10.5061/DRYAD.0CFXPNVZQ
Peterson, Paul
Manaaki Whenua - Landcare Research
Merrett, Merilyn
The Open Polytechnic Of New Zealand
Fowler, Simon
Manaaki Whenua - Landcare Research
Barrett, Paul
Massey University
Paynter, Quentin
Manaaki Whenua - Landcare Research
Data from: Comparing biocontrol and herbicide for managing an invasive
non-native plant species: efficacy, non-target effects and secondary
invasion
Dryad
dataset
2020
heather beetle
Lochmaea suturalis
selective herbicide
invasive weed suppression
native species recovery
non-target damage
insecticide-exclusion
Ministry of Business, Innovation and Employment
https://ror.org/02jtq1b51
Core funding
2020-07-01T00:00:00Z
2020-07-01T00:00:00Z
en
139094 bytes
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CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
1. Globally, invasive non-native plants are an increasing threat to
indigenous biodiversity and ecosystems, but management can be compromised
by poor efficacy of control methods, harmful non-target effects or
secondary invasions by other non-native plant species. 2. A 5-year field
trial compared two stakeholder-selected control methods for heather, a
European plant invading native ecosystems in and adjoining Tongariro
National Park in New Zealand. The control methods were a selective
herbicide (Pasture Kleen®; 2,4-D ester) and biocontrol with an introduced
beetle Lochmaea suturalis (Coleoptera: Chrysomelidae). 3. Biocontrol
reduced mean heather cover by 97%, slightly more than herbicide at 87%,
compared with a 20% increase in heather under no management. 4. Cover of
native dicots, the most species-rich plant group, increased following
biocontrol. In contrast, herbicide application had major non-target
effects on native dicots, reducing their percentage cover and species
richness. Native monocot cover and species richness increased following
both herbicide and biocontrol treatments. 5. A similar 8-fold increase in
non-native monocots occurred following both biocontrol and herbicide
treatments. Overall, secondary invasion was greatest with biocontrol
because non-native dicot cover also increased, whereas herbicide almost
eliminated non-native dicots. 6. Synthesis and applications. Biocontrol
and herbicide treatments both controlled heather but herbicide application
was associated with severe non-target impacts on native dicots. Benefits
to the native flora were consequently greatest in the biocontrol
treatment, despite greater secondary invasion. Control strategies for
management of widespread non-native plants to optimize ecosystem outcomes
should include more consideration of biocontrol.
This dataset if from 5-year field trial compared two stakeholder-selected
control methods for heather Calluna vugarus, a European plant invading
native ecosystems in and adjoining Tongariro National Park in New Zealand.
The control methods were a selective herbicide (Pasture Kleen®; 2,4-D
ester) and biocontrol with an introduced beetle Lochmaea suturalis
(Coleoptera: Chrysomelidae). Data include percentage cover of heather and
competing plant species and species richness within the study plots
Twenty-four 5 × 5 m plots (six blocks of four plots) were located around
the periphery of a developing heather beetle outbreak at 39° 21’ 57.3” S,
175° 42’ 55.1” E during November 2007. In each block one plot was randomly
assigned to one of four treatments; 1. Control (insecticide spray to
protect vegetation from beetle feeding), 2. Biocontrol (to expose heather
to beetle feeding only), 3. Herbicide (herbicide + insecticide to protect
vegetation from beetle feeding but expose it to herbicide), and 4.
Biocontrol + herbicide (to expose vegetation to beetle feeding and
herbicide). The herbicide used was Pasture Kleen® @ 6.5ml/L applied in
December 2007 and 2008 to match the method being employed by the NZ
Defence Force (NZDF) within the WMTA. The insecticide used was a synthetic
pyrethroid Karate Zeon @ 1ml/15L + 0.3ml/L Vapor Guard, which was found to
successfully eliminate beetles from treated plots. A concurrent
insecticide check experiment at a locality where heather beetle was absent
indicated that insecticide did not directly affect plant cover or species
richness (Appendix 1 SI). Insecticide applications were made in 2007
(November), 2008 (January, February, March, September, October (twice),
December), 2009 (January, February, September), 2010 (October), and 2011
(October). The frequency was reduced over time because, after the feeding
front of heather beetles had moved well past the plots, there was less
re-invasion of the plots by beetles. Herbicide and insecticide were
applied separately, mostly on different dates, to a 7 × 7 m area to avoid
edge effects, with a minimum buffer of 3 m to the edge of the next 7 × 7 m
treatment area. On the one occasion when herbicide and insecticide were
applied on the same date, the first application was allowed to dry before
the second application. Both herbicide and insecticide were applied to
run-off. Plots not treated with herbicide or insecticide were sprayed with
water to run-off on the same dates the chemicals were applied. The
insecticide treatment was found to be highly effective at reducing
defoliation of heather (Appendix 2 SI). Absolute percentage of cover all
vascular and non-vascular (bryophytes, clubmosses and lichens) plant
species was assessed visually in four 50 × 50 cm subplots, one in each
plot corner, between the 1st and 12th February in each of 2008, 2009,
2010, and 2012.
We conducted repeated measures ANOVAs on the data. Percentage cover
("Raw cover data" worksheet) was converted to proportions and
analysed for heather, clubmosses, lichens, and bryophytes, and cover and
species richness were analysed for summed groups of native dicots, native
monocots, non-native dicots (excluding heather) and non-native monocots.
To avoid pseudoreplication, the average cover across the four quadrats
(se, ne, nw, sw) per plot in the "Raw cover data" was analysed
and the total number of plant species in all four quadrats was summed in
the species richness analysis.