Evaluation of Eucalyptus red gum species and provenances for inland humid subtropical regions of southern China

There is a long history of eucalypt planting in inland regions of southern China where humid summers and frequent winter frosts and extreme cold events are features of the climate. Although early eucalypt plantings suffered widespread failures, some species managed to survive with individual trees in some plantings growing to impressive sizes with diameter at breast height (DBH) exceeding 50 cm. One of the most productive and best adapted species in the plantings was Eucalyptus camaldulensis. Two species–provenance trials were established in southern and central Hunan province in 2006 primarily to explore the potential of E. camaldulensis and the related E. tereticornis, but also to provide comparisons with two other species with potential for the climate. The trials included 65 provenances representing six taxa from four species: E. camaldulensis, E. tereticornis, E. amplifolia and E. macarthurii. Three provenances represented improved seed sources from Africa, whilst the others were natural stand provenances. Eucalyptus amplifolia var. amplifolia demonstrated the best potential for growth and survival up to age 5 years. Eucalyptus macarthurii had the best cold tolerance, but relatively poor performance for growth and survival. Both E. tereticornis and E. camaldulensis demonstrated reasonable cold tolerance, but growth and survival of E. camaldulensis var. camaldulensis provenances from temperate to subtropical climatic areas with dry summers and winter-dominant rainfall (Köppen climate classification Csa) were markedly inferior than those of E. tereticornis ig. ‘tereticamal’ and E. tereticornis ssp. tereticornis sourced from tropical and subtropical environments with summer-dominant rainfall (Köppen climate classifications Aw and Am). Seedlots of E. camaldulensis, E. tereticornis and E. macarthurii from improvement programs in Zimbabwe and South Africa mostly proved inferior to or no better than the best natural stand provenances of the same species in the Hunan environment.     

Selection of cold-tolerant Eucalyptus species and provenances for inland frost-susceptible,humid subtropical regions of southern China

Inland humid subtropical regions of China’s southern provinces have substantial areas of land potentially available for forest plantation development. Such development would help address a substantial deficit in domestic production compared with demand for timber and fibre raw materials. However, the tropical and subtropical eucalypt varieties that are the basis of highly productive and commercially successful plantations in China’s warmer coastal regions have proved poorly adapted to inland regions which are characterised by hot humid summers and frequent winter frosts and cold events with temperatures down to –8°C or lower.

To evaluate a range of Eucalyptus species and provenances for plantation development in this subtropical environment, three species–provenance trials were established in southern and central Hunan province from 2001 to 2004. Included in these trials were 64 provenance seedlots representing 22 species and a locally selected Eucalyptus camaldulensis clone. Five of these seedlots represented somewhat improved sources from South Africa, whilst the others were unimproved natural stand provenances. Species that demonstrated the best growth and survival at age 6 years were E. amplifolia var. amplifolia, E. benthamii, E. dunnii and E. dorrigoensis. Species which showed reasonable performance in at least one trial and warrant further investigation include E. saligna × E. botryoides and E. deanei. Whilst E. macarthurii had the best cold tolerance, it had relatively poor performance for growth and survival. Provenances from imported improved sources (from South Africa) in most cases proved inferior to, or no better than, the best natural-stand provenances of the same species, providing salutary guidance for prospective growers.     

Eleventh Commonwealth Forestry Conference—Trinidad and Tobago

Sixty-nine Eucalyptus amplifolia seedlots (four previously tested provenances and 65 half-sib progenies from selected trees in 11 Australian provenances) were established in September 1986 at Gainesville, Florida, measured periodically for growth and frost-tolerance, and converted in August 1989 to a seedling seed orchard on the basis of sib and individual superiority. Provenance variability was significant for seedling and second-coppice survivals but especially for frost-tolerance. The provenances represented by the 65 progenies were notably better than previously tested provenances. No new provenance was superior in all critical traits, but each had at least one progeny with good tree size and acceptable frost-tolerance. Individual and family heritabilities were moderate, and seedlings from the seed orchard should have about 30% better growth and frost-tolerance. Selected progenies also performed well in additional field studies. The resilience of E. amplifolia progenies in a freezing chamber test exceeded that of four other Eucalyptus species. Clonal propagation appears possible, but the rooting abilities of cloning candidates varied around a mean of 40%, and micropropagation was hampered by contamination. Additional emphases on importation of new provenances, artificial frost screening, and clonal propagation are suggested.     

