Fire Exclusion Destroys Habitats for At-Risk Species in a British Columbia Protected Area
Round 1
Reviewer 1 Report
I found that this paper had potential but suffered from be too general and could have drawn on some more relevant literature (journals and grey literature) dealing with this subject in California, Oregon, Washington and British Columbia. Prescribed fire in Garry oak ecosystems has been undertaken by Parks Canada (mentioned in paper), the Nature Conservancy, US Parks Service, and various other conservation organizations hence the concept of using fir as a restoration tool is not a new one. Where the papers strengths lie are with the dendroecology and aerial/sat histric land-use change data. I would suggest adding Pellatt, McCoy and Mathewes (2015) Biodivesity and Conservation into the Introduction as they discuss fire return intervals in Garry oak ecosystems in detail.
The discussion on Taylor Checkerspot Butterfly is interesting but lacks a detailed restoration plan (as does the paper) which it implies it is providing knowledge for. Much introductory text is committed to the butterfly but little substantial follow-up in the discussion/cunclusion occurs hence this could certainly be improved.
Also note that oaks can be effective riparian species and that soil moisture related to invasive species such as agronomic grasses may be important. Also note that light availibility is likely a greater issue than soil moisture in sites occupied by Douglas-fir and other conifers.
As for the sampling design I feel that the nature of the transects perpendicular to the vegetation zone may over represent the role of conifers in the structure of the tree stands. It may also be a design where it is difficult to find fire scars with an increment borer. Using size/age coherts may have been a better approach.
In a statement (line 209) you state that in 1874 the site had not experienced fire for more than 100 year. Is this correct? That would mean that there was not fir since 1774 or before the Little Ice Age or 250 years? So it doesn't jump out to me as a fire adapted ecosystem? You mention that there was a fire at the site in the later 20th Century. It would seem to me that there could have been more research into the differences in the burned and unburned area of the Garry oak site.
I think that the paper is publishable but needs some work to convince me that this is a paper that will inform land managers that fire in Helliwell Park will be an appropriate tool for the restoration of GOEs and butterflies.
Line 26
Add McCune, J.L., Pellatt, M.G., and Vellend, M. (2013). Multidisciplinary synthesis of long-term human-ecosystem interactions: A perspective from the Garry oak ecosystem of British Columbia. Biological Conservation. 166: 293-300
Line 39 – Note that many Garry oak ecosystems exist on rocky bluffs and islets/islands so I would say Many or Most but not all GOEs have been impacted by roads, agriculture or urban development.
Line 45 – INCORRECT. Note that the Taylor Checkerspot exists on Denman Island (adjacent to Hornby Island). “Taylor’s Checkerspot butterflies are extremely rare! In Canada, they are only found on Denman Island. They’re clinging to survival within small portions of seasonal wetland and meadow habitats in a former clear-cut logging area in the new Denman Island Provincial Park and Protected Area, as well as in some adjacent private properties and land owned by the Denman Conservancy Association.” https://www2.gov.bc.ca/gov/content/environment/plants-animals-ecosystems/species-ecosystems-at-risk/implementation/conservation-projects-partnerships/taylors-checkerspot
I find the section between 45 and 65 a bit out of place in that you are writing a paper looking at aerial photo/sat image change interpretation and tree ring analysis not Taylor Checkerspot Butterfly and that you facts on the SAR listed species is incorrect.
Line 55 – Note that GO can exist in a range of areas and persist in places that are too dry for Douglas-fir. They can also be a riparian species depending on the time that the water subsides. The drying of soils from Douglas-fir is not likely a causal mechanism for GO decline (although it can contribute) but rather the shading of the GO. See Gedalof and Franks Forests2019, 10, 381; doi:10.3390/f10050381
Line 63 – You may want to mention that prescribed fir on Garry oak ecosystems has been undertaken in California, Oregon, Washington and BC (Cowichan Nature Preserve, San Juan Islands, USNPS, Fort Lewis McChord, and Tumbo Island in the Gulf Island National Park Reserve).
