Thesis (MSc)--Stellenbosch University, 2004. / Full text to be digitised and attached to bibliographic record. / ENGLISH ABSTRACT: The control of excessive vegetative growth is important in deciduous fruit orchards. Currently the plant growth regulator prohexadione-calcium (p-Ca) is used to control apple shoot growth in the Untited States of America and some European countries. The effect of P-Ca on the shoot and fruit growth of apples (Malus domestica B.), pears (Pyrus cummunis L.), plums (Prunus sa/icina L.) and nectarines (Prunus persica L.) was evaluated. Inhibition of shoot growth can effect fruit growth. Therefore I did a literature review on the fruit growth of pome- and stone fruit. Split pit, a physiological disorder associated with an increased fruit growth rate in stone fruit, was also investigated. During the course of the 2001 / 2002 season two trials were conducted in the Villiersdorp area of the Western Cape on 'Golden Delicious' and 'Granny Smith' apple trees. Single and multiple applications of P-Ca at different rates, with and without the surfactant Dash®, were applied. One of these trials was continued during the 2002 / 2003 season. In the 2001 / 2002 season, P-Ca reduced shoot growth in both trials on 'Golden Delicious'. The shoot growth of 'Granny Smith' was reduced in both trials where PCa was applied three or four times. There was an improvement in the fruit size of 'Golden Delicious' in both trials, but there was no improvement in the fruit size of 'Granny Smith'. In the 2002 / 2003 season, the single P-Ca application did not reduce shoot growth. Unfortunately 'Golden Delicious' was harvested before any data were obtained. Once again P-Ca had no effect on the fruit size of 'Granny Smith'. Dash® did not improve the effect ofP-Ca. In the 2002 / 2003 season we replicated one trial on five different pear cultivars in the Wolsely area of the Western Cape. Single and multiple applications of P-Ca at different rates were compared to a girdling treatment (2 weeks after full bloom). 'Early Bon Chretien', 'Rosemarie', 'Flamingo', 'Forelle' and 'Packham's Triumph' pear trees were used and Dash®was added to all 0f the treatments. P-Ca reduced shoot growth in all of the pear cultivars. Girdling reduced shoot growth only in 'Forelle'. P-Ca increased fruit set of 'Early Bon Chretien', 'Rosemarie' and 'Forelle', however, this was associated with a reduced fruit size of 'Early Bon Chretien' and 'Rosemarie'. Girdling did not increase fruit set, but increased fruit size of 'Flamingo' and 'Early Bon Chretien'. P-Ca reduced return bloom of 'Packham's Triumph' and 'Forelle', whereas girdling increased return bloom in all the cultivars except 'Packham's Triumph'. In the 2002 / 2003 season, trials were also conducted on 'Pioneer' and 'Songold' plums and 'May Glo' nectarine in the Wemmershoek and Stellenbosch area of the Western Cape. Single applications at different rates of P-Ca were applied. Dash® was added to all of the treatments. The higher rates of P-Ca reduced the shoot growth of 'Pioneer'. P-Ca only reduced shoot growth of 'Songold' initially and but did not reduce shoot growth of 'May Glo'. P-Ca had no influence on fruit size of 'Pioneer', 'Songold' or 'May Glo'. P-Ca did not aggravate the occurrence of split pit. In conclusion, P-Ca reduced shoot growth in apples and pears when applied at the appropriate rates. Although P-Ca reduced shoot growth of 'Pioneer' plum, more research needs to be done on stone fruit to optimise timing and rate of P-Ca applications. / AFRIKAANSE OPSOMMING: Die beheer van oormatige lootgroei is van kardinale belang in vrugtebome. Tans word die