Succession in abandoned fields: Chronosequence data verified by monitoring of semi-permanent plots

Questions

Is there a similarity between successional patterns in abandoned fields identified (a) through analysis of differently aged sites examined at one point in time (chronosequence) and (b) those derived from a limited set of semi-permanent plots? What is the rate of succession on dry and mesic abandoned fields and how is the participation of different functional groups changing during succession?

Location

Bohemian Karst, the Czech Republic, Europe.

Methods

This study utilises data collected from dry and mesic abandoned fields between 1975 and 2019. A data set of 129 chronosequence vegetation samples (54 dry and 75 mesic plots) and 26 samples from six semi-permanent plots (11 dry and 15 mesic) with different repetitions were analysed. Plot age (since abandonment) varied from 1 to 91 years for chronosequences and up to 99 years for semi-permanent data. Moreover, we compared the rate of succession between dry and mesic series using Bray–Curtis dissimilarity. We used a generalised linear mixed model to study the relationship between the cover of different functional groups and the age of abandoned fields.

Results

The successional patterns observed on abandoned fields were consistent between the chronosequence and semi-permanent plots. Both on dry and mesic fields, the early stages of succession transitioned from open annual to perennial herbal vegetation. In mesic fields, the succession led to woodland stands within approximately 25–30 years. Conversely, succession slowed down in dry fields and has persisted for several decades in a stage dominated mostly by perennial graminoids accompanied by scattered shrubs and trees. The trends detected with the chronosequence approach for the different functional groups corresponded to those found in semi-permanent dry and mesic series plots.

Conclusions

The plots using a chronosequence approach can reliably reveal general successional patterns comparable to those obtained from semi-permanent plots. Observing a higher number of plots at one time may better illustrate the variability of succession at the landscape scale than a detailed, long-lasting study of a low number of semi-permanent plots. In the studied area, the dry abandoned fields host a long-persisting non-forest state of succession under the current climatic conditions, while succession in mesic abandoned fields continues further towards woodland.