Species-Specific Allometric Equations for Predicting Belowground Root Biomass in Plantations: Case Study of Spotted Gums (Corymbia citriodora subspecies variegata) in Queensland

Spotted gum (Corymbia citriodora spp. variegata; CCV) has been widely planted, has a wide natural distribution, and is the most important commercially harvested hardwood species in Queensland, Australia. It has a great capacity to sequester carbon, thus reducing the impact of CO2 emissions on climate. Belowground root biomass (BGB) plays an important role as a carbon sink in terrestrial ecosystems. To explore the potential of biomass and carbon accumulation belowground, we developed and validated models for CCV plantations in Queensland. The roots of twenty-three individual trees (size range 11.8–42.0 cm diameter at breast height) from three sites were excavated to a 1-m depth and were weighed to obtain BGB. Weighted nonlinear regression models were most reliable for estimating BGB. To evaluate the candidate models, the data set was cross-validated with 70% of the data used for training and 30% of the data used for testing. The cross-validation process was repeated 23 times and the validation of the models were averaged over 23 iterations. The best model for predicting spotted gum BGB was based on a single parameter, with the diameter at breast height (D) as an independent variable. The best equation BGB = 0.02933 × D2.5805 had an adjusted R2 of 0.854 and a mean absolute percentage error of 0.090%. This equation was tested against published BGB equations; the findings from this are discussed. Our equation is recommended to allow improved estimates of BGB for this species.

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Sensitivity of global gross primary production to elevated CO2

10.5194/egusphere-egu21-1744 ◽

2021 ◽

Author(s):

Wenjia Cai ◽

Iain Colin Prentice

Keyword(s):

Field Experiments ◽

Carbon Sink ◽

Gross Primary Production ◽

Light Response ◽

Terrestrial Ecosystems ◽

Percentage Increase ◽

Terrestrial Plants ◽

Fertilization Effect ◽

Vegetation Models ◽

The Impact

Terrestrial ecosystems have accounted for more than half of the global carbon sink during the past decades and offset 25%-30% of current anthropogenic CO2 emissions. The projected increase in CO2 concentration will depend on the magnitude of terrestrial plants&#8217; feedback to CO2: i.e. the sensitivity of plant carbon uptake in response to elevated CO2, and the strength of the CO2 fertilization effect (CFE) in a changing (and warming) environment. Projecting vegetation responses to future increases in CO2 concentration under climate change is a major uncertainty, as ecosystem models, field experiments and satellite-based models show large disagreements. In this study, using a recently developed, parameter-sparse model (the &#8216;P model&#8217;), we assess the sensitivity of GPP to increasing CO2 under idealized conditions, in comparison with other vegetation models and field experiments. We investigate the impact of two central parameters, the ratio of Jmax to Vcmax (at a common temperature) and the curvature of the light response curve, on the sensitivity of GPP to CO2. We also quantified the spatial-temporal trend of CFE using the &#946; factor, defined as the percentage increase in GPP in response to a 100-ppm increase in atmospheric CO2 concentration over a defined period. We show how modelled &#946; has changed over the satellite era, and infer the possible effect of climatic variables on changes of CFE from spatial patterns of the modelled trend in &#946;.

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Modelling past, present and future peatland carbon accumulation across the pan-Arctic region

Biogeosciences ◽

10.5194/bg-14-4023-2017 ◽

2017 ◽

Vol 14 (18) ◽

pp. 4023-4044 ◽

Cited By ~ 21

Author(s):

Nitin Chaudhary ◽

Paul A. Miller ◽

Benjamin Smith

Keyword(s):

