Data from: Rapid increases in forest understory diversity and productivity following a mountain pine beetle (Dendroctonus ponderosae) outbreak in pine forests

The current unprecedented outbreak of mountain pine beetle (Dendroctonus ponderosae) in lodgepole pine (Pinus contorta) forests of western Canada has resulted in a landscape consisting of a mosaic of forest stands at different stages of mortality. Within forest stands, understory communities are the reservoir of the majority of plant species diversity and influence the composition of future forests in response to disturbance. Although changes to stand composition following beetle outbreaks are well documented, information on immediate responses of forest understory plant communities is limited. The objective of this study was to examine the effects of D. ponderosae-induced tree mortality on initial changes in diversity and productivity of understory plant communities. We established a total of 110 1-m2 plots across eleven mature lodgepole pine forests to measure changes in understory diversity and productivity as a function of tree mortality and below ground resource availability across multiple years. Overall, understory community diversity and productivity increased across the gradient of increased tree mortality. Richness of herbaceous perennials increased with tree mortality as well as soil moisture and nutrient levels. In contrast, the diversity of woody perennials did not change across the gradient of tree mortality. Understory vegetation, namely herbaceous perennials, showed an immediate response to improved growing conditions caused by increases in tree mortality. How this increased pulse in understory richness and productivity affects future forest trajectories in a novel system is unknown

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pec_et_al_understory_diversity_environmen

Candidate models used for inference on the productivity, richness and evenness of understory plant community responses to <i>Dendroctonus ponderosae</i>-induced tree mortality, light, soil moisture, and nutrients.

<p><i>Notes</i>: The most likely models (<i>w</i>_i>0.90; difference in evidence ratio>2.7) are shown in <b>bold</b>. AIC_C = Akaike’s Information Criterion corrected, ΔAIC_C = difference between AIC_Ci and AIC_{C best model}, <i>w</i>_i = Akaike weight, and evidence ratio = <i>w</i>_{j best model} / <i>w</i>_i.</p><p>Candidate models used for inference on the productivity, richness and evenness of understory plant community responses to <i>Dendroctonus ponderosae</i>-induced tree mortality, light, soil moisture, and nutrients.</p

Model-averaged coefficients and 95% confidence intervals of <i>Dendroctonus ponderosae</i>-induced tree mortality, percent soil moisture, soil nutrients and light predicting evenness of understory woody perennial species in 2012 and 2013.

<p>Model-averaged coefficients and 95% confidence intervals of <i>Dendroctonus ponderosae</i>-induced tree mortality, percent soil moisture, soil nutrients and light predicting evenness of understory woody perennial species in 2012 and 2013.</p

Ranked relative importance of variables associated with the productivity, richness, and evenness of the understory plant community showing model estimates of slope and variance.

<p>The most likely explanatory variables are shown in bold (based on model-average estimate being different from zero when the confidence interval excludes zero).</p><p>Ranked relative importance of variables associated with the productivity, richness, and evenness of the understory plant community showing model estimates of slope and variance.</p

Model-averaged coefficients and 95% confidence intervals of <i>Dendroctonus ponderosae</i>-induced tree mortality, percent soil moisture, soil nutrients and light predicting understory plant community biomass in 2012 and 2013.

<p>Model-averaged coefficients and 95% confidence intervals of <i>Dendroctonus ponderosae</i>-induced tree mortality, percent soil moisture, soil nutrients and light predicting understory plant community biomass in 2012 and 2013.</p

Ranked relative importance of variables associated with evenness of herbaceous and woody understory showing model estimates of slope and variance.

<p>The most likely explanatory variables are shown in bold (based on model-average estimate being different from zero when the confidence interval excludes zero).</p><p>Ranked relative importance of variables associated with evenness of herbaceous and woody understory showing model estimates of slope and variance.</p

Model-averaged coefficients and 95% confidence intervals of <i>Dendroctonus ponderosae</i>-induced tree mortality, percent soil moisture, soil nutrients and light predicting understory plant community richness in 2012 and 2013.

<p>Model-averaged coefficients and 95% confidence intervals of <i>Dendroctonus ponderosae</i>-induced tree mortality, percent soil moisture, soil nutrients and light predicting understory plant community richness in 2012 and 2013.</p

Ranked relative importance of variables associated with richness of herbaceous and woody understory showing model estimates of slope and variance.

<p>The most likely explanatory variables are shown in bold (based on model-average estimate being different from zero when the confidence interval excludes zero).</p><p>Ranked relative importance of variables associated with richness of herbaceous and woody understory showing model estimates of slope and variance.</p

Candidate models used for inference on the evenness of herbaceous and woody understory response to <i>Dendroctonus ponderosae</i>-induced tree mortality, light, soil moisture, and nutrients.

<p><i>Notes</i>: The most likely models (<i>w</i>_i>0.90; difference in evidence ratio>2.7) are shown in <b>bold</b>. AIC_C = Akaike’s Information Criterion corrected, ΔAIC_C = difference between AIC_Ci and AIC_{C best model}, <i>w</i>_i = Akaike weight, and evidence ratio = <i>w</i>_{j best model} / <i>w</i>_i.</p><p>Candidate models used for inference on the evenness of herbaceous and woody understory response to <i>Dendroctonus ponderosae</i>-induced tree mortality, light, soil moisture, and nutrients.</p