Direction Regionale des Eaux et Forets et de la Lutte Contre la Desertification du Rif

Tétouan, Morocco

Direction Regionale des Eaux et Forets et de la Lutte Contre la Desertification du Rif

Tétouan, Morocco

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Soliveres S.,Rey Juan Carlos University | Maestre F.T.,Rey Juan Carlos University | Bowker M.A.,Northern Arizona University | Torices R.,University of Coimbra | And 25 more authors.
Perspectives in Plant Ecology, Evolution and Systematics | Year: 2014

Plant-plant interactions are driven by environmental conditions, evolutionary relationships (ER) and the functional traits of the plants involved. However, studies addressing the relative importance of these drivers are rare, but crucial to improve our predictions of the effects of plant-plant interactions on plant communities and of how they respond to differing environmental conditions. To analyze the relative importance of - and interrelationships among - these factors as drivers of plant-plant interactions, we analyzed perennial plant co-occurrence at 106 dryland plant communities established across rainfall gradients in nine countries. We used structural equation modelling to disentangle the relationships between environmental conditions (aridity and soil fertility), functional traits extracted from the literature, and ER, and to assess their relative importance as drivers of the 929 pairwise plant-plant co-occurrence levels measured. Functional traits, specifically facilitated plants' height and nurse growth form, were of primary importance, and modulated the effect of the environment and ER on plant-plant interactions. Environmental conditions and ER were important mainly for those interactions involving woody and graminoid nurses, respectively. The relative importance of different plant-plant interaction drivers (ER, functional traits, and the environment) varied depending on the region considered, illustrating the difficulty of predicting the outcome of plant-plant interactions at broader spatial scales. In our global-scale study on drylands, plant-plant interactions were more strongly related to functional traits of the species involved than to the environmental variables considered. Thus, moving to a trait-based facilitation/competition approach help to predict that: (1) positive plant-plant interactions are more likely to occur for taller facilitated species in drylands, and (2) plant-plant interactions within woody-dominated ecosystems might be more sensitive to changing environmental conditions than those within grasslands. By providing insights on which species are likely to better perform beneath a given neighbour, our results will also help to succeed in restoration practices involving the use of nurse plants. © 2014 Geobotanisches Institut ETH, Stiftung Ruebel.


Delgado-Baquerizo M.,Pablo De Olavide University | Maestre F.T.,Rey Juan Carlos University | Gallardo A.,Pablo De Olavide University | Quero J.L.,Rey Juan Carlos University | And 11 more authors.
PLoS ONE | Year: 2013

While much is known about the factors that control each component of the terrestrial nitrogen (N) cycle, it is less clear how these factors affect total N availability, the sum of organic and inorganic forms potentially available to microorganisms and plants. This is particularly true for N-poor ecosystems such as drylands, which are highly sensitive to climate change and desertification processes that can lead to the loss of soil nutrients such as N. We evaluated how different climatic, abiotic, plant and nutrient related factors correlate with N availability in semiarid Stipa tenacissima grasslands along a broad aridity gradient from Spain to Tunisia. Aridity had the strongest relationship with N availability, suggesting the importance of abiotic controls on the N cycle in drylands. Aridity appeared to modulate the effects of pH, plant cover and organic C (OC) on N availability. Our results suggest that N transformation rates, which are largely driven by variations in soil moisture, are not the direct drivers of N availability in the studied grasslands. Rather, the strong relationship between aridity and N availability could be driven by indirect effects that operate over long time scales (decades to millennia), including both biotic (e.g. plant cover) and abiotic (e.g. soil OC and pH). If these factors are in fact more important than short-term effects of precipitation on N transformation rates, then we might expect to observe a lagged decrease in N availability in response to increasing aridity. Nevertheless, our results suggest that the increase in aridity predicted with ongoing climate change will reduce N availability in the Mediterranean basin, impacting plant nutrient uptake and net primary production in semiarid grasslands throughout this region. © 2013 Delgado-Baquerizo et al.


Rojo L.,Ministerio de Agricultura Alimentacion y Medio Ambiente | Bautista S.,University of Alicante | Orr B.J.,University of Arizona | Cortina J.,University of Alicante | Derak M.,Direction Regionale des Eaux et Forets et de la Lutte Contre la Desertification du Rif
Science et Changements Planetaires - Secheresse | Year: 2012

Prevention and restoration actions to combat desertification: an integrated assessment (PRACTICE) is a support action of the European Commission Seventh Framework Programme for Research and Technological Development, which is being developed during three years since September 2009. It gathers scientists and stakeholders from several desertification affected regions of the world, in order to learn from ongoing experiences on combating desertification, such as afforestation, improving pastures, controlled grazing, watershed management, and sustainable agricultural practices. The central goal of PRACTICE is to link science to society in order to share and transfer evaluation methods and practices to combat desertification. To pursue this goal, PRACTICE first aims to develop and implement an integrated evaluation protocol to assess the effectiveness of prevention and restoration practices, applicable worldwide. The evaluation protocol of PRACTICE considers the mutual interactions between human and environment. The assessment protocol also represents an integrated approach because it considers simultaneously both, biophysical and socioeconomic attributes. The protocol is based on (1) key common indicators that represent overall ecosystem and human-environmental system functioning, (2) sitespecific indicators identified by local stakeholders that are relevant to the objectives and the particular context conditions, and (3) stakeholder perspectives. Indicators are selected in the framework of ecosystem services developed by the Millennium Ecosystem Assessment (MEA), focusing on human well-being and trying to be consistent with the desertification impact indicators selected by the United Nations Convention to Combat Desertification (UNCCD) and with recommendations by Convention on Biological Biodiversity (CBD) and United Nations Framework Convention on Climate Change (UNFCCC). Multi-criteria decision models will be used for integrating the information provided by the various biophysical and socioeconomic indicators and for integrating the stakeholder perspectives. This paper presents the status of the project in June 2011 on the occasion of the seminar. "Policies, programmes and projects to combat desertification. How to evaluate them?".


