Precipitation interception in Australian tropical rainforests: II. Altitudinal gradients of cloud interception, stemflow, throughfall and interception

Abstract

Abstract:This article presents a comprehensive study of canopy interception in six rainforests in Australia's Wet Tropics for periods ranging between 2 and 3Ð5 years. Measurements of rainfall, throughfall, stemflow and cloud interception were made at sites characterized by different forest types, canopy structure, altitude, rainfall and exposure to prevailing winds. Throughfall at these sites ranged between 64 and 83% of total precipitation inputs, while stemflow ranged between 2 and 11%. At sites higher than 1000 m, cloud interception was found to contribute up to 66% of the monthly water input to the forest, more than twice the rainfall at these times. Over the entire study period, cloud interception accounted for between 4 and 30% of total precipitation inputs, and was related more to the exposure of sites to prevailing winds than to altitudinal differences alone.Over the duration of the study period, interception losses ranged between 22 and 29% of total water input (rainfall and cloud interception) at all sites except the highest altitude site on Bellenden Ker, where interception was 6% of total water input. This smaller interception loss was the result of extremely high rainfall, prolonged immersion in cloud and a sparser canopy. On a monthly basis, interception losses from the six sites varied between 10 and 88% of rainfall. All sites had much higher interception losses during the dry season than in the wet season because of the differences in storm size and rainfall intensity. The link between rainfall conditions and interception losses has important implications for how evaporative losses from forests may respond to altered rainfall regimes under climate change and/or large-scale atmospheric circulation variations such as El Niño.

Predicting organismal vulnerability to climate warming: roles of behaviour, physiology and adaptation

“…Moreover, humidity will drop, adding novel water stress to the woes of forest animals, especially those that are moisture-sensitive [179,194]. The increasing threat of forest disturbance or clearing [34] and declines in rainfall and cloud cover [124,195] potentially add another synergistic threat to closed forest species by opening up the canopy, adding the cascading threat of drying and fire [29], reducing thermal buffering and refugia, and facilitating invasion by the open-habitat species.…”

Modelling interception in coastal and montane rainforests in northern Queensland, Australia

“…de Lima, 1990;Holwerda, 2005;Sharon, 1980). The wind loss correction added between 1% and 3% to the measured values and the slope interception of horizontal rain added up to 8% more (McJannet et al, 2007b).…”

Climate change and its implications for Australia's freshwater fish

“…During the monsoonal summer months (December-March), air temperature, rainfall and floodplain inundation are at their peaks, whereas stable baseflows extend through the dry season (April-November), maintained by rainfall-recharged groundwater and cloud capture in upland rainforests (McJannet et al 2007). The Wet Tropics region hosts a highly diverse and endemic freshwater fish fauna (,107 species, ,50% of Australia's freshwater fish biodiversity), including representatives from 37 families .…”