This article was downloaded by: [Queensland University of Technology] On: 10 April 2014, At: 21:40 Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK Plant Ecology & Diversity Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/tped20 Shifting dynamics of climate-functional groups in old- growth Amazonian forests Nathalie Butt a g , Yadvinder Malhi a , Mark New a h i , Manuel J. Macía b , Simon L. Lewis c d , Gabriela Lopez-Gonzalez c , William F. Laurance e , Susan Laurance e , Regina Luizão f , Ana Andrade f , Timothy R. Baker c , Samuel Almeida j & Oliver L. Phillips c a Oxford University School of Geography and the Environment , Oxford , UK b Departamento de Biología , Área de Botánica, Universidad Autónoma de Madrid , Spain c Earth and Biosphere Institute, School of Geography, University of Leeds , UK d Department of Geography , University College London , London , UK e James Cook University , Cairns , Australia f INPA , Manaus , Brazil g School of Biological Sciences , University of Queensland , Brisbane , Australia h African Climate and Development Initiative i Department of Environmental and Geographical Science , University of Capetown , South Africa; Died 2011 j Died 2011 Accepted author version posted online: 30 Jul 2012.Published online: 02 Oct 2012. To cite this article: Nathalie Butt , Yadvinder Malhi , Mark New , Manuel J. Macía , Simon L. Lewis , Gabriela Lopez- Gonzalez , William F. Laurance , Susan Laurance , Regina Luizão , Ana Andrade , Timothy R. Baker , Samuel Almeida & Oliver L. Phillips (2014) Shifting dynamics of climate-functional groups in old-growth Amazonian forests, Plant Ecology & Diversity, 7:1-2, 267-279, DOI: 10.1080/17550874.2012.715210 To link to this article: http://dx.doi.org/10.1080/17550874.2012.715210 PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions Plant Ecology & Diversity, 2014 Vol. 7, Issues 1–2, 267–279, http://dx.doi.org/10.1080/17550874.2012.715210 Shifting dynamics of climate-functional groups in old-growth Amazonian forests Nathalie Butta,g*, Yadvinder Malhia , Mark Newa,h,i , Manuel J. Macíab , Simon L. Lewisc,d , Gabriela Lopez-Gonzalezc , William F. Laurancee , Susan Laurancee , Regina Luizãof , Ana Andradef , Timothy R. Bakerc , Samuel Almeida+ and Oliver L. Phillipsc aOxford University School of Geography and the Environment, Oxford, UK; bDepartamento de Biología, Área de Botánica, Universidad Autónoma de Madrid, Spain; cEarth and Biosphere Institute, School of Geography, University of Leeds, UK; dDepartment of Geography, University College London, London, UK; eJames Cook University, Cairns, Australia; fINPA, Manaus, Brazil; gSchool of Biological Sciences, University of Queensland, Brisbane, Australia; hAfrican Climate and Development Initiative; iDepartment of Environmental and Geographical Science, University of Capetown, South Africa; +Died 2011 (Received 1 February 2012; final version received 20 July 2012) Background: Climate change is driving ecosystem shifts, which has implications for tropical forest system function and productivity. Aim: To investigate Amazon forest dynamics and test for compositional changes between 1985 and 2005 across different plant groups. Methods: Tree census data from 46 long-term RAINFOR forest plots in Amazonia for three climate-functional groups were used: dry-affiliate, climate-generalist and wet affiliate. Membership of each group was ascribed at genus level from the dis- tribution of individuals across a wet–dry gradient in Amazonia, and then used to determine whether the proportions of these functional groups have changed over time, and the direction of any change. Results: In total, 91 genera, representing 59% of the stems and 18% of genera in the plots, were analysed. Wet-affiliates tended to move from a state of net basal area gain towards dynamic equilibrium, defined as where gain ≈ loss, governed by an increase in loss rather than a decrease in growth and mainly driven by plots in north-west Amazonia, the wettest part of the region. Dry-affiliates remained in a state of strong net basal area gain across western Amazonia and showed a strong increase in stem recruitment. Wet-affiliates and climate-generalists showed increases in stem mortality, and climate-generalists showed increased stem recruitment, resulting in overall equilibrium of stem numbers. Conclusions: While there were no significant shifts in most genera, the results suggest an overall shift in climate-func- tional forest composition in western Amazonia away from wet-affiliates, and potential for increased forest persistence under projected drier conditions in the future. Keywords: climate trends; forest composition; moisture affiliation; moisture seasonality; tropical forest Introduction A number of studies worldwide have shown that climate change elicits forest ecosystem responses such as changes in phenology, forest composition and productivity (Nemani et al. 2003; Parmesan and Yohe 2003; IPCC 2007). The tropics host the most diverse and productive forest sys- tems on Earth (Beer et al. 2010) yet, until the end of the twentieth century, they were relatively poorly studied, for reasons of remoteness and inaccessibility. While research on the impacts of climate change has typically focused elsewhere, changes in ecosystem structure and function are also very likely to be occurring in the tropics where climate-driven changes may affect the role forests play as carbon sinks (Lewis et al. 2004a, 2009). Analysis of long-term Amazon plot data, part of the RAINFOR project (Malhi et al. 2002), has shown that old growth forests have increased in biomass in recent years (Baker et al. 2004), and that Amazonian forests generally have become more, pro- ductive and dynamic in terms of rates of stem recruitment, mortality and turnover (Phillips et al. 1998, 2004; Baker et al. 2004; Lewis et al. 2004b). Such changes in structure *Corresponding author. Email: n.butt@uq.edu.au have included an Amazon-wide increase in stem recruit- ment and mortality (Phillips et al. 2004), and a Neotropical increase in above-ground woody biomass (Phillips et al. 1998, 2002; Baker et al. 2004), albeit perhaps temporar- ily reversed by an intense drought in 2005 (Phillips et al. 2009). There have been few studies of trends in func- tional composition in old-growth tropical forests, although Phillips et al. (2002) have shown that large lianas in intact western Amazon forests have recently increased in relative dominance, a pattern that may extend across the Neotropics (Wright et al. 2004; Schnitzer and Bongers 2011) and Laurance et al. (2004) found increasing rates of growth in most relatively abundant tree genera in a central Amazonian landscape, and a general increase in rates of tree mortal- ity and recruitment. The results suggested that numbers of faster-growing old-growth genera (primarily canopy trees) increased, while slower-growing understory genera decreased. Pan-tropical analyses by Chave et al. (2008) and Lewis et al. (2009) also showed a significant increase in biomass across 10 and 156 forest plots respectively. © 2012 