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  • 1
    Online Resource
    Online Resource
    The Royal Society ; 2004
    In:  Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences Vol. 359, No. 1443 ( 2004-03-29), p. 309-310
    In: Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences, The Royal Society, Vol. 359, No. 1443 ( 2004-03-29), p. 309-310
    Abstract: This issue is based on the proceedings of a symposium on ‘Tropical Forests and Global Atmospheric Change’ that was held at the Association for Tropical Biology annual meeting in Panama City, Panama, in July 2002. Our overall goal was to explore how the world's most biodiverse ecosystems might fare in an era of rapid atmospheric change. To achieve this we needed to ask original thinkers from a wide range of disciplines to focus on this common concern, often using new field data or new syntheses of existing data. Several researchers who could not attend the meeting were also invited to contribute to this Theme Issue which builds on advances in several distinct scientific disciplines.
    Type of Medium: Online Resource
    ISSN: 0962-8436 , 1471-2970
    RVK:
    Language: English
    Publisher: The Royal Society
    Publication Date: 2004
    detail.hit.zdb_id: 1462620-2
    SSG: 12
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  • 2
    Online Resource
    Online Resource
    The Royal Society ; 2004
    In:  Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences Vol. 359, No. 1443 ( 2004-03-29), p. 353-365
    In: Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences, The Royal Society, Vol. 359, No. 1443 ( 2004-03-29), p. 353-365
    Abstract: A previous study by Phillips et al . of changes in the biomass of permanent sample plots in Amazonian forests was used to infer the presence of a regional carbon sink. However, these results generated a vigorous debate about sampling and methodological issues. Therefore we present a new analysis of biomass change in old–growth Amazonian forest plots using updated inventory data. We find that across 59 sites, the above–ground dry biomass in trees that are more than 10 cm in diameter (AGB) has increased since plot establishment by 1.22 ± 0.43 Mg per hectare per year (ha −1 yr −1 ), where 1 ha = 10 4 m 2 ), or 0.98 ± 0.38 Mg ha −1 yr −1 if individual plot values are weighted by the number of hectare years of monitoring. This significant increase is neither confounded by spatial or temporal variation in wood specific gravity, nor dependent on the allometric equation used to estimate AGB. The conclusion is also robust to uncertainty about diameter measurements for problematic trees: for 34 plots in western Amazon forests a significant increase in AGB is found even with a conservative assumption of zero growth for all trees where diameter measurements were made using optical methods and/or growth rates needed to be estimated following fieldwork. Overall, our results suggest a slightly greater rate of net stand–level change than was reported by Phillips et al . Considering the spatial and temporal scale of sampling and associated studies showing increases in forest growth and stem turnover, the results presented here suggest that the total biomass of these plots has on average increased and that there has been a regional–scale carbon sink in old–growth Amazonian forests during the previous two decades.
    Type of Medium: Online Resource
    ISSN: 0962-8436 , 1471-2970
    RVK:
    Language: English
    Publisher: The Royal Society
    Publication Date: 2004
    detail.hit.zdb_id: 1462620-2
    SSG: 12
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  • 3
    Online Resource
    Online Resource
    The Royal Society ; 2004
    In:  Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences Vol. 359, No. 1443 ( 2004-03-29), p. 549-555
    In: Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences, The Royal Society, Vol. 359, No. 1443 ( 2004-03-29), p. 549-555
    Abstract: We present a personal perspective on the highlights of the Theme Issue ‘Tropical forests and global atmospheric change’. We highlight the key findings on the contemporary rate of climatic change in the tropics, the evidence—gained from field studies—of large–scale and rapid change in the dynamics and biomass of old–growth forests, and evidence of how climate change and fragmentation can interact to increase the vulnerability of plants and animals to fires. A range of opinions exists concerning the possible cause of these observed changes, but examination of the spatial ‘fingerprint’ of observed change may help to identify the driving mechanism(s). Studies of changes in tropical forest regions since the last glacial maximum show the sensitivity of species composition and ecology to atmospheric changes. Model studies of change in forest vegetation highlight the potential importance of temperature or drought thresholds that could lead to substantial forest decline in the near future. During the coming century, the Earth's remaining tropical forests face the combined pressures of direct human impacts and a climatic and atmospheric situation not experienced for at least 20 million years. Understanding and monitoring of their response to this atmospheric change are essential if we are to maximize their conservation options.
