Consequences of Traditional Management in the Production and Quality of Copal Resin (Bursera bipinnata (Moc. & Sessé ex DC.) Engl.) in Mexico

Round 1

Reviewer 1 Report

The paper presents a comparison between the traditional and managed trees of copal resin, which makes, the current title does not perfectly fit. I suggest to change it and include the idea of the comparison of two management strategies and the impact to production and quality of copal resin, since this is presented in the whole paper.

The authors presented the study in a comprehensive manner, where details of methodology and results are nicely written and explained. The idea to compare the two management activities of copal resin trees is interesting.

Abstract

Line 31-33: inconsistency in writing species, genus (with italic)

Line 41-42: significantly higher? Please include p value

Text

Line 12 : Were the respondents’ age and working experiences referred to the traditional and managed tree farmers? If yes, can the information be separated?

Line 172: Were there any further specific criteria in collecting the samples? E.g. period of sample collection (e.g., during the first and second week, in the middle of production season, etc.). Did the researchers consider different species of resin, too?

Line 28-329 : p-value?

Line 367: .. a greater percentage of these compounds. Which compounds? Please spell it out.

Line 330: Related to my previous comments in Line 172, I suggest that the differences in the tree species can be somehow also shown in the results or discussed? E.g., what major species in traditional vs managed trees that have which compound of volatile/semi-volatile compound.

Conclusions:

As the research showed the better quality and quantity of managed copal resin trees over the traditional ones, the practice(s) from the managed trees that can be applied by the traditional farmers to improve the production can be mentioned again in this section.

Line 580: … Trees with favorable phenotypes that are managed in this agroforestry system maintain direct connectivity to surrounding forests, with important consequences at the landscape level, for the conservation of the TDF, its elements, and the environmental contributions it provides.

Please add some explanation about the importance of the trees for the landscape level and other environment contributions in discussion section.  

Author Response

Reviewer1
Comments and Suggestions for Authors
The paper presents a comparison between the traditional and managed trees of copal resin, which makes, the current title does not perfectly fit. I suggest to change it and include the idea of the comparison of two management strategies and the impact to production and quality of copal resin, since this is presented in the whole paper.
We appreciate the reviewer's suggestion. However, we would like to clarify that our study compared the quality of resin from wild populations and that from stands of trees selectively maintained in managed populations, both types of management are traditional management. The main purpose is to evaluate the consequences of traditional management involving selection of trees on the resin production and quality. This type of traditional management involves the management of wild trees with desirable characteristics, by planting stakes or seeds within agroforestry systems. We think the original title of the article is appropriate.

The authors presented the study in a comprehensive manner, where details of methodology and results are nicely written and explained. The idea to compare the two management activities of copal resin trees is interesting.
We appreciate the reviewer's opinion

Abstract
Line 31-33: inconsistency in writing species, genus (with italic)
The mistakes referred to were corrected in the Abstract (lines 31, 33, 45), and in the entire manuscript.

Line 41-42: significantly higher? Please include p value
Yes, we added the word "significantly" (line 41) and p-values for the 2017 and 2018 harvest seasons (lines 42-43).

Text
Line 129 : Were the respondents’ age and working experiences referred to the traditional and managed tree farmers? If yes, can the information be separated?
The two sentences referred to in the comment were separated to make the idea clearer (lines 173-175).

Line 172: Were there any further specific criteria in collecting the samples? E.g. period of sample collection (e.g., during the first and second week, in the middle of production season, etc.). Did the researchers consider different species of resin, too?
Details about sample collection are provided in the paragraph on lines 201-214 of the revised version of the manuscript. The selection criteria for the copal resin samples were also specified:
The first criterion was the diameter of the trunk. The copaleros only extract resin from trees with diameter at breast height (DBH) greater than 10 cm. The second criterion is the month of extraction. According to the copaleros, the extraction of resin should be carried out once the rainy season is well established. Therefore, traditionally all copaleros start the copal tapping season between the first and second week of August. The third criterion was that the trees to be tapped have a vigorous appearance and without evident diseases or pests
“Only the resin collected in Agave leaves (“copal en penca” or “planchita”) was considered in our quantification of resin yield. This was because this resin is the one that copaleros sell and to which they dedicate their greatest collecting efforts. The other types of resin, such as teardrop (lágrima), myrrh and gum (goma), were not considered in this study”. (lines 210-214)

Line 28-329 : p-value?
Thank you. The p value was added, and the reader are invited to consult Table 6 (line 438).