Line 95 – I am concerned that this sampling technique is adequate to represent Garry oak – wouldn’t size cohorts been a better way to select trees?
Line 117 – Too look for fire scars? Trauma rings? Or just age?
Line 119 – how would you ID scars from a visual survey?
Line 126-127 – What is the logic here?
Line 130 – what is “clutter”?
Section 2.5
Explain how the dead GO and live DF is a measure of anything? And what would that be? Shading, drought, disease???
Figure 4 and associated analysis. Did the transects perdindicular to the shore bias the study toward conifers as I would expect the “GO” to exist parallel to the shore. Also how much thinning of DF may have been done at the site? Did you concentrate on where the relatively recent fire was?
Lines 207 – 214 – I find this section confusing. In a statement (line 209) you state that in 1874 the site had not experienced fire for more than 100 year. Is this correct? That would mean that there was not fir since 1774 or before the Little Ice Age or 250 years? So it doesn't jump out to me as a fire adapted ecosystem? You mention that there was a fire at the site in the later 20th Century. It would seem to me that there could have been more research into the differences in the burned and unburned area of the Garry oak site.
Line 247 – How do you know that the conifers are responding to decadal warming? Is this not just niche competition and succession?
Line 254 – What is a fire resilient ecosystem. Is it different than a fire-adapted ecosystem? Or a fire prone ecosystem?
Line 263 – Your references are general and not in your region – how do you know that the non-native plants are more flammable than the native plants at your site?
Line 295 There are several examples of prescribed fires in the Pacific Northwest of North America. You should draw upon the literature for study design recommendations. See Fire as a Restoration Tool in Pacific Northwest Prairies and Oak Woodlands: Challenges, Successes, and Future Directions
Authors: Sarah T. Hamman, Peter W. Dunwiddie, Jason L. Nuckols, and Mason McKinley
Source: Northwest Science, 85(2) : 317-32
See https://www.fs.fed.us/database/feis/plants/tree/quegar/all.html
See Northwest Science 85(2) for a number of good papers on Garry oak.
Copes-Gerbitz et al 2017 A Multi-Proxy Environmental Narrative of Oregon White Oak (Quercus garryana) Habitat in the Willamette Valley, Oregon. Northwest Science 91(2):160-185
Line 306 - 309 is incorrect. Change
The Tumbo Island (Gulf Islands National Park 305 Reserve) restoration and prescribed burning program was initiated in 2016 by Parks Canada.
Remove ...
and is co-managed by Parks Canada, Cowichan First Nation, and the Capital Regional District
Note no mechanical thinning was undertaken.
Author Response
REVIEW REPORT 1: I found that this paper had potential but suffered from be too general and could have drawn on some more relevant literature (journals and grey literature) dealing with this subject in California, Oregon, Washington and British Columbia. Prescribed fire in Garry oak ecosystems has been undertaken by Parks Canada (mentioned in paper), the Nature Conservancy, US Parks Service, and various other conservation organizations hence the concept of using fir as a restoration tool is not a new one. Where the papers strengths lie are with the dendroecology and aerial/sat histric land-use change data. I would suggest adding Pellatt, McCoy and Mathewes (2015) Biodivesity and Conservation into the Introduction as they discuss fire return intervals in Garry oak ecosystems in detail.
The discussion on Taylor Checkerspot Butterfly is interesting but lacks a detailed restoration plan (as does the paper) which it implies it is providing knowledge for. Much introductory text is committed to the butterfly but little substantial follow-up in the discussion/cunclusion occurs hence this could certainly be improved.
Also note that oaks can be effective riparian species and that soil moisture related to invasive species such as agronomic grasses may be important. Also note that light availibility is likely a greater issue than soil moisture in sites occupied by Douglas-fir and other conifers.
As for the sampling design I feel that the nature of the transects perpendicular to the vegetation zone may over represent the role of conifers in the structure of the tree stands. It may also be a design where it is difficult to find fire scars with an increment borer. Using size/age coherts may have been a better approach.
