The recurring use of fire in the Guinean savanna underscores the need to identify the local climatic parameters that predict fire behavior. This study was conducted in 2013-2016, with three experimental fire periods (early, mid and late season) each year. The objective was to identify, among the climatic parameters of the year before the fire (PCAs), during the month of the fire (PCMs), and during the fire (PCDs), those that best predict fuel and fire characteristics. Mixed-effects multiple regressions and model selection showed that PCAs do not influence fuel load and fire intensity. Among the PCMs, the number of days between the last rain > 1 mm and the fire determines fuel humidity. Moreover, the more it rains during the month of the fire and/or in the 10 days before, the lower the intensity. Among the PCDs, air humidity is the key factor: the lower it is, the faster the fire spreads and the more intense it is. Only PCMs determine fire intensity. This study highlights that rainfall occurring shortly before a fire determines fire intensity through its effect on litter moisture content. These results open up new perspectives for modeling the spread of fires in the Guinean savanna.
This study analyzed land use and land cover changes in the San Nicol & aacute;s-Cuitzmala watershed, Mexico, from 2017 to 2025 using Sentinel-2 imagery and InVEST software. Results revealed a significant landscape transformation characterized by the loss of approximately 30,000 hectares of tropical dry forest (TDF), which was primarily converted into grassland. While the Total Ecosystem Services Value (TESV) showed a slight numerical increase, rising from $3.642 billion to $3.721 billion, this shift masks critical ecological trade-offs. The expansion of grasslands increased pollination values but resulted in a 4.00% reduction in total carbon stocks, decreasing from 82.45 Tg C to 79.15 Tg C. Even within the Chamela-Cuixmala Biosphere Reserve, TDF conversion was evident along its northern boundary. These findings suggest that while certain economic valuations may rise, the loss of TDF represents a net decline in vital regulating services, such as carbon sequestration and biodiversity support. The study emphasizes the urgent need for integrated land management and robust conservation strategies to protect remaining dry forests from anthropogenic pressures and ensure the long-term sustainability of the watershed's essential ecosystem functions. Les changements d'utilisation et d'occupation des terres ont & eacute;t & eacute; analys & eacute;s dans le bassin versant de San Nicol & aacute;s-Cuitzmala (Mexique) entre 2017 et 2025 & agrave; l'aide d'images Sentinel-2 et du logiciel InVEST. Les r & eacute;sultats ont r & eacute;v & eacute;l & eacute; une transformation significative du paysage caract & eacute;ris & eacute;e par la perte d'environ 30 000 hectares de for & ecirc;ts tropicales s & egrave;ches, la plupart converties en prairies. Alors que la valeur totale de services & eacute;cosyst & eacute;miques a l & eacute;g & egrave;rement augment & eacute; de 3,642 milliards de dollars & agrave; 3,721 milliards de dollars, ce changement masque des compromis & eacute;cologiques majeurs. L'expansion des prairies a augment & eacute; la valeur des services de pollinisation mais a caus & eacute; une r & eacute;duction de 4,00 % des stocks totaux de carbone (de 82,45 Tg & agrave; 79,15 Tg). La conversion des for & ecirc;ts tropicales s & egrave;ches a m & ecirc;me & eacute;t & eacute; not & eacute;e & agrave; la limite nord de la r & eacute;serve de biosph & egrave;re de Chamela-Cuixmala. Ces r & eacute;sultats sugg & egrave;rent que m & ecirc;me si la valeur & eacute;conomique de certains services augmente, la perte de for & ecirc;ts tropicales s & egrave;ches repr & eacute;sente un d & eacute;clin net de services de r & eacute;gulation essentiels comme le stockage du carbone et le soutien & agrave; la biodiversit & eacute;. L'& eacute;tude souligne le besoin urgent de gestion int & eacute;gr & eacute;e des terres et de strat & eacute;gies de conservation robustes afin de prot & eacute;ger les for & ecirc;ts tropicales s & egrave;ches restantes contre les pressions anthropiques et d'assurer la durabilit & eacute; des fonctions & eacute;cosyst & eacute;miques essentielles du bassin versant.
