DOI: 10.5061/dryad.1ns1rn8ts
title: Data from: Disturbance history is a key driver of tree lifespan in temperate primary forests

description: AIMS We examined differences in lifespan among the dominant tree species
 (spruce (Picea abies (L.) H. Karst.), fir (Abies alba Mill.), beech (Fagus
 sylvatica L.), and maple (Acer pseudoplatanus L.)) across primary mountain
 forests of Europe. We ask how disturbance history, lifetime growth
 patterns, and environmental factors influence lifespan. LOCATIONS Balkan
 mountains, Carpathian mountains, Dinaric mountains. METHODS Annual ring
 widths from 20,600 cores from primary forests were used to estimate tree
 life spans, growth trends, and disturbance history metrics. Mixed models
 were used to examine species-specific differences in lifespan (i.e.
 defined as species-specific 90th percentiles of age distributions), and
 how metrics of radial growth, disturbance parameters, and selected
 environmental factors influence lifespan. RESULTS While only a few beech
 trees surpassed 500 years, individuals of all four species were older than
 400 years. There were significant differences in lifespan among the four
 species (beech &gt; fir &gt; spruce &gt; maple), indicating
 life history differentiation in lifespan. Trees were less likely to reach
 old age in areas affected by more severe disturbance events, whereas
 individuals that experienced periods of slow growth and multiple episodes
 of suppression and release were more likely to reach old age. Aside from a
 weak but significant negative effect of vegetation season temperature on
 fir and maple lifespan, no other environmental factors included in the
 analysis influenced lifespan. CONCLUSIONS Our results indicate
 species-specific biological differences in lifespan, which may play a role
 in facilitating tree species coexistence in mixed temperate forests.
 Finally, natural disturbances regimes were a key driver of lifespan, which
 could have implications for forest dynamics if regimes shift under global
 change.
description: This
 study was conducted in primary temperate mountain forests of the
 Carpathian Mountains and the Balkan peninsula, spanning from
 beech-dominated and mixed forests (hereafter referred to as beech forests)
 at lower elevations to spruce-dominated forests at higher elevations. The
 dataset used for this study is a part of the REMOTE network
 (www.remoteforests.org), which is focused on surveying remaining tracts of
 primary forest landscapes in Europe and long-term study of their dynamics.
 The plot network has a hierarchical sampling scheme, with plots located
 within stands, and multiple stands organized in larger landscapes. For
 this study, we split the dataset into 11 landscapes, based on geographic
 location and forest type. They include 7 beech-dominated landscapes (i.e.
 Albania, Bulgaria, Croatia, Central Slovakia beech, Eastern Slovakia
 beech, Northern Romania beech, and Southern Romania beech) and 4
 spruce-dominated landscapes (i.e. Central Slovakia spruce, Ukraine spruce,
 Northern Romania spruce, and Southern Romania spruce). The landscapes
 comprise a total of 35 spruce-dominated stands and 33 beech-dominated
 stands. 971 plots were analysed in total. The lifespan
 of 20600 tree cores was determined following standard dendrochronological
 procedures. All tree cores that had more than 20 missing rings to the
 pith, as well as the cores with estimated age of less than 50 years were
 excluded from further studies. Disturbance chronologies were derived from
 temporal patterns in inter-annual tree growth. We used the original
 approach of Lorimer and Frelich (1989), in which each core is screened for
 (1) abrupt, sustained increases in radial growth (i.e releases) and (2)
 rapid early growth rates (i.e. gap-recruited trees), both of which provide
 indirect evidence of mortality of a former canopy tree. The events were
 aggregated at the plot level by smoothing and detecting peaks in their
 distributions. Ultimately we used the severity and timing of the most
 severe event on the plot as a proxy of past disturbance. Latitude, slope,
 aspect (transformed to northness), and the average temperature of the
 vegetation season (by downscaling the Worldclim gridded data (Fick and
 Hijmans, 2017) for the period 1970–2000) were used as proxies for
 environmental conditions. For each core also the number of releases,
 minimum 10-year growth, maximum 10-year growth and early growth (average
 growth rate in the first 50 years) were used as proxies of individual
 growth. Densities of the oldest trees were calculated as densities of
 trees ≥ species-specific 90th percentile of age on the stand level, while
 the share of the oldest canopy trees in the canopies was also calculated
 on the stand level as the share of trees ≥ species-specific 90th
 percentile of age that were characterized as canopy trees among all the
 canopy trees detected on the plots.
