Summary1. Plant invasions are predicted to accelerate in a world with increased anthropogenic disturbance. Non-native species pre-adapted to these disturbances may especially be poised to invade novel communities. Conservation managers therefore need predictions of how to alter disturbances to maximize the persistence of native biodiversity. 2. We tested a multivariate hypothesis about the causal mechanisms underlying plant invasions in an ephemeral wetland in South Island, New Zealand, to inform management of this biodiverse but globally imperilled habitat. Our approach details among the first applications in ecology of Bayesian structural equation modelling, demonstrating its potential to inform management by disentangling the relative importance of strongly intercorrelated processes. 3. We found that invasion by non-native plants was lowest in sites where the physical disturbance caused by flooding was both intense and frequent. This effect was stronger than the positive response of non-native species to high soil N supply, which was positively related to flooding. 4. Sites flooded over a 4-year period had greater reductions in invasion than those associated with floods in the year prior to plot measurement because non-native species lacked traits for long-term persistence beneath water. Grazer exclusion had a small positive effect on invasion, as non-native species were preferentially selected by the herbivores at our site. 5. Our results show that only species adapted to the dominant disturbance regimes at a site may become successful invaders. Species native to ephemeral wetlands have specially evolved traits that allow them to persist and dominate in these sites. 6. Synthesis and applications. Predictions of invasions in a world of multiple disturbances clearly need to consider whether the evolutionary history of non-native species predisposes them to invade novel communities. Maintaining hydrological and nutrient regimes of ephemeral wetlands will limit the number of introduced species that are pre-adapted to become invasive.

House mice are among the most widely distributed mammals in the world, and adversely affect a wide range of indigenous biota. Suppressing mouse populations, however, is difficult and expensive. Cost-effective suppression requires knowing how low to reduce mouse numbers to achieve biodiversity outcomes, but these targets are usually unknown or not based on evidence. We derived density-impact functions (DIFs) for mice and small indigenous fauna in a tussock grass/shrubland ecosystem. We related two indices of mouse abundance to five indices of indigenous lizard and invertebrate abundance measured inside and outside mammal-resistant fences. Eight of 22 DIFs were significantly non-linear, with positive responses of skinks (Oligosoma maccanni, O. polychroma) and ground wētā (Hemiandrus spp.) only where mice were not detected or scarce (< 5% footprint tunnel tracking rate or printing rate based on footprint density). Kōrero geckos (Woodworthia spp.) were rarely detected where mice were present. A further 9 DIFs were not differentiated from null models, but patterns were consistent with impacts at 5% mouse abundance. This study suggests that unless mouse control programmes commit to very low abundances, they risk little return for effort. Impact studies of invasive house mice are largely restricted to island ecosystems. Studies need to be extended to other ecosystems and species to confirm the universality or otherwise of these highly non-linear DIFs.

The area of indigenous vegetation and habitat remaining on New Zealand's primary agricultural lands continues to decrease, but it has been difficult to obtain reliable estimates of the extent and causes of loss. We assess change and identify predictors of vegetation clearance in 856 recommended areas for protection (RAPs) from 35 ecological districts in the North and South Islands, New Zealand, for the period 1989 to 2015. Over 27 years, 7152 ha of these RAPs were cleared (2.3% by area), with rates varying over space and time. Native forest was least commonly cleared (422 ha removed), followed by native non-woody vegetation (1294 ha), native shrubland (1378 ha), and 'other' vegetation (4058 ha). The probability of clearance peaked during 2001 to 2008 at 0.14% yr-1 , but it was still nearly double the 1989-2001 levels (0.06% yr-1) from 2008 to 2015 (0.11% yr-1). The annualised clearance probabilities after 2001 were comparable to the rates of deforestation in the pre-1840 period of human settlement and about a third of that recorded from 1840 to 1970, the most intensive known period of anthropogenic clearance in New Zealand. Clearance rates were higher around the edges of small RAPs without legal protection and in drier, cooler areas, generally and increasingly over time. Amount of surrounding cropping/horticulture was negatively associated with clearance, as initially was dairy before developing a slightly positive association. Forestry was positively associated with clearance up until 2008. Our results show proportionally greater clearance of marginal agricultural land with high biodiversity values as time goes on, probably facilitated by the increasing use of technology, such as irrigation and fertilisation, to circumvent environmental limitations to plant growth. These results demonstrate ongoing attrition of the highest-value native habitat remaining on private land, and the inadequacy of the current protection framework to safeguard it.

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Evolutionary priority effects, where early-arriving lineages occupy niche space via diversification and preclude dominance of later arrivals, have been observed in alpine and forest communities. However, the potential for evolutionary priority effects to persist in an era of rapid global change remains unclear. Here, we use a natural experiment of historical disturbance in New Zealand to test whether anthropogenic changes in available habitat and nonnative invasion eliminate the role of evolutionary priority effects in community assembly. We also test whether evolutionary priority effects diminish with decreasing resource availability. Older plant clades, as estimated by clade crown age, were relatively more abundant in both primary and secondary grassland. Relative abundance in primary grassland decreased with clade stem age, but only weakly. However, for both clade age estimates, relative abundance decreased with age when nonnative biomass was high and soil moisture was low. Our data show that patterns in community structure consistent with evolutionary priority effects can occur in both primary and secondary grasslands, the latter created by anthropogenic disturbance. However, nonnative invasion may overwhelm the effect of immigration timing on community dominance, possibly as a result of high immigration rates and preadaptation to anthropogenically modified environments.