This thesis demonstrates some of the potential of Phyllocladus trichomanoides D. Don (tanekaha) for dendrochronological research, especially dendroclimatology. The type of vegetation associated with sites producing a chronology showed no obvious pattern. The resulting non-specific range of suitable sites for dendrochronological sampling was thought to be a favorable species characteristic. Standardization of tree-ring series using a 50-year Gaussian filter resulted in 28% improvement of retained common variance above that obtained from using conventional polynomial filters. The problem of autocorrelation was investigated. Tanekaha had a consistent autocorrelation pattern through both space (i.e. latitudinal and altitudinal ranges) and time (preserved forest and contemporary stands). P. glaucus (toatoa) also showed a spatially consistent yet distinctive pattern. These different diagnostic patterns implied a non-climatic cause (i.e. physiological), illustrating the need to ensure their removal before species chronologies are compared or used for climate modelling. Low order autoregressive models (ARMA(p,0)) were used to filter out the significant levels of autocorrelation. Subsequent comparison of the chronologies showed a consistent and highly significantly correlated pattern between both sites and species. The paucity of information about the physiology of Phyllocladus spp. led to the testing of several climatic variables in response function analyses. The "best" variables (based on only statistical evidence) were minimum monthly temperature, monthly total raindays and an optimal 12 month span of August (t) to July (t+1). Preliminary attempts with response functions using different combinations of predictor (climate variables) and predictand (chronologies) data sets generally failed to verify. Neither the extent of time from which the response functions were based (no analogue situation) nor a supposed "physiological shock" period (poor growth period) were the causes for non-verification. Further investigation showed that, for both the individual and combined chronologies, the temperature response was similar but rainfall varied. The instability through time of the rainfall response was particularly disconcerting since it broke one of the fundamental assumptions used in dendroclimatology. It was therefore concluded that climatic reconstruction could be attempted only on the temperature data. The temperature data of three seasons (spring, summer and autumn) were tried with transfer function models. Of these the summer season explained the most variance and had the highest reduction of error(RE) values. The selected model used the period 1918 to 1982 for calibration and 1853 to 1917 for verification. Summer temperatures from 1982 to 1750 were reconstructed. The reconstruction modeled only c.30% of the variance but was highly correlated to the summer temperature series developed by Norton (1983). This was interpreted as further independent verification of the reconstructed series. The summer temperatures reconstructed from 1982 to 1750 were concluded to have been similar to the recorded pattern from 1853. The same regressors were applied to the buried forest chronology and the summer temperatures reconstructed from 105 BC to AD 175. Because of the non-continuous tree-ring record no comment can be made of actual ambient conditions in comparison to those of today. However, the reconstructed pre-Taupo summer series did show increased variation towards the time of the eruption and more pronounced cool summers than hot ones. Another applied use of a tanekaha chronology was demonstrated with 14C dating. A statistically significant fit of 14C ages was obtained between twelve contiguous decades from the buried forest tanekaha chronology with that from a Northern hemisphere decadal calibration curve based on Sequioadendron giganteum(Stuiver & Becker 1986). This "wiggle-matching" to the calibration curve places the year of the Taupo eruption as AD 177±18 10. An Independent check of the "new" date was conducted using the most reliable data of Healy et al. (1964) with the same calibration series as described above. A date of AD177±4 44 was obtained which supports the wiggle-matched date. The confidence interval of the wiggle-matched date also coincides with the date proposed by Wilson et al. (1980) of AD186 (based purely on ancient written records).

