Carbon stocks and dynamics at different successional stages in an Afromontane tropical forest

Nyirambangutse, Brigitte; Zibera, Etienne; Uwizeye, Félicien K.; Nsabimana, Donat; Bizuru, Elias; Pleijel, Håkan; Uddling, Johan; Wallin, Göran

doi:10.5194/bg-14-1285-2017

Cited by 48 publications

(51 citation statements)

References 96 publications

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“…The mean temperature during the study period was 14.6°C, mean daily minima and maxima were 11.4°C and 19.6°C, and rainfall was 1402 mm (Meteorological station location: 2°28′43″S, 29°12′00″E, 2465 m a. s. l. Nyirambangutse et al, ). September–November and January–March were the rainy seasons (monthly rainfall

> 100

mm), April–August was the major dry season (monthly rainfall < 100 mm), and December was also dry (<100 mm; Figure ).…”

Section: Methodsmentioning

confidence: 99%

Chimpanzee feeding ecology and fallback food use in the montane forest of Nyungwe National Park, Rwanda

Matthews

Ridley

Niyigaba

et al. 2019

American J Primatol

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Almost all primates experience seasonal fluctuations in the availability of key food sources.However, the degree to which this fluctuation impacts foraging behavior varies considerably. Eastern chimpanzees (Pan troglodytes schweinfurthii) in Nyungwe National Park, Rwanda, live in a montane forest environment characterized by lower primary productivity and resource diversity than low-elevation forests. Little is known about chimpanzee feeding ecology in montane forests, and research to date predominantly relies on indirect methods such as fecal analyses. This study is the first to use mostly observational data to examine how seasonal food availability impacts the feeding ecology of montane forest chimpanzees. We examine seasonal changes in chimpanzee diet and fallback foods (FBFs) using instantaneous scan samples and fecal analyses, supported by inspection of feeding remains. Chimpanzee fruit abundance peaked during the major dry season, with a consequent change in chimpanzee diet reflecting the abundance and diversity of key fruit species. Terrestrial herbaceous vegetation was consumed throughout the year and is defined as a "filler" FBF. In contrast to studies conducted in lower-elevation chimpanzee sites, figs (especially Ficus lutea) were preferred resources, flowers were consumed at seasonally high rates and the proportion of non-fig fruits in the diet were relatively low in the current study. These divergences likely result from the comparatively low environmental diversity and productivity in higher-elevation environments. K E Y W O R D Sdiet, eastern chimpanzee, high-elevation forest, seasonality

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> 100

mm), April–August was the major dry season (monthly rainfall < 100 mm), and December was also dry (<100 mm; Figure ).…”

Section: Methodsmentioning

confidence: 99%

Chimpanzee feeding ecology and fallback food use in the montane forest of Nyungwe National Park, Rwanda

Matthews

Ridley

Niyigaba

et al. 2019

American J Primatol

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“…Previous studies in Nyungwe montane rainforest have shown that it has higher net primary productivity and trees with a higher leaf N concentration and photosynthetic capacity compared to many other tropical montane forests [34,51]. Furthermore, a study on soil N dynamics in Nyungwe reported an open and leaky N cycle [71].…”

Section: Nutrient Limitationsmentioning

confidence: 98%

“…Overall, temperature decreases and precipitation increases with increasing elevation, but there is also an east-west gradient such that precipitation at a given elevation is lower further east ( Table 1). The dry season in Nyungwe is in July and August, while it may last from May to September and is more pronounced in the Arboretum [46,51].…”

Section: Sites Climate Species and Measurement Campaignsmentioning

confidence: 99%

“…The three-month period preceding and covering the measurement campaigns during wet and dry seasons was markedly warmer, drier, and exhibited higher VPD at the low A site compared with N1 and N2. Both temperature and precipitation were measured over several years with weather stations at three of the sites (A, N1, N2; [46,51]). At C and N3, only temperature and air humidity at 1.7 m above the ground were measured using small temperature mini-loggers (Model TinyTag Plus 2, Gemini data loggers Ltd., United Kingdom) during a period of six to seven weeks (September to November 2017) to allow for comparisons with the other sites.…”

