The concepts of traits, plant functional types (PFT), and functional communities are effective tools for the study of complex phenomena such as plant community assembly. Here, we (1) suggest a procedure formalising the classification of response traits to construct a PFT system; (2) integrate the PFT, and species compositional data to formally define functional communities; and, (3) identify environmental drivers that underpin the functional-community patterns.A species–trait data set featuring species pooled from two study sites (Eneabba and Cooljarloo, Western Australia), both supporting kwongan vegetation (sclerophyllous scrub and woodland communities), was subjected to classification to define PFTs. Species of both study sites were replaced with the newly derived PFTs and projected cover abundance-weighted means calculated for every plot. Functional communities were defined by classifications of the abundance-weighted PFT data in the respective sites. Distance-based redundancy analysis (using the abundance-weighted community and environmental data) was used to infer drivers of the functional community patterns for each site.A classification based on trait data assisted in reducing trait-space complexity in the studied vegetation and revealed 26 PFTs shared across the study sites. In total, seven functional communities were identified. We demonstrate a putative functional-community pattern-driving effect of soil-texture (clay—sand) gradients at Eneabba (42% of the total inertia explained) and that of water repellence at Cooljarloo (36%). Synthesis. This paper presents a procedure formalising the classification of multiple response traits leading to the delineation of PFTs and functional communities. This step captures plant responses to stresses and disturbance characteristic of kwongan vegetation, including low nutrient status, water stress, and fire (a landscape-level disturbance factor). Our study is the first to introduce a formal procedure assisting their formal recognition. Our results support the role of short-term abiotic drivers structuring the formation of fine-scale functional community patterns in a complex, species-rich vegetation of Western Australia.

The low availability of nutrients and water, and the regular occurrence of fire are the most pronounced natural disturbance considered as the principal drivers of vegetation patterning and dynamics in kwongan vegetation of Western Australia. To develop a plant functional type system explicitly reflecting these environmental challenges, we created a trait database describing various eco-morphological and functional aspects of the life history of the species sampled in both study areas. To this end, we compiled a soft-trait database featuring 1286 species indexed according to 21 binary traits scored from published taxonomic descriptions, our in situ studies, and inspection of lodged specimens (Western Australia Herbarium 2019–). Expert advice (see Acknowledgements) was sought with some specialised traits and syndromes. The functional traits used in this analysis and their states have been linked to the functional aspects of water relations, carbon balance, nutrition and fire, affecting growth, reproduction and/or survival are detailed to provide ecological relevance (see Table 1).

Table 1. Functional traits, their states and ecological relevance. The column Functional aspect indicates links of traits with water relations, carbon balance, nutrition and fire, affecting growth, reproduction and/or survival. Codes were produced for use in the PFT classification.

^APseudo-woodiness’ refers to trunks appearing woody composed from a mass of old leaf bases (as in Xanthorrhoea) held together by natural resin rather than true wood of dicot species. We have classified Kingia australis as ‘pseudo-woody. In this case the trunk (appearing ‘woody’) is formed by adventitious roots that originated in the top meristems

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Updated Trait Data Changes

• features the original 21 traits used in the manuscript,
• an additional 67 binary traits, and
• updated nomenclature for 49 species following the Western Australian Herbarium's November 2020 census