A total of six hundred and sixteen fungal and two hundred and thirty two bacterial isolates were obtained either from the sapwood of Pinus radiata or from other sources, including UV mutagenesis. All isolates were screened on Pinus radiata wood chips for their survival and colonisation attributes. Of these isolates, two hundred and eighty two failed to grow or caused permanent deep seated discolourations or decay and were eliminated from the study. The remaining five hundred and sixty six isolates were assessed for their antagonistic ability against sapstain. In a dual screen on Pinus radiata wood chips, one hundred and twelve fungal and four bacterial isolates inhibited the growth of the known sapstain fungus, Ophiostoma piceae. In a second biological control screen, on Pinus radiata wood blocks, isolates of Gliocladium viride, Gliocladium roseum, Trichoderma hamatum, Trichoderma harzianum, Trichoderma sp., Trichothecium roseum and an isolate of the Thelephoraceae proved inhibitory to the sapstain isolates Ophiostoma piceae and Sphaeropsis sapinea providing between 94 and 100% control. These isolates were considered for further examination in the field. The remaining isolates provided poor or inconsistent inhibition or were mould fungi and, therefore, not suitable for direct application. All fungal and bacterial isolates that had shown inhibitory ability in the initial biological control screen and the remaining non-staining bacteria were examined for their ability to produce non-volatile metabolites that were inhibitory to sapstain. The bacterial isolates were examined in a preliminary dual plate screen in which 91 isolates were identified as producing inhibitory compounds. The best of these bacterial isolates were screened, with the fungal isolates, in a non-volatile metabolite trial utilising filter sterilised culture filtrates. Isolates of Bacillus sp., Fusarium solani, Gliocladium roseum, Gliocladium virens, Trichoderma harzianum, Trichoderma sp., Trichoderma viride and Trichothecium roseum were found to be significantly inhibitory to the growth of Ophiostoma piceae at concentrations of 50% or less. However, the filtrates did not provide adequate sapstain control, when tested on Pinus radiata wood block, to prompt consideration for further examination in the field. Studies are currently examining several of these isolates for the production of biologically active compounds. The six most promising isolates, from the wood chip and wood block trials, were tested in the field for their ability to control sapstain on unseasoned Pinus radiata sapwood and/or peeled logs. These were Gliocladium viride (FK75), Trichoderma hamantum (FK561), Trichoderma harzianum (FK228), Trichoderma sp. (FK247), Trichothecium roseum (FK238) and an isolate of the Thelephoraceae (FK33). The fungi were prepared as mycelial/spore homogenates. For application to the timber, the homogenates were mixed with 0.2% Alcosorb gel, producing 108 cfu/ml suspensions, these suspensions were applied by dipping. Diluted homogenates, 108 cfu/ml, were applied as spray treatments to the logs. All of the biological control agent treatments reduced the level of sapstain on either the logs or timber with Trichoderma harzianum (FK228), Trichoderma sp. (FK247) and Trichothecium roseum (FK238) providing control equivalent to that of the fungicides NP-1 and Diffusol for portions of the trial. Trichoderma sp. (FK247) and Trichothecium roseum (FK238) gave sapstain control in excess of 90% for the first 30 days of the timber trial equalling the control provided by NP-1 and Diffusol. In another trial, Trichoderma harzianum (FK228) was more effective than NP-1, providing 60% sapstain control, after six months, on the internal tissue of Pinus radiata logs. The six isolates selected for the field trials were examined in additional studies. In a dual inoculation study, Trichoderma sp. (FK247) exhibited localised antibiotic ability causing the lysis of mycelium of sapstain fungi. There was no evidence of mycoparasitic action by any of the six isolates. Trichoderma harzianum (FK228), Trichoderma sp. (FK247) and Trichothecium roseum (FK238) were observed to degrade cellulose. However, neither these nor the other isolates caused a significant change in the mechanical properties of Pinus radiata timber when compared to untreated controls. Decreasing pH or the addition of nitrate were identified as having potential for the promotion of biological control agent growth. The potential of mixed biological control agent inoculations was also examined. While these results are preliminary, they are extremely encouraging and provide a basis from which future studies can develop.