Botanical Society of Scotland and Taylor & Francis D ow nl oa de d by [Q ue en sla nd U niv ers ity of T ec hn olo gy ] a t 2 1:4 0 1 0 A pri l 2 01 4 268 N. Butt et al. Changes in climate variables such as temperature, pre- cipitation, solar radiation and diffuse fraction of solar radi- ation, more important for sub-canopy species (cf. Nemani et al. 2003), are possible drivers of this observed accel- erated growth, as is the increase of atmospheric CO2 concentration (Curtis and Wang 1998; Norby et al. 1999; Cramer et al. 2001). While water use efficiency (WUE) is predicted to increase with rising atmospheric CO2 con- centrations (Farquhar 1997; Winter et al. 2001), rising temperatures may increase transpiration rates and water stress (Malhi et al. 2009), and across the region there was a long-term trend of temperature increase of 0.26 ◦C decade−1 (Malhi and Wright 2004). With plant moisture availability the strongest of several environmental and bio- physical variables in terms of forest structure (Toledo et al. 2011a), precipitation seasonality is an important factor in plant species richness and diversity and the composition of plant assemblages (Gentry 1988; ter Steege et al. 2003; Butt et al. 2008). Although changes in interannual and seasonal precipitation amounts were insignificant across the region overall (Malhi and Wright 2004), there has been a trend of increasing dry season length (Marengo et al. 2011), a significant decrease in dry season cloud fraction and cloud- related diffuse radiation, of about 8% (Butt et al. 2009), and an increasing trend of incoming short-wave solar radiation (Hashimoto et al. 2010). While it has not been estab- lished whether other climatic or environmental variables may be influencing tropical biodiversity and productivity, these three factors may act to increase seasonal water stress even in the absence of changes in the rainfall regime. From the perspective of plot dynamics, this paper sets out to investigate temporal trends in forest community com- position across Amazonian old-growth forests utilising a large and unique database. While earlier studies examined shifts in species in relation to drought (Condit 1998; Enquist and Enquist 2011; Feeley et al. 2011), they were focussed on single sites or smaller areas; possible trends in relation to water availability have not been previously investigated across a large number of sites. The aim of the work is to establish if there have been any shifts or trends in proportions and dynamics of wet-affiliate, dry-affiliate and climate-generalist tree genera on a decadal level, and to quantify the magnitude of any change. Moisture affiliation is related to drought and shade tolerance, and productivity is a function of the potential trade-off between drought tol- erance and growth, which may also be determined by CO2 concentration. We therefore expect that, in response to envi- ronmental trends: 1) increasing seasonality would favour more drought-tolerant plant groups; and that 2) increasing ambient CO2 concentrations might favour more drought- sensitive plant groups by improving water use efficiency. Materials and methods Floristic data Floristic data were extracted from the RAINFOR database (www.forestplots.net; Lopez-Gonzalez et al. 2011) in November 2006. The RAINFOR census plots are located across the Amazon region and the data vary greatly in temporal range. Measurement details and methodology have been previously described (e.g. Phillips et al. 2002). For this analysis we selected plot censuses which spanned at least 10 years, with at least two census intervals. In total, 46 plots below 1000 m a.s.l. were used in the analysis. The plots were allocated to one of three regions: south-west and north-west, at either end of the north–south moisture gradient (north→south = wetter→drier) across western Amazonia, and east-central Amazonia (Figure 1), which are characterised by different climates. Mean monthly Figure 1. Distribution of the RAINFOR census plots in Amazonia used in this analysis. D ow nl oa de d by [Q ue en sla nd U niv ers ity of T ec hn olo gy ] a t 2 1:4 0 1 0 A pri l 2 01 4 Compositional shifts in lowland Amazon forests 269 dry quarter rainfall over the period covering the census monthly data (1985–2005), was 202 mm for the north-west region, 74 mm for the east-central region and 36 mm for the south-west (University of Delaware (UDEL) and Climate Research Unit, University of East Anglia (CRU) long-term data). As the temporal range of the plot censuses varied so greatly, the investigation focused on the 20-year period from 1985 until 2005, ending immediately prior to the Amazon drought of 2005 (Phillips et al. 2009). Overall, 24 plots had 15 or more years of census data. The num- ber of plots per region was as follows: for the east-central region, n = 17; for the north-west region, n = 11, and for the south-west region, n = 18. Plot details are given in Appendix 1. Climate functional groups We previously investigated generic affiliations with the pre- cipitation gradient in western Amazonia (Butt et al. 2008), quantifying the relationship between moisture seasonality and plant abundance for nearly 100 common woody plant genera using all woody stems ≥ 2.5 cm dbh in 39 plots (0.1 ha) below 1000 m elevation (lowland), and west of 62◦ W, of the Gentry sample plot dataset (http://www. salvias.net/pages/index.html) (Appendix 2). Of the 91 gen- era analysed, there were significant correlations for a third of the genera with either wetter (designated as ‘wet-affiliates’) or drier conditions (designated as ‘dry- affiliates’), and two-thirds, with no moisture seasonality affiliation, were designated as ‘climate-generalists’. In the current analysis, the climate functional groups represent about 60% of individuals and 18% of genera in the plots analysed. Here we use data for stems ≥ 10 cm dbh from the RAINFOR dataset and first divide the genera into the three climate functional groups; the remainder (those genera not previously tested) were grouped as ‘unknown’ (430 gen- era). Relative abundances were calculated using the data for all stems, including the ‘unknown’ group as well as the three functional groups. We used plots with at least two census intervals and standardised the dataset to analyse three censuses with two census intervals of about the same length to avoid possible census interval effects confounding the results. The average date of the first, mid and final censuses was 1988, 1994 and 2003. The first census interval, on average, was 6.4 ± 1.9 years (standard deviation; range 4–11 years); the second was 8.1 ± 2.5 years (range 4–13 years). The regions varied from each other only slightly in this respect, with a first census interval of 5.9 years for the north-west, 6.1 years for the south-west, and 7.1 years for east-central. The second census interval was 8.5 years for the north-west and east- central regions, and 7.6 years for the south-west region. The mean plot size was 1.4 ± 0.2 ha (range 0.4–9 ha). We examined net changes, between ∼1985 and ∼2005, for each of the three