Mountain pine beetle infestation impacts: modeling water and energy budgets at the hill‐slope scale

Abstract

The mountain pine beetle (MPB) epidemic in western North America is generating growing concern associated with aesthetics, ecology, and forest and water resources. Given the substantial acreage of prematurely dying forests within Colorado and Wyoming (~two million acres in 2008), MPB infestations have the potential to significantly alter forest canopy, impacting several aspects of the local water and land‐energy cycle. Hydrologic processes that may be influenced include canopy interception of precipitation and radiation, snow accumulation, melt and sublimation, soil infiltration and evapotranspiration. To investigate the changing hydrologic and energy regimes associated with MPB infestations, we used an integrated hydrologic model coupled with a land surface model to incorporate physical processes related to energy at the land surface. This platform was used to model hillslope‐scale hydrology and land‐energy changes throughout the phases of MPB infestation through modification of the physical parameterisation that accounts for alteration of stomatal resistance and leaf area indices. Our results demonstrate that MPB infested watersheds will experience a decrease in evapotranspiration, an increase in snow accumulation accompanied by earlier and faster snowmelt and associated increases in runoff volume and timing. Impacts are similar to those projected under climate change, yet with a systematically higher snowpack. These results have implications for water resource management because of higher tendencies for flooding in the spring and drought in the summer. Copyright © 2011 John Wiley & Sons, Ltd.

Implementation of a Marauding Insect Module (MIM, version 1.0) in the Integrated BIosphere Simulator (IBIS, version 2.6b4) dynamic vegetation–land surface model

“…Many previous studies have represented insect damage in DVLSMs or less comprehensive climate-driven terrestrial models (Randerson et al, 1996;Krinner et al, 2005;Seidl et al, 2008;Wolf et al, 2008;Albani et al, 2010;Schäfer et al, 2010;Edburg et al, 2011;Medvigy et al, 2012;Mikkelson et al, 2013b;Chen et al, 2015). To our knowledge, however, our study is the first to assess, over daily to centennial timescales, the impacts from insect damage on vegetation dynamics and the carbon, energy, and water cycles in an integrated way (see Sect.…”

“…Based on the empirical relationships of McNaughton et al (1989), the ORganizing Carbon and Hydrology in Dynamic EcosystEms (ORCHIDEE) DVLSM accounts for background leaf consumption by herbivores (not limited to insects), but the realism of the resulting impact on simulated tree mortality has been questioned by the authors themselves (Krinner et al, 2005). The effects of prescribed mortality due to mountain pine beetle (MPB; Dendroctonus ponderosae Hopkins) outbreaks in western US on coupled carbon-nitrogen dynamics (Edburg et al, 2011) and water and energy exchanges (Mikkelson et al, 2013b) have been studied in the Community Land Model (CLM) DVLSM. Medvigy et al (2012) used the Ecosystem Demography version 2 (ED2) DVLSM to simulate the impacts of defoliation by the gypsy moth (Lymantria dispar Linnaeus) on vegetation coexistence and carbon dynamics in the eastern US.…”

“…Three of the four modelling studies (Wiedinmyer et al, 2012;Mikkelson et al, 2013b;Chen et al, 2015) indirectly forced the responses they obtained by directly reducing the total canopy conductance without accounting for the possible growth release of the surviving vegetation, while the fourth modelling study (included in the Mikkelson et al, 2013a, review) only computed the change in runoff and then assumed no change in soil moisture to estimate the change in evapotranspiration. The two satellite-based studies rest upon the highly parameterized MODIS evapotranspiration data set (Mu et al, 2011), which has not been developed and tested in the context of MPB-killed forests.…”

Albedo-induced radiative forcing from mountain pine beetle outbreaks in forests, south-central Rocky Mountains: magnitude, persistence, and relation to outbreak severity

“…Widespread tree mortality in mountain-pine-beetle-infested stands has been shown to result in earlier snowmelt, from increased canopy shortwave transmissions (Bewley et al, 2010;Pugh and Small, 2012), as well as increased stream flow, from a reduction in transpiration and canopy interception (Mikkelson et al, 2013). These changes could reduce water availability during the late growing season, exacerbating tree stress.…”

Rare Taxa Maintain Microbial Diversity and Contribute to Terrestrial Community Dynamics throughout Bark Beetle Infestation

“…In turn, terrestrial hydrologic and biogeochemical cycles are altered, as these trees succumb to beetle infestation (2). Decreased canopy cover, increased soil moisture (3,4) and temperature (5) along with changing carbon inputs associated with needle fall, the cessation of rhizodeposition, and the decay of large quantities of woody debris (6) are all examples of observed shifts in beetle-killed forests.…”