    Type of Medium: Online Resource
    ISSN: 0962-8436 , 1471-2970
    RVK:
    Language: English
    Publisher: The Royal Society
    Publication Date: 2004
    detail.hit.zdb_id: 1462620-2
    SSG: 12
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  • 4
    Online Resource
    Online Resource
    The Royal Society ; 2004
    In:  Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences Vol. 359, No. 1443 ( 2004-03-29), p. 437-462
    In: Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences, The Royal Society, Vol. 359, No. 1443 ( 2004-03-29), p. 437-462
    Abstract: Recent observations of widespread changes in mature tropical forests such as increasing tree growth, recruitment and mortality rates and increasing above–ground biomass suggest that ‘global change’ agents may be causing predictable changes in tropical forests. However, consensus over both the robustness of these changes and the environmental drivers that may be causing them is yet to emerge. This paper focuses on the second part of this debate. We review (i) the evidence that the physical, chemical and biological environment that tropical trees grow in has been altered over recent decades across large areas of the tropics, and (ii) the theoretical, experimental and observational evidence regarding the most likely effects of each of these changes on tropical forests. Ten potential widespread drivers of environmental change were identified: temperature, precipitation, solar radiation, climatic extremes (including El Niño Southern Oscillation events), atmospheric CO 2 concentrations, nutrient deposition, O 3 /acid depositions, hunting, land–use change and increasing liana numbers. We note that each of these environmental changes is expected to leave a unique ‘fingerprint’ in tropical forests, as drivers directly force different processes, have different distributions in space and time and may affect some forests more than others (e.g. depending on soil fertility). Thus, in the third part of the paper we present testable a priori predictions of forest responses to assist ecologists in attributing particular changes in forests to particular causes across multiple datasets. Finally, we discuss how these drivers may change in the future and the possible consequences for tropical forests.
    Type of Medium: Online Resource
    ISSN: 0962-8436 , 1471-2970
    RVK:
    Language: English
    Publisher: The Royal Society
    Publication Date: 2004
    detail.hit.zdb_id: 1462620-2
    SSG: 12
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  • 5
    Online Resource
    Online Resource
    The Royal Society ; 2004
    In:  Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences Vol. 359, No. 1443 ( 2004-03-29), p. 311-329
    In: Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences, The Royal Society, Vol. 359, No. 1443 ( 2004-03-29), p. 311-329
    Abstract: We present an analysis of the mean climate and climatic trends of tropical rainforest regions over the period 1960–1998, with the aid of explicit maps of forest cover and climatological databases. Until the mid–1970s most regions showed little trend in temperature, and the western Amazon experienced a net cooling probably associated with an interdecadal oscillation. Since the mid–1970s, all tropical rainforest regions have experienced a strong warming at a mean rate of 0.26 ± 0.05 °C per decade, in synchrony with a global rise in temperature that has been attributed to the anthropogenic greenhouse effect. Over the study period, precipitation appears to have declined in tropical rainforest regions at a rate of 1.0 ± 0.8% per decade ( p 〈 5%), declining sharply in northern tropical Africa (at 3–4% per decade), declining marginally in tropical Asia and showing no significant trend in Amazonia. There is no evidence so far of a decline in precipitation in eastern Amazonia, a region thought vulnerable to climate–change–induced drying. The strong drying trend in Africa suggests that this should be a priority study region for understanding the impact of drought on tropical rainforests. We develop and use a dry–season index to study variations in the length and intensity of the dry season. Only African and Indian tropical rainforests appear to have seen a significant increase in dry–season intensity. In terms of interannual variability, the El Niño–Southern Oscillation (ENSO) is the primary driver of temperature variations across the tropics and of precipitation fluctuations for large areas of the Americas and southeast Asia. The relation between ENSO and tropical African precipitation appears less direct.
