DOI: 10.5061/dryad.r7sqv9shz
title: Data from: Mast fruiting in a large tropical African legume tree provides evidence for the nutrient resource limitation hypothesis

description: The large grove-forming tropical tree Microberlinia bisulcata
 (Fabaceae subfamily Detarioideae) at Korup, Cameroon, shows strong mast
 fruiting. Reproductive allocation is considerable. The site has very
 nutrient-poor soil. To test the nutrient resource limitation hypothesis,
 phenological recordings between 1989 and 2017 were matched with climate
 variables and analyzed using logistic time-series regression. Masting
 happened mostly on 2- or 3-year cycles. A strong predictor was mean daily
 rainfall in the dry season: low in the current year of masting and high in
 the year prior. Less strongly predictive was the increase in dry season
 radiation between prior and mast years. Masting events showed no
 relationship to annual stem increment, nor with local plantation yields.
 Later, the normally heavy mastings became moderate after two attacks by
 caterpillars. Collated studies of fallen leaf nutrient concentrations
 showed that P increased markedly, K rose and fell, but N and Mg changed
 little, in the inter-mast interval. P and K were likely being accumulated
 and stored and then triggered masting events when internal thresholds were
 crossed. The drier season prior to masting enabled a rise in C, and the
 wetter season the year before, with higher soil moisture, enabled better
 acquisition and uptake of nutrients by roots and mycorrhizas. The main
 storage of P may be in bark and branches, that for K on soil
 organic-colloids. A rooting-fruiting trade-off in C allocated over a
 minimal 2-year cycle is implied. The hypothesis is that synchrony among
 masting trees may be achieved, in part, by equilibration of P across the
 mycorrhizal network. The long-term driver appears to be the inherent
 year-to-year stochasticity of dry-season rainfall, the realization of
 which leads to an important refinement of the hypothesis. Life history
 strategy linked to nutrient resource dynamics provides a plausible
 explanation and more advanced hypothesis for the masting events observed.
description: The files in this archive are from different
 parts or aspects of a long-term study over 29 years of the fruiting
 phenology of the tree species <em>Microberlinia bisulcata</em>
 at Korup National Park, SW Cameroon. The time series of recorded mast
 fruiting events between 1989 and 2004 (reported and analyzed in Newbery et
 al. 2006) has been extended here to 2017. A second period of detailed leaf
 fall and flushing, flower, and fruit phenology between 2009 and 2014 is
 included, complementing the earlier similar one between 1995 and 2000
 (Newbery et al. 2006). The basic methodology was one of scoring samples of
 trees for phenology over time within specific periods in the large
 permanent P-plot at Korup (Newbery et al. 2013), and outside of these
 periods, annual assessments were made. Masting occurrence over the full
 period is matched with climate data variables (mean daily dry-season
 rainfall and radiation; start and duration of the dry season). The raw
 daily climate data for 1984 to 2017 are found in Etta et al. 2022: see
 'Related Works' below), Data are also presented for soil
 moisture contents from 2003 to 2005, leaf and fruit nutrient
 concentrations from two studies at the site in 1998 and 2011, and annual
 stem growth increment data derived from tree cores from 1989 to 2003 (see
 Newbery et al. 2013). For comparison with forest fruiting, data on oil
 palm yield in estates outside the Park are presented for 2003 to 2016. The
 methods are detailed in the main paper. 
 Newbery, D. M., G. B. Chuyong, and L. Zimmermann. 2006.
 "Mast fruiting of large ectomycorrhizal African rain forest trees:
 importance of dry season intensity, and the resource-limitation
 hypothesis."  New Phytologist 170 (3):561-579. doi:
 10.1111/j.1469-8137.2006.01691.x. Newbery, D. M., X.