Line 330: Related to my previous comments in Line 172, I suggest that the differences in the tree species can be somehow also shown in the results or discussed? E.g., what major species in traditional vs managed trees that have which compound of volatile/semi-volatile compound.
Although resin from two Bursera species (B. bipinnata and B. copallifera) is extracted by people interviewed in the study area, our study focuses on the extraction of resin from B. bipinnata, since it is the most appreciated and preferred by the copaleros. Now, within the different types of B. bipinnata resin, we focus only on quantifying the production of what is locally known as "copal de penca" or "planchita" which is the most commercialized. Hence, estimating the differences in terms of volatile and semi-volatile resin compounds in both species of copal trees is beyond our current purposes of investigation. However, we appreciate the comment and believe that it may be a topic for future research.

Line 367: .. a greater percentage of these compounds. Which compounds? Please spell it out.
The names of the compounds (δ-cadinol, calemene, δ-cadinene, sabinyl acetate, α-pinene and β-amyrin), were added explicity in the sentence, to make the idea clearer (lines 475-476).

Conclusions:
As the research showed the better quality and quantity of managed copal resin trees over the traditional ones, the practice(s) from the managed trees that can be applied by the traditional farmers to improve the production can be mentioned again in this section.
The reviewer's suggestion was attended, and the following conclusion was added:
“This investigation revealed that B. bipinnata trees that receive some type of management produce a greater quantity of resin and of better quality in contrast to wild trees.” (lines 980-981).

Line 580: … Trees with favorable phenotypes that are managed in this agroforestry system maintain direct connectivity to surrounding forests, with important consequences at the landscape level, for the conservation of the TDF, its elements, and the environmental contributions. Please add some explanation about the importance of the trees for the landscape level and other environment contributions in discussion section.

In the Discussion section the following paragraph was added:
“In addition to the economic benefits of having greater spatial availability of the resource, at the landscape level the agroforestry practices documented for B. bipinnata allow connectivity between patches of wild vegetation, trees acting as windbreaks that conserve the soils, capture humidity, and reduce insolation (Figure 5). Additionally, isolated trees, particularly those of animal-dispersed species such as Bursera spp. [56,57], promote connectivity in agriculture-forest interfaces, as they attract animal dispersers operating as functional steppingstones across such landscapes [58].” (lines 521-544)

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript “Consequences of traditional management in the production and quality of copal resin (Bursera bipinnata (Moc. & Sessé ex DC.) Engl.) in Mexico” is well structured and organized. The study demonstrates the importance of resin management in a case study in Mexico, with a deep analysis of the quality of copal resin. The study of raisin management is timely, as there is growing interest towards the non-timber forest products, as one of the components of sustainable forest management.

The number of questions and comments need to be discussed:

• Please, clearly elaborate on the research question. What is the relevance and what is the state of the art of this study? Research objectives also needed.
• On the Figure 2 there are wild and managed places and trees, could you please explain what is the difference (e.g. property (who owns the forests and who has right to extract raisin), management differences, etc.).
• In the methods please describe the tree species composition and the dominated taxa (it was hard to understand if their growth only studied taxa or you choose the resin produced taxa)?
• There is a need to develop a subchapter on the governance of the resin extraction: regulations (who can extract, is it paid service, what are the forest management units, or is the Biosphere reserve who owns the forest? Economic influences and market (access to market, how important in economic terms the extraction is for locals from wild and managed forests)?
• There are short mentioning that Copal is used as a ritual “essential component”, could you please explain what meaning and beliefs does it have (based on your interviews).
• While talking about the cultural impotence of tapping activities, would be good to give some quotes about what locals say about the resin and its role in cultural life.
• Line 82 the use of resin is widely documented – elaborate and explain it a bit more.
• Line 446 According to the results, for bipinnata we found a linear relationship between the size of trees (expressed as height, cover, and DBH) and resin yield. – This is too obvious, the bigger and healthier tree the more resin it can produce. Explain how management influences the resin yield.
• Based on your finding on the species which produces the bigger quantity of resin and management type, please elaborate the recommendations for sustainable forest management in the area.
•  

Some small mistakes and corrections:

Line 33, Line 45  Bursera bipinnata need to be Italic.

Line 107 In the community studied live 298 people Better to say “In the studied community live 298 people”

Line 110 as a key seasonal livelihood? What do you mean by livelihood? Maybe key seasonal cash-generation or income generation?

Line 252 Is it coal management or copal management?

Author Response

Reviewer2

Comments and Suggestions for Authors

The manuscript “Consequences of traditional management in the production and quality of copal resin (Bursera bipinnata (Moc. & Sessé ex DC.) Engl.) in Mexico” is well structured and organized. The study demonstrates the importance of resin management in a case study in Mexico, with a deep analysis of the quality of copal resin. The study of raisin management is timely, as there is growing interest towards the non-timber forest products, as one of the components of sustainable forest management.

