Relació entre la vegetació i els paràmetres ambientals als boscos pirinencs de pi roig (Pinus sylvestris L.)

S'estudia la relació de la vegetació dels boscos pirinencs de pi roig (Pinus sylvestris L.) amb els paràmetres ambientals (p.e., altitud, radiació solar, nutrients al sòl, etc.) mitjançant mètodes d'andisi multivariant (ordenació, classificació i anàlisi canònica). Els resultats suggereixen que existeix una forta relació entre la vegetació i els paràmetres ambientals. Aquests boscos on l'única espècie arbòria és el pi roig, poden ser dividits en diierentes comunitats ecològicament diferenciades. Els principals paràmetres que determinen la vegetació corresponen a la capacitat de bescanvi catiònic del sòl i a la radiació solar incident.The relation between vegetation and their environment (e.g., altitude, solar radiation, soil nutrients) is studied in Pyrenean Scots pine (Pinus sylvestris L.) forests by means of multivariate analyses (i.e., ordination, classification and canonical analysis). The results suggest a strong correlation between vegetation and the environment. Although these forests are dominated by one overstorey species they can be subdivided into several ecologically differentiated communities. Cation exchange capacity and incoming solar radiation are the main parameters determining the vegetation composition

Estructura en l'espai del sotabosc als boscos pirinencs de pi roig (Pinus sylvestris L.)

A partir d'un mostreig basat en transectes a 59 parcel·les de bosc de pi roig (Pinus sylvestris L.), s'estudia el comportament en l'espai (dins les parce1,les) que presenten les espècies. El mètode utilitzat es basa en el càlcul del coeficient d'autocorrelació de cada espècie en cada parcel·la. Els resultats suggereixen que les espècies als boscos estudiats tendeixen a distribuir-se formant claps (distribució agregada), i no pas amb una distribució uniforme o a l'atzar, i que existeix certa relació entre el patró de distribució de les diferentes espècies i la seva forma vital.Spatial pattern of understorey species in Pyrenean Scots pine forests was studied from transect data in 59 plots. Autocorrelation coefficient was computed for each species in each plot. The results suggest that most of the species tend to show a clumped pattern, rather than random or uniform pattern, and that there is some relationship between the spatial pattern of the different species and their life form

Disturbance ecology in human societies

1. We define societal disturbances as discrete events that abruptly disrupt the functioning of human societies. There is a variety of such events, including hurricanes, floods, epidemics, nuclear accidents, earthquakes and wars, among others. These disturbances can interact, further increasing their impacts. The severity of disturbances does not only depend on their intrinsic properties (type, intensity and magnitude) but also greatly on human aspects (socioeconomic, historical, political and cultural aspects that define vulnerability). 2. Very large or severe disturbances are infrequent and unpredictable. Yet societal disturbances are intrinsic to human societies; they have occurred through the entire human history and will continue to occur in the future. We can increase preparedness and recovery capacity but cannot avoid disturbances. The type, regime and scale of disturbances change with the development of societies. The increase in population density and complexity also increases the severity of many disturbances. 3. Societal disturbances can temporarily disrupt the functioning of societies. However, when those disturbances are frequent, societies adapt to them and thus disturbances contribute to shape cultural evolution. That is, societal disturbances have a cost at short temporal scales, but they can build up resilience at mid-to long-term scales. 4. Understanding this dynamic view of human systems is becoming more important as climate is changing, humans are overexploiting natural resources and humanity is dense and hyperconnected. We need to take advantage of frequent small disturbances, as they can build resilience and reduce the likelihood of infrequent large and severe disturbances. Our challenge is to encourage actions and policies to be prepared for unknown, unpredictable and unprecedented (infrequent) large-scale societal disturbances that will surely arrive

Differential pollinator response underlies plant reproductive resilience after fires

Background and aims Assessing the resilience of plant-animal interactions is critical to understanding how plant communities respond to habitat disturbances. Most ecosystems experience some level of natural disturbance (e. g., wildfires) to which many organisms are adapted to. Wildfires have structured biotic communities for millennia; however, the effects of fire on interactions such as pollination have only recently received attention. A few studies have shown that generalist plants can buffer the impact of fires by pollinator replacement, suggesting that the resilience to disturbance could depend on the level of specialization of the interactions. Here, we hypothesize that i) fires could impose negative effects on plants with specialized pollination systems, and ii) in large wildfires, these negative effects will be stronger with increasing distance inside the burnt because pollinators will need more time to recolonize. Methods These questions were tested in the specialized pollination system of a widespread Mediterranean palm, Chamaerops humilis. The postfire pollination resilience was assessed in replicated wildfires representing three postfire ages by measuring the abundance of beetle pollinators and by estimating fruit set (i.e., proportion of flowers setting fruits) in burnt and unburned areas. To test for distance effects, plants were sampled along transects inside the burnt. Key results This study revealed that despite a marked postfire decline in the specialist pollinator, exacerbated by the distance from the fire’s edge, the palm’s fruit set was barely affected. The temporary replacement by a sap beetle at burnt sites - an effective pollinator that had not been previously recognized - provided postfire reproductive resilience. Conclusions The study shows that differential pollinator responses to disturbance can ensure plant success even in plants with only two functionally similar pollinators. This highlights the importance of pollinator 1 replacement and dynamics for the resilience of interactions and ultimately of plant reproduction in disturbance-prone ecosystems

