Cordyla pinnata is a multipurpose forage species that plays important ecological and socio-economic roles in sub-Saharan Africa. We investigated how different land use types affect the species' population structure and distribution in Senegal. Forest inventories were conducted in 140 plots across four land use types: farmland, fallow, rangeland, and protected area. Diameter at breast height (dbh), crown diameter, height, and regeneration of C. pinnata were measured, and woody species composition was noted. The results showed significant differences in species composition across land use types, with protected areas and rangelands showing the highest species diversity. The density of mature C. pinnata trees was highest in protected areas (393.63 +/- 24.21 stems/ha) and lowest in farmlands (140.40 +/- 46.70 stems/ha), suggesting that agricultural expansion has a strong negative impact on the species. Diameter class distributions suggested a stable population structure of mature trees, whereas regeneration patterns revealed an unstable state, raising concerns about the species' future sustainability. Our findings underscore the adverse effects of land use changes on C. pinnata and highlight the need to mitigate human pressure on ecosystems to ensure conservation of this valuable species and the biodiversity it supports. Cordyla pinnata est une esp & egrave;ce fourrag & egrave;re polyvalente d'importance & eacute;cologique et socio-& eacute;conomique & eacute;lev & eacute;e en Afrique subsaharienne. Nous avons & eacute;valu & eacute; l'effet de diff & eacute;rents types d'utilisation du sol sur la structure des populations et la r & eacute;partition spatiale de l'esp & egrave;ce au S & eacute;n & eacute;gal. Des inventaires ont & eacute;t & eacute; r & eacute;alis & eacute;s dans 140 placettes au sein de quatre cat & eacute;gories d'utilisation des terres : champs cultiv & eacute;s, jach & egrave;res, p & acirc;turages et aires prot & eacute;g & eacute;es. Le diam & egrave;tre & agrave; hauteur de poitrine (DHP), le diam & egrave;tre de la cime, la hauteur, ainsi que la r & eacute;g & eacute;n & eacute;ration ont & eacute;t & eacute; mesur & eacute;s. La composition sp & eacute;cifique d'esp & egrave;ces ligneuses a aussi & eacute;t & eacute; not & eacute;e. Les r & eacute;sultats r & eacute;v & egrave;lent des diff & eacute;rences significatives de composition sp & eacute;cifique entre les milieux, les aires prot & eacute;g & eacute;es et les p & acirc;turages pr & eacute;sentant les niveaux de diversit & eacute; sp & eacute;cifique les plus & eacute;lev & eacute;s. La densit & eacute; des arbres matures de C. pinnata & eacute;tait plus & eacute;lev & eacute;e dans les aires prot & eacute;g & eacute;es (393,63 +/- 24,21 tiges/ha) que dans les champs cultiv & eacute;s (140,40 +/- 46,70 tiges/ha), indiquant que l'expansion agricole constitue une pression n & eacute;gative importante sur l'esp & egrave;ce. La distribution des classes de diam & egrave;tre met en & eacute;vidence une structure adulte globalement stable, tandis que les tendances observ & eacute;es pour la r & eacute;g & eacute;n & eacute;ration t & eacute;moignent d'un & eacute;tat instable semant le doute quant & agrave; la durabilit & eacute; des populations. Nos observations soulignent les effets n & eacute;gatifs des changements d'utilisation des terres sur C. pinnata et la n & eacute;cessit & eacute; de limiter les impacts anthropiques sur les & eacute;cosyst & egrave;mes de mani & egrave;re & agrave; assurer la conservation de cette esp & egrave;ce d'int & eacute;r & ecirc;t et la biodiversit & eacute; qu'elle soutient.
Michoacan possesses extensive forest cover yet has undergone rapid and sustained land use transformations driven by illegal logging and the expansion of the 'avocado strip'. This study utilized Random Forest (RF) classification of Landsat imagery (1986-2025) to analyze landscape dynamics, identifying Near-Infrared (NIR) and Shortwave Infrared 2 (SWIR 2) bands as the most critical predictors. Change detection analysis revealed severe deforestation: dry forest declined by 4,344 km(2) and evergreen forest by 1,698 km(2), fueling a corresponding increase in exposed soils (3,270 km(2)) and croplands (2,158 km(2)). To assess ecological impacts, MaxEnt was employed to model the distribution of 35 vulnerable species (16 Near Threatened, 10 Vulnerable, and 9 Endangered) with Nighttime Land Surface Temperature in December emerging as the most influential variable. The biodiversity assessment (2000-2025) indicated that the Reddish Egret (Egretta rufescens) suffered the greatest loss of potential distribution area (exceeding 50%), while the Grey Plover (Pluvialis squatarola) and the Mexican Ground Pit Viper (Agkistrodon bilineatus) exhibited the greatest gains (approximately 50% increase). Given that these threatened ecosystems are poorly represented within current protected areas, these findings underscore an urgent need to integrate conservation strategies into regions undergoing intense agricultural conversion to mitigate further biodiversity loss.