Section: Sites Climate Species and Measurement Campaignsmentioning

confidence: 99%

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Climate Sensitivity of Tropical Trees Along an Elevation Gradient in Rwanda

Mujawamariya

Manishimwe

Ntirugulirwa

et al. 2018

Forests

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Elevation gradients offer excellent opportunities to explore the climate sensitivity of vegetation. Here, we investigated elevation patterns of structural, chemical, and physiological traits in tropical tree species along a 1700–2700 m elevation gradient in Rwanda, central Africa. Two early-successional (Polyscias fulva, Macaranga kilimandscharica) and two late-successional (Syzygium guineense, Carapa grandiflora) species that are abundant in the area and present along the entire gradient were investigated. We found that elevation patterns in leaf stomatal conductance (gs), transpiration (E), net photosynthesis (An), and water-use efficiency were highly season-dependent. In the wet season, there was no clear variation in gs or An with elevation, while E was lower at cooler high-elevation sites. In the dry season, gs, An, and E were all lower at drier low elevation sites. The leaf-to-air temperature difference was smallest in P. fulva, which also had the highest gs and E. Water-use efficiency (An/E) increased with elevation in the wet season, but not in the dry season. Leaf nutrient ratios indicated that trees at all sites are mostly P limited and the N:P ratio did not decrease with increasing elevation. Our finding of strongly decreased gas exchange at lower sites in the dry season suggests that both transpiration and primary production would decline in a climate with more pronounced dry periods. Furthermore, we showed that N limitation does not increase with elevation in the forests studied, as otherwise most commonly reported for tropical montane forests.

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“…Nyungwe National Park protects 1,020 km 2 of tropical montane forest in south‐western Rwanda. Nyungwe received 1,530 mm of rainfall and had an average daily temperature of 14.8°C in 2017 (Uwinka meteorological station: 2°28′43″S, 29°12′00″E, 2,465 m ASL; Nyirambangutse et al, 2017). The region experienced a major wet season from January to March, a long dry season from April to August, with a minor wet season from September to November and shorter dry season in December in 2017.…”

Section: Methodsmentioning

confidence: 99%

Chimpanzee ranging responses to fruit availability in a high‐elevation environment

Green

Boruff

Niyigaba

et al. 2020

American J Primatol

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Most primates experience seasonal fluctuations in the availability of food resources and face the challenge of balancing energy expenditure with energy gain during periods of resource scarcity. This is likely to be particularly challenging in rugged, montane environments, where available energy is relatively low and travel costs are high. Chimpanzees (Pan troglodytes) show extensive behavioral diversity across study sites. Yet, as most research has focused on low-and mid-elevation sites, little is known on how chimpanzees respond to periods of low fruit availability in harsh montane environments. We use focal follow and phenology data to investigate how fruit availability influences daily path length and monthly home range in chimpanzees living in Nyungwe National Park, a montane forest in Rwanda. Nyungwe chimpanzees decreased their daily travel distances during periods of fruit scarcity. However, this decrease in travel effort did not correspond with a decrease in foraging area. Instead, monthly homes ranges shifted location across the study period. Nyungwe chimpanzees occupy a relatively wide altitudinal range and the shifts in monthly home range location may reflect differences in the altitudinal distribution of food resources.Chimpanzee monthly diet was often dominated by one or two species and each of these species were confined to different elevation zones. One important species, Podocarpus latifolius, grew only at high elevations (2,600-2,950 m) and chimpanzees ranged at the altitudinal peak of their range for 2 consecutive months while feeding on this species. Thus, while high elevations are often thought to be harsh environments for primates, they can be an important part of a species' home range when they provide a refugium for densely distributed, important food species. K E Y W O R D S3D home range, chimpanzee, ecological constraints, montane forest, path length, seasonality

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Carbon stocks and dynamics at different successional stages in an Afromontane tropical forest

Cited by 48 publications

References 96 publications

Chimpanzee feeding ecology and fallback food use in the montane forest of Nyungwe National Park, Rwanda

Chimpanzee feeding ecology and fallback food use in the montane forest of Nyungwe National Park, Rwanda

Climate Sensitivity of Tropical Trees Along an Elevation Gradient in Rwanda

Chimpanzee ranging responses to fruit availability in a high‐elevation environment

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