Successional trends in Floristic Quality

Abstract

Summary1. Simple, conservation-relevant, plant community measures are sought by resource managers. In this context, the use of Floristic Quality Assessment (FQA) has increased exponentially over the past 30 years. FQA measures a habitat's Floristic Quality and conservation value by summarizing the relative anthropogenic disturbance tolerances of its plant species (i.e. their Conservatism). However, despite their widespread use in research, restoration and conservation work, the behaviour of FQA values in communities during succession is not understood. 2. We analysed FQA values in 10 old fields over 50 years of unaltered succession. We determined whether Floristic Quality followed a predictable increasing successional trend, assessing four specific predictions: (i) FQA values will follow an asymptotically increasing, rather than peaked or linearly increasing trajectory; (ii) field initiation treatments (abandoned as hayfield or cropfield) will not lead to long-term differences in FQA values; (iii) trajectories will be consistent regardless of the particular species composition of fields and (iv) trajectories will be robust to common variations in FQA metric formulations (non-native species, varied spatial scale). 3. In all cases, a negative exponential rise to an asymptote best described FQA value trajectories over time. Field abandonment treatments did not affect FQA value trajectories. Furthermore, trends were consistent among fields despite differences in species composition among fields. Overall, the results suggest a predictable, deterministic path for FQA values over the early-to mid-successional timeframes studied. 4. Synthesis and applications. Understanding the temporal behaviour(s) of Floristic Quality is necessary for setting realistic restoration goals, evaluating habitat recovery and adapting management to achieve high conservation value natural areas. By illustrating the temporal consistency of Floristic Quality metrics during succession, this article demonstrates the robustness of FQA for such uses. The FQA value trajectory described here also establishes a background trend model for expected values in recovering habitats, which will allow for the assessment of an individual habitat's progression relative to the background trend. Such comparisons en masse will highlight the constraints of greatest importance to community-level Floristic Quality restoration. For example, FQA values in this study were ultimately limited by Conservative understorey plant re-establishment from adjacent old-growth forest. As this is not unlike species recovery patterns observed in other habitats, it suggests that restoration practitioners would do well to focus on Conservative species.

Plant‐soil feedbacks as drivers of succession: evidence from remnant and restored tallgrass prairies

“…CCs indicate a species' dependence on natural areas relatively undisturbed by anthropogenic activities (Swink and Wilhelm 1994), and in our region these values are correlated with the successional stage of the plant species (Spyreas et al 2012). Correlation coefficients were also used to test the relationship between plant-soil feedback and successional stage of each plant species.…”

Floristic Quality Assessment: a critique, a defense, and a primer

“…Floristic Quality Index is the product of Mean C and the square root of the area's plant richness. Note that non-native species may or may not be included in either equation, with similar performance either way (Spyreas et al 2012). By using them, only two pieces of information are needed to calculate an area's FQA value: a plant species list and the published C values for those species.…”

“…10; Spyreas et al 2012). In younger habitats (where succession is proceeding rapidly), site scores will vary with the habitats age.…”

“…Figure based onSpyreas et al (2012). A timeline of the floristic quality score within a New Jersey (USA) farm field over five centuries.…”

Testing a rapid Floristic Quality Index on headwater wetlands in central Pennsylvania, USA

“…Plants with high C values have a high fidelity to specific habitat types where disturbance is minimal while plants with low C values are generalist species that are found in a wide variety of habitats and disturbance regimes. FQA metrics have been shown to be robust to successional changes (Spyreas et al, 2012), natural temporal and spatial variability (Rooney and Rogers, 2002;Bourdaghs et al, 2006;Bried et al, 2013;Euliss and Mushet, 2011), and taxonomic turnover (Deimeke et al, 2013).…”