The growing presence of domestic dogs (Canis lupus familiaris) in protected natural areas (PAs), particularly in those located near cities, poses a threat to native fauna through disease transmission, antagonistic interactions, and hybridization. Mexico has one of the world's largest dog populations, and urbanization is threatening several of its protected areas (PAs) and their wildlife. To assess the potential for antagonistic interactions, we analyzed the spatial and temporal activity patterns of dogs and three native mesocarnivores-Canis latrans, Lynx rufus, and Urocyon cinereoargenteus-in the peri-urban National Park Barranca del Cupatitzio (NPBC) in western Mexico. From January 2023 to March 2024, we set up 10 camera traps throughout the NPBC to survey mammal activity. Urocyon cinereoargenteus had the highest recording frequency (n = 253), and L. rufus (n = 25) had the lowest recording. Canis latrans and C. lupus familiaris had the greatest overlap in daily activity (triangle=0.81), while C. lupus familiaris and L. rufus had the least (triangle=0.58). The species with the highest spatial coincidence were C. latrans and U. cinereoargenteus (Jaccard index = 0.84), and the species with the least were L. rufus and C. latrans (Jaccard index = 0.28). There is a high potential for dogs to affect native fauna negatively.
We investigated the importance of throughfall nutrient fluxes to stand-level nutrient use efficiency across a gradient of soil fertility and tree species composition in northern Lower Michigan, USA. Potassium (K) was most susceptible to canopy leaching with annual throughfall K fluxes averaging 1.37 g m-2, compared to 0.32 g m-2 for calcium (Ca), 0.27 g m-2 for nitrogen (N), 0.13 g m-2 for magnesium (Mg) and 0.07 g m-2 for phosphorus (P). Throughfall losses of K exceeded litterfall losses and accounted for 43-77% of the total flux of K from canopy to soil. Thus, accounting for leaching losses reduced estimates of stand level K use efficiency by 2-4 times compared to estimates that only accounted for K losses in litterfall. In contrast, throughfall fluxes of Ca and N were very low, such that accounting for leaching losses of these elements had a negligible impact on estimates of stand-level Ca and N use efficiency. Throughfall fluxes of P and Mg accounted for 15-30% of total canopy fluxes, but these estimates are likely inflated by wash off of dry deposition. In summary, the K economy of these temperate deciduous forest stands cannot be understood without accounting for throughfall leaching losses. Nous avons & eacute;tudi & eacute; l'importance du pluviolessivage sur l'efficacit & eacute; d'utilisation des nutriments & agrave; l'& eacute;chelle du peuplement le long d'un gradient de fertilit & eacute; du sol et de composition en esp & egrave;ces d'arbres dans le nord de la p & eacute;ninsule inf & eacute;rieure du Michigan (& Eacute;tats-Unis). Le potassium (K) & eacute;tait le plus sensible au pluviolessivage, avec un flux annuel moyen de 1,37 g m-2, comparativement & agrave; 0,32 g m-2 pour le calcium (Ca), 0,27 g m-2 pour l'azote (N), 0,13 g m-2 pour le magn & eacute;sium (Mg) et 0,07 g m-2 pour le phosphore (P). Les pertes de K par pluviolessivage & eacute;taient sup & eacute;rieures & agrave; celles associ & eacute;es & agrave; la chute de liti & egrave;re et repr & eacute;sentaient 43-77% du flux total de K de la canop & eacute;e vers le sol. Ainsi, tenir compte des pertes par pluviolessivage r & eacute;duit de deux & agrave; quatre fois les estimations d'efficacit & eacute; d'utilisation du K & agrave; l'& eacute;chelle du peuplement comparativement aux estimations ne tenant compte que des pertes par chute de liti & egrave;re. & Agrave; l'oppos & eacute;, les flux de Ca et de N par pluviolessivage & eacute;taient tr & egrave;s faibles, si bien que d'en tenir compte avait un effet n & eacute;gligeable sur les estimations d'efficacit & eacute; d'utilisation de Ca et de N & agrave; l'& eacute;chelle du peuplement. Les flux de pluviolessivage de P et de Mg repr & eacute;sentaient 15-30% des flux totaux, mais ces estimations sont vraisemblablement influenc & eacute;es par le lessivage de d & eacute;p & ocirc;ts secs. En somme, l'& eacute;conomie du K de ces for & ecirc;ts temp & eacute;r & eacute;es feuillues ne peut & ecirc;tre comprise sans tenir compte des pertes par pluviolessivage.
