Insect Biodiversity and Biomass in a Forested Region in Belgium: A case study in Bosland, Limburg
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Insects, being the first in the food chain, form a perfect animal group to estimate the vitality of an ecosystem. Their diversity and abundance could have tremendous impact on plants and other animals living in the ecosystem. Good research on insects requires using the best available methods. In this study I used a generalized linear mixed-effects models (GLMM) approach to model and evaluate three different methods of calculating insect biomass: dry insect biomass, wet insect biomass and insect biomass obtained from a length-weight power function. Results show that the use of oven dried insect biomass is most accurate with a low opportunity for human error and less uncertainty than the other methods. Most apparent differences are the way of gathering these data. Using length-weight regressions, although easiest to calculate, requires insect identification to the species level, making it time consuming in comparison to research that does not require specific species data. This research may help further research in gathering valuable data for analysis of insect biomass, by making a usable model to compare wet and dry insect biomass. This study aimed to evaluate the present biomass and biodiversity in different habitats within Bosland, a forested area in the north of the Limburg province, Belgium, focusing on both Nepomorpha (true water bugs) and Carabidae (ground beetles). Insect biomass declined for both groups from 2012 till 2020. Although uncertain, these results are concerning when looking at the broader picture of climate change and the effects these declines might have on other animals in the ecosystem. Nepomorpha diversity was found to be similar between different habitats, but high abundances of animals were captured in dune habitats, suggesting that this habitat may be used as a ‘highway’ to travel to a more suitable habitat. Carabidae biodiversity was highest in the valley and farmland habitats, although highest species richness was found in dune habitat. Rarefaction curves show that further research is needed, as asymptotes are not reached. Further research is warranted to get a better estimation of the actual insect biomass decline over the years. I suggest including and modelling with weather data and adding the amount of moonlight. Looking at insect turnover in the different habitats could give more insight in the changes in insect diversity through time. Next to these, development of length-weight regressions for European insects could enhance and simplify the estimation of insect biomass in studies looking at both insect diversity and biomass.