climate functional groups (wet-affiliate, climate-generalists and dry-affiliates). We calculated basal area (BA) and stem density at each cen- sus, BA growth and mortality rates, and stem recruitment and mortality rates, for both census intervals, and used Wilcoxon two-sample tests (as the rates were not normally distributed) to establish the significance of the differences over time. The calculations were as follows (cf. Lewis et al. 2004b): Mortality λ = [ln n0 − ln(n0 − Dt)] /t 1 λ × 100 gives percent per annum, where λ is the mortality coefficient, n0 is the total BA or number of stems at the start of the interval, Dt is the BA or stem loss during the interval, and t is the interval (in years). Recruitment μ = [ln nt − ln(n0 − Dt)] /t 2 ln nt is the value for BA or stems at the end of the inter- val. These calculations allowed us to compare mortality and growth/recruitment for BA and stem density across the cli- mate functional groups, overall, and by region. We used a log-linear analysis in order to retain normal distributions in the analysis. We assessed whether the climate functional groups, overall and by region, are in (or close to) dynamic equi- librium, defined as where the level of gain is similar to that of loss, and examine changes between intervals. We determined these measures for all woody plants overall, by climate functional group, and by region, and considered whether the changes over time were driven by mortality or growth. Within a plot, changes in BA correlate strongly with changes in biomass (Malhi et al. 2006), and hence the BA dynamics can be taken to be broadly indicative of changes in biomass dynamics, neglecting net changes in tree allometry and wood density. Results Distribution and abundance of the climate functional groups The ‘dry’ group (four genera) was present in 41 of the 46 plots at the beginning of the period of study. The plots where it was not present were primarily in the north- west, the wettest Amazonian region. The ‘wet’ (27 genera) and ‘generalist’ (60 genera) groups were present in all plots. The dominant genera in the wet-affiliate group were: Eschweilera and Protium (>15% each of classified wet- affiliate stems); Pouteria and Iriartea each contributed more than 10% of stems to the generalist group; in the dry-affiliate group Aspidosperma overwhelmingly domi- nated, with around 90% of classified stems. The relative abundance, in terms of proportional BA and individuals, of the three climate functional groups varied by region with the climate-generalists dominating in the south-west region and the wet-affiliates dominating in the north-west and east-central regions (Table 1). In terms of stem numbers, but not BA, the dry-affiliates were more abundant in the south-west and east-central D ow nl oa de d by [Q ue en sla nd U niv ers ity of T ec hn olo gy ] a t 2 1:4 0 1 0 A pri l 2 01 4 270 N. Butt et al. Table 1(a). Relative abundance (%) by region, by climate func- tional group as a proportion of all stems, including the ‘unknown’ group. Climate functional group Wet Generalist Dry Unknown South-west % BA 12 41 1 45 % stems 17 48 1 34 East-central % BA 26 19 2 52 % stems 35 24 1 40 North-west % BA 30 24 2 43 % stems 32 28 0.3 39 Table 1(b). Absolute stem numbers by region and by climate functional group, including the ‘unknown’ group. Wet Generalist Dry Unknown All regions Census 1 9684 11589 237 13456 Census 2 9689 11674 231 13415 Census 3 9411 11537 235 14386 South-west Census 1 2150 6206 127 4551 Census 2 2144 6372 122 4494 Census 3 2113 6505 128 4648 East-central Census 1 6008 4081 94 7035 Census 2 5962 3999 93 7071 Census 3 5682 3778 90 7816 North-west Census 1 1526 1302 16 1870 Census 2 1583 1303 16 1850 Census 3 1616 1254 17 1922 regions, more than twice as abundant as in the north-west. However, the dry-affiliate group as defined in our analysis comprised less than 2% of stems or BA in any of the regions (Table 1(a), and Table 1(b) for absolute stem numbers). Temporal trends in climate functional group growth and mortality We present statistically significant results in the figures, and all results in Table 2 (Wilcoxon analyses at P <0.05). Overall, there was a clear relationship between climate functional group and dynamism, with wet-affiliates being the most dynamic, and dry-affiliates the least dynamic. In terms of net changes between intervals, wet-affiliates moved from experiencing strong net gain in BA in the first interval towards dynamic equilibrium (not significantly dif- ferent from the one-one line), in the second as BA loss rates increased. Wet-affiliates maintained high dynamism over- all (Figure 2(a)). Climate-generalists maintained a slight net BA gain while dry-affiliates remained in a strong dynamic disequilibrium (significantly different from the one-one line) of net BA gain. Analysis of stem dynamics by climate functional group indicates that the wet-affiliate and climate-generalist groups showed increases in stem mortality (P < 0.05, z1.645 P = 0.2, z0.842 respectively) (Figure 2(b)), and both groups shifted slightly away from dynamic equilibrium (from P = 0.7, z−0.524 to P < 0.05, z1.645 for wet-affiliates; P = 0.5, z−0.01 to P < 0.05, z1.645 for climate-generalists): the first interval was not significantly different from dynamic equilibrium. Dry- affiliates, the least dynamic group of the three, showed a strong increase in recruitment and weaker decrease in mor- tality (P < 0.08, z1.405, P = 0.7, z−0.524 respectively), and moved from a state of net stem loss to net stem gain. Temporal trends in climate functional group growth and mortality by region All groups in the north-west plots gained in BA in the first interval (Table 2, Figure 3(a)). Wet-affiliates and climate- generalists all showed a significant (P < 0.05, z1.645 and P < 0.01, z2.326) increase in BA loss, and climate- generalists also showed a significant increase in BA gain (P < 0.05, z1.645). The most marked change was that wet- affiliate and climate-generalist groups showed a significant increase in stem mortality (P < 0.05, z1.645 and P < 0.01, z2.326, respectively), causing an overall increase in stem mortality (P < 0.05, z1.645) (Table 2, Figure 3(b)). Dry-affiliates showed a significant increase in stem recruitment in the south-west (P < 0.01, z2.326) and moved from net stem loss to net stem gain (Figure 4). This large increase in dry-affiliate stem recruitment was not driven by one plot but is seen in most plots. There was no significant change in dry-affiliate BA. As the dry-affiliate group is dominated by a single genus Aspidosperma (∼90% of all dry-affiliate individ- uals), analyses were performed to investigate whether this genus alone was driving the dynamics of the dry- affiliate group. There were 24 species of Aspidosperma distributed across the plot network in the north-west and south-west, which indicates a potentially high level of intra-generic ecophysiological variability. For the north- west plots, Aspidosperma was the sole driver of changes in stem mortality (and thus BA loss) and stem recruit- ment in the dry-affiliate