In a statement (line 209) you state that in 1874 the site had not experienced fire for more than 100 year. Is this correct? That would mean that there was not fir since 1774 or before the Little Ice Age or 250 years? So it doesn't jump out to me as a fire adapted ecosystem? You mention that there was a fire at the site in the later 20th Century. It would seem to me that there could have been more research into the differences in the burned and unburned area of the Garry oak site.
I think that the paper is publishable but needs some work to convince me that this is a paper that will inform land managers that fire in Helliwell Park will be an appropriate tool for the restoration of GOEs and butterflies.
Author reply: Thank you for these helpful comments. We have endeavored to include more references from the literature into our manuscript (13 in total), including Pellatt et al. 2015 (line 556). We have added more follow up surrounding the effects of conifer encroachment on Taylor’s Checkerspot butterfly into the Discussion at line 424, line 434, and line 491. In addition to our discussion on conifer shading on line 441, and Figure 4 caption which lists shading as a potential contributing factor to Garry oak mortality (line 372), we have revised text in the Introduction to impart the importance of shading as a potential contributing factor in conifer encroachment into Garry oak ecosystems (line 100). We have addressed comments relating to survey design and the fire history of Helliwell Provincial Park in detail below. We believe the revisions made based on these comments have greatly improved our manuscript, and thank the reviewer for the suggestions. All line numbers refer to the tracked changes document.
Line 26
Add McCune, J.L., Pellatt, M.G., and Vellend, M. (2013). Multidisciplinary synthesis of long-term human-ecosystem interactions: A perspective from the Garry oak ecosystem of British Columbia. Biological Conservation. 166: 293-300
Author reply: Done – line 26.
Line 39 – Note that many Garry oak ecosystems exist on rocky bluffs and islets/islands so I would say Many or Most but not all GOEs have been impacted by roads, agriculture or urban development.
Author reply: True, we have revised line 41 to read: “Almost all remaining Garry oak and associated ecosystems have been directly impacted by roads, agriculture, and urban development [20].”.
Line 45 – INCORRECT. Note that the Taylor Checkerspot exists on Denman Island (adjacent to Hornby Island). “Taylor’s Checkerspot butterflies are extremely rare! In Canada, they are only found on Denman Island. They’re clinging to survival within small portions of seasonal wetland and meadow habitats in a former clear-cut logging area in the new Denman Island Provincial Park and Protected Area, as well as in some adjacent private properties and land owned by the Denman Conservancy Association.” https://www2.gov.bc.ca/gov/content/environment/plants-animals-ecosystems/species-ecosystems-at-risk/implementation/conservation-projects-partnerships/taylors-checkerspot
Author reply: We have revised lines 89-91 to read: “For some time, a 1996 sighting of Taylor’s Checkerspot in Helliwell Provincial Park on Hornby Island was presumed to be the last evidence of the species in Canada. [24]. Fortunately, in 2005, a small sub-population (15 individuals) was found on nearby Denman Island [25].”
I find the section between 45 and 65 a bit out of place in that you are writing a paper looking at aerial photo/sat image change interpretation and tree ring analysis not Taylor Checkerspot Butterfly and that you facts on the SAR listed species is incorrect.
Author reply: Many species have declined or been extirpated as a consequence of Garry oak habitat decline and degradation (as much as 97% of all Garry Oak-associated habitat has been lost in British Columbia). We have used Taylor’s Checkerspot as a regionally important example due to its loss from this particular site and its small population on nearby Denman Island. Additionally, BC Parks and community organizers have plans to reintroduce the butterfly to the park in the near future [26]. Using remote sensing and tree ring analysis we determined the rate of habitat loss during the Taylor’s Checkerspot population decline and eventual crash on Hornby Island. On line 92 we report that the only remaining Taylor’s Checkerspot butterfly population is listed as endangered by the Canadian Species-at-Risk Act as per the Species at Risk Public Registry (https://wildlife-species.canada.ca/species-risk-registry), which to our knowledge is correct. We have revised line 43 to read: “This loss of habitat has put over 100 Garry oak associated species at risk [19], including the Taylor’s Checkerspot butterfly (Euphydryas editha taylori), whose populations have declined drastically over the past century [19,21-22].”
