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Nieto O.M.,University of Granada | Castro J.,Ifapa Centro Camino Of Purchil Junta Of Andalucia | Fernandez-Ondono E.,University of Granada
Plant and Soil | Year: 2013

Background and Aims: For croplands, controversy persists concerning the adequacy of the soil use and the management of environmental problems such as soil erosion and fertility in a context of climate change. In this study, we used the RothC model to evaluate the capacity of carbon fixation by the soil in a Mediterranean olive grove for two different scenarios: the land-use change from native vegetation (NV) to conventional tillage (T) in the olive grove, and for the change in soil management from conventional tillage to cover crop (CC). Methods: In three experimental olive groves in Andalusia (S Spain) two soil-management systems were sampled: T and CC. Areas of NV adjacent to the grove were also sampled as indicative of the initial state of the soil without olive trees. We measured the aboveground biomass production of the cover and the clay content, bulk density, and soil organic carbon (SOC) for 0-5, 5-15 and 15-30 cm depth. Results: The removal of NV to implement T resulted in a significantly loss of SOC that depended mainly on the relief of the terrain. However, the use of CC increased the SOC because of greater inputs (above-and belowground plant inputs) to the soil. The final concentration at each location was related to the carbon inputs and the clay content. The CC resulted in carbon storage during the first year of 4. 02 ± 1. 65 Mg C ha-1, and a total carbon fixation by the soil of 5. 91 ± 2. 06 Mg C ha-1. Conclusion: The use of cover crops in Mediterranean olive groves proved to be a suitable strategy to increase the carbon storage into the soil and then to decrease the CO2 concentration in the atmosphere. © 2012 Springer Science+Business Media B.V.


Fernandez-Ondono E.,University of Granada | Serrano L.R.,Direccion General de Medio Natural y Politica Forestal | Jimenez M.N.,University of Granada | Navarro F.B.,Ifapa Centro Camino Of Purchil Junta Of Andalucia | And 6 more authors.
European Journal of Forest Research | Year: 2010

In the 20th century, in the Mediterranean area, many extensive afforestation efforts were made with the primary objective of protecting soils from erosion and improving their fertility. This study evaluates the effects of the afforestation undertaken in the Guadalentín basin (SE Spain) with respect to the organic and inorganic soil constituents and physico-chemical soil properties. Given the phytoclimatic environments in the basin (sclerophyllous and hyperxerophyllous), paired samples were taken beneath the tree canopy of the pine plantations and in nearby open zones. With the same methodology, samples were taken from areas considered to be native forest. The data were submitted to different multivariate analyses of variance (two-way MANOVAs) in order to compare the effects and interactions of the factors CANOPY (with and without trees), PHYTOCLIMATE (sclerophyllous and hyperxerophyllous), and TYPE OF FOREST (afforested or native) on the dependent variables measured (soil variables). Significant differences were found at 0-10 cm in soil depth under pine afforestations in relation to adjacent open areas. Below this depth, differences were found only between phytoclimatic environments. No significant interactions were found between the variables analysed at any of the depths, indicating that the effects of the afforestations on the soil characteristics were independent of the phytoclimatic environment. The afforestation in the Guadalentín basin, in the two phytoclimatic environments considered increased the soil fertility. Nevertheless, the native forests presented the highest soil organic-carbon contents, mainly in the sclerophyllous phytoclimate type (Quercus ilex subsp. ballota forests). Therefore, although the afforestations improved the soil fertility in relation to the open areas, the maximum potential has probably not been reached in relation to that observed in the native forests. The effects that forest development (age, basal area) over time exerts on soil properties remain to be verified by further research. © 2010 Springer-Verlag.


Jimenez M.N.,Ifapa Centro Camino Of Purchil Junta Of Andalucia | Spotswood E.N.,University of California at Berkeley | Canadas E.M.,University of Cagliari | Navarro F.B.,Ifapa Centro Camino Of Purchil Junta Of Andalucia
Applied Vegetation Science | Year: 2015

Questions: How do thinning and understorey management practices (ploughing, clearing) to reduce fire risk affect plant species composition, diversity and biomass within pine plantations on previous croplands? Do managed pine plantations promote changes in plant succession compared to unplanted areas (old fields) towards restoration goals including holm oak forest or other alternative land-use types? Location: Altiplano del Conejo, Guadix-Baza Basin, SE Iberian Peninsula, Spain. Methods: We evaluated plant species composition, diversity, cover and biomass in the understorey of a semi-arid 10-yr-old afforestation area of Pinus halepensis through a manipulative experiment in which four different thinning regimes (T0 treatment: control plots; T100, T75, T60 and T48 treatments: 100%, 75%, 60%, and 48% of mean basal area removed, respectively), and two understorey vegetation treatments (clearing, ploughing) were applied, simulating stand practices to reduce fire risk. Sampling was performed annually for 5 yr (from 2006 to 2010). For comparison, four other land-use types (rain-fed cereal crops, old fields, alpha grass steppes and holm oak forests) were sampled to quantify understorey vegetation community composition and diversity. Results: Afforestation plots were compositionally distinct from each other within 5 yr, mainly as a result of canopy thinning and to a lesser extent, vegetation treatments. Total species richness was highest in the low to medium densities of pines, where richness approached that found in native communities. However, afforestation plots were most similar in diversity, life-form type and composition to abandoned agricultural fields, and large differences were found between afforestation plots, native forests and alpha grass steppes. Conclusions: This study demonstrates that plant species composition in the understorey of pine plantations on former cropland can respond rapidly to common management practices intended to reduce fire risk. In particular, tree thinning increases both understorey plant diversity and biomass, but does not lead to recruitment of species that are typical of native forests. Rates of native forest succession appear to be slow in this semi-arid Mediterranean ecosystem. Current pine plantation management practices, while useful for increasing understorey biomass and plant diversity will need to be coupled with additional restoration techniques (e.g. seeding and transplants) to recover species composition and structure of native forests. This paper shows how restoration thinning and vegetation treatments (clearing and ploughing) used to reduce fire risk can modify the understorey vegetation in pine plantations on previous croplands, increasing plant diversity and/or biomass. However, it does not lead to recruitment of species that are typical of the native forests, and stand management should be coupled with active restoration techniques. © 2014 International Association for Vegetation Science.


Canadas E.M.,University of Granada | Jimenez M.N.,Ifapa Centro Camino Of Purchil Junta Of Andalucia | Valle F.,University of Granada | Fernandez-Ondono E.,University of Granada | And 2 more authors.
Journal of Arid Environments | Year: 2010

In recent decades a large proportion of agricultural lands have been abandoned in European countries, mainly in semi-arid or mountain Mediterranean areas. Environmental processes in old fields have attracted the attention of many scientists, but several issues remain unanswered. This study seeks to identify the edaphic factors determining changes in perennial-plant communities in old fields of a Mediterranean semi-arid area (Baza Basin, SE Spain) and elucidate the main relationships between these communities. For this goal, we mapped all old fields in this study area and calculated the surface area occupied by each community (single and mixed). Floristic data and soil samples were collected for all the communities, through a stratified sampling, and the data were subjected to several statistical treatments (ANOVA, DCA, CCA, Spearman correlation). The joint study of floristic and edaphic variables confirmed that the soil determines mainly the establishment of vegetation in old fields of this area. Specifically, salinity, moisture, and gravel content accounted for most of the floristic variation. The results may be useful for old-field management, for example, to identify areas that should not be cultivated due to salinity or to the high ecological value. © 2010 Elsevier Ltd.

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