Warwick Harris

Essential oils from New Zealand manuka and kanuka: Chemotaxonomy of Leptospermum

Standardized steam distillation and GC analytical methods for oils from manuka, Leptospermum scoparium, are described. These methods were used to analyse two oils from each of 15 L. scoparium populations derived from all around New Zealand, seven Australian Leptospermum populations and one population of Kunzea sinclairii. These populations were all grown from seed at a single site. Principal component analyses of the levels of 50 GC peaks in these 46 oils revealed compositional patterns. Kunzea sinclairii oils were distinguished from Leptospermum oils by higher α-pinene levels (mean 76%). Australian Leptospermum oils had significantly higher 1,8-cineole (mean 20%) and total monoterpene levels (mean 51%) than New Zealand L. scoparium oils (1,8-cineole mean 0.9%, total monoterpene mean 14%). This indicates the need for further taxonomic study of plants currently included in L. scoparium in Australia and New Zealand. There is evidence for three chemotypes of L. scoparium in New Zealand, conforming in part to morphological types: a high-pinene chemotype in the far north, a high-triketone (especially leptospermone) chemotype on the East Cape, and a type containing a complex of sesquiterpenes found over the rest of the country. An oil from the East Cape chemotype showed the strongest antimicrobial activity.

Effects of soil fertility level and cutting frequency on interference among Hieracium pilosella, H. praealtum, Rumex acetosella, and Festuca novae‐zelandiae

Abstract The role of ecological factors in the invasion of fescue tussock grassland by Hieracium species was investigated in a box experiment. Soil fertility and cutting frequency effects on interference between the introduced flat weeds Hieracium pilosella, H. praealtum, and Rumex acetosella and the native bunch grass Festuca novae‐zelandiae established on a denuded soil were examined using a model and technique involving stress and disturbance gradients. The weed species showed marked biomass and phenological responses to increased availability of mineral nutrients compared to F. novae‐zelandiae, which had reduced yield at the highest level of soil fertility. At high soil fertility, R. acetosella suppressed both Hieracium species and F. novae‐zelandiae, probably because it competed more effectively for light. Cutting frequency also influenced the pattern of interference between the species by effects on competition for light, vegetative spread, and partitioning of biomass to parts of the plants above an...

Comparison of gross primary productivity derived from GIMMS NDVI3g, GIMMS, and MODIS in Southeast Asia

Gross primary production (GPP) plays an important role in the net ecosystem exchange of CO2 between the atmosphere and terrestrial ecosystems. It is particularly important to monitor GPP in Southeast Asia because of increasing rates of tropical forest

Effects of plateau pika (Ochotona curzoniae) on net ecosystem carbon exchange of grassland in the Three Rivers Headwaters region, Qinghai-Tibet, China

Background and aimBecause the indigenous burrowing lagomorph plateau pika (Ochotona curzoniae) is considered to have negative ecological impacts on alpine meadow steppe grasslands of the Headwaters Region of the Yellow, Yangtze and Mekong Rivers we investigated its effects on ecosystem productivity and soil properties, and especially net ecosystem carbon flux.MethodsWe measured net ecosystem CO2 exchange (NEE) and its components gross ecosystem productivity (GEP) and ecosystem respiration (ER) at peak aboveground biomass by the chamber method with reference to plant and soil characteristics of areas of alpine meadow steppe with different densities of pika burrows.ResultsHigher burrow density decreased NEE, GEP and ER. Above-ground biomass, species number, plant cover and leaf area index decreased with increasing pika density. Higher burrow density was associated with lower soil moisture and higher soil temperature. Responses of NEE were related to changes of abiotic and biotic factors affecting its two components. NEE was positively related to soil moisture, soil ammonium nitrogen, plant cover, leaf area index and above-ground biomass but was negatively correlated with higher soil nitrate nitrogen.ConclusionDecrease of NEE by plateau pika may reduce the carbon sink balance of Qinghai-Tibet plateau grassland. Such effects may be influenced by grazing pressure from domestic livestock, population levels of natural predators, and climate change.

Curling and folding of leaves of monocotyledons — a strategy for structural stiffness

Abstract Leaves of most monocotyledonous plants gain structural stiffness from curling or folding. This is shown to be true of Phormium spp., where the optimisation seems to be for the leaf to gain as much stiffness as possible by curling longitudinally whilst keeping the maximum amount of projected area available for intercepting light. Smaller plants with less leaf fibre have to fold about the midrib to gain this stiffness, which will reduce their projected area more than curling would but reduces the investment in fibre content.

Extraction, content, strength, and extension of Phormium variety fibres prepared for traditional Maori weaving.

