Aberdeen | Condes S.,Technical University of Madrid | Montes F.,CIFOR INIA
Journal of Vegetation Science | Year: 2013

Questions: Species-habitat associations may contribute to the maintenance of species richness in tropical forests, but previous research has been conducted almost exclusively in lowland forests and has emphasized the importance of topography and edaphic conditions. Is the distribution of woody plant species in a Peruvian cloud forest determined by microhabitat conditions? What is the role of environmental characteristics and forest structure in habitat partitioning in a tropical cloud forest? Location: Cloud Forest, north Peruvian Andes. Methods: We examined species-habitat associations in three 1-ha plots using the torus-translation method. We used three different criteria to define habitats for habitat partitioning analyses, based on microtopography, forest structure and both sets of factors. The number of species associated either positively or negatively with each habitat was assessed. Results: Habitats defined on the basis of environmental conditions and forest structure discriminated a greater number of positive and negative associations at the scale of our analyses in a tropical cloud forest. Conclusions: Both topographic conditions and forest structure contribute to small-scale microhabitat partitioning of woody plant species in a Peruvian tropical cloud forest. Nevertheless, canopy species were most correlated with the distribution of environmental variables, while understorey species displayed associations with forest structure. © 2012 International Association for Vegetation Science.

Journal of Tropical Forest Science | Year: 2015

Inventorying field mapped plots can be difficult in tropical forest because visibility and access are limited due to high density of woody plants. Additionally, steep slopes and frequent presence of fog further complicate field measurements in mountain areas. The objective of this study was to propose a detailed field census protocol. The method described allowed inventory of mapped 1-ha plots in a montane cloud forest with little cost and time. The inventory also included the recording of some environmental conditions, namely, light, soil coverage temperature and humidity. A detailed explanation dealing with species identification in the forest is also included. The method can be extended to different tropical as well as temperate forest ecosystems. Finally, a summary and comparison with different inventories focusing on mapped trees are given, along with a number of recommendations. © Forest Research Institute Malaysia.

Hernandez-Serrano A.,CIDE CSIC | Verdu M.,CIDE CSIC | Gonzalez-Martinez S.C.,CIFOR INIA | Pausas J.G.,CIDE CSIC
American Journal of Botany | Year: 2013

Premise of the study: Serotiny (delayed seed release with the consequent accumulation of a canopy seedbank) confers fitness benefits in environments with crown-fire regimes. Thus, we predicted that serotiny level should be higher in populations recurrently subjected to crown-fires than in populations where crown-fires are rare. In addition, under a high frequency of fires, space and resources are recurrently available, permitting recruitment around each mother to follow the seed rain shadow. Thus, we also predicted spatial aggregation of serotiny within populations. Methods: We compared serotiny, considering both the proportion and the age of serotinous cones, in populations living in contrasting fire regimes for two iconic Mediterranean pine species (Pinus halepensis, P. pinaster). We framed our results by quantitatively comparing the strength of the fire-serotiny relationship with previous studies worldwide. •Key results: For the two species, populations living under high crown-fire recurrence regimes had a higher serotiny level than those populations where the recurrence of crown-fires was low. For P. halepensis (the species with higher serotiny), populations in high fire recurrence regimes had higher fine-scale spatial aggregation of serotiny than those inhabiting low fire recurrence systems. The strength of the observed fire-serotiny relationship in P. halepensis is among the highest in published literature. Conclusions: Fire regime shapes serotiny level among populations, and in populations with high serotiny, recurrent fires maintain a significant spatial structure for this trait. Consequently, fire has long-term evolutionary implications at different scales, emphasizing its prominent role in shaping the ecology of pines. © 2013 Botanical Society of America.

Carbonell G.,Laboratory for Ecotoxicology | Imperial R.M.D.,Laboratory of Depuration and Agricultural Use of Animal Manure and Urban Waste | Torrijos M.,Laboratory for Ecotoxicology | Delgado M.,Laboratory of Depuration and Agricultural Use of Animal Manure and Urban Waste | Rodriguez J.A.,CIFOR INIA
Chemosphere | Year: 2011

Soil amendments based on crop nutrient requirements are considered a beneficial management practice. A greenhouse experiment with maize seeds (Zea mays L.) was conducted to assess the inputs of metals to agricultural land from soil amendments. Maize seeds were exposed to a municipal solid waste (MSW) compost (50Mgha-1) and NPK fertilizer (33g plant-1) amendments considering N plant requirement until the harvesting stage with the following objectives: (1) determine the accumulation of total and available metals in soil and (2) know the uptake and ability of translocation of metals from roots to different plant parts, and their effect on biomass production. The results showed that MSW compost increased Cu, Pb and Zn in soil, while NPK fertilizer increased Cd and Ni, but decreased Hg concentration in soil. The root system acted as a barrier for Cr, Ni, Pb and Hg, so metal uptake and translocation were lower in aerial plant parts. Biomass production was significantly enhanced in both MSW and NPK fertilizer-amended soils (17%), but also provoked slight increases of metals and their bioavailability in soil. The highest metal concentrations were observed in roots, but there were no significant differences between plants growing in amended soil and the control soil. Important differences were found for aerial plant parts as regards metal accumulation, whereas metal levels in grains were negligible in all the treatments. © 2011 Elsevier Ltd.

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