Growth of Eucalyptus pellita and E. urophylla and effects on pasture production on the coastal lowlands of tropical northern Australia

Eucalyptus pellita F. Muell. and E. urophylla S. T. Blake are important timber species which have potential for wood production in plantation and agroforestry systems in humid northern Queensland. This study was established to examine two provenances of each species on a coastal lowland site, using randomised complete block design. Survival, height, diameter at breast height (DBH), bole length and tree form were measured at ages 12, 24 and 39 months. The height and biomass of the pasture underneath each provenance plot were also measured at 39 months. Significant differences occurred in most of the tree characteristics at 39 months. Differences in pasture growth, on the other hand, were not significant. Compared with the two E. pellita provenances, the provenances of E. urophylla had superior height and DBH growth but had worse form. Overall, however, both species had high survival, fast growth, satisfactory form, and minimal effects on pasture growth. Although all four taxa appear to be suitable for silvopastoral systems, further trials involving more provenances on a wider range of sites are recommended to establish the environmental and economic limits for the use of these species.     

Growth and form of provenances of Eucalyptus saligna at Wondo Genet,southern Ethiopia

A trial testing 10 provenances from across the natural range of Eucalyptus saligna and a local land race was established at Wondo Genet, southern Ethiopia. Eight years after planting, survival, tree height, diameter at breast height over bark, stem form, number of forks, height to the first fork, number of branches, branch diameter and branch angle were assessed. Volume per hectare was also calculated. Survival ranged between 36% (a provenance from 87 km north of Windsor, NSW) and 79% (Consuelo Tableland, Queensland), and differences were significant (P < 0.05). Among morphological characteristics, only the number of branches showed significant variation (P < 0.05), with the greatest number (12.4) being recorded for the Bulahdelah, NSW, provenance and the least (8.5) for the Clyde River, NSW, provenance. Major growth and morphological parameters (tree height, diameter, volume and stem form) did not differ significantly. The overall volume production (mean annual increment 26.4 m³ ha^?1) was well above the minimum acceptable growth observed on good sites elsewhere. Differences between provenances were small and mostly not significant, and no pattern of geographic variation was detected. Given the acceptable mean annual increment, those provenances represented by an adequate number of parent trees could be maintained for further selection and breeding, and to maintain genetic diversity of the species in Ethiopia.     

Comparative early growth of Eucalyptus species of the subgenera Monocalyptus and Symphyomyrtus in intensively-managed plantations in southern Tasmania

Four eucalypt species. Eucalyptus delegatensis, E. globulus, E. nitens and E. regnons were established at each of four plantations situated between 60 m and 650 m asl in SE Tasmania. E. grandis and E. pauciflora were also established at the lower and upper two plantations respectively. Each plantation was managed intensively through the application of fertiliser and pest control. There were large differences in height and diameter growth between ages I and 5 years between subgenera, species and provenances. In general, E. globulus and E. nitens of subgenus Symphyomyrtus grew faster than E. delegatensis and E. regnans of subgenus Monocalyptus. Survival was also greater in Symphyomyrtus than Monocalyptus species except at the uppermost (650 m) site where snow and frost killed E. globulus. The faster diameter growth across all sites at age 5 years was from the Upper Toorongo provenance of E. nitens with mean diameters at breast height between 9.6 and 10.5 cm; the tallest species. 11.1 m was the Otways provenance of E. globulus at 240 m.

Annual increments of both Symphyomyrtus species compared favourably with those obtained under management for high yield elsewhere in Australia.     

Nine year results from a Eucalyptus camaldulensis Dehnh. provenance trial in the Wellington catchment of Western Australia

Data for 20 provenances of Eucalyptus camaldulensis from the southern half of Australia including 14 provenances of variety camaldulensis and 6 provenances of variety obtusa were assessed for growth and form in the south west of Western Australia. Mean annual volume increment at age nine years was greater in variety camaldulensis (3.3 m³ ha^?1 yr^?1) than for variety obtusa (1.9 m³ ha^?1 yr^?1). No significant differences in forking or branching were found between the two varieties. Lake Albacutya (variety camaldulensis) was the most productive provenance yielding 5.3 m³ ha^?1 yr^?1 but was only average for form. Laura (variety camaldulensis) was the best all round performer yielding the third highest volume production (4.2 m³ ha^?1 yr^?1) and ranking in the top quartile for forking, branching and straightness. Within variety camaldulensis a weak correlation was found between height and mean annual rainfall, provenances from lower rainfall areas being more likely to produce taller trees. A trend for smaller numbers of persistent branches with decreasing rainfall was observed for the species as a whole.     

