In functional ecology trait-based approaches are widely used. Gathering on-site measurements of traits can be very laborious, therefore, using traits retrieved from regional or global databases as proxies appears a convenient solution. However, many traits show intraspecific variability in trait values. Thus, using species mean trait values might lead to skewed patterns in traits and by that misinterpretations. The extent to which this is a problem probably depends on geographic scale, level of trait aggregation, type of process and habitat type. If we knew when it would be possible to use mean trait values of species from regional or global databases as an accurate proxy for on-site trait values of individuals, local-level experiments could be conducted without the often laborious task of measuring the functional traits of individual plants for each sampled community. Using data from two grassland sites, a salt marsh and a wet hay-meadow, we analysed the effect of species mean trait values retrieved from a regional database on the resulting trait structure of our plant communities. We compared on-site measurements from a 2 × 2 m scale with species mean traits aggregated per site (i.e. the habitat species pool), and those retrieved from a regional database (the LEDA trait database). We focused on the commonly used morphological plant traits canopy height, specific leaf area, and leaf dry matter content. Our results show that database values are more accurate in predicting the trait values in the habitat species pool as compared to the community mean traits aggregated per 2 × 2 m plots. The performance of database values also depends upon the trait and habitat type considered, as we show that traits with a high plasticity and traits in stressful habitats are being less accurately predicted. We can also explain why species trait means generally show a skewed representation of community traits as not only species composition, but also the individuals within species influence the community means. For studies focussing on processes mainly acting at the site scale (e.g. trait-environment relationships) traits retrieved from a regional database and filtered according to habitat will probably lead to reliable results. In contrast, studies focussing on processes acting at the plot scale (e.g. niche partitioning), require the additional effort of measuring traits on-site.
|Title of host publication||Proceedings of 56th Symposium of the International Association for Vegetation Science, 26–30 June 2013 Tartu Estonia|
|Publication status||Published - 2013|
|Event||Abstracts 56th Symposium of the International Association for Vegetation Science, Tartu Estonia - |
Duration: 26 Jun 2013 → 30 Jun 2013
|Conference||Abstracts 56th Symposium of the International Association for Vegetation Science, Tartu Estonia|
|Period||26/06/13 → 30/06/13|