Browsing by Browse by SEO 2008 "820105 Softwood Plantations"

Accurate information on tree height distribution can provide a better understanding of forest productivity and biomass estimation. Airborne light detection and ranging remote sensing, also known as airborne laser scanning (ALS), has proven to be an effective tool for deriving tree height information in forests. While tree height has been reported to vary in response to many environmental factors, few researchers have demonstrated the effect of topography on tree height variation using ALS data. This study investigated the relationship between tree height variation and ALS-derived topographic aspect and slope factors within two even-aged radiata pine ('Pinus radiata' D. Don) plantation sites in Nundle, New South Wales, Australia. A total of 447 trees was sampled from 77 plots in two plantation age classes: 193 trees from a 34-year-old site and 254 trees from a 9-year-old site. ALS height estimates were highly correlated with field heights (R² = 0.90 and RMSE = 0.66 for 2002 and R² = 0.87 and RMSE = 1.49 for 1977 sites). ALS-derived slope and aspect metrics were shown to have a significant relationship with height variation across the stands. The slope (P<0.01) and aspect (P<0.001) were significant in the mixed linear models. Overall taller trees were found on slopes below 10° and on southerly aspects, while shorter trees dominated steeper slopes (>20°) and on northerly aspects. However, aspect gradient appeared to have more significant effect on tree heights than slope classes. These results were further verified using an additional 2,000 randomly located trees sampled across the plantations. The study demonstrates a significant relationship between tree height variation and ALS-derived ground aspect and slope categories which may have potential benefits for improving current wood resource inventories and future productivity models.

The aim of this study was to determine whether diameter at breast height (DBH, at 1.3 m) and total height of radiata pine ('Pinus radiata' D. Don) trees showed any significant relationships with microsite estimates of solar radiation. A total of 77 plots were established in two even-aged stands of radiata in Nundle State Forest, New South Wales, Australia. Within these plots, tree DBH and height measurements were recorded and their relationships with solar radiation evaluated. Airborne light detection and ranging (LiDAR) data were processed to generate a high resolution digital elevation model (DEM), and the DEM was used for calculating the incoming solar radiation. Overall, at both study sites, taller and larger trees were found on areas with lower solar radiation, possibly due to a lower loss in soil moisture. The findings of this study suggest that LiDAR-derived DEM estimates of solar radiation are significantly correlated with DBH and height variation, and therefore suitable for use as a sub-compartment stratification variable as well as for possible inclusion in fine-scale estimates of 'P. radiata' growth and productivity.

Context: Reliable information on tree stem diameter variation at local spatial scales and on the factors controlling it could potentially lead to improved biomass estimation over pine plantations. Aims: This study addressed the relationship between local topography and tree diameter at breast height (DBH) within two even-aged radiata pine plantation sites in New South Wales, Australia. Methods: A total of 85 plots were established, and 1,302 trees were sampled from the two sites. Airborne light detection and ranging (LiDAR) was used to derive slope and aspect and to link them to each individual tree. Results: The results showed a significant relationship between DBH and local topography factors. At both sites, trees on slopes below 20° and on southerly aspects displayed significantly larger DBHs than trees on steeper slopes and northerly aspects. Older trees with similar heights also exhibited a significant relationship between DBH and aspect factor, where greater DBHs were found on southerly aspects. Conclusions: The observed correlation between tree DBH and LiDAR-derived slope and aspect could contribute to the development of improved biomass estimation approaches in pine plantations. These topographical variables are easily attained with airborne LiDAR, and they could potentially improve DBH predictions in resource inventories (e.g. stand volume or biomass) and support field sampling design.

TREEPLAN is an advanced analytical tool providing accurate and precise predictions of genetic values to operational tree breeders. This project aimed to exploit TREEPLAN's analytical power for the benefit of all sections of the forest growing industry; in particular, the deployment sector and programs not traditionally associated with the Southern Tree Breeding Association. The outputs include: the routine inclusion of reproductive and fitness traits into the assessment framework; better prediction of stand performance through competition models; the undertaking of pilot studies using data from large industry programs; and the better modelling of the genetic structures of hybrid populations.

