Kaleka Agroforest in Central Kalimantan (Indonesia): Soil Quality, Hydrological Protection of Adjacent Peatlands, and Sustainability

Round 1

Reviewer 1 Report

See attached file

Comments for author File: Comments.pdf

Author Response

The authors thank reviewer 1 for the positive and constructive comments that helped us improve the manuscript, as detailed below:

Reviewer 1 comments and **Author responses

1. I have read the paper carefully and find the topic is interesting. **Author response: Thank you for the interest and the various suggestions to improve the manuscript. We considered all and followed most.
2. The research work is too descriptive. Formally, the article is well structured. The introduction provides sufficient information to understand the objectives. The results and conclusions are not consistent with the proposed objectives. Nevertheless, some paragraphs could be improved as suggested below. **Author response: We modified the wording of the objectives, so that they better align with the results presented and conclusions formulated
3. The title (Soil quality of wet kaleka agroforests protecting peatlands in Central Kalimantan, Indonesia) is not suitable. **Author response: We settled on: Kaleka Agroforest in Central Kalimantan (Indonesia): Soil Quality, Hydrological Protection of Adjacent Peatlands and Sustainability
4. Keywords: Agroforestry, Groundwater dynamics, Paludiculture, Peatland rewetting, Soil quality index, Tree diversity, Water balance. Change the keywords. Not use the words of the title as keywords **Author response: We settled on: Acid soils, Agroforestry, Fruit trees, Groundwater dynamics, Land suitability, Peatland rewetting, Restoration, Rubber (Hevea brasiliensis), Tree regeneration, Water balance
5. Line 16 of ‘kaleka’ agroforests. Later in line 96 . The term Kaleka refers, in the Dayak Ngaju tradition, to a previous settlement that has been abandoned but that continues to serve productive functions while being considered to be a sacred area in the “Kaharingan” traditional belief system and under communal customary land rights, often with commodity-specific resource sharing rule. It is difficult to understand the kaleka term, please rewrite this sentence. **Author response: we expaned the text, which now reads: “These agroforests are locally described as ‘kaleka’, or ‘awan uluh bihin’, a place where people lived in ancient times. It may have started as a hamlet where only 2-3 families lived, initially from opening swiddens in the neighborhood and allowing fallows to regenerate after a cropping phase of one or more years. The land directly around the houses became enriched with local fruit trees, and became sacred within the Kaharingan religious tradition, with graves of ancestors and tree-based burial sites of children. Trees with market potential, such as rubber (Hevea brasiliensis) were planted among the fruit trees. This resulted in a mixed and irregular cropping pattern. New land clearing took place beyond the Kaleka agroforests, protected by the local community as fruits can be enjoyed by all residents of the village, while commercial, market-oriented use has more restricted property rights [38]. “
6. Line 23-25. Kaleka, species-rich agroforests dominated by local fruit trees and rubber close to the river bank function well with high groundwater tables (up to -25 cm) compatible with peatland restoration. Please rewrite this sentence **Author response: yes, sentence is now split into parts
7. Line 84 In line with the three research questions plot-level data were collected on 1) the fluctuations of groundwater levels, 2) soil physical, chemical and biological characteristics, and 3) vegetation composition and other characteristics. Why repeat the purposes? **Author response: we removed the “In line with the three research questions” but not all readers may be as sharp as the reviewer and still remember the research questions at this point in the M&M…
8. Line 12. A description of the main geological features it is needed **Author response: we added “Kalimantan (the Indonesian part of Borneo island) is geologically part of the Sunda shelf, dominated by a quaternary geology that reflects fluctuating sea levels and climates in which peat soils could be formed and maintained, alternating with drier and more seasonal climates [[i]]. Pulang Pisau district is flat, with the slope on 81% less than 1%, and on 94% of the land less than 3%. As described in the semi-detailed soil map for the district [[ii]] The land area is dominated by interfluvial peat domes (Histosols) with 11.2% of the district peat influenced by rivers, and 47.9% ombrotrophic peat that depends on rainfall only, rather than river water. Most of the human activity has historically been in the alluvial deposits (Entisols) by and along a number of rivers (10.2% of the area) and in the coastal zone (13.5% plus 9.5% as fluvio-marine contact zone) with mangroves and associated pyrite concretions in the subsoil that can lead to acid sulphate soil reactions when drained. The remaining 7.7% of the area is tectonic in origin and tends to be used for settlements, such as the city of Palangkaraya; these soils are mostly Inceptisols.”
9. I suggest to improve the manuscript adding the present soil types according to Soil Taxonomy or FAO-UNESCO-ISRIC systems (Histosols?). **Author response: we have added further detail on the soils of the study area based on the semi-detailed soil maps.” According to the soil map [53] the soils closest to the river in Henda are Aeric endoaquepts, followed by Typic haplosaprist (sapric peat) and Hemic haplosaprists.”
10. Line 190. three monoliths. Please show some of them. **Author response: we added a new figure 4

