Multiscale assessment of woody species recruitment in Mediterranean shrublands: facilitation and beyond

Forest recovery in Mediterranean environments is influenced by factors such as aridity, herbivory and facilitation by shrubs, as well as by seed limitation in the case of highly fragmented forests. How these various factors interact can determine the direction of secondary succession, yet these interactions are poorly understood. We assessed the relative importance of several factors in forest species recruitment in Retama sphaerocarpa (L.) Boiss (Retama) shrublands at different spatial scales.Ministerio de Economía y CompetitividadComunidad de Madri

Direct and indirect effects of climate on demography and early growth of Pinus sylvestris at the rear edge: changing roles of biotic and abiotic factors

Global change triggers shifts in forest composition, with warming and aridification being particularly threatening for the populations located at the rear edge of the species distributions. This is the case of Scots pine (Pinus sylvestris) in the Mediterranean Basin where uncertainties in relation to its dynamics under these changing scenarios are still high. We analysed the relative effect of climate on the recruitment patterns of Scots pine and its interactions with local biotic and abiotic variables at different spatial scales. Number of seedlings and saplings was surveyed, and their annual shoot growth measured in 96 plots located across altitudinal gradients in three different regions in the Iberian Peninsula. We found a significant influence of climate on demography and performance of recruits, with a non-linear effect of temperature on the presence of juveniles, and a positive effect of precipitation on their survival. Abundance of juveniles of P. sylvestris that underwent their first summer drought was skewed towards higher altitudes than the altitudinal mean range of the conspecific adults and the optimum elevation for seedlings¿ emergence. At local level, light availability did not influence juveniles¿ density, but it enhanced their growth. Biotic interactions were found between juveniles and the herb cover (competition) and between the number of newly emerged seedlings and shrubs (facilitation). Results also highlighted the indirect effect that climate exerts over the local factors, modulating the interactions with the pre-existing vegetation that were more evident at more stressful sites. This multiscale approach improves our understanding of the dynamics of these marginal populations and some management criteria can be inferred to boost their conservation under the current global warming.Funding was provided by the Spanish Ministry for Innovation and Science with the grant Consolider-Montes (CSD2008_00040), and the European Union with the projects BACCARA (CE: FP7-226299, 7FP) and FunDivEUROPE (CE: FP7-ENV-2010. 265171).Peer Reviewe

Conservation strategies for endangered arable plant Euphorbia gaditana

Fragmentation and habitat loss are considered among the most important threats to biodiversity. More precisely, transformation of natural habitats into farmlands has been identified as one of the primary causes of plant species extinction. Therefore, understanding the effects of habitat fragmentation is crucial to the successful conservation of threatened species. Metapopulation modeling is one of the prospective tools used in conservation biology to evaluate long-term survival in fragmented landscapes. In this work, we applied a metapopulation approach to the conservation of the rare plant Euphorbia gaditana Coss., an endangered species growing on the margins of crops in southern Spain. The species is threatened due to herbicide application and intensification of cultivation, which results in a highly patchy distribution, with more than 50 patches of habitat across three separate networks of patches. We used IFM (Incidence Function Modeling) to compare the relative effectiveness of four conservation management scenarios and the effect of three threat scenarios on the risk of extinction of the species. The results of our simulations of population dynamics under plausible management scenarios will aid conservation decision-making, for example, allowing priority conservation areas to be identified or assessing the effect of future reintroductions