Efforts to support farmers living near forests to achieve sustainable agriculture and natural resource conservation have predominantly focused on services or schemes such as agricultural extension and community-based forest management, with little attention being focused on farmers' local soil knowledge (LSK). This paper provides insights into farmers' LSK, their agricultural and soil conservation practices and economic reliance on natural forests. Household survey (n = 146) and key informant interviews (n = 24) with farmers was conducted in two communes of the buffer zone of Bach Ma National Park, Central Vietnam. The results indicated that 70% of farmers had reasonable LSK, and farmers with comprehensive LSK (21%) were more familiar with their soils and the relationships between essential soil properties that reflect soil problems. Most farmers used soil colour to allocate crop types because of its association with soil fertility or plant yields. Erosion was identified as a major production constraint, yet less than a fifth of farmers had placed soil erosion control measures into practice. However, low-cost techniques, such as growing native plant cover (e.g.“lồ ô” (Bambusa balcooa)), were suggested by a few farmers to address soil loss. The Katu farmers had greater potential to secure LSK as the next generation are continuing to farm, while the Kinh farmers' LSK is threatened by a lack of engagement in farming by the younger generation. However, Katu farmers have less opportunity to use their LSK due to limitations in farm size and cropping options. These findings have raised different challenges to the succession of farmers' LSK for sustainable agriculture and natural resources conservation in the two communes. Finally, this study highlighted the importance of involving farmers' LSK in the early stages of designing and conducting research through forums or workshops to improve relevance and adoption of practices developed so they align with local people's understanding and practice.

'Pinus radiata' (GF27- and Guadalupe-based intraspecific hybrids) and 'Pinus pinaster' were trialled to examine the potential for commercial deployment on three lower-rainfall sites within the 500-800 mm rainfall zone of New South Wales. All three ex-pasture sites were considered to be dry for 'P. radiata'; two lower-elevation sites to the west of Gundagai being more challenging than a high-elevation site near Bombala. Cuttings and seedlings of genetically improved 'P. pinaster' and 'P. radiata' and a Guadalupe x routine cross seedlot of 'P. radiata' were planted at three stockings (625, 1250 and 1850 stems per hectare (sph)) and were assessed for survival, growth (diameter at breast height, height, volume), form (straightness, malformations, branch size, branch angle) and number of commercially acceptable trees per hectare up to age 8 years.

Reducing the impact of the siricid wasp, Sirex noctilio is crucial for the future productivity and sustainability of commercial pine resources in South Africa. In this study we present an alternative modeling framework that accurately identifies existing commercial pine forests that are susceptible to S.noctilio infestation. Using maps that show the potential distribution of S.noctilio infestations, forest managers can now adopt the most appropriate course of intervention before the wasp population reaches epidemic proportions. Two machine learning methods were used to predict the potential geographical distribution of S.noctilio infestations and to examine the relationship between the siricid and its environment. More specifically, classification trees (CT) and the random forest classifier (RF) were used to examine the relationship between 1301 pine forest compartments (showing the absence or presence of S.noctilio) and 72 environmental variables (consisting of historical climatic and topographic datasets). The results obtained from this study are very encouraging and show that RF was the most accurate predictive model and had several advantages over CT. The overall model accuracy (kappa statistic) was 0.71 for CT whereas RF produced accuracies of 0.77. Additionally, accuracy assessments by an independent dataset might be unnecessary as RF provides a reliable internal estimate of accuracy as determine by the out of bag error estimate. The highest ranked environmental variables as determined by RF were the median rainfall for February followed by the evapotranspiration during August and September. The results concur with previous studies and indicate that pine forests that are experiencing some form of stress are more susceptible to S.noctilio attack. The RF prediction model when used in conjunction with geographical information systems provides a useful and robust tool that can assist with current forest pest management initiatives.

