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  • 1
    Online Resource
    Online Resource
    Pattern and process in Amazon tree turnover, 1976–2001
    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. 381-407
    Details
    In: Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences, The Royal Society, Vol. 359, No. 1443 ( 2004-03-29), p. 381-407
    Abstract: Previous work has shown that tree turnover, tree biomass and large liana densities have increased in mature tropical forest plots in the late twentieth century. These results point to a concerted shift in forest ecological processes that may already be having significant impacts on terrestrial carbon stocks, fluxes and biodiversity. However, the findings have proved controversial, partly because a rather limited number of permanent plots have been monitored for rather short periods. The aim of this paper is to characterize regional–scale patterns of ‘tree turnover’ (the rate with which trees die and recruit into a population) by using improved datasets now available for Amazonia that span the past 25 years. Specifically, we assess whether concerted changes in turnover are occurring, and if so whether they are general throughout the Amazon or restricted to one region or environmental zone. In addition, we ask whether they are driven by changes in recruitment, mortality or both. We find that: (i) trees 10 cm or more in diameter recruit and die twice as fast on the richer soils of southern and western Amazonia than on the poorer soils of eastern and central Amazonia; (ii) turnover rates have increased throughout Amazonia over the past two decades; (iii) mortality and recruitment rates have both increased significantly in every region and environmental zone, with the exception of mortality in eastern Amazonia; (iv) recruitment rates have consistently exceeded mortality rates; (v) absolute increases in recruitment and mortality rates are greatest in western Amazonian sites; and (vi) mortality appears to be lagging recruitment at regional scales. These spatial patterns and temporal trends are not caused by obvious artefacts in the data or the analyses. The trends cannot be directly driven by a mortality driver (such as increased drought or fragmentation–related death) because the biomass in these forests has simultaneously increased. Our findings therefore indicate that long–acting and widespread environmental changes are stimulating the growth and productivity of Amazon forests.
    Type of Medium: Online Resource
    ISSN: 0962-8436 , 1471-2970
    URL: Article
    DOI: 10.1098/rstb.2003.1438
    RVK:
    WA 15000
    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
    Concerted changes in tropical forest structure and dynamics: evidence from 50 South American long-term plots
    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. 421-436
    Details
    In: Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences, The Royal Society, Vol. 359, No. 1443 ( 2004-03-29), p. 421-436
    Abstract: Several widespread changes in the ecology of old–growth tropical forests have recently been documented for the late twentieth century, in particular an increase in stem turnover (pan–tropical), and an increase in above–ground biomass (neotropical). Whether these changes are synchronous and whether changes in growth are also occurring is not known. We analysed stand–level changes within 50 long–term monitoring plots from across South America spanning 1971–2002. We show that: (i) basal area (BA: sum of the cross–sectional areas of all trees in a plot) increased significantly over time (by 0.10 ±; 0.04 m 2 ha −1 yr −1 , mean ± 95%CI) as did both (ii) stand–level BA growth rates (sum of the increments of BA of surviving trees and BA of new trees that recruited into a plot); and (iii) stand–level BA mortality rates (sum of the cross–sectional areas of all trees that died in a plot). Similar patterns were observed on a per–stem basis: (i) stem density (number of stems per hectare; 1 hectare is 10 4 m 2 ) increased significantly over time ( 0.94 ± 0.63 stems ha −1 yr −1 ); as did both (ii) stem recruitment rates; and (iii) stem mortality rates. In relative terms, the pools of BA and stem density increased by 0.38 ± 0.15% and 0.18 ± 0.12% yr −1 , respectively. The fluxes into and out of these pools—stand–level BA growth, stand–level BA mortality, stem recruitment and stem mortality rates—increased, in relative terms, by an order of magnitude more. The gain terms (BA growth, stem recruitment) consistently exceeded the loss terms (BA loss, stem mortality) throughout the period, suggesting that whatever process is driving these changes was already acting before the plot network was established. Large long–term increases in stand–level BA growth and simultaneous increases in stand BA and stem density imply a continent–wide increase in resource availability which is increasing net primary productivity and altering forest dynamics. Continent–wide changes in incoming solar radiation, and increases in atmospheric concentrations of CO 2 and air temperatures may have increased resource supply over recent decades, thus causing accelerated growth and increased dynamism across the world's largest tract of tropical forest.
