Carbon-dioxide-driven increase in foliage projective cover is not the same as increased woody plant density: lessons from an Australian tropical savanna
Gabriel M. Crowley
A * and Stephen A. Murphy A B
+ Author Affiliations
- Author Affiliations
A Artemis Nature Fund Inc., Malanda, Qld 4885, Australia.
B Research and Recovery of Endangered Species Group, School of Environmental and Earth Sciences, University of Queensland, Saint Lucia, Qld 4072, Australia.
* Correspondence to: gabriel.m.crowley@gmail.com
The Rangeland Journal 45(2) 81-95 https://doi.org/10.1071/RJ23001
Submitted: 3 January 2023 Accepted: 22 May 2023 Published: 15 June 2023
© 2023 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of the Australian Rangeland Society. This is an open access article distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND)
Abstract
Carbon accounting in tropical savannas relies on a good understanding of the effects of atmospheric carbon dioxide (CO2) and land management on foliage projective cover (FPC) and vegetation structure. We used generalised additive modelling to track changes in Autumn Persistent Green (APG, a satellite-image-derived measure of FPC) in six vegetation types on Cape York Peninsula, Australia, over an 18-year period, and examined the influence of fire and grazing land tenure. We then used field monitoring and variography (analysis of spatial autocorrelation) in a smaller study area to determine whether changes in APG reflected vegetation structural change. APG increased through the 18-year study period and was significantly influenced by vegetation type, recent fire history and grazing land tenure. Residual year-on-year increases suggest CO2 fertilisation was the main driver of APG increase. APG was reduced by fires in the previous year, with early dry season fires having greater impact than late dry season fires, particularly in grassland and rainforest. This is consistent with leaves being most fire sensitive early in the year, when they are actively growing, than in the late dry season, when they are dormant. As seedlings and suckers would be particularly fire-sensitive, early fires may therefore be more effective than late fires at preventing woody encroachment. We demonstrated that variography provides a good indication of whether APG increases are caused by increases in FPC alone, or by an increase in tree density. We found support for increased woody plant density in grasslands, and that this increase was most pronounced on grazing lands. Conversely, we found no support for stem density increases in the dominant eucalypt woodland, despite APG increases being highest in this vegetation type. Hence, increases in FPC cannot always be equated to increases in woody biomass, and may occur in their absence. This conclusion has serious implications for global carbon accounting.
Keywords: biophysical models, climate change and high CO2, fire vegetation patterns, grasslands, grazing pressure, remote sensing, savanna woodlands, vegetation structure.
References
Accad A, Kelley JAR, Richter D, Neldner VJ, Li J (2021) ‘Remnant regional ecosystem vegetation in Queensland, analysis 1997-2019.’ (Queensland Department of Environment and Science: Brisbane) Available at https://www.qld.gov.au/environment/plants-animals/plants/ecosystems/remnant-vegetation [accessed 14 April 2023]Anderegg, WRL, Kane, JM, and Anderegg, LDL (2013). Consequences of widespread tree mortality triggered by drought and temperature stress. Nature Climate Change 3, 30–36.
| Consequences of widespread tree mortality triggered by drought and temperature stress.Crossref | GoogleScholarGoogle Scholar |
Archer, S (1995). Herbivore mediation of grass-woody plant interactions. Tropical Grasslands 29, 218–235.
Archer SR, Andersen EM, Predick KI, Schwinning S, Steidl RJ, Woods SR (2017) Woody plant encroachment: causes and consequences. In ‘Rangeland systems: processes, management and challenges’. (Ed. DD Briske) pp. 25–84. (Springer International Publishing: Cham, Switzerland)
Ash, AJ, and Corfield, JP (1998). Influence of pasture condition on plant selection patterns by cattle: its implications for vegetation change in a monsoon tallgrass rangeland. Tropical Grasslands 32, 178–187.