group. However, there was a larger difference (increase) in BA gain between the two cen- sus intervals when Aspidosperma was excluded from the analysis, i.e. the increase in growth over time was more pronounced in the other dry genera than in Aspidosperma (Figure 5(a)). In the other region where dry-affiliates other than Aspidosperma were recorded, the south-west, BA gain and stem recruitment were both higher between intervals when Aspidosperma was excluded, while stem mortality increased rather than decreased (but not sig- nificantly) (Figure 5(b) and Table 3). Hence exclusion of Aspidosperma enhances the trends in the dry-affiliates rather than suppressing them. Further investigation of the other dry-affiliates indicated that the trends reported over- all for dry-affiliates were consistent across plots and genera: no single genus or plot was driving the results. D ow nl oa de d by [Q ue en sla nd U niv ers ity of T ec hn olo gy ] a t 2 1:4 0 1 0 A pri l 2 01 4 Compositional shifts in lowland Amazon forests 271 Table 2. Mean and standard error values for plant climate functional group basal area loss and growth and stem mortality and recruit- ment, for all groups and all regions, for the two intervals. Significant changes between interval highlighted; ∗, P < 0.05; ∗∗, P < 0.01 significant change (Wilcoxon test statistic). Basal area loss Std error Basal area growth Std error Wet affiliate Interval 1 Interval 2 Interval 1 Interval 2 Interval 1 Interval 2 Interval 1 Interval 2 North-west ∗1.66 ∗3.28 0.28 0.43 2.69 2.93 0.21 0.16 East-central 1.46 1.37 0.36 0.13 1.41 1.55 0.1 0.07 South-west 2.62 2.76 0.41 0.34 3.04 2.93 0.15 0.19 Stem mortality Std error Stem recruitment Std error Wet affiliate Interval 1 Interval 2 Interval 1 Interval 2 Interval 1 Interval 2 Interval 1 Interval 2 North-west ∗1.61 ∗2.44 0.24 0.22 2.22 2.48 0.31 0.34 East-central 1.57 1.32 0.34 0.09 1.23 0.77 0.17 0.13 South-west 2.61 2.73 0.28 0.23 2.59 2.48 0.23 0.3 Basal area loss Std error Basal area growth Std error Climate generalist Interval 1 Interval 2 Interval 1 Interval 2 Interval 1 Interval 2 Interval 1 Interval 2 North-west ∗∗1.66 ∗∗3.05 0.39 0.28 ∗2.40 ∗2.95 0.2 0.32 East-central 1.86 1.32 0.39 0.17 1.43 1.52 0.09 0.13 South-west 2.18 2.11 0.29 0.16 2.41 2.48 0.13 0.14 Stem mortality Std error Stem recruitment Std error Climate generalist Interval 1 Interval 2 Interval 1 Interval 2 Interval 1 Interval 2 Interval 1 Interval 2 North-west ∗∗1.87 ∗∗2.85 0.21 0.22 ∗1.81 ∗2.40 0.24 0.23 East-central 1.77 1.38 0.37 0.11 1.08 0.83 0.15 0.17 South-west 1.83 2.11 0.1 0.11 2.15 2.18 0.23 0.19 Basal area loss Std error Basal area growth Std error Dry affiliate Interval 1 Interval 2 Interval 1 Interval 2 Interval 1 Interval 2 Interval 1 Interval 2 North-west 0.02 0.01 0.02 0.01 1.4 2.22 0.43 0.58 East-central 0.69 1.11 0.4 0.74 0.97 1.12 0.16 0.22 South-west 0.94 1.06 0.62 0.52 1.77 1.97 0.37 0.41 Stem mortality Std error Stem recruitment Std error Dry affiliate Interval 1 Interval 2 Interval 1 Interval 2 Interval 1 Interval 2 Interval 1 Interval 2 North-west 0.6 0.4 0.6 0.4 0.6 0.47 0.6 0.47 East-central 1.07 0.53 0.69 0.1 0.68 0.16 0.4 0.1 South-west 1.51 0.44 0.26 0.98 ∗0.44 ∗2.29 0.26 0.65 Discussion Our analysis demonstrates the forest change that occurred in Amazonia between 1985 and 2005: wet affiliates showed a relative decrease in both BA and stem number overall, while generalists and dry affiliates showed relative increases in these two metrics. Recent findings from an analysis of species composition in plots in Costa Rica, on Barro Colorado Island, and across a Panama-wide precipitation gradient, also indicated an increase in the rep- resentation of drought-tolerant taxa in forest community composition, which may suggest widespread shifts in similar directions (Enquist and Enquist 2011; Feeley et al. 2011). Although overall most genera did not show significant changes, the pronounced increase in BA loss and stem mor- tality for wet-affiliates would suggest a potential slowing of growth rates for this group, which could be an indication of climate sensitivity or long-term successional processes. These changes, combined with an increase in all four mea- sures of dynamism for climate-generalists in the north-west broadly reflects earlier findings (Lewis et al. 2004b; Phillips et al. 2004), that forests in the west of the region have been changing more rapidly than those in the east. Wet-affiliate BA gain decreased in the south-west, while stand-level analyses showed no significant change in stem numbers. If this group is decreasing in gain and increasing in loss (in the north-west), a shift in community composition could be suggested. It is difficult to isolate this as a marked trend, although it is supported by the strong relative increase in dry-affiliate numbers in the region. Our climate analyses showed no significant changes in precipitation seasonality in the north-west and south- west, which suggests that any changes in forest compo- sition with regard to our climate functional groups are unlikely to be driven by changes in rainfall regime alone in this region. However, while interannual precipitation trends were insignificant in the three regions (Malhi and Wright 2004), the increasing dry season length com- bined with the changes in dry season cloud fraction and cloud-related diffuse radiation, temperature and incoming D ow nl oa de d by [Q ue en sla nd U niv ers ity of T ec hn olo gy ] a t 2 1:4 0 1 0 A pri l 2 01 4 272 N. Butt et al. Figure 2. Direction and magnitude of changes in (a) basal area loss and gain and (b) stem mortality and recruitment between Interval 1 and Interval 2 for all plots, mean plot %, by climate functional group. Standard error bars (95% confidence limits). The rates of change for each of the three functional groups and across each region separately are shown in gain vs. loss plots to illustrate both absolute magnitude and changes in parameters. For basal area, ‘gain’ here includes recruitment and growth, while stem gain is recruitment only; ‘loss’ for basal area and stems is mortality. Net change is the difference between gain and loss. In these figures, points close to the 1:1 line are in dynamic equilibrium (gain ≈ loss); P values give the significance of difference from the 1:1 line. Points below the line indicate greater gain than loss, and points above the line greater loss than gain. Distance from the origin is an indicator of overall dynamism and turnover (but not equal to turnover sensu strictu). The error bars represent standard error. short-wave solar radiation (Malhi and Wright 2004; Butt et al. 2009; Hashimoto et al. 2010; Arias et al. 2011; Marengo et al. 2011), may increase transpiration and hence seasonal water stress even with no change in precipita- tion seasonality. They may thus be responsible for the increase in dry-affiliate stem recruitment in the south-west, while wet-affiliates and climate-generalist groups may be becoming more vulnerable to moisture stress induced by higher dry season transpiration rates (Malhi et al. 2009). In addition, temperature