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Ashton, Peter

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Ashton

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Ashton, Peter
Author's Publications: search.filters.isAuthorOfPublication.9bf4d5b9-eff0-4f84-a3b5-9e729d62bb39

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    Long-term carbon sink in Borneo’s forests halted by drought and vulnerable to edge effects
    (Nature Publishing Group UK, 2017) Qie, Lan; Lewis, Simon L.; Sullivan, Martin J. P.; Lopez-Gonzalez, Gabriela; Pickavance, Georgia C.; Sunderland, Terry; Ashton, Peter; Hubau, Wannes; Abu Salim, Kamariah; Aiba, Shin-Ichiro; Banin, Lindsay F.; Berry, Nicholas; Brearley, Francis Q.; Burslem, David F. R. P.; Dančák, Martin; Davies, Stuart J.; Fredriksson, Gabriella; Hamer, Keith C.; Hédl, Radim; Kho, Lip Khoon; Kitayama, Kanehiro; Krisnawati, Haruni; Lhota, Stanislav; Malhi, Yadvinder; Maycock, Colin; Metali, Faizah; Mirmanto, Edi; Nagy, Laszlo; Nilus, Reuben; Ong, Robert; Pendry, Colin A.; Poulsen, Axel Dalberg; Primack, Richard B.; Rutishauser, Ervan; Samsoedin, Ismayadi; Saragih, Bernaulus; Sist, Plinio; Slik, J. W. Ferry; Sukri, Rahayu Sukmaria; Svátek, Martin; Tan, Sylvester; Tjoa, Aiyen; van Nieuwstadt, Mark; Vernimmen, Ronald R. E.; Yassir, Ishak; Kidd, Petra Susan; Fitriadi, Muhammad; Ideris, Nur Khalish Hafizhah; Serudin, Rafizah Mat; Abdullah Lim, Layla Syaznie; Saparudin, Muhammad Shahruney; Phillips, Oliver L.
    Less than half of anthropogenic carbon dioxide emissions remain in the atmosphere. While carbon balance models imply large carbon uptake in tropical forests, direct on-the-ground observations are still lacking in Southeast Asia. Here, using long-term plot monitoring records of up to half a century, we find that intact forests in Borneo gained 0.43 Mg C ha−1 per year (95% CI 0.14–0.72, mean period 1988–2010) above-ground live biomass. These results closely match those from African and Amazonian plot networks, suggesting that the world’s remaining intact tropical forests are now en masse out-of-equilibrium. Although both pan-tropical and long-term, the sink in remaining intact forests appears vulnerable to climate and land use changes. Across Borneo the 1997–1998 El Niño drought temporarily halted the carbon sink by increasing tree mortality, while fragmentation persistently offset the sink and turned many edge-affected forests into a carbon source to the atmosphere.
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    Author Correction: Long-term carbon sink in Borneo’s forests halted by drought and vulnerable to edge effects
    (Nature Publishing Group UK, 2018) Qie, Lan; Lewis, Simon L.; Sullivan, Martin J. P.; Lopez-Gonzalez, Gabriela; Pickavance, Georgia C.; Sunderland, Terry; Ashton, Peter; Hubau, Wannes; Abu Salim, Kamariah; Aiba, Shin-Ichiro; Banin, Lindsay F.; Berry, Nicholas; Brearley, Francis Q.; Burslem, David F. R. P.; Dančák, Martin; Davies, Stuart J.; Fredriksson, Gabriella; Hamer, Keith C.; Hédl, Radim; Kho, Lip Khoon; Kitayama, Kanehiro; Krisnawati, Haruni; Lhota, Stanislav; Malhi, Yadvinder; Maycock, Colin; Metali, Faizah; Mirmanto, Edi; Nagy, Laszlo; Nilus, Reuben; Ong, Robert; Pendry, Colin A.; Poulsen, Axel Dalberg; Primack, Richard B.; Rutishauser, Ervan; Samsoedin, Ismayadi; Saragih, Bernaulus; Sist, Plinio; Ferry Slik, J. W.; Sukri, Rahayu Sukmaria; Svátek, Martin; Tan, Sylvester; Tjoa, Aiyen; van Nieuwstadt, Mark; Vernimmen, Ronald R. E.; Yassir, Ishak; Kidd, Petra Susan; Fitriadi, Muhammad; Ideris, Nur Khalish Hafizhah; Serudin, Rafizah Mat; Abdullah Lim, Layla Syaznie; Saparudin, Muhammad Shahruney; Phillips, Oliver L.
