DOI: 10.5061/dryad.b5mkkwhp7
title: Data from: Space-for-time substitution misleads projections of plant community and stand-structure development after disturbance in a slow-growing environment

description: Understanding and projecting ecosystem dynamics is a key goal for both
 basic science and applied ecosystem management. In ecosystems dominated by
 long-lived organisms such as forests, space-for-time substitutions (SFT)
 inferring temporal development from observations of study objects
 differing in age across space at a given time, also called
 chronosequences, are widely used as an alternative approach for long-term
 monitoring, in particular, to understand forest dynamics after
 stand-replacing disturbances. Uncertainties and challenges of SFT
 substitution, however, arise from violations of the underlying assumption
 that everything but time since disturbance is identical among the spatial
 sampling sites. Direct comparisons between true time series and SFT
 substitutions are still surprisingly rare. I resampled a 20-year-old SFT
 substitution study to check if this method accurately projects vegetation
 changes after major disturbances in primary subalpine conifer forests and
 to evaluate its conclusions for forest management. Two decades and a
 spatial scale of about 600 km² constitute spatial and temporal conditions
 for which little empirical evidence for the validity of SFT substitution
 exists. SFT suggested a strong shift away from old-growth plant community
 compositions after clearcutting with, misleadingly, no trend back over two
 decades. True temporal development, however, differed significantly from
 this expectation as it showed a directional trend back towards old-growth
 plant community compositions after the initial displacement. Compositional
 recovery is predicted to take 100-200 years in the studied ecosystem.
 Accordingly, several late seral forest floor herbs and bryophytes were
 still missing completely even 50 years after
 clearcutting. Non-constant climate, species pools, and management
 actions compromise the ability to reliably project temporal dynamics in
 plant community composition and stand structure by space-for-time
 substitutions, likely also for other scenarios than the studied subalpine
 conifer forests after stand-replacing disturbance. Long-term monitoring
 therefore is indispensable for understanding ecosystem dynamics, in
 particular in slow-growing and stressful environments. Management needs to
 consider the slow regeneration in its planning of rotation times and is
 advised to monitor and retain species indicative of old-growth conditions
 at the landscape level.
description: This dataset contains plot-level information and plant species
 occurrences from 48 plots from a subalpine, boreal forest region in
 southern British Columbia, Canada, sampled as a chronosequence of primary
 forests and development after stand-replacing disturbance (clearcutting,
 with young and old clear-cuts differing by 20 years in time). Initial
 sampling took place in 2003, and resampling of all plots took place in
 2023. The 20 years of true temporal development can therefore be compared
 to a 20-year chronosequence (space for time) approach. See the main
 publication for more details.
description: # Data from: Space-for-time substitution misleads projections of plant
 community and stand-structure development after disturbance in a
 slow-growing environment [https://doi.org/10.5061/dryad.b5mkkwhp7
 ](https://doi.org/10.5061/dryad.b5mkkwhp7) ## Description of the data and
 file structure "Plot" runs from 1-48, with each plot occurring
 twice for being sampled in two different "Sampling Years", i.e.,
 2003 and 2023. Plot size is 100m². "Disturbance type" is either
 "clearcut", "fire", or "windthrow".
