Nutrition of Douglas-fir in four different regions of the Czech Republic

Soil properties and foliar chemistry of Douglas-fir stands were evaluated in four regions with historical cultivation of this introduced species in the Czech Republic. All the localities are on acidic sites with pH (KCl) ranging between 4 and 5, low in concentrations of base cations particularly at the soil depth between 10 and 40 cm and also low in phosphorus. Sufficient to increased content of nitrogen and, on the other hand, the deficiency of phosphorus, potassium and occasional deficiency of magnesium were found in foliage. Studied Douglas-fir stands are apparently proximate to the acidic limit of convenient site conditions, however, neither the foliage discoloration nor the growth suppression has been observed. Sensitive management to ensure the nutritional balance sustainability is proposed.

Variably hungry caterpillars: predictive models and foliar chemistry suggest how to eat a rainforest

A long-term goal in evolutionary ecology is to explain the incredible diversity of insect herbivores and patterns of host plant use in speciose groups like tropical Lepidoptera. Here, we used standardized food-web data, multigene phylogenies of both trophic levels and plant chemistry data to model interactions between Lepidoptera larvae (caterpillars) from two lineages (Geometridae and Pyraloidea) and plants in a species-rich lowland rainforest in New Guinea. Model parameters were used to make and test blind predictions for two hectares of an exhaustively sampled forest. For pyraloids, we relied on phylogeny alone and predicted 54% of species-level interactions, translating to 79% of all trophic links for individual insects, by sampling insects from only 15% of local woody plant diversity. The phylogenetic distribution of host-plant associations in polyphagous geometrids was less conserved, reducing accuracy. In a truly quantitative food web, only 40% of pair-wise interactions were described correctly in geometrids. Polyphenol oxidative activity (but not protein precipitation capacity) was important for understanding the occurrence of geometrids (but not pyraloids) across their hosts. When both foliar chemistry and plant phylogeny were included, we predicted geometrid–plant occurrence with 89% concordance. Such models help to test macroevolutionary hypotheses at the community level.