increase may drive increases in nutrient availability through more rapid decay and miner- alisation of litter, and the more dynamic species or groups (including drier groups) are able to respond rapidly (Lewis et al. 2004a; 2009). A drought classification and subsequent analysis of forest dynamics derived from trees in plots across the same (as above) Panama moisture gradient, using a similar method to our work, concluded that species distribution and forest composition was driven by seasonal and spa- tial variation in moisture availability, especially in drier D ow nl oa de d by [Q ue en sla nd U niv ers ity of T ec hn olo gy ] a t 2 1:4 0 1 0 A pri l 2 01 4 Compositional shifts in lowland Amazon forests 273 Figure 3. Gain/loss diagram for (a) basal area gains and losses, and (b) stem recruitment and mortality, for all climate-functional groups, for the north-west region. The total for all climate-functional group stems, ‘all’ (the three functional groups combined) is included (grey line). Wet-affiliates and climate-generalists all showed a significant (P < 0.05, z1.645 and P < 0.01, z2.326) increase in basal area loss, which brought them into dynamic equilibrium in the second interval (gain ∼ loss). Climate-generalists also showed a significant increase in basal area gain (P < 0.05, z1.645). Wet-affiliates moved from a state of net stem gain (P < 0.07, z1.484) into dynamic equilibrium (P < 0.9, z−1.315), while a significant increase (P < 0.01, z2.326) in climate-generalist dynamism moved this group into disequilibrium (net stem loss). Wet-affiliate and climate-generalist groups showed a significant increase in stem mortality (P < 0.05, z1.645 and P < 0.01, z2.326, respectively), causing an overall increase in stem mortality (P < 0.05, z1.645). The dry-affiliate group, a very small component of trees in these plots, has extremely low dynamism and was in equilibrium. years, when moisture stress increased (Engelbrecht et al. 2007; Comita and Engelbrecht 2009). This suggests that changes in moisture seasonality would drive shifts in for- est composition; an increase in seasonality would therefore support our first hypothesis, that drought-tolerant groups would be favoured by these changes. Drought-intolerant genera, while increasing in mortality, showed no decrease in growth, suggesting that the rising CO2 concentrations (from 346 ppmv in 1985 to 380 ppmv in 2005 – Carbon Dioxide Research Group, Mauna Loa) have counteracted any negative impacts of moisture stress for this group. There are indications of some changes in stand-level stem numbers and BA for the different climate-functional groups. Wet-affiliates, or drought-intolerant plants, also tend to be shade tolerant (Butt et al. 2008), and the fact that they showed significant increases in both BA loss and stem loss, but no significant gains in either BA or stem recruitment, in the wetter north-west could suggest that forests are beginning to shift towards more generalist communities. If the climate functional groups are also associated with shade tolerance and temperature sensi- tivity, these factors could be driving such a shift. The D ow nl oa de d by [Q ue en sla nd U niv ers ity of T ec hn olo gy ] a t 2 1:4 0 1 0 A pri l 2 01 4 274 N. Butt et al. Figure 4. Gain/loss diagram for stem gains and losses, for all climate-functional groups, for the south-west region. The regional total for each climate-functional group stems, ‘all’ (all three functional groups combined, for each region) is included (grey line). Climate- generalists and wet-affiliates started in stem equilibrium and remained there in the second interval. Dry-affiliates showed a significant increase in stem recruitment (P < 0.01) and moved from net stem loss to net stem gain. parallel increase in dry-affiliates could also support such a shift. The clear link between climate sensitivity, as defined here by moisture seasonality affiliation and dynamism, is ecologically interesting; currently, dry-affiliate plants are the least dynamic of the climate-functional groups, but if forest conditions become drier there may be further increases in dry-affiliates and dry-affiliate dynamism. Such shifts away from wetter communities and towards more generalist and drier communities could have positive con- sequences for forest persistence under future climate drying conditions, and further implications for forest productivity and carbon sequestration (Toledo et al. 2011b). In addition to possible climate drivers of changes in composition and dynamics, forests may be recover- ing from previous disturbances and at different stages of recovery/succession, thus exhibiting shifts in dynamism (Wright 2005; Lewis et al. 2009; Feeley et al. 2011); how- ever, the approach we used in this paper, of many plots spread over a large geographic region, should reduce the relative importance of disturbance events at stand level. Other related factors which may influence the estimation of changes in composition include lag-times: (i) between seedling recruitment and growing to 10 cm dbh, which may be very long and stochastic; (ii) for dying, and (iii) for recovery after drought events. Although our analysis con- siders changes prior to the extreme droughts of 2005 and 2010 (Lewis et al. 2011), it is possible that earlier droughts influenced growth rates, maybe even sufficiently to cause a directional change in composition. We note that the dry-affiliate functional group as defined here accounts for only a very small fraction (<2%) of stem numbers or BA in the plots, and hence does not indicate a large impact on overall community dynamics or a strong shift in overall community composition, but rather a shift related to water status. It is possible, however, that the group represents part of a wider spectrum of dry-favouring genera that remain unclassified into functional group, or allocated as climate-generalists, in which case there may already have been substantial overall shifts in community composition in either direction along the wet–dry affiliation spectrum. Finally, it should be noted that the period analysed in this paper (overall, 20 years split in two) is still rela- tively short for identifying long-term trends. Nevertheless, parts of Amazonia experienced two strong droughts after the period of this study, in 2005 (Aragao et al. 2007) and 2010 (Lewis et al. 2011), which may sharpen the tendency towards increasing abundance of dry-affiliates. The present analysis provides initial clues to functional compositional changes occurring in Amazonian forests; these will need to be tested with longer-term, and more trait-based, analyses of functional groups. Acknowledgements N. Butt’s Ph.D. was funded by the UK Natural Environment Research Council. We thank those who contributed field data: L. Arroyo, F. Cornejo, N. Higuchi, E. Honorio, I. Huamantupa, N. Jaramillo, R. Luizão, A. Monteagudo, D. Neill, A. Pena Cruz, J. Pipoly, J. Terborgh, M. Silva, P. Nuñez, and R. Vasquez. Thanks also to Toby Marthews for his help with R coding. Funding for plot monitoring in Amazonia was provided