The number of questions and comments need to be discussed:

Please, clearly elaborate on the research question. What is the relevance and what is the state of the art of this study? Research objectives also needed.

We appreciate the reviewer's comment, we added the following paragraph, to clarify the relevance of our study:

“Clarifying these questions would allow assessing the contributions of traditional management of B. bipinnata to the sustainability of copal resin extraction. In turn, it would provide information on experiences that allow conservation of biological diversity of the tropical deciduous forest and the livelihood of people who are dedicated to this activity.” (lines 95-99).

Regarding the state of the art, this is established in the lines 75-95.

The objectives of the work are stated in the lines 113-116:

“This study aimed to document the traditional management and selection criteria for favoring good phenotypes of copal B. bipinnata in managed areas. We in addition analyze the effects of management and selection on the abundance of trees with preferred attributes (higher yield and quality of the resin), compared with that existing in wild populations”.

On the Figure 2 there are wild and managed places and trees, could you please explain what is the difference (e.g. property (who owns the forests and who has right to extract raisin), management differences, etc.).

This information is referred to in the Results section, specifically in point 3.2 (line 326-346).

Specifically, we mention that in the community of Los Sauces, both wild and managed copal trees occur within parcels owned by individual persons of the community, the parcels generally including both agricultural fields and forest areas. In this context, it is the parcel owner (the ejidatario, who is the right holder within the ejido structure), the person with the right to extract the resin or allow others to do so. Commonly, the ejidatario and their family members are who tap copal trees in their own parcel, and occasionally they allow other members of the community to extracting the resin.

In the methods please describe the tree species composition and the dominated taxa (it was hard to understand if their growth only studied taxa or you choose the resin produced taxa)?

We add a brief description of the dominant taxa of the Tropical Deciduous Forest. As we mentioned in the introduction, in the study area the copal resin is extracted mainly from two species: Bursera copallifera and Bursera bipinnata. Although B. copallifera trees are more common than those of B. bipinnata, the resin of the latter species is more appreciated due to its better quality and because it is sold at a higher price in the market.

The following paragraph was added (lines 127-139):

“TDF is characterized by the presence of small trees (4 to 10 m high, eventually up to 15 m), and abundant vines. In addition, most species lose their leaves for periods of five to seven months. A large number of the species produce exudates (resin or latex), and their leaves have fragrant odors when squeezed. The herbaceous stratum can only be appreciated in the rainy season. Some of the characteristic species of TDF are Amphipterygium adstringens (Schltdl.) Standl., Ceiba aesculifolia subsp. parvifolia (Rose) P.E.Gibbs & Semir, Conzattia multiflora (B.L. Rob.) Standl., Ficus petiolaris Kunth, Guazuma ulmifolia Lam., Lysiloma divaricata (Jacq.) J.F.Macbr., and Sapindus saponaria L. Among the species of the genus Bursera are Bursera aptera Ramírez, Bursera bicolor (Willd. ex Schltdl.) Engl., B. bipinnata, B. copallifera, Bursera fagaroides (Kunth) Engl., Bursera glabrifolia (Kunth) Engl., Bursera lancifolia (Schltdl.) Engl., Bursera linanoe (La Llave) Rzed., Calderón & Medina, and Bursera morelensis Ramírez can be found. In the study community, copalresin is only extracted from B. bipinnata and B. copallifera [32]. The resin of B. bipinnata is more appreciated due to its better quality and because it is sold at a higher price”.

There is a need to develop a subchapter on the governance of the resin extraction: regulations (who can extract, is it paid service, what are the forest management units, or is the Biosphere reserve who owns the forest? Economic influences and market (access to market, how important in economic terms the extraction is for locals from wild and managed forests)?

We appreciate the reviewer's suggestion, however, we think that addressing the issue of governance in the management of copal is beyond the purposes of this article. In fact, this topic deserves a complete study by itself. We believe that section 3.2 "Management strategies and practices” provides general information for some of the points raised here:

Regulations - The norms (NOM-009-RECNAT-1996), which is the regulatory framework for the use of resin species in Mexico, does not established defined technical criteria for most species including copal, and leave them to be the consideration of the forester in charge. Only for chicozapote (Manilkara zapota) and pines (Pinus pringlei; P. leiophylla; P. pseudostrobus) the norms have specific criteria.

“who can extract”? - The answer to this question is in the response above.

“is it paid service”? - The ejidatarios and their families are usually the ones that harvest and sell the resin.

“what are the forest management units,”? -  It refers to the sites sampled which are under management.

