Forests make up the major percentage of terrestrial ecosystems and woody debris is recognised as an important long-term pool of forest carbon [29]. Despite being key to forest productivity, the understanding of how saproxylic organisms affect wood chemistry and organic matter stability during wood decomposition is still limited (see Refs. [47,50]. Among saproxylic insects, beetles make up the biggest part of saproxylic diversity and are primarily responsible for the mechanical breakdown of woody material [4], both directly, by tunnelling and feeding, and indirectly, through symbiotic relationships with fungi and other microorganisms that humify wood [45]. Many studies have shown increases in nutrient concentrations, especially nitrogen (N) and phosphorus (P), as wood decomposes [48]. A higher concentration of P and N than in surrounding soils was found in fresh earthworm casts [22], in freshly constructed termite mound materials [27], and in nests of wood ants [8]. Also, higher concentration of N and P than that of wood has been found in faeces of humivorous cetonid beetle larvae Pachnoda ephippiata [24,25], and in the faeces of the wood-feeding scarabaeid beetle larvae Osmoderma eremita [18] and Cetonia aurataeformis [31]. Moreover, numerous farmers from Africa, South America and Australia have long recognised the benefits of insects such as termites to crop production [48].