[MCN] Confirmed, again: Seedling recovery after fire made difficult by heat and drought

Lance Olsen lance at wildrockies.org
Wed Apr 19 10:38:22 EDT 2017

PNAS  Early Edition <http://www.pnas.org/content/early/recent>  April 17 2017doi: 10.1073/pnas.1619014114

Intensifying postfire weather and biological invasion drive species loss in a Mediterranean-type biodiversity hotspot
Jasper A. Slingsby <http://www.pnas.org/search?author1=Jasper+A.+Slingsby&sortspec=date&submit=Submit> et al

Abstract [Bold emphasis added]
http://www.pnas.org/content/early/2017/04/11/1619014114.abstract <http://www.pnas.org/content/early/2017/04/11/1619014114.abstract>

Prolonged periods of extreme heat or drought in the first year after fire affect the resilience and diversity of fire-dependent ecosystems by inhibiting seed germination or increasing mortality of seedlings and resprouting individuals. This interaction between weather and fire is of growing concern as climate changes, particularly in systems subject to stand-replacing crown fires, such as most Mediterranean-type ecosystems. We examined the longest running set of permanent vegetation plots in the Fynbos of South Africa (44 y), finding a significant decline in the diversity of plots driven by increasingly severe postfire summer weather events (number of consecutive days with high temperatures and no rain) and legacy effects of historical woody alien plant densities 30 y after clearing. Species that resprout after fire and/or have graminoid or herb growth forms were particularly affected by postfire weather, whereas all species were sensitive to invasive plants. Observed differences in the response of functional types to extreme postfire weather could drive major shifts in ecosystem structure and function such as altered fire behavior, hydrology, and carbon storage. An estimated 0.5 °C increase in maximum temperature tolerance of the species sets unique to each survey further suggests selection for species adapted to hotter conditions. Taken together, our results show climate change impacts on biodiversity in the hyperdiverse Cape Floristic Region and demonstrate an important interaction between extreme weather and disturbance by fire that may make flammable ecosystems particularly sensitive to climate change.
“Finally, we are committed to a high level of consumption because, whether we need the goods or not, we very much need the employment their production provides …. We are chained to a high level of production and consumption not by the pressure of want but by the urgencies of economic security.”

John K. Galbraith.
“How much should a country consume?”
In Jarrett, Henry (editor), Perspectives on Conservation.  John Hopkins Press. 1958
“In an attempt to clarify the issues, first let us advance the following proposition: The more wasteful a society the greater the employment opportunities.”

Kimon Valaskakis, Peter S. Sindell, J. Graham Smith, and Iris Fitzpatrick-Martin. The Conserver Society. 1970. Harper & Row.

"Here we tested how well geology predicts the species diversity of 14 US states and three Canadian provinces, using a comprehensive new spatial dataset. Results of linear regressions of species diversity on all possible combinations of 23 geophysical and climatic variables indicated that four geophysical factors; the number of geological classes, latitude, elevation range and the amount of calcareous bedrock, predicted species diversity with certainty (adj. R2=0.94). To confirm the species-geology relationships we ran an independent test using 18,700 location points for 885 rare species and found that 40% of the species were restricted to a single geology. Moreover, each geology class supported 5–95 endemic species and chi-square tests confirmed that calcareous bedrock and extreme elevations had significantly more rare species than expected by chance (P,0.0001), strongly corroborating the regression model. Our results suggest that protecting geophysical settings will conserve the stage for current and future biodiversity and may be a robust alternative to species-level predictions.”

Anderson MG, Ferree CE (2010) Conserving the Stage: Climate Change and the Geophysical Underpinnings of Species Diversity. PLoS ONE 5(7): e11554. 
I have the pdf , but it’s open access here:   doi:10.1371/journal.pone.0011554 

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