Spatial and temporal variability of guinea grass (Megathyrsus maximus) fuel loads and moisture on Oahu, Hawaii

Abstract

Frequent wildfires in tropical landscapes dominated by non-native invasive grasses threaten surrounding ecosystems and developed areas. To better manage fire, accurate estimates of the spatial and temporal variability in fuels are urgently needed. We quantified the spatial variability in live and dead fine fuel loads and moistures at four guinea grass (Megathyrsus maximus) dominated sites. To assess temporal variability, we sampled these four sites each summer for 3 years (2008–2010) and also sampled fuel loads, moistures and weather variables biweekly at three sites for 1 year. Live and dead fine fuel loads ranged spatially from 0.85 to 8.66 and 1.50 to 25.74Mgha–1 respectively, and did not vary by site or year. Biweekly live and dead fuel moistures varied by 250 and 54% respectively, and were closely correlated (P<0.05) with soil moisture, relative humidity, air temperature and precipitation. Overall, fine fuels and moistures exhibited tremendous variability, highlighting the importance of real-time, site-specific data for fire prevention and management. However, tight correlations with commonly quantified weather variables demonstrates the capacity to accurately predict fuel variables across large landscapes to better inform management and research on fire potential in guinea grass ecosystems in Hawaii and throughout the tropics.

Analysis of Bushfires Spatial and Temporal Variability in Guinea

“…A better understanding of the spatial and temporal variability in fuel loads and moistures associated with invasive grasses is, therefore, integral to fire prevention and management in these ecosystems [18]. Considering their impact on the environment, fire issues become a challenge for the conservation of natural resources, the fight against climate change and the improvement of the living environment.…”

The Contemporary Scale and Context of Wildfire in Hawai‘i

“…comm.) be cause of very high fi ne fuel loads (Beavers et al 1999, Castillo et al 2003, Ellsworth et al 2013. Furthermore, Hawai ' i ' s rug ged ter rain provi des few op tions for safe in gress / egress, of ten lim it ing sup pres sion ef forts at a fi re ' s lead ing edge to wa ter drops from he li cop ters, which sub stan tially in creases sup pres sion costs.…”

“…Our un der standing of wild fi re dy nam ics in Hawai ' i, and on trop i cal is lands more gen er al ly, is lim ited rela tive to the de vel op ment of fi re re search and man age ment knowl edge in con ti nen tal ecosys tems. For in stance, established tools for fi re pre dic tion and op er a tional re sponse, such as stan dard fuel and fi re spread mod els and the National Fire Danger Rating System, have un cer tain ap pli ca bil ity in Hawai ' i due to high en vi ron men tal var i abil i ty, com pletely novel fuel types, lim ited weather da ta, and lim ited op por tu ni ties to con duct ex per i men tal burns (Beavers et al 1999, Fujioka et al 2000, Benoit et al 2009, Weise et al 2010, Ellsworth et al 2013. Given the existing knowl edge gaps and lim ited re sources for pro jects, it is im per a tive that ef forts to fur ther de velop fi re sci ence in Hawai ' i ex plic itly meet the needs of and be made ac ces si ble to on -the -ground prac ti tion ers.…”

PROPIEDADES FÍSICO-MECÁNICAS DE LA MADERA DE URACO(Ocotea brevipetiolata van der Werff),MUNICIPIO DE SIBUNDOY, PUTUMAYO

“…Praderas con especies del genero Brachiaria pueden incrementar la capacidad de carga a 3,5 UGG [14,20] y en M. maximus hasta 3,2 UGG en periodo de lluvias y 1,1 en la estación seca [19], esta condición permite liberar áreas productivas para la agricultura y por ende disminuir la presión sobre ecosistemas naturales evitando la transformación del paisaje a praderas.…”

“…Otro aspecto tenido en cuenta en el mejoramiento, es la resistencia a la sequía y/o inundación y persistencia en suelos pobres. Investigaciones realizadas con B. mutica muestran que la especie tiene un sistema radical que maximiza la extracción de humedad a lo largo del perfil del suelo, lo que permite mantener la turgencia y la actividad fotosintética hasta agotar la humedad disponible [19,20,21].…”