Thesis (doctoral)--Königliche Christian-Albrechts-Universität zu Kiel, 1910. / Lebenslauf. Includes bibliographical references.

Proefschrift--Leyden. / "Resumé" in French. "Literatuur": 1 leaf following p. 134. "Stellingen": 2 leaves at end.

Proefschrift--Leyden. / "Resumé" in French. "Literatuur": 1 leaf following p. 134. "Stellingen": 2 leaves at end.

No description available.

Inaugural dissertation (Ph. D.)--Universität Bern. / Includes bibliographical references.

The potential of kauri (Agathis australis) for paleoclimate research is well established. Multiple treering chronologies have been derived from living and sub-fossil material and growth-climate relationships have been identified. Work has progressed to the stage where raw ring-width data and chronologies covering the last half of the second millennium can confidently be placed in the public domain, to facilitate multiproxy paleoclimate studies. This paper outlines progress in deriving kauri tree-ring chronologies, summarises data availability and quality, and explores the scope for developing composite chronologies. Statistical quality control of the available data was undertaken, following application of an "optimum" standardisation technique. Variations in sample depth with time and between sites result in a complex evolving pattern of chronology quality across sites. Analysis of inter-site statistical relationships identified a pervasive regionalscale signal in kauri with some minor secondary patterns. In light of the strong common signal, a kauri master chronology was built by pooling tree-ring series. Analysis of the quality of this chronology indicates that high-quality master chronologies can be derived for A.D. 1597-1996 from as few as 25 trees from seven sites.

Considerable research has occurred in recent years to build Agathis australis (D. Don) Lindley (kauri) tree-ring chronologies for paleoclimate applications and to identify statistical relationships between kauri tree rings and climate. This paper reports on a multi-year study of the seasonal growth of kauri, designed to assist in the interpretation of identified statistical relationships, and to determine if kauri’s seasonal growth characteristics are dependent on tree size. To achieve this, 43 kauri (0.09-2.00 m diameter) at Huapai Scientific Reserve were fitted with vernier bands to measure circumference change over 3-4 growing seasons. Absolute (mm) and relative (proportion of total ring) monthly growth rates were calculated for each tree and statistics characterizing the timing of growth were calculated (e.g. date corresponding to 50% of growth). Tree size-related differences were assessed by splitting the data into three subsets based on size, then comparing the monthly growth rates and growth timing statistics for the subsets. The growth timing statistics were also correlated with tree diameter. A key finding is the strong dominance of spring growth, with October and November alone accounting for 38-50% of the total ring width. This result is consistent across age cohorts, although the largest trees tended to peak in November, rather than October. This indicates that kauri tree rings are likely to have value in terms of reconstructing spring conditions; consistent with reported statistical relationships between kauri tree rings and the El Niño-Southern Oscillation phenomenon. High inter-tree variance in growth rates characterized the results, but little of this variance was accounted for by tree size. Although relationships between tree size and growth characteristics were generally weak and inconsistent, they are considered sufficient to warrant a precautionary approach in the development of tree-ring chronologies for climate reconstruction purposes.

The traditional approach to standardizing tree-ring time series is to divide raw ring widths by a fitted curve. Although the derived ratios are conceptually elegant and have a more homogenous variance through time than simple differences, residual heteroscedasticity associated with variance dependence on local mean ring width may remain. Incorrect inferences about climate forcing may result if this heteroscedasticity is not corrected for, or at least recognized (with appropriate caveats). A new variance stabilization method is proposed that specifically targets this source of heteroscedasticity. It is based on stabilizing the magnitude of differences from standardization curves to a common reference local mean ring width and uses data pooled from multiple radii. Application of the method to a multi-site kauri (Agathis australis (D. Don) Lindley) data set shows that (a) the heteroscedasticity issue addressed may be generic rather than radius-specific, at least for some species, (b) variance stabilization using pooled data works well for standardization curves of variable flexibility, (c) in the case of kauri, simple ratios do not appear to be significantly affected by this cause of heteroscedasticity, and (d) centennial-scale variance trends are highly sensitive to the analytical methods used to build tree-ring chronologies.

