The value of plant functional groups in demonstrating and communicating vegetation responses to environmental flows

Abstract

Summary This study compares the effectiveness of using plant species, genera, family or water plant functional group (WPFG) classifications for demonstrating differences in vegetation communities associated with inundation history. Vegetation surveys were undertaken annually for 5 years from 2007–2008 to 2011–2012 at 18 floodplain wetlands. These wetlands are from two geographically separate locations situated along the lower Murray River. Wetlands have different inundation histories and have received varied amounts of environmental water since 2004. All plant species recorded were classified into WPFGs. An inundation classification was determined for each wetland at each survey time based on inundation history and inundation status at the time of survey (wet or dry). This study found that plant species composition at individual wetlands is often unique with few species recorded across multiple wetlands. The use of WPFGs reduced the variability of plant communities between individual wetlands, between the two geographic locations and within inundation classifications. By reducing the variability between samples, broad trends in vegetation responses to different watering histories can be identified. Individual wetlands can develop completely different suites of plant species in response to the same watering regime, particularly when separated over large distances. This variability can reduce the confidence managers have in predicting the plant communities likely to develop in response to prescribed watering regimes. Adaptively applying knowledge gained from monitoring to different wetlands or wetlands in different geographical regions is also difficult if responses are highly variable. This study demonstrates that by classifying wetland vegetation into WPFGs the variability observed between samples can be reduced and the influence of floristic differences between individual wetlands and geographic locations can be negated or lessened. We discuss how the use of WPFGs can assist scientists and managers in demonstrating, predicting and communicating trends in vegetation community responses as a result of different watering regimes. The adoption and application of a consistent approach to the classification of plant species into WPFGs has the potential to enable responses and predictions to watering events to be made across broad spatial scales.

Riparian plant guilds of ephemeral, intermittent and perennial rivers

“…Other studies have used ‘habitat preference guilds’ such as wetland indicator groups that synthesise the combination of traits that adapt plants to different levels of water availability (Stromberg et al ., ; Goebel, Pregitzer & Palik, ; Laidig et al ., ). Such studies help us understand how non‐phylogenetic groups respond to hydrologic changes, such as shifts from perennial to intermittent flows, but the need to capture the causal mechanisms underlying habitat preferences and tolerances remains (Merritt et al ., ; Campbell, Johns & Nielsen, ). Traits that reflect productivity and growth rate, regeneration processes, storage and defence all are important when identifying suites of species adapted to riparian conditions (Hunt et al ., ; Aguiar et al ., ; Verberk, van Noordwijk & Hildrew, ).…”

Legacies, lags and long‐term trends: Effective flow restoration in a changed and changing world

“…Notwithstanding the multi-million dollar investments in monitoring, ecological responses to eflows in the Murray River have been inconsistent, site and taxon specific and sometimes difficult to detect (e.g. Campbell, Johns, & Nielsen, 2014;Vivian, Marshall, & Godfree, 2014;Zampatti & Leigh, 2013).…”

Large‐scale environmental flow results in mixed outcomes with short‐term benefits for a semi‐arid floodplain plant community

“…Furthermore, all of our community‐level metrics demonstrated either no change, or a net decrease, in taxonomic richness by the end of our study. These negative responses are likely to be associated with the terrestrialisation of the floodplain vegetation in the Hattah Lakes system due to long dry phases (Bino et al., ; Campbell et al., ; Colloff & Baldwin, ), and the adverse response of dry‐land taxa to prolonged inundation (Capon, ; Casanova & Brock, ; Nishihiro, Miyawaki, Fujiwara, & Washitani, ; Raulings, Morris, Roache, & Boon, ; Webb, de Little, Miller, & Stewardson, ). This was evidenced by the dominance of terrestrial dry and damp taxa in our study area, and the tendency for these groups to respond negatively to the flood, as well as the low abundance of amphibious plant taxa in this system.…”