 Disturbance type "no" indicates the absence of stand-replacing
 disturbances for &gt; 100 years. "Latitude" and
 "Longitude" are provided in decimal degrees with negative
 longitudes indicating west of Greenwich. "Altitude" is elevation
 above sea level in meters. "Tree canopy cover" and
 "Deadwood cover" are visual estimations from the ground with
 possible ranges from 0% to 100%. "Species richness" includes all
 bryophytes and vascular plants except for epiphytes with aboveground cover
 in the respective plot. "Basal area" is the tree stem area at
 1.3 m height, calculated from measurements of the circumference of all
 trees reaching at least this height. Unit is m² per ha. "Tree
 count" is the number of individuals irrespective of their size,
 meaning seedlings to full-grown trees. The number of trees smaller than
 1.3 m is missing for the initial sampling of the reference_2003 stands
 (rows 34-49, plots 33-48 for the sampling year 2003, where the numbers
 represent only the trees &gt;1.3m tall), but available for all other
 stands and times. Columns O to EQ contains the presence/absence
 information of all species and each plot. Species are abbreviated to the
 first three letters of their genus names and species epitaphs, see below
 for full species names and species abbreviations. All specimens were
 identified at the genus level, but some specimens were not successfully
 identified at the species level. If, based on leaf and stem shape and
 morphology, those specimens clearly differed from all other identified
 species of the same genera, those other species were kept and the
 unidentified species treated as another species (*Brachythecium* spec,
 *Carex* spec, *Cirsium* spec, *Hieracium* spec, *Pyrola* spec, *Salix*
 spec (even twice), *Vaccinium* spec, *Viola* spec). If the unidentified
 species did not clearly differ from other identified species of the same
 genera or if there were no other species identified in that genera at all,
 all specimens were treated as one species (*Antennaria* spec, *Arnica*
 spec, *Aster* spec, *Dicranum* spec, *Eurhynchium* spec, *Listera* spec,
 *Plagiothecium* spec). With regards to the trees, abundance by species and
 diameter at 1.3 m height (DBH) were documented. Species names
 (nomenclature according to Schoch et al., 2020): | Species | Growth form |
 Abbreviation | |
 :---------------------------------------------------------------- |
 :---------- | :----------- | | Abies lasiocarpa Nutt. | tree | Abilas | |
 Actaea rubra (Aiton) Willd. | herb | Actrub | | Agrostis scabra Willd. |
 graminoid | Agrsca | | Alnus alnobetula (Ehrh.) K.Koch | shrub | Alnaln |
 | Alnus incana Moench | shrub | Alninc | | Anaphalis margaritacea (L.)
 Benth. & Hook. f. | herb | Anamar | | Antennaria Gaertn. | herb |
 Antspec | | Arnica L. | herb | Arnspe | | Aster L. | herb | Astspe | |
 Athyrium filix-femina (L.) Roth | fern | Athfil | | Aulacomnium palustre
 (Hedw.) Schwaegr. | bryophyte | Aulpal | | Barbilophozia lycopodioides
 (Wallr.) Loeske | bryophyte | Barlyc | | Brachythecium albicans (Hedw.)
 Schimp. | bryophyte | Braalb | | Brachythecium erythrorrhizon Schimp. |
 bryophyte | Braery | | Brachythecium hylotapetum B.L.Higinb. &
 N.L.Higinb. | bryophyte | Brahyl | | Brachythecium salebrosum (Hoffm. ex
 F.Weber & D.Mohr) Schimp. | bryophyte | Brasal | | Brachythecium
 Schimp. | bryophyte | Braspe | | Brewerimitella breweri (A.Gray) R.A.Folk
 & Y.Okuyama | herb | Mitbre | | Bromus vulgaris Shear | graminoid |
 Brovul | | Calamagrostis canadensis (Michx.) P.Beauv. | graminoid | Calcan
 | | Carex bebbii Olney ex Fernald | graminoid | Carbeb | | Carex canescens
 L. | graminoid | Carcan | | Carex L | graminoid | Carspe | | Carex
 magellanica Lam. | graminoid | Carmag | | Carex rossii Boott | graminoid |
 Carros | | Cassiope mertensiana (Bong.) G.Don | shrub | Casmer | |
 Ceratodon purpureus (Hedw.) Brid. | bryophyte | Cerpur | | Chamaenerion
 angustifolium (L.) Scop. | herb | Chaang | | Chimaphila umbellata
 W\.P.C.Barton | shrub | Chiumb | | Cirsium Mill. | herb | Cirspe | |
 Cirsium vulgare (Savi) Ten. | herb | Cirvul | | Clintonia uniflora
 (Menzies ex Schult. & Schult.f.) Kunth | herb | Cliuni | | Cornus
 canadensis L. | herb | Corcan | | Dicranum Hedw. | bryophyte | Dicspe | |
 Diphasiastrum complanatum (L.) Holub | herb | Dipcom | | Dryopteris
 expansa (C.Presl) Fraser-Jenk. & Jermy | fern | Dryexp | | Elymus
 glaucus Buckley | graminoid | Elygla | | Epilobium ciliatum Raf. | herb |
 Epilcil | | Equisetum arvense L. | herb | Equarv | | Eurhynchium Bruch
 & Schimp. | bryophyte | Eurspe | | Festuca occidentalis Hook. |
 graminoid | Fesocc | | Fragaria virginiana Mill. | herb | Fravir | |
 Funaria hygrometrica Hedw. | bryophyte | Funhyg | | Galium triflorum
 Michx. | herb | Galtri | | Goodyera oblongifolia Raf. | herb | Gooobl | |
 Gymnocarpium dryopteris (L.) Newman | fern | Gymdry | | Hieracium
 albiflorum Hook. | herb | Hiealb | | Hieracium L. | herb | Hiespe | |
 Hylocomiadelphus triquetrus (Hedw.) Ochyra & Stebel | bryophyte |
 Hyltri | | Lactuca canadensis L. | herb | Laccan | | Larix occidentalis
 Nutt. | tree | Larocc | | Leucanthemum vulgare Lam. | herb | Leuvul | |
 Lilium columbianum Leichtlin | herb | Lilcol | | Linnaea borealis L. |
 shrub | Linbor | | Listera R.Br. | herb | Lisspe | | Lonicera involucrata
 (Richardson) Banks ex Spreng. | shrub | Loninv | | Lonicera utahensis S.