The recurring use of fire in the Guinean savanna underscores the need to identify the local climatic parameters that predict fire behavior. This study was conducted in 2013–2016, with three experimental fire periods (early, mid and late season) each year. The objective was to identify, among the climatic parameters of the year before the fire (PCAs), during the month of the fire (PCMs), and during the fire (PCDs), those that best predict fuel and fire characteristics. Mixed-effects multiple regressions and model selection showed that PCAs do not influence fuel load and fire intensity. Among the PCMs, the number of days between the last rain > 1 mm and the fire determines fuel humidity. Moreover, the more it rains during the month of the fire and/or in the 10 days before, the lower the intensity. Among the PCDs, air humidity is the key factor: the lower it is, the faster the fire spreads and the more intense it is. Only PCMs determine fire intensity. This study highlights that rainfall occurring shortly before a fire determines fire intensity through its effect on litter moisture content. These results open up new perspectives for modeling the spread of fires in the Guinean savanna.
Climate change poses significant risks to endemic mountain butterflies, particularly those in isolated arid refugia. We assessed the extinction risk of Satyrium jebelia, Egypt's only endemic butterfly, found in high-altitude habitats (1,800-2,400 m) in the Saint Catherine Protectorate, Sinai Peninsula. Using Maximum Entropy (MaxEnt) modeling with 12 georeferenced occurrence records and five bioclimatic variables, we projected habitat suitability under two climate scenarios (RCP 2.6 and RCP 8.5) for 2050 and 2070. Our model achieved an AUC of 0.99, identifying the mean temperature of the coldest quarter (52.8% contribution) and precipitation of the driest quarter (39.9% contribution) as key factors in species distribution. Currently, S. jebelia occupies less than 5% of the Sinai Peninsula, with suitable habitat highly fragmented. Climate projections indicate a 50% habitat loss by 2050 and near-total extinction by 2070 under high-emission scenarios (RCP 8.5). Even under moderate warming (RCP 2.6), significant contractions are expected, with viable habitats limited to a few refugial areas. Given a projected 80% population decline over three genera, we recommend evaluating S. jebelia for Critically Endangered status on the IUCN Red List and implementing urgent conservation measures, including ex-situ breeding and population monitoring. Le changement climatique entra & icirc;ne des risques importants pour les esp & egrave;ces de papillons end & eacute;miques des montagnes, particuli & egrave;rement dans les refuges arides isol & eacute;s. Nous avons & eacute;valu & eacute; le risque d'extinction de Satyrium jebelia, le seul papillon end & eacute;mique de l'& Eacute;gypte, trouv & eacute; aux hautes altitudes (1800-2400m) dans le protectorat de Sainte-Catherine de la p & eacute;ninsule du Sina & iuml;. En utilisant la mod & eacute;lisation par entropie maximale (MaxEnt) bas & eacute;e sur 12 occurrences g & eacute;or & eacute;f & eacute;renc & eacute;es et cinq variables bioclimatiques, nous avons projet & eacute; la qualit & eacute; d'habitat sous deux sc & eacute;narios climatiques (RCP 2.6 et RCP 8.5) aux horizons 2050 et 2070. Notre mod & egrave;le, dont l'aire sous la courbe est de 0,99, a identifi & eacute; la temp & eacute;rature moyenne du trimestre le plus froid (contribution = 52,8%) et les pr & eacute;cipitations du trimestre le plus sec (39,9%) comme & eacute;tant les principaux facteurs influen & ccedil;ant la r & eacute;partition de l'esp & egrave;ce. Pr & eacute;sentement, S. jebelia occupe moins de 5% de la p & eacute;ninsule du Sina & iuml; et les habitats ad & eacute;quats sont tr & egrave;s fragment & eacute;s. Les projections climatiques indiquent une perte de 50% des habitats d'ici 2050 et la quasi-extinction de l'esp & egrave;ce d'ici 2070 sous les sc & eacute;narios d'& eacute;missions & eacute;lev & eacute;es (RCP 8.5). M & ecirc;me un r & eacute;chauffement climatique mod & eacute;r & eacute; (RCP 2.6) entra & icirc;nerait des contractions majeures, les habitats viables se retrouvant limit & eacute;s & agrave; quelques refuges. Consid & eacute;rant un d & eacute;clin projet & eacute; de 80% de la population au cours des trois prochaines g & eacute;n & eacute;rations, nous recommandons d'& eacute;valuer la possibilit & eacute; d'ajouter S. jebelia aux esp & egrave;ces en danger critique de la Liste rouge de l'UICN et de mettre en oe uvre des mesures de conservation urgentes incluant la reproduction ex-situ et le suivi des populations.