    Type of Medium: Online Resource
    ISSN: 0962-8436 , 1471-2970
    URL: Article
    DOI: 10.1098/rstb.2003.1431
    RVK:
    WA 15000
    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
    Increasing biomass in Amazonian forest plots
    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
    Details
    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
    URL: Article
    DOI: 10.1098/rstb.2003.1422
    RVK:
    WA 15000
    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
    Tropical forests and global atmospheric change: a synthesis
    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
    Details
    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
    URL: Article
    DOI: 10.1098/rstb.2003.1449
    RVK:
    WA 15000
    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
    Fingerprinting the impacts of global change on tropical forests
    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
    Details
    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
    URL: Article
    DOI: 10.1098/rstb.2003.1432
    RVK:
    WA 15000
    Language: English
    Publisher: The Royal Society
    Publication Date: 2004
    detail.hit.zdb_id: 1462620-2
    SSG: 12
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  • 6
    Online Resource
    Online Resource
    Spatial patterns and recent trends in the climate of tropical rainforest regions
    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
    Details
    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
    URL: Article
    DOI: 10.1098/rstb.2003.1433
    RVK:
    WA 15000
    Language: English
    Publisher: The Royal Society
    Publication Date: 2004
    detail.hit.zdb_id: 1462620-2
    SSG: 12
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  • 7
    Online Resource
    Online Resource
    Local spatial structure of forest biomass and its consequences for remote sensing of carbon stocks
    Copernicus GmbH ; 2014
    In:  Biogeosciences Vol. 11, No. 23 ( 2014-12-08), p. 6827-6840
    Details
    In: Biogeosciences, Copernicus GmbH, Vol. 11, No. 23 ( 2014-12-08), p. 6827-6840
    Abstract: Abstract. Advances in forest carbon mapping have the potential to greatly reduce uncertainties in the global carbon budget and to facilitate effective emissions mitigation strategies such as REDD+ (Reducing Emissions from Deforestation and Forest Degradation). Though broad-scale mapping is based primarily on remote sensing data, the accuracy of resulting forest carbon stock estimates depends critically on the quality of field measurements and calibration procedures. The mismatch in spatial scales between field inventory plots and larger pixels of current and planned remote sensing products for forest biomass mapping is of particular concern, as it has the potential to introduce errors, especially if forest biomass shows strong local spatial variation. Here, we used 30 large (8–50 ha) globally distributed permanent forest plots to quantify the spatial variability in aboveground biomass density (AGBD in Mg ha–1) at spatial scales ranging from 5 to 250 m (0.025–6.25 ha), and to evaluate the implications of this variability for calibrating remote sensing products using simulated remote sensing footprints. We found that local spatial variability in AGBD is large for standard plot sizes, averaging 46.3% for replicate 0.1 ha subplots within a single large plot, and 16.6% for 1 ha subplots. AGBD showed weak spatial autocorrelation at distances of 20–400 m, with autocorrelation higher in sites with higher topographic variability and statistically significant in half of the sites. We further show that when field calibration plots are smaller than the remote sensing pixels, the high local spatial variability in AGBD leads to a substantial "dilution" bias in calibration parameters, a bias that cannot be removed with standard statistical methods. Our results suggest that topography should be explicitly accounted for in future sampling strategies and that much care must be taken in designing calibration schemes if remote sensing of forest carbon is to achieve its promise.
    Type of Medium: Online Resource
    ISSN: 1726-4189
    URL: Article
    URL: Article
    DOI: 10.5194/bg-11-6827-2014
    DOI: 10.5194/bg-11-6827-2014-supplement
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2014
    detail.hit.zdb_id: 2158181-2
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  • 8
    Online Resource
    Online Resource
    Influence of landscape heterogeneity on spatial patterns of wood productivity, wood specific density and above ground biomass in Amazonia
    Copernicus GmbH ; 2009
    In:  Biogeosciences Vol. 6, No. 9 ( 2009-09-08), p. 1883-1902
    Details
    In: Biogeosciences, Copernicus GmbH, Vol. 6, No. 9 ( 2009-09-08), p. 1883-1902
    Abstract: Abstract. Long-term studies using the RAINFOR network of forest plots have generated significant insights into the spatial and temporal dynamics of forest carbon cycling in Amazonia. In this work, we map and explore the landscape context of several major RAINFOR plot clusters using Landsat ETM+ satellite data. In particular, we explore how representative the plots are of their landscape context, and test whether bias in plot location within landscapes may be influencing the regional mean values obtained for important forest biophysical parameters. Specifically, we evaluate whether the regional variations in wood productivity, wood specific density and above ground biomass derived from the RAINFOR network could be driven by systematic and unintentional biases in plot location. Remote sensing data covering 45 field plots were aggregated to generate landscape maps to identify the specific physiognomy of the plots. In the Landsat ETM+ data, it was possible to spectrally differentiate three types of terra firme forest, three types of forests over Paleovarzea geomorphologycal formation, two types of bamboo-dominated forest, palm forest, Heliconia monodominant vegetation, swamp forest, disturbed forests and land use areas. Overall, the plots were generally representative of the forest physiognomies in the landscape in which they are located. Furthermore, the analysis supports the observed regional trends in those important forest parameters. This study demonstrates the utility of landscape scale analysis of forest physiognomies for validating and supporting the finds of plot based studies. Moreover, the more precise geolocation of many key RAINFOR plot clusters achieved during this research provides important contextual information for studies employing the RAINFOR database.
