https://ogma.newcastle.edu.au/vital/access/ /manager/Index ${session.getAttribute("locale")} 5 https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:26654 Den) of a 69-year-old Eucalyptus regnans forest comprising 251 plots with resolution of the order of 0.04 ha. Using the NCut method we predicted basal area (BA_Ha) per hectare and sapwood area (SA_Ha) per hectare, a well-established proxy for transpiration. Sapwood area was also indirectly estimated with allometric relationships dependent on LiDAR derived S_Den and BA_Ha using a computationally efficient procedure. The individual tree detection (ITD) rates for the LMF and NCut methods respectively had 72% and 68% of stems correctly identified, 25% and 20% of stems missed, and 2% and 12% of stems over-segmented. The significantly higher computational requirement of the NCut algorithm makes the LMF method more suitable for predicting S_Den across large forested areas. Using NCut derived ITD segments, observed versus predicted stand BA_Ha had R² ranging from 0.70 to 0.98 across six catchments, whereas a generalised parsimonious model applied to all sites used the portion of hits greater than 37 m in height (PH₃₇) to explain 68% of BA_Ha. For extrapolating one ha resolution SA_Ha estimates across large forested catchments, we found that directly relating SA_Ha to NCut derived LiDAR indices (R² = 0.56) was slightly more accurate but computationally more demanding than indirect estimates of SA_Ha using allometric relationships consisting of BA_Ha (R² = 0.50) or a sapwood perimeter index, defined as (BA_HaS_Den)^½ (R² = 0.48).]]> Wed 11 Apr 2018 16:13:53 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:22843 Eucalyptus regnans and E. delegatensis stands, correlated strongly with forest overstorey stocking density (R² 0.72). This curvilinear relationship was used with routine forest stocking density and basal area measurements to estimate sapwood area of the forest overstorey at various times in 15 research catchments in undisturbed and disturbed forests located in the Great Dividing Range, Victoria, Australia. Up to 45 years of annual precipitation and streamflow data available from the 15 catchments were used to examine relationships between mean annual loss (evapotranspiration estimated as mean annual precipitation minus mean annual streamflow), and sapwood area. Catchment mean sapwood area correlated strongly (R² 0.88) with catchment mean annual loss. Variation in sapwood area accounted for 68% more variation in mean annual streamflow than precipitation alone (R² 0.90 compared with R² 0.22). Changes in sapwood area accounted for 96% of the changes in mean annual loss observed after forest thinning or clear-cutting and regeneration. We conclude that forest inventory data can be used reliably to predict spatial and temporal variation in catchment annual losses and streamflow in response to natural and imposed disturbances in even-aged forests. Consequently, recent advances in mapping of sapwood area using airborne light detection and ranging will enable high resolution spatial and temporal mapping of mean annual loss and mean annual streamflow over large areas of forested catchment. This will be particularly beneficial in management of water resources from forested catchments subject to disturbance but lacking reliable long-term (years to decades) streamflow records.]]> Sat 24 Mar 2018 07:16:04 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:24569 1.3). Tree taper data were coupled with stump dimensions data in a mixed-effects model to predict each stump's BA at 1.3 m, and sapwood taper data from buttress logs were used to improve each stems ̂R_1.3. Using this procedure, we found our study site to have an ̂R_1.3 of 0.21 and total stand SA at 1.3 m height of 9.3 m² ha⁻¹. We quantified the bias in traditional ̂R_1.3 estimates that use cores to measure sapwood thickness and diameter tape to calculate SA. We show traditional methods underestimate inline image that increases with tree diameter and decreases with stem circularity, whereas our methodology gave more accurate measures of SA in large buttressing trees. Our methodology also provides a more efficient way of generating maps of SA variation across large forested catchments.]]> Sat 24 Mar 2018 07:11:30 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:24993 1.3) in a large number of trees to understand the spatial heterogeneity of tree and stand sapwood area within and between forest communities, and develop allometric relationships that predict SA_1.3 with forest inventory data. We also apply tree competition models to determine the degree to which the relationship between SA_1.3 and tree basal area at 1.3 m height (BA_1.3) is influenced by competition. Methods: We visited 25 recently harvested southeastern Australian forest sites consisting of 1379 trees and 5 Eucalyptus species to evaluate a new efficient data collection method for estimating SA_1.3 with tree taper and stump dimensions data using mixed effects models. The locations of 784 stumps within one 5-ha site were accurately mapped using an unmanned aerial vehicle (UAV), and four distance-dependent tree competition models were applied across the site to explain within-stand variation in the ratio of SA_1.3 to BA_1.3. Data from 24 additional sites, consisting of ten 15 m radial plots per site, were used to analyse within-site variation in R_Ha (the ratio of stand sapwood area SA_Ha to stand basal area BA_Ha). The radial plots were merged within each site to evaluate between-site variations in R_Ha across the landscape. For predicting SA_Ha with forest inventory data, we computed the relationship between SA_Ha and a new index of total stem perimeter per hectare, defined as √BA_HaN_T, where N_T is tree stocking density. Important Findings: Our 1379 measured stems represent the most comprehensive measure of sapwood area, surpassing the 757 measured stems in native eucalypt forests published in literature. The species-specific R_Ha varied considerably across sites and therefore extrapolating SA_Ha with spatially distributed BA_Ha maps and a generalized R_Ha would introduce local uncertainty. We found that the species-specific stem perimeter index was more effective at capturing variability in SA_Ha across the landscape using forest composition, structure and density data (R²: 0.72–0.77). The strong correlation between tree SA_1.3 and BA_1.3 improved slightly using tree competition models (R² increased from 0.86 to 0.88). Relating SA_Ha to routinely measured forest inventory attributes within permanent plots and Light Detection and Ranging (LiDAR) data may provide opportunities to map forest water use in time and space across large areas disturbed by wildfire and logging.]]> Sat 24 Mar 2018 07:09:55 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:42210 2 remote study area, a rainfall interpolation procedure using available rainfall data and information on terrain was integrated into a new seasonal streamflow model, called ABCF, which uses catchment sapwood area (SA) as the emergent property that equilibrates with potential evapotranspiration (PET), and a soil storage threshold that reduces AET below PET when soil water is limiting. We produce seasonal estimates of streamflow with Nash Sutcliffe efficiencies of 0.85, 0.87, and 0.91 for three major catchments within the study area. A fundamental feature of the "top-down" model approach is the use of LiDAR data and forest inventory data to model forest structural properties that relate strongly with SA. Building on our previous work with this modelling framework, our representation of eco-hydrological properties of the forest has been refined with a more accurate procedure for estimating stand mean sapwood thickness, and hence SA, and a remotely sensed tree stocking density (N) of old-growth forests to correct the temporal evolution of N as a means to improve SA estimates. Regional consistency of model parameters shows that the "top-down" modelling framework may be used to estimate streamflow in ungauged catchments using a forest growth model. The seasonal model generalised for both water-limited and water-unlimited forest conditions has significant potential for application in water supply planning and drought security.]]> Fri 26 Aug 2022 09:29:20 AEST ]]>