Carbon Sink ◽

Accumulation Rate ◽

Arctic Region ◽

Terrestrial Ecosystems ◽

Cold Climate ◽

Carbon Accumulation ◽

Accumulation Rates ◽

Eastern Canada ◽

The Holocene

Abstract. Most northern peatlands developed during the Holocene, sequestering large amounts of carbon in terrestrial ecosystems. However, recent syntheses have highlighted the gaps in our understanding of peatland carbon accumulation. Assessments of the long-term carbon accumulation rate and possible warming-driven changes in these accumulation rates can therefore benefit from process-based modelling studies. We employed an individual-based dynamic global ecosystem model with dynamic peatland and permafrost functionalities and patch-based vegetation dynamics to quantify long-term carbon accumulation rates and to assess the effects of historical and projected climate change on peatland carbon balances across the pan-Arctic region. Our results are broadly consistent with published regional and global carbon accumulation estimates. A majority of modelled peatland sites in Scandinavia, Europe, Russia and central and eastern Canada change from carbon sinks through the Holocene to potential carbon sources in the coming century. In contrast, the carbon sink capacity of modelled sites in Siberia, far eastern Russia, Alaska and western and northern Canada was predicted to increase in the coming century. The greatest changes were evident in eastern Siberia, north-western Canada and in Alaska, where peat production hampered by permafrost and low productivity due the cold climate in these regions in the past was simulated to increase greatly due to warming, a wetter climate and higher CO2 levels by the year 2100. In contrast, our model predicts that sites that are expected to experience reduced precipitation rates and are currently permafrost free will lose more carbon in the future.

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Moisture and heat advection as drivers of global ecosystem productivity

10.5194/egusphere-egu2020-11870 ◽

2020 ◽

Author(s):

Dominik L. Schumacher ◽

Jessica Keune ◽

Diego G. Miralles

Keyword(s):

Primary Production ◽

Interannual Variability ◽

Carbon Sink ◽

Gross Primary Production ◽

Terrestrial Ecosystems ◽

Ecosystem Productivity ◽

Climate Conditions ◽

Source Regions ◽

Heat And Moisture ◽

The Impact

Terrestrial ecosystems play a key role in climate by dampening the increasing atmospheric CO2 concentrations primarily caused by anthropogenic fossil fuel emissions. The capability of the land biosphere to act as a carbon sink largely depends on climate conditions, which determine the energy and water availability required by plants to grow. Even though only a small part of the global land area is covered by vegetation, the impact of extreme dry and wet seasons has been shown to largely drive the global interannual variability of gross primary production. The climate in a certain area can be seen as the balance of different heat and moisture fluxes: local surface&#8211;atmosphere fluxes from below, entrainment of heat and moisture from aloft, and &#8216;horizontal&#8217; advection of heat and moisture from upwind regions. The latter provides a mechanism for remote regions to impact gross primary production downwind, and has received less scientific attention. Here, advection is inferred from a bird&#8217;s eye perspective, focussing on the five ecoregions with the largest interannual variability in peak productivity around the globe. Employing the atmospheric Lagrangian trajectory model FLEXPART, driven by ERA-Interim reanalysis data, we track the air residing over ecoregions back in time to deduce the origins of heat and moisture that affect ecosystem gross primary production. Utilizing the evaporative source regions supplying water for precipitation to these ecosystems, as well as the analogous source regions of advected heat, we estimate the contribution of advection to gross primary production. Our findings show that source regions of heat and moisture are not congruent: upwind land surfaces typically supply most of the advected heat, whereas upwind oceans tend to provide more moisture. Moreover, low gross primary production in heat-stressed and water-limited ecosystems is often accompanied by enhanced heat and reduced moisture advection from land regions, exacerbated by upwind land&#8211;atmosphere feedbacks. These results demonstrate that anomalies in atmospheric advection can cause ecosystem productivity extremes. Particularly in light of ongoing climate change, we emphasize the potentially detrimental effects of upwind areas that may cause long-lasting impacts on the terrestrial carbon budget, thereby further affecting the climate.

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The Influence of Cross-Section Thickness on Diameter at Breast Height Estimation from Point Cloud

ISPRS International Journal of Geo-Information ◽

10.3390/ijgi9090495 ◽

2020 ◽

Vol 9 (9) ◽

pp. 495

Author(s):

Milan Koreň ◽

Milan Hunčaga ◽

Juliana Chudá ◽

Martin Mokroš ◽

Peter Surový

Keyword(s):

