Transformative ecosystem change and ecohydrology: ushering in a new era for watershed management

Abstract

As a result of human activities, forests and rangelands across the globe have undergone dramatic changes that have fundamentally altered ecosystem processes. Examples of these kinds of transformational changes include increasingly hot and extensive forest fires, die-off over vast areas of forest from insect infestations, large-scale encroachment of rangelands by woody plants and non-native invasive plants, and desertification. These changes have accelerated in pace, scale and magnitude in recent decades and have the potential to alter water, energy, and biogeochemical cycles in important but not fully understood ways. The related disciplines of ecohydrology and watershed management are being shaped and transformed by the need to understand the ecohydrological consequences of transformative landscape change as well as the need to mitigate and manage for these changes.

Ecohydrology: Processes and Implications for Rangelands

“…During the past quarter century, considerable research has been focused on understanding the ecohydrological implications of this conversion (Huxman et al 2005;Wilcox et al 2006). It has generally been found (though not always-see Moran et al (2010)) that infiltration rates are higher beneath shrub canopies than in intercanopy areas (Lyford and Qashu 1969;Seyfried 1991;Bergkamp 1998b;Schlesinger et al 1999;Wilcox 2002;D'Odorico et al 2007;Wilcox et al 2008;Pierson et al 2010;Daryanto et al 2013;Eldridge et al 2013), primarily owing to the accumulation of organic matter under shrubs, root activity (Joffre and Rambal 1993;Martinez-Meza and Whitford 1996;Jackson et al 2000), and soil disturbance by fauna (see "Influence of Fauna" section). In some situations the chemical composition of the litter may cause water repellency (hydrophobicity), which reduces the infiltration capacity of soils beneath the canopy, at least in the short term (Doerr et al 2000).…”

Forest ecohydrological research in the 21st century: what are the critical needs?

“…Changes in hydroperiod (Ford and Brooks, 2002;Ernst and Brooks, 2003) and sea level rise (Ross et al, 1994) will have significant direct impacts on hydrological processes in forested wetlands (Amatya et al, 2006). Most importantly, climate change and variability have the potential to interact with land use change and alter disturbance regimes to exacerbate the direct impacts on water quality and quantity (Wilcox, 2010). For example, warming and drought in North America has resulted in widespread mountain pine beetle infestations throughout the western United States and Canada (Kurz et al, 2008), and warming has modified snow regimes (Barnett et al, 2008) and has increased the frequency and severity of large wildfires (Westerling et al, 2006).…”

Training hydrologists to be ecohydrologists and play a leading role in environmental problem solving

“…The environmental management implications of this sphere of ecohydrology are large, both because anthropogenic-driven land use change has altered nearly half of Earth's surface and much of the land conversion is related to food provision for a burgeoning human population (Vitousek et al, 1997;Foley et al, 2005). Changes in the composition and configuration of vegetation alter the hydrological cycle from plot to continental scales (Colman, 1953;Likens et al, 1977;Eshleman, 2004) and set in motion a cascade of related impacts, some intended and others not (Wilcox, 2010). In addition to working to better understand process-level changes brought by land use change, ecohydrologists are also working to develop and improve modeling tools to assess impacts over entire catchments (Fohrer et al, 2005;van Griensven et al, 2006).…”