Recent decline in vegetative regeneration of bamboo (Yushania alpina), a key food plant for primates in Volcanoes National Park, Rwanda

Abstract

The African montane bamboo Yushania alpina provides both habitat and food for many species in the Albertine Rift region. In Volcanoes National Park (VNP), Rwanda, it is especially important as a key food resource for the Endangered mountain gorilla Gorilla beringei beringei and Endangered golden guenon Cercopithecus mitis kandti. We examined temporal and spatial variation in bamboo shoots regeneration and consumption by primates, monitored between 2013 and 2018 in 82 16-m2 plots located along transects in VNP. Our analyses revealed a decline in vegetative regeneration of bamboo in recent years, which is mirrored by a decline in bamboo shoot consumption by primates; but an increase in proportional intake. Local declines in regeneration are potentially due to high intensities of herbivory, decreased amounts of rainfall during growing seasons, and natural processes that form part of the life cycle of bamboo. Moreover, spatial variation in bamboo regeneration can be explained by elevation, as well as by stand-level variation in soil acidity, vegetation density, and the density of dead bamboo culms. We discuss the potential mechanisms underlying observed temporal and spatial variations and outline possible effects of a decline in bamboo regeneration for primates and other aspects of biodiversity in VNP.

High flexibility in diet and ranging patterns in two golden monkey (Cercopithecus mitis kandti) populations in Rwanda

“…In contrast, in group M which was at higherelevation range, the availability of bamboo shoots was the greatest during the long rainy season (March-May). These findings largely match elevational differences in bamboo regeneration intensities reported in a longterm study in VNP, which revealed that bamboo phenology depends on elevational gradient (van der Hoek et al, 2019). Future studies should investigate the extent of temporal and spatial dietary variation within this population by including more groups and determine how spatial differences in bamboo shoots affect monkey reproduction patterns.…”

“…Like golden monkeys, most large mammals such as the mountain gorillas (Gorilla beringei beringei), African elephant (Loxodonta africana), buffaloes (Syncerus caffer), bush buck (Tragelaphus scriptus), and black fronted duiker (Cephalophus nigrifrons) of the Virunga massif feed on bamboo shoots when available (Plumptre, 1991;Sheil et al, 2012). Given that the gorilla population has been increasing as well as possible increases in other large mammal populations (Granjon et al, 2020;Hickey et al, 2019), we encourage research focusing on interspecific feeding competition in VNP, especially involving bamboo shoots.…”

“…In addition, evidence of an ongoing decline in bamboo regeneration possibly due to the proliferation of herbivores in the region, or to climate change, are projected to affect the golden monkeys in the near future (Ayebare et al, 2018;Hemp, 2006;van der Hoek et al, 2019). The decline in bamboo availability may lead golden monkeys to expand their range and time spent outside the park boundaries to feed on crops such as carbohydrate-rich potatoes, as is already observed in group K. In VNP, golden monkeys are already considered the second most impactful species foraging on crops after forest buffalo (Mispiratceguy, 2019).…”

Growth response of Dendrocalamus asper on elevational variation and intra-clump spacing management

“…The result is quite different from previous research, which stated that the high temperature could stimulate growth and low temperature would inhibit the growth (Banik 2016). Several research proved that elevational variation would affect bamboo growth and the lower elevation provide a greater growth rate on Yushania alpina (Hoek et al 2019) and Chusquea (Clark et al 2015). In addition, according to various species of bamboo, each species has a favorable environmental requirement, such as Chimonobambusa utilis which is optimum on 1.500-2.000 m asl.…”

Distribution and conservation status of the golden monkeyCercopithecus mitis kandtiin Rwanda

“…Golden monkeys may also be negatively affected by climate change. A study in Volcanoes National Park reported a decline in bamboo regeneration, possibly the result of an overall decrease in rainfall in the Virunga region (van der Hoek et al, 2019). A simulation study focusing on the Albertine Rift predicted a decrease in the extent of habitats preferred by endemic species, including golden monkeys, because of climate change in the coming 6 decades (Ayebare et al, 2018).…”