Comparison of Natural Regeneration in Natural Grassland and Pine Plantations across an Elevational Gradient in the Páramo Ecosystem of Southern Ecuador

Round 1

Reviewer 1 Report

The paper shows the differences in characteristics of ground vegetation (species composition and cover) between pine plantations and natural grasslands in paramo ecosystems of S Ecuador. In the study the effect of some soil properties as well as attributes of pine stands on the main scientific question is also considered.

In general, I find the paper interesting and well designed and written. However, in my opinion, before the possible publication the Authors should amend the paper with regard to the following points (moderate/minor revision required):  

Moderate points:

The paper title is not fully consistent with the aim of the study formulated in l. 17-20 and l. 99-103. In the aim the main stress is put on the effect of elevation and different land use, while in the paper’s title on abiotic and biotic factors (i.e. soil properties and plantation attributes). However, in fact, in the entire article, the factors are of secondary importance, which is consistent with the aim formulated, but not with the paper’s title. Thus, the title needs correction. Taking into account that the Authors found the clear decrease of plant biodiversity after afforestation, the statement that “these plantations could be managed for ecological restoration purposes” (l. 451-452) is strongly controversial. In fact what kind of “restoration” the Authors mean here? Would they like to “restore” natural grasslands consisted of native species by introducing not-native pine stands of lower biodiversity? I do not of course undermine obvious positive effects of establishing pine plantations, e.g. with regard to timber production and possible C sequestration; however, linking it with the positive effect on biodiversity is not reasonable, at least based on the results of the reviewed study. Thus, the issue should be overlooked by the Authors throughout the paper, not to make a reader confused.   Similar controversy refers to the paragraph in l. 69-75, in which the Authors a little bit introduce to a reader ecological importance of plantations in a broaden (global) sense. The Authors indicate here only the positive effects of such land use. However, to objectively introduce the issue to a reader, the adverse environmental effects of plantations should be also mentioned in the paragraph. It should be explained why the slope aspect was not included in the study, because, especially just with regard to mountainous areas, this factor is important for ground vegetation patterns (see e.g. Cantlon J.E., 1953. Ecological monographs 3, 241-270; Maren et al. 2015. Journal of Arid Environments 121, 112-123). Names of subsections of Results and Discussion should be rethought and corrected. Now, e.g. the title of the section 3.2 is included in the title of 3.1, which is formed too general. As it can be seen from Appendix A, woody plants were inconsistently treated in the analyses. Once, they were really treated as woody plants, while in other cases were analyzed as herbs. Hence, the approach to “woody plants” should be clearly described in the “M&M” section. Even though, using PCA in Fig. 6 is not a mistake, the Authors should consider using RDA or CCA, which are more recommended and give more info, when both species as well as environmental variables are available for the ordination analysis.

 

Minor points:

l.13: the correspondence address suggests that X. Palomeque is the a corresponding author, not C.Q. Dahlik as indicated in l. 5

l. 16: spp written in italics should be changed for spp. (here and in the whole article)

l. 17: I suggest considering to change “evaluate” for “compare”, which, in my opinion, would better reflect the paper idea

l. 20: I do not like the term “woody composition” here, hence I suggest to change it, perhaps for more specifically “woody plant composition”. In fact “seedlings” were investigated in the study. Thus, the Authors could consider using this term in the paper.

l. 23: I agree that soil samples were taken, but the vegetation attributes were measured, not taken.

l. 26: change “is” for “was”

l. 29-30: The phrase “positively related to woody vegetation” should be changed for the more specific statement

l. 100: “and different types” should be changed for ”and in different types”

l. 106: please insert e.g. “for the study” after “chosen”

Figure 1: (i) “Km” should be changed for “km”; (ii) colours used for the elevation classes should be designed conversely to be consistent with the standard rules when land relief is shown with colours in maps: green for the lowest while orange/red for the highest elevations; (iii) I suggest inserting inscription “Azuay province” at its contour in the smaller map.

l. 112: The figure’s caption needs grammatical correction. Besides, I do not know which parenthesis the Authors mean. “C” and “G” should be changed for “TC” and “TG”, respectively.

l. 126-127: Using here the phrase “could be” is not professional. The accurate values or ranges should be given.