Dutch elm disease (DED) spread throughout the United States in the 20th century and resulted in mortality of many elm trees. In this study, bearing trees from Indiana's historical Public Land Survey (PLS) records were used to reconstruct species mingling, diameter differentiation, and competition indices of elm prior to the introduction of DED. Prior to DED spread, elm had an average species mingling index of 0.77, a diameter differentiation index of 0.36, and a competition index of 1.22. Forests where elm had significantly lower mingling indices occurred along rivers. Forests where elm had significantly lower diameter differentiation indices were located near the homeland of the Piankashaw Tribe, which later became the French settlement of Vincennes. Forests where elm had significantly higher diameter differentiation indices were in areas that experienced later settlement by Europeans. Competition indices for elm were regularly dispersed across the state with no significant spatial clustering. This study demonstrated the impact of physiography and human activities on the structure of elm prior to the spread of DED and documented the successful application of PLS records to provide an ecological baseline of elm prior to the introduction of a non-native pathogen. La maladie hollandaise de l'orme (MHO) s'est r & eacute;pandue aux & Eacute;tats-Unis au XXe si & eacute;cle, entra & icirc;nant la mortalit & eacute; de nombreux ormes. Dans cette & eacute;tude, des arbres rep & eacute;res des archives d'arpentage des terres publiques de l'Indiana ont & eacute;t & eacute; utilis & eacute;s pour reconstituer des indices de mixit & eacute; d'esp & eacute;ces, de diff & eacute;renciation des diam & eacute;tres et de comp & eacute;tition pour l'orme. Avant l'introduction de la MHO, l'orme avait un indice de mixit & eacute; moyen de 0,77, un indice de diff & eacute;renciation des diam & eacute;tres de 0,36 et un indice de comp & eacute;tition de 1,22. L'indice de mixit & eacute; & eacute;tait significativement plus faible dans les for & ecirc;ts ripariennes. L'indice de diff & eacute;renciation des diam & eacute;tres & eacute;tait significativement plus faible dans les for & ecirc;ts du territoire de la Nation Piankashaw, qui est plus tard devenu l'& eacute;tablissement fran & ccedil;ais de Vincennes. L'indice de diff & eacute;renciation des diam & eacute;tres & eacute;tait significativement plus & eacute;lev & eacute; dans les zones colonis & eacute;es plus tardivement par les Europ & eacute;ens. Aucun patron spatial particulier n'a & eacute;t & eacute; not & eacute; en ce qui concerne l'indice de comp & eacute;tition. Cette & eacute;tude a montr & eacute; les effets de la physiographie et des activit & eacute;s humaines sur la structure des peuplements d'orme avant l'introduction de la MHO, en plus de fournir un exemple d'utilisation des archives d'arpentage comme base de comparaison historique avant l'introduction d'un pathog & eacute;ne exotique.
Predator-prey interactions are fundamental to ecosystem dynamics, as prey traits and environmental context jointly shape predation risk and predator behaviour. Preys have developed various strategies to evade predators with morphological adaptations like body colouration and behavioural changes to deter or escape their predators. Using an artificial caterpillar model, we tested the relationship between prey aggregation, body colouration, and the interplay of habitat structure with the likelihood of artificial prey being predated by visually oriented vertebrates within an urban-agricultural area in the Philippines. Of the 1026 observed prey items, 204 were attacked, primarily by mammals (75%), then birds (17%) and reptiles (8%). Contrary to our initial hypothesis, prey colouration did not influence predation risk. Instead, prey aggregation was the primary determinant of the likelihood of attack. Habitat structure variables also influenced predation. We suggest that predation risk is highest in aggregated prey, regardless of body colouration, challenging the expectations of aposematic effects in human-altered environments. This highlights the need to reassess predator-prey dynamics in these ecosystems, emphasise context-specific studies to understand ecological interactions, and call for further research on species interactions and environmental health indicators. Les interactions pr & eacute;dateur-proie sont fondamentales pour la dynamique des & eacute;cosyst & egrave;mes, car les caract & eacute;ristiques des proies et le contexte environnemental d & eacute;terminent conjointement le risque de pr & eacute;dation et le comportement des pr & eacute;dateurs. Les proies ont d & eacute;velopp & eacute; diverses strat & eacute;gies pour & eacute;chapper aux pr & eacute;dateurs, notamment des adaptations morphologiques telles que la coloration du corps et des changements de comportement visant & agrave; repousser les pr & eacute;dateurs ou & agrave; leur & eacute;chapper. & Agrave; l'aide d'un mod & egrave;le artificiel de chenille, nous avons test & eacute; l'effet de l'agr & eacute;gation des proies, de leur couleur et de la structure de l'habitat sur la probabilit & eacute; que les proies artificielles soient pr & eacute;dat & eacute;es par des vert & eacute;br & eacute;s & agrave; orientation visuelle dans une zone urbaine et agricole des Philippines. Sur les 1026 proies observ & eacute;es, 204 ont & eacute;t & eacute; attaqu & eacute;es, principalement par des mammif & egrave;res (75%), puis par des oiseaux (17%) et des reptiles (8%). Contrairement & agrave; notre hypoth & egrave;se initiale, la couleur des proies n'a pas influenc & eacute; le risque de pr & eacute;dation. C'est plut & ocirc;t l'agr & eacute;gation des proies qui a & eacute;t & eacute; le principal facteur influen & ccedil;ant la probabilit & eacute; d'attaque. Les variables li & eacute;es & agrave; la structure de l'habitat ont & eacute;galement influenc & eacute; la pr & eacute;dation. Nous sugg & eacute;rons que le risque de pr & eacute;dation est plus & eacute;lev & eacute; chez les proies regroup & eacute;es, quelle que soit leur couleur, ce qui remet en question les hypoth & egrave;ses d'effets apos & eacute;matiques dans les environnements modifi & eacute;s par l'humain. Cela souligne la n & eacute;cessit & eacute; de r & eacute;& eacute;valuer la dynamique pr & eacute;dateur-proie dans ces & eacute;cosyst & egrave;mes, de mettre l'accent sur des & eacute;tudes tenant compte du contexte pour comprendre les interactions & eacute;cologiques, et de r & eacute;aliser des recherches suppl & eacute;mentaires sur les interactions entre les esp & egrave;ces et les indicateurs de sant & eacute; environnementale.
