Self-thinning in four pine species: an evaluation of potential climate impacts

Brunet-Navarro, P., Sterck, F.J., Vayreda, J., Martinez-Vilalta, J., Mohren, G.M.J. (2016) Self-thinning in four pine species: an evaluation of potential climate impacts. Annals of Forest Science. 73: 1025-1034.
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Doi: 10.1007/s13595-016-0585-y

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Positive biodiversity-productivity relationship predominant in global forests

Liang, J., Crowther, T.W., Picard, N., Wiser, S., Zhou, M., Alberti, G., Schulze, E.-D., McGuire, A.D., Bozzato, F., Pretzsch, H., De-Miguel, S., Paquette, A., Hérault, B., Scherer-Lorenzen, M., Barrett, C.B., Glick, H.B., Hengeveld, G.M., Nabuurs, G.-J., Pfautsch, S., Viana, H., Vibrans, A.C., Ammer, C., Schall, P., Verbyla, D., Tchebakova, N., Fischer, M., Watson, J.V., Chen, H.Y.H., Lei, X., Schelhaas, M.-J., Lu, H., Gianelle, D., Parfenova, E.I., Salas, C., Lee, E., Lee, B., Kim, H.S., Bruelheide, H., Coomes, D.A., Piotto, D., Sunderland, T., Schmid, B., Gourlet-Fleury, S., Sonké, B., Tavani, R., Zhu, J., Brandl, S., Vayreda, J., Kitahara, F., Searle, E.B., Neldner, V.J., Ngugi, M.R., Baraloto, C., Frizzera, L., Bałazy, R., Oleksyn, J., Zawiła-Niedźwiecki, T., Bouriaud, O., Bussotti, F., Finér, L., Jaroszewicz, B., Jucker, T., Valladares, F., Jagodzinski, A.M., Peri, P.L., Gonmadje, C., Marthy, W., O'Brien, T., Martin, E.H., Marshall, A.R., Rovero, F., Bitariho, R., Niklaus, P.A., Alvarez-Loayza, P., Chamuya, N., Valencia, R., Mortier, F., Wortel, V., Engone-Obiang, N.L., Ferreira, L.V., Odeke, D.E., Vasquez, R.M., Lewis, S.L., Reich, P.B. (2016) Positive biodiversity-productivity relationship predominant in global forests. Science. 354: 0-0.
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Doi: 10.1126/science.aaf8957

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Anthropogenic-driven rapid shifts in tree distribution lead to increased dominance of broadleaf species

Vayreda, J., Martinez-Vilalta, J., Gracia, M., Canadell, J.G., Retana, J. (2016) Anthropogenic-driven rapid shifts in tree distribution lead to increased dominance of broadleaf species. Global Change Biology. 22: 3984-3995.
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Doi: 10.1111/gcb.13394

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The Ecological Forest Inventory of Catalonia: A tool for functional ecology [El Inventario Ecológico y Forestal de Cataluña: una herramienta para la ecología funcional]

Vayreda, J., Martínez-Vilalta, J., Vilà-Cabrera, A. (2016) The Ecological Forest Inventory of Catalonia: A tool for functional ecology [El Inventario Ecológico y Forestal de Cataluña: una herramienta para la ecología funcional]. Ecosistemas. 25: 70-79.
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Doi: 10.7818/ECOS.2016.25-3.08

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Large-scale recruitment limitation in Mediterranean pines: The role of Quercus ilex and forest successional advance as key regional drivers

Carnicer J., Coll M., Pons X., Ninyerola M., Vayreda J., Penuelas J. (2014) Large-scale recruitment limitation in Mediterranean pines: The role of Quercus ilex and forest successional advance as key regional drivers. Global Ecology and Biogeography. 23: 371-384.
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Doi: 10.1111/geb.12111

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Aim: Large-scale patterns of limitations in tree recruitment remain poorly described in the Mediterranean Basin, and this information is required to assess the impacts of global warming on forests. Here, we unveil the existence of opposite trends of recruitment limitation between the dominant genera Quercus and Pinus on a large scale and identify the key ecological drivers of these diverging trends. Location: Spain Methods: We gathered data from the Spanish National Forest inventory to assess recruitment trends for the dominant species (Pinus halepensis, Pinus pinea, Pinus pinaster, Pinus nigra, Pinus sylvestris, Pinus uncinata, Quercus suber, Quercus ilex, Quercus petraea, Quercus robur, Quercus faginea and Quercus pyrenaica). We assessed the direct and indirect drivers of recruitment by applying Bayesian structural equation modelling techniques. Results: Severe limitations in recruitment were observed across extensive areas for all Pinus species studied, with recruitment failure affecting 54-71% of the surveyed plots. In striking contrast, Quercus species expanded into 41% of the plots surveyed compared to only 10% for Pinus and had a lower local recruitment failure (29% of Quercus localities compared to 63% for Pinus species). Bayesian structural equation models highlighted the key role of the presence of Q.ilex saplings and the increase in the basal area of Q.ilex in limiting recruitment in five Pinus species. The recruitment of P.sylvestris and P.nigra showed the most negative trends and was negatively associated with the impacts of fire. Main conclusions: This study identified Q.ilex, the most widespread species in this area, as a key driver of recruitment shifts on a large scale, negatively affecting most pine species with the advance of forest succession. These results highlight that the future expansion/contraction of Q.ilex stands with ongoing climate change will be a key process indirectly controlling the demographic responses of Pinus species in the Mediterranean Basin. © 2013 John Wiley & Sons Ltd.