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    Field methods for sampling tree height for tropical forest biomass estimation
    (John Wiley and Sons Inc., 2018) Sullivan, Martin J. P.; Lewis, Simon L.; Hubau, Wannes; Qie, Lan; Baker, Timothy R.; Banin, Lindsay F.; Chave, Jerôme; Cuni‐Sanchez, Aida; Feldpausch, Ted R.; Lopez‐Gonzalez, Gabriela; Arets, Eric; Ashton, Peter; Bastin, Jean‐François; Berry, Nicholas J.; Bogaert, Jan; Boot, Rene; Brearley, Francis Q.; Brienen, Roel; Burslem, David F. R. P.; de Canniere, Charles; Chudomelová, Markéta; Dančák, Martin; Ewango, Corneille; Hédl, Radim; Lloyd, Jon; Makana, Jean‐Remy; Malhi, Yadvinder; Marimon, Beatriz S.; Junior, Ben Hur Marimon; Metali, Faizah; Moore, Sam; Nagy, Laszlo; Vargas, Percy Nuñez; Pendry, Colin A.; Ramírez‐Angulo, Hirma; Reitsma, Jan; Rutishauser, Ervan; Salim, Kamariah Abu; Sonké, Bonaventure; Sukri, Rahayu S.; Sunderland, Terry; Svátek, Martin; Umunay, Peter M.; Martinez, Rodolfo Vasquez; Vernimmen, Ronald R. E.; Torre, Emilio Vilanova; Vleminckx, Jason; Vos, Vincent; Phillips, Oliver L.
    Abstract Quantifying the relationship between tree diameter and height is a key component of efforts to estimate biomass and carbon stocks in tropical forests. Although substantial site‐to‐site variation in height–diameter allometries has been documented, the time consuming nature of measuring all tree heights in an inventory plot means that most studies do not include height, or else use generic pan‐tropical or regional allometric equations to estimate height.Using a pan‐tropical dataset of 73 plots where at least 150 trees had in‐field ground‐based height measurements, we examined how the number of trees sampled affects the performance of locally derived height–diameter allometries, and evaluated the performance of different methods for sampling trees for height measurement.Using cross‐validation, we found that allometries constructed with just 20 locally measured values could often predict tree height with lower error than regional or climate‐based allometries (mean reduction in prediction error = 0.46 m). The predictive performance of locally derived allometries improved with sample size, but with diminishing returns in performance gains when more than 40 trees were sampled. Estimates of stand‐level biomass produced using local allometries to estimate tree height show no over‐ or under‐estimation bias when compared with biomass estimates using field measured heights. We evaluated five strategies to sample trees for height measurement, and found that sampling strategies that included measuring the heights of the ten largest diameter trees in a plot outperformed (in terms of resulting in local height–diameter models with low height prediction error) entirely random or diameter size‐class stratified approaches.Our results indicate that even limited sampling of heights can be used to refine height–diameter allometries. We recommend aiming for a conservative threshold of sampling 50 trees per location for height measurement, and including the ten trees with the largest diameter in this sample.
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    Diversity and carbon storage across the tropical forest biome
    (Nature Publishing Group, 2017) Sullivan, Martin J. P.; Talbot, Joey; Lewis, Simon L.; Phillips, Oliver L.; Qie, Lan; Begne, Serge K.; Chave, Jerôme; Cuni-Sanchez, Aida; Hubau, Wannes; Lopez-Gonzalez, Gabriela; Miles, Lera; Monteagudo-Mendoza, Abel; Sonké, Bonaventure; Sunderland, Terry; ter Steege, Hans; White, Lee J. T.; Affum-Baffoe, Kofi; Aiba, Shin-ichiro; de Almeida, Everton Cristo; de Oliveira, Edmar Almeida; Alvarez-Loayza, Patricia; Dávila, Esteban Álvarez; Andrade, Ana; Aragão, Luiz E. O. C.; Ashton, Peter; Aymard C., Gerardo A.; Baker, Timothy R.; Balinga, Michael; Banin, Lindsay F.; Baraloto, Christopher; Bastin, Jean-Francois; Berry, Nicholas; Bogaert, Jan; Bonal, Damien; Bongers, Frans; Brienen, Roel; Camargo, José Luís C.; Cerón, Carlos; Moscoso, Victor Chama; Chezeaux, Eric; Clark, Connie J.; Pacheco, Álvaro Cogollo; Comiskey, James A.; Valverde, Fernando Cornejo; Coronado, Eurídice N. Honorio; Dargie, Greta; Davies, Stuart J.; De Canniere, Charles; Djuikouo K., Marie Noel; Doucet, Jean-Louis; Erwin, Terry L.; Espejo, Javier Silva; Ewango, Corneille E. N.; Fauset, Sophie; Feldpausch, Ted R.; Herrera, Rafael; Gilpin, Martin; Gloor, Emanuel; Hall, Jefferson S.; Harris, David J.; Hart, Terese B.; Kartawinata, Kuswata; Kho, Lip Khoon; Kitayama, Kanehiro; Laurance, Susan G. W.; Laurance, William F.; Leal, Miguel E.; Lovejoy, Thomas; Lovett, Jon C.; Lukasu, Faustin Mpanya; Makana, Jean-Remy; Malhi, Yadvinder; Maracahipes, Leandro; Marimon, Beatriz S.; Junior, Ben Hur Marimon; Marshall, Andrew R.; Morandi, Paulo S.; Mukendi, John Tshibamba; Mukinzi, Jaques; Nilus, Reuben; Vargas, Percy Núñez; Camacho, Nadir C. Pallqui; Pardo, Guido; Peña-Claros, Marielos; Pétronelli, Pascal; Pickavance, Georgia C.; Poulsen, Axel Dalberg; Poulsen, John R.; Primack, Richard B.; Priyadi, Hari; Quesada, Carlos A.; Reitsma, Jan; Réjou-Méchain, Maxime; Restrepo, Zorayda; Rutishauser, Ervan; Salim, Kamariah Abu; Salomão, Rafael P.; Samsoedin, Ismayadi; Sheil, Douglas; Sierra, Rodrigo; Silveira, Marcos; Slik, J. W. Ferry; Steel, Lisa; Taedoumg, Hermann; Tan, Sylvester; Terborgh, John W.; Thomas, Sean C.; Toledo, Marisol; Umunay, Peter M.; Gamarra, Luis Valenzuela; Vieira, Ima Célia Guimarães; Vos, Vincent A.; Wang, Ophelia; Willcock, Simon; Zemagho, Lise