Beringer, J, Hutley, LB, Tapper, NJ, and Cernusak, LA (2007). Savanna fires and their impact on net ecosystem productivity in North Australia. Global Change Biology 13, 990–1004.
| Savanna fires and their impact on net ecosystem productivity in North Australia.Crossref | GoogleScholarGoogle Scholar |
Biggs AJW, Philip SR (1995) Soils of Cape York Peninsula. Land Resources Bulletin QV95001. (Department of Primary Industries: Mareeba) Available at https://www.publications.qld.gov.au/dataset/f8fbc5f1-3fa7-4849-b04d-3ab581c5d03d/resource/e90e1bcf-477a-4f22-96e2-f6d90f3a4163/download/cypqv95001soilsofcapeyorkpeninsula.pdf [accessed 14 April 2023]
Bond, WJ, and Midgley, GF (2000). A proposed CO2-controlled mechanism of woody plant invasion in grasslands and savannas. Global Change Biology 6, 865–869.
| A proposed CO2-controlled mechanism of woody plant invasion in grasslands and savannas.Crossref | GoogleScholarGoogle Scholar |
Bond, WJ, and Midgley, GF (2012). Carbon dioxide and the uneasy interactions of trees and savannah grasses. Philosophical Transactions of the Royal Society B: Biological Sciences 367, 601–612.
| Carbon dioxide and the uneasy interactions of trees and savannah grasses.Crossref | GoogleScholarGoogle Scholar |
Bowman, DMJS, and Fensham, RJ (1991). Response of a monsoon-forest savanna boundary to fire protection, Weipa, northern Australia. Australian Journal of Ecology 16, 111–118.
| Response of a monsoon-forest savanna boundary to fire protection, Weipa, northern Australia.Crossref | GoogleScholarGoogle Scholar |
Bowman, DMJS, MacDermott, HJ, Nichols, SC, and Murphy, BP (2014). A grass–fire cycle eliminates an obligate-seeding tree in a tropical savanna. Ecology and Evolution 4, 4185–4194.
| A grass–fire cycle eliminates an obligate-seeding tree in a tropical savanna.Crossref | GoogleScholarGoogle Scholar |
Bultan, S, Nabel, JEMS, Hartung, K, Ganzenmüller, R, Xu, L, Saatchi, S, and Pongratz, J (2022). Tracking 21st century anthropogenic and natural carbon fluxes through model-data integration. Nature Communications 13, 5516.
| Tracking 21st century anthropogenic and natural carbon fluxes through model-data integration.Crossref | GoogleScholarGoogle Scholar |
Bureau of Meteorology (2006) Köppen climate classification (base climate related classification datasets). Available at http://www.bom.gov.au/climate/averages/climatology/gridded-data-info/metadata/md_koppen_classification.shtml [accessed 12 April 2023]
Bureau of Meteorology (2008) Australian average rainfall data from 1961 to 1990. Bioregional assessment source dataset. Available at https://data.gov.au/data/dataset/fd91f2d4-2cc8-4d5d-9f67-8fe8af1e2676 [accessed 12 April 2023]
Bureau of Meteorology (2019) Regional weather and climate guide: Cape York. Available at http://www.bom.gov.au/climate/climate-guides/guides/025-Cape-York-QLD-Climate-Guide.pdf [accessed 14 April 2023]
Bureau of Meteorology (2021) Rainfall variability (1900-2019). (Commonwealth of Australia) Available at http://www.bom.gov.au/jsp/ncc/climate_averages/rainfall-variability/index.jsp [accessed 12 April 2023]
Bureau of Meteorology (2022) Long-range weather and climate. Available at http://www.bom.gov.au/climate [accessed 11 April 2023]
Charles Darwin University (2021) NAFI: North Australian fire information website. (Charles Darwin University: Darwin, NT) Available at https://www.firenorth.org.au [accessed 12 April 2023]
Chianucci, F, Bajocco, S, and Ferrara, C (2021). Continuous observations of forest canopy structure using low-cost digital camera traps. Agricultural and Forest Meteorology 307, 108516.
| Continuous observations of forest canopy structure using low-cost digital camera traps.Crossref | GoogleScholarGoogle Scholar |
Cook GD, Liedloff AC, Murphy BP (2015) Predicting the effects of fire management on carbon stock dynamics using statistical and process-based modelling. In ‘Carbon accounting and savanna fire management’. (Eds BP Murphy, AC Edwards, CP Meyer, J Russell-Smith) pp. 295–315. (CSIRO Publishing: Melbourne, Vic., Australia)
Cowley R (2020) Woody cover change in grazing lands of northern Australia since 1988. Range Management Newsletter. Vol. 20. Available at https://austrangesoc.com.au/woody-cover-change-in-grazing-lands-of-northern-australia-since-1988 [accessed 14 April 2020]
Crowley, GM, and Garnett, ST (1998). Vegetation change in the grasslands and grassy woodlands of east-central Cape York Peninsula, Australia. Pacific Conservation Biology 4, 132–148.
