Areas Of Agreement

We did not mean that the recruitment of trees was done by fire. Stevens et al. suspect that pulsed recruitment in the absence of fire has shaped the distribution of ages in many AAF plots. We agree that this process has been a historical process. There is also a consensus that a dominant cohort of trees will occur after a severe fire, but that later in the development of stability, recruitment of undergrowth with a favourable climate or after insect epidemics may occur. This, along with the presence of some trees in front of the fire, will create an uneven level, but there may still be a dominant size class of excess that was put in place after the fire. In a recent PLOS ONE paper, we conducted a factual analysis of current and historical fire patterns and concluded that the traditionally defined baseline conditions of low-gravity incendiary regimes for Ponderosa pines (Pinus ponderosa) and mixed conifer forests were incomplete and that there was no significant variability in forest structure and denbrandt regimes. Stevens et al. (this edition) agree that heavy rope fires were part of these forests, but disagree that one of the many sources of evidence from a large number of forest inventory and analysis (FIA) sites in the western United States supports our conclusions that serious fires in these forests played a minor role. Here we identify areas of agreement and disagreement over past fire, and analyze the methods used by Stevens et al. to evaluate FIA stand-age data. We found a big problem with a calculation that they concluded that the FIA data were not useful in assessing incendiary regimes. Their calculation, as well as a narrowing of the definition of high-gravity fires from the one we used, lead to a great underestimation of conditions that correspond to historical fires of high gravity.

The age data of the FIA have limitations, but they are consistent with other sources of landscape data to support a broader paradigm on historical variability of fire in Ponderosa and spinach forests as traditional, as described in our previous PLOS paper. The spatial structure of convergences and differences of opinion is essential to understanding whether differences of opinion can be linked to specific issues. The discussion with Senate leaders, moderated by Crains New York Business, provided an overview of some of the areas of convergence and divergence within the legislative framework upstream. In the six regions we analyzed in Odion et al., the beginning of fire reduction about a century ago coincides with a dramatic reduction in the inauguration of trees forming the predominant overhead classes. Thus, the elimination of the fire has had a profound impact on the recruitment process in many areas. Post-fire recruitment, as Stevens et al. suspected, could not be responsible for the abundant establishment pattern of predominant tree size classes prior to firefighting.

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