by grants to OP and YM from NERC, the EU Framework V, and the National Geographic Society. OP is supported by an Advanced Grant from the European Research Council. Simon L. Lewis is supported by the Royal Society. The manuscript was improved by comments from Lourens Poorter, Sharon Strauss and two anonymous refer- ees. This paper is dedicated to the memory of co-author Samuel Almeida, a committed Amazon forest ecologist who passed away during the preparation of the manuscript. D ow nl oa de d by [Q ue en sla nd U niv ers ity of T ec hn olo gy ] a t 2 1:4 0 1 0 A pri l 2 01 4 Compositional shifts in lowland Amazon forests 275 Figure 5. Comparison of changes between census intervals for the dry-affiliate group, including and excluding Aspidosperma, for (a) basal area gain and loss, and (b) stem recruitment and mortality. (East-central is not included as the dry-affiliate group comprised only Aspidosperma in this region; there were no dry-affiliate-excluding Aspidosperma stem changes in the north-west). Table 3. Comparison of changes for the dry-affiliate group by including vs. excluding Aspidosperma. % annual change between intervals All dry-affiliates Excluding Aspidosperma North-west BA gain 0.82 1.86 BA loss 0.01 0 Stem recruitment −0.13 0 Stem mortality −0.20 0 South-west BA gain 0.21 0.61 BA loss 0.11 0.08 Stem recruitment −0.95 −1.86 Stem mortality −0.19 0 Notes on contributors Nathalie Butt is a climate and ecosystem scientist with research interests in tropical and temperate forest ecology. Yadvinder Malhi is Professor of Ecosystem Science. He focuses on interactions between forest ecosystems and the global atmo- sphere, and carbon, energy and water cycles. Mark New works on observed climate change and climate change impacts. Manuel J. Macía is an assistant professor. He works on the biodiversity and conservation of vascular plants in north-west South America and the integration of ecological and ethnobotani- cal studies. Simon L. Lewis is a plant ecologist and global change science researcher. D ow nl oa de d by [Q ue en sla nd U niv ers ity of T ec hn olo gy ] a t 2 1:4 0 1 0 A pri l 2 01 4 276 N. Butt et al. Gabriela Lopez-Gonzalez researches ecoinformatics and plant functional characteristics and works on a database of forest inven- tories (www.forestplots.net) and functional traits information. William Laurance is a research professor studying the impacts of land use and climate change on tropical forest ecosystems and biodiversity. Susan Laurance is a senior lecturer and her research focuses on tropical forest dynamics and landscape ecology. Regina Luizão is an ecologist with research interests in biodiversity and nutrient cycling in tropical forests. Ana Andrade is the herbarium manager for the Biological Dynamics of Forest Fragments Project in Manaus, Brazil (BDFFP). Timothy Baker is a tropical forest ecologist and works on the carbon dynamics, evolution and conservation of tropical forest ecosystems. Oliver Phillips is Professor of Tropical Ecology. His work focuses on the dynamics of carbon and biodiversity across the world’s tropical forests and how these change with changing climate. References Aragao LEOC, Malhi Y, Roman-Cuesta RM, Saatchi S, Anderson LO, Shimabukuro YE. 2007. Spatial patterns and fire response of recent Amazonian droughts. Geophysical Research Letters 34:L07701. Arias PA, Fu R, Hoyos CD, Li WH, Zhou LM. 2011. Changes in cloudiness over the Amazon rainforests during the last two decades: diagnostic and potential causes. Climate Dynamics 37:1151–1164. Baker T, Phillips OL, Malhi Y, Almeida A, Arroyo L, Di Fiore A, Erwin T, Killeen TJ, Laurance SG, Laurance WF, et al. 2004. Variation in wood density determines spatial pat- terns in Amazonian forest biomass. Global Change Biology 10:545–562. Beer C, Reichstein M, Tomelleri E, Ciais P, JungM, Carvalhais N, Rödenbeck C, Altaf Arain M, Baldocchi D, Bonan GD, et al. 2010. Terrestrial gross carbon dioxide uptake: global distribu- tion and covariation with climate. Science 329:834–838. Butt N, Malhi Y, Phillips O, New M. 2008. Floristic and func- tional affiliations of woody plants with climate in western Amazonia. Journal of Biogeography 35:939–950. Butt N, New M, Lizcano G, Malhi Y. 2009. Spatial patterns and recent trends in cloud fraction and cloud-related diffuse radiation in Amazonia. Journal of Geophysical Research – Atmospheres 114:D21104. Chave J, Condit R, Muller-Landau H-C, Thomas SC, Ashton PS. 2008. Assessing Evidence for a Pervasive Alteration in Tropical Tree Communities. Public Library of Science – Biology 6:e45. Comita LS, Engelbrecht BMJ. 2009. Seasonal and spatial varia- tion in water availability drive habitat associations in a tropical forest. Ecology 90:2755–2765. Condit R. 1998. Ecological implications of changes in drought patterns: shifts in forest composition in panama. Climatic Change 39:413–427. Cramer W, Bondeau A, Woodward FI, Prentice IC, Betts RA, Brovkin V, Cox PM, Fisher V, Foley JA, Friend AD, et al. 2001. Global response of terrestrial ecosystem structure and function to CO2 and climate change: results from six dynamic global vegetation models. Global Change Biology 7: 357–373. Curtis PS, Wang XZ. 1998 A meta-analysis of elevated CO2 effects on woody plant mass, form and ecology. Oecologia 113:299–313. Engelbrecht BMJ, Comita LS, Condit R, Kursar TA, Tyree MT, Turner BL, Hubbell SJ. 2007. Drought sensitivity shapes species distribution patterns in tropical forests. Nature 447:80–82. Enquist BJ, Enquist CAF. 2011. Long-term changes within a Neotropical forest: assessing differential functional and floristic responses to disturbance and drought. Global Change Biology 17:1408–1424. Farquhar GD. 1997. Carbon dioxide and vegetation. Science 278:1411. Feeley KJ, Davies SJ, Perez R, Hubbell SP, Foster RB. 2011. Directional change in the species composition of a tropical forest. Ecology 92:871–882. Gentry A. 1988. Changes in plant community diversity and floristic composition on environmental and geographical gradients. Annals of the Missouri Botanical Garden 75: 1–34. Hashimoto H, Melton F, Ichii K, Miles C, Wang W, Nemani RR. 2010. Evaluating the impacts of climate and elevated carbon dioxide on tropical rainforests of the western Amazon basin using ecosystem models and satellite data. Global Change Biology 16:255–271. IPCC. 2007. Climate Change 2007: The Physical Science Basis. In: Solomon S, Qin D, Manning M, Chen Z, Marquis M, Averyt KB, Tignor M, Miller HL, editors. Climate change 2007: The physical science basis. Contribution of Working Group I to the fourth assessment report of the intergovern- mental panel on climate change. Cambridge (UK): Cambridge University Press. Laurance WF, Oliveira AA, Laurance SG, Condit R, Nascimento HEM, Sanchez-Thorin AC, Lovejoy TE, Andrade A, D’Angelo S, Ribeiro JE, et al. 2004. Pervasive alteration of tree communities in undisturbed Amazonian forests. Nature 428:171–175. Lewis SL, Brando PM, Phillips OL, van der Heijden GMF, Nepstad D. 2011. The 2010 Amazon drought. Science 331:554. Lewis SL, Lloyd J, Sitch S, Mitchard