Abundance and spatial distribution of the main food species for mountain gorillas in the Virunga Massif, Rwanda

Providence Akayezu, I.C. van Duren, T.A. Groen, Cyril C. Grueter, Martha M. Robbins

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

The conservation of endangered species can benefit from a clear understanding of the quantity and distribution of their main foods. The population of mountain gorillas (Gorilla beringei beringei) living in the Virunga Massif of Rwanda, Uganda, and Democratic Republic of Congo has doubled in size since the 1980s, due to success in conservation efforts in and around their habitat. However, this increase in population size along with pressures on gorilla habitat raises concerns about spatial-temporal changes in the gorillas’ food plants. This study modelled the abundance and distribution of gorilla food species in the Virunga Massif. A total of 1050 vegetation recordings were collected on five plant species that are known to be frequently consumed by gorillas in one region of the Virungas, the Karisoke area. Two types of datasets collected along vegetation zones were combined: one with plant abundance expressed with Braun-Blanquet scores; and the other with abundance expressed as biomass. Moreover, ecological characteristics of locations where these species occur were extracted from satellite imagery. Analysis of variance and linear regression models were used to examine relationships between food species abundances and predictor variables. Subsequently, maps for the food species were created using boosted regression trees (BRTs). The abundance of species differed across vegetation zones, and the differences were statistically significant among vegetation zones with enough species observations. The accuracy of the BRTs indicated greater than random predictions (AUC > 0.65). This study shows the suitable areas for these gorilla food species and relevant ecological variables determining their distribution. The results provide insights into habitat occupancy by mountain gorillas, and help to design a baseline for monitoring changes in the abundance of gorilla food species under changing climate and anthropogenic pressure.
Original languageEnglish
JournalBiodiversity and conservation
DOIs
Publication statusE-pub ahead of print/First online - 2019

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Rwanda
Gorilla
mountains
spatial distribution
mountain
food
vegetation
habitats
Gorilla beringei
habitat
Gorilla gorilla
Democratic Republic of the Congo
Uganda
food plants
endangered species
variance analysis
satellite imagery
population size
analysis of variance
climate change

Keywords

  • ITC-ISI-JOURNAL-ARTICLE

Cite this

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title = "Abundance and spatial distribution of the main food species for mountain gorillas in the Virunga Massif, Rwanda",
abstract = "The conservation of endangered species can benefit from a clear understanding of the quantity and distribution of their main foods. The population of mountain gorillas (Gorilla beringei beringei) living in the Virunga Massif of Rwanda, Uganda, and Democratic Republic of Congo has doubled in size since the 1980s, due to success in conservation efforts in and around their habitat. However, this increase in population size along with pressures on gorilla habitat raises concerns about spatial-temporal changes in the gorillas’ food plants. This study modelled the abundance and distribution of gorilla food species in the Virunga Massif. A total of 1050 vegetation recordings were collected on five plant species that are known to be frequently consumed by gorillas in one region of the Virungas, the Karisoke area. Two types of datasets collected along vegetation zones were combined: one with plant abundance expressed with Braun-Blanquet scores; and the other with abundance expressed as biomass. Moreover, ecological characteristics of locations where these species occur were extracted from satellite imagery. Analysis of variance and linear regression models were used to examine relationships between food species abundances and predictor variables. Subsequently, maps for the food species were created using boosted regression trees (BRTs). The abundance of species differed across vegetation zones, and the differences were statistically significant among vegetation zones with enough species observations. The accuracy of the BRTs indicated greater than random predictions (AUC > 0.65). This study shows the suitable areas for these gorilla food species and relevant ecological variables determining their distribution. The results provide insights into habitat occupancy by mountain gorillas, and help to design a baseline for monitoring changes in the abundance of gorilla food species under changing climate and anthropogenic pressure.",
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year = "2019",
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Abundance and spatial distribution of the main food species for mountain gorillas in the Virunga Massif, Rwanda. / Akayezu, Providence; van Duren, I.C.; Groen, T.A.; Grueter, Cyril C.; Robbins, Martha M.

In: Biodiversity and conservation, 2019.

Research output: Contribution to journalArticleAcademicpeer-review

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T1 - Abundance and spatial distribution of the main food species for mountain gorillas in the Virunga Massif, Rwanda

AU - Akayezu, Providence

AU - van Duren, I.C.

AU - Groen, T.A.

AU - Grueter, Cyril C.

AU - Robbins, Martha M.

PY - 2019

Y1 - 2019

N2 - The conservation of endangered species can benefit from a clear understanding of the quantity and distribution of their main foods. The population of mountain gorillas (Gorilla beringei beringei) living in the Virunga Massif of Rwanda, Uganda, and Democratic Republic of Congo has doubled in size since the 1980s, due to success in conservation efforts in and around their habitat. However, this increase in population size along with pressures on gorilla habitat raises concerns about spatial-temporal changes in the gorillas’ food plants. This study modelled the abundance and distribution of gorilla food species in the Virunga Massif. A total of 1050 vegetation recordings were collected on five plant species that are known to be frequently consumed by gorillas in one region of the Virungas, the Karisoke area. Two types of datasets collected along vegetation zones were combined: one with plant abundance expressed with Braun-Blanquet scores; and the other with abundance expressed as biomass. Moreover, ecological characteristics of locations where these species occur were extracted from satellite imagery. Analysis of variance and linear regression models were used to examine relationships between food species abundances and predictor variables. Subsequently, maps for the food species were created using boosted regression trees (BRTs). The abundance of species differed across vegetation zones, and the differences were statistically significant among vegetation zones with enough species observations. The accuracy of the BRTs indicated greater than random predictions (AUC > 0.65). This study shows the suitable areas for these gorilla food species and relevant ecological variables determining their distribution. The results provide insights into habitat occupancy by mountain gorillas, and help to design a baseline for monitoring changes in the abundance of gorilla food species under changing climate and anthropogenic pressure.

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