Aquatic macrophytes possess an internal lacunar system of proliferated intercellular airspaces. Lacunar gas exchange processes were investigated in Egeria densa Planch., a submerged freshwater angiosperm. Investigations of oxygen exchange between Egeria shoot segments and the water revealed that up to 17% of the photosynthetically-produced oxygen is retained within the lacunae. A consequence of this partitioning, which results from the relatively low solubility of oxygen in water, is the development of internal lacunar pressures up to 20 kPa above atmospheric pressure. This storage of oxygen in Egeria casts doubts on oxygen-based measurements of productivity in aquatic macrophytes, unless both internal and external sinks are monitored. Pressurisation also revealed that storage is greater in static water than in flowing water, suggesting that boundary layer limitations to oxygen transfer can also affect partitioning. Pressures fall to sub-atmospheric values in the dark, due to respiratory consumption of the internal oxygen. The Egeria respiratory gas exchanges in the dark demonstrated a steady concentration gradient between plant and water within an hour of darkening. However, the material steadily consumes approximately 30% of its respired oxygen from the lacunae, rather than the water. This oxygen supply is again due to the low oxygen solubility. The lacunae also assist the radial oxygen supply into the respiring tissue; it was found that the Michaelis-Menten constant for the respiratory response to oxygen tension in Egeria was some two to three times greater in material with infiltrated lacunae than in uninfiltrated material. Oxygen storage in the stem lacunae resulted in a longitudinal (shoot to root) movement of this gas, which was monitored using a bicompartment apparatus. The root oxygen release rate varied with light intensity and water flow rate in a similar manner to the internal pressure changes. Further experiments, involving measurements of the oxygen flux rates in the Egeria rhizosphere, demonstrated that this root oxygen loss is capable of effecting substantial diurnal oxygen fluctuations in the surrounding sediment. These processes may be interrupted by natural infiltration of the airspaces, but the factors involved here remain uncertain. The mean internal oxygen transport rate in Egeria (6.28 μ102 h-1) was consistent with estimates of lacunar oxygen concentration gradients calculated from Fick's Law, suggesting that diffusion is the oxygen transport mechanism in Egeria. However, by connecting shoots into manometers, internal pressure gradients of some 0.9 kPa m-1 were detected. These gradients were 103 -fold greater than the pressure gradient required to account for oxygen transport in Egeria, but were transient features, as the pressure equilibrated throughout the lacunar system 20 - 30 minutes after a dark/light change. Mass flow was therefore proposed as a transitory, but potentially significant, contribution to oxygen transport. Root to shoot carbon dioxide transport was measured using 14CO2 tracing. The CO2 uptake (mean internal transport = 4.96 μ1CO2 h-1) represented <10% of the total carbon fixed; the concentration of root-derived carbon in shoot tissue declined rapidly from the root insertion point. These results are compared with those of previous studies, and the significance of the Egeria lacunar system assessed.

Two Coelomycete genera, Ascochytula Died. and Ascochytella Tassi, were studied in order to determine their generic affinities, especially with Ascochyta. Ascochytula obiones (Jaap) Died., the type species of Ascochytula, is considered to be congeneric with Ascochyta pisi Lib., the type species of the earlier genus, Ascochyta Lib. Ascochytula is thus reduced to synonymy with Ascochyta. Of the thirty-six species and two varieties named in, or directly associated with, Ascochytula, twenty are herein described as species of Ascochyta and four are excluded from Ascochyta. The remaining species were either not examined, or are nomina dubia. The following names are proposed: Ascochyta asparagina (Petrak) comb. nov., A. deformis (P. Karsten) comb. nov., A. dorycnii (Petrak) comb. nov., A. ludwigiana (Petrak) comb. nov., A. moravica (Petrak) comb. nov., A. obiones (Jaap) comb. nov., A. phlomidicola nom. nov., and A. ulicis (Grove) comb. nov. Ascochytella Tassi, which has often been confused with Ascochytula, is also synonymised with Ascochyta. The original thirteen species in Ascochytella were examined, and A. vicina (Sacc.) Tassi chosen as the lecto-type species. Most of the thirteen species are regarded as being either misplaced in Ascochytella, or nomina dubia, and only four, including the lectotype, are accepted as species of Ascochyta. The name, Placodiplodia canthiifolia (Cooke & Massee) comb. nov. is proposed. The type species of Ascochyta, and of six related genera, Ascochytulina Petrak, Coniothyrium Corda. Diplodina Westend., Pseudodiplodia (P. Karsten) Sacc., Scolecosporiella Petrak, and Stagonospora (Sacc.) Sacc. were studied to determine the distinctions between these six genera and Ascochyta. Microdiplodia Allescher and Diplodia Fr. are also discussed, in relationt to Ascochyta. Ascochyta paspali (H. Sydow) Punith. (≡ Ascochytula paspali H. Sydow), which causes a leaf stripe disease of Paspalum dilatatum Poir., an important perennial grass of northern North Island pastures, was examined in detail. At some temperatures, under controlled climate conditions, the fungus significantly reduced the yield of P. dilatatum. A. paspali was found to grow systemically, as mycelium within the xylem vessels, and was able to infect all parts of the plant, including the roots and seeds. Green leaves sometimes became infected systemically without production of visual symptoms. Infected seed is suggested as a means for disease spread. No teleomorph for A. paspali was found, and the fungus is thought to over-winter in the dormant grass. The seasonal fluctuation in levels of P. dilatatum and of the disease was studied in two Northland pastures with paspalum as a component. One pasture was studied for fourteen months, and the other for four months. Disease levels, and paspalum levels, were determined by point quadrat analysis and by sorting of randomly cut samples. Levels of both the host and of the disease peaked in summer, while both were at low levels, or apparently absent, over the winter months.