Table 1:

- caption: “Mean” should be inserted when relevant (e.g. mean tree height)

- there are mistakes in BA values given in the Table: 0.01-0.04 m2/plot (in fact the exact area – not “plot” - should be given here) is unreliable too small as for 16-22 years plantations.

- What kind of temperature do you mean in the column 1? Is it mean annual?

l. 141: Please specify what is the rotation cycle (cutting age) used for these plantations. I guess that the age is ca. 45 years, so the study concern only the first rotation cycle, besides not whole production cycle is included. Thus, again (see one of my moderate comments), the based on this study conclusions on the effect of the plantations on biodiversity should be in the paper softened.

What were the premises for (sub)plots location? Were they regularly or randomly established?

l. 159-160: Please describe how B-B scales were converted into values used subsequently for calculations.

l. 173-174: Please write more specific how the soil samples were collected. I mean if they were collected randomly in a plot or in other way.

l. 219-220: This sentence should be corrected. In the present form it is not fully consistent with the Figure 2b.

l . 221, l. 250: I could not find cover values in the App. A.

l. 224-225, l. 254-255: Captions of these figures are not self-explanatory. In the present form, a reader must guess (or check in the M&M section) that the graphs refer to median values etc.

Table 4:

- Why for the elevational classes mid values are given, but not the ranges? This should be consistent through the entire article.  

- shrub, vine, tree – Why is it given in the table foot?

l. 294: The (unnecessary in bold)

l. 294: Probably you mean “Figure 6 and Table 5”

l. 316: Probably you mean “Table 5”

l. 339-342: This paragraph is relevant to “Introduction” rather.

l .361: “herbaceous species richness and its cover” – needs correction

l. 440: two spaces

l. 446: a dot is lacking

l. 494 and Appendix below: Hb (habitat) in the head of a column does not reflect this column content

Author Response

Please see attachment

Author Response File: Author Response.docx

Reviewer 2 Report

Dear Authors,

Presented study addresses very important problem in plant ecology and forestry – effects of afforestation on páramo ecosystem regeneration and conservation. The research concern intentionally introduced Pinus patula. This species is spread beyond its native range and is commonly used in commercial forestry, mainly as a source of pulp wood.

The title captures the attention of the potential readers, however, I suggest to make some change (see specific comments). Essential, necessary details are presented in the abstract. The conceptual framework is explicit and justified. The research design is clearly described and data analysis procedures are clearly presented. Statistics are reported correctly and appropriately. The graphic presentations are sufficient to present results of study, however some changes in tables are recommended. 

Results revealed negative consequences of pine plantation for biodiversity, while conclusions are focused the positive role of planted forests in (some floral components) of páramo ecosystems restoration.

Authors clearly present negative consequences of pine planting (in results) as well as predict further problems connected with Pi clear cutting in the (near) future (forced by short- from 25 to max 45 years, Pinus patula rotation). However, the final message of the paper (presented mainly in paragraph 4.3 as well as in Conclusions) is that pine plantation support regeneration of native páramo vegetation.

In my opinion conclusions slightly hide the negative results of pine planting, and expose Pi positive role in páramo regeneration.

Authors inform us that Pi plots were compared with NG plots. However, plantations were established on grazed páramo. The most important question is does NG vegetation, destroyed (?) due to grazing, can restore under Pi canopy. Are there any information on soil properties and biodiversity of such (grazed) plots? Does and how biodiversity of grazed páramo differs from biodiversity of natural (not grazed?) páramo) and from Pi?  Add necessary information to Introduction. 

NG páramo  ˃ grazed páramo (decrease/increase? in biodiversity) > P. patula plantation

> ? further decrease in biodiversity of flora characteristic to páramo (negative impact of Pi) > ? increase in biodiversity (positive impact of Pi, and NG regeneration; pine planting justified).

