Natural vegetation in arid and semi-arid environments of Northwestern Mexico has been subject to transformation due to extensive and intensive human occupation related mostly to primary activities. Keystone habitats such as riparian ecosystems are extremely sensitive to land use changes that occur in their surrounding landscape. In this study, we developed remote sensing-based land cover classifications and post-classification fragmentation analysis, by using data from Landsat’s moderate resolution sensors Thematic Mapper and Operational Land Imager (TM and OLI) to assess land use changes and the shift in landscape configuration in a riparian corridor of a dynamic watershed in central Sonora during the last 30 years. In addition, we derived a high spatial resolution classification (using PlanetScope-PS2 imagery) to assess the “recent state” of the riparian corridor. According to our results, riparian vegetation has increased by 40%, although only 9% of this coverage corresponds to obligate riparian species. Scrub area shows a declining trend, with a loss of more than 17,000 ha due to the expansion of mesquite and buffelgrass-dominated areas. The use of moderate resolution Landsat data was essential to register changes in vegetation cover through time, however, higher resolution PlanetScope data were fundamental for the detection of limited aerial extent classes such as obligate riparian vegetation. The unregulated development of anthropogenic activities is suggested to be the main driver of land cover change processes for arid ecosystems in this region. These results highlight the urgent need for alternative management and restoration projects in an area where there is almost a total lack of protection regulations or conservation efforts.
La composición y estructura de la vegetación ribereña de los ríos Sonora y Bacanuchi en Sonora fueron determinadas después de la ocurrencia de eventos climáticos extraordinarios. Se registró el diámetro, la altura, el área basal y la cobertura por especie en 232 sitios (50 x 20 m). Se registraron 77 especies perteneciendo a 28 familias y 61 géneros con un total de 11,344 individuos (ind) muestreados. Para especies arbóreas la densidad promedio fue de 80 ind ha-1 área basal promedio de 0.07 m2; cobertura aérea promedio 131.3 m2 y altura promedio de 6.9 m. Mientras que las especies con mayor valor de importancia relativa fueron álamo, mezquite y sauce con el 39.3, 17.2 y 13.3%, respectivamente. En lo relativo con las especies arbustivas el batamote y la jécota fueron las especies que obtuvieron mayores valores de importancia relativa con el 43.02 y 20.33%. Se evaluó el número de individuos muertos atribuible a los eventos climatológicos resultando el 18.4% del total muestreado. Los resultados de este estudio pueden servir como referencia para futuros trabajos a realizarse en el río Sonora y otros ríos de la región, ya que ha contribuido al conocimiento de la vegetación y flora, en general y en particular la estructura y composición florística de estos ecosistemas ribereños.
Diversas actividades humanas como la ganadería han transformado gran parte de la superficie terrestre, provocando cambios en todos los ecosistemas, incluyendo las áreas prioritarias para la conservación, como el caso de Sierra Libre, donde la principal actividad económica es la ganadería extensiva, cuyas acciones de manejo ocasionan la sustitución de vegetación natural por la introducción de pastos exóticos como el zacate buffel. El objetivo para este trabajo fue: generar clasificaciones de cobertura/uso de suelo mediante percepción remota y cuantificar el cambio en la cobertura entre 1993 y 2011, con el fin de evaluar las modificaciones del paisaje asociadas a la introducción y permanencia de praderas de buffel en Sierra Libre. Se observó intercambio entre pastizales Inducidos y Mezquital, resultando en una ganancia neta de 4,049 ha de pastizales; sin embargo, el intercambio entre Matorral Subtropical y Pastizales resulto en una pérdida neta de 3,313 ha de los mismos, entre 1993 y 2011. Contrario a lo esperado, los pastizales inducidos, no aumentaron considerable en extensión entre 1993 y 2011. Esto sugiere la necesidad de contabilizar las áreas cubiertas por zacate buffel y replantear las teorías relacionadas a la utilidad de especies exóticas para forraje en la zona central de Sonora.
Wheat cultivation makes an important contribution to human nutrition. Trehalose synthesis plays a role in the tolerance to drought stress. A bifunctional TPS-TPP enzyme gene from yeast was used to obtain transgenic wheat plants to increase trehalose synthesis. Mature wheat embryos were transformed using pGreen rd29A::TPS1-TPS2 or pGreen 35S::TPS1-TPS2 constructs. The transgene presence in mature leaves of T3 plants was confirmed by sequencing a PCR fragment of the inserted transgene. Transgenic and NT plants were submitted to drought stress for eight days. Transformed wheat lines retained a higher relative water content than NT plants during drought stress, and the Rubisco activity was unaffected. Plants transformed with the 35S construct showed a lower photosynthetic rate and lower fructose 1–6-bisphosphatase (FBPase) activity during drought, suggesting that constitutive trehalose and sucrose synthesis caused a reduced ribulose 1,5-bisphosphate (RuBP) regeneration. Lines transformed with the rd29A promoter showed a higher photosynthetic rate after eight days of drought, as the RuBP regeneration was unaffected. Transgenic wheat plants had higher biomass and grain weight than NT plants after drought. These results suggest that trehalose synthesis improves photosynthesis during stress and induces changes in the activity of some Calvin-cycle enzymes, reflected in plant metabolism and growth.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.