| Vegetation change in the grasslands and grassy woodlands of east-central Cape York Peninsula, Australia.Crossref | GoogleScholarGoogle Scholar |
Crowley, GM, and Garnett, ST (2000). Changing fire management in the pastoral lands of Cape York Peninsula of northeast Australia, 1623 to 1996. Australian Geographical Studies 38, 10–26.
| Changing fire management in the pastoral lands of Cape York Peninsula of northeast Australia, 1623 to 1996.Crossref | GoogleScholarGoogle Scholar |
Crowley, G, Garnett, S, and Shephard, S (2009). Impact of storm-burning on Melaleuca viridiflora invasion of grasslands and grassy woodlands on Cape York Peninsula, Australia. Austral Ecology 34, 196–209.
| Impact of storm-burning on Melaleuca viridiflora invasion of grasslands and grassy woodlands on Cape York Peninsula, Australia.Crossref | GoogleScholarGoogle Scholar |
David, B, and Lourandos, H (1997). 37,000 years and more in tropical Australia: investigating long-term archaeological trends in Cape York Peninsula. Proceedings of the Prehistoric Society 63, 1–23.
| 37,000 years and more in tropical Australia: investigating long-term archaeological trends in Cape York Peninsula.Crossref | GoogleScholarGoogle Scholar |
Department of Environment and Science (2018) Pre-clearing Broad Vegetation Groups - Queensland Version 4.0 (14 Dec 2018). https://qldspatial.information.qld.gov.au/catalogue/ [accessed 22 June 2017, superseded by Version 6]
Department of Environment and Science (2022) Seasonal persistent green - Landsat, JRSRP algorithm Version 3.0, Australia coverage. Terrestrial Ecosystem Research Network. (Queensland Government: Brisbane) Available at https://portal.tern.org.au/metadata/TERN% 2Fdd359b61-3ce2-4cd5-bc63-d54d2d0e2509 [accessed 12 April 2023]
Donohue, RJ, Roderick, ML, McVicar, TR, and Farquhar, GD (2013). Impact of CO2 fertilization on maximum foliage cover across the globe’s warm, arid environments. Geophysical Research Letters 40, 3031–3035.
| Impact of CO2 fertilization on maximum foliage cover across the globe’s warm, arid environments.Crossref | GoogleScholarGoogle Scholar |
Duff, GA, Berryman, CA, and Eamus, D (1994). Growth, biomass allocation and foliar nutrient contents of two Eucalyptus species of the wet-dry tropics of Australia grown under CO2 enrichment. Functional Ecology 8, 502–508.
| Growth, biomass allocation and foliar nutrient contents of two Eucalyptus species of the wet-dry tropics of Australia grown under CO2 enrichment.Crossref | GoogleScholarGoogle Scholar |
Edwards, A, Archer, R, De Bruyn, P, Evans, J, Lewis, B, Vigilante, T, Whyte, S, and Russell-Smith, J (2021). Transforming fire management in northern Australia through successful implementation of savanna burning emissions reductions projects. Journal of Environmental Management 290, 112568.
| Transforming fire management in northern Australia through successful implementation of savanna burning emissions reductions projects.Crossref | GoogleScholarGoogle Scholar |
Felderhof, L, and Gillieson, D (2006). Comparison of fire patterns and fire frequency in two tropical savanna bioregions. Austral Ecology 31, 736–746.
| Comparison of fire patterns and fire frequency in two tropical savanna bioregions.Crossref | GoogleScholarGoogle Scholar |
Fensham, RJ, and Holman, JE (1999). Temporal and spatial patterns in drought-related tree dieback in Australian savanna. Journal of Applied Ecology 36, 1035–1050.
| Temporal and spatial patterns in drought-related tree dieback in Australian savanna.Crossref | GoogleScholarGoogle Scholar |
Fensham, RJ, Fairfax, RJ, and Ward, DP (2009). Drought-induced tree death in savanna. Global Change Biology 15, 380–387.