11. Line 218-219. analyzed for Corg and pH(H2O) 219 pH(KCl) with standard lab methods [54]. Authors should provide more detail information about analytical procedures. **Author response: we added some further detail “for C_org (oxidizable matter in a soil sample based on the dichromate method developed by Walkley and Black method [[iii]]), pH(H₂O₎ and pH(KCl) (1:1 soil:fluid ratio with distilled water or 1 M KCl, respectively) with standard lab methods [[iv]].for C_org (oxidizable matter in a soil sample based on the dichromate method developed by Walkley and Black method [[v]]), pH(H₂O₎ and pH(KCl) (1:1 soil:fluid ratio with distilled water or 1 M KCl, respectively) with standard lab methods [[vi]].”
12. Line 236 2.5.4 Soil quality index. More details of the procedure to obtain the SQI it is necessary. **Author response: for full details the reader is referred to a number of primary publications, we only provide the basics here, including the equation used. “The various measured soil properties were combined into a ‘soil quality index’ based on a minimum data defined by [[vii], [viii]] through a Principal Component Analysis (PCA) on datasets for various crops, soil types and climates.”
13. Line 433 The data on groundwater dynamics, soil quality and tree species composition in kaleka agroforests that grow on the river bank with peat domes as their hinterland com plement a recent ethnobotanical study on the indicator and use values of plants in this landscape. What do you mean by… Please rewrite this sentence, this is not conclusion. **Author response: we rephrased the sentence: “The results of a recent ethnobotanical study on the indicator and use values of plants in kaleka agroforests that grow on the river bank with peat domes as their hinterland can now be corroborated by data on groundwater dynamics and soil quality. “
14. Line 439 In conclusions: The fruit agroforest functioned at an average groundwater level of -33 cm and measurements indicated that 55 percent of the time it exceeded the -40 cm level that is mandated for peatlands. The old rubber agroforest had an average groundwater depth -50 cm and demonstrated that rubber trees can function well under wet conditions. This form of land management through agroforest, developed as part of Dayak Ngaju traditions is thus compatible with the hydrological goals of rewetting peatland landscapes, understood as hydrological units and including non-peat soils. The low pH values (3.5 – 4) and high exchangeable Al concentrations indicate major constraints to common agricultural crops and suggest that major interventions such as liming would be needed to allow open-field agriculture to thrive. When peatlands are to be successfully restored, rewetting the peat domes will need to be accompanied by land uses around the peat dome that maintain high groundwater levels. Right now, this statement just being made without a supporting discussion is rather unsatisfying to me as a reader I wish those changes will contribute to improve your paper **Author response: thanks, we have developed text in the discussion section that prepares for this conclusion, that indeed is key to the policy relevance of the study.

1. MacKinnon, K., Hatta, G., Mangalik, A., Halim, H. The ecology of Kalimantan. Periplus Editions, Hong Kong. 1996.
2. Atlas peta tanah semi detail skala 1:50 000 [Atlas of semi-detailed 1:50 000 soil maps]; Kabupaten Pulang Pisau, Provinsi Kalimantan Tengah. Versi update 2016. Ministry of Agriculture, Jakarta. www.litbang.pertanian.go.id (accessed July 25 2021)
3. Walkley, A., Black, I.A. An examination of the degtjareff method for determining soil organic matter, and a proposed modification of the chromic acid tritation method. Soil Science, 1934, 37, 29-38.

[iv] Anderson, J. M.; Ingram, J. S. I. Tropical soil biology and fertility. A handbook of methods, 2nd edn. CAB. International, Oxfordshire, Wallingford.1993.  UK.

[v] Walkley, A., Black, I.A. An examination of the degtjareff method for determining soil organic matter, and a proposed modification of the chromic acid titration method. Soil Science, 1934, 37, 29-38.

[vi] Anderson, J. M.; Ingram, J. S. I. Tropical soil biology and fertility. A handbook of methods, 2nd edn. CAB. International, Oxfordshire, Wallingford.1993.  UK.

