Rainfall partitioning and cloud water interception in native forest and invaded forest in Hawai'i Volcanoes National Park

Abstract

Abstract:In many Hawaiian forests, including cloud forests, native plant communities are being displaced by invasive tree species, possibly affecting rainfall partitioning and direct harvesting of cloud droplets by vegetation. In this study, the hydrological impacts of invasive species are examined, using measurements of rainfall (RF), throughfall (TF) and stemflow (SF), and estimation of wet-canopy evaporation and cloud water interception (CWI) by the canopy water balance approach in both native Metrosideros polymorpha-dominated and invaded, Psidium cattleianum-dominated forests within Hawai'i Volcanoes National Park (HAVO). Canopy water storage capacity was found to be more than twice as great at the native site (1Ð86 mm) compared to the invaded site (0Ð85 mm). Annual RF, CWI, TF and SF were 3233, 1188, 3700 and 261 mm, respectively, for the native site; and 3735, 734, 3033 and 1091 mm, respectively, for the invaded site. Net RF (TF C SF) was 123 and 110% of RF, respectively, at the two sites. Annual evaporation of water from the wet canopy was also greater at the native site (464 mm) than at the invaded site (347 mm). Low canopy water storage capacity and the exceptionally high SF total at the invaded site are related to morphological characteristics and high stem density of the invasive P. cattleianum tree, which favour efficient transport of intercepted water to the ground via the stems. Despite its more peripheral location near the edge of the orographic cloud, CWI at the native site was higher. The characteristics of the native M. polymorpha tree may facilitate more effective harvesting of cloud water droplets, enhancing CWI at the site. Species invasion results in a lower proportion of RF reaching the forest floor (110 vs 123%) and becoming available for groundwater recharge, suggesting that invasion by P. cattleianum may have significant negative effects on Hawai'i's aquatic ecosystems and water resources.

Climate change and conservation of endemic amphidromous fishes in Hawaiian streams

“…Long-term patterns of decline in part correspond to shifts in the dominant plant species in high-elevation forests (Takahashi et al 2011). Comparisons between native forests and those dominated by invasive strawberry guava (Psidium cattleianum), for example, demonstrated that guava-dominated forests receive significantly less cloud water.…”

“…Comparisons between native forests and those dominated by invasive strawberry guava (Psidium cattleianum), for example, demonstrated that guava-dominated forests receive significantly less cloud water. Guavadominated forests also have half the canopy water storage capacity of native forests (Takahashi et al 2011). All of these conditions can result in lower groundwater recharge and less stream channel discharge (Takahashi et al 2011).…”

“…Guavadominated forests also have half the canopy water storage capacity of native forests (Takahashi et al 2011). All of these conditions can result in lower groundwater recharge and less stream channel discharge (Takahashi et al 2011). …”

Spatially distributed groundwater recharge estimated using a water-budget model for the Island of Maui, Hawai`i, 1978–2007

“…Canopy capacity was set at 0.05 inches, the mean of the average values reported for six forested sites in Hawai'i (DeLay, 2005, p. 42; Takahashi andothers, 2011, Safeeq andFares, 2014). Trunk-storage capacity was set at 0.01 inches, the mean of the values reported for four forest sites in Hawai'i (DeLay, 2005, p. 42; Safeeq and Fares, 2014).…”

Managing conflict over biological control

“…It also included recent analyses of remote sensing and other studies of the strawberry guava invasion that strongly documented negative ecological effects of the weed (Asner et al, 2008;Zimmerman et al, 2008;Takahashi et al, 2011), an economic analysis of conventional control methods, and a cultural impact assessment (State of Hawaii, 2010). This document incorporated the many statewide consultations over the preceding two years, including inputs from public meetings.…”