description: The
 dataset contains the age data resulting from dendrochronological analyses.
 It is comprised of three tables related to tree lifespan in the study
 area: (Data90all), (Densities), and (Share_old_canopy_trees).
 Individual
 core (tree) data is included in the first table (Data90all). Each row
 shows the data for the specific tree (core). Each tree is characterized by
 a unique “treeid”. “plot_id” is the identifier of the plot, “stand” is the
 identifier of the stand, “landscape” is the identifier of the landscape,
 “foresttype” is the identifier of the respective forest type, “species”
 marks the tree species, and “age” its age. “over90q” marks whether the
 tree was ≥ species-specific 90th percentile of age in that case the value
 is 1, while in the case the tree was &lt; species-specific 90th
 percentile of age 0 was assigned. “n_release” marks the number of release
 events identified in the respective tree chronology. “lat” marks the
 latitude [˚] of the respective plot, “lng” marks the longitude [˚] of the
 respective plot, and “altitude_m” marks the altitude [m] of the respective
 plot. “incr_50” represents the average growth of the tree in the first 50
 years [mm/year], while “growth_max” represents maximum 10-year running
 mean of annual growth rates [mm/year], and “growth_min” represents minimum
 10-year running mean of annual growth rates [mm/year]. “dbh_mm” marks the
 tree’s DBH [mm]. “slope” represents the slope [˚] of the respective plot,
 while “aspect” represents the aspect [˚] of the respective plot.
 “northness” is cosine transformed aspect. “temp_mean_vegetseason”
 represents the average temperature of the vegetation season [˚C] on the
 respective plot. “disturbance_severity” marks the severity of the most
 severe disturbance event [% of canopy removed] on the respective plot,
 while “disturbance_year” marks the year of this event. “Pairplot” marks
 the respective pair of plots. The densities
 of the trees ≥ species-specific 90th percentile of age on the stand level
 are included in the second table (Densities). Each row represents the
 density of the ≥ species-specific 90th percentile of age of a particular
 species in a particular stand. “landscape” marks the respective landscape,
 “stand” marks the respective stand, while “species” marks the particular
 species which the density on the stand level stands for. “standsize”
 represents the size of the sampled area [m<sup>2</sup>] in the
 particular stand. “n_stand” represents the number of trees of a particular
 species ≥ species-specific 90th percentile of age [n/ha] in the particular
 stand. “density” stands for the density of the trees of a particular
 species ≥ species-specific 90th percentile of age [n/ha] in the particular
 stand, while “stand _density” represents the cumulative density of all the
 trees ≥ species-specific 90th percentile of age [n/ha] in the particular
 stand. The final table (Share_old_canopy_trees)
 represents the shares of the trees ≥ species-specific 90th percentile of
 age in the canopy layer. “landscape” marks the respective landscape,
 “stand” marks the respective stand, while “species” marks the particular
 species which the density on the stand level stands for. “n_total” stands
 for all the canopy trees in the particular stand, while “n” marks the
 number of canopy trees ≥ species-specific 90th percentile of age in the
 respective stand. “share” stands for the share of the trees of a
 particular species ≥ species-specific 90th percentile of age in the canopy
 layer [%] in the particular stand, while “stand _share” represents the
 cumulative share of all the trees ≥ species-specific 90th percentile of
 age in the canopy [%] in the particular stand.