Canagliflozin and renal outcomes in type 2 diabetes and nephropathy

BACKGROUND Type 2 diabetes mellitus is the leading cause of kidney failure worldwide, but few effective long-term treatments are available. In cardiovascular trials of inhibitors of sodium–glucose cotransporter 2 (SGLT2), exploratory results have suggested that such drugs may improve renal outcomes in patients with type 2 diabetes. METHODS In this double-blind, randomized trial, we assigned patients with type 2 diabetes and albuminuric chronic kidney disease to receive canagliflozin, an oral SGLT2 inhibitor, at a dose of 100 mg daily or placebo. All the patients had an estimated glomerular filtration rate (GFR) of 30 to <90 ml per minute per 1.73 m2 of body-surface area and albuminuria (ratio of albumin [mg] to creatinine [g], >300 to 5000) and were treated with renin–angiotensin system blockade. The primary outcome was a composite of end-stage kidney disease (dialysis, transplantation, or a sustained estimated GFR of <15 ml per minute per 1.73 m2), a doubling of the serum creatinine level, or death from renal or cardiovascular causes. Prespecified secondary outcomes were tested hierarchically. RESULTS The trial was stopped early after a planned interim analysis on the recommendation of the data and safety monitoring committee. At that time, 4401 patients had undergone randomization, with a median follow-up of 2.62 years. The relative risk of the primary outcome was 30% lower in the canagliflozin group than in the placebo group, with event rates of 43.2 and 61.2 per 1000 patient-years, respectively (hazard ratio, 0.70; 95% confidence interval [CI], 0.59 to 0.82; P=0.00001). The relative risk of the renal-specific composite of end-stage kidney disease, a doubling of the creatinine level, or death from renal causes was lower by 34% (hazard ratio, 0.66; 95% CI, 0.53 to 0.81; P<0.001), and the relative risk of end-stage kidney disease was lower by 32% (hazard ratio, 0.68; 95% CI, 0.54 to 0.86; P=0.002). The canagliflozin group also had a lower risk of cardiovascular death, myocardial infarction, or stroke (hazard ratio, 0.80; 95% CI, 0.67 to 0.95; P=0.01) and hospitalization for heart failure (hazard ratio, 0.61; 95% CI, 0.47 to 0.80; P<0.001). There were no significant differences in rates of amputation or fracture. CONCLUSIONS In patients with type 2 diabetes and kidney disease, the risk of kidney failure and cardiovascular events was lower in the canagliflozin group than in the placebo group at a median follow-up of 2.62 years

Sistema de cruzamiento del arbusto Colutea hispanica (Leguminosae)

Plant breeding systems have been viewed as mechanisms to promote outcrossing in order to increase genetic variability and prevent inbreeding depression. However, reduced fitness after crossing, outbreeding depression, has been often observed between individuals from different populations and more rarely, within populations. We studied the breeding system of Colutea hispanica using experimental hand pollinations in field conditions in one population in Central Spain in 2004 and 2006. Pollination experiments showed that C. hispanica set fruits from both self and cross-pollinations, suggesting that the species is highly self-compatible. In addition, fruit set was highest following geitonogamy in both years and no flowers set fruits from xenogamy in 2004. Although such enhanced reproductive success following selfing rather than crossing has been largely ignored in many studies on plant reproduction, it seems to be not as rare in plants as previously thought.Los sistemas reproductivos en las plantas se han considerado como mecanismos que promueven los cruzamientos con la finalidad de aumentar la variabilidad genética y evitar la endogamia. Sin embargo se ha observado con frecuencia un reducido éxito reproductor tras cruzamientos entre individuos de diferentes poblaciones, lo que se ha denominado “depresión exogámica” e incluso más raramente entre individuos de la misma población. Se estudió el sistema de cruzamiento de Colutea hispanica mediante la aplicación de polinizaciones manuales en el campo en una población situada en Madrid (España) durante los años 2004 y 2006. Se obtuvieron frutos tanto por autopolinización como por polinización cruzada, sugiriendo que la especie posee un sistema altamente compatible. La alta autocompatibilidad observada podría deberse a una adaptación a condiciones de escasez de polinizadores y de “parejas reproductoras”. El máximo valor de fruit set se alcanzó en los cruzamientos geitonogámicos en ambos años, y en el año 2004 los cruzamientos xenógamos no produjeron ningún fruto. Este último fenómeno parece ser más común entre plantas de lo que en principio se podría pensar, pero ha sido ignorado en la mayor parte de los estudios de biología reproductora

Breeding system of the iberian endemic shrub "Colutea hispanica" (Leguminosae)