plantgroeireguleerder proheksadioon-kalsium (P-Ca) gebruik om die lootgroei van appels te beheer in die Verenigde State van Amerika en sekere lande in Europa. Die effek van P-Ca op lootgroei en vruggrootte is in proewe op appels (Malus domestica B.), pere (Pyrus cummunis L.), pruime (Prunus salicina L.) en nekatriens (Prunus persica L.) geëvalueer. Aangesien lootgroei inhibisie moontlik vruggroei kan vesnel, is 'n literatuurstudie oor die vruggroei van kern-en steenvrugte gedoen. Die ontwikkelling van gesplete pit by steenvrugte ('n fisiologiese defek geassosieer met versnelde vruggroei) is ook ondersoek. Gedurende die 2001 / 2002 seisoen is P-Ca in twee afsonderlike proewe in die Villiersdorp area van die Wes Kaap geëvalueer. Enkel en veelvuldige toedienings van verskeie konsentrasies P-Ca, met en sonder die benatter Dash", is op 'Golden Delicious' en 'Granny Smith' bome toegedien. Een proef is herhaal gedurende die 2002 / 2003 seisoen. In die 2001 /2002 seisoen het die P-Ca behandelings in beide proewe die lootgroei van 'Golden Delicious' verminder. Die lootgroei van 'Granny Smith' is in beide proewe verminder waar P-Ca 3 of 4 keer toegedien is. Die vruggrootte van 'Golden Delicious', maar nie 'Granny Smith' nie, is in beide proewe deur die P-Ca verbeter. In die 2002 / 2003 seisoen kon die enkeltoedienings van P-Ca nie die lootgroei verminder van 'Golden Delicious' of 'Granny Smith' nie. 'Golden Delicious' is geoes voor enige inligting oor die vruggrootte ingesamel kon word. Weereens het PCa geen invloed op die vruggrootte van 'Granny Smith' gehad nie. Dash® het nie die effek van P-Ca verbeter nie.In die 2002 / 2003 seisoen is proewe met P-Ca gedoen op 5 verskillende peer kultivars in die Wolsely area van die Wes Kaap. P-Ca is teen verskillende konsentrasies, met enkel en veelvuldige bespuitings toegedien en vergelyk met 'n ringelerings behandeling (2 weke na volblom). 'Early Bon Chretien', 'Rosemarie', 'Flamingo', 'Forelle' en 'Packham's Triumph' bome is gebruik en die benatter Dash® is by al die behandelings gevoeg P-Ca toedienings het lootgroei verminder in 'Early Bon Chretien', 'Rosemarie', 'Flamingo', 'Forelle' en 'Packham's Triumph'. Ringelering kon slegs die lootgroei van 'Forelle' verminder. P-Ca het die vrugset van 'Early Bon Chretien', 'Rosemarie'en 'Forelle' verhoog. Die toename in vrugset het gelei tot 'n afname in die vruggrootte van 'Early Bon Chretien' en 'Rosemarie'. Ringelering het die vruggrootte van 'Flamingo' en 'Early Bon Chretien' verbeter. P-Ca het 'n afname in die hoeveelheid reproduktiewe knoppe in die volgende seisoen, van 'Packham's Triumph' en 'Forelle' veroorsaak. Ringelering het 'n toename in die hoeveelheid vegetatiewe knoppe in die volgende seisoen gehad vir al die kultivars, behalwe 'Packham's Triumph'. Geduerende dieselfde seisoen is daar ook proewe gedoen op 'Pioneer' en 'Songold' pruime en 'May Glo' nektarienbome in onderskeidelik die Wemmershoek en Stellenbosch areas van die Wes Kaap. Bome is met enkel toedienings van verskillende konsentrasies P-Ca behandel en die benatter Dash® is by al die behandelings bygevoeg. Die hoër dosisse P-Ca het die lootgroei van 'Pioneer' verminder. P-Ca kon slegs die aanvanklike lootgroei op 'Songold' verminder en kon nie lootgroei van 'May Glo' beperk nie. P-Ca het geen invloed op die vruggrootte van 'Pioneer', 'Songold' of 'May Glo' gehad nie. P-Ca het nie die voorkoms van gesplete-pit vererger nie. Om saam te vat kan gesê word dat P-Ca lootgroei op appels en pere goed beperk teen die regte konsentrasies. Alhoewel P-Ca lootgroei suksesvol beheer het op 'Pioneer', moet daar meer werk gedoen word op steenvrugte.