NEW SOIL CONSERVATION ACT IN VICTORIA

The breeding programme at Traralgon aims to improve Eucalyptus regnans F. v. M. as a forest tree by increasing the rate of growth, improving wood quality, and increasing resistance to damage by fire. Improvement may be accomplished in three ways:—(1) provenance trials (to determine the best place to collect seed for afforestation in a given location), (2) selection of individual trees within the chosen provenance, and (3) hybrids with species with greater resistance to fire and the ability to grow on poor sites. The major part of the work has been the provenance trials which show continuous genetic variation with altitude on the south eastern side of Mount Erica, Victoria.

Seed for the trials was collected in October 1959 from 68 trees on Mount Erica. with an average of 10 trees at each of seven altitudes from 1200 feet to 3250 feet. Studies were made of capsule size, germination, cotyledon area, and growth of seedlings in the nursery. Sixty-four open pollinated progenies were planted in a cubic lattice design in the Strzelecki Ranges at 1650 feet, and some smaller trials were planted at other places. Field measurements at two years of age and again at three years confirmed the trend shown in the nursery that seedlings from higher altitudes grew more slowly. Leaf shape also varied with altitude but survival of seedlings did not. A study of the relation of nursery measurements to field measurements showed promise of a technique for culling the slowest growing progenies in the nursery without the need for field planting all the progenies.

An examination of growth rates of progenies from a given altitude showed that large dominant trees rarely produced the fastest growing seedlings, consequently trees selected for breeding should not be simply the largest individuals but rather the parents which give the best progeny in nursery and field trials.

Experiments were commenced on the value for forestry of hybrids of E. regnans and some observations were made on seed production.     

Frost tolerance of six seed orchards of Acacia mearnsii (black wattle) and the effect of developmental stage and tree size on frost hardiness

Frost damage is the most important abiotic risk in Acacia mearnsii (black wattle) plantations in South Africa. Current A. mearnsii planting stock cannot tolerate temperatures below ?4°C, and therefore there is an urgent need to develop frost-tolerant seed. This study investigated the frost hardiness of seedlots from six South African A. mearnsii seed orchards located at altitudes of 1120–1458 m asl and latitudes of 26.7–29.8°S that were established with cold-hardy Australian provenances and/or local landraces from cold sites. Frost damage was assessed in four field trials established on two different dates in 2015. Three sites experienced extensive frost events, with frequency and intensity varying among sites. Minimum temperatures ranged from ?6.4°C to ?7.7°C across sites. The seedlot from the coldest, highest altitude orchard showed superior frost hardiness to other seedlots from lower altitude and warmer orchards of similar genetic origin. Thus, site climatic characteristics are important for the development of cold hardiness in A. mearnsii seed orchards. Frost hardiness in young A. mearnsii trees was significantly related to age and tree size. At four months of age, trees were highly susceptible to frost damage irrespective of tree size and orchard origin (60–71% frosted trees). Frost hardiness increased with age and was very high at c. nine months across orchards (1–8% frosted trees at one site and 0–2% at another site). At nine months, although the extent of frost damage was low, this was inversely related to tree size. The percentage of trees that recovered from frost damage also increased with age of frost damage, this being 21% at the site frosted at four months of age and 65–67% at the sites frosted at nine months of age. Finally, there were no differences in tree growth at 14 months suggesting that, unlike cold hardiness, the differences in environment between the orchards did not affect the growth performance of the offspring.     

Are there genetic differences in susceptibility of Eucalyptus nitens and E. regnans stems to defect and decay?

Levels of spread of wood discolouration and incipient decay associated with artificial stem wounds were studied in a provenance trial of Eucalyptus regnans and a progeny trial of E. nitens. Natural incidence of discolouration and numbers and sizes of kino veins were also examined in a provenance × fertiliser interaction trial in E. regnans.