Cross Section ◽

Cross Sections ◽

Point Cloud ◽

Point Clouds ◽

Estimation Accuracy ◽

Circle Fitting ◽

Section Thickness ◽

Diameter At Breast Height ◽

Breast Height ◽

The Impact

Circle-fitting methods are commonly used to estimate diameter at breast height (DBH) of trees from horizontal cross-section of point clouds. In this paper, we addressed the problem of cross-section thickness optimization regarding DBH estimation bias and accuracy. DBH of 121 European beeches (Fagus sylvatica L.) and 43 Sessile oaks (Quercus petraea (Matt.) Liebl.) was estimated from cross-sections with thicknesses ranging from 1 to 100 cm. The impact of cross-section thickness on the bias, standard error, and accuracy of DBH estimation was statistically significant. However, the biases, standard errors, and accuracies of DBH estimation were not significantly different among 1–10-cm cross-sections, except for oak DBH estimation accuracy from an 8-cm cross-section. DBH estimations from 10–100-cm cross-sections were considerably different. These results provide insight to the influence of cross-section thickness on DBH estimation by circle-fitting methods, which is beneficial for point cloud data acquisition planning and processing. The optimal setting of cross-section thickness facilitates point cloud processing and DBH estimation by circle-fitting algorithms.

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Ecological restoration and rising CO2 enhance carbon sink, counteracting climate change in northeastern China

Environmental Research Letters ◽

10.1088/1748-9326/ac3871 ◽

2021 ◽

Author(s):

Binbin Huang ◽

Fei Lu ◽

Xiaoke Wang ◽

Xing Wu ◽

Lu Zhang ◽

...

Keyword(s):

Climate Change ◽

Ecological Restoration ◽

Carbon Sink ◽

Remote Sensing Data ◽

Terrestrial Ecosystems ◽

Source Control ◽

Impact Of Climate Change ◽

The Individual ◽

Business As Usual ◽

The Impact

Abstract The impact of climate change, rising CO2, land use/land cover change (LC) and land management (LM) on carbon cycle in terrestrial ecosystems has been widely reported. However, rare studies have been conducted to clarify the impact of climate change and rising CO2 on carbon sink contributed by ecological restoration projects (ERPs). To better understand the impact of climate change and rising CO2 on ERPs, we took the Beijing-Tianjin Sand Source Control Project (BTSSCP) zone as an example to set different scenarios to distinguish the confounding effects of these factors on regional carbon budget based on remote sensing data-driven model. Compared with business as usual (BAU), our results showed climate change caused carbon loss of 78.97 Tg. On the contrary, ERPs contributed approximately 199.88 Tg C sink in forest and grassland. Furthermore, rising CO2 also contributed an additional 107.80 Tg C sink. This study distinguished the individual effects of different factors, and clarified the net carbon sink contributed by ERPs and rising CO2 and their significance to enhance regional carbon sink and reverse adverse effects of climate change on carbon sink. Furthermore, ERPs can sequester carbon dioxide faster and more effectively compared with rising CO2.

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Estimating large-root biomass from stump and breast-height diameters for Douglas-fir in western Oregon

Canadian Journal of Forest Research ◽

10.1139/x26-027 ◽

1996 ◽

Vol 26 (2) ◽

pp. 237-243 ◽

Cited By ~ 20

Author(s):

Walter G. Thies ◽

Patrick G. Cunningham

Keyword(s):

Pacific Northwest ◽

Root Biomass ◽

Dry Weight ◽

Belowground Biomass ◽

Douglas Fir ◽

Large Root ◽

Diameter At Breast Height ◽

Breast Height ◽

The Pacific ◽

Using Data

Estimates of belowground biomass are fundamental to understanding carbon cycling and sequestration and the dynamics of ecological systems and in designing studies of those systems. An important belowground component of stands in the Pacific Northwest is the large-root biomass associated with mature, second-growth, Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco). Sample Douglas-fir from four western Oregon stands were felled, and their stumps and root systems were excavated and cleaned. Biomass of all roots larger than 10 mm in diameter plus the belowground portion of the stump was determined on a dry-weight basis. Each tree was measured for stump diameter, 15 cm above the soil line, and for diameter at breast height. Regression models were constructed by using data from 82 trees from four stands. Stump diameters ranged from 24.1 to 92.5 cm, diameter at breast height ranged from 21.3 to 54.6 cm, and biomass ranged from 20.5 to 614.4 kg.