Congeneric species often exhibit intense competitive interactions due to their shared exploitation of resources. This study investigated habitat use patterns in two parapatric Iberian viper species, Vipera aspis and Vipera latastei. Habitats were described in terms of plant communities, and community turnover was evaluated using Moran's correlograms, along with climatic and spatial factors that accounted for this turnover. Marked differences in habitat turnover rates were found between the two viper species. In V. aspis, the analysis indicated the use of more heterogeneous environments, with spatial clustering disappearing at intermediate distances (71.4 km). In V. latastei, the loss of spatial clustering occurred at considerably greater distances (246.4 km), and a core set of plant species persisted across habitats, even over long distances (up to 500 km). Climate was an important factor shaping habitat turnover, explaining 19.3% of the variability in V. aspis and 21.2% in V. latastei. Spatial factors were more influential for V. latastei (24.5%) than for V. aspis (9.8%). Our results also indicated that V. aspis and V. latastei occupy ecologically complementary areas, yet exhibit overlap within a sub-Mediterranean ecotone. Both species prefer habitats with high plant richness, suggesting an affinity for undisturbed environments offering greater prey density. Les esp & egrave;ces appartenant au m & ecirc;me genre pr & eacute;sentent souvent des interactions comp & eacute;titives intenses en raison de leur exploitation commune des ressources. Les patrons d'utilisation de l'habitat ont & eacute;t & eacute; & eacute;tudi & eacute;s chez deux esp & egrave;ces de vip & egrave;res ib & eacute;riques parapatriques, Vipera aspis et Vipera latastei. Les habitats ont & eacute;t & eacute; d & eacute;crits en termes de communaut & eacute;s v & eacute;g & eacute;tales et le renouvellement des communaut & eacute;s a & eacute;t & eacute; & eacute;valu & eacute; & agrave; l'aide de corr & eacute;logrammes de Moran ainsi que des facteurs climatiques et spatiaux qui ont contribu & eacute; & agrave; ce renouvellement. Des diff & eacute;rences marqu & eacute;es ont & eacute;t & eacute; observ & eacute;es entre les deux esp & egrave;ces de vip & egrave;res en ce qui concerne le taux de renouvellement de l'habitat. Chez V. aspis, l'analyse a r & eacute;v & eacute;l & eacute; l'utilisation d'environnements plus h & eacute;t & eacute;rog & egrave;nes, avec une disparition du regroupement spatial aux distances interm & eacute;diaires (71,4km). Chez V. latastei, la perte de regroupement spatial s'est produite & agrave; des distances consid & eacute;rablement plus grandes (246,4km), et un noyau d'esp & egrave;ces v & eacute;g & eacute;tales persistait dans tous les habitats, m & ecirc;me sur de longues distances (jusqu'& agrave; 500km). Le climat & eacute;tait un facteur important dans le renouvellement de l'habitat, expliquant 19,3 % de la variabilit & eacute; chez V. aspis et 21,2 % chez V. latastei. Les facteurs spatiaux & eacute;taient plus importants pour V. latastei (24,5 %) que pour V. aspis (9,8 %). Nos r & eacute;sultats ont aussi indiqu & eacute; que V. aspis et V. latastei occupent des zones & eacute;cologiquement compl & eacute;mentaires, mais pr & eacute;sentent un chevauchement au sein d'un & eacute;cotone subm & eacute;diterran & eacute;en. Les deux esp & egrave;ces pr & eacute;f & egrave;rent les habitats pr & eacute;sentant une richesse v & eacute;g & eacute;tale & eacute;lev & eacute;e, ce qui sugg & egrave;re une affinit & eacute; pour les environnements intacts offrant une plus grande densit & eacute; de proies.
Ecological and neural networks share fundamental principles of adaptation and learning. Here, we reformulate the Lotka-Volterra model of species interactions as a neural network model. This transformation enables adaptive modification of interaction coefficients based on the difference between expected (i.e. predicted) and actual population size. This mechanism is analogous to synaptic plasticity in the brain, where neurons minimize the discrepancy between actual and expected activity. Our simulations reveal that ecological systems can 'learn,' adjusting interactions to support larger predator populations under changing environmental conditions. This suggests that ecological networks, like neural networks, self-organize through predictive adaptation, which was shown to also maximize metabolic energy. Thus, prediction-based adjustment of interactions may offer a unifying framework for understanding biological complexity across scales: from the single-cell level (i.e. neurons) to the interactions at the level of animal species.