Line 55 – Note that GO can exist in a range of areas and persist in places that are too dry for Douglas-fir. They can also be a riparian species depending on the time that the water subsides. The drying of soils from Douglas-fir is not likely a causal mechanism for GO decline (although it can contribute) but rather the shading of the GO. See Gedalof and Franks Forests2019, 10, 381; doi:10.3390/f10050381
Author reply: Thank you for this. We have added the Gedalof and Franks 2019 reference following sentences to line 101: “This can contribute to a competition for moisture between Garry oak and Douglas fir, and fast-growing and taller Douglas fir trees can achieve dominant canopy positions, ultimately shading out both mature and sapling Garry oak [31]”.
Line 63 – You may want to mention that prescribed fir on Garry oak ecosystems has been undertaken in California, Oregon, Washington and BC (Cowichan Nature Preserve, San Juan Islands, USNPS, Fort Lewis McChord, and Tumbo Island in the Gulf Island National Park Reserve).
Author reply: Thank you for this suggestion and these references. We report on prescribed fire programs in the Discussion on line 859. We have incorporated all the programs listed above into this line which reads: “In addition to the Tumbo Island project, there are many other established prescribed burning programs in Garry oak ecosystems including; Willamette Valley, Oregon [57], Cowichan Nature Preserve, British Columbia [58], Redwood National Park, California [59], and in the San Juan Islands, Washington [60]. These fire restoration programs provide important information on how to successfully reintroduce fire in populated areas with complex disturbance histories and management concerns and could serve as models for the re-introduction of prescribed burning in Helliwell Provincial Park.”
Line 95 – I am concerned that this sampling technique is adequate to represent Garry oak – wouldn’t size cohorts been a better way to select trees?
Author reply: We believe belt transects were an appropriate survey design which allowed us to capture the encroachment of conifers into a historical Garry oak meadow. We have justified this method in further detail in the comments below.
Line 117 – Too look for fire scars? Trauma rings? Or just age?
Author reply: To better describe our methods we have revised this section to read: “To reconstruct the fire history of the park, we systematically searched all old growth trees (estimated by dbh, branch size and height) for the presence of superficial fire scars, which are lobed folds of bark generally found near the tree base [40]. We also cored five large diameter Douglas-fir trees located in the southern corner of the park to age the old growth Douglas fir” (lines 336-339). Due to park management regulations we were unable to sample cross section from trees.
Line 119 – how would you ID scars from a visual survey?
Author reply: To better inform the reader on how we defined fire scars we have revised line 336 to read: “we systematically searched all old growth trees (estimated by dbh, branch size and height) for the presence of superficial fire scars, which are lobed folds of bark generally found near the tree base [40].”
Superficial fire scars can be identified visually by searching for ‘catfaces’, which are open scars resulting from one or more fires. Fire scars result from lethal heating of the cambium layer, which eventually sloughs off of the tree, resulting in an open scar. The lobed bark appears as the tree attempts to cover the wound with new radial growth. More information on identifying catfaces can be found in:
Arno SF, Sneck KM. A Method for Determining Fire History in Coniferous Forest of the Mountain West. 1977. A report prepared by the Intermountain Forest and Range Experiment Station, Forest Service, U.S. Department of Agriculture.
Line 126-127 – What is the logic here?
Author reply: We reason that native forbs, grasses, and Garry oak saplings could still establish near/next to individual trees. However, dense brush would exclude these species from establishing. We are interested in native forbs and grasses as they are foraging material for the Taylors Checkerspot butterfly. We have revised line 327 to include this information.
Line 130 – what is “clutter”?