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Performance Analysis of Log Extraction by a Small Shovel Operation in Steep Forests of South Korea

Forests ◽

10.3390/f10070585 ◽

2019 ◽

Vol 10 (7) ◽

pp. 585 ◽

Cited By ~ 4

Author(s):

Eunjai Lee ◽

Sang-Kyun Han ◽

Sangjun Im

Keyword(s):

South Korea ◽

Predictive Ability ◽

Stand Density ◽

Production Costs ◽

Mixed Stands ◽

Forest Road ◽

Stem Size ◽

Diameter At Breast Height ◽

Breast Height ◽

The Impact

In South Korea, logs for low-value products, such as pulpwood and fuelwood, are primarily extracted from harvest sites and transported to roadside or landing areas using small shovels. Previous studies on log extraction, however, have focused on cable yarding operations with the goal of improving productivity on steep slopes and inaccessible sites, leaving small-shovel operations relatively unexamined. Therefore, the main objectives were to determine small-shovel extraction productivity and costs and to evaluate the impact of related variables on productivity. In addition, we developed a model to estimate productivity under various site conditions. The study took place in 30 case study areas; each area has trees with stems at a diameter at breast height ranging from 18 to 32 cm and a steep slope (greater than 15%). The areas ranged from 241 to 1129 trees per hectare, with conifer, deciduous, and mixed stands. Small-shovel drives ranged from 36 to 72 m per extraction cycle from stump to landing. The results indicated that the mean extraction productivity of small-shovel operations ranged between 2.44 to 9.85 m3 per scheduled machine hour (including all delays). At the forest level, the estimated average stump-to-forest road log production costs were US $4.37 to 17.66/m3. Small-shovel productivity was significantly correlated with stem size (diameter at breast height and tree volume) and total travelled distance (TTD). However, a Pearson’s correlation analysis indicated that stand density and slope did not have a significant effect on productivity. Our findings provide insights into how stem size and TTD influence small shovel performance and the predictive ability of productivity. Further, this information may be a valuable asset to forest planners and managers.

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Biomass retention and carbon stocks in integrated vegetation bands: a case study of mixed-age brigalow-eucalypt woodland in southern Queensland, Australia

The Rangeland Journal ◽

10.1071/rj14023 ◽

2015 ◽

Vol 37 (3) ◽

pp. 261 ◽

Cited By ~ 4

Author(s):

Justin G. Ryan ◽

Christine T. Fyfe ◽

Clive A. McAlpine

Keyword(s):

Aboveground Biomass ◽

Production Systems ◽

Soil Protection ◽

Grazing Land ◽

Diameter At Breast Height ◽

Breast Height ◽

Large Trees ◽

Eucalypt Woodland ◽

Pasture Area ◽

The Impact

Regrowth of native woody vegetation has the potential to provide an economically valuable source of carbon storage and other ecosystem services. There is a lack of readily applicable examples of how regrowth of forests and woodlands can be integrated with existing grazing production systems and provide soil-protection and water-retention benefits. A system of integrated vegetation bands (IVB) was applied to patchy regrowth of acacia and eucalypt vegetation in a grazed landscape of southern Queensland, Australia. Across a 39.8-ha catchment with 3–5% slope, regrowth of scattered native vegetation (18.4 ha) was surveyed and diameter at breast height and height for all woody plants were recorded. The IVB (6.3 ha) were then marked out as 25-m-wide bands set 100 m apart and offset at ~2–3% gradient to the contour line, retaining the densest/largest regrowth where possible. The data on diameter at breast height and height were analysed using allometric equations to compare aboveground biomass in the original regrowth condition (‘Original’) to that retained in the installed IVB (‘IVB-Riparian’). Estimates of aboveground biomass were calculated for the Original and IVB-Riparian and compared with three other potential regrowth-vegetation management ‘treatments’ in a desktop-modelling study. The models were designated as: (1) ‘Original’; (2) ‘Broad’ (broad-scale cleared with only a few large trees along a creek retained)’; (3) ‘Big Trees’ (only large trees >40 cm diameter at breast height retained); (4) ‘Riparian-IVB (bands of vegetation); and (5) ‘Riparian-IVB-Big Trees’ (large trees together with ‘IVB-Riparian’). In the non-forested area of the catchment, ‘Riparian-IVB-Big Trees’ (301 t), ‘Big Trees’ (249 t) and ‘Riparian-IVB’ (200 t) had the highest aboveground biomass retained, whereas ‘Broad’ resulted in the most pasture area (~33 ha) followed by ‘Riparian-IVB’ (~26 ha). The ‘Riparian-IVB’ treatment had the highest tree density within the vegetation bands and more than half (53%) of the original woody biomass in regrowth was retained on just under a quarter (23%) of the land area minimising the impact on the area of pasture/grazing land. This subsequently resulted in the ‘Riparian-IVB’ treatment having the highest carbon offset value (A$605 ha–1). The results demonstrate that the retention of native regrowth vegetation in either IVB or as large paddock trees can retain a large amount of aboveground biomass, with IVB having greater returns per hectare.

