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The amount of carbon stored in deadwood is equivalent to about 8 per cent of the global forest carbon stocks1. The decomposition of deadwood is largely governed by climate2–5with decomposer groups—such as microorganisms and insects—contributing to variations in the decomposition rates2,6,7. At the global scale, the contribution of insects to the decomposition of deadwood and carbon release remains poorly understood7. Here we present a field experiment of wood decomposition across 55 forest sites and 6 continents. We find that the deadwood decomposition rates increase with temperature, and the strongest temperature effect is found at high precipitation levels. Precipitation affects the decomposition rates negatively at low temperatures and positively at high temperatures. As a net effect—including the direct consumption by insects and indirect effects through interactions with microorganisms—insects accelerate the decomposition in tropical forests (3.9% median mass loss per year). In temperate and boreal forests, we find weak positive and negative effects with a median mass loss of 0.9 per cent and −0.1 per cent per year, respectively. Furthermore, we apply the experimentally derived decomposition function to a global map of deadwood carbon synthesized from empirical and remote-sensing data, obtaining an estimate of 10.9 ± 3.2 petagram of carbon per year released from deadwood globally, with 93 per cent originating from tropical forests. Globally, the net effect of insects may account for 29 per cent of the carbon flux from deadwood, which suggests a functional importance of insects in the decomposition of deadwood and the carbon cycle.

Recent records of the Rosalia longicorn beetle (Rosalia alpina) in Germany are only known from Baden-Württemberg and Bavaria. Bavaria has a special responsibility for the preservation of this species listed in Annex II of the Habitats Directive, due to the predominant number of German records in the federal state. This contribution compiles information on records, methods of mapping, and the evaluation of population size, habitat quality and possible impairments in Bavaria. Records of R. alpina in the Bavarian Alps range in a west-east expansion of about 210 kilometers from the Allgäu region to the Berchtesgadener Land. In north-south expansion, the occurrence is limited to a rather narrow band within the calciferous geological formations in the Eastern Alpine region. The core areas are located in calcareous beech forests (Seslerio-Fagetum). In Bavaria, the Rosalia longicorn predominantly breeds in the European beech (Fagus sylvatica), but also in sycamore maple (Acer pseudoplatanus), small-leaved lime (Tilia cordata), witch elm (Ulmus glabra), and whitebeam (Sorbus aria). There is a significant preference for sun-exposed, dry-standing deadwood both as habitats and as breeding substrate, but in open stands also lying deadwood in dry decomposition can be settled successfully. The study evaluates the conservation status of the populations of the Rosalia longicorn in Bavaria, and it outlines protection measures. [ABSTRACT FROM AUTHOR]