Thesis (MScAgric)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: Excessive shoot growth of fruit trees may have various negative effects. These include a decrease in fruit set, fruit size, red colour and in return bloom. Cultural practices that are currently in use, such as the use of dwarfing rootstocks, girdling and pruning do not always give sufficient shoot growth control. The use of plant growth retardants, in combination with these cultural practices, offer additional possibilities. Trials were conducted to evaluate the effect of the new plant growth retardant prohexadione-calcium (P-Ca) on apple, pear and plum shoot growth. In addition, the effect of P-Ca on fruit set, fruit size, yield, fruit quality and return bloom were also evaluated. During the 1999/2000 season P-Ca was applied to full bearing twelfth leaf 'Golden Delicious' trees on M793 rootstock, twenty-sixth leaf 'Granny Smith' trees on seedling rootstock, ninth leaf 'Royal Gala' trees on M793 rootstock, seventh leaf 'Rosemarie' trees on seedling rootstock and eighth leaf 'Songold' trees on 'Marianna' rootstock in the Villiersdorp area in the Western Cape (33°59' S, 19°17' E; ca. 365 m a.s.l.; Mediterranean climate). P-Ca was applied at concentrations of 3 x 50, 4 x 50 and 3 x 67 mg.l' to the apple trees. The first application was at petal drop with no surfactant added with any of the treatments. P-Ca was applied at concentrations of2 x 62.5,125,250 and 2 x 125 mg.l" to the pear and plum trees. The first application was at petal drop and pit-hardening for the pear and plum trees respectively. Agral-90 was used as surfactant only with the first spray applied to the pear trees. During the 2000/2001 season the same 'Golden Delicious' and 'Royal Gala' trees were used as in the 1999/2000 season. Thirteenth leaf 'Granny Smith' trees on M793 rootstock in the Villiersdorp area were used. Sixth leaf 'Rosemarie' trees on BP3 rootstock, fifth leaf 'Golden Russet Bose' trees on BP3 rootstock, seventh leaf 'Forelle' trees on BP3 rootstock and 16th leaf 'Packham's Triumph' trees on seedling rootstock in the Wolseley area in the Western Cape were used. P-Ca was again applied at concentrations of 3 x 50,4 x 50 and 3 x 67 mg.l' to the apple trees. The first application in the 'Golden Delicious' and 'Granny Smith' trees was at full bloom and at petal drop in the 'Royal Gala' trees. The last application was at 45 days before harvest. No surfactant was added with any of the sprays. P-Ca was applied at concentrations of 50, 75, 150, 2 x 50,2 x 75 and 3 x 50 mg.l" to the pear trees with the first spray when 4 to 5 leaves were unfolded and the last one 45 days before harvest. Agral-90 was added as surfactant with all the pear sprays. The pear trial also included a girdling treatment. P-Ca effectively inhibited shoot growth of all three apple cultivars in both seasons. Regrowth occurred in both seasons in all the cultivars, therefore it is not clear which treatment(s) is optimal for reducing shoot growth. P-Ca increased fruit size in 'Royal Gala' in the 1999/2000 season and decreased yield expressed as kg fruit harvested 1 em trunk circumference in 'Golden Delicious' in the 2000/2001 season. This reduction in yield can be attributed to the low number of flower clusters in the spring of 2000 following P-Ca treatment in 1999. P-Ca decreased the number of developed seeds in 'Royal Gala' in both seasons and increased the number of seeds with aborted embrios in the 200012001 season. After four weeks of cold storage (± 5°C) and one week at room temperature (± 20°C), P-Ca had no effect on the occurrence of bitter pit in 'Golden Delicious'. The 'Granny Smith' trees were harvested before fruit analysis could be done in the 2000/2001 season. In pear, girdling was not effective in inhibiting shoot growth in any of the cultivars, but P-Ca proved to be an effective inhibitor of shoot growth of 'Rosemarie' and 'Golden Russet Bose', and to a lesser degree 'Packham's Triumph', but not 'Forelle'. Despite the re-growth that occurred ca. four weeks after harvest in 'Rosemarie' in the 2000/20001 season, it appears that a single high rate (250 and 150 mg.l' for the 1999/2000 and 2000/2001 seasons respectively) P-Ca application is more effective than a single low rate or multiple low rates in inhibiting shoot growth. In the 200012001 season P-Ca increased fruit set in 'Rosemarie' and 'Forelle'. In both seasons P-Ca reduced 'Rosemarie' fruit size while girdling increased 'Forelle' and 'Packham's Triumph' fruit size in 2000/2001. P-Ca increased 'Rosemarie' fruit firmness and 'Forelle' fruit colour in the 2000/2001 season and decreased the percentage of 'Packham's Triumph' fruit with cork spot. Girdling increased 'Packham's Triumph' fruit colour and TSS concentration while decreasing fruit firmness in 2000/2001. P-Ca reduced return bloom in 'Forelle' and 'Packham's Triumph' in 2001, while girdling increased 'Golden Russet Bose' and 'Forelle' return bloom. Due to poor flowering and thus low fruit number in 'Golden Russet Bose', fruit set in 2000 could not be determined and no fruit analysis could be done. In 'Songold' all four P-Ca treatments inhibited shoot growth, but the 2 x 125 mg.l' treatment were the most effective, both in terms of total shoot growth and in reduction