Ficus (fig) plants are one of the most important food sources in tropical and subtropical areas. While studies have investigated fig-bird interactions, the knowledge for Taiwan is comparatively modest. Therefore, the goal of this study was to learn more about the natural history of avian frugivores in urban fig trees in Taiwan using observational surveys. During almost 250h of observation, we recorded the species richness and prevalence of birds in 33 fig trees. Visitation rates of fig trees were related to fruit abundance and time of day. Furthermore, we showed that bird species richness in urban fig trees was lower than in non-urban fig trees, and that the few species which dominated in urban fig trees were a small subset of the native and introduced bird species found in the surrounding urban bird communities. Since we observed a relatively high prevalence of introduced bird species in fig trees, we suggest that the year-round availability of figs is an additional factor for introduced bird species to be able to successfully establish themselves. Thus, fig trees appear to be an important resource for urban frugivorous birds and especially for introduced bird species which are already familiar with figs from their native countries.
The expansion of cities has had severe effects on biodiversity. However, within cities, green areas are suitable habitats for diverse species, both native and exotic. This study quantified the population abundances and temporal variations of 16 native and four exotic species of birds that inhabit urban green areas of Mexico City, which is considered a megacity. We used N-mixture models to estimate the abundance of these species. These demographic models also estimate their detection probabilities. We found that six species of birds (three native and three exotic) had remarkably higher abundances than the rest of the species. Eight species had seasonal changes in their abundances, with six of these species increasing in numbers during the dry season and the other two species being more abundant during the rainy season. Some native bird species had higher population numbers in parks with large trees of diverse species, abundant flowers, less urban cover, and low noise levels. In contrast, exotic species were more abundant in parks with intense human activity, where they can easily find anthropogenic food sources. Our findings provide fundamental information about the ecological traits of urban green areas that allow native and exotic birds to thrive in urban ecosystems. L'& eacute;talement urbain a des effets importants sur la biodiversit & eacute;. Toutefois, les espaces verts dans les villes sont des habitats favorables pour diff & eacute;rentes esp & egrave;ces indig & egrave;nes et exotiques. Cette & eacute;tude a quantifi & eacute; l'abondance et les patrons de variation temporelle de 16 esp & egrave;ces indig & egrave;nes et quatre esp & egrave;ces exotiques d'oiseaux dans des espaces verts (parcs urbains) de la ville de Mexico, consid & eacute;r & eacute;e comme une m & eacute;gapole. Nous avons utilis & eacute; des mod & egrave;les N-m & eacute;lange pour estimer l'abondance de ces esp & egrave;ces ainsi que leur probabilit & eacute; de d & eacute;tection. Nous avons trouv & eacute; que six esp & egrave;ces d'oiseaux (trois indig & egrave;nes et trois exotiques) avaient des abondances notablement plus & eacute;lev & eacute;es que les autres esp & egrave;ces. L'abondance de huit esp & egrave;ces changeait selon les saisons : six dont l'abondance augmentait durant la saison s & egrave;che et deux dont l'abondance & eacute;tait plus & eacute;lev & eacute;e durant la saison des pluies. L'abondance de certaines esp & egrave;ces indig & egrave;nes & eacute;tait plus & eacute;lev & eacute;e dans les parcs avec de gros arbres d'esp & egrave;ces vari & eacute;es, beaucoup de fleurs, moins de couvert urbain, ainsi que de faibles niveaux de bruit. Les esp & egrave;ces exotiques & eacute;taient plus abondantes dans les parcs avec beaucoup d'activit & eacute; humaine, o & ugrave; elles trouvaient facilement des sources anthropiques de nourriture. Nos r & eacute;sultats fournissent de l'information importante sur les traits & eacute;cologiques des espaces verts urbains qui permettent aux esp & egrave;ces d'oiseaux indig & egrave;nes et exotiques de prosp & eacute;rer dans les & eacute;cosyst & egrave;mes urbains.
Canada's mountain ecosystems are changing as a result of climate change and a host of natural and anthropogenic disturbances. Understanding the kinds, rates, and causes for those changes is important for informed ecosystem management. To assess changes in the vegetation of Jasper National Park (JNP), we documented changes in plant community composition by resampling 41 ecological land classification (ELC) plots first assessed in the 1970s. In 2023, we documented the presence and percent cover of vascular, hepatic, moss, and lichen species within each plot and compared those data to the 1970s data. Within each plot, we determined the change in cover for each taxon. The communities have become more species rich since the 1970s and community type diversity has increased. Despite rates of species turnover that exceed 50%, plant diversity shows no signs of decline. Multidecadal succession, perhaps influenced by climatic change and human disturbances, is altering the vegetation composition independent of wildfire and mountain pine beetle. Ecologically important species that decreased over time included Pinus contorta, Rosa acicularis, Vaccinium cespitosum, V. scoparium, and V. vitis-idaea. Important increasers included Picea glauca, Pseudotsuga menziesii, and Hylocomium splendens. Younger and drier sites changed more than did older and moister sites. Les & eacute;cosyst & egrave;mes montagneux du Canada changent en r & eacute;ponse au changement climatique et aux perturbations naturelles et anthropiques. Comprendre les types, les taux et les causes de ces changements est important pour & eacute;clairer les d & eacute;cisions d'am & eacute;nagement. Pour & eacute;valuer les changements de v & eacute;g & eacute;tation au Parc national Jasper, nous avons r & eacute;& eacute;chantillonn & eacute; 41 parcelles de classification & eacute;cologique inventori & eacute;es dans les ann & eacute;es 1970. En 2023, nous avons document & eacute; la pr & eacute;sence et le pourcentage de couvert de plantes vasculaires, d'h & eacute;patiques, de mousses et de lichens dans chaque parcelle et nous avons compar & eacute; les donn & eacute;es avec celles des ann & eacute;es 1970. Dans chaque parcelle, nous avons d & eacute;termin & eacute; le changement de couvert pour chaque taxon. Les communaut & eacute;s sont devenues plus riches depuis les ann & eacute;es 1970 et la diversit & eacute; de types de communaut & eacute;s a augment & eacute;. En d & eacute;pit de taux de remplacement d'esp & egrave;ces sup & eacute;rieurs & agrave; 50 %, la diversit & eacute; v & eacute;g & eacute;tale ne montre pas de signe de diminution. La succession multid & eacute;cennale, peut-& ecirc;tre influenc & eacute;e par le changement climatique et les perturbations anthropiques, alt & egrave;re la composition v & eacute;g & eacute;tale ind & eacute;pendamment des incendies forestiers et des & eacute;pid & eacute;mies de dendroctone du pin. Les esp & egrave;ces d'importance & eacute;cologique ayant diminu & eacute; incluent Pinus contorta, Rosa acicularis, Vaccinium cespitosum, V. scoparium et V. vitis-idaea. Celles qui ont augment & eacute; incluent Picea glauca, Pseudotsuga menziesii et Hylocomium splendens. Les sites plus jeunes et plus secs ont chang & eacute; plus que les sites plus vieux et plus humides.