ETA, Laurance WF. 2009. Changing ecology of tropical forest: evidence and drivers. Annual Reviews in Ecology, Evolution and Systematics 40:529–549. Lewis SL, Malhi Y, Phillips OL. 2004a. Fingerprinting the impacts of global change on tropical forests. Philosophical Transactions of the Royal Society of London Series B-Biological Sciences 359:437–462. Lewis SL, Phillips OL, Baker TR, Lloyd J, Malhi Y, Almeida S, Higuchi N, Laurance WF, Neill DA, Silva JNM, et al. 2004b. Concerted changes in tropical forest struc- ture and dynamics: evidence from 50 South American long-term plots. Philosophical Transactions of the Royal Society of London Series B-Biological Sciences 359: 421–436. Lopez-Gonzalez G, Lewis SL, Phillips OL, Burkitt M. Forest Plots Database. www.forestplots.net. Extracted: 2009 + 2011. Lopez-Gonzalez G, Lewis SL, Burkitt M, Phillips OL. 2011. ForestPlots.net: a web application and research tool to man- age and analyse tropical forest plot data. Journal of Vegetation Science, 22:610–613. Malhi Y, Aragão LEOC, Galbraith D, Huntingford C, Fisher R, Zelazowski P, Sitch S, McSweeney C, Meir P. 2009. Exploring the likelihood and mechanism of a climate-change- induced dieback of the Amazon rainforest. Proceedings of the National Academy of Sciences of the United States of America 106:20610–20615. Malhi Y, Phillips OL, Lloyd J, Baker T, Wright J, Almeida S, Arroyo L, Frederiksen T, Grace J, Higuchi N, et al. 2002. An international network to monitor the structure, composition and dynamics of Amazonian forests (RAINFOR). Journal of Vegetation Science 13:439–450. D ow nl oa de d by [Q ue en sla nd U niv ers ity of T ec hn olo gy ] a t 2 1:4 0 1 0 A pri l 2 01 4 Compositional shifts in lowland Amazon forests 277 Malhi Y, Wood D, Baker TR, Wright J, Phillips OL, Cochrane T, Meir P, Chave J, Almeida S, Arroyo L, et al. 2006. The regional variation of aboveground live biomass in old- growth Amazonian forests. Global Change Biology 12: 1107–1138. Malhi Y, Wright J. 2004. Spatial patterns and recent trends in the climate of tropical forest regions. Philosophical Transactions of the Royal Society of London Series B-Biological Sciences 359:311–329. Marengo JA, Tomasella J, Alves LM, Soares WR, Rodriguez DA. 2011. The droughts of 2010 in the context of historical droughts in the Amazon region. Geophysical Research Letters 38:L12703. Nemani RR, Keeling CD, Hashimoto H, Jolly WM, Piper SC, Tucker CJ, Myneni RB, Running SW. 2003. Climate-driven increase in global terrestrial net primary production from 1982 to 1999. Science 300:1560–1563. New M, Hulme M, Jones P. 1999. Representing twentieth cen- tury space-time climate variability. I. Development of a 1961–90 mean monthly terrestrial climatology. Journal of Climate 12:829–856. Norby RJ, Wullschleger SD, Gunderson CA, Johnson DW, Ceulemans R. 1999. Tree responses to rising CO2: impli- cations for the future forest. Plant, Cell & Environment 22:683–714. Parmesan C, Yohe G. 2003. A globally coherent fingerprint of climate change impacts across natural systems. Nature 421:37–42. Phillips OL, Aragão LEOC, Lewis SL, Fisher JB, Lloyd J, López- González G, Malhi Y, Monteagudo A, Peacock J, Quesada CA, et al. 2009. Drought sensitivity of the Amazon rainforest. Science 323:1344–1347. Phillips OL, Baker TR, Arroyo L, Higuchi N, Killeen TJ, Laurance WF, Lewis SL, Lloyd J, Malhi YM, Monteagudo A, et al. 2004. Pattern and process in Amazon tree turnover, 1976–2001. Philosophical Transactions of the Royal Society of London Series B-Biological Sciences 359:381–407. Phillips OL, Malhi Y, Higuchi N, Laurance WF, Nunez PV, Vasquez RM, Laurance SG, Ferreira LV, Stern M, Brown S, et al. 1998. Changes in the carbon balance of tropical forests: Evidence from long- term plots. Science 282:439–442. Phillips OL, Vasquez RM, Arroyo L, Baker T, Killeen TJ, Lewis SL, Malhi Y, Monteagudo AL, Neill D, Nunez PV, et al. 2002. Increasing dominance of large lianas in Amazonian forests. Nature 418:770–774. Schnitzer SA, Bongers F. 2011. Increasing liana abundance and biomass in tropical forests: emerging patterns and putative mechanisms. Ecology Letters 14:397–406. ter Steege H, Pitman N, Sabatier D, Castellanos H, Van Der Hout P, Daly DC, Silveira M, Phillips OL, Vasquez R, Van Andel T, et al. 2003. A spatial model of tree alpha-diversity and tree density for the Amazon. Biodiversity and Conservation 12:2255–2277. Toledo M, Poorter L, Peña-Claros M, Alarcón A, Balcázar J, Leaño C, Licona JC, Bongers F. 2011a. Climate and soil drive forest structure in Bolivian lowland forests. Journal of Tropical Ecology 27:1–13. Toledo M, Poorter L, Peña-Claros M, Alarcón A, Balcázar J, Leaño C, Licona JC, Llanque O, Vroomans V, Zuidema P, et al. 2011b. Climate is a stronger driver of tree and forest growth rates than soil and disturbance. Journal of Ecology, 99:254–264. Winter K, Aranda J, Garcia M, Virgo A, Paton SR. 2001. Effect of elevated CO2 and soil fertilization on whole-plant growth and water use in seedlings of a tropical pioneer tree, Ficus insipida Willd. Flora 196:458–464. Woodward FI, Lomas MR. 2004. Vegetation dynamics – simulating responses to climatic change. Biological Reviews 79:1–28. Wright SJ. 2005. Tropical forests in a changing environment. Trends in Ecology and Evolution 20:553–560. Wright SJ, Calderón O, Hernandéz H, Paton S. 2004. Are lianas increasing in importance in tropical forests? A 17-year record from Panama. Ecology 85:484–489. D ow nl oa de d by [Q ue en sla nd U niv ers ity of T ec hn olo gy ] a t 2 1:4 0 1 0 A pri l 2 01 4 278 N. Butt et al. Appendix 1. Plot and census information Plots sited very closely together and 0.25 ha or less were combined; 12 plots became three in the east-central region. Plot Plot name Latitude Longitude Plot area (ha) Census 1 Census 2 Census 3 ALM-01 Altos de Maizal −11.8 −71.47 2 1994 1999 2004 ALP-11 Allpahuayo A poorly drained −3.95 −73.43 0.44 1990 1996 2005 ALP-12 Allpahuayo A, very well drained −3.95 −73.44 0.4 1990 1996 2005 ALP-21 Allpahuayo B, sandy −3.95 −73.44 0.48 1990 1996 2005 ALP-22 Allpahuayo B, clayed −3.95 −73.44 0.44 1990 1996 2005 BDF-03 BDFFP, 1101 Gaviao −2.4 −59.9 1 1987 1991 2003 BDF-04 BDFFP, 1102 Gaviao −2.4 −59.9 1 1987 1991 2003 BDF-05 BDFFP, 1103 Gaviao −2.4 −59.9 1 1987 1991 2003 BDF-06 BDFFP, 1201 Gaviao −2.4 −59.9 3 1986 1992 2003 BDF-07 BDFFP, 1105 Gaviao −2.4 −59.9 1 1988 1999 2004 BDF-08 BDFFP, 1109 Gaviao −2.4 −59.9 1 1988 1999 2004 BDF-09 BDFFP, 1113 Florestal −2.4 −59.9 1 1987 1992 2002 BDF-10 BDFFP, 1301 Florestal 1 = plot 1301.1 and 1301.3 −2.4 −59.9 2 1988 1997 2002 BDF-11 BDFFP, 1301 Florestal 2 = plots 1301.4,5,6 −2.4 −59.9 3 1988 1997 2002 BDF-12 BDFFP, 1301 Florestal 3 = plots 1301.7,8 −2.4 −59.9 2 1988 1997 2002 BDF-13 BDFFP, 3402 Cabo Frio −2.4 −59.9 9 1985 1991 2003 BDF-14 BDFFP, 3304 Porto Alegre −2.4 −59.9 1 1987 1992 2003 BNT-01 Bionte 1 −2.63 −60.17 1 1986 1995 2005 BNT-02 Bionte 02 −2.63 −60.17 1 1986 1995 2004 BNT-04 Bionte 4 −2.63 −60.15 1 1986 1995 2005 CAX-01 Caxiuana 1 −1.74 −51.46 1 1994 1999 2004 CUZ-01 Cuzco Amazonico, CUZAM1E −12.58 −69.15 1 1989 1994 2003 CUZ-02 