of the re-growth that occurred ca. two weeks before the first commercial harvest date. P-Ca increased fruit firmness and decreased TSS concentration both at harvest and after four weeks of cold storage at dual temperature (10 days at -O.soC + 18 days at 7.S°C). In conclusion P-Ca is an effective inhibitor of shoot growth of the apples 'Golden Delicious', 'Granny Smith' and 'Royal Gala', the pears 'Rosemarie', 'Golden Russet Bose' and 'Packham's Triumph' and the plum 'Songold', but more work is needed to control re-growth. / AFRIKAANSE OPSOMMING: Oormatige lootgroei van vrugtebome kan verskeie negatiewe effekte tot gevolg he, insluitende 'n afname in vrugset, vruggrootte, rooi kleur en 'n verlaging in die daaropvolgende jaar se blom. Boordpraktyke soos die gebruik van dwergende onderstamme, ringelering en snoei, beheer nie altyd lootgroei doeltreffend nie. Die gebruik van groeireguleerders, in kombinasie met hierdie boordpraktyke, bied bykomende geleenthede. Proewe is uitgevoer om die effek van die nuwe groeireguleerder proheksadioon-kalsium (PCa) op appel, peer en pruim lootgroei te evalueer. Die effek van P-Ca op vrugset, vruggrootte, opbrengs, vrugkwalitiet en die daaropvolgende jaar se blom is ook geevalueer. Gedurende die 1999/2000 seisoen is P-Ca toegedien aan voldraende twaalfde blad 'Golden Delicious' bome op M793 onderstamme, ses-en-twintigste blad 'Granny Smith' bome op saailing onderstamme, negende blad 'Royal Gala' bome op M793 onderstamme, sewende blad 'Rosemarie' bome op saailing onderstamme en agste blad 'Songold' bome op 'Marianna' onderstamme in die Villiersdorp area in die Wes Kaap (33°25' S, 19°12' 0; ligging ong. 270 m.; Meditereense klimaat). P-Ca is aan die appelbome toegedien teen konsentrasies van 3 x 50, 4 x 50 en 3 x 67 mg.l' met die eerste toediening by blomblaarval. Geen benatter is by enige van die toedienings gevoeg nie. P-Ca is aan die peer- en pruimbome toegedien teen konsentrasies van 2 x 62.5, 125, 250 en 2 x 125 mg.l' met die eerste toediening by blomblaarval en pitverharding vir onderskeidelik die peer- en pruimbome. Agral-90 is as benatter gebruik slegs saam met die eerste toediening op die peerbome. Tydens die 2000/2001 seisoen is dieselfde 'Golden Delicious' en 'Royal Gala' bome gebruik as in die 1999/2000 seisoen. Derde blad 'Granny Smith' bome op M793 onderstamme in die Villiersdorp area is gebruik. Sesde blad 'Rosemarie' bome op BP3 onderstamme, vyfde blad 'Golden Russet Bose' bome op BPI onderstamme, sewende blad 'Forelle' bome op BP3 onderstamme en sestiende blad 'Packham's Triumph' bome op saailing onderstamme in die Wolseley area in die Wes Kaap is gebruik. P-Ca is weereens aan die appelbome toegedien teen konsentrasies van 3 x 50, 4 x 50 en 3 x 67 mg.l". Die eerste toediening aan die 'Golden Delicious' en 'Granny Smith' bome was by volblom en die eerste toediening aan die 'Royal Gala' bome by blomblaarval. Die laaste toediening is 45 dae voor oes gedoen. Geen benatter is met enige van die toedienings bygevoeg nie. P-Ca is aan die peerbome toegedien teen konsentrasies van 50, 75, 150,2 x 50, 2 x 75 en 3 x 50 mg.l' met die eerste toediening toe vier tot vyf blare ontvou was en die laaste een 45 dae voor oes. Agral-90 is as benatter gebruik met al die peer bespuitings. By die peer proef is ook 'n ringeleer behandeling ingesluit. In beide seisoene het P-Ca die lootgroei van al drie appel kultivars verminder. Hergroei het in beide seisoene in al drie kultivars plaasgevind. Dit is dus onduidelik watter behandeling(s) optimaal is vir lootgroei beheer. In die 1999/2000 seisoen het P-Ca 'Royal Gala' vruggrootte verbeter. In die 2000/2001 seisoen is 'Golden Delicious' opbrengs, uitgedruk as kg vrugte geoes / cm stamomtrek, verlaag. Hierdie verlaging in opbrengs kan toegeskryf word aan die lae blom aantal in die lente van 2000 wat gevolg het op die P-Ca behandeling in 1999. In beide seisoene het P-Ca die aantal ontwikkelde sade in 'Royal Gala' verminder terwyl die aantal sade met geaborteerde embrios verhoog is in die 2000/2001 seisoen. Na vier weke koelopberging (± 5°C) en een week by kamertemperatuur (± 20°C) het P-Ca geen effek op die voorkoms van bitterpit in 'Golden Delicious' gehad nie. Die 'Granny Smith' bome is in die 2000/2001 seisoen geoes voordat enige data ingesamel kon word. Ringelering het geen effek op lootgroei gehad in enige van die peer kultivars nie, maar P-Ca het lootgroei effektief beheer in 'Rosemarie' en 'Golden Russet Bose' en tot 'n mindere mate 'Packham's Triumph', maar het geen effek op 'Forelle' lootgroei gehad nie. Ten spyte van die hergroei wat voorgekom het in die 'Rosemarie' bome ongeveer vier weke na oes in die 2000/2001 seisoen, wil dit voorkom asof P-Ca toegedien teen 'n enkele hoe konsentrasie (250 en 150 mg.l' vir die 1999/2000 en 2000/2001 seisoene onderskeidelik) meer effektief was om lootgroei te beheer as 'n enkele lae konsentrasie of veelvuldige lae konsentrasies. P-Ca het vrugset in 'Rosemarie' en 'Forelle' verhoog in die 2000/2001 seisoen. In beide seisoene het P-Ca 'Rosemarie' vruggrootte verlaag terwyl ringelering 'Forelle' en 'Packham's Triumph' vruggrootte verbeter het in die 2000/2001 seisoen. P-Ca het 'Rosemarie' vrugfermheid en 'Forelle' vrugkleur verhoog in die 2000/2001 seisoen en die aantal 'Packham's Triumph' vrugte