Several ecological aspects of the Manukau Harbour related to its benthic flora end fauna, water chemistry, sedimentology, and bacteriology were investigated. Vertical colour aerophotographs were taken of all vegetated tidelands within the Harbour and six vegetation types were indentified, mapped, and discussed in terms of their ecological significance. Meadows of the intertidal seaweed Gracilaria secundata var. pseudoflagellifera near the Manukau Sewage Oxidation Ponds were found to have increased virtually logarithmically in extent since the commencement of operations of the Manukau Purification Works. The possible relation of this increase to contributions of mutrients and fine sediments from the Ponds is considered. The effects of stress, sediment type, and the presence of macrovegetation on benthic faunal community structure are studied. The majority of the findings are somewhat inconclusive; however it is found that mangrove swamps and eelgrass flats clearly appear to increase faunal species diversity. Water and sediment nutrients were examined and found to be at high levels in the north-east region of the Harbour. It is concluded that sediments probably undergo less temporal variation in nutrient levels than do overlying waters and might therefore provide a more cost-effective method of studying cultural eutrophication in the Manukau and similar harbours. Sediment particle size distribution was looked at and it was determined that sediments are extremely fine near the Manukau Sewage Oxidation Ponds, coarser but still muddy in most of the inlets of the Harbour, and sandy in most of the open Harbour intertidal flats remote from pollution sources. Counts of coliform bacteria were made and levels in intertidal sediments were found to be generally higher than in overlying waters but not less temporally variable. It was also determined that waters and sediments of the north-east region of the Harbour are of poor sanitary quality. Several management considerations are discussed in relation to the results of the study. Further research needs are outlined terms of 22 research projects addressed to waste water management, land erosion control, and tidelands managements.

No description available.

No description available.

Ecophysiological attributes could be causes for rarity in plants. We tested the hypothesis that a species’ ability to regulate photosynthesis and growth in response to environmental factors is indicative of its environmental resilience and that this is linked to its conservation status. In this study, the ecophysiology of Graptophyllum reticulatum, an Australian endangered endemic species, was compared with that of its three closely related and more common congeners G. ilicifolium, G. excelsum and G. spinigerum. Ecophysiological attributes were measured on the four species in their natural habitats and under artificially imposed environmental stresses, including changed soil conditions, excess light and low water availability, in a glasshouse experiment. Photosynthesis was determined at the photosystem II and leaf level using chlorophyll a fluorescence and gas exchange techniques. Applied to the chlorophyll fluorescence transient of leaves, the JIP test provides a Performance Index which quantifies the main steps in PSII photochemistry including light energy absorption, excitation energy trapping, and conversion of excitation energy into electron flow. At the leaf level, gas exchange measurements allow determination of maximum CO2 assimilation rates, intercellular CO2 concentrations, stomatal conductance for water vapour and instantaneous water use efficiency. Growth analysis was performed to assess relative growth rates and physiological and morphological responses. Analysis of physiological differences and responses indicated that, compared to its more common relatives, the endangered G. reticulatum was an intrinsically slow growing species, exhibited the lowest fitness when growing in favorable environments and was most sensitive to excess light stress. Photoinhibition is therefore likely to restrict the endangered species to shade habitats. Compared with the endangered G. reticulatum, the vulnerable G. ilicifolium and common G. spinigerum species were better adapted to high light and changed nutrient levels, but were more susceptible to water stress. The rare G. excelsum had the fastest growth rate and the highest fitness in favorable environments. Based on the ecophysiological attributes examined here, it is proposed that excess light is likely to be the most critical abiotic factor restricting distribution of the endangered species in a fragmented landscape. The survival of the species may be most dependent on the intactness of the habitat over-storey. In contrast, the vulnerable G. ilicifolium showed strong susceptibility to water limitation, and survival might be threatened if climate change alters habitat water relations to cause, for example, more pronounced dry periods. The rare G. excelsum which had highest carbon gain and growth in the experiments carried out in this study, may become the most successful adaptation out of the rainforest environment due to its tolerance to higher light and limited water availability. To examine the generality of the link between rarity and ecophysiology with Graptophyllum species, two dipterocarp species, narrowly endemic Dipterocarpus condorensis and local common Shorea roxburghii that are actually co-located in South-eastern Vietnam were studied. Findings in this case study confirmed the usefulness of the comparative approach based on physiological measurements, either in situ or ex situ, to explain plant rarity. The results of this study indicate ecophysiological research is a tool for examining causes of rarity and possible abiotic threats. The information gained allows assessment of environmental resilience of species and contributes essential knowledge for management and conservation of threatened plants. Such knowledge is also useful for ex situ conservation including propagation, translocation and re-introduction in restoration programs.