Through their various activities, pinnipeds alter the dynamics of plant communities in coastal ecosystems. Thus, the use of coastal environments as winter breeding grounds by grey seals, in response to the disappearance of sea ice, represents a potential threat to the ecological integrity of terrestrial dune ecosystems bordering the Gulf of St. Lawrence in Eastern Canada. In this study, we characterize the impact of grey seals on the dune ecosystem of the & Icirc;le-Brion ecological reserve by comparing vegetation cover (density and biomass) and the physicochemical properties of substrates and leaf tissues of Calamagrostis breviligulata between sites occupied by the seal colony and control sites. Our results indicate that the grey seal colony plays a role in the transfer of allochthonous nutrients from the marine environment to coastal dune ecosystems through the release of various organic residues. This increased nutrient availability enhances the productivity of C. breviligulata, as indicated by significantly higher density and aboveground biomass on the sites occupied by the colony. However, species richness does not seem to be affected by the presence of grey seals. Thus, the benefits of daily fertilization appear to outweigh the mechanical damage and soil compaction occurring during winter. Par leurs diff & eacute;rentes activit & eacute;s, les pinnip & egrave;des alt & egrave;rent la dynamique des communaut & eacute;s v & eacute;g & eacute;tales des & eacute;cosyst & egrave;mes c & ocirc;tiers. Ainsi, l'utilisation des environnements c & ocirc;tiers en saison hivernale comme sites de reproduction par le phoque gris, en r & eacute;ponse & agrave; la disparition de la glace de mer, repr & eacute;sente une menace potentielle pour l'int & eacute;grit & eacute; & eacute;cologique des & eacute;cosyst & egrave;mes dunaires terrestres bordant le golfe du Saint-Laurent dans l'est du Canada. Dans cette & eacute;tude, nous caract & eacute;risons l'impact des phoques gris sur l'& eacute;cosyst & egrave;me dunaire de la r & eacute;serve & eacute;cologique de l'& Icirc;le-Brion en comparant la densit & eacute; et la biomasse du couvert v & eacute;g & eacute;tal et les propri & eacute;t & eacute;s physico-chimiques des substrats et des tissus de Calamagrostis breviligulata entre des sites occup & eacute;s par la colonie de phoques et des sites t & eacute;moins. Nos r & eacute;sultats indiquent que la colonie de phoques gris contribue au transfert de nutriments allochtones depuis l'environnement marin vers les & eacute;cosyst & egrave;mes dunaires c & ocirc;tiers par la lib & eacute;ration de divers r & eacute;sidus organiques. Cette fertilisation accrue, associ & eacute;e & agrave; la pr & eacute;sence de phoques gris, favorise la productivit & eacute; de C. breviligulata, comme en t & eacute;moignent la densit & eacute; et la biomasse a & eacute;rienne significativement plus & eacute;lev & eacute;es sur les sites occup & eacute;s par la colonie. Cependant, la richesse sp & eacute;cifique ne semble pas & ecirc;tre affect & eacute;e par la pr & eacute;sence des phoques gris. Ainsi, les b & eacute;n & eacute;fices d'une fertilisation quotidienne semblent sup & eacute;rieurs aux impacts m & eacute;caniques ressentis en hiver.
