Efectos hidrológicos de la conversión del bosque de niebla en el centro de Veracruz, México

Abstract

SUMMARYThe provision and regulation of water flows in catchments is probably the most important ecosystem service of cloud forests; however, its hydrological behavior and impacts associated with forest conversion remain very poorly understood. The present study aimed at evaluating the hydrological effects of land use change for a cloud forest region on volcanic soils in Veracruz, Mexico. For this, micrometeorological, ecophysiological and hydrological measurements combined with stable isotope data were used. The findings showed higher annual water yields in pasture, as well as young and mature Pinus patula pine plantations due to lower evapotranspiration rates as compared to mature and secondary cloud forests. Total annual and seasonal flows were found very similar in both cloud forests, suggesting catchment hydrological functioning can be restored within 20 years of natural regeneration. Conversely, the pasture catchment showed higher annual streamflow (10 %), however 50 % on average lower baseflow at the end of the dry season, associated probably with more gentle slopes in combination with lower soil infiltration capacity. Further, it was shown that the conversion of cloud forest to pasture can promote major increases in overland flow in response to maximum rainfall events, despite the high permeability of the volcanic soils characterizing this environment. The ultimate effect of P. patula reforestation at catchment scale is still unknown, though higher rainfall infiltration rates, compared to pasture, suggest a soil hydrological recovery in the short to medium term.Key words: land use change, evapotranspiration, streamflow, hydrograph separation, stable isotopes. RESUMENLa provisión y regulación de flujos de agua en cuencas es probablemente el servicio ecosistémico más importante de los bosques de niebla, sin embargo, su funcionamiento hidrológico y cómo éste es alterado por el cambio en el uso de suelo es aún muy poco entendido. Este estudio evaluó los efectos hidrológicos causados por la conversión del bosque mesófilo de montaña sobre suelo volcánico a otros tipos de vegetación en Veracruz, México. Para ello, se realizaron mediciones micrometeorológicas, ecofisiológicas e hidrológicas combinadas con información isotópica. Los resultados mostraron mayores rendimientos hídricos anuales en el pastizal y plantaciones de Pinus patula joven y maduro debido a menores tasas de evapotranspiración comparados con el bosque maduro y secundario. El caudal total anual y estacional fue similar en los bosques, sugiriendo que con 20 años de regeneración natural es posible restaurar la funcionalidad hidrológica de microcuencas. En contraste, la microcuenca de pastizal reportó un mayor caudal anual (10 %), pero flujos 50 % en promedio más bajos al final de la época de estiaje, asociado probablemente a una topografía más suave y una menor capacidad de infiltración. Aún en sustratos volcánicos altamente permeables, se observó que la conversión de bosque a pastizal puede conducir a incrementos importantes en los flujos superfici...

Interactions between payments for hydrologic services, landowner decisions, and ecohydrological consequences: synergies and disconnection in the cloud forest zone of central Veracruz, Mexico

“…Moreover, since rainfall interception by the two plantation forests was also lower, their overall ET was substantially less than that for mature and regenerating cloud forests (Muñoz-Villers et al 2015). Surprisingly, we also found that ET of the young and mature pine forests was similar to and less than that of pasture, respectively (Muñoz-Villers et al 2015). In addition to the relatively sparse canopy of mature P. patula trees, the relatively low ET in the mature P. patula stand was in part attributable to previous selective logging activities that had reduced stand basal area.…”

“…Consequently, for a mean annual precipitation (P) of ca. 3000 mm, water yield (P + CWI -ET) was much higher for pasture (2185 mm; with negligible CWI) than for mature cloud forests (1730 mm; with annual CWI = 45 mm) or regenerating cloud forests (1985 mm; with annual CWI = 38 mm) (Muñoz-Villers et al 2015). Despite higher annual water yield, baseflows from the pasture during the late dry season were 35% and 70% lower than flows from the mature and regenerating cloud forests, respectively; these differences were attributed to a combination of lower topsoil infiltration capacity, gentler topography, and lower soil and groundwater storage capacity in the pasture compared to the forested catchments (Muñoz-Villers and McDonnell 2013).…”

“…In Veracruz, Pinus patula, a species native to the region's highlands (above the cloud forest zone), is widely planted within the cloud forest zone as part of reforestation efforts. Our Veracruz study showed that a young 10-year-old P. patula plantation had almost 20% lower stand-level transpiration than nearby mature and 20-year-old regenerating cloud forest, whereas a mature, selectively harvested pine plantation had more than 60% lower stand-level transpiration than mature cloud forest (Alvarado-Barrientos 2013, Muñoz-Villers et al 2015). Moreover, since rainfall interception by the two plantation forests was also lower, their overall ET was substantially less than that for mature and regenerating cloud forests (Muñoz-Villers et al 2015).…”

“…Our Veracruz study showed that a young 10-year-old P. patula plantation had almost 20% lower stand-level transpiration than nearby mature and 20-year-old regenerating cloud forest, whereas a mature, selectively harvested pine plantation had more than 60% lower stand-level transpiration than mature cloud forest (Alvarado-Barrientos 2013, Muñoz-Villers et al 2015). Moreover, since rainfall interception by the two plantation forests was also lower, their overall ET was substantially less than that for mature and regenerating cloud forests (Muñoz-Villers et al 2015). Surprisingly, we also found that ET of the young and mature pine forests was similar to and less than that of pasture, respectively (Muñoz-Villers et al 2015).…”

“…We examined the ecohydrology of a mature and a regenerating cloud forest and the effects of cloud forest conversion to pasture and pine plantations on annual water yield and flow regulation in the upland region of the Los Gavilanes watershed in central Veracruz (see Muñoz-Villers et al 2015 for detailed site descriptions). We found that additional water inputs due to CWI were comparatively low (< 2% of 3180 mm yr -1 and 8% of dryseason rainfall of 640 mm), which was largely attributed to the relatively infrequent occurrence of dense fog and, especially, low wind speeds (Holwerda et al 2010, Alvarado-Barrientos et al 2014.…”