| Drought-induced tree death in savanna.Crossref | GoogleScholarGoogle Scholar |
Fisher, A, Scarth, P, Armston, J, and Danaher, T (2018). Relating foliage and crown projective cover in Australian tree stands. Agricultural and Forest Meteorology 259, 39–47.
| Relating foliage and crown projective cover in Australian tree stands.Crossref | GoogleScholarGoogle Scholar |
Flood, N, Watson, F, and Collett, L (2019). Using a U-net convolutional neural network to map woody vegetation extent from high resolution satellite imagery across Queensland, Australia. International Journal of Applied Earth Observation and Geoinformation 82, 101897.
| Using a U-net convolutional neural network to map woody vegetation extent from high resolution satellite imagery across Queensland, Australia.Crossref | GoogleScholarGoogle Scholar |
García Criado, M, Myers-Smith, IH, Bjorkman, AD, Lehmann, CER, and Stevens, N (2020). Woody plant encroachment intensifies under climate change across tundra and savanna biomes. Global Ecology and Biogeography 29, 925–943.
| Woody plant encroachment intensifies under climate change across tundra and savanna biomes.Crossref | GoogleScholarGoogle Scholar |
Guerreiro, MF, Nicodemo, MLF, and Porfírio-da-Silva, V (2015). Vulnerability of ten Eucalyptus varieties to predation by cattle in a silvopastoral system. Agroforestry Systems 89, 743–749.
| Vulnerability of ten Eucalyptus varieties to predation by cattle in a silvopastoral system.Crossref | GoogleScholarGoogle Scholar |
Hamada, Y, Szoldatits, K, Grippo, M, and Hartmann, HM (2019). Remotely sensed spatial structure as an indicator of internal changes of vegetation communities in desert landscapes. Remote Sensing 11, 1495.
| Remotely sensed spatial structure as an indicator of internal changes of vegetation communities in desert landscapes.Crossref | GoogleScholarGoogle Scholar |
Haverd, V, Smith, B, Canadell, JG, Cuntz, M, Mikaloff-Fletcher, S, Farquhar, G, Woodgate, W, Briggs, PR, and Trudinger, CM (2020). Higher than expected CO2 fertilization inferred from leaf to global observations. Global Change Biology 26, 2390–2402.
| Higher than expected CO2 fertilization inferred from leaf to global observations.Crossref | GoogleScholarGoogle Scholar |
Hijmans RJ, van Etten J (2012) raster: Geographic analysis and modeling with raster data. R package version 2.0-12. Available at http://CRAN.R-project.org/package=raster/ [accessed 4 Jul 2022]
Holmes, J (2010). The multifunctional transition in Australia’s tropical savannas: the emergence of consumption, protection and indigenous values. Geographical Research 48, 265–280.
| The multifunctional transition in Australia’s tropical savannas: the emergence of consumption, protection and indigenous values.Crossref | GoogleScholarGoogle Scholar |
Hovenden, MJ, and Williams, AL (2010). The impacts of rising CO2 concentrations on Australian terrestrial species and ecosystems. Austral Ecology 35, 665–684.
| The impacts of rising CO2 concentrations on Australian terrestrial species and ecosystems.Crossref | GoogleScholarGoogle Scholar |
Jiang, M, Caldararu, S, Zhang, H, Fleischer, K, Crous, KY, Yang, J, De Kauwe, MG, Ellsworth, DS, Reich, PB, Tissue, DT, Zaehle, S, and Medlyn, BE (2020a). Low phosphorus supply constrains plant responses to elevated CO2: a meta-analysis. Global Change Biology 26, 5856–5873.
| Low phosphorus supply constrains plant responses to elevated CO2: a meta-analysis.Crossref | GoogleScholarGoogle Scholar |
Jiang, M, Medlyn, BE, Drake, JE, Duursma, RA, Anderson, IC, Barton, CVM, Boer, MM, Carrillo, Y, Castañeda-Gómez, L, Collins, L, Crous, KY, De Kauwe, MG, dos Santos, BM, Emmerson, KM, Facey, SL, Gherlenda, AN, Gimeno, TE, Hasegawa, S, Johnson, SN, Kännaste, A, Macdonald, CA, Mahmud, K, Moore, BD, Nazaries, L, Neilson, EHJ, Nielsen, UN, Niinemets, Ü, Noh, NJ, Ochoa-Hueso, R, Pathare, VS, Pendall, E, Pihlblad, J, Piñeiro, J, Powell, JR, Power, SA, Reich, PB, Renchon, AA, Riegler, M, Rinnan, R, Rymer, PD, Salomón, RL, Singh, BK, Smith, B, Tjoelker, MG, Walker, JKM, Wujeska-Klause, A, Yang, J, Zaehle, S, and Ellsworth, DS (2020b). The fate of carbon in a mature forest under carbon dioxide enrichment. Nature 580, 227–231.
