Changes in Understory Composition of Rural North American Temperate Forests after a 14-Year Period with Focus on Exotic and Sensitive Plant Species
Round 1
Reviewer 1 Report
The paper deals with problems of changes in ecosystems due to invasion of species. The changes were observed after of 14 years since the first observation of understorey plant species in chosen forests. Lon-term studies always are very precious because they show real trends and action of many important factors during time. Therefore, this paper has big potential to be interesting for invasion biologists and for forest ecologists, however, some aspects could be improved.
I suggest to include more information about exotic species in supplementary file. What is origin of the species, date of introduction in the study area, degree of invasiveness in the country? Perhaps there are risk of analysis of exotic species in Canada. Reader must know about status of alien species. Why some species are more successful than others?
Authors provided Procrustes analysis in order to “determine the degree of superimposition between 2003 and 2017”. I recommend to do Indicator Species Analysis to show which species are more confined to particular period of time. In R that authors use there are several packages that provide such analysis: labsv, indicspecies.
Minor points:
Line 21: “We found small but significant compositional changes over 14” Over or after? Description of the study design suggest that it was resurvey after 14 years.
Line 22 “younger reforested stands” – it is confusing because at the beginning of abstract you write about forests. It seems that during the period these stands were afforested. Rewrite the sentence
Lines 48-49: Name or mention these global stressor. Climate change, loss of habitats? Etc. Global change is mentioned even in keywords but almost is not mentioned in the text.
Lines 55 – 57: Not only natural senescence and anthropogenic factor matter. Natural disturbance: winds, storm also can contribute to falling of trees from treestand.
Line 194: Write Shannon-Wiener index instead of Shannon diversity index. What formula was used? There are three versions.
Lines 207-208: “We created four binomial or ordinal variables to characterize both past and present land use activities that have occurred in each plot over the 208 last 70 years”. Be specific: how many binomial and how many ordinal variables. By the way, is it binomial or binary variable?
Table 2. There are codes of variables names. In material and methods in the description of them refer to these codes.
Table 2: “Shannon index for species richness of the entire understory plant community, calculated for both the 2003 (H’03) and the 2017 (H’17) inventories” – it is misleading. I guess you calculated Shannon-Wiener index separately for the data for 2003 and for 2017. Rewrite it.
Line 275: Δ%AVG What this delta(?) mean?
Figure 1: It is advisable to create self-explanatory figures. Provide asterisk representing significance above pairs of the bars. For instance *p<0.05 and so on.
Line 401: “biotic resistance hypothesis” it should be provided in the introduction. You did it in line 55 but not so explicitly.
Line 438: it is result of the studies and should be placed in the chapter results. The correlation analysis was not described and meeting requirements of data for parametrical test also was not provided.
Author Response
Please see the attachment.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Line 16 what is the meaning of global change stressors, and how it effect rural natural forest of north America?
Is understory vegetation is a indicator for changing vegetation structure? If yes than how?
Line 53 to 55 can you explain it how mechanism of less diverse and more diverse community is change? And also explain the study area.
Line 66-69 explain it.
This is natural or manmade?
Line 64-84 please reframe the sentence?
Is exotics species change the mechanism of understory tree? Or there is any type of competition between tree species and understory species.
Line 100 procedure to identified the sensitive species?
Due to competition between native and exotics species, have any adverse effect on understory vegetation?
Line 130 What is the procedure of data collection? And how to estimate same size
Line 130- 149 please reframe
What is the plot size for understory vegetation?
Line 207 How to select the ordinal and binomial variable? And how variable related to past and present landuse activity?
In fig :1 What is the reason in change forest structure in RF forest as compared to other?
Table 3 What are reason of gaining and losing of particular species?
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
Authors answered to all my comments and provided substantial chnages that improved the text. In my opinion, the current version can be published.