 Watson | shrub | Lonuta | | Lupinus arcticus S.Watson | herb | Luparc | |
 Luzula parviflora Desv. | graminoid | Luzpar | | Maianthemum racemosum
 Link | herb | Mairac | | Marchantia polymorpha L. | bryophyte | Marpol | |
 Mnium spinulosum Bruch & Schimp. | bryophyte | Mnispi | | Neottia
 cordata Rich. | herb | Neocor | | Orthilia secunda (L.) House | herb/shrub
 | Ortsec | | Osmorhiza berteroi DC. | herb | Osmber | | Packera pseudaurea
 (Rydb.) W\.A.Weber & Á.Löve | herb | Pacpse | | Parnassia fimbriata
 K.D.Koenig | herb | Parfim | | Paxistima myrsinites (Pursh) Raf. | shrub |
 Paxmyr | | Pedicularis bracteosa Benth. | herb | Pedbra | | Pedicularis
 racemosa Douglas ex Benth. | herb | Pedrac | | Philonotis fontana (Hedw.)
 Brid. | bryophyte | Phifon | | Picea glauca (Moench) Voss x engelmannii
 Engelm. | tree | Picgla | | Pilosella aurantiaca (L.) F.W\.Schultz &
 Sch.Bip. | herb | Hieaur | | Pinus contorta var. latifolia Engelm. | tree
 | Pincon | | Pinus monticola Douglas ex D. Don | tree | Pinmon | |
 Plagiomnium affine (Blandow ex Funck) T.J.Kop. | bryophyte | Plaaff | |
 Plagiothecium Bruch & Schimp. | bryophyte | Plaspe | | Platanthera
 aquilonis Sheviak | herb | Plaaqu | | Pleurozium schreberi (Brid.) Mitt. |
 bryophyte | Plesch | | Polytrichum formosum Hedw. | bryophyte | Polfor | |
 Polytrichum juniperinum Hedw. | bryophyte | Poljun | | Polytrichum
 piliferum Hedw. | bryophyte | Polpil | | Populus balsamifera L. | tree |
 Popbal | | Populus tremuloides Michx. | tree | Poptre | | Pseudotsuga
 menziesii (Mirb.) Franco | tree | Psemen | | Ptilium crista-castrensis
 (Hedw.) De Not. | bryophyte | Pticri | | Ptychostomum capillare (Hedw.)
 D.T.Holyoak & N.Pedersen | bryophyte | Ptycap | | Pyrola asarifolia
 Michx. | herb | Pyrasa | | Pyrola chlorantha Sw. | herb | Pyrchl | |
 Pyrola L. | herb | Pyrspe | | Racomitrium lanuginosum (Hedw.) Brid. |
 bryophyte | Raclan | | Ranunculus uncinatus D. Don ex G. Don | herb |
 Ranunc | | Rhizomnium punctatum (Hedw.) T.J.Kop. | bryophyte | Rhipun | |
 Rhododendron albiflorum Hook. | shrub | Rhoalb | | Rhododendron
 menziesii Craven | shrub | Menfer | | Rhytidiadelphus squarrosus (Hedw.)
 Warnst. