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Open AccessArticlePost Publication Peer ReviewVersion 2, Approved

Assessment of Habitat Change Processes within the Oti-Keran-Mandouri Network of Protected Areas in Togo (West Africa) from 1987 to 2013 Using Decision Tree Analysis (Version 2, Approved)

1
West African Science Service Center for Climate Change and Adapted Land Use, Université Félix Houphouët-Boigny, 31 BP 165 Abidjan, Cote D’Ivoire
2
Laboratoire de Botanique et Ecologie Végétale, Faculté des Sciences, Université de Lomé, BP 1515 Lomé, Togo
3
Laboratoire de Zoologie et Biologie Animale, UFR Biosciences, Université Félix Houphouët-Boigny, 02 BP 1170 Abidjan, Cote D’Ivoire
*
Author to whom correspondence should be addressed.
Received: 16 January 2019 / Revised: 17 January 2019 / Accepted: 2 February 2019 / Published: 1 January 2020
Peer review status: 2nd round review Read review reports
Version 2, Approved
Published: 1 January 2020
DOI: 10.3390/sci2010001
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Version 1, Original
Published: 14 February 2019
DOI: 10.3390/sci1010009.v1
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Biodiversity conservation planning is highly important in the current context of global change. Biodiversity conservation can be achieved by understanding changes in land use at the landscape scale. Such understanding is needed to reverse the unprecedented pressure on natural resources that has been reported by many studies conducted on biodiversity conservation within the Oti-Keran-Mandouri protected areas. Land cover maps reflecting different dates (1987, 2000, and 2013) and depicting different management systems, with overall accuracy ranging from 73% to 79%, were analyzed to understand the processes that lead to habitat degradation within these protected areas. The nature of change, within a given land cover class, was determined by comparing land cover maps on different dates using a decision tree algorithm that compares the number of patches, their areas, and their perimeters at different time periods (T1 and T2). Specifically, two time-periods were considered for this analysis: 1987–2000 and 2000–2013. Croplands and settlements increased at an average of 108.13% and 5.45%, respectively, from 1987 to 2000. From 2000 to 2013, croplands gained from all other land categories and continued to increase at a rate of 11.77% per year, whereas forests and savannas decreased at an annual average rate by 5.79% and 2.32%, respectively. The dominant processes of habitat change from 1987 to 2000 were the creation of forests, dissection of savannas, attrition of wetlands, and creation of croplands. Meanwhile, from 2000 to 2013, there was attrition of forests, as well as attrition of savannas, dissection of wetlands, and aggregation of croplands. In general, from 1987 to 2013, natural habitats regressed and were replaced by croplands; forests, savannas, and wetlands decreased at an average annual percentage 5.74%, 3.94%, and 2.02%, respectively, whereas croplands increased at an average annual rate of 285.39% of their own area. Aggregation, attrition, dissection, and creation were the main habitat change processes identified for the overall period from 1987 to 2013. There was habitat loss in forests and savannas and habitat fragmentation in wetland due to attrition and dissection, respectively. Identifying and understanding habitat change processes would enable the taking of appropriate biodiversity conservation actions. View Full-Text
Keywords: land cover; landscape change; habitat fragmentation; conservation planning; Oti-Keran-Mandouri; Togo land cover; landscape change; habitat fragmentation; conservation planning; Oti-Keran-Mandouri; Togo
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Polo-Akpisso, A.; Wala, K.; Soulemane, O.; Folega, F.; Akpagana, K.; Tano, Y. Assessment of Habitat Change Processes within the Oti-Keran-Mandouri Network of Protected Areas in Togo (West Africa) from 1987 to 2013 Using Decision Tree Analysis. Sci 2020, 2, 1.

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1

Reviewer 1

Sent on 19 Jun 2019 by Javier Martínez-Vega | Approved with revisions
CSIC

In general terms, the research is very well developed. I think that this article has a great interest to be published in Sci, considering that this journal covers all research fields and that it welcomes case studies.

 

The manuscript describes the land uses-land cover changes that occurred in the Oti-Keran-Mandouri protected areas, in Togo, during the last 25 years. Despite having different figures of national and international protection (national park, Ramsar wetlands), this fragile region has been subject to environmentally worrisome dynamics, as result of demographic pressure and climate change. Using Landsat images from 1987, 2000 and 2013, the authors analyze the nature of land use-land cover changes, the habitat change processes and their consequences on landscape structure. The reduction of forest and savanna habitats and the fragmentation of wetlands are the most relevant processes. According to the results, the authors propose biodiversity conservation actions to those responsible for their management.

 

The contents are organized into the usual sections. The contents of each section are correct and follow a logical sequence. The references are abundant and valid, although some are old, especially those related to the “methods” section.

 

Although the methods, in themselves, are not original, they are correct and designed to solve a specific environmental challenge as well as to help managers. They are solidly supported by previous scientific studies. The "assessment of habitat change processes" subsection is very clear and interesting.


The results derive from the application of the techniques used. Will be very useful to the managers of the protected areas in the planning and decision-making processes. In the first reading, an explanation of what are the driving factors of land use-land cover changes and habitats is missing. However, after reading the "discussion" section, it is clear what are the factors that explain the processes that have occurred and are contextualized in the African continent and on a global scale.


The discussion section adequately complements the results. It is very complete and well documented.

 

Despite their interest, a minor revision is convenient to improve some formal and content aspects of the manuscript. Below, the following suggestions are proposed:

 

I recommend harmonizing the color of the savanna class in figure 4. The shade of green used in land cover map 1987 does not seem similar to the one used in the other two maps and in the legend. Also if possible, I suggest using some simplified cartographic base as the background of the tree maps.