met kurkvlek verlaag. Ringelering het 'Packham's Triumph' vrugkleur en TSSkonsentrasie verhoog, maar vrugfermheid verlaag in die 2000/2001 seisoen. P-Ca het die aantal blomme in 'Forelle' en 'Packham's Triumph' verlaag in 2001, terwyl ringelering blom in 'Golden Russet Bosc' en 'Forelle' verhoog het. As gevolg van 'n lae blom- en dus vruggetal in 'Golden Russet Bosc' kon vrugset In 2000 nie bepaal word nie en geen vrugontledings kon gedoen word nie. Al vier P-Ca behandelings het lootgroei in 'Songold' beheer, maar die 2 x 12S mg.l' toediening was die effektiefste, beide in terme van totale lootgroei en in beheer van die hergroei wat ongeveer twee weke voor die eerste kommersieele oesdatum plaasgevind het. PCa het vrugfermheid verhoog en die TSS-konsentrasie verlaag, beide tydens oes en na vier weke koelopberging by dubbel temperatuur (10 dae by -O.soC + 18 dae by 7.S0C). Om saam te vat kan gese word dat P-Ca 'n effektiewe inhibeerder van lootgroei van die appels 'Golden Delicious', 'Granny Smith' en 'Royal Gala', die pere 'Rosemarie', 'Golden Russet Bosc' en 'Packham's Triumph' en die pruim 'Songold' is. Meer werk is egter nodig om die hergroei te beheer.

In order to assess the enhancement of seedling survival and growth during drought conditions, five-hundred bare-root seedlings each of Shumard oak (Quercus shumardii Buckl.) and green ash (Fraxinus pennsylvanica Marsh.) were planted each with four soil amendments at a Wildlife Management Area in Lewisville, Texas. The treatments were a mycorrhizal inoculant, mulch fabric, and two superabsorbent gels (TerraSorb® and DRiWATER®). Survival and growth measurements were assessed periodically for two years. Research was conducted on vegetation, soil, and site history for baseline data. Both superabsorbent gels gave significant results for Shumard oak survival, and one increased green ash diameter. For overall growth, significant results were found among DRiWATER®, mycorrhizae, and mulch treatments.

Trees represent important living components in many urban parkland spaces. As living landscape entities, they have the capacity for potentially long life spans. As a result of these longevities, issues concerning tree death or senescence are not often engaged until the end of tree life spans have been reached, or are fast approaching. As organisms with finite life spans, tree senescence must be expected at some future point in time, and due consideration of this inevitable change is imperative within an urban parkland context. An understanding of tree longevity in urban parkland spaces must therefore be considered advantageous to subsequent design, management, and planning decisions enacted upon these landscapes. For appropriate decision-making to take place with regard to urban tree populations, figures reflecting expected tree longevity could purvey estimations of future tree senescence, and assist in providing practical information for all stakeholders of urban landscapes. In addition to this, developed models of parkland spaces supplying visual and spatial analysis of future tree senescence patterns could indicate potential landscape scenarios, and highlight tree populations most at risk of senescence within the near future. The development of models predicting possible future tree senescence patterns required a review of various fields of research in order to establish appropriate models for use, and to assign confidence levels based upon the knowledge of tree growth, longevity, and senescence in predicted landscapes. This thesis examined the subjects of tree longevity and senescence, with a particular focus upon the Adelaide Park Lands region in Adelaide, South Australia. Various tree growth parameters were collected from the field and combined with assigned tree ages to create matrix models that represented expected tree growth trends. Through the incorporation of curves fitted to these matrix models, tree ages could be assigned to tree specimens of unknown age, to determine dates of establishment based upon key growth parameters. Tree longevity figures for each taxon were sourced from a peer reference group survey conducted specifically for this purpose. Through the combination of calculated tree age and predicted tree longevity, senescence patterns for a region of the Adelaide Park Lands were modelled. Interactive structured query-based GIS software was incorporated to display these senescence patterns visually, and to provide interpretations of future landscape scenarios. Results obtained from the peer reference group survey provided a range of valuable figures representing expected tree longevities for 131 taxa from within the Adelaide Park Lands environment. These longevity figures, combined with matrix models and GIS simulations, revealed that considerable populations of established trees within Tuttangga/Park 17 in the Adelaide Park Lands are at a high risk of reaching senescence within the near future. / Thesis (Ph.D.) -- University of Adelaide, School of Architecture, Landscape Architecture, and Urban Design, 2008