Llegeix més

SMOS and climate data applicability for analyzing forest decline and forest fires

Chaparro D., Vayreda J., Martinez-Vilalta J., Vall-Llossera M., Banque M., Camps A., Piles M. (2014) SMOS and climate data applicability for analyzing forest decline and forest fires. International Geoscience and Remote Sensing Symposium (IGARSS). : 1069-1072.
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Doi: 10.1109/IGARSS.2014.6946613

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Forests partially reduce climate change impact but, at the same time, this climate forcing threatens forest's health. In recent decades, droughts are becoming more frequent and intense implying an increase of forest decline episodes and forest fires. In this context, global and frequent soil moisture observations from the ESA's SMOS mission could be useful in controlling forest exposure to decline and fires. In this paper, SMOS observations and several climate variables are analyzed together with decline and fire inventories, to study the effect of soil moisture on forest decline during an important drought on summer 2012, and on forest fires in the period 2010-2013. Results show that SMOS-derived soil moisture is a complementary variable in forest decline models. Some of the studied tree species exhibit high probability of decline occurrence under dry conditions. First results showed burned areas to be drier than unburned ones previous to the fire occurrences. © 2014 IEEE.

Llegeix més

Soil carbon stocks and their variability across the forests, shrublands and grasslands of peninsular Spain

Doblas-Miranda E., Rovira P., Brotons L., Martinez-Vilalta J., Retana J., Pla M., Vayreda J. (2013) Soil carbon stocks and their variability across the forests, shrublands and grasslands of peninsular Spain. Biogeosciences. 10: 8353-8361.
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Doi: 10.5194/bg-10-8353-2013

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Accurate estimates of C stocks and fluxes of soil organic carbon (SOC) are needed to assess the impact of climate and land use change on soil C uptake and soil C emissions to the atmosphere. Here, we present an assessment of SOC stocks in forests, shrublands and grasslands of peninsular Spain based on field measurements in more than 900 soil profiles. SOC to a depth of 1 m was modelled as a function of vegetation cover, mean annual temperature, total annual precipitation, elevation and the interaction between temperature and elevation, while latitude and longitude were used to model the correlation structure of the errors. The resulting statistical model was used to estimate SOC in the ∼8 million pixels of the Spanish Forest Map (29.3 × 106 ha). We present what we believe is the most reliable estimation of current SOC in forests, shrublands and grasslands of peninsular Spain thus far, based on the use of spatial modelling, the high number of profiles and the validity and refinement of the data layers employed. Mean concentration of SOC was 8.7 kg m-2, ranging from 2.3 kg m-2 in dry Mediterranean areas to 20.4 kg m -2 in wetter northern locations. This value corresponds to a total stock of 2.544 Tg SOC, which is four times the amount of C estimated to be stored in the biomass of Spanish forests. Climate and vegetation cover were the main variables influencing SOC, with important ecological implications for peninsular Spanish ecosystems in the face of global change. The fact that SOC was positively related to annual precipitation and negatively related to mean annual temperature suggests that future climate change predictions of increased temperature and reduced precipitation may strongly reduce the potential of Spanish soils as C sinks. However, this may be mediated by changes in vegetation cover (e.g. by favouring the development of forests associated to higher SOC values) and exacerbated by perturbations such as fire. The estimations presented here provide a baseline to estimate future changes in soil C stocks and to assess their vulnerability to key global change drivers, and should inform future actions aimed at the conservation and management of C stocks. © 2013 Author(s).

Llegeix més

Patterns and drivers of regeneration of tree species in forests of peninsular Spain

Vayreda J., Gracia M., Martinez-Vilalta J., Retana J. (2013) Patterns and drivers of regeneration of tree species in forests of peninsular Spain. Journal of Biogeography. 40: 1252-1265.
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Doi: 10.1111/jbi.12105