    Type of Medium: Online Resource
    ISSN: 0962-8436 , 1471-2970
    RVK:
    Language: English
    Publisher: The Royal Society
    Publication Date: 2004
    detail.hit.zdb_id: 1462620-2
    SSG: 12
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  • 6
    In: Biological Reviews, Wiley, Vol. 86, No. 2 ( 2011-05), p. 457-474
    Type of Medium: Online Resource
    ISSN: 1464-7931
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2011
    detail.hit.zdb_id: 1423558-4
    detail.hit.zdb_id: 1476789-2
    SSG: 12
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  • 7
    In: Functional Plant Biology, CSIRO Publishing, Vol. 31, No. 12 ( 2004), p. 1137-
    Abstract: To further our understanding of the influence of global climate change on isoprene production we studied the effect of elevated [CO2] and vapour pressure deficit (VPD) on isoprene emission rates from leaves of Populus deltoides Bartr. during drought stress. Trees, grown inside three large bays with atmospheres containing 430, 800, or 1200 μmol mol–1 CO2 at the Biosphere 2 facility, were subjected to a period of drought during which VPD was manipulated, switching between low VPD (approximately 1 kPa) and high VPD (approximately 3 kPa) for several days. When trees were not water-stressed, elevated [CO2] inhibited isoprene emission and stimulated photosynthesis. Isoprene emission was less responsive to drought than photosynthesis. As water-stress increased, the inhibition of isoprene emission disappeared, probably as a result of stomatal closure and the resulting decreases in intercellular [CO2] (Ci). This assumption was supported by increased isoprene emission under high VPD. Drought and high VPD dramatically increased the proportion of assimilated carbon lost as isoprene. When measured at the same [CO2] , leaves from trees grown at ambient [CO2] always had higher isoprene emission rates than the leaves of trees grown at elevated [CO2] , demonstrating that CO2 inhibition is a long-term effect.
    Type of Medium: Online Resource
    ISSN: 1445-4408
    Language: English
    Publisher: CSIRO Publishing
    Publication Date: 2004
    SSG: 12
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  • 8
    Online Resource
    Online Resource
    The Royal Society ; 2008
    In:  Philosophical Transactions of the Royal Society B: Biological Sciences Vol. 363, No. 1498 ( 2008-05-27), p. 1857-1864
    In: Philosophical Transactions of the Royal Society B: Biological Sciences, The Royal Society, Vol. 363, No. 1498 ( 2008-05-27), p. 1857-1864
    Abstract: Simulations with the Hadley Centre general circulation model (HadCM3), including carbon cycle model and forced by a ‘business-as-usual’ emissions scenario, predict a rapid loss of Amazonian rainforest from the middle of this century onwards. The robustness of this projection to both uncertainty in physical climate drivers and the formulation of the land surface scheme is investigated. We analyse how the modelled vegetation cover in Amazonia responds to (i) uncertainty in the parameters specified in the atmosphere component of HadCM3 and their associated influence on predicted surface climate. We then enhance the land surface description and (ii) implement a multilayer canopy light interception model and compare with the simple ‘big-leaf’ approach used in the original simulations. Finally, (iii) we investigate the effect of changing the method of simulating vegetation dynamics from an area-based model (TRIFFID) to a more complex size- and age-structured approximation of an individual-based model (ecosystem demography). We find that the loss of Amazonian rainforest is robust across the climate uncertainty explored by perturbed physics simulations covering a wide range of global climate sensitivity. The introduction of the refined light interception model leads to an increase in simulated gross plant carbon uptake for the present day, but, with altered respiration, the net effect is a decrease in net primary productivity. However, this does not significantly affect the carbon loss from vegetation and soil as a consequence of future simulated depletion in soil moisture; the Amazon forest is still lost. The introduction of the more sophisticated dynamic vegetation model reduces but does not halt the rate of forest dieback. The potential for human-induced climate change to trigger the loss of Amazon rainforest appears robust within the context of the uncertainties explored in this paper. Some further uncertainties should be explored, particularly with respect to the representation of rooting depth.