Author reply: We have removed the word clutter and revised line 331 to read: “For map clarity, four years (1952, 1972, 1996, and 2014) at approximately twenty-year intervals across six decades were selected to assess land-use changes and calculate the historic Garry oak meadow extent”. This sentence is referring to the crowding effect that would be visible on the Figure 5 if we included spatial polygons for all changes in meadow extent evident from aerial photographs taken at nine points in time. Instead, to simplify Figure 5, we chose to map the meadow extent at four points in time, which collectively spans six decades.
Section 2.5
Explain how the dead GO and live DF is a measure of anything? And what would that be? Shading, drought, disease???
Author reply: We tested the association between dead Garry oak and live Douglas fir to see if the presence of Douglas fir could predict the presence of dead Garry oak (line 343). We found that the two were not independent (line 471). The mechanism behind this association is not within the scope of this research, but it could be due to several factors such as the ones listed above (and most likely due to a combination of drought, competition, and shading).
Figure 4 and associated analysis. Did the transects perdindicular to the shore bias the study toward conifers as I would expect the “GO” to exist parallel to the shore. Also how much thinning of DF may have been done at the site? Did you concentrate on where the relatively recent fire was?
Author reply: Good questions. Thinning of Douglas fir was only undertaken on the tree “islands” located within the meadow (and not within the forest/wetland complex) at the Southwest corner of the park (Figure S4). Therefore, all thinning was done outside of the belt transects. Our transects did not extend to where the 1985 fire was (located in the northeast quadrant of the park; Figure S3). Based on another reviewer’s comments about redundancy between Figure 4 and Figure 2, we have removed Figure 4 from the manuscript.
We do not believe the perpendicular belt transects biased the study. Based on a land survey done in 1875 by Joseph Carey and discussions with Parks managers we believe the entire region we performed our belt transects in was once Garry oak meadow (see Joseph Carey’s survey map below, also included in the Supplementary Materials as Figure S1). Therefore, we believe this is an appropriate region of the park to capture a gradient of encroaching conifers.
(Please check Figure S1 in attached cover letter)
Figure S1: Joseph Carey’s survey map of the southeastern Hornby Island. The region that is now known as Helliwell Park is located near St. John’s Point.
Lines 207 – 214 – I find this section confusing. In a statement (line 209) you state that in 1874 the site had not experienced fire for more than 100 year. Is this correct? That would mean that there was not fir since 1774 or before the Little Ice Age or 250 years? So it doesn't jump out to me as a fire adapted ecosystem? You mention that there was a fire at the site in the later 20th Century. It would seem to me that there could have been more research into the differences in the burned and unburned area of the Garry oak site.
Author reply: Yes, Comox First Nation, who traditionally inhabited the land now called Helliwell Park experienced a severe population decline due to smallpox post-contact (1792), which restricted their area of land used. Based on Joseph Carey’s 1875 land surveys, which estimate the conifer cohort age and describe the plant communities surrounding the “grassy hills”, it has been suggested by the authors of the Helliwell Provincial Park Ecosystem Based Plan that the grassland/Oak complex may have extended further in the past. We report this hypothesis in the manuscript on line 660: “it has been estimated that Helliwell Park might not have experienced cultural fire activity in approximately 100 years”.
An extensive shell midden in a bay in the northeast corner of the park, as well as ethnographies from the Comox First Nation, display long-term and high-use occupation prior to contact. Additionally, the presence of persistent camas beds in the meadows above the bluff along the southern edge of the park, indicate the probable use of consistent anthropogenic fire. From several accounts, we are confident that this is a fire adapted system.
Further research into the differences between burned and unburned areas of Helliwell Park would be a great avenue for research before a potential prescribed burn (although the sample size for burned areas would be low).