| The fate of carbon in a mature forest under carbon dioxide enrichment.Crossref | GoogleScholarGoogle Scholar |
Kamal, M, Phinn, S, and Johansen, K (2014). Characterizing the spatial structure of mangrove features for optimizing image-based mangrove mapping. Remote Sensing 6, 984–1006.
| Characterizing the spatial structure of mangrove features for optimizing image-based mangrove mapping.Crossref | GoogleScholarGoogle Scholar |
Lankester, AJ (2006) Landholder experiences and perceptions of the extent, onset and causes of woody vegetation change: Northern Gulf scoping study. Final Report to the Tropical Savannas Cooperative Research Centre. (James Cook University: Townsville, Qld) Available at https://www.researchgate.net/profile/Ally_Lankester/publication/265162983_Landholder_perceptions_of_vegetation_change_in_the_Northern_Gulf_Australia/links/540172dc0cf23d9765a4964e.pdf [accessed 14 April 2023]
Laughlin, GP, Zuo, H, Walcott, J, and Bugg, AL (2003). The rainfall reliability wizard—a new tool to rapidly analyse spatial rainfall reliability with examples. Environmental Modelling & Software 18, 49–57.
| The rainfall reliability wizard—a new tool to rapidly analyse spatial rainfall reliability with examples.Crossref | GoogleScholarGoogle Scholar |
Liao, Z, Van Dijk, AIJM, He, B, Larraondo, PR, and Scarth, PF (2020). Woody vegetation cover, height and biomass at 25-m resolution across Australia derived from multiple site, airborne and satellite observations. International Journal of Applied Earth Observation and Geoinformation 93, 102209.
| Woody vegetation cover, height and biomass at 25-m resolution across Australia derived from multiple site, airborne and satellite observations.Crossref | GoogleScholarGoogle Scholar |
Liedloff, AC, Coughenour, MB, Ludwig, JA, and Dyer, R (2001). Modelling the trade-off between fire and grazing in a tropical savanna landscape, northern Australia. Environment International 27, 173–180.
| Modelling the trade-off between fire and grazing in a tropical savanna landscape, northern Australia.Crossref | GoogleScholarGoogle Scholar |
Lindenmayer DB, Likens GE (2018) ‘Effective ecological monitoring.’ 2nd edn. (CSIRO Publishing: Melbourne, Vic., Australia)
Ma, X, Huete, A, Cleverly, J, Eamus, D, Chevallier, F, Joiner, J, Poulter, B, Zhang, Y, Guanter, L, Meyer, W, Xie, Z, and Ponce-Campos, G (2016). Drought rapidly diminishes the large net CO2 uptake in 2011 over semi-arid Australia. Scientific Reports 6, 37747.
| Drought rapidly diminishes the large net CO2 uptake in 2011 over semi-arid Australia.Crossref | GoogleScholarGoogle Scholar |
McCarthy, HR, Oren, R, Finzi, AC, Ellsworth, DS, Kim, H-S, Johnsen, KH, and Millar, B (2007). Temporal dynamics and spatial variability in the enhancement of canopy leaf area under elevated atmospheric CO2. Global Change Biology 13, 2479–2497.
| Temporal dynamics and spatial variability in the enhancement of canopy leaf area under elevated atmospheric CO2.Crossref | GoogleScholarGoogle Scholar |
Miller M (2000) Fire autecology. In ‘Wildland fire in ecosystems: effects of fire on flora’. (Eds JK Brown, JK Smith) pp. 9–34. (Rocky Mountain Research Station: Fort Collins, CO, USA)
Miller BP, Murphy BP (2017) Fire and Australian vegetation. In ‘Australian vegetation’. 3rd edn. (Ed. DA Keith) pp. 113–134. (Cambridge University Press: Cambridge, UK)
Murphy, BP, Lehmann, CER, Russell-Smith, J, and Lawes, MJ (2014). Fire regimes and woody biomass dynamics in Australian savannas. Journal of Biogeography 41, 133–144.