Ecosystem-specific forest management requires comprehension of tree species productivity in managed settings, and how this productivity varies with the ecological determinants of site quality, i.e., the environmental factors that directly affect the growth of plants: light, heat, soil moisture, soil nutrients, and soil aeration. A good understanding of this variation is necessary for making species- and site-specific silvicultural decisions to maximize productivity. Productivity of a given species is usually measured by site index (tree height at 50 years at breast height age). Quantitative relationships between site index and these measures of site quality provide predictive models for estimating site index. Pacific silver fir (Abies amabilis (Dougl. ex Loud.) Forbes) is an important timber crop species in the coastal forests of British Columbia. In relation to climate, its range in southwestern British Columbia extends from sea level to almost timberline, and from the hypermaritime region on western Vancouver Island to the subcontinental region on the leeward side of the Coast Mountains. In relation to soils, its range extends from slightly dry to wet sites and from very poor to very rich sites. In view of this relatively wide climatic amplitude, a large variability in productivity can be expected. It is particularly important to consider the growth performance of Pacific silver fir when decisions are made regarding whether or not to cut stands on high-elevation sites. In the study summarized here, relationships between Pacific silver fir site index and selected ecological measures of site quality were examined, and site index models using these measures as predictors were developed.

Central to the issue of harvest feasibility on the outer BC coast (CWHvh) is the question of whether sites, once harvested, can be regenerated, and whether the time period for replacement and subsequent growth is economically and environmentally acceptable. Since low productivity sites have not been harvested in the past, there is a lack of data to answer this question. We tried to provide an answer by assessing regeneration following natural disturbances. Small scale gap disturbances are the norm within old-growth stands. If regeneration is not a problem in gaps, then we have some evidence that regeneration should not be a problem upon implementation of our management practices. The objectives of this study were: (1) to develop baseline information on the mechanisms and the patterns of regeneration across a sequence of forest types; (2) to assess regeneration success with respect to productivity; and (3) to estimate future growth and productivity.

Growth responses to climatic variables of red pine (Pinus resinosa Aiton) and Norway spruce (Picea abies L. Karst) were studied at the Morgan Arboretum, near Montreal, in southern Quebec, Canada (45$ sp circ$ 25$ sp prime$ N, 73$ sp circ$ 57$ sp prime$ W; 15.2 m above sea level). The relationships between climatic variables and basal area growth were examined using linear and quadratic models. Current and previous year's climatic variables were tested separately and in combination using multiple regression models. The best models explained 82% and 85% of the total variance of the growth of Norway spruce and red pine, respectively. The growth of both species was more associated with evapotranspiration than precipitation. The growth of Norway spruce was best explained by the current year's annual evapotranspiration (43%), while the growth of red pine was more related to previous year's August evapotranspiration (33%) at our site. / The JABOWA model was used to predict tree growth in hypothetical climates which could result from global climate changes. Based on literature, five treatments were applied: normal, and increases of 1, 3, 5, and 10$ sp circ$C. Comparison between the last (1983-1992) and next (1993-2002) ten years growth showed no significant differences between species when temperature was normal or increased by 1 and 3$ sp circ$C, but significant differences between species were observed when the temperature was increased by 5$ sp circ$C. Both species declined when the temperature was increased by 10$ sp circ$C. We concluded that Norway spruce is more sensitive to increases in atmospheric temperatures than red pine at our site.

No description available.

A stand-level growth and yield model was developed to predict future diameter distributions of thinned stands of mixed Appalachian hardwoods. The model allows prediction by species groups and diameter classes. Stand attributes ( basal area per acre, trees per acre, minimum stand diameter, and arithmetic mean dbh) were projected through time for the whole stand and for individual species groups. Future diameter distributions were obtained using the three-parameter Weibull probability density function and parameter recovery method. The recovery method used employed the first two non-central moments of dbh (arithmetic mean dbh and quadratic mean dbh squared) to generate Weibull parameters. Future diameter distributions were generated for the whole stand and every species group but one; the diameter distribution of the remaining species group was obtained by subtraction from whole stand values. A system of tree volume equations which allow the user t o obtain total tree volume or merchantable volume to any top height or diameter completes the model. Volumes can be calculated by species group and summed to get whole stand volume. / M.S.