Admittedly valuable native species (including 2 endemic plants) were noted in Pi, but did they re-colonized their natural localities after plantation establishment, or (what is more likely) they were remnants (especially woody species) of former NG vegetation?

It should be also noted and highlighted that from 13 endemic species, 5 occurred exclusively in NG.

In future studies I suggest to compare pine plantations of first and next rotations to recognize long-lasting consequences of pine introduction, and to estimate results of different silvicultural treatments in Pi which can be appropriate in Pi management to ensure the lowest loss in páramo biodiversity.

Specific comments:

Line 2-4: The main subject of study is natural regeneration of páramo vegetation, so I suggest to change the title from: What are the influencing abiotic and biotic factors on natural regeneration in pine plantations in the páramo ecosystem of Southern Ecuador? to: What are the influencing abiotic and biotic factors on natural regeneration of páramo ecosystem in pine plantations in Southern Ecuador?

In forestry ‘natural regeneration’ concerns mainly woody species, and  involves the establishment of a new forest from self-sown seed, coppice shoots, or root suckers etc. In current form of title, readers can expect data on seedling and saplings of Pinus patula or/and native Ecuadorian woody species, which occur and/or colonize pine plantation and/or NG.

Line 76-90. I suggest to move this paragraph after line 45 and to change the first sentence to: ‘Elevation is an important factor that shapes plant diversity in the páramo…’

Line 46: If foregoing suggestion will be accepted, change ‘…alter its biodiversity [7]’ to ‘…alter páramo biodiversity [7].’

Line 91 will be after current line 75: Change the order of first and second sentence;

On the other hand, there here is a lack of information of how soil properties under pine plantations impact the natural regeneration of both herbaceous and woody species. According 92 to Buytaert et al. [1], aAfforestation with pines, however, reduces soil organic matter contents as a result of a faster decomposition due to a lower soil water content [1], and there is a lack of information of how soil properties under pine plantations impact the natural regeneration of both herbaceous and woody species.

Line 98: Start new paragraphs  from Consequently, o’Our study addressed the following questions: …’

Line 128, table 1: remove ‘(Pi)’

Line129, and the Table 1: DBH abbreviation is usually used for Diameter at Breast Height, however DAP can also be used.

Line 142-144: Clearly inform readers on commercial purposes of Pinus patula introduction in area of Ecuadorian páramo. Add also information on foreseen rotation time.

Table 4: I suggest to present all endemic species in the paper in a way presented in Appendix A.1..

Did you collected data on the cover for every single species (Braun-Blanquet scale)? If yes, please add (in Table 4) and compare information on a mean cover of E species as well as on their constancy (% of plots where species occurred; for herbs 100% =3 x 20 = noted in all 60 subplots, and for woody species 100% =2x20= noted in all 40 subplots) in Pi and NG for every elevation.

Line 268: Abbreviations NG, Pi should be included in brackets after ‘natural grassland’, ‘pine plantation’

Line 269: Don’t use ‘average elevation’.

Line 376-377, 415. Correct the Latin names of families and species.

Line 415-418: Emphasize that alien species (I) occurred in majority or exclusively in Pi, therefore pine plantations can became sources of expansive/invasive exotic species for adjacent NG.

In Europe mentioned plants occur in anthropogenic semi-natural habitats (meadows and pastures) (Anthoxanthum odoratum, Holcus lanatus and Taraxacum officinale) or in degraded habitats as abandoned agricultural fields or forest clearings (all of them).

Line 450: Be very careful in underlining positive role of pine plantation in conservation of páramo biodiversity. Such massage can justify further páramo afforestation, and the loss in biodiversity of non-forest ecosystems is usually irreversible.

Line 494, Appendix A.1.: Hb – there is not a habitat, it is a life form (Lf); improve explanation.

With best regards,

Author Response

Please see the attachment

Author Response File: Author Response.docx