Please note that we have revised the Discussion relating to the past First Nations land use to better explain the timeline of events that has led to a lack of fire scars in Helliwell Park. Beginning on line 653 this paragraph now reads as follows: “Garry oak ecosystems retain the majority of larger diameter fuels within the canopy layer and do not easily ignite except when leaf tissue moisture is low [48]. Burning Garry oak meadows every few years was likely a common practice by coastal First Nations to maintain habitat for camas (Camassia spp.) and other important food species [9-10]. These low severity fires consumed available fuels, often leaving no evidence of fire on the landscapes [10]. The lack of fire-scarred trees suggest that fire activity was likely suppressed prior to widespread fire suppression policies implemented in British Columbia in the 1920s [8]. Historic documents indicate that First Nations populations on Hornby Island were significantly affected by three smallpox epidemics at colonial contact in 1792, and it has been estimated that Helliwell Park might not have experienced cultural fire activity in approximately 100 years (Figure S1) [43]. A long history of commercial logging on Hornby Island has also decreased the extent of old growth trees containing fire scars [43]. Unfortunately, the lack of fire evidence in the form of living fire scarred trees limits the potential to reconstruct historical fire activity in the park [8]. Soil charcoal and fossil pollen analysis, and more ethnohistorical research and traditional ecological knowledge is required to understand the fire history of Helliwell Provincial Park [49,50] including the spatial and temporal characteristics of historic burning by First Nations.”
Line 247 – How do you know that the conifers are responding to decadal warming? Is this not just niche competition and succession?
Author reply: We have removed this statement. Line 576 now reads: “Douglas-fir and shore pine trees have also experienced pulses of recruitment likely associated with the cessation of livestock grazing in the 1960s”.
Line 254 – What is a fire resilient ecosystem. Is it different than a fire-adapted ecosystem? Or a fire prone ecosystem?
Author reply: We have revised the manuscript to include definitions of fire resilient on line 35: ecosystems that recover quickly from fire disturbances and fire adapted on line 30: organisms with life history strategies that tolerate fire. Both types of ecosystems can be fire-prone (exposed to a fire regime).
Line 263 – Your references are general and not in your region – how do you know that the non-native plants are more flammable than the native plants at your site?
Author reply: Generally, widespread invaders (such as English Ivy) cause changes to fire regimes (i.e. vines can spread fires to tree crowns). However, we are not sure if non-native or native plants would be more flammable at our specific site. Therefore, we have re-worded this sentence to: “The presence of these invasive species has the potential to increase the fire hazard in the park, as species like English holly and English Ivy could be more flammable than native plants” (line 650).
Line 295 There are several examples of prescribed fires in the Pacific Northwest of North America. You should draw upon the literature for study design recommendations. See Fire as a Restoration Tool in Pacific Northwest Prairies and Oak Woodlands: Challenges, Successes, and Future Directions
Authors: Sarah T. Hamman, Peter W. Dunwiddie, Jason L. Nuckols, and Mason McKinley
Source: Northwest Science, 85(2): 317-32
See https://www.fs.fed.us/database/feis/plants/tree/quegar/all.html
See Northwest Science 85(2) for a number of good papers on Garry oak.
Copes-Gerbitz et al 2017 A Multi-Proxy Environmental Narrative of Oregon White Oak (Quercus garryana) Habitat in the Willamette Valley, Oregon. Northwest Science 91(2):160-185
Author reply: Thank you for these references. We have incorporated them into our Discussion of prescribed fire implementation on line 666, 672, 857, and line 889
Line 306 - 309 is incorrect. Change
The Tumbo Island (Gulf Islands National Park 305 Reserve) restoration and prescribed burning program was initiated in 2016 by Parks Canada.
Remove ...
and is co-managed by Parks Canada, Cowichan First Nation, and the Capital Regional District
Note no mechanical thinning was undertaken.
Author reply: We have removed the above sentences as requested. Lines 868 - 872 now read: “A Parks Canada (Gulf Islands National Park Reserve) restoration and prescribed burning program was initiated on Tumbo Island, a small, uninhabited island north of Saturna Island, British Columbia. In September 2016 four 50 x 50 m plots (totaling one hectare in area) were burnt. The prescribed burn created more open forest floor and removed 150 years of ground fuel.”