No differences were found between provenances of E. regnans for degree of spread of discolouration despite significant differences in tree diameter. However, incidence and size of kino veins differed between provenances of E. regnans. For E. nitens the spread of discolouration was less than that in E. regnans, and there were no significant differences in discolouration amongst the 10 open-pollinated families, or associated with tree diameter. Heritability estimates for lateral and longitudinal spread in E. nitens were relatively low and had large errors attached due to the small number of families sampled.

Degree of lateral spread was correlated with tree diameter in E. regnans but not in E. nitens. Nitrogen fertiliser did not appear to influence defect levels in E. regnans. However, adding phosphorus fertiliser was associated with fewer and smaller kino veins in disc samples removed from the base of the green crown.     

Provenance variation,genetic parameters and potential gains from selection for biomass and cineole production in three-year-old Eucalyptus loxophleba subsp. gratiae progeny trials

ABSTRACT

Ninety families from six provenances of Eucalyptus loxophleba subsp. gratiae were established near Brookton, Western Australia, and Condobolin, New South Wales, and 89 of these same families were established at Monarto, South Australia. All three trials were assessed at age three years for biomass productivity and the trial at Brookton was assessed for leaf cineole concentration. Provenance performance across the sites was most similar between Monarto and Condobolin, while the ranking of provenances was more divergent between those sites and Brookton. Presence or absence of unstable families may change provenance ranking. Additive variance was not significant for the Condobolin trial. Heritability of green biomass at age three years was ?² = 0.19 ± 0.06 and ?² = 0.16 ± 0.05 at Monarto and Brookton, respectively. The heritability of leaf cineole concentration at Brookton was ?² = 0.50 ± 0.08 and whole-tree cineole yield, ?² = 0.11 ± 0.04. The cross-site genetic correlation between Brookton and Monarto was r_g = 0.55 ± 0.20, suggesting the presence of some genotype × environment interaction. Removing the six most unstable families resulted in a cross-site genetic correlation of r_g = 0.97 ± 0.25. Estimated mean gains from selection scenarios treating Brookton and Monarto as representing two separate environments or as a single environment differed by about 5.0%. The exclusion of six unstable families reduced that difference to 1.4%. Selection on biomass alone may result in a slight increase in total cineole yield per tree but, in this experiment, it resulted in a reduction in mean leaf cineole concentration. Leaf cineole concentration used in conjunction with biomass may be a useful selection criterion in the absence of data for total mass of cineole produced per tree.     

MANAGEMENT OF WHITE STRINGYBARK FORESTS (EUCALYPTUS EUGENIOIDES) FOR PULPWOOD PRODUCTION

Following the poisoning of some species of tree and shrub seedlings in galvanized iron tubes used as substitutes for tinplate at the N.S.W. Forestry Department nurseries, a series of experiments was carried out at Cardiff, near Newcastle, and at Pennant Hills nursery, using Callitris cupressiformis seedlings.

None of the expected chlorosis was found in a range of tube types with various coatings and it was concluded that a concurrent change in Forestry Department procedure, involving the addition of lime, had been responsible for the disappearance of the trouble. Additional lime had further improved growth and even the addition of zinc corrosion product had not caused chlorosis.

Despite a slight superiority of top growth in galvanized iron over that in tinplate at Cardiff, it was found that a minor and almost certainly unimportant reduction in root growth existed in galvanized tubes at both locations.

It is concluded that galvanized tubes are suitable for all species, including those known to be sensitive to zinc, provided some lime is used in the tubing soil.     

Inoculation with Pure Cultures of Mycorrhizal Fungi of Radiata Pine Growing in Partially Sterilized Soil

Pinus radiata D.Don seedlings were successfully inoculated with Rhizopogon luteolus introduced in the mycelial stage into a nursery soil partially sterilized with methyl bromide at 3 lb, 5 lb and 7 lb per 100 cu ft or with aerated steam at 60°C, 71°C and 82°C. The sterilization treatments were also effective against damping-off and improved the growth of seedlings. Recolonization of soil by damping-off organisms was apparently slower after aerated steam sterilization than after methyl bromide. Short root production was reduced by methyl bromide applied at 7 lb per 100 cu ft, but was not affected by lower rates of application. Soil micro-organisms apparently detoxified methyl bromide. The effect of micro-organisms on the introduced fungus and the growth of seedlings is discussed.     

