SummaryAfforestation significantly affects soil chemistry and biota, but its effects on the potentially growth-limiting nutrient phosphorus (P) had not to our knowledge been analyzed globally.We conducted a comprehensive meta-analysis of 220 independent sampling sites from 108 articles to evaluate global patterns and controls of soil P change following afforestation.Overall, total P concentration decreased by 11% and total P stock by 12% in the top 20 cm of mineral soil following afforestation, with no change in available P. Time since afforestation had no consistent effect on total P, while available P tended to increase with time. Prior land cover was the most influential factor for soil P change after afforestation, with available P increasing on native vegetation but decreasing on cropland. Afforestation increased available P by 22% without decreasing total P on formerly 'degraded' land, but depleted total P by 15% at nondegraded sites. Climate also influenced soil P response to afforestation, with larger P loss in the tropics.Afforestation did not appear to directly induce P limitation, as available P only decreased on cropland. However, substantial declines in total P may drive tropical plantations toward greater P limitation as the capacity to replenish available P decreases.

Bone morphogenetic proteins (BMPs) belong to the transforming growth factor β (TGFβ) superfamily of secreted molecules. BMPs play essential roles in multiple developmental and homeostatic processes in metazoans. Malfunction of the BMP pathway can cause a variety of diseases in humans, including cancer, skeletal disorders and cardiovascular diseases. Identification of factors that ensure proper spatiotemporal control of BMP signaling is critical for understanding how this pathway is regulated. We have used a unique and sensitive genetic screen to identify the plasma membrane-localized tetraspanin TSP-21 as a key new factor in the C. elegans BMP-like “Sma/Mab” signaling pathway that controls body size and postembryonic M lineage development. We showed that TSP-21 acts in the signal-receiving cells and genetically functions at the ligand-receptor level. We further showed that TSP-21 can associate with itself and with two additional tetraspanins, TSP-12 and TSP-14, which also promote Sma/Mab signaling. TSP-12 and TSP-14 can also associate with SMA-6, the type I receptor of the Sma/Mab pathway. Finally, we found that glycosphingolipids, major components of the tetraspanin-enriched microdomains, are required for Sma/Mab signaling. Our findings suggest that the tetraspanin-enriched membrane microdomains are important for proper BMP signaling. As tetraspanins have emerged as diagnostic and prognostic markers for tumor progression, and TSP-21, TSP-12 and TSP-14 are all conserved in humans, we speculate that abnormal BMP signaling due to altered expression or function of certain tetraspanins may be a contributing factor to cancer development.

Aim Non‐native invasive plants impact ecosystems globally, and the distributions of many species are expanding. The current and potential distributions of many invaders have not been characterized at the broad scales needed for effective management. We modelled the distributions of 15 non‐native invasive grass and forb species of concern in western North America to define their environmental niches and predict potential invasion risk. Location Arid and semi‐arid western United States. Methods We modelled species distribution using presence/absence data from > 148,000 vegetation survey plots to predict the probability of presence of each species based on associated climate, soil, topography and disturbance records. Boosted regression tree models were trained and tested within a buffer distance from presence observations of each species. Buffers were optimized by adding absence observations from increasingly large areas until prediction of presence was maximized, as defined by the area under the precision‐recall curve (AUPRC). We evaluated model AUPRC and other metrics by cross‐validation within training areas, then projected final models within focal EPA level III ecoregions. Results Focal species were present in 2.7% to 21% of plots within model training areas of 40 to 340 km radius. Models conservatively estimated potential species presence, with typically low false positive rates and moderate sensitivity. The most influential predictors of presence included minimum temperature (especially for grasses), climatic water deficit, precipitation seasonality and fire history. Cold desert ecoregions were impacted by the most species, with predicted range expansion into the prairie ecoregions and infilling for Warm Desert species. Main conclusions Invasive forb and grass species are likely to expand their ranges and continued increases in temperature, aridity and area burned will increase invasion risk. Monitoring species presence and absence and mapping known and potential ranges with a focus on presence detection, as in our methodology, will aid in identifying new invasions and prioritizing prevention and control.

Forest communities change in response to shifting climate, changing land use, and species introductions, as well as the interactions of established species. We surveyed the oak (Quercus L. spp.) community and Acorn Woodpecker (Melanerpes formicivorus (Swainson, 1827)) population within 230 ha of oak forest and savanna in central coastal California in 1979 and 2013 to assess demographic changes over a timescale relevant to mature oaks. Overall, percent canopy cover increased, particularly where coast live oak (Quercus agrifolia Née) and California black oak (Quercus kelloggii Newberry) were most abundant. The density of stems of Q. agrifolia increased, whereas the density of stems and basal area of valley oak (Quercus lobata Née), a species favored by Acorn Woodpeckers, decreased. The number of Acorn Woodpeckers and woodpecker territories increased over the study period, coincident with the increase in percent canopy cover; however, these increases were not related spatially. Instead, increased acorn production associated with broad-scale canopy growth likely more than compensated for the loss of Q. lobata. Our findings suggest that forests in this area are becoming denser and savanna is becoming more open, which so far has supported an increase in the Acorn Woodpecker population, despite potential habitat loss if Q. lobata continues to decline.Résumé : Les communautés forestières changent en réponse aux fluctuations climatiques, aux changements dans l'utilisation du territoire et aux introductions d'espèces, de même qu'aux interactions entre espèces établies. Nous avons étudié les communautés de chênes (Quercus L. spp.) et les populations du pic glandivore (Melanerpes formicivorus (Swainson, 1827)) sur 230 ha de chênaie et de savane de la côte centrale californienne en 1979 et en 2013 dans le but d'évaluer les changements démographiques sur une période de temps appropriée pour des chênes matures. Dans l'ensemble, le pourcentage de recouvrement arborescent a augmenté, particulièrement là où le chêne de Californie (Quercus agrifolia Née) et le chêne noir de Californie (Quercus kelloggii Newberry) étaient les plus abondants. La densité de tiges de Q. agrifolia a augmenté, tandis que la densité de tiges et la surface terrière du chêne blanc de Californie (Quercus lobata Née), une espèce favorite du pic glandivore, ont diminué. Le nombre d'individus et de territoires du pic glandivore a augmenté durant la période d'étude, coïncidant avec l'augmentation du pourcentage de couvert arborescent, mais ces augmentations n'étaient pas corrélées spatialement. En fait, la production accrue de glands associée à l'augmentation à grande échelle du couvert arborescent a probablement surcompensé la perte de Q. lobata. Nos résultats suggèrent que les forêts de cette région se densifient tandis que les savanes deviennent plus clairsemées, ce qui jusqu'à maintenant a permis un accroissement des populations du pic glandivore, en dépit d'un déclin potentiel si la population de Q. lobata continue à décroître. [Traduit par la Rédaction] Mo...