Author Response File: 
Author Response.pdf
Reviewer 2 Report
This paper presents a case study addressing the loss of Garry oak habitat as a result of Douglas-fir encroachment in British Columbia, using a variety of analytical methods. The paper also provides a habitat assessment to inform management recommendations for the restoration of Garry oak habitat in the study area. This paper provides good justification for the study, despite the limited area of inference. The analytical methods are sound and justified by the data available. I appreciated the way that the cultural history of the study location was discussed as well as the natural history; this provided needed context. There are some inconsistencies in the results that should be addressed to make the paper more cohesive but overall it is well written and would make a good contribution to the journal.
Line edits:
Line 36: move the parenthetical binomial nomenclature for Garry oak to the first mention of the species (line 32)
Line 117: The exact number of trees coured would be more informative than “several)
Line 140: This section heading seems not to correspond well with the information in that section. The section is about both historical and contemporary forest structure attributes in the transects. Likewise for section heading 3.2 “Mapping stand density” (line 175); stand density is described in the previous section.
Line 160: Figure 4 doesn’t seem to correspond to any particular hypotheses about the expectation that density would vary along an east-west gradient. Additionally, the figure caption includes information (“The forest edge containing transects 1-4 are currently encroaching into the meadow at a rate of 0.5 meters per year”) that is not contained in the figure and thus would be more appropriate elsewhere. I recommend removing this figure since the information is repetitive of Figure 2. Also, the appropriate y-axis label would be “Density (trees/ha)”.
Lines 165-166: “Counting of branch whorls on every fifth sapling (< 7.5 cm dbh, > 15 cm)…” information would be more appropriate in the methods than in the results.
Line 175: “Mapping stand density” seems not to directly correspond with the information in this section, especially since the opening paragraph doesn’t describe any measurements of density (specifically using the metric of trees/ha). A different section heading would be more appropriate.
Line 192-194: These results seem out of place here. Are they derived from the spatial analysis? If so, I recommend providing more detail, and if not, I recommend removing them or moving to the previous section. It’s not clear when it’s said that there is “no significant difference” what data is being compared to what other data.
Line 203: 60,000 people per year? In what months exactly?
Line 206: “The lack of fire-scarred tree”- this is not mentioned at all in the results and should be if you are going to bring it up in the discussion.
Line 218: re. Figure 4: I’m not sure you need an entire figure to support this statement so my comments above still stand.
Comments for author File: Comments.pdf
Author Response
REVIEW REPORT 2: This paper presents a case study addressing the loss of Garry oak habitat as a result of Douglas- fir encroachment in British Columbia, using a variety of analytical methods. The paper also provides a habitat assessment to inform management recommendations for the restoration of Garry oak habitat in the study area. This paper provides good justification for the study, despite the limited area of inference. The analytical methods are sound and justified by the data available. I appreciated the way that the cultural history of the study location was discussed as well as the natural history, this provided needed context. There are some inconsistencies in the results that should be addressed to make the paper more cohesive but overall it is well written and would make a good contribution to the journal.
Author reply: Thank you for these helpful comments. We have addressed all line edits below and have made several changes to our results section (including adding a new section to report the results of our fire reconstruction). We believe that these edits have much improved this manuscript. All line numbers refer to the tracked changes document.
Line edits:
Line 36: move the parenthetical binomial nomenclature for Garry oak to the first mention of the species (line 32)
Author reply: Done (line 34).
Line 117: The exact number of trees coured would be more informative than “several)
Author reply: Revised, the sentence now reads “we also cored five large diameter Douglas-fir trees located in the southern corner of the park to age the old growth Douglas-fir” (line 338). We have also revised line 530 in our Results to read: “We attempted to core several (n = 5) large diameter (>100 cm dbh) trees; however, complacent ring width and heart rot rendered fore reconstructions impossible [34]”.
Line 140: This section heading seems not to correspond well with the information in that section. The section is about both historical and contemporary forest structure attributes in the transects. Likewise for section heading 3.2 “Mapping stand density” (line 175); stand density is described in the previous section.