Ulrich W.,Nicolaus Copernicus University | Soliveres S.,Rey Juan Carlos University | Soliveres S.,University of Bern | Maestre F.T.,Rey Juan Carlos University | And 50 more authors.
Journal of Biogeography | Year: 2014

Aim: Geographical, climatic and soil factors are major drivers of plant beta diversity, but their importance for dryland plant communities is poorly known. The aim of this study was to: (1) characterize patterns of beta diversity in global drylands; (2) detect common environmental drivers of beta diversity; and (3) test for thresholds in environmental conditions driving potential shifts in plant species composition. Location: Global. Methods: Beta diversity was quantified in 224 dryland plant communities from 22 geographical regions on all continents except Antarctica using four complementary measures: the percentage of singletons (species occurring at only one site); Whittaker's beta diversity, β(W); a directional beta diversity metric based on the correlation in species occurrences among spatially contiguous sites, β(R2); and a multivariate abundance-based metric, β(MV). We used linear modelling to quantify the relationships between these metrics of beta diversity and geographical, climatic and soil variables. Results: Soil fertility and variability in temperature and rainfall, and to a lesser extent latitude, were the most important environmental predictors of beta diversity. Metrics related to species identity [percentage of singletons and β(W)] were most sensitive to soil fertility, whereas those metrics related to environmental gradients and abundance [(β(R2) and β(MV)] were more associated with climate variability. Interactions among soil variables, climatic factors and plant cover were not important determinants of beta diversity. Sites receiving less than 178 mm of annual rainfall differed sharply in species composition from more mesic sites (> 200 mm). Main conclusions: Soil fertility and variability in temperature and rainfall are the most important environmental predictors of variation in plant beta diversity in global drylands. Our results suggest that those sites annually receiving c. 178 mm of rainfall will be especially sensitive to future climate changes. These findings may help to define appropriate conservation strategies for mitigating effects of climate change on dryland vegetation. © 2014 John Wiley & Sons Ltd.


PubMed | University of New South Wales, Rey Juan Carlos University, Technical University of Loja, University of Coimbra and 8 more.
Type: Journal Article | Journal: Perspectives in plant ecology, evolution and systematics | Year: 2015

Plant-plant interactions are driven by environmental conditions, evolutionary relationships (ER) and the functional traits of the plants involved. However, studies addressing the relative importance of these drivers are rare, but crucial to improve our predictions of the effects of plant-plant interactions on plant communities and of how they respond to differing environmental conditions. To analyze the relative importance of -and interrelationships among- these factors as drivers of plant-plant interactions, we analyzed perennial plant co-occurrence at 106 dryland plant communities established across rainfall gradients in nine countries. We used structural equation modeling to disentangle the relationships between environmental conditions (aridity and soil fertility), functional traits extracted from the literature, and ER, and to assess their relative importance as drivers of the 929 pairwise plant-plant co-occurrence levels measured. Functional traits, specifically facilitated plants height and nurse growth form, were of primary importance, and modulated the effect of the environment and ER on plant-plant interactions. Environmental conditions and ER were important mainly for those interactions involving woody and graminoid nurses, respectively. The relative importance of different plant-plant interaction drivers (ER, functional traits, and the environment) varied depending on the region considered, illustrating the difficulty of predicting the outcome of plant-plant interactions at broader spatial scales. In our global-scale study on drylands, plant-plant interactions were more strongly related to functional traits of the species involved than to the environmental variables considered. Thus, moving to a trait-based facilitation/competition approach help to predict that: 1) positive plant-plant interactions are more likely to occur for taller facilitated species in drylands, and 2) plant-plant interactions within woody-dominated ecosystems might be more sensitive to changing environmental conditions than those within grasslands. By providing insights on which species are likely to better perform beneath a given neighbour, our results will also help to succeed in restoration practices involving the use of nurse plants.


PubMed | Ferdowsi University of Mashhad, University of Sfax, Direction Regionale des Eaux et Forets et de la Lutte Contre la Desertification du Rif, Technical University of Loja and 24 more.
Type: Journal Article | Journal: Journal of biogeography | Year: 2015

Geographic, climatic, and soil factors are major drivers of plant beta diversity, but their importance for dryland plant communities is poorly known. This study aims to: i) characterize patterns of beta diversity in global drylands, ii) detect common environmental drivers of beta diversity, and iii) test for thresholds in environmental conditions driving potential shifts in plant species composition.224 sites in diverse dryland plant communities from 22 geographical regions in six continents.Beta diversity was quantified with four complementary measures: the percentage of singletons (species occurring at only one site), Whittakes beta diversity ((W)), a directional beta diversity metric based on the correlation in species occurrences among spatially contiguous sites ((RSoil fertility and variability in temperature and rainfall, and to a lesser extent latitude, were the most important environmental predictors of beta diversity. Metrics related to species identity (percentage of singletons and (W)) were most sensitive to soil fertility, whereas those metrics related to environmental gradients and abundance (((RSoil fertility and variability in temperature and rainfall are the most important environmental predictors of variation in plant beta diversity in global drylands. Our results suggest that those sites annually receiving ~ 178 mm of rainfall will be especially sensitive to future climate changes. These findings may help to define appropriate conservation strategies for mitigating effects of climate change on dryland vegetation.

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