Abstract The traditional haro method was used to strip fibres from the leaf blades of 11 Phormium varieties used by Maori for traditional weaving and plaiting. The content, strength, and extension characteristics of fibres differed markedly among the varieties. These fibre characteristics also differed according to the part of the leaf blade from which the fibre was extracted. Although strong correlations showed that varieties with high fibre content also had the strongest and most extendable fibre, some varieties deviated from those relationships. The fibre characteristics of the varieties correspond to their traditional uses by Maori and also to their history of use in the now defunct commercial phormium‐fibre industry.

Ethnobotanical study of growth of Phormium varieties used for traditional Maori weaving

Abstract Twelve Maori weaving varieties of Phormium were grown at 11 widely separated sites in New Zealand in an experiment involving participation of weavers, teachers, and students. Leaf dieback and leaf appearance during establishment and growth of leaf length and blade width, shoot production, and expansion of plant basal circumference over 4–7 years were recorded. Observations were made on factors, particularly cold, that caused plant damage. Data were analysed to test for site × variety interaction. The sites provided environments ranging from those at Ohakune and Kaiapoi which were lethal for some varieties to that at Auckland which was near optimal for growth. Generally, growth reduction during the cool period of each year was proportionally greater at sites that overall had the best conditions for growth. Variety growth responses and their susceptibility to cold damage differed and interacted significantly with site conditions. The results are related to varieties in the National New Zealand Flax Collection in respect to their origins and history of use. Recommendations are made for cultivation practices that enhance the production of leaves used for traditional Maori weaving.

Variation of inherent seed capsule splitting in populations of Leptospermum scoparium (Myrtaceae) in New Zealand

Abstract Variation in the splitting of seed capsules was observed for 61 populations of Leptospermum scoparium from a wide latitudinal range in New Zealand raised from two sowings and grown in uniform environments. Variation ranged from populations for which capsules of all shrubs had split and shed seed within a year of their formation to those for which all shrubs had serotinous capsules that remained intact and retained seed for a longer period. There was a significant latitudinal gradient in this variation with northern populations being strongly serotinous. The variation of capsule splitting was independent of the time taken from sowing to the first flowering of plants. These results are discussed with regard to the ecological adaptation of L. scoparium to various habitat disturbance factors. It is concluded that the variation observed is consistent with the opinion that the New Zealand flora generally lacks fire adaptation but, since human settlement, rapid selection of fire‐adapted genotypes of L. scoparium has occurred in populations that are seral in secondary succession to forest.

Essential oils from new zealand manuka and kanuka: Chemotaxonomy of Kunzea

Abstract A standardized analytical GC method has been used to analyse essential oils from selected Australian and New Zealand Kunzea species, grown from seed at a single site. The distillation yields and analyses are reported for oils from 26 populations of K. ericoides (kanuka) and from single populations of each of K. flavescens , K. pauciflora , K. sinclairii and x Kunzspermum hirakimata (a Kunzea x Leptospermum cross). Principal components analyses of 37 GC peaks in these oils were used to distinguish compositional patterns. Oils from K. flavescens , K. pauciflora and x Kunzspermum hirakimata had chemical compositions distinct from K. sinclairii and K. ericoides . Oils front New Zealand K. ericoides were mainly α-pinene (mean 68%), but some oils had high p -cymene contents, particularly oils from one Marlborough provenance (mean 31%). A wild population of K. ericoides var. linearis gave oils with similar composition to other K. ericoides . Two K. ericoides oils showed weak antifungal activity.

Variation in response to cold damage by populations of Cordyline australis and of some other species of Cordyline (Lomandraceae)

Abstract Winter cold damage in 1996 and 1997 was recorded for 28 populations of Cordyline australis from a wide latitudinal range in New zealand and single populations of C. banskii and C, indivisa grown in field experiments at Lincoln and Invermay New Zealand. Damage to a single plant of C. obtecta grown at Lincoln was also recorded. Cordyline banskii and C. obtecta were damaged the most by freezing. Levels of cold damage to C. australis were closely related to latitude of origin; populations from northern North Island suffered severe damage whereas those from inland southern south Island showed little damage. These relationships were clearest when the populations were exposed to the lowest grass minimum temperature of ‐9.7°C that occurred at Invermay in winter 1996. Retardation of the height growth of the populations most severely damaged in winter 1996 kept them in the frost layer in winter 1997, increasing their exposure to further damage. Variation in cold damage that related to altitude and topography of the sites of origin was also indicated. Damage to shoot apices by freezing temperatures at Invermay in 1996 induced plants of northern populations to form multiple shoots. The results suggest that there has been strong natural selection matching the cold tolerance of seedlings of C. australis populations to minimum temperature regimes at their sites of origin. The results are relevant to the sourcing of plants for restoration of native vegetation and to horticultural use of C. australis.