Growth and form of Eucalyptus nitens progenies in New South Wales,and selection strategies for a seedling seed orchard

Eucalyptus nitens is potentially the most important eucalypt species for plantations in the tablelands regions of New South Wales. However, genetic parameters and data for provenance and progeny performance of the species in this State have previously not been available. A test of 30 open-pollinated families was established near Tumbarumba (NSW) in 1989, and assessed for a number of growth and form traits at age 5 years. Victorian provenance material, including seedling seed orchard progenies, was generally superior to NSW seed sources for growth and form traits but more prone to forking; all provenances included some superior individual families. Estimates of individual heritability were low to moderate (0.14 to 0.44) for seven growth, stem and branch form traits, with low standard errors, and very low for occurrence of forks and ramicorn branches. Genetic correlations among commercially important growth and form traits were generally moderate to high, and favourable. Selection of trees in the test to retain in a theoretical seedling seed orchard, using a multi-trait selection index, resulted in retention of 90 trees over 11 families, with high gains in growth and form (13.2 to 20.7 percent). Alternative selection strategies, retaining 90 trees over 15 families, gave somewhat lower gains in most traits but a more even distribution of trees over the orchard area.     

Investigating optimal site conditions for flower bud production in Eucalyptus smithii orchards in South Africa

Eucalyptus smithii is an important commercial forestry species in South Africa. The species’ shy and erratic flowering tendencies hinder its genetic improvement and seed production. Breeders and seed producers are highly dependent on paclobutrazol (PBZ) applications for encouraging flower and seed production in E. smithii orchards. During the summer of 2003/04, an E. smithii flowering field trial series was established across a range of high elevation (1568–1828 m asl), cool temperate (13.8–15.5°C mean annual temperature (MAT)) commercial forestry sites in South Africa. The main objective was to investigate the interaction between PBZ and a range of climatic and landscape factors on E. smithii floral bud (umbel) production. The main aim was to define optimum environmental conditions for E. smithii umbel production and potential orchard establishment. In the fifth and sixth years after planting, 64% and 83% of the control (nil PBZ) grafted trees and 94% and 94% of PBZ-treated trees produced umbels. In the fifth year, PBZ application increased mean (across-site) umbel production per tree by 132%. Regardless of whether PBZ was applied or not, mean umbel production varied markedly across sites. In the absence of PBZ application, E. smithii test orchards located on south-west facing slopes in high elevation (>1550 m asl) areas at the lower end of the applied MAT range were generally the most productive on the basis of umbel crop. The study demonstrated that, through careful site selection, dependency on PBZ to achieve satisfactory umbel production in reproductively mature E. smithii trees may be substantially reduced. Within the elevation and MAT ranges applied in the trial series, E. smithii orchards situated in low positions in the landscape were at high risk of being severely damaged by frosts.     

Authors and fields of research

Growth and morphological differences between 12 provenances of Grevillea robusta (from New South Wales and Queensland, Australia) grown at two locations on the tropical Atherton Tablelands of northern Australia were investigated at age 40 months. The following measurements were taken: tree survival; height; diameter at breast height (DBH); number of branches and forks per tree; branch diameter and angle; crown diameter and tree form.

Significant differences between the provenances were found in most of the characteristics measured. Only DBH showed a site x provenance interaction. Two provenances (Duck Creek and Tyalgum) performed best. Provenance similarities in their morphological responses were examined using hierarchical cluster analysis.     