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Aim: Our study aimed to identify and explore the main factors that influence tree recruitment of multiple species at a regional scale across peninsular Spain, an understanding of which is essential for predicting future forest species composition in the face of ongoing environmental change. The study focused on the dynamics of the key transition phase from saplings to adult trees. Location: The forests of peninsular Spain. Methods: We used the extensive network of plots sampled in two consecutive Spanish national forest inventories (> 30,000 plots) to identify the factors that determine regeneration patterns of the 10 most abundant forest species of Spain at relatively large temporal (c. 10 years) and spatial scales (across Spain): five coniferous species of Pinus (pines) and five broadleaved species of the genera Fagus and Quercus. We fitted separate generalized linear models for the pine species and the broadleaved species to assess the response of sapling abundance and ingrowth rate to the spatial variability of climate (temperature, water availability and recent warming), forest structure (tree density, understorey and overstorey canopy cover, and basal area change) and disturbances (previous forest logging, wildfires and grazing). Results: Mean sapling abundance was four times higher for broadleaved species than for pines, while mean annual ingrowth was twice as high. Sapling abundance and ingrowth rate were mainly determined by stand structure, both in pines and broadleaved trees. The direct effects of disturbances and climate were comparatively smaller, and there was no detectable effect of recent warming. Main conclusions: The higher values of ingrowth rate of broadleaved species can be explained by their ability to maintain a higher sapling bank due to their greater shade tolerance. This differential response of pines and broadleaved species to canopy closure suggests a probable increase in broadleaved species at the expense of pines. This transition could occur earlier in stands with faster canopy closure dynamics. Spatially explicit, mixed-species demographic models incorporating both the ingrowth and the tree mortality components are needed for predicting the composition of future forests. © 2013 Blackwell Publishing Ltd.

Llegeix més

Disentangling Biodiversity and Climatic Determinants of Wood Production

Vilà M., Carrillo-Gavilán A., Vayreda J., Bugmann H., Fridman J., Grodzki W., Haase J., Kunstler G., Schelhaas M.J., Trasobares A. (2013) Disentangling Biodiversity and Climatic Determinants of Wood Production. PLoS ONE. 8: 0-0.
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Doi: 10.1371/journal.pone.0053530

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Background: Despite empirical support for an increase in ecosystem productivity with species diversity in synthetic systems, there is ample evidence that this relationship is dependent on environmental characteristics, especially in structurally more complex natural systems. Empirical support for this relationship in forests is urgently needed, as these ecosystems play an important role in carbon sequestration. Methodology/Principal Findings: We tested whether tree wood production is positively related to tree species richness while controlling for climatic factors, by analyzing 55265 forest inventory plots in 11 forest types across five European countries. On average, wood production was 24% higher in mixed than in monospecific forests. Taken alone, wood production was enhanced with increasing tree species richness in almost all forest types. In some forests, wood production was also greater with increasing numbers of tree types. Structural Equation Modeling indicated that the increase in wood production with tree species richness was largely mediated by a positive association between stand basal area and tree species richness. Mean annual temperature and mean annual precipitation affected wood production and species richness directly. However, the direction and magnitude of the influence of climatic variables on wood production and species richness was not consistent, and vary dependent on forest type. Conclusions: Our analysis is the first to find a local scale positive relationship between tree species richness and tree wood production occurring across a continent. Our results strongly support incorporating the role of biodiversity in management and policy plans for forest carbon sequestration. © 2013 Vilà et al.

Llegeix més

Patterns of fuel types and crown fire potential in Pinus halepensis forests in the Western Mediterranean Basin

Alvarez A., Gracia M., Vayreda J., Retana J. (2012) Patterns of fuel types and crown fire potential in Pinus halepensis forests in the Western Mediterranean Basin. Forest Ecology and Management. 270: 282-290.
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Doi: 10.1016/j.foreco.2011.01.039

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Using the databases from the Spanish Forest Inventories, we have classified the forest structures of Pinus halepensis plots across the Iberian Peninsula into different fuel types as a function of the most common fire types that can be supported. The purposes of this study are to determine (i) the proportion of the different fuel types and fire type associated with different disturbance scenarios (undisturbed, after a recent wildfire, after an old wildfire and after thinning), (ii) the effect of climate and soil type on the distribution of fuel types and (iii) the effect of the different disturbance scenarios on the transitions between these fuel types. After a recent wildfire the risk of spreading active crown fires was reduced but the risk increased with time since last fire and in undisturbed areas. Climate and stoniness influenced the spatial distribution of fuel types and the potential crown fire risk. There was a lower risk of active crown fires when there was higher aridity and higher stoniness. Disturbances modify the transitions between fuel types; after a wildfire there was the highest change in fuel types with an increase of fuel type one with open forest structures and the presence of plots without trees that are linked to lower risk of active crown fires. There was also a reduction of fuel types 3 and 4, which burn with high intensity during a wildfire. In the absence of disturbances or after an old wildfire, changes between fuel types were slow, usually leading to increasing canopy closure and higher risk of active crown fires. After thinning there were also important changes in fuel types, with a reduction of active crown fire risk after thinning from below and heavy thinning. Fire plays an important role in maintaining landscape heterogeneity. As a consequence of climate warming, new areas with high structural continuity will increase the risk of extreme fire behavior, and for this reason, small wildfires and specific thinning treatments are the key to reduce crown fire potential. © 2011 Elsevier B.V.

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