“is the Biosphere reserve who owns the forest?” -  In Lines 325-346 we explained that Los Sauces is a communal landholding (in the form of ejido), thus even if it is partially within the limits of the Sierra de Huautla Biosphere Reserve the land tenure is communal with individually owned parcels.

“Economic influences and market (access to market, how important in economic terms the extraction is for locals from wild and managed forests)?” - Analyzing market dynamics was outside the scope of this contribution, however it must be noticed that:

The community have been tapping copal resin for at least near a century, and the traditional regional fair of Tepalcingo has been the place where they generally sell all their production. Notably, since the community were able to extract the resin with authorization and management plans accredited by the federal environmental authorities, they have been able to charge 67% more per kg sold.

Copaleros can earn up to $700 to 2,000 US Dollars per harvesting season, which represent a key seasonal livelihood as it is conducted before maize is harvested.

Copaleros systematically harvest more the managed copal trees in the fields and agroforestry systems, while often less intensively, they also harvest copal trees growing in the forest.

There are short mentioning that Copal is used as a ritual “essential component”, could you please explain what meaning and beliefs does it have (based on your interviews).

The following paragraph was added (lines 404-408)

“The ritual use of copal resin is linked to syncretic rites such as the blessing of seeds, the request for rain and to be grateful for the crops. For various religious celebrations, copal resin is sold in markets and is an omnipresent element in church altars, but especially in the offerings of homes, both in rural areas and in the city. Also, the use of copal resin is associated with various ceremonies and rituals, for example, in divination and healing rituals, many of these of pre-Hispanic heritage.”

While talking about the cultural importance of tapping activities, would be good to give some quotes about what locals say about the resin and its role in cultural life.

We appreciate the reviewer's suggestion; however, our work is focused on the consequences of traditional management on the quantity and quality of copal resin. Addressing the cultural aspects of the extraction of copal was not part of this study and, therefore, we do not have enough information to deeply respond to the reviewer's suggestion. However, some cultural aspects of copal extraction are addressed in the section 3.4 (lines 404-418).

Line 82 the use of resin is widely documented – elaborate and explain it a bit more.

The sentence was modified:

“Use of copal resin has been widely documented, in particular for rituals and medicinal uses, past and present uses, species used, extraction processes and local nomenclature [24,27]” (lines 90-91).

Line 446 According to the results, for B. bipinnata we found a linear relationship between the size of trees (expressed as height, cover, and DBH) and resin yield. – This is too obvious, the bigger and healthier tree the more resin it can produce. Explain how management influences the resin yield.

We agree with the reviewer's observation, in the sense that this relationship is obvious. However, our intention when presenting these results was to contrast the resin yield of B. bipinnata trees with other species of the Burseraceae family, which are used in similar ecological contexts. As we mentioned in section 4.3 (line 689-694), B. bipinnata produces less resin when compared to other species of similar height and coverage (e.g. Boswellia papyrifera).

To clarify how management influences resin production, we add the following sentence:

“Thus, traditional management of B. bipinnata appears to act by eliminating those individuals that produce little resin and promoting very actively the propagation of individuals that produce large amounts of resin” (lines 684-686).

Based on your finding on the species which produces the bigger quantity of resin and management type, please elaborate the recommendations for sustainable forest management in the area.

The management plan of copal B. bipinnata currently exists (under a simplified version called Aviso de aprovechamiento), and basically documents, recognizes, and officializes the local practices. This document represents a relatively uncommon case where traditional ecological knowledge is taken as the blueprint for an official management plan.

However, as we pointed out in the discussion section (lines 860-868), evaluating the sustainability of copal resin extraction involves investigating others aspects about how the harvest affects some reproductive parameters (e.g. number of flower buds, flowers, fruits and seeds) comparing populations with and without copal harvest.

Some small mistakes and corrections:

Line 33, Line 45  Bursera bipinnata need to be Italic.

This observation was attended by correcting the name in the Abstract (lines 31,33,45), and in the entire manuscript.

Line 107 In the community studied live 298 people Better to say “In the studied community live 298 people”

We appreciate the observation; we made the change as fallows:

Los Sauces has a population of live 298 inhabitants, (line 140).

Line 110 as a key seasonal livelihood? What do you mean by livelihood? Maybe key seasonal cash-generation or income generation?

We rephrased the text as follows:

“Copal extraction has been widely carried out in the region for more than 100 years [26], and currently it is widely practiced as a key seasonal income that provides to people livelihood for the rest of the year” (lines 142-144).

Line 252 Is it coal management or copal management?

We appreciate the observation; we refer to the copal. The correction was done (line 354).

Author Response File: Author Response.pdf