The Waikato river is one of the largest river in New Zealand. It emerges from Lake Taupo, which lies near the centre of the North Island, and flows in a northerly direction for approximately 322 km to discharge into the Tasman Sea at Port Waikato on the west coast. It falls about 366 m during its course, the greater part of which occurs in the first 200 km after it leaves the lake. Ridall (1967) has treated the Waikato river as originating between Ruapehu mountain and the Kaimanawa ranges, but considering, the multitude of other streams which flow into Lake Taupo and account for nearly 56% of the discharge from that lake into the Waikato, the question of the origin of the Waikato river upstream of Lake Taupo seems to be more academic than practical.

Whole document restricted, see Access Instructions file below for details of how to access the print copy. / The usefulness of pollinator syndromes as a predictor of pollination requirements, the factors that influence the effectiveness of pollinator and what determines fruit set and size were investigated in Feijoa sellowiana (Myrtaceae). Feijoa are grown commercially on a limited scale in New Zealand but development of the industry is hindered by low fruit set and a high degree of variability in size and shape of fruit. The plant was introduced from South America but little was known abut its reproductive biology or its pollination requirements and the development of current varieties has been largely by trial and error. This study aimed to redress this lack of knowledge. Investigation of floral architecture along with the use of controlled pollinations showed that feijoa flowers are hermaphroditic but exhibit spatial separation (herkogamy) and partial temporal separation (dichogamy) of female and male functions. Flowers are female first (protogynous) and receptivity declines soon after pollen dehiscence. As expected, outcrossed flowers are more likely to set fruit. Listing floral characteristics according to pollination syndromes led to the suggestion that wind was an unlikely pollen vector and that birds are more likely vectors than insects. The flowers are nectarless but offer two rewards in the form of pollen and large sugary petals. A wide range of insects and birds visit flowers and controlled pollination and the exclosure of trees were used to confirm the ineffectiveness of wind. Possession of sugary ,petals appears to be a unique animal attractant. Analysis of relative sugar levels in petals at different developmental stages showed that sugar levels are lowest in the bud stage but increase rapidly to peak at the time of pollen dehiscence when the flower is functionally both female and male. The sugar levels attained are comparable to those for nectar of bird visited flowers. A series of visual cues are available for birds to associate with reward differences. Birds do visit flowers and consume petals and petals were mostly eaten when sugar levels were highest but this depended on bird density. Moreover, sufficient petals were left after any visit to ensure revisitation. The effectiveness of the different floral visitors as pollinators was investigated by determining the number of pollen grains deposited and the time of deposition relative to receptivity. The behaviour of visitors at flowers, their, movements between flowers and trees and the use of partial exclosures were used to understand differences in effectiveness. Only large birds such as blackbirds (Turdus merula) and mynas (Acridotheres tristis) were effective pollinators of feijoa. Visits by insects and small birds resulted in the transferral of minimal pollen. Not only did large birds transfer more pollen per visit, they also moved larger distances and so were more likely to outcross flowers. Results of self and cross pollinations early in the study led to the questioning of the status of some of the common cultivars. "Triumph" and "Mammoth" appear to be of mixed genetic origins whereas "Apollo" and "Gemini" respond as clonal cultivars. Only 39.5% of flowers matured fruit even though most were receiving sufficient pollen. The source of pollen affected fruit set markedly. Cultivars and different individuals showed a range of compatibilities. Most did not set fruit when selfed, some did but the fruit were small while a minority set large selfed fruit. Cross pollinations resulted in a range of responses similar to selfing. Fruit set and the morphology of pollen tubes shoed that feijoa possesses a gametophytic self-incompatibility (SI) mechanism. Analysis of covariance was used to demonstrate that both these pre-zygotic effects and post=zygotic investment due to paternity have significant effects on fruit size. Current ideas of mechanisms affecting the quality of offspring are discussed. The need to consider paternity is stressed. Ratios of pollen tubes reaching the ovary, the presence or absence of the 10 different shapes of callose plugs along with the ratios of two groupings of plug shapes, and of the length of callose plugs are shown to predict independently the outcome of pollinations. These are proposed as quick methods for screening the likely complimentarity of a large number of individuals. Finally, results from all aspects of the study are used to suggest ways to improve both present management and future development of feijoa as a commercial crop.