 M. van der Burgt, M. Worbes, and G. B. Chuyong. 2013. "Transient
 dominance in a central African rain forest."  Ecological Monographs
 83 (3):339-382. doi: 10.1890/12-1699.1.
description: The files are all in .csv (comma-separated
 values) format, and can be readily read by most statistical programs and
 software. The masting and climate variables form the basis for the
 binomial, ordinal, and time-series regression modelling. The data will
 allow rerunning of model fitting and other analyses, using standard
 statistical methods as described in the main paper, and also the
 reconstruction of the figures and tables of both the paper and its
 appendices.
description: # Data from: Mast fruiting in a large tropical African legume tree
 provides evidence for the nutrient resource limitation hypothesis ## Dry
 season climate “dry-season_climate_1984-2017.csv” has the climate
 variables for drought-defined dry seasons from 1984 (start) to 2017
 (closure) at the PAMOL Bulu Station. The dry season for a given year (row
 of table) may have started some weeks, typically in December, of the year
 prior. Estimates are mean daily values across the season, units given in
 the column headers except for ‘radi’: ‘n-days’, length of the season;
 ‘maxT’ and ‘minT’, maximum and minimum temperatures (dry bulb); ‘rain’,
 rainfall; ‘rft’, running 30-day rainfall total; ‘radio’, volume water
 evaporated in Gunn-Bellani [GB] radiometer; ‘radi(GB1)’ and ‘radi(GB2)’,
 radiation (W m–2), as converted from ‘radio’ for the two radiometers,
 ‘radi(comb)’, combined estimates, including the interpolated values for
 missing years (in bold). See S1 Appendix of the main paper for radiation
 calibrations and interpolation method. ### &gt; Table 1, Fig. 2; {S4
 Appendix: Tables A & B, Figs A and B} ## Mast fruiting and climate
 “masting-climate_1989-2017.csv” has the masting and drought-defined dry
 season climate variables for 1989 to 2017: ‘mast’, intensity of mast
 fruiting on an ordinal scale (1, full mast [‘M’]; 0.5, moderate mast
 [‘m’]; 0, none); ‘start’ of dry season, being number of days since 1
 December (in year prior), ‘dur’, duration of season, i.e. its length in
 days; minimum temperature (deg. C); ‘rain’, mean daily rainfall (mm);
 ‘radi’, mean daily radiation (W m–2). Climate values are included for 1987
 and 1988 to allow derivation of 1- and 2-year lags. The binary-scale
 masting (1, 0) applies to 1989 to 2012. ### &gt; Fig. 1; {S3 Appendix:
 Figs B\[a] and C} ## Seasonal radiation “radi_seasonal_1987-2017.csv” has
 mean daily radiation (W m–2) for 1987 to 2017 in each of the four seasonal
 quarters of the year (months): ‘radi1’, DJF; ‘radi2’, MAM; ‘radi3’, JJA;
 ‘radi4’, SON; ‘radit’, whole year (total). ### &gt; {S3 Appendix: Figs A,
 B\[b] and D} ## Radiation differences “mast_radi-diffs_1989-2012.csv” has
 mean daily radiation (W m–2) in the current year of masting, as either
 drought-defined ‘radi’ or first seasonal-quarter defined [DJF] ‘radi1’ dry
 season, for 1989 to 2017. The ‘radi_1’ and ‘radi1_1’ are corresponding
 values at 1-year lag, with: ‘radi_diff’, the difference between successive
 years (current – prior); ‘radi_res(lin)’ and ‘radi1_res(lin)’, residuals
 from corresponding linear fits of ‘radi’ and ‘radi1’ to date; and
 ‘radi1_res(sth)’ and ‘radi1_1_res(sth)’, residuals from smoothed LOWESS
 fits of ‘radi1’ and ‘radi1_1’ to date. ### &gt; {S3 Appendix: Figs C and
 D}; {S4 Appendix: Table C, Figs C and D} ## Dry season rainfall
 “dryseas_rain&rtf_2003-2005.csv” and
 “dryseas_rain&rft_2010-2012.csv” have daily rainfall (mm), ‘rain03’ to
 ‘rain05’ and ‘rain10’ to ‘rain12’, recorded at Bulu, Ndian, over the
 annual periods 1 December to 31 March, which encompass the dry seasons of
 2003 to 2005 and 2010 to 2012, as ‘date03’ to ‘date05’ and ‘date10’ to
 ‘date12’. The corresponding running 30-day rainfall totals are in columns
 headed ‘rft03’ to ‘rft05’ and ‘rft10’ to ‘rft12’. (December values are