Mixed species plantations have the potential to exceed the biomass production of monocultures. This study examined the productivity of three mixed species plantations in southeastern Australia. Two of these trials contained a 'Eucalyptus' sp. ('E. saligna' Smith or 'E. nitens' [Deane & Maiden] Maiden) planted with 'Acacia mearnsii' De Wild., and the other contained 'Pinus radiata' D. Don with 'A. mearnsii', 'A. decurrens' Willd., 'E. benthamii' Maiden & Cambage, or 'E. smithii' R. Baker. Each trial contained both monocultures and mixtures, and was replicated three or four times. Tree diameters or heights were smaller in mixture than monocultures for some species (P. radiata diameters of 5.9 cm and 7.0 cm in 2:1 mixtures with 'A. mearnsii' and monocultures, respectively) but tended to increase (not significantly) for other species ('E. nitens' diameters of 10.6 cm and 8.5 cm and 'A. mearnsii' diameters of 9.2 cm and 8.8 cm in 1:1 mixtures and monocultures, respectively). As a result, mixtures were intermediate in aboveground biomass production between monocultures of the mixed species in each trial, or they were not significantly different from the monocultures. Competition for resources other than nitrogen (N), such as light, soil moisture, or other nutrients, appeared to balance any positive effects that might have occurred, such as through increased N availability. For example, foliar N concentrations of 'E. saligna' were higher in mixture (23.1 mg g⁻¹) than monoculture (17.7 mg g⁻¹); however, this did not result in greater aboveground tree biomass. The range of different growth responses from mixing different species in this study and in other studies shows that a fundamental understanding of the underlying processes is required to enable a greater predictive capacity of the circumstances under which mixtures can be successful.

Computer simulation is the only realistic method of evaluating alternative methods of breeding hybrid forest trees. Empirical tests would be very long term and expensive. This paper describes the development of a simulation program, called XSIM, which generates two different but closely related outcrossing tree species. The genetic correlation between performance in each parental species and performance in the resulting hybrid can be set, in addition to the amounts and types of variances in each parental species. The breeding strategies available for testing include conventional reciprocal recurrent selection, reciprocal recurrent selection with forward selection, recurrent selection within each pure species, and the creation of a synthetic species. XSIM allows the strategies to be compared using the same base populations, equivalent selection intensities, and comparable mating patterns. Innovative best linear unbiased prediction procedures allow all ancestral and current progeny generation data, from both parental species and the hybrid, to be analysed together. The theoretical basis for the simulation is given, and genetic and statistical models are described. In summary, XSIM allows rigorous comparisons of the strategies in terms of genetic gain per time and provides useful insight into hybrid forest tree breeding.

Insitu hyperspectral remote sensing was used to identify optimal spectral bands capable of discriminating pine trees that were attacked by the wood boring pest, 'Sirex noctilio'. The pest attacks all commercial pine species in South Africa and the symptoms on infected trees can be represented on a severity scale, as the green, red and grey stages of attack The objective of this study was to determine whether there is a significant difference between the mean reflectance (%) at each measured spectral bands (from 400 –1300 nm) for the green, red and grey stages of attack. Next, for the bands that were significantly different (P<0.001) in this spectral region, we sought to test whether some bands had more discriminating power than others by using the Jeffries - Matusita distance analysis technique. Using a field spectrometer, ninety reflectance measurements were obtained from several infected Pinus patula trees in Kwazulu-Natal, South Africa. Results indicate that spectral bands located in the visible portion (350 – 700 nm) and some spectral bands in the red edge (670-737 nm) of the electromagnetic spectrum could spectrally discriminate the different levels of S. noctilio attack. Although no single band is capable of total separability, results of the Jeffries Matusita (J-M) analysis indicate that an acceptable separability of 99.22% (J-M value of 1403) for all attack classes was reached when using a four band combination comprising of bands located at 500 nm, 521 nm, 685 nm, and 760 nm. The results encourage canopy scale detection and mapping of S.noctilio attack in pine forest plantations using airborne or spaceborne hyperspectral sensors