    Type of Medium: Online Resource
    ISSN: 0962-8436 , 1471-2970
    RVK:
    Language: English
    Publisher: The Royal Society
    Publication Date: 2008
    detail.hit.zdb_id: 1462620-2
    SSG: 12
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  • 9
    Online Resource
    Online Resource
    The Royal Society ; 2011
    In:  Philosophical Transactions of the Royal Society B: Biological Sciences Vol. 366, No. 1582 ( 2011-11-27), p. 3225-3245
    In: Philosophical Transactions of the Royal Society B: Biological Sciences, The Royal Society, Vol. 366, No. 1582 ( 2011-11-27), p. 3225-3245
    Abstract: The allocation of the net primary productivity (NPP) of an ecosystem between canopy, woody tissue and fine roots is an important descriptor of the functioning of that ecosystem, and an important feature to correctly represent in terrestrial ecosystem models. Here, we collate and analyse a global dataset of NPP allocation in tropical forests, and compare this with the representation of NPP allocation in 13 terrestrial ecosystem models. On average, the data suggest an equal partitioning of allocation between all three main components (mean 34 ± 6% canopy, 39 ± 10% wood, 27 ± 11% fine roots), but there is substantial site-to-site variation in allocation to woody tissue versus allocation to fine roots. Allocation to canopy (leaves, flowers and fruit) shows much less variance. The mean allocation of the ecosystem models is close to the mean of the data, but the spread is much greater, with several models reporting allocation partitioning outside of the spread of the data. Where all main components of NPP cannot be measured, litterfall is a good predictor of overall NPP ( r 2 = 0.83 for linear fit forced through origin), stem growth is a moderate predictor and fine root production a poor predictor. Across sites the major component of variation of allocation is a shifting allocation between wood and fine roots, with allocation to the canopy being a relatively invariant component of total NPP. This suggests the dominant allocation trade-off is a ‘fine root versus wood’ trade-off, as opposed to the expected ‘root–shoot’ trade-off; such a trade-off has recently been posited on theoretical grounds for old-growth forest stands. We conclude by discussing the systematic biases in estimates of allocation introduced by missing NPP components, including herbivory, large leaf litter and root exudates production. These biases have a moderate effect on overall carbon allocation estimates, but are smaller than the observed range in allocation values across sites.
    Type of Medium: Online Resource
    ISSN: 0962-8436 , 1471-2970
    RVK:
    Language: English
    Publisher: The Royal Society
    Publication Date: 2011
    detail.hit.zdb_id: 1462620-2
    SSG: 12
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  • 10
    In: Philosophical Transactions of the Royal Society B: Biological Sciences, The Royal Society, Vol. 373, No. 1760 ( 2018-11-19), p. 20170410-
    Abstract: Meteorological extreme events such as El Niño events are expected to affect tropical forest net primary production (NPP) and woody growth, but there has been no large-scale empirical validation of this expectation. We collected a large high–temporal resolution dataset (for 1–13 years depending upon location) of more than 172 000 stem growth measurements using dendrometer bands from across 14 regions spanning Amazonia, Africa and Borneo in order to test how much month-to-month variation in stand-level woody growth of adult tree stems (NPP stem ) can be explained by seasonal variation and interannual meteorological anomalies. A key finding is that woody growth responds differently to meteorological variation between tropical forests with a dry season (where monthly rainfall is less than 100 mm), and aseasonal wet forests lacking a consistent dry season. In seasonal tropical forests, a high degree of variation in woody growth can be predicted from seasonal variation in temperature, vapour pressure deficit, in addition to anomalies of soil water deficit and shortwave radiation. The variation of aseasonal wet forest woody growth is best predicted by the anomalies of vapour pressure deficit, water deficit and shortwave radiation. In total, we predict the total live woody production of the global tropical forest biome to be 2.16 Pg C yr −1 , with an interannual range 1.96–2.26 Pg C yr −1 between 1996–2016, and with the sharpest declines during the strong El Niño events of 1997/8 and 2015/6. There is high geographical variation in hotspots of El Niño–associated impacts, with weak impacts in Africa, and strongly negative impacts in parts of Southeast Asia and extensive regions across central and eastern Amazonia. Overall, there is high correlation ( r = −0.75) between the annual anomaly of tropical forest woody growth and the annual mean of the El Niño 3.4 index, driven mainly by strong correlations with anomalies of soil water deficit, vapour pressure deficit and shortwave radiation. This article is part of the discussion meeting issue ‘The impact of the 2015/2016 El Niño on the terrestrial tropical carbon cycle: patterns, mechanisms and implications’.
    Type of Medium: Online Resource
    ISSN: 0962-8436 , 1471-2970
    RVK:
    Language: English
    Publisher: The Royal Society
    Publication Date: 2018
    detail.hit.zdb_id: 1462620-2
    SSG: 12
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