 from the calendar year prior.) ### &gt; {S5 Appendix: Figs A and B} ##
 Soil moisture “soil_moisture_2003-2005.csv” has means and standard errors
 (n = 9) of soil moisture contents (% dry mass) between 2 December 2003 and
 26 April 2005 (‘date’), and the matching 30-day running rainfall totals
 (‘rft’, mm). The 12 columns to the left have the individual sensor SMC
 values, headers for which combine sensor number, depth (cm) in
 parenthesis, and afterwards a ‘1’ (yes) or a ‘0’ (no) indicating whether
 the sensor values were used for finding the mean and se. ### &gt; Fig. 3
 ## Raw data on phenology “phenology_Mb_2010-2014.csv” has the raw field
 records on phenology over the years (end 2009) 2010 to 2014. Each column
 for these observations has a header which is a concatenation of ‘stadium’
 and ‘date’. Scoring was on the scale 0 to 3 (see main text of paper for
 explanation). Stadia: ‘fall’, leaf fall; ‘flush’, leaf flushing; ‘flower’,
 flowering; ‘gr-pods’, (immature) green pods, and ‘br-pods’, (mature) brown
 pods. Other columns: ‘tree’, tagged tree number in P-plot; ‘diam’, stem
 diameter at breast height from last census (in 2005); ‘EE’ and ‘NN’,
 distances eastwards respectively northwards from origin of plot (see
 Newbery et al. 2013: reference in main paper). ### &gt; Fig. 4 \[basis] ##
 Summarized phenology “phenol_Mb_2010.csv” and “phenol_Mb_2012.csv” have
 mean tree scores for recording dates between 19 December 2009 and 24
 August 2010, and between 30 November 2011 and 30 July 2012, respectively,
 for five phenological stadia (‘stadium10’, ‘stadium12’): same as for the
 ‘Raw data on phenology’ file (n = 61 trees). ### &gt; Figs 4a and 4b ##
 Leaf nutrients-1 “Mb_leaf-nutrients_1998.csv” has N and P concentrations
 (mg g–1) in litter trap samples of M. bisulcata leaves, over four
 fortnightly periods between 21.12.1997 and 15.02.1998 (‘dates’), in six
 HEM half-plots, of two subplots each, and nesting two types of trap:
 1,’HL’, hessian lining; 2, ‘GM’, galvanized metal. Leaves separate
 naturally on shedding into in two ‘parts’: 1, leaflets; and 2, rachises.
 The layout and design of the half-plots is described in Newbery et al.
 (1997): reference in the main paper. ### &gt; Table 2 ## Leaf nutrients-2
 “Mb_leaf-nutrients_2011.csv” has N, P, Ca, K and Mg concentrations (mg
 g–1) in hessian-bag litter trap samples of M. bisulcata leaves, of 29
 January 2011 (sample collection for previous month), in 30 subplots across
 the eastern 25 ha of the main P-plot, with two replicate locations per
 subplot, and leaves separated into two ‘parts’: 1, leaflets; and 2,
 rachises. The ‘mass’ of each bulked sample is listed also. For plot
 details see Newbery et al. (2013), and for trap layout, Norghauer and
 Newbery (2015): references in the main paper. ### &gt; Table 2 ## Fruit
 nutrients “seeds&pods_1998.csv” have the Ca, K and Mg concentrations
 (mg g–1) of M. bisulcata samples of seeds and pods (‘parts’) collected
 after the 1998 masting. For methodology see Green and Newbery (2002),
 where the complementary N and P values are also given. ### &gt; Table 3 ##
 Oil-palm yields “oil-palm-yields_2003-2016.csv” has the monthly total
 fresh-fruit bunch masses (metric tons) combined across the five
 plantations of the Ndian Estate, Mundemba, SW Cameroon, for the years 2003
 to 2016, as made available by PAMOL Plc. Dividing these values by ‘Area’
 gives production in t/ha/month. ### &gt; {S7 Appendix: Fig. A} ##
 Increment cores “stem_incr_1989-2003.csv” has the annual stem wood
 increments from cores of 20 M. bisulcata trees: ‘mast’ is a binomial
 variable (1 = ‘M’; 0 = none). Columns are for the individual trees, whose
 header labels are tree number prefixed by ‘P’, the last standing for the
 main P-plot (see Newbery et al. 2013: reference in main paper). The units
 are mm ? 102 (e.g. 250 units = 2.5 mm). ### &gt; {S8 Appendix: Fig. A}
 Note: Appendices S2 and S6 have no related data.