[vii] Vasu, D.; Singh, S. K.; Ray, S. K.; Duraisami, V. P.; Tiwary, P.; Chandran, P.; Anantwar, S. G. Soil quality index (SQI) as a tool to evaluate crop productivity in semi-arid Deccan plateau, India. Geoderma, 2016. 282, 70-79.

[viii] Rahmanipour, F.; Marzaioli, R.; Bahrami, H. A.; Fereidouni, Z.; Bandarabadi, S. R. Assessment of soil quality indices in agricultural lands of Qazvin Province, Iran. Ecological Indicators, 2014. 40, 19-26.

Author Response File: Author Response.pdf

Reviewer 2 Report

Line 263 - Shannon diversity index (H) was not calculated and presented in the result

Line 266-267 - 'Estimated aboveground biomass (Mg ha-1), AGBest = π * exp (-1.499+2.148 266 ln(DBH)+0.207 (ln(DBH))2 – 0.0281 (ln(DBH))3)' - equation has no wood density to use

 - BJ is not defined

Line 357 - 'DBH > 30 am (around 100 trees ha-1)' - 30 am should be '30 cm'

Section 3.3.3 from Line 376 - 381 is really short as you discussed about it more on the methodology part and didn't find supporting details.

Table 5 Aboveground Tree Biomass should be in Mg ha-1 rather than Mg ha

Line 377 - Species richness was not mentioned clearly in methodology and background

Line 380  - Shanon - Weiner  (H') was earlier defined as Shannon Diversity Index (H)

Author Response

The authors thank reviewer 2 for the suggestions  that helped us improve the manuscript, as detailed below:

Reviewer 2  **Author response:

Line 263 - Shannon diversity index (H) was not calculated and presented in the result. **Author response: It is in section 3.3.3

Line 266-267 - 'Estimated aboveground biomass (Mg ha-1), AGBest = π * exp (-1.499+2.148 266 ln(DBH)+0.207 (ln(DBH))2 – 0.0281 (ln(DBH))3)' - equation has no wood density to use **Author response: Thanks, corrected

BJ is not defined **Author response: Thanks, corrected

Line 357 - 'DBH > 30 am (around 100 trees ha-1)' - 30 am should be '30 cm' **Author response: Thanks, corrected

Section 3.3.3 from Line 376 - 381 is really short as you discussed about it more on the methodology part and didn't find supporting details. **Author response: Indeed – we added Figure 7 with the specific results for H’ index

Table 5 Aboveground Tree Biomass should be in Mg ha-1 rather than Mg ha **Author response: Thanks, corrected

Line 377 - Species richness was not mentioned clearly in methodology and background **Author response: definition added in 2.6.2 We mention highest and lowest values encountered.

Line 380  - Shanon - Weiner  (H') was earlier defined as Shannon Diversity Index (H) **Author response: Thanks, we harmonized the terms

A track changes' file with changes in response to both reviewer 1 and reviewer 2 was uploaded in response to reviewer 1

Round 2

Reviewer 1 Report

The authors have followed most of the recommendations given. Therefore, as a consequence of the changes and corrections incorporated in this new version, the scientific quality of the manuscript has considerably improved. However, in my opinion, before being published the manuscript needs some minor changes:

Line 171. Of the total area of the Mega-rice project, 32% consisted of fine-textured mineral soils with a peat layer (histic epipedon) of less than 40 cm thick, classified as sulfaquents (entisols with a tendency to become acid sulphate soils), fluvaquents, tropaquepts, dystropepts and hapludults. Please put in capital letter: Sulfaquents (Entisols with a tendency to become acid sulphate soils), Fluvaquents, Tropaquepts, Dystropepts and Hapludults.

Line 177. According to the soil map [53] the soils closest to the river in Henda are Aeric endoaquepts, followed by Typic haplosaprist (sapric peat) and Hemic haplosaprists. Please put in capital letter: Aeric Endoaquepts, Typic Haplosaprist  and Hemic Haplosaprists

I suggest to reduce the length of the conclusions. And it does not seem reasonable to include an author's quote in the conclusions

Author Response

Thank you for these further suggestions -- we have now followed the convention of capitalizing soil taxonomy terms.

We have also rephrased the opening sentence of the conclusion, to avoid the impression that this included a (self) citation.

We made some minor further edits, based on inconsistencies we spotted ourselves.