The growth and productivity of kauri (Agathis australis (D. Don) Lindl.) in even-aged single-species planted stands and mixed-aged second-growth natural stands has been studied. Stand-level models of height, basal area and whole-tree volume were developed. Kauri growth and productivity in planted stands up to 83 years old were compared to that of natural stands that were up to 196 years of age. Within natural stands, the effect of thinning treatments on growth and productivity was also assessed. Models of growth and productivity were initially developed for each of the three different kauri stand types independently (planted, second-growth unthinned and thinned). Combined data sets allowed for the development of single models that were able to fit all stands. A Schumacher equation with local slope parameter and asymptote bounded at 45 m gave the best fit for height growth, while a von Bertalanffy-Richards equation in difference form with local slope parameter gave the best fit for basal area growth. Kauri in all stand types were found to be slow to establish with little height growth in planted stands for the first five years after planting, and for the first 25 years in natural stands. Similar trends were observed for basal area and whole-tree volume development. Models developed in this study are relevant only to kauri in the “ricker” or monopodial form irrespective of age, and for stands from 320-2000 stems/ha. Kauri growth and productivity in planted stands was substantively better than that in second-growth stands. Planted kauri had height increment of 0.4 m/yr for periods of up to 30 years. At age 50, planted kauri was predicted to be 20 m in height, over twice the height of kauri in natural stands, and to be 28.1 m by 100 years. Basal area at age 50 averaged 64.9 m2/ha for all planted stands, and was predicted to be 98.2 m2/ha at age 100. Whole-tree volume was predicted to increase by 11.7 m3/ha/annum for all stands, but was as high as 20.6 m3/ha/yr in one 70 year old stand. The maximum productivity of kauri was observed in one high-performing young kauri planted stand where whole-tree volume increment in excess of 30 m3/ha/yr were predicted for a period from age 15-30. Carbon sequestration was calculated from the volume model and predicted to be 316 t C/ha and 1168 t CO2/ha at age 100. Mortality of kauri in planted stands was as high as 3.9%/yr for individual stands, over their entire rotation to date. For all stands, mortality averaged 0.56%/yr. The highest mortality occurred in the years before the first assessment and averaged 0.64%/yr for all stands. From the first to the last assessment mortality averaged 0.30%/yr. Where mortality in individual stands was above the average rate the dominant cause was drought. The growth and productivity of kauri in second-growth stands was only marginally improved by thinning to reduce competition. The volume removed in thinning operations had not been replaced in the (up to) 50 years since thinning treatments were applied. At age 150, the predicted height of kauri in unthinned control and thinned stands were identical at 25.9 m. Basal area at age 150 was 64.5 m2/ha in unthinned stands and 52.6 m2/ha in thinned stands. Whole-tree volume was predicted to be 681 m3/ha in unthinned and 549 m3/ha in thinned stands. Volume increment peaked at 5.2 m3/ha/yr in unthinned stands and 4.7 m3/ha/yr in thinned stands. This study has shown that the worst growth and productivity of kauri in planted stands was better than that of the best natural stands. The difference in performance between plantation and second-growth kauri was most likely a result of a combination of lower site quality characteristics (soil type and fertility), stand structure and within-stand competition of natural stands. The data for planted kauri came from 31 permanent sample plots located in 25 planted stands. These stands ranged in age from 14-83 years at the last assessment, and ranged in stand density from 218-1800 stems/ha. The overall number of planted stands and plots from which data was available to develop models was small in comparison to many exotic forest species datasets. The majority of the planted stands were not silviculturally treated after planting, and considerable variation in establishment methods was recorded. The results of productivity from the models developed for planted kauri should therefore be considered to be conservative. The results of this study indicate an opportunity to grow kauri in plantations on good quality sites for the production of high quality sapwood timber over rotations of 60 years or less. They also indicate that second-growth stands will produce usable volumes of timber, but only over extended periods of time. To ensure that kauri in planted stands can meet the potential observed during the development of these models, a series of well-managed stands on a range of sites is urgently required where the effects of timely silviculture, including initial stand density, can be assessed, quantified and reported on. Further research on selection and breeding for the species would improve the early establishment and growth of planted kauri resulting in a reduced rotation length. Research on long-term management strategies that include continuous cover forestry may make the species an attractive proposition for carbon forestry and/or for the production of high quality, naturally durable heartwood. The dataset compiled for this study was the best data available. While it cannot as yet be used to develop prescriptions for the establishment and maintenance of planted kauri stands, it does provide clues and directions that should be pursued in further research, however.

Replication is a key principle in tree-ring research. Dendrochronologists strive to maximise sample size to enhance the "signal" in tree-ring chronologies, often relying on crossdating to provide an effective quality control filter. However, is crossdating alone a sufficient quality test for incorporating a series into a site chronology? We address this question using an objective and automated "chronology stripping" method designed to maximise the chronology's "Expressed Population Signal" (EPS), by iteratively removing series which lower chronology EPS. A 15-site data set of Agathis australis (D. Don) Lindley is used to demonstrate the method. Results suggest that modest benefits may be gained by chronology stripping, but the quality control implicit in crossdating is indeed effective, at least for Agathis australis.