This seven-year study investigated the effects of forest structure and fragmentation on the Calypso orchid (Calypso bulbosa) (Orchidaceae). The species was found to prefer growing sites in the interior of the forest and near small openings. Proximity to clear-cuts and to openings had no effect on reproductive success. High canopy cover and shrub cover reduced the number of plants, while high shrub cover reduced the number of flowering plants. This in turn may affect the behaviour of bumblebees (Bombus spp.), the main pollinators of the Calypso orchid, and their ability to find and pollinate a plant. The number of flowering and pollinated plants was higher in large populations than in small ones. The long-term reproductive success of large populations, as measured by flower and fruit production, was more stable than that of small populations. Despite its status as a strictly protected species, the Calypso orchid is threatened by forest management, particularly in privately owned forests. Nature-friendly harvesting methods, such as selection harvesting and small-gap harvesting without soil preparation, may prove to be appropriate forest management practices in the species' sites. Cette & eacute;tude sur sept ans s'est int & eacute;ress & eacute;e aux effets de la structure foresti & egrave;re et de la fragmentation sur le calypso bulbeux (Calypso bulbosa) (Orchidaceae). L'esp & egrave;ce pr & eacute;f & egrave;re les sites au c oe ur des for & ecirc;ts et pr & egrave;s de petites ouvertures. La proximit & eacute; de coupes totales et d'ouvertures du couvert forestier n'avait pas d'effet sur le succ & egrave;s reproducteur. Un couvert & eacute;lev & eacute; d'arbres et d'arbustes diminue le nombre de plantes, tandis qu'un couvert & eacute;lev & eacute; d'arbustes diminue le nombre de plantes en floraison. Cela peut affecter le comportement des bourdons (Bombus spp.), les principaux pollinisateurs du calypso bulbeux, ainsi que leur capacit & eacute; & agrave; trouver et polliniser les plantes. Le nombre de plantes en floraison et pollinis & eacute;es & eacute;tait plus & eacute;lev & eacute; dans les grandes populations que dans les petites. Le succ & egrave;s reproducteur & agrave; long terme des grandes populations, tel que mesur & eacute; par la production de fleurs et de fruits, & eacute;tait plus stable que celui des petites populations. En d & eacute;pit de son statut d'esp & egrave;ce prot & eacute;g & eacute;e, le calypso bulbeux est menac & eacute; par l'am & eacute;nagement forestier, particuli & egrave;rement dans les for & ecirc;ts priv & eacute;es. Des m & eacute;thodes d'am & eacute;nagement moins intensives, telles que les coupes s & eacute;lectives et par petites trou & eacute;es sans pr & eacute;paration de sol, pourraient & ecirc;tre plus appropri & eacute;es dans les sites o & ugrave; l'esp & egrave;ce se trouve.
While biodiversity conservation in urban areas is a topic of great interest, few studies have focused on the role that urban conservation areas have for preserving biodiversity. Urban woodlands, which are patches of forest habitat confined within the city's boundaries, offer a promising approach to evaluate the importance of conservation areas within cities. Here, we examined the relationship between conservation status, forest structure and composition across 11 urban woodlands in Montr & eacute;al, Canada. We used field surveys to assess biodiversity, canopy cover, and structural complexity for urban woodlands with a conservation status and those without. We found that Montr & eacute;al's urban woodlands fostered similar levels of biodiversity regardless of conservation status. Similarly, all urban woodlands supported high proportions of native tree species despite differences in conservation status and associated management. Our results suggest that both conservation areas and non-status woodlands play an important role in safeguarding urban biodiversity. Woodlands with a conservation status, however, had higher canopy cover and vegetative complexity, but also contained higher average proportions of invasive trees, particularly Rhamnus cathartica (Common Buckthorn). While the high complexity in vegetation layers observed may provide habitat to native wildlife, these benefits may be limited by the high proportion of invasive trees. La conservation de la biodiversit & eacute; dans les zones urbaines est un sujet important, mais peu d'& eacute;tudes se sont pench & eacute;es sur le r & ocirc;le des aires prot & eacute;g & eacute;es urbaines & agrave; cet & eacute;gard. Les bois & eacute;s urbains, qui sont des parcelles foresti & egrave;res & agrave; l'int & eacute;rieur des limites d'une ville, offrent l'occasion d'& eacute;valuer l'importance des aires prot & eacute;g & eacute;es urbaines. Nous avons & eacute;tudi & eacute; la relation entre le statut de conservation et la structure et la composition foresti & egrave;res dans 11 bois & eacute;s urbains & agrave; Montr & eacute;al, Canada. Nous avons utilis & eacute; des relev & eacute;s terrain pour & eacute;valuer la biodiversit & eacute;, le couvert forestier et la complexit & eacute; structurelle de bois & eacute;s urbains avec ou sans statut de conservation. Nous avons trouv & eacute; que les bois & eacute;s urbains de Montr & eacute;al avaient des niveaux de biodiversit & eacute; similaires sans & eacute;gard & agrave; leur statut de conservation. De plus, tous les bois & eacute;s urbains avaient des proportions & eacute;lev & eacute;es d'esp & egrave;ces indig & egrave;nes, et ce, peu importe leur statut de conservation ou leur historique d'am & eacute;nagement. Nos r & eacute;sultats sugg & egrave;rent que les deux types de bois & eacute;s (prot & eacute;g & eacute;s ou pas) jouent un r & ocirc;le important dans la conservation de la biodiversit & eacute; urbaine. Toutefois, les bois & eacute;s avec statut de conservation avaient un couvert forestier plus important et une plus grande complexit & eacute; v & eacute;g & eacute;tale. Ils avaient aussi une proportion moyenne d'esp & egrave;ces arborescentes envahissantes plus & eacute;lev & eacute;e, particuli & egrave;rement Rhamnus cathartica (nerprun cathartique). Ainsi, alors que la complexit & eacute; v & eacute;g & eacute;tale & eacute;lev & eacute;e peut fournir des habitats & agrave; la faune indig & egrave;ne, ces b & eacute;n & eacute;fices pourraient & ecirc;tre limit & eacute;s par la proportion & eacute;lev & eacute;e d'esp & egrave;ces envahissantes.