Towards an understanding of the evolutionary role of fire in animals

Wildfires underpin the dynamics and diversity of many ecosystems worldwide, and plants show a plethora of adaptive traits for persisting recurrent fires. Many fire-prone ecosystems also harbor a rich fauna; however, knowledge about adaptive traits to fire in animals remains poorly explored. We review existing literature and suggest that fire is an important evolutionary driver for animal diversity because (1) many animals are present in fire-prone landscapes and may have structural and phenotypic characters that contribute to adaptation to these open landscapes; and (2) in some cases, animals from fire-prone ecosystems may show specific fire adaptations. While there is limited evidence on morphological fire adaptations in animals, there is evidence suggesting that different behaviors might provide a rich source of putative fire adaptations; this is because, in contrast to plants, most animals are mobile, unitary organisms, have reduced survival when directly burnt by fire and can move away from the fire. We call for research on fire adaptations (morphological, behavioral, and physiological) in animals, and emphasize that in the animal kingdom many fire adaptations are likely to be behavioral. While it may be difficult to discern these adaptations from other animal behaviors, making this distinction is fundamental if we want to understand the role of fire in shaping biodiversity. Developing this understanding is critical to how we view and manage our ecosystems in the face of current global and fire regime changes.This research was funded by the project FILAS (CGL2015-64086-P) from the Spanish Government (Ministerio de Economía y Competitividad) and the PROMETEO/2016/021 project from the Valencia government (Generalitat Valenciana, Spain)Peer reviewe

Environmental policies to cope with novel disturbance regimes–steps to address a world scientists’ warning to humanity

ABL acknowledges postdoctoral funding from the Alexander von Humboldt Foundation and grants RTI2018-096187-J-100 from FEDER/ Ministerio de Ciencia, Innovacion y Universidades and LRB20/1002 from the British Ecological Society.Alexander von Humboldt Foundation RTI2018-096187-J-100FEDER/ Ministerio de Ciencia, Innovacion y Universidades LRB20/1002British Ecological Societ

Divergent selection in a Mediterranean pine on local spatial scales

1. The effects of selection on an organism's genome are hard to detect on small spatial scales, as gene flow can swamp signatures of local adaptation. Therefore, most genome scans to detect signatures of environmental selection are performed on large spatial scales; however, divergent selection on the local scale (e.g. between contrasting soil conditions) has also been demonstrated, in particular for herbaceous plants. 2. Here, we hypothesised that in topographically complex landscapes, microenvironment variability is strong enough to leave a selective footprint in the genomes of long-lived organisms. To test this, we investigated paired south- versus north-facing Pinus pinaster stands on the local scale, with trees growing in close vicinity (≤820 m distance between paired south- and north-facing stands), in a Mediterranean mountain area. While trees on north-facing slopes experience less radiation, trees on south-facing slopes suffer from especially harsh conditions, particularly during the dry summer season. 3. Two outlier analyses consistently revealed five putatively adaptive loci (out of 4034), in candidate genes two of which encoded non-synonymous substitutions. Additionally, one locus showed consistent allele frequency differences in all three stand pairs indicating divergent selection despite high gene flow on the local scale. Permutation tests demonstrated that our findings were robust. 4. Functional annotation of these candidate genes revealed biological functions related to abiotic stress response, such as water availability, in other plant species. 5. Synthesis. Our study highlights how divergent selection in heterogeneous microenvironments shapes and maintains the functional genetic variation within populations of long-lived forest tree species, being the first to focus on adaptive genetic divergence between south- and north-facing slopes within continuous forest stands. This is especially relevant in the current context of climate change, as this variation is at the base of plant population responses to future climate.European Commission http://dx.doi.org/10.13039/501100000780European Science Foundation http://dx.doi.org/10.13039/501100000782Spanish Ministry of Science and Innovation http://dx.doi.org/10.13039/501100004837University of BrodeauxPeer Reviewe

Towards understanding resprouting at the global scale

Understanding and predicting plant response to disturbance is of paramount importance in our changing world. Resprouting ability is often considered a simple qualitative trait and used in many ecological studies. Our aim is to show some of the complexities of resprouting while highlighting cautions that need be taken in using resprouting ability to predict vegetation responses across disturbance types and biomes. There are marked differences in resprouting depending on the disturbance type, and fire is often the most severe disturbance because it includes both defoliation and lethal temperatures. In the Mediterranean biome, there are differences in functional strategies to cope with water deficit between resprouters (dehydration avoiders) and nonresprouters (dehydration tolerators); however, there is little research to unambiguously extrapolate these results to other biomes. Furthermore, predictions of vegetation responses to changes in disturbance regimes require consideration not only of resprouting, but also other relevant traits (e.g. seeding, bark thickness) and the different correlations among traits observed in different biomes; models lacking these details would behave poorly at the global scale. Overall, the lessons learned from a given disturbance regime and biome (e.g. crown-fire Mediterranean ecosystems) can guide research in other ecosystems but should not be extrapolated at the global scale.This work was performed under the framework of the TREVOL projects (CGL2012-39938-C02-01 to J.G.P.) from the Spanish Government. A.L.J., R.B.P., A.V. and S.P. were supported by the following grants: IOS-1252232 (NSF), IOS-0845125 (NSF), CGL-2011-30531-CO2-02 (SURVIVE Project, Spain), ID-1120458 (Fondo Nacional de Desarrollo Científico y Tecnológico, FONDECYT, Chile), respectively