    Tropical forests are global centres of biodiversity and carbon storage. Many tropical countries aspire to protect forest to fulfil biodiversity and climate mitigation policy targets, but the conservation strategies needed to achieve these two functions depend critically on the tropical forest tree diversity-carbon storage relationship. Assessing this relationship is challenging due to the scarcity of inventories where carbon stocks in aboveground biomass and species identifications have been simultaneously and robustly quantified. Here, we compile a unique pan-tropical dataset of 360 plots located in structurally intact old-growth closed-canopy forest, surveyed using standardised methods, allowing a multi-scale evaluation of diversity-carbon relationships in tropical forests. Diversity-carbon relationships among all plots at 1 ha scale across the tropics are absent, and within continents are either weak (Asia) or absent (Amazonia, Africa). A weak positive relationship is detectable within 1 ha plots, indicating that diversity effects in tropical forests may be scale dependent. The absence of clear diversity-carbon relationships at scales relevant to conservation planning means that carbon-centred conservation strategies will inevitably miss many high diversity ecosystems. As tropical forests can have any combination of tree diversity and carbon stocks both require explicit consideration when optimising policies to manage tropical carbon and biodiversity.
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    Assessing Evidence for a Pervasive Alteration in Tropical Tree Communities
    (Public Library of Science, 2008) Chave, Jérôme; Condit, Richard; Muller-Landau, Helene C.; Thomas, Sean C.; Bunyavejchewin, Sarayudh; Co, Leonardo L.; Dattaraja, Handanakere S.; Esufali, Shameema; Ewango, Corneille E. N.; Feeley, Kenneth J.; Foster, Robin B.; Gunatilleke, Nimal; Gunatilleke, Savitri; Hall, Pamela; Hart, Terese B.; Hernández, Consuelo; Hubbell, Stephen P.; Itoh, Akira; Kiratiprayoon, Somboon; LaFrankie, James V.; Loo de Lao, Suzanne; Makana, Jean-Rémy; Noor, Md. Nur Supardi; Kassim, Abdul Rahman; Samper, Cristián; Sukumar, Raman; Suresh, Hebbalalu S.; Tan, Sylvester; Thompson, Jill; Tongco, Ma. Dolores C.; Valencia, Renato; Vallejo, Martha; Villa, Gorky; Yamakura, Takuo; Zimmerman, Jess K.; Losos, Elizabeth C.; Ashton, Peter; Davies, Stuart J.
    In Amazonian tropical forests, recent studies have reported increases in aboveground biomass and in primary productivity, as well as shifts in plant species composition favouring fast-growing species over slow-growing ones. This pervasive alteration of mature tropical forests was attributed to global environmental change, such as an increase in atmospheric \(CO_2\) concentration, nutrient deposition, temperature, drought frequency, and/or irradiance. We used standardized, repeated measurements of over 2 million trees in ten large (16–52 ha each) forest plots on three continents to evaluate the generality of these findings across tropical forests. Aboveground biomass increased at seven of our ten plots, significantly so at four plots, and showed a large decrease at a single plot. Carbon accumulation pooled across sites was significant \((+0.24 MgC ha^{−1} y^{−1}\), 95% confidence intervals \([0.07, 0.39] MgC ha^{−1} y^{−1})\), but lower than reported previously for Amazonia. At three sites for which we had data for multiple census intervals, we found no concerted increase in biomass gain, in conflict with the increased productivity hypothesis. Over all ten plots, the fastest-growing quartile of species gained biomass (+0.33 [0.09, 0.55] % \(y^{−1})\) compared with the tree community as a whole (+0.15 % \(y^{−1})\); however, this significant trend was due to a single plot. Biomass of slow-growing species increased significantly when calculated over all plots (+0.21 [0.02, 0.37] % \(y^{−1})\), and in half of our plots when calculated individually. Our results do not support the hypothesis that fast-growing species are consistently increasing in dominance in tropical tree communities. Instead, they suggest that our plots may be simultaneously recovering from past disturbances and affected by changes in resource availability. More long-term studies are necessary to clarify the contribution of global change to the functioning of tropical forests.