Water use efficiency (WUE) is critical for understanding the carbon-water coupling of ecosystems, yet its response to extreme droughts remains debated. This study applied the CEVSA-ES model to simulate WUE across the Yangtze River Basin from 2020 to 2022, assessing the effects of extreme drought. The results reveal a significant 12.67% decrease in WUE during summer, while extreme and severe drought areas in autumn experienced an 11% increase in WUE. Seasonal WUE variations were linked to evapotranspiration (ET) and gross primary productivity (GPP): in summer, increased ET led to WUE decline, while reduced ET in areas affected by autumn drought resulted in WUE increase. In contrast, areas with moderate to light drought in autumn saw continued ET increase and WUE decline. These findings suggest that WUE responses to drought depend on drought duration and severity: WUE tends to decline in the early stages of drought and increase in later stages, with the transition timing influenced by drought severity. This study underscores the need to account for the spatiotemporal heterogeneity of drought and its complex regulatory mechanisms on WUE in predicting future climate change effects. L'efficacit & eacute; d'utilisation de l'eau (WUE) est importante pour comprendre le couplage carbone-eau des & eacute;cosyst & egrave;mes, mais sa r & eacute;ponse aux s & eacute;cheresses s & eacute;v & egrave;res demeure m & eacute;connue. Dans cette & eacute;tude, le mod & egrave;le CEVSA-ES a & eacute;t & eacute; utilis & eacute; pour simuler la WUE dans le bassin du fleuve Yangts & eacute; entre 2020 et 2022 afin d'& eacute;valuer les effets des s & eacute;cheresses s & eacute;v & egrave;res. Les r & eacute;sultats r & eacute;v & egrave;lent une diminution significative de 12,67% de la WUE en & eacute;t & eacute;, tandis que les zones affect & eacute;es par des s & eacute;cheresses s & eacute;v & egrave;res et extr & ecirc;mes en automne ont connu une augmentation de 11% de la WUE. Les variations saisonni & egrave;res de la WUE & eacute;taient influenc & eacute;es par l'& eacute;vapotranspiration (ET) et la productivit & eacute; primaire brute : en & eacute;t & eacute;, une augmentation de l'ET cause une diminution de la WUE, tandis qu'une diminution de l'ET dans les zones affect & eacute;es par des s & eacute;cheresses s & eacute;v & egrave;res en automne cause une augmentation de la WUE. Toutefois, les zones affect & eacute;es par des s & eacute;cheresses l & eacute;g & egrave;res ou mod & eacute;r & eacute;es en automne montrent une augmentation continue de l'ET ainsi qu'une diminution de la WUE. Ces r & eacute;sultats sugg & egrave;rent que la r & eacute;ponse de la WUE & agrave; la s & eacute;cheresse d & eacute;pend de la dur & eacute;e et de la s & eacute;v & eacute;rit & eacute; de la s & eacute;cheresse : la WUE tend & agrave; diminuer dans les premiers stades d'une s & eacute;cheresse, pour ensuite augmenter dans les stades plus avanc & eacute;s, plus ou moins tardivement selon la s & eacute;v & eacute;rit & eacute; de la s & eacute;cheresse. Cette & eacute;tude souligne la n & eacute;cessit & eacute; de tenir compte de l'h & eacute;t & eacute;rog & eacute;n & eacute;it & eacute; spatio-temporelle de la s & eacute;cheresse et de ses m & eacute;canismes r & eacute;gulatoires complexes sur la WUE afin de mieux pr & eacute;dire les effets des changements climatiques.
Vegetation diversity and the effect of fire on grassland communities in Odisha were evaluated, along with phenological behaviour in response to climatic factors. This study noted 3100 individuals from 63 grassland taxa under 12 families and 44 genera. Of these, 22 grass species and 11 non-grass species were found in burned grassland sites, while 13 grass species and 17 non-grass species were observed in unburned sites. About 81% of the examined individuals flowered in burned sites compared to 35% in unburned sites. The phytosociological investigation reveals that Imperata cylindrica, Cynodon dactylon, Mimosa pudica, and Dichanthium annulatum thrived and showed dominance after a severe fire. Phenological analyses revealed that flower initiation positively correlates with available nitrogen (r = 0.8, p < 0.01) and rainfall (r = 0.6, p < 0.01). However, a negative correlation was found between fruit senescence and soil moisture (r = -0.8, p < 0.01). Principal component analysis revealed that rainfall and available nitrogen are the main factors explaining phenological divergence in sampling sites. This case study on the interaction between phenological data and fire may help to conserve fire-resistant species and develop a conservation strategy for grassland taxa in fire-prone regions.
