Interactions Among Fuel Management, Species Composition, Bark Beetles, and Climate Change and the Potential Effects on Forests of the Lake Tahoe Basin

Abstract

Climate-driven increases in wildfires, drought conditions, and insect outbreaks are critical threats to forest carbon stores. In particular, bark beetles are important disturbance agents although their longterm interactions with future climate change are poorly understood. Droughts and the associated moisture deficit contribute to the onset of bark beetle outbreaks although outbreak extent and severity is dependent upon the density of host trees, wildfire, and forest management. Our objective was to estimate the effects of climate change and bark beetle outbreaks on ecosystem carbon dynamics over the next century in a western US forest. Specifically, we hypothesized that (a) bark beetle outbreaks under climate change would reduce net ecosystem carbon balance (NECB) and increase

Can Land Management Buffer Impacts of Climate Changes and Altered Fire Regimes on Ecosystems of the Southwestern United States?

“…Tipping points are critical thresholds at which even small perturbations radically and persistently reorganize system patterns or processes [114,115]. This fundamental reorganization of ecosystems aligns with previous modeling that incorporates climate change, fire, and vegetation interactions in temperate forests [57,116], as well as conceptual models that identify shrublands as an alternative, stable state in dry conifer-shrub ecosystems catalyzed by interacting anthropogenic stressors (e.g., climate changes and altered fire regimes) that push systems past a tipping point [117,118]. Modeled forest to shrubland transformations are aligned with field studies; for example, a recent study in the Jemez Mountains attributes the presence of Gambel oak shrubfields to high-severity wildfire disturbances [118].…”

Tree defence and bark beetles in a drying world: carbon partitioning, functioning and modelling

“…tree evapotranspiration relative to potential evapotranspiration (Temperli et al ., ). Other approaches to account for drought stress include a tree‐specific threshold relating water demand to water supply (Jönsson et al ., ), or a climatic drought index (Scheller et al ., ). We found only one model (3%) relating defence capacity directly to a tree's physiological status, which simulated susceptibility as a function of the NSC reserves in individual host trees (Seidl & Rammer, ).…”

Wildland Fire, Forest Dynamics, and Their Interactions

“…Tipping points are critical thresholds at which even small perturbations radically and persistently reorganize system patterns or processes [114,115]. This fundamental reorganization of ecosystems aligns with previous modeling that incorporates climate change, fire, and vegetation interactions in temperate forests [57,116], as well as conceptual models that identify shrublands as an alternative, stable state in dry conifer-shrub ecosystems catalyzed by interacting anthropogenic stressors (e.g., climate changes and altered fire regimes) that push systems past a tipping point [117,118]. Modeled forest to shrubland transformations are aligned with field studies; for example, a recent study in the Jemez Mountains attributes the presence of Gambel oak shrubfields to high-severity wildfire disturbances [118].…”

“…They have the strength of being able to use modelling to combine disparate sources of data to predict attributes in a parsimonious manner [23,27,[116][117][118]. Advantages include the ability respond to dynamic changes (such as incorporating observations [119]) as well as being able to spatially quantify uncertainty around attribute values.…”