Chan, Wing Shing. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 201-222). / Abstracts in English and Chinese. / Abstract --- p.i / Abstract (in Chinese) --- p.iv / Acknowledgements --- p.vi / Table of contents --- p.viii / List of tables --- p.xii / List of figures --- p.xiv / List of plates --- p.xvi / Chapter Chapter One --- Introduction / Chapter 1.1 --- Introduction --- p.1 / Chapter 1.2 --- Research background --- p.2 / Chapter 1.3 --- Conceptual framework --- p.6 / Chapter 1.4 --- Objectives of the study --- p.10 / Chapter 1.5 --- Significance of the study --- p.11 / Chapter 1.6 --- Organization of the thesis --- p.12 / Chapter Chapter Two --- Literature Review / Chapter 2.1 --- Land degradation: an overview --- p.14 / Chapter 2.2 --- Land degradation in Hong Kong --- p.17 / Chapter 2.3 --- Ecological rehabilitation --- p.20 / Chapter 2.4 --- Role of plantation in ecological rehabilitation --- p.22 / Chapter 2.5 --- Reforestation history in Hong Kong and species selection --- p.25 / Chapter 2.6 --- Nutrient requirements of native species --- p.31 / Chapter 2.7 --- The geology and soils of Hong Kong --- p.35 / Chapter 2.7.1 --- Geology --- p.35 / Chapter 2.7.2 --- Soils --- p.35 / Chapter 2.8 --- Greenhouse approach in nutrient requirement study --- p.37 / Chapter 2.9 --- Nitrogen mineralization --- p.38 / Chapter 2.10 --- Chlorophyll fluorescence --- p.40 / Chapter 2.11 --- Summary --- p.41 / Chapter Chapter Three --- Inherent Characteristics and Properties of Decomposed Granite and Fire-affected Soil / Chapter 3.1 --- Introduction --- p.42 / Chapter 3.2 --- Materials and methods --- p.42 / Chapter 3.2.1 --- Sources of soil and sampling --- p.43 / Chapter 3.2.2 --- Soil pre-treatment --- p.44 / Chapter 3.3 --- Laboratory analysis --- p.45 / Chapter 3.3.1 --- Reaction pH and conductivity --- p.45 / Chapter 3.3.2 --- Texture --- p.46 / Chapter 3.3.3 --- Organic carbon --- p.46 / Chapter 3.3.4 --- Total Kjeldahl nitrogen (TKN) --- p.47 / Chapter 3.3.5 --- Carbon: nitrogen ratio --- p.47 / Chapter 3.3.6 --- Total phosphorus (TP) --- p.47 / Chapter 3.3.7 --- Exchangeable Al and H --- p.48 / Chapter 3.3.8 --- "Exchangeable cations, base saturation percentage (BSP) and exchangeable Al percentage" --- p.48 / Chapter 3.4 --- Results and discussion --- p.49 / Chapter 3.4.1 --- Texture --- p.49 / Chapter 3.4.2 --- Reaction pH and conductivity --- p.49 / Chapter 3.4.3 --- "Soil organic matter, total Kjeldhal nitrogen and total phosphorus" --- p.51 / Chapter 3.4.4 --- Exchangeable cations --- p.52 / Chapter 3.4.5 --- DG as a representative soil of soil destruction sites --- p.54 / Chapter 3.4.6 --- FAS as a representative soil of vegetation disturbance sites --- p.56 / Chapter 3.5 --- Summary --- p.58 / Chapter Chapter Four --- Nitrogen Fluxes of Decomposed Granite and Fire-affected Soil Amended with Urea / Chapter 4.1 --- Introduction --- p.59 / Chapter 4.2 --- Materials and methods --- p.62 / Chapter 4.2.1 --- Experimental design --- p.62 / Chapter 4.2.2 --- Soil incubation and sampling --- p.63 / Chapter 4.2.3 --- Analysis of mineral nitrogen (NH4-N and NO3-N) --- p.64 / Chapter 4.2.4 --- Statistical analysis --- p.64 / Chapter 4.3 --- Results and discussion --- p.64 / Chapter 4.3.1 --- Variation of NH4-N in DG and FAS --- p.64 / Chapter 4.3.2 --- Variation of N03-N in DG and FAS --- p.68 / Chapter 4.3.3 --- Variation of mineral N in DG and FAS --- p.74 / Chapter 4.3.4 --- NH4-N fluxes in DG and FAS --- p.78 / Chapter 4.3.5 --- NO3-N fluxes in DG and FAS --- p.80 / Chapter 4.3.6 --- Mineral N fluxes in DG and FAS --- p.82 / Chapter 4.4 --- Summary --- p.86 / Chapter Chapter Five --- Growth Performance of Native Species in Decomposed Granite and Fire-affected Soil / Chapter 5.1 --- Introduction --- p.88 / Chapter 5.2 --- Materials and