| Fire regimes and woody biomass dynamics in Australian savannas.Crossref | GoogleScholarGoogle Scholar |
Murphy BP, Edwards A, Meyer CP, Russell-Smith J (Eds) (2015) ‘Carbon accounting and savanna fire management.’ (CSIRO: Australia)
Murphy SA, Shephard S, Crowley GM, Garnett ST, Webster P, Cooper W, Jensen R (2021) Pre-management actions baseline report for Artemis Antbed Parrot Nature Refuge. (National Environmental Science Program, Threatened Species Recovery Hub: Brisbane, Qld) Available at https://www.nespthreatenedspecies.edu.au/publications-and-tools/pre-management-actions-baseline-report-for-artemis-antbed-parrot-nature-refuge [accessed 14 April 2023]
Myers, BA, Williams, RJ, Fordyce, I, Duff, GA, and Eamus, D (1998). Does irrigation affect leaf phenology in deciduous and evergreen trees of the savannas of northern Australia? Australian Journal of Ecology 23, 329–339.
| Does irrigation affect leaf phenology in deciduous and evergreen trees of the savannas of northern Australia?Crossref | GoogleScholarGoogle Scholar |
Neldner, VJ, Fensham, RJ, Clarkson, JR, and Stanton, JP (1997). The natural grasslands of Cape York Peninsula, Australia: description, distribution and conservation status. Biological Conservation 81, 121–136.
| The natural grasslands of Cape York Peninsula, Australia: description, distribution and conservation status.Crossref | GoogleScholarGoogle Scholar |
Niinemets, Ü, Flexas, J, and Peñuelas, J (2011). Evergreens favored by higher responsiveness to increased CO2. Trends in Ecology & Evolution 26, 136–142.
| Evergreens favored by higher responsiveness to increased CO2.Crossref | GoogleScholarGoogle Scholar |
O’Grady, AP, Chen, X, Eamus, D, and Hutley, LB (2000). Composition, leaf area index and standing biomass of eucalypt open forests near Darwin in the Northern Territory, Australia. Australian Journal of Botany 48, 629–638.
| Composition, leaf area index and standing biomass of eucalypt open forests near Darwin in the Northern Territory, Australia.Crossref | GoogleScholarGoogle Scholar |
Ondei, S, Prior, LD, Vigilante, T, and Bowman, DMJS (2017). Fire and cattle disturbance affects vegetation structure and rain forest expansion into savanna in the Australian monsoon tropics. Journal of Biogeography 44, 2331–2342.
| Fire and cattle disturbance affects vegetation structure and rain forest expansion into savanna in the Australian monsoon tropics.Crossref | GoogleScholarGoogle Scholar |
Pawley, MDM, and McArdle, BH (2021). Inferences with spatial autocorrelation. Austral Ecology 46, 942–949.
| Inferences with spatial autocorrelation.Crossref | GoogleScholarGoogle Scholar |
Pebesma, EJ (2004). Multivariable geostatistics in S: the gstat package. Computers & Geosciences 30, 683–691.
| Multivariable geostatistics in S: the gstat package.Crossref | GoogleScholarGoogle Scholar |
Perry, JJ, Cook, GD, Graham, E, Meyer, CP, Murphy, HT, and VanDerWal, J (2020). Regional seasonality of fire size and fire weather conditions across Australia’s northern savanna. International Journal of Wildland Fire 29, 1–10.
| Regional seasonality of fire size and fire weather conditions across Australia’s northern savanna.Crossref | GoogleScholarGoogle Scholar |
Piao, S, Wang, X, Park, T, Chen, C, Lian, X, He, Y, Bjerke, JW, Chen, A, Ciais, P, Tømmervik, H, Nemani, RR, and Myneni, RB (2020). Characteristics, drivers and feedbacks of global greening. Nature Reviews Earth & Environment 1, 14–27.
| Characteristics, drivers and feedbacks of global greening.Crossref | GoogleScholarGoogle Scholar |
Pillay, T, and Ward, D (2021). Grass competition is more important than fire for suppressing encroachment of Acacia sieberiana seedlings. Plant Ecology 222, 149–158.