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Canadian national biomass equations: new parameter estimates that include British Columbia data

Canadian Journal of Forest Research ◽

10.1139/x07-224 ◽

2008 ◽

Vol 38 (5) ◽

pp. 1123-1132 ◽

Cited By ~ 86

Author(s):

Chhun-Huor Ung ◽

Pierre Bernier ◽

Xiao-Jing Guo

Keyword(s):

British Columbia ◽

Stem Bark ◽

Allometric Equations ◽

Parameter Estimates ◽

Data Set ◽

Stem Wood ◽

Diameter At Breast Height ◽

Breast Height ◽

Mass Estimate ◽

Species Specific

National allometric equations covering the most common tree species of Canada’s forests were produced based on tree mass data acquired in the early 1980s during the ENergy from the FORest (ENFOR) program. The equations allow us to calculate the mass estimate of four tree components (foliage, branches, stem bark, and stem wood) using either diameter at breast height or a combination of diameter at breast height and height. Missing from that data set, however, were the data from British Columbia. A usable British Columbia data set was finally found and has now been incorporated into the national data set. Here, we present revised allometric equations for six species covered in the previous work and also found in the British Columbia data set as well as for the “hardwoods”, “softwoods”, and “all species” equations. New equations are also provided for eight species specific to the British Columbia data.

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Modelling past, present and future peatland carbon accumulation across the pan-Arctic

10.5194/bg-2017-34 ◽

2017 ◽

Author(s):

Nitin Chaudhary ◽

Paul A. Miller ◽

Benjamin Smith

Keyword(s):

Carbon Sink ◽

Accumulation Rate ◽

Far East ◽

Terrestrial Ecosystems ◽

Cold Climate ◽

Carbon Accumulation ◽

Accumulation Rates ◽

Eastern Canada ◽

The Holocene

Abstract. Most northern peatlands developed during the Holocene, sequestering large amounts of carbon in terrestrial ecosystems. However, recent syntheses have highlighted the gaps in our understanding of peatland carbon accumulation. Assessments of the long-term carbon accumulation rate and possible warming driven changes in these accumulation rates can therefore benefit from process-based modelling studies. We employed an individual- and patch-based dynamic global ecosystem model with dynamic peatland and permafrost functionality and vegetation dynamics to quantify long-term carbon accumulation rates and to assess the effects of historical and projected climate change on peatland carbon balances across the pan-Arctic. Our results are broadly consistent with published regional and global carbon accumulation estimates. A majority of modelled peatland sites in Scandinavia, Europe, Russia and Central and eastern Canada change from carbon sinks through the Holocene to potential carbon sources in the coming century. In contrast, the carbon sink capacity of modelled sites in Siberia, Far East Russia, Alaska and western and northern Canada was predicted to increase in the coming century. The greatest changes were evident in eastern Siberia, northwest Canada and in Alaska, where peat production, from being hampered by permafrost and low productivity due the cold climate in these regions in the past, was simulated to increase greatly due to warming, wetter climate and greater CO2 levels by the year 2100. In contrast, our model predicts that sites that are expected to experience reduced precipitation rates and are currently permafrost free will lose more carbon in the future.

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