https://hdl.handle.net/10182/5 Sun, 21 Jan 2018 10:52:37 GMT 2018-01-21T10:52:37Z https://hdl.handle.net/10182/8903 Intraspecific variation in indirect plant-soil feedbacks as a driver of a wetland plant invasion Allen, Warwick; Meyerson, L. A.; Flick, A. J.; Cronin, J. T. Plant-soil feedbacks (PSFs) can influence plant competition via direct interactions with pathogens and mutualists or indirectly via apparent competition/mutualisms (i.e., spillover to co-occurring plants) and soil legacy effects. Presently, it is unknown how intraspecific variation in PSFs interacts with the environment (e.g., nutrient availability) to influence competition between native and invasive plants. We conducted a fully crossed multi-factor greenhouse experiment to determine the effects of soil biota, interspecific competition, and nutrient availability on biomass of replicate populations from one native and two invasive lineages of common reed (Phragmites australis) and a single lineage of native smooth cordgrass (Spartina alterniflora). Harmful soil biota consistently dominated PSFs involving all three P. australis lineages, reducing biomass by 10%, regardless of nutrient availability or S. alterniflora presence as a competitor. Spillover of soil biota derived from the rhizosphere of the two invasive P. australis lineages reduced S. alterniflora biomass by 7%, whereas soil biota from the native P. australis lineage increased S. alterniflora biomass by 6%. Interestingly, regardless of lineage, P. australis soil biota negatively affected S. alterniflora biomass when grown alone (i.e., a soil legacy), but had a positive impact when grown with P. australis, suggesting that P. australis is preferred by harmful generalist soil biota or facilitates S. alterniflora via spillover (i.e., apparent mutualism). Soil biota also reduced the negative impacts of interspecific competition on S. alterniflora by 13%, although it remained competitively inferior to P. australis across all treatments. Moreover, competitive interactions and the response to nutrients did not differ among P. australis lineages, indicating that interspecific competition and nutrient deposition may not be key drivers of P. australis invasion in North America. Taken together, although soil biota, interspecific competition, and nutrient availability appear to have no direct impact on the success of invasive P. australis lineages in North America, indirect spillover and soil legacies from P. australis occur and may have important implications for co-occurring native species and restoration of invaded habitats. Our study integrates multiple factors linked to plant invasions, highlighting that indirect interactions are likely commonplace in driving successful invasions and their impacts on the local community. Fri, 07 Jul 2017 00:00:00 GMT https://hdl.handle.net/10182/8903 2017-07-07T00:00:00Z https://hdl.handle.net/10182/8899 Valuing conservation benefits of disease control in wildlife: a choice experiment approach to bovine tuberculosis management in New Zealand's native forests Tait, Peter R.; Saunders, Caroline M.; Nugent, Graham; Rutherford, Paul We assess the non-monetary environmental benefits that accrue incidentally in New Zealand (NZ) from pest management conducted primarily to control an animal disease, bovine tuberculosis (TB). TB is an infectious disease that is one of the world's most serious animal health problems and, in many parts of the developing world, still a major mortality risk for humans. The incidence of TB in New Zealand (NZ) farmed livestock has been reduced progressively over the last 20 years, largely due to extensive and sustained population control of the main wildlife reservoir of disease, the introduced brushtail possum. Possums are also major pests that threaten indigenous forest biodiversity, and so extensive possum control for TB mitigation also incidental benefits conservation, but the extent and public value of this benefit has yet to be quantified. We conducted a choice experiment survey of the NZ public in an effort to value the native forest biodiversity benefits of TB-related possum control. We find strong public support for conservation outcomes consequent to TB-possum control in public native forests. The public place substantial value on the most observable biodiversity benefits of TB possum control, such as improved forest canopies and presence of native birds. The benefits, costs and values of TB-possum control are discussed in relation to the future directives of NZ's TB control programme, which is headed toward first regional and then national level disease eradication. Wed, 15 Mar 2017 00:00:00 GMT https://hdl.handle.net/10182/8899 2017-03-15T00:00:00Z https://hdl.handle.net/10182/8894 Lineage overwhelms environmental conditions in determining rhizosphere bacterial community structure in a cosmopolitan invasive plant Bowen, J. L.; Kearns, P. J.; Byrnes, J. E. K.; Wigginton, S.; Allen, Warwick; Greenwood, M.; Tran, K.; Yu, J.; Cronin, J. T.; Meyerson, L. A. Plant–microbe interactions play crucial roles in species invasions but are rarely investigated at the intraspecific level. Here, we study these interactions in three lineages of a globally distributed plant, Phragmites australis. We use field surveys and a common garden experiment to analyze bacterial communities in the rhizosphere of P. australis stands from native, introduced, and Gulf lineages to determine lineage-specific controls on rhizosphere bacteria. We show that within-lineage bacterial communities are similar, but are distinct among lineages, which is consistent with our results in a complementary common garden experiment. Introduced P. australis rhizosphere bacterial communities have lower abundances of pathways involved in antimicrobial biosynthesis and degradation, suggesting a lower exposure to enemy attack than native and Gulf lineages. However, lineage and not rhizosphere bacterial communities dictate individual plant growth in the common garden experiment. We conclude that lineage is crucial for determination of both rhizosphere bacterial communities and plant fitness. Tue, 05 Sep 2017 00:00:00 GMT https://hdl.handle.net/10182/8894 2017-09-05T00:00:00Z https://hdl.handle.net/10182/8883 Greater focus needed on alien plant impacts in protected areas Hulme, Philip E.; Pyšek, P.; Pergl, J.; Jarošík, V.; Schaffner, U.; Vilà, M. Alien plants pose significant threats to protected areas worldwide yet many studies only describe the degree to which these areas have become invaded. Research must move toward a better understanding of alien plant impacts since managers urgently require an appropriate evidence base to prioritize control/eradication targets. We analyze a global database of quantitative studies of alien plant impacts to evaluate existing knowledge of alien plant impacts within and outside protected areas. Although protected areas are a significant focus for quantitative impact studies, the biogeographic emphasis of most research effort does not coincide with the global distribution of protected areas nor the plant species or life-forms recognized to have greatest impacts on ecosystems. While impacts were often as significant within protected areas as outside, only a minority of studies provide any subsequent management recommendations. There is therefore considerable scope to improve the evidence base on alien plant management in protected areas. Mon, 01 Sep 2014 00:00:00 GMT https://hdl.handle.net/10182/8883 2014-09-01T00:00:00Z