methods --- p.91 / Chapter 5.2.1 --- Experimental design --- p.91 / Chapter 5.2.2 --- Nitrogen treatments --- p.94 / Chapter 5.2.3 --- Post-planting care --- p.95 / Chapter 5.2.4 --- "Measurement of survival rate, height, basal diameter, aboveground biomass and foliar nitrogen" --- p.95 / Chapter 5.2.4.1 --- Survival rate --- p.96 / Chapter 5.2.4.2 --- Height and basal diameter --- p.96 / Chapter 5.2.4.3 --- Aboveground biomass --- p.96 / Chapter 5.2.4.4 --- Foliar sampling --- p.97 / Chapter 5.2.4.5 --- Determination of foliar nitrogen --- p.97 / Chapter 5.2.5 --- Statistical analysis --- p.97 / Chapter 5.3 --- Results and discussion --- p.98 / Chapter 5.3.1 --- Survival rate --- p.98 / Chapter 5.3.2 --- Height growth of species in DG --- p.105 / Chapter 5.3.3 --- Effect of nitrogen on species height growth in DG --- p.112 / Chapter 5.3.4 --- Height growth of species in FAS --- p.117 / Chapter 5.3.5 --- Effect of nitrogen on species height growth in FAS --- p.118 / Chapter 5.3.6 --- Effect of DG and FAS on species height growth --- p.120 / Chapter 5.3.7 --- Basal diameter growth of species in DG --- p.122 / Chapter 5.3.8 --- Effect of N on basal diameter growth of species in DG --- p.124 / Chapter 5.3.9 --- Basal diameter growth of species in FAS --- p.126 / Chapter 5.3.10 --- Effect of N on basal diameter growth of species in FAS --- p.127 / Chapter 5.3.11 --- Effect of DG and FAS on species basal diameter growth --- p.127 / Chapter 5.3.12 --- Overall height and basal diameter growth of species in DG . --- p.129 / Chapter 5.3.13 --- Overall height and basal diameter growth of species in FAS --- p.131 / Chapter 5.3.14 --- Aboveground biomass of species in DG --- p.133 / Chapter 5.3.15 --- Effect of N on aboveground biomass of species in DG --- p.135 / Chapter 5.3.16 --- Aboveground biomass production in FAS --- p.138 / Chapter 5.3.17 --- Effect of N on aboveground biomass of species in FAS --- p.139 / Chapter 5.3.18 --- Effect of DG and FAS on aboveground biomass of species --- p.141 / Chapter 5.3.19 --- Foliar nitrogen --- p.143 / Chapter 5.3.19.1 --- Foliar N of species grown in DG --- p.143 / Chapter 5.3.19.2 --- Effect of N amendment on foliar N of species in DG --- p.147 / Chapter 5.3.19.3 --- Foliar N of species in FAS --- p.149 / Chapter 5.3.19.4 --- Effect of N amendment on foliar N of species in FAS --- p.151 / Chapter 5.3.19.5 --- Effect of DG and FAS on the foliar N of species --- p.152 / Chapter 5.4 --- Summary --- p.155 / Chapter Chapter Six --- Photosynthetic Efficiency of Native Species / Chapter 6.1 --- Introduction --- p.158 / Chapter 6.2 --- Materials and methods --- p.160 / Chapter 6.2.1 --- Measurement of chlorophyll fluorescence --- p.160 / Chapter 6.2.2 --- Statistical analysis --- p.162 / Chapter 6.3 --- Results and discussion --- p.162 / Chapter 6.3.1 --- Photosynthetic efficiency of species in DG --- p.162 / Chapter 6.3.2 --- Photosynthetic efficiency of species in FAS --- p.170 / Chapter 6.3.3 --- Effect of DG and FAS on photosynthetic efficiency of Species --- p.172 / Chapter 6.4 --- Summary --- p.175 / Chapter Chapter Seven --- Conclusions / Chapter 7.1 --- Introduction --- p.178 / Chapter 7.2 --- Summary of major findings --- p.179 / Chapter 7.3 --- Implications of the study --- p.187 / Chapter 7.3.1 --- Species selection for the rehabilitation of soil destruction sites --- p.187 / Chapter 7.3.2 --- Species selection for the rehabilitation of vegetation disturbance sites --- p.191 / Chapter 7.3.3 --- Fertilization practice in different degraded lands --- p.193 / Chapter 7.3.4 --- The importance of soil test in ecological rehabilitation Planting --- p.195 / Chapter 7.4 --- Limitations of the study --- p.197 / Chapter 7.5 --- Suggestions for further study --- p.198 / References --- p.201 / Appendices --- p.223