Time filter

Source Type

Dunedin, New Zealand

Smissen R.D.,Landcare Research | De Lange P.J.,Ecosystems and Species Unit | Thorsen M.J.,Otago Conservancy
New Zealand Journal of Botany | Year: 2011

As traditionally circumscribed, Simplicia buchananii is an endemic of north-west Nelson, New Zealand, with all known records coming from the Kahurangi National Park. Simplicia laxa is more widespread with historical records from the eastern Wairarapa, and Otago. Neither grass is common and both are listed as Threatened. In 2005, Simplicia was discovered near Taihape in the central North Island. These plants had morphological attributes of both S. buchananii and S. laxa. We explored genetic variation in Simplicia using amplified fragment length polymorphism DNA fingerprinting and DNA sequencing of the plastid trnL intron and trnL-F intergenic spacer and the nuclear ribosomal internal transcribed spacer and external transcribed spacer regions. Populations in the Taihape area are referable to S. laxa. However, they and plants from a site in North Otago are genetically distinct from other South Island S. laxa plants and their taxonomic status needs further exploration. © 2011 The Royal Society of New Zealand.

Gous S.,Scion Research | Raal P.,Otago Conservancy | Watt M.S.,Scion Research
New Zealand Journal of Forestry Science | Year: 2014

Background: Wilding conifers are a major threat to biological conservation within New Zealand and currently cover at least 500,000 ha throughout the South Island. A range of herbicide treatments was applied to field trials established within wilding Pinus contorta (height range 1 – 15 m) and P. mugo (height range 0.5 – 5 m) infestations. Measurements of mortality taken two years post herbicide application were used to determine the efficacy of (i) the traditionally used contact herbicide diquat, applied in an application volume of 300 L ha-1, and (ii) a range of systemic herbicides applied in an application volume of 150 L ha-1. Methods: All herbicides were applied by helicopter using a coarse droplet spectra (VMD = 720 μm) to minimise spray drift. Damage assessments were made two years following application and trees were considered to have died if they had 100% dead foliage. The influence of height class and treatment on tree mortality was assessed using analysis of variance. Results: For a treatment to be considered effective, a mortality rate of over 85% should be achieved on all trees up to 8 m in height. Under this criterion, none of the treatments used in this study provided satisfactory control of the two wilding species. Application of 7200 g ha-1 glyphosate and 120 g ha-1 metsulfuron was significantly better than any other treatment, for both species, causing 64% mortality for P. contorta and 36% for P. mugo. The traditionally used herbicide diquat was the poorest performing herbicide for P. contorta and the second poorest performing for P. mugo, inducing respective mortality rates of 2.7% and 2.4%. For all herbicides used there was a significant decline in efficacy with increases in tree height. Conclusion: These results suggest that control of dense wilding pine stands using low spray volumes and coarse droplet size is unlikely to be successful as foliage coverage is poor. © 2014, Gous et al.; licensee Springer.

Sancho G.,National University of La Plata | de Lange P.J.,Ecosystems and Species Unit | Donato M.,CONICET | Barkla J.,Otago Conservancy | Wagstaff S.J.,Landcare Research
Botanical Journal of the Linnean Society | Year: 2015

Lagenophora (Astereae, Asteraceae) has 14 species in New Zealand, Australia, Asia, southern South America, Gough Island and Tristan da Cunha. Phylogenetic relationships in Lagenophora were inferred using nuclear and plastid DNA regions. Reconstruction of spatio-temporal evolution was estimated using parsimony, Bayesian inference and likelihood methods, a Bayesian relaxed molecular clock and ancestral area and habitat reconstructions. Our results support a narrow taxonomic concept of Lagenophora including only a core group of species with one clade diversifying in New Zealand and another in South America. The split between the New Zealand and South American Lagenophora dates from 11.2Mya [6.1-17.4 95% highest posterior density (HPD)]. The inferred ancestral habitats were openings in beech forest and subalpine tussockland. The biogeographical analyses infer a complex ancestral area for Lagenophora involving New Zealand and southern South America. Thus, the estimated divergence times and biogeographical reconstructions provide circumstantial evidence that Antarctica may have served as a corridor for migration until the expansion of the continental ice during the late Cenozoic. The extant distribution of Lagenophora reflects a complex history that could also have involved direct long-distance dispersal across southern oceans. © 2014 The Linnean Society of London.

Gous S.,Scion Research | Raal P.,Otago Conservancy | Watt M.S.,Scion Research
Clinical and Translational Imaging | Year: 2014

Background: Invasive wilding conifer species are a major threat to biological conservation in New Zealand. Scattered individual plants are particularly problematic as these are very costly to treat and once they reach reproductive maturity can act as point sources for further invasion. A novel method is described in this paper that delivers a precise dose of oil-based herbicide mixtures into the tree crown via a hand held lance using a helicopter as a platform. Using this method the objective of this research was to test the efficacy of six triclopyr based herbicides in an oil carrier, on isolated naturally occurring Pinus contorta (Dougl.) and P. nigra subsp. laricio (Poir.) Maire.Methods: For each species and treatment combination treated trees covered a wide range of heights, ranging from ca. 0.5 to 16 m. Measurements of mortality taken 24 months post herbicide application were used to examine variation in efficacy of these herbicides, where successful treatment was defined by a mortality rate of 85% or higher. Logistic regression models were fitted for each species and from these models we determined the threshold tree height at which 85% mortality occurred, H85.Results: For both species treatment efficacy significantly (P ≤ 0.05) declined as tree height increased. The two most effective treatments for both species were a 500 mL dose that included 60 g triclopyr in oil with addition of 1% alkylsilicone surfactant (20 G OM 500 mL) and a 1 litre dose that included 120 g triclopyr and 20 g picloram in oil (10G T20). Values of H85 for 10G 20T and 20 G OM 500 mL were, respectively, 7.7 m and 8.0 m for P. contorta and 7.1 m and 6.8 m for P. nigra.Conclusion: Spot application of triclopyr based herbicides, in an oil carrier, onto the tree crown was found to be an effective means of controlling two of the most vigorous New Zealand wilding conifer species. © 2014, Gous et al.; licensee Springer.

Gous S.,Scion Research | Raal P.,Otago Conservancy | Watt M.,Scion Research
New Zealand Journal of Forestry | Year: 2012

There is not much information on aerial application of herbicides to control wilding conifers in New Zealand. Two South Island study sites infested with dense Pinus contorta were selected to conduct trials testing the efficacy of aerial application of various herbicide combinations. Four herbicide treatments were applied as a randomised complete block of three replications at each site. Herbicides were applied by helicopter during January 2011 using a boom spraying system calibrated to deliver 400 1/ha. Spray efficacy was determined by measurements of percentage of dead foliage (damage) and mortality 12 months post treatment. Of the four herbicides tested the most effective included 18,000 g triclopyr, 5,000 g dicamba, 2,000 g picloram and 2,300 g ammonium sulphate in an application volume of 400 1/ha. For this treatment tree mortality and damage were respectively 86.6% and 98.6%. Because the systemic herbicides tested here are only effective during the active growing season it is anticipated that mortality may increase in the future.

Discover hidden collaborations