Cuzco Amazonico, CUZAM1U −12.58 −69.15 1 1989 1994 2003 CUZ-03 Cuzco Amazonico, CUZAM2E −12.50 −68.96 1 1989 1994 2003 CUZ-04 Cuzco Amazonico, CUZAM2U −12.56 −69.13 1 1989 1994 2003 JAS-02 Jatun Sacha 2 −1.07 −77.6 1 1987 1994 2002 JAS-03 Jatun Sacha 3 −1.07 −77.67 1 1988 1994 2002 JAS-05 Jatun Sacha 5 −1.07 −77.67 1 1989 1994 2002 JRI-01 Jari 1 −0.89 −52.19 1 1985 1990 1996 MNU-01 Manu, alluvial Cocha Cashu Trail 3, M1 −11.87 −71.35 1 1990 1995 2000 MNU-03 Manu, terra firme terrace, M3 −11.88 −71.35 2 1991 1996 2001 MNU-04 Manu, terra firme ravine, M4 −11.88 −71.35 2 1991 1996 2001 MNU-05 Manu, alluvial Cocha Cashu Trail 12 −11.87 −71.35 2 1989 1994 1999 MNU-06 Manu, alluvial Cocha Cashu Trail 2 & 31 −11.87 −71.35 2.25 1989 1994 2004 RES-03 Porongaba 1 −10.82 −68.77 1 1991 1999 2003 RES-04 Porongaba 2 −10.80 −68.77 1 1991 1999 2003 SUC-01 Sucusari A −3.25 −72.91 1 1992 1996 2005 SUC-02 Sucusari B −3.25 −72.90 1 1992 1996 2005 SUM-01 Sumaco −1.75 −77.63 1 1989 1996 2002 TAM-01 Tambopata plot zero −12.84 −69.29 1 1987 1994 2003 TAM-02 Tambopata plot one −12.83 −69.29 1 1987 1994 2003 TAM-04 Tambopata plot two swamp edge clay −12.84 −69.28 0.42 1985 1990 2003 TAM-05 Tambopata plot three −12.83 −69.27 1 1986 1994 2005 TAM-06 Tambopata plot four −12.84 −69.30 1 1991 1998 2005 TAM-07 Tambopata plot six −12.83 −69.26 1 1985 1994 2003 YAN-01 Yanamono A −3.44 −72.85 1 1989 1996 2005 D ow nl oa de d by [Q ue en sla nd U niv ers ity of T ec hn olo gy ] a t 2 1:4 0 1 0 A pri l 2 01 4 Compositional shifts in lowland Amazon forests 279 Appendix 2 The Gentry dataset of 0.1 ha floristic samples was used (http:// www.salvias.net/pages/index.html) for all woody stems ≥2.5 cm dbh. Vouchers of plants were collected and identified at the Missouri Botanic Garden. The analysis used 39 plots below 1000 m elevation (lowland) and west of 62◦ W, including additional data for four 0.1 ha plots in Yasuní, Ecuador, provided by MJ Macia. A measure of relative abundance (percentage frequency of each tree genus per plot) was calculated to enable comparisons in the representation of each genus across plots and varying precipitation regimes, and to account for the differences in plant numbers between plots. Species diversity was such that most species were too rare (e.g. fewer than one individual per sample unit) to include in the analysis. As many more trees were accurately identified to genus than to species (about 30% of all trees recorded were not identified to species level, and many identified only to morphospecies), genus-level plant distribution data were used. Climate data were obtained from the Climate Research Unit (CRU) 0.5-degree global dataset (New et al. 1999). From this monthly dataset, precipitation data were used to derive a measure of dry season intensity for rainfall and rainfall-related variables. For each half-degree pixel, the sum of the precipitation in the driest three months was calculated and then used as a dry season (intensity) measure. Two other precipitation-related vari- ables were also included: soil water content (SWC) and potential evapotranspiration minus precipitation (PET - p). The SWC estimates were obtained from the Sheffield dynamic vegetation Table A1. Rainfall seasonality ranking for woody genera in the western Amazon. The rankings, derived from Kendall’s t coefficients, range approximately between 0.5 (strongly wet-affiliated) and −0.4 (strongly dry-affiliated). Generally values between around 0.2 and −0.2 indicate no significant correlation with rainfall. (The asterisked genera are those with a statistically significant correlation; P < 0.05 or P < 0.01 equivalents after the application of Bonferroni’s correction for multiple comparisons). Source: Butt et al. (2008). ∗Acacia −0.395 Cissus 0.105 ∗Miconia 0.228 ∗Arrabidaea −0.380 Tapirira 0.107 Eugenia 0.229 ∗Capparis −0.359 Socratea 0.118 ∗Paullinia 0.241 ∗Aspidosperma −0.357 Tachigali 0.125 Pithecellobium 0.243 Serjania −0.277 Caraipa 0.128 ∗Coussarea 0.267 Hippocratea −0.273 Geonoma 0.138 ∗Strychnos 0.282 Cydista −0.223 Sorocea 0.138 ∗Talisia 0.289 Hirtella −0.149 Unonopsis 0.142 ∗Theobroma 0.290 Combretum −0.121 Clusia 0.145 ∗Iryanthera 0.295 Forsteronia −0.120 Pourouma 0.146 ∗Licania 0.306 Clytostoma −0.097 Brosimum 0.150 ∗Aniba 0.312 Sclerolobium −0.083 Dalbergia 0.164 ∗Eschweilera 0.314 Zanthoxylum −0.083 Cecropia 0.171 ∗Swartzia 0.330 Adenocalymna −0.080 Doliocarpus 0.171 ∗Virola 0.341 Oenocarpus −0.075 Rinorea 0.175 ∗Duguetia 0.344 Cordia −0.057 Tetragastris 0.183 ∗Perebea 0.347 Piper −0.035 Leonia 0.183 ∗Mabea 0.349 Lonchocarpus −0.033 Casearia 0.185 ∗Protium 0.352 Euterpe −0.025 Salacia 0.187 ∗Endlicheria 0.353 Xylopia −0.019 Naucleopsis 0.200 ∗Guatteria 0.358 Celtis −0.018 Trigynaea 0.201 ∗Bauhinia 0.361 Neea 0.028 Sloanea 0.201 ∗Otoba 0.371 Allophylus 0.039 Ficus 0.203 ∗Cyathea 0.378 Siparuna 0.043 Apeiba 0.205 ∗Faramea 0.381 Scheelea 0.053 Astrocaryum 0.208 ∗Inga 0.391 Quararibea 0.053 Carpotroche 0.208 ∗Guarea 0.424 Coccoloba 0.071 Trichilia 0.215 ∗Psychotria 0.454 Mouriri 0.078 Callichlamys 0.216 ∗Sterculia 0.473 Pseudolmedia 0.086 Pouteria 0.219 ∗Machaerium 0.482 Erythroxylum 0.096 Bactris 0.222 Ocotea 0.104 Iriartea 0.227 global model (Woodward and Lomas 2004), and PET (from CRU) was calculated from temperature, sunshine/radiation, wind and humidity data using the Penman–Monteith equation. The dataset created for the analysis represented the average monthly climate (1961–98). Relative abundance was determined for each woody plant genus for each plot and only genera that occurred in one or more plots (91 genera), with over 1% abundance analysed (rep- resenting 59% of 20,000 recorded stems in these plots). For each genus, each moisture variable (dry quarter precipitation, PET - p, SWC) was correlated with the relative abundance of that genus across all sites and correlation coefficients (Kendall’s t) averaged to produce a rainfall seasonality ranking. The 91 genera were then each initially classified as one of two categories: no correlation with moisture, or correlation with one, two or three moisture vari- ables, and, of those correlated with the moisture variables, each genus was then associated with wetter or drier conditions, accord- ing to the correlation coefficients (Table A1). The results gave significant correlations for a third of these genera with either wet- ter (designated as ‘wet-affiliates’) or drier conditions (designated as ‘dry-affiliates’): two-thirds, with no moisture seasonality affil- iation, were designated as ‘climate-generalists’. 12% of genera and 60% of individuals were thus classified – the remainder was unclassified because of low abundances (see Butt et al. 2008). In the current analysis, the climate functional groups represent about 60% of individuals and >20% of genera in the plots used (the rest were unclassified, ‘unknown’ and were not included in all subsequent analyses). D ow nl oa de d by [Q ue en sla nd U niv ers ity of T ec hn olo gy ] a t 2 1:4 0 1 0 A pri l 2 01 4 D ow nl oa de d by [Q ue en sla nd U niv ers ity of T ec hn olo gy ] a t 2 1:4 0 1 0 A pri l 2 01 4