The temporal evolution of the surface of settlements is surprising (figure 5). Usually, it is a temporarily irreversible category. In the discussion, the authors already explain the difficulty of discriminating this category with crops and, sometimes, with the savanna. However, perhaps, the authors can place more emphasis on this issue.

 On page 9, the first paragraph ("The net change in each land category ...") is confusing. According to Pontius et al. (2004), the net change = gains-losses. In addition, the authors indicate that the results of the net change are reported in table 4. It is not correct. This table contains the image classification accuracy (p.7).

On line 8 on page 9, the annual average rate (285.39%) seems very high. I suggest reviewing the data.

 At the end of line 9 of section 4.2 Land Cover Dynamics, I suggest adding the Dudley et al., 2018 reference: https://doi.org/10.1016/j.gecco.2018.e00424

In reference no. 4 (Karr 1994), replace "Landscale" with "Landscapes


Response to Reviewer 1

Sent on 11 Jul 2020 by Aniko Polo-Akpisso, Kperkouma Wala, Ouattara Soulemane, Fousseni Folega, Koffi Akpagana, Yao Tano

The slight change in color reflectance could be due to the mix of color that has highly changed from 1987 to 2013. All these maps are from the same ArcMAP project. Shapefiles, scale, color, legend are consistent.

The reviewer is right and the suggestion is correct. This issue about the accuracy in mapping and estimating land changes in heterogeneous landscapes in West Africa is still a debate among researchers. We would like to leave this idea as expressed but we are opened to any formulation.

The reviewer is right. The sentence was corrected accordingly. We would like to refer to the later image as reference of the calculation.

This rate is very high but that is the result we got. There is no mistake. Unfortunately human pressure has been incredibly high in the study area due to complex factors including the past bad management issues.

Dudley et al. 2018 was added as suggested.

The reference was updated

Reviewer 2

Sent on 12 Aug 2019 by Jesús Jiménez López | Approved with revisions
Marine and Environmental Sciences Centre (MARE)

The manuscript aims to describe and quantify the land cover dynamics and habitat change processes occurring at the OKM Network of Protected Areas, using satellite based land cover maps gathered in different periods of time. The sequential application of well-established remote sensing methodologies reveals that the region is experience an important degradation of their natural values (forests, savannas, and wetlands), especially due to agricultural expansion and the increasing impact of human settlements. Most spatial processes underlying the habitat changes occurring in the region were dissected using a decision tree and cross tabulation analysis, as described in the body of the research.

 

The manuscript provides an essential base line for land change dynamics within the OKM Protected Areas that can be used to foster effective management and target appropriate conservation actions.

 

Please find below suggestions that complement other reviewers’ comments and you might find useful to improve the overall quality of the manuscript.

 

 

Figure 1. Study area

 

I recommend working on the map in case you have the required data. The title (“Legend”) does not give any particular information and could be safety removed. Instead “Some localities”, use localities or something similar. Also, notice that while some layers are grouped by categories, other not related layers are mixed in between. I suggest making this separation clearer including an additional category (protected areas? ) or alternatively just remove the categories keeping the legend simpler. The mapping area is somewhat confusing. A careful selection of symbols, colors and patterns might help to better depict the study area. Also, the composition / layout could be improved. For instance, auxiliary maps could be positioned above the main map, so there’s more room to arrange everything. Keep an eye on your fonts, there’s room enough to position “BENIN” and “GHANA” horizontally. Also, choose font style wisely. I recommend you to check other similar maps on Internet.

 

Figure 6.

Y-axis label should be number of patches

 

Landsat images of 30-m spatial resolution acquired in 1987, 2000, and 2013 were downloaded for free (from where?). You might want to include the source or platform from where you get the images.

I suggest rephrasing the following sentence and briefly explain or cite the purpose of the reference data (e.g. interpretation, classification, validation…)

The reference data have been generated differently for each image. They were based on ground verification data for the recent image, while they were generated from the national topographic map..

You might find interesting to include the following output:

The output is a map where each land cover class is assigned the category of change that it is experiencing.

Also, I suggest that you plot or include in tabular form the most important change processes affecting each land category if possible, and not just the most predominant. This information can help determining what’s happening where and when.

The following sentence in the conclusion section is confusing to me, in the sense that it seems to indicate that climate change adaptation strategies are causing the degradation of these natural areas. Maybe I am missing something, but if that is the case, you should explain why.

The degradation has worsened due to implemented adaptation strategies to climate change that are mostly linked to land use change, such as recessional agriculture.

 

Response to Reviewer 2

Sent on 11 Jul 2020 by Aniko Polo-Akpisso, Kperkouma Wala, Ouattara Soulemane, Fousseni Folega, Koffi Akpagana, Yao Tano

All the suggestions are very good and Figure 1 is updated accordingly.

Y-axis label has been corrected.

The link of the platform is provided.

The sentence is rephrased. The reference data are needed for accuracy assessment.

It is true that presenting a map is very illustrative but here the map is not adding any other information apart from what is reported in Table 6. Land categories have the same extent for a given period as shown by figure 4 therefore we preferred to present the result in a table.

The change affecting each land cover category for a given period is reported in Table 6.

Yes, adaptation strategies (expansion of cultivated areas and recessional agriculture that is the cultivation of rivers’ bank) are degrading natural areas. That is exactly what we mean.

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