Plant breeding systems have been viewed as mechanisms to promote outcrossing in order to increase genetic variability and prevent inbreeding depression. However, reduced fitness after crossing, outbreeding depression, has been often observed between individuals from different populations and more rarely, within populations. We studied the breeding system of Colutea hispanica using experimental hand pollinations in field conditions in one population in Central Spain in 2004 and 2006. Pollination experiments showed that C. hispanica set fruits from both self and cross-pollinations, suggesting that the species is highly self-compatible. In addition, fruit set was highest following geitonogamy in both years and no flowers set fruits from xenogamy in 2004. Although such enhanced reproductive success following selfing rather than crossing has been largely ignored in many studies on plant reproduction, it seems to be not as rare in plants as previously thought.Los sistemas reproductivos en las plantas se han considerado como mecanismos que promueven los cruzamientos con la finalidad de aumentar la variabilidad genética y evitar la endogamia. Sin embargo se ha observado con frecuencia un reducido éxito reproductor tras cruzamientos entre individuos de diferentes poblaciones, lo que se ha denominado �depresión exogámica� e incluso más raramente entre individuos de la misma población. Se estudió el sistema de cruzamiento de Colutea hispanica mediante la aplicación de polinizaciones manuales en el campo en una población situada en Madrid (España) durante los años 2004 y 2006. Se obtuvieron frutos tanto por autopolinización como por polinización cruzada, sugiriendo que la especie posee un sistema altamente compatible. La alta autocompatibilidad observada podría deberse a una adaptación a condiciones de escasez de polinizadores y de �parejas reproductoras�. El máximo valor de fruit set se alcanzó en los cruzamientos geitonogámicos en ambos años, y en el año 2004 los cruzamientos xenógamos no produjeron ningún fruto. Este último fenómeno parece ser más común entre plantas de lo que en principio se podría pensar, pero ha sido ignorado en la mayor parte de los estudios de biología reproductora

Multiscale assessment of woody species recruitment in Mediterranean shrublands: facilitation and beyond

Aim: Forest recovery in Mediterranean environments is influenced by factors such as aridity, herbivory and facilitation by shrubs, as well as by seed limitation in the case of highly fragmented forests. How these various factors interact can determine the direction of secondary succession, yet these interactions are poorly understood. We assessed the relative importance of several factors in forest species recruitment in Retama sphaerocarpa (L.) Boiss (Retama) shrublands at different spatial scales. Location: Centre of the Iberian Peninsula. Methods: We surveyed mid- and late successional woody species common in Holm oak forests in 29 Retama shrublands that are distributed along an environmental gradient of increasing aridity and herbivory (regional scale) and are located at various distances from forest patches of different sizes (landscape and local scale). In each Retama shrubland, we analysed the effects of microhabitat (under Retama canopy vs open gaps), aridity, presence of nurse shrubs, herbivory, based on the density of pellet droppings, and propagule pressure, measured as the ratio between the size of forest patches acting as seed sources and their distance to Retama shrubs. Results: Quercus ilex, Asparagus acutifolius and Juniperus oxycedrus were the mid- and late successional woody species most recruited in Retama shrublands. Their frequency, which increased with precipitation, was higher under Retama canopy than in gaps. Differences in Q. ilex recruitment between Retama canopy or gaps increased with rainfall, suggesting a decrease in Retama facilitation effectiveness with increasing aridity. Frequency of recruited oaks increased with the total area of woodland remnants located at 0.5 km did not contribute to recruitment. Conclusions: Presence of the shrub R. sphaerocarpa and dispersal-related processes at local scale are main determinants of the colonization of shrublands by late successional woody species. Preserving Retama shrublands and Q. ilex woodland remnants is therefore crucial for extensive passive restoration of Mediterranean oak forests. However, facilitation by Retama is much weaker when both aridity and herbivory are high, regardless of seed source availability.This study was supported by project CGL2014-53308-P SERAVI of the MINECO and the network Remedinal-3 (S2013/MAE-2719) of the Community of Madrid.Peer Reviewe

Compartmentalized and contrasted response of ectomycorrhizal and soil fungal communities of Scots pine forests along elevation gradients in France and Spain

Fungi are principal actors of forest soils implied in many ecosystem services and the mediation of tree's responses. Forecasting fungal responses to environmental changes is necessary for maintaining forest productivity, although our partial understanding of how abiotic and biotic factors affect fungal communities is restricting the predictions. We examined fungal communities of Pinus sylvestris along elevation gradients to check potential responses to climate change-associated factors. Fungi of roots and soils were analysed at a regional scale, by using a high-throughput sequencing approach. Overall soil fungal richness increased with pH, whereas it did not vary with climate. However, when representative sub-assemblages, i.e. Ascomycetes/Basidiomycetes, and families were analysed, they differentially answered to climatic and edaphic variables. This response was dependent on where they settled, i.e. soil versus roots, and/or on their lifestyle, i.e. mycorrhizal or not, suggesting different potential functional weights within the community. Our results revealed a highly compartmentalized and contrasted response of fungal communities in forest soils. The different response of fungal sub-assemblages indicated a range of possible selective direct and indirect (i.e. via host) impacts of climatic variations on these communities, of unknown functional consequences, that helps in understanding potential fungal responses under future global change scenarios