Interactions between herbivores,vegetation and eucalypt tree seedlings in a plantation forestry environment

Non-lethal management methods for reducing mammal browsing damage to Eucalyptus seedlings during plantation establishment are currently being investigated in Tasmania, Australia. One method is use of selective retention of non-seedling vegetation in plantations. To assess its potential, information is needed on how herbivores use such vegetation and whether it has positive or negative effects on browsing and growth of commercial tree seedlings. We quantified the populations of five mammalian herbivore species in and around a spot-herbicided E. nitens plantation during its establishment. We also investigated several aspects of the interactions between those mammalian herbivores, insect herbivores, tree seedlings and non-seedling vegetation. We found that overall population densities were high for red-bellied pademelons (Thylogale billardierii) and red-necked wallabies (Macropus rufogriseus rufogriseus), but very low for common brushtail possums (Trichosurus vulpecula), common wombats (Vombatus ursinus) and the introduced European rabbit (Oryctolagus cuniculus). Population densities of the five mammalian species did not change in response to planting E. nitens seedlings. Dominant vegetation in the plantation was grass, then forbs and non-grass monocots. Herbivores ate a large proportion of available plantation vegetation in unfenced plots. Mammal browsing had little effect on survival of E. nitens seedlings 15 weeks after planting, but significantly reduced their growth. In unfenced plots, insects, mainly Heteronyx spp., caused twice as much damage to seedlings as browsing mammals. The absence of mammalian browsing in fenced plots, which resulted in high grass cover, was associated with reduced insect damage to seedlings.     

1. Effects of air and soil temperature

Effects of air and soil temperatures on the regeneration of roots of P. radiata D. Don seedlings following a single root-pruning was examined under controlled conditions. Root regeneration is favoured by air temperatures in the range 20° to 30°C where soil temperature corresponds to ambient air temperature. When soil temperature is controlled independently of ambient air temperatures, low and high soil temperatures do not favour root growth irrespective of the air temperature. The most favourable temperatures for root growth are similar to those for growth of the seedling as a whole. Root morphology changes markedly with soil temperature, from thick, white, brittle roots at low temperatures to thin, flexible, suberized roots at higher temperatures. The implications of the results to some aspects of silvicultural practice are discussed.     

Some trial results with the weedicide Velpar in Pinus radiata plantations

The weedicide Velpar (active ingredient hexazinone) was found to control a variety of grasses and flatweeds in three trials at Kowen Forest, A.C.T., whereas recently planted Pinus radiata seedlings appeared relatively unaffected. In the trials Velpar was applied at three levels, before, immediately after, and 12 months after planting of the pine seedlings. Two other weedicides were used for comparison (Vorox AA and DPX 410). Good weed control was achieved and this was reflected in significant growth responses by Pinus radiata.     

Short-rotation coppice agroforestry for charcoal small business in Papua New Guinea

ABSTRACT

Fuelwood is an integral part of the Papua New Guinea domestic economy, with consumption estimated at 1.8 m³ person^–1 year^–1. Social stress in many districts is evident by high prices for and the conflict generated by competition for fuelwood. This paper describes three related activities designed to develop small businesses based on short-rotation coppice (SRC) agroforestry systems for fuelwood. These activities are: 1) a survey of domestic fuelwood consumers and vendors (n = 4110) in fuelwood-stressed districts in urban and rural areas of lowlands and highlands; 2) field trials of ten candidate SRC species, at two spacings, in 2–3 year rotations, with measurements of wood volume after two years, coppice vigour, burning characteristics, and market acceptance; and 3) facilitating the establishment of SRC-grown charcoal businesses. The survey found the fuelwood economy has a very short, direct supply chain in a completely informal environment. This paper summarises the fuelwood economy and illustrates the opportunity to create a new fuelwood supply chain that could deliver sustainably harvested and value-added fuelwood to consumers, especially in urban areas and the commercial sector. The SRC systems appealed to landholders because they could intercrop vegetables in the first year, and had the option of carrying over some trees to grow on to poles. The best SRC woodlot species were Eucalyptus grandis for the highlands and E. tereticornis for the lowlands. Calliandra calothrysus is also a suitable SRC species for alley systems in highland gardens. In the highlands, SRC firewood and charcoal production yield higher estimated returns to labour (43 and 24 PNG Kina person^–1 day^–1, equivalent to $US 20–11 person^–1 day^–1) compared with the main alternative crops of sweet potato and coffee (21 and 15 Kina person^–1 day^–1 respectively). As SRC-grown wood appears different from the normal, wild-collected wood for sale, there was resistance to it in the market. As a value-adding option, the establishment of charcoal producer groups was facilitated in Mt Hagen and Lae. The group business structures in the two centres were very different, reflecting their socio-cultural contexts. A flourishing SRC-based biomass energy sector will require a multi-sectoral national fuelwood policy.