Short-Interval, High-Severity Wildfire Depletes Diversity of Both Extant Vegetation and Soil Seed Banks in Fire-Tolerant Eucalypt Forests

Round 1

Reviewer 1 Report

The article "Short-interval, High Severity Wildfire Depletes Diversity of both Extant Vegetation and Soil Seed Banks in Fire-tolerant Eucalypt Forests" focuses on effects of fire-related germination cues and fire frequency on the plant diversity in two different forest types in south-eastern Australia. The relevance of this study to south-eastern  Australia, which is experiencing  wildfires of  unprecedented scale, is unquestionable. The novelty of the work is clearly defined in the Introduction. The work is presented in a well-structured manner. The results are described and well discussed. The conclusions are based on a large experimental material and statistical analysis. I have the following small comments:

1. I would recommend adding literature data on soil temperatures measured in the upper 5 cm layer during wildfires in eucalypt forests of south-eastern Australia.

2.  2.4. Soil seed bank treatment

It is unclear if you used a composite soil sample for the S, LHS, HHS treatments from burnt or unburnt  sites of each forest type? Please, clarify.

Author Response

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Reviewer 2 Report

This is an excellent article and study and worthy of publication in Fire.  I found all sections were well done and the figures as well.

I have two comments.

1. Please include a map of your study area and 2 photos--one for each vegetation type. Note that as a Geographer who works on similar issues in California, I could not imagine the vegetation, nor do I know the location of the study.

2. Speaking of California research, I think the authors miss an opportunity to address this debate at a more international level. In California J. Keeley and is team (See works by Syphard) have published several studies on a similar topic. I find this current work to be superior in that the Keeley work is largely based on historical work and not detailed exploration of the seed bank. In my view, your methods are superior and could be used in California to study the effects of frequent fire on key shrub communities. You might include just a brief review of their work to highlight the parallels and possibilities.

Finally, and this does go back to the lack of photographs, I find it difficult to imagine how more frequent fires in a Mediterranean environment can result in more "intense" and "severe" fire.  Usually, the more frequent the fire, the less intense. Can you explain what the fuels are driving these fires?  Is it rapid recovery of the tree cover? Grasses? Do you have field data--not just dNBR--for fire intensity values such as flame or scorch height?  In other words, I find the more frequent fire argument justified, but the more frequent and more intense is not justified.

Great work.

Author Response

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Reviewer 3 Report

Summary;

An assessment and comparison of soil seed banks from two SE Australian vegetation communities with disparate historic fire regimes and containing sites with increased frequency of fire above historic norms. 

Genral Concept Comments; 

The overall study is a great addition to the literature around the ecological function of seedbanks and their interaction with disturbance regimes. I do think there's an additional question being missed when dormancy breaking mechanisms such as heat and smoke are applied & that is the speed of germination. With your weekly recordings you can still approximate the four week functional germination study design suggested by Baskin & Baskin 2014, where germination after that mark is considered to be from dormant who may have received a breaking que from glasshouse conditions. Additionally, the storage time of dry soil samples is relevant to report as it potentially influences after-ripening seeds (though you account for this in your date of field sampling)

Specific Comments;

51-2 "Soil stored 50 seed is often physically dormant due to a hard, impermeable seed coat" Agreed that many fire adapted seed is physically dormant. Though I disagree with the use of often in combination with soil stored, as it can be interpreted that non dormant seeds persisting in soil is abnormal. The following lines include alternatives to this syndrome. It also may be useful to designate a broad time scale for seed bank persistence. 

189 - Why was litter removed? Are seeds contained in the litter assumed to be consumed by fire?

186, 191- The term sub plot is used. Is this the 10m x 10m plots referred to as the sampling plot in line 155?

197 - What is the justification for 120 minutes heating?

Author Response

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