The Indian Himalayan region harbours a diverse assemblage of conifer species distributed across contrasting Inner (monsoon rain-shadow) and Outer (monsoon-exposed) zones. Understanding their climatic niches is essential for explaining distribution patterns, adaptive capacity, and vulnerability to climate change. We quantified niche dynamics of 11 Himalayan conifers by assessing climatic niche overlap (Schoener's D), hypervolume-based niche breadth, and environmental variable contributions across the two zones. Niche overlap between Inner and Outer Himalayan populations was generally low (D = 0.01-0.21), with Cedrus deodara showing the highest overlap and Cupressus torulosa exhibiting near-complete divergence. Hypervolume analysis revealed broader niches in the Outer Himalaya, suggesting greater environmental heterogeneity and wider climatic tolerance, whereas species in the Inner Himalaya occupied narrower and more specialized climatic spaces. Principal Component Analysis identified temperature variables (bio1, bio3, bio5, bio7, bio10) and precipitation variables (bio12, bio16, bio17, bio18) as the main drivers of niche differentiation. However, niche equivalency and similarity tests indicated that observed differences were not greater than expected by chance, suggesting overall climatic niche conservatism. These results indicate that Himalayan conifer distributions are shaped by the interaction of temperature and monsoon-driven precipitation, with regional climatic variability influencing niche breadth. La r & eacute;gion himalayenne de l'Inde abrite un ensemble diversifi & eacute; d'esp & egrave;ces de conif & egrave;res r & eacute;parties entre deux zones contrast & eacute;es : l'int & eacute;rieur (& agrave; l'abri de la mousson) et l'ext & eacute;rieur (expos & eacute; & agrave; la mousson). Comprendre leurs niches climatiques est essentiel pour expliquer leurs aires de r & eacute;partition, leur capacit & eacute; d'adaptation et leur vuln & eacute;rabilit & eacute; face aux changements climatiques. Nous avons quantifi & eacute; la dynamique des niches de 11 esp & egrave;ces de conif & egrave;res himalayens en & eacute;valuant le chevauchement des niches climatiques (indice D de Schoener), l'amplitude des niches fond & eacute;e sur les hypervolumes, ainsi que la contribution des variables environnementales dans les deux zones. Le chevauchement de niche entre les populations de l'Himalaya int & eacute;rieur et ext & eacute;rieur est g & eacute;n & eacute;ralement faible (D = 0,01 & agrave; 0,21). Cedrus deodara pr & eacute;sente le plus fort chevauchement, tandis que Cupressus torulosa montre une divergence presque compl & egrave;te. L'analyse par hypervolumes r & eacute;v & egrave;le des niches plus vastes dans l'Himalaya ext & eacute;rieur, ce qui sugg & egrave;re une plus grande h & eacute;t & eacute;rog & eacute;n & eacute;it & eacute; environnementale et une tol & eacute;rance climatique plus & eacute;tendue. & Agrave; l'inverse, dans l'Himalaya int & eacute;rieur, les esp & egrave;ces occupent des espaces climatiques plus restreints et davantage sp & eacute;cialis & eacute;s. L'analyse en composantes principales a identifi & eacute; les variables de temp & eacute;rature (bio1, bio3, bio5, bio7, bio10) et de pr & eacute;cipitations (bio12, bio16, bio17, bio18) comme les principaux d & eacute;terminants de la diff & eacute;renciation des niches. Toutefois, les tests d'& eacute;quivalence et de similarit & eacute; des niches ont indiqu & eacute; que les diff & eacute;rences observ & eacute;es n'& eacute;taient pas sup & eacute;rieures & agrave; celles attendues au hasard, ce qui sugg & egrave;re un conservatisme des niches climatiques. Ces r & eacute;sultats indiquent que la distribution des conif & egrave;res himalayens est fa & ccedil;onn & eacute;e par l'interaction entre la temp & eacute;rature et les pr & eacute;cipitations li & eacute;es & agrave; la mousson, tandis que la variabilit & eacute; climatique r & eacute;gionale influence l'amplitude des niches & eacute;cologiques.
