Teatime in the Serengeti: macrodetritivores sustain recalcitrant plant litter decomposition across human-modified tropical savannahs

Abstract

Background and aims Intensification of savannah land-use is predicted to negatively influence soil biodiversity and functioning such as litter decomposition by detritivores. Loss of macrodetritivores, particularly termites, may be problematic in drier savannahs due to the capacity of macrodetritivores to sustain litter decomposition. Here we investigate how human land-use and spatiotemporal rainfall influence the contribution of macrodetritivores to plant litter decomposition. Methods We measured decomposition using globally standardized litter: labile green and recalcitrant rooibos tea litter. The contribution of macrodetritivores to litter decomposition was determined through exclusion using meshed litterbags. Litter decomposition was determined in agricultural land, pastureland and wildlife protected areas during both wet and dry seasons and in mesic and wet rainfall regions across the borders of the Serengeti National Park, Tanzania. Results Macrodetritivores consumed recalcitrant rooibos and mainly avoided labile green tea litter. On average macrodetritivores enhanced recalcitrant litter decomposition by 22%, but litter mass loss varied across land-uses, typically being higher on agricultural and pastureland compared to wildlife protected areas, and was sustained during periods of water scarcity. However, we observed instances of higher decomposition of recalcitrant litter by macrodetritivores in wildlife protected areas. In contrast, litter decomposition by microbes and microdetritivores was more constrained by seasonal and regional water availability with a minor influence of land-use. Conclusion We found that moderate human-modification of savannahs is compatible with macrodetritivore litter decomposition. As savannahs become more intensely used by humans, raising ecological awareness among agropastoralist is required to ensure continued contribution of macrodetritivores to litter decomposition.

Risk of misinterpreting the Tea Bag Index: Field observations and a random simulation

“…Calculating the posterior distribution of a r − Mloss_R using the hydrolyzable fractions determined by Mueller et al (2018) caused the 0–5.3 percentiles of the posterior distribution of a r − Mloss_R to be lower than zero, Figure S2) at our limestone site, which was much smaller than the value using original protocol (Figure 2c). Second, the soil fauna might have preferably consumed rooibos tea and reduced its apparent S (Sundsdal et al, 2020; Teo et al, 2020), although the damage to the tea bags caused by soil fauna was nonsignificant at our limestone site. To obtain more definitive results, TBI‐based k and time‐series data‐based k (Mori, 2021; Mori, Ono, & Sakai, 2021) should be compared in additional laboratory incubation studies.…”

Leaf decomposition and flammability are largely decoupled across species in a tropical swamp forest despite sharing some predictive leaf functional traits

“…Two types of litterbags, both 16 cm × 18 cm in size but differing in mesh size, were used to partition the contribution of meso‐ and macrofauna vs microfauna and microbes only to decomposition. One litterbag type was double layered with an outer mesh size of 0.3 mm (composed of ethylene‐tetrafluoroethylene plastic) and an inner nylon layer of 50 μm (0.05 mm) aperture size to allow only microfauna and microbes (Smith et al ., 2018; Sundsdal et al ., 2020; Teo et al ., 2020). The second litterbag type was made using a 3‐mm aperture size polypropylene mesh and allowed litter meso‐ and some macrofauna (Lam et al ., 2021).…”

Termites are the main dung removals in a degraded landscape in Brazil

“…However, the evolutionary success of the Termitidae (the most diverse and numerous family of termites, called higher termites) is attributed to the loss of protozoans and the acquisition of specialized lignocellulolytic bacterial lineages that allowed diet diversification, including wood, grass, soil, litter, lichen, and fungi (Bourguignon et al, 2011;Brune and Dietrich, 2015). In tropical environments, termites are the main macrodetritivores, decomposing half of deadwood in rainforests and more than 30% of the litter in savannas (Veldhuis et al, 2017;Griffiths et al, 2019;Sundsdal et al, 2020).…”