Author reply: Thank you for these helpful comments. We have revised section heading 3.1 to “Reconstructing historical and contemporary forest structure via belt transects” (line 249) and section heading 3.2 to “Reconstructing historical and contemporary forest structure via remote sensing” (line 374). We believe these new headings better introduce the information contained in the section. Additionally, we have revised headings 2.2 and 2.3 in the Methods to match headings 3.1 and 3.2 in the Results.
Line 160: Figure 4 doesn’t seem to correspond to any particular hypotheses about the expectation that density would vary along an east-west gradient. Additionally, the figure caption includes information (“The forest edge containing transects 1-4 are currently encroaching into the meadow at a rate of 0.5 meters per year”) that is not contained in the figure and thus would be more appropriate elsewhere. I recommend removing this figure since the information is repetitive of Figure 2. Also, the appropriate y-axis label would be “Density (trees/ha)”.
Author reply: Thank you for this suggestion, we have removed Figure 4 from the manuscript.
Lines 165-166: “Counting of branch whorls on every fifth sapling (< 7.5 cm dbh, > 15 cm)...” information would be more appropriate in the methods than in the results.
Author reply: Revised, we have removed this information from the Results and revised line 299 in the Methods to read “Tree whorls on every fifth sapling (> 7.5 dbh, < 15 cm dbh) were counted to estimate the age of tree saplings and estimates of sapling age were verified by counting rings on the stumps of trees that had been recently thinned outside the study area”.
Line 175: “Mapping stand density” seems not to directly correspond with the information in this section, especially since the opening paragraph doesn’t describe any measurements of density (specifically using the metric of trees/ha). A different section heading would be more appropriate.
Author reply: We have revised this heading to “Reconstructing historical and contemporary forest structure via remote sensing” as per earlier suggestions (line 485).
Line 192-194: These results seem out of place here. Are they derived from the spatial analysis? If so, I recommend providing more detail, and if not, I recommend removing them or moving to the previous section. It’s not clear when it’s said that there is “no significant difference” what data is being compared to what other data.
Author reply: Thank you for this comment. This analysis was based on data collected via belt transects, and thus we have removed it from the remote sensing section and relocated it into the belt transect section, starting on line 347, which now reads: “Belt transects contained Douglas-fir, shore pine, and Garry oak trees in drier upland sites and Pacific crabapple (Malus fusca [Raf.] C. K. Schneid), aspen (Populus tremuloides Michx.), and western redcedar in wetter sites (Figure 2). There was no significant difference in the species composition (Kruskal-Wallis chi-squared = 4.8214, df = 2, p-value = 0.08975), dbh (Kruskal-Wallis chi-squared = 212.8083, df = 225, p-value = 0.7102) and height (Kruskal-Wallis chi-squared = 186.8888, df = 168, p-value = 0.1514) of trees in each belt transect.”
Line 203: 60,000 people per year? In what months exactly?
Author reply: To better clarify when Helliwell park visits are at their peak, we have revised this section to read: “Helliwell is a popular park, drawing upwards of 60,000 visitors per year (when last censused in 2001)[43]. Many of these visits are concentrated in the summer months when the population of Hornby Island quadruples [44]” (lines 542 - 544).
Line 206: “The lack of fire-scarred tree”- this is not mentioned at all in the results and should be if you are going to bring it up in the discussion.
Author reply: Thank you for this suggestion. We have added a new section in the Results: “3.3 Reconstructing fire dynamics in Helliwell Provincial Park” which reports the results pertinent to systematic surveys for fire scarred trees (line 519).
Line 218: re. Figure 4: I’m not sure you need an entire figure to support this statement so my comments above still stand.
Author reply: True. As we have removed Figure 4 from the manuscript, we have revised this line to refer to Figure 5, which we also believe displays rapid encroachment of conifers into the Garry Oak meadow and wetland area.
Round 2
Reviewer 1 Report
My comments have been adequately addressed.