    Type of Medium: Online Resource
    ISSN: 1726-4189
    URL: Article
    DOI: 10.5194/bg-6-1883-2009
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2009
    detail.hit.zdb_id: 2158181-2
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  • 9
    Online Resource
    Online Resource
    Regional and seasonal patterns of litterfall in tropical South America
    Copernicus GmbH ; 2010
    In:  Biogeosciences Vol. 7, No. 1 ( 2010-01-05), p. 43-55
    Details
    In: Biogeosciences, Copernicus GmbH, Vol. 7, No. 1 ( 2010-01-05), p. 43-55
    Abstract: Abstract. The production of aboveground soft tissue represents an important share of total net primary production in tropical rain forests. Here we draw from a large number of published and unpublished datasets (n=81 sites) to assess the determinants of litterfall variation across South American tropical forests. We show that across old-growth tropical rainforests, litterfall averages 8.61±1.91 Mg ha−1 yr−1 (mean ± standard deviation, in dry mass units). Secondary forests have a lower annual litterfall than old-growth tropical forests with a mean of 8.01±3.41 Mg ha−1 yr−1. Annual litterfall shows no significant variation with total annual rainfall, either globally or within forest types. It does not vary consistently with soil type, except in the poorest soils (white sand soils), where litterfall is significantly lower than in other soil types (5.42±1.91 Mg ha−1 yr−1). We also study the determinants of litterfall seasonality, and find that it does not depend on annual rainfall or on soil type. However, litterfall seasonality is significantly positively correlated with rainfall seasonality. Finally, we assess how much carbon is stored in reproductive organs relative to photosynthetic organs. Mean leaf fall is 5.74±1.83 Mg ha−1 yr−1 (71% of total litterfall). Mean allocation into reproductive organs is 0.69±0.40 Mg ha−1 yr−1 (9% of total litterfall). The investment into reproductive organs divided by leaf litterfall increases with soil fertility, suggesting that on poor soils, the allocation to photosynthetic organs is prioritized over that to reproduction. Finally, we discuss the ecological and biogeochemical implications of these results.
    Type of Medium: Online Resource
    ISSN: 1726-4189
    URL: Article
    DOI: 10.5194/bg-7-43-2010
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2010
    detail.hit.zdb_id: 2158181-2
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  • 10
    Online Resource
    Online Resource
    Patterns of nitrogen‐fixing tree abundance in forests across Asia and America
    Wiley ; 2019
    In:  Journal of Ecology Vol. 107, No. 6 ( 2019-11), p. 2598-2610
    Details
    In: Journal of Ecology, Wiley, Vol. 107, No. 6 ( 2019-11), p. 2598-2610
    Abstract: Symbiotic nitrogen (N)‐fixing trees can provide large quantities of new N to ecosystems, but only if they are sufficiently abundant. The overall abundance and latitudinal abundance distributions of N‐fixing trees are well characterised in the Americas, but less well outside the Americas. Here, we characterised the abundance of N‐fixing trees in a network of forest plots spanning five continents, ~5,000 tree species and ~4 million trees. The majority of the plots (86%) were in America or Asia. In addition, we examined whether the observed pattern of abundance of N‐fixing trees was correlated with mean annual temperature and precipitation. Outside the tropics, N‐fixing trees were consistently rare in the forest plots we examined. Within the tropics, N‐fixing trees were abundant in American but not Asian forest plots (~7% versus ~1% of basal area and stems). This disparity was not explained by mean annual temperature or precipitation. Our finding of low N‐fixing tree abundance in the Asian tropics casts some doubt on recent high estimates of N fixation rates in this region, which do not account for disparities in N‐fixing tree abundance between the Asian and American tropics. Synthesis . Inputs of nitrogen to forests depend on symbiotic nitrogen fixation, which is constrained by the abundance of N‐fixing trees. By analysing a large dataset of ~4 million trees, we found that N‐fixing trees were consistently rare in the Asian tropics as well as across higher latitudes in Asia, America and Europe. The rarity of N‐fixing trees in the Asian tropics compared with the American tropics might stem from lower intrinsic N limitation in Asian tropical forests, although direct support for any mechanism is lacking. The paucity of N‐fixing trees throughout Asian forests suggests that N inputs to the Asian tropics might be lower than previously thought.
    Type of Medium: Online Resource
    ISSN: 0022-0477 , 1365-2745
    URL: Issue
    URL: Article
    DOI: 10.1111/jec.v107.6
    DOI: 10.1111/1365-2745.13199
    Language: English
    Publisher: Wiley
    Publication Date: 2019
    detail.hit.zdb_id: 3023-5
    detail.hit.zdb_id: 2004136-6
    SSG: 12
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