Visual cover estimates from fixed plots are often used for monitoring changes in wetland vegetation. However, while it is recognised that estimates can vary due to observer bias, vegetation height and differences in plot placement between surveys, the effects of this variability on power to detect change are rarely assessed. We used vegetation survey data from shrub swamps in the Blue Mountains, Australia, to quantify variability in visual cover estimates from these sources and how it affects power to detect change between surveys, at the swamp scale, using paired-sample t-tests. Key variables included total cover of live green vegetation, bare ground and open water and the proportional cover of native vs exotic and/or terrestrial vs amphibious species, pooled across multiple 1 m(2) plots, per transect. Minimum detectable effect sizes for these variables ranged from a < 1 to 23 % change in mean cover per swamp, at the lowest possible level of replication (n = 3 transects), decreasing as replication increased. Our results highlight how useful pilot study data and power analyses are for assessing the adequacy of a monitoring methodology and sampling design, particularly the effects of sampling variability and replication on the magnitude of changes that can be detected.

Water regime is a primary driver of patterns in wetland vegetation composition. Differences in composition can be used as indicators of differences in water regime. We used vegetation point intercept data collected from 51 wetland monitoring plots in the Blue Mountains, south-eastern Australia, to determine which of three indicator group classifications, growth forms, water plant functional groups (WPFGs) or wetland indicator categories (WICs), demonstrated the most consistent differences between vegetation communities from plot sample groups differing in location (wetland edge or core) and surface water availability (typically inundated or damp). PERMANOVA tests showed significant differences between core and edge plot communities analysed by growth form or WIC relative frequencies, but only when tree canopy data (higher in edge plots, which were abutting woodland) was included. Significant differences in communities (PERMANOVA, p <= 0.02) were detected between inundation categories for all classification methods when tree data were included, but not for WIC data when tree data were excluded. Overall, ordination plots and ANOSIM R values showed the most consistent community-level differences (least overlap in sample groups) between inundation categories when data were classified by WPFGs, followed by growth forms. ANOVA tests on individual indicator group relative frequencies showed that WPFG classification provided the most indicator groups differing significantly in relative frequency between inundation categories, with these groups also collectively comprising a much higher proportion of the total vegetation recorded per plot than the growth forms or WICs that differed between categories. (C) 2015 Elsevier B.V. All rights reserved.

This pilot study of the rare Pagoda Rock Daisy (Leucochrysum graminifolium) in the western Blue Mountains of New South Wales (Australia) proposes a simple survey method combining timed meander and grid-cell survey design to improve the survey effort required for monitoring of species growing in remote and/or inaccessible field locations. Where Pagoda Rock Daisies were known to be present, detection time was both rapid and effective (mean of 4.9min for each 1ha grid). Notably, the total survey effort remained constant for all grids, even though Pagoda Rock Daisies were unevenly distributed in the landscape (approximately 17min/ha). Ultimately, the time required to traverse the landscape was deemed to be the primary limiting factor affecting survey effort. The application of this method is not restricted to challenging locations such as cliff edges; this method could be scaled according to the landscape or organism under investigation, providing a rapid method for surveying and monitoring rare, introduced or other plants from a site-based scale to a broader geographic area.

Effective monitoring requires clear questions and a well-designed sampling regime. However, objectives often evolve over time which can render the initial sampling design ineffective. Using a vegetation monitoring program employed in Newnes Plateau Shrub Swamps, Australia, as a case study, we examine a sampling design based on small numbers of 400 m(2) plots to assess if it can meet the stated monitoring objectives of detecting significant changes in number and abundance of species per wetland. To determine this, we intensively sampled four monitored wetlands using randomly distributed 4 m(2) plots to obtain representative estimates of species composition and abundance. The 400 m(2) plots captured 91 % of the common species and a similar proportional distribution of life-forms as found in the 4 m(2) plots, but missed 62 % of the sparse species found in 4 m(2) plots. Insufficient replication of 400 m(2) plots made detection of statistically significant changes at the swamp scale difficult or impossible. Our review showed the weak sampling design was contributed to by 1) an initial lack of clearly stated management triggers and 2) changes in monitoring objectives and triggers over time, without revising the sampling design. We highlight the need for an adaptive approach to monitoring.

Network theory in ecology has been central to understanding species co‐occurrence patterns, specialization and community stability. However, network theory has traditionally focused on the ‘higher’ trophic level where exploitation of network ‘partners’ (i.e. individual interactions in response to resource availability) have remained underappreciated. In this study we tested how clumping and host availability influenced mistletoe–host interactions in a semi‐arid woodland, central Australia. We used a hierarchical approach that evaluated individual interactions by modifying the traditional randomization technique to simulate clumping and host exploitation. Using published literature we then compared our results with mistletoes from other genera. We found that mistletoes clump on fewer trees than predicted, even though interaction strength was no different from random expectations, and we found no evidence that common trees were heavily infected as predicted by the host availability hypothesis. The rate of host exploitation (measured as the proportion of trees infected) in semi‐arid Australia is similar to that for mistletoe genera in other parts of the world. We hypothesize that specific host trees act as a focal point for infection that facilitates the spread and overall population size of mistletoes. Overall our results indicate that resources, such as the number of trees in a mistletoe network, are less important than clumping of individual plants. We suggest that exploitation of available resources may play a similar role in other networks that extend beyond antagonistic relationships such as parasite or herbivore interactions.