| Grass competition is more important than fire for suppressing encroachment of Acacia sieberiana seedlings.Crossref | GoogleScholarGoogle Scholar |
Pisek, J, Řezníčková, L, Adamson, K, and Ellsworth, DS (2021). Leaf inclination angle and foliage clumping in an evergreen broadleaf Eucalyptus forest under elevated atmospheric CO2. Australian Journal of Botany 69, 622–629.
| Leaf inclination angle and foliage clumping in an evergreen broadleaf Eucalyptus forest under elevated atmospheric CO2.Crossref | GoogleScholarGoogle Scholar |
Prior, LD, Brook, BW, Williams, RJ, Werner, PA, Bradshaw, CJA, and Bowman, DMJS (2006). Environmental and allometric drivers of tree growth rates in a north Australian savanna. Forest Ecology and Management 234, 164–180.
| Environmental and allometric drivers of tree growth rates in a north Australian savanna.Crossref | GoogleScholarGoogle Scholar |
Prior, LD, Murphy, BP, and Russell-Smith, J (2009). Environmental and demographic correlates of tree recruitment and mortality in north Australian savannas. Forest Ecology and Management 257, 66–74.
| Environmental and demographic correlates of tree recruitment and mortality in north Australian savannas.Crossref | GoogleScholarGoogle Scholar |
Prior, LD, Whiteside, TG, Williamson, GJ, Bartolo, RE, and Bowman, DMJS (2020). Multi-decadal stability of woody cover in a mesic eucalypt savanna in the Australian monsoon tropics. Austral Ecology 45, 621–635.
| Multi-decadal stability of woody cover in a mesic eucalypt savanna in the Australian monsoon tropics.Crossref | GoogleScholarGoogle Scholar |
Queensland Herbarium (2018) Remnant 2017 Broad Vegetation Groups of Queensland (BVG) Version 4.0 (14 Dec 2018). (Department of Science, Information Technology and Innovation: Brisbane) Available at http://qldspatial.information.qld.gov.au/catalogue [accessed 4 July 2022, superceded by version 5.2]
Rahman, M, Islam, M, Gebrekirstos, A, and Bräuning, A (2019). Trends in tree growth and intrinsic water-use efficiency in the tropics under elevated CO2 and climate change. Trees 33, 623–640.
| Trends in tree growth and intrinsic water-use efficiency in the tropics under elevated CO2 and climate change.Crossref | GoogleScholarGoogle Scholar |
R Core Team (2020) R: A language and environment for statistical computing. Version 4.1.3 (2020-10-10). (R Foundation for Statistical Computing: Vienna, Austria) Available at https://www.R-project.org/ [accessed 9 December 2020]
Rifai, SW, De Kauwe, MG, Ukkola, AM, Cernusak, LA, Meir, P, Medlyn, BE, and Pitman, AJ (2022). Thirty-eight years of CO2 fertilization has outpaced growing aridity to drive greening of Australian woody ecosystems. Biogeosciences 19, 491–515.
| Thirty-eight years of CO2 fertilization has outpaced growing aridity to drive greening of Australian woody ecosystems.Crossref | GoogleScholarGoogle Scholar |
Riginos, C (2009). Grass competition suppresses savanna tree growth across multiple demographic stages. Ecology 90, 335–340.
| Grass competition suppresses savanna tree growth across multiple demographic stages.Crossref | GoogleScholarGoogle Scholar |
Russell-Smith, J, Stanton, PJ, Edwards, AC, and Whitehead, PJ (2004a). Rain forest invasion of eucalypt-dominated woodland savanna, Iron Range, north-eastern Australia: II. Rates of landscape change. Journal of Biogeography 31, 1305–1316.
| Rain forest invasion of eucalypt-dominated woodland savanna, Iron Range, north-eastern Australia: II. Rates of landscape change.Crossref | GoogleScholarGoogle Scholar |
Russell-Smith, J, Stanton, PJ, Whitehead, PJ, and Edwards, A (2004b). Rain forest invasion of eucalypt-dominated woodland savanna, Iron Range, north-eastern Australia: I. Successional processes. Journal of Biogeography 31, 1293–1303.
| Rain forest invasion of eucalypt-dominated woodland savanna, Iron Range, north-eastern Australia: I. Successional processes.Crossref | GoogleScholarGoogle Scholar |
Scarth, P, Armston, J, Flood, N, Denham, R, Collett, L, Watson, F, Trevithick, B, Muir, J, Goodwin, N, Tindall, D, and Phinn, S (2015). Operational application of the landsat timeseries to address large area landcover understanding. The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XL-3/W3, 571–575.
| Operational application of the landsat timeseries to address large area landcover understanding.Crossref | GoogleScholarGoogle Scholar |
Sharp, BR, and Bowman, DMJS (2004). Net woody vegetation increase confined to seasonally inundated lowlands in an Australian tropical savanna, Victoria River District, Northern Territory. Austral Ecology 29, 667–683.
| Net woody vegetation increase confined to seasonally inundated lowlands in an Australian tropical savanna, Victoria River District, Northern Territory.Crossref | GoogleScholarGoogle Scholar |
Solana-Gutiérrez, J, and Merino-de-Miguel, S (2011). A variogram model comparison for predicting forest changes. Procedia Environmental Sciences 7, 383–388.
| A variogram model comparison for predicting forest changes.Crossref | GoogleScholarGoogle Scholar |
Stanton, JP (1992). J. P. Thomson oration: The neglected lands: recent changes in the ecosystem of Cape York Peninsula and the challenge of their management. Queensland Geographical Journal 7, 1–18.
Stevens, N, Erasmus, BFN, Archibald, S, and Bond, WJ (2016). Woody encroachment over 70 years in South African savannahs: overgrazing, global change or extinction aftershock? Philosophical Transactions of the Royal Society B: Biological Sciences 371, 20150437.
| Woody encroachment over 70 years in South African savannahs: overgrazing, global change or extinction aftershock?Crossref | GoogleScholarGoogle Scholar |
Stevens, N., Lehmann, C. E. R., Murphy, B. P., and Durigan, G. (2017). Savanna woody encroachment is widespread across three continents Global Change Biology 23, 235–244.
| Savanna woody encroachment is widespread across three continentsCrossref | GoogleScholarGoogle Scholar |
Thomas, SC, and Martin, AR (2012). Carbon content of tree tissues: a synthesis. Forests 3, 332–352.
| Carbon content of tree tissues: a synthesis.Crossref | GoogleScholarGoogle Scholar |
van Langevelde, F, van de Vijver, CADM, Kumar, L, van de Koppel, J, de Ridder, N, van Andel, J, Skidmore, AK, Hearne, JW, Stroosnijder, L, Bond, WJ, Prins, HHT, and Rietkerk, M (2003). Effects of fire and herbivory on the stability of savanna ecosystems. Ecology 84, 337–350.
| Effects of fire and herbivory on the stability of savanna ecosystems.Crossref | GoogleScholarGoogle Scholar |
Werner, PA, and Prior, LD (2013). Demography and growth of subadult savanna trees: interactions of life history, size, fire season, and grassy understory. Ecological Monographs 83, 67–93.
| Demography and growth of subadult savanna trees: interactions of life history, size, fire season, and grassy understory.Crossref | GoogleScholarGoogle Scholar |
Whitehead, D, and Beadle, CL (2004). Physiological regulation of productivity and water use in Eucalyptus: a review. Forest Ecology and Management 193, 113–140.
| Physiological regulation of productivity and water use in Eucalyptus: a review.Crossref | GoogleScholarGoogle Scholar |
Wood SN (2019) mgcv: Mixed GAM Computation Vehicle with Automatic Smoothness Estimation. Version 1.8-40. Available at https://cran.r-project.org/web/packages/mgcv/index.html [accessed 7 June 2023]
Zhu, Z, Piao, S, Myneni, RB, Huang, M, Zeng, Z, Canadell, JG, Ciais, P, Sitch, S, Friedlingstein, P, Arneth, A, Cao, C, Cheng, L, Kato, E, Koven, C, Li, Y, Lian, X, Liu, Y, Liu, R, Mao, J, Pan, Y, Peng, S, Peñuelas, J, Poulter, B, Pugh, TAM, Stocker, BD, Viovy, N, Wang, X, Wang, Y, Xiao, Z, Yang, H, Zaehle, S, and Zeng, N (2016). Greening of the Earth and its drivers. Nature Climate Change 6, 791–795.
| Greening of the Earth and its drivers.Crossref | GoogleScholarGoogle Scholar |
