Evaluation of plant functional types response to grazing and fertilizer levels in natural grassland

We report a study on a natural grassland experiment with the objective of finding optimal plant functional types (PFTs) for the description of vegetation response to levels of grazing (ungrazed, grazed) and fertilizer (with, without). The experiment was a split-plot design in randomized blocks, with three replications and the grazing levels in the main plots. Vegetation description was based on species composition and on 12 plant morphology attributes (life-form, growth-form, stem tissue type, leaf cross section, leaf texture, leaf dorsal epidermal surface, leaf ventral epidermal surface, spininess, leaf resistance, leaf width, plant height). Cover-abundance of species was visually estimated. By using a measure of congruence, multivariate analysis and randomization testing, implemented in software SYNCSA, an optimal subset of the attributes was found (plant height, spininess and leaf cross section) that when used to define PFTs composition could express vegetation response to grazing more clearly than species composition did. The same procedure applied for the vegetation response to fertilizer could not find an optimal subset among the 12 attributes evaluated.