Effects on plant litter and soil chemistry –
Work package 3.4

Changes of abundance of species in the communities of organisms are followed by - or are consequences of – changed patterns of nutrient locations within the ecosystems. Changes in species composition generally also are reflected in alterations in tissue chemistry that translates into changes of litter and soil chemistry. In this work package, different ecosystem components (plants, litter, microbes and the bulk soil) are analyzed for treatment effects on total content of C, N and P and labile and inorganic fractions of the nutrients.

Plant, litter and soil samples for analyses of the pre-treatment nutrient content will be collected from the vegetation and the soil profiles described above. Subsequent sampling for treatment effects will be coordinated with the analyses of organism communities in this work package and with the work on C and nutrient dynamics in work package WP4 on ecosystem function. Furthermore, samples will be collected in winter and in the transition period between winter and spring and summer and autumn, when we expect particularly great changes in pool sizes due to re-distribution of the nutrients between the plant and microbial component of the system.

Plant tissue and litter chemistry will be analyzed (total C, N and P content, analyses of structural and non-structural carbohydrates in leaves by chemical fractionation into compounds that are known to affect litter decomposability, including lignin and cellulose). Single species of simple and complex carbohydrates have characteristic NIR reflectance peaks. Thus, we will analyze leaves and litter with NIR-spectrometry and use the chemical analyses to identify the NIR reflectance peaks (Richardson et al. 2004). A successful calibration will enable rough but non-destructively and cheap measurement of leaves and litter quality over time. Soil chemistry will be measured through extraction and analyses of soils for C, NH₄⁺, NO₃^-, inorganic P, dissolved and total microbial fractions of C and N and microbial P.

Soil chemistry measurements will be coordinated with measurements of soil water chemistry and leaching in WP4. The microbial biomass C, N and P will be determined by the chloroform fumigation extraction method and compared against the results of the determination of the active biomass by SIR, described above.