Assessing effects of native forest restoration on soil moisture dynamics and potential aquifer recharge, Auwahi, Maui

Ecohydrology
By: , and 

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Abstract

Understanding the role of soils in regulating water flow through the unsaturated zone is critical in assessing the influence of vegetation on soil moisture dynamics and aquifer recharge. Because of fire, introduced ungulates and landscape-level invasion of non-native grasses, less than 10% of original dry forest (~730 mm precipitation annually) still exists on leeward Haleakalā, Maui, Hawaiian Islands. Native dry forest restoration at Auwahi has demonstrated the potential for dramatic revegetation, allowing a unique experimental comparison of hydrologic function between tracts of restored forest and adjacent grasslands. We hypothesized that even relatively recent forest restoration can assist in the recovery of impaired hydrologic function, potentially increasing aquifer recharge. To compare restored forest and grassland sites, we experimentally irrigated and measured soil moisture and temperature with subsurface instrumentation at four locations within the reforested area and four within the grassland, each with a 2·5 × 2·5-m plot. Compared with grassland areas, water in reforested sites moved to depth faster with larger magnitude changes in water content. The median first arrival velocity of water was greater by a factor of about 13 in the reforested sites compared with the grassland sites. This rapid transport of water to depths of 1 m or greater suggests increased potential aquifer recharge. Improved characterization of how vegetation and soils influence recharge is crucial for understanding the long-term impacts of forest restoration on aquifer recharge and water resources, especially in moisture-limited regions.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Assessing effects of native forest restoration on soil moisture dynamics and potential aquifer recharge, Auwahi, Maui
Series title Ecohydrology
DOI 10.1002/eco.1469
Volume 7
Issue 5
Year Published 2014
Language English
Publisher Wiley
Contributing office(s) National Research Program - Western Branch
Description 15 p.
First page 1437
Last page 1451
Country United States
State Hawaii
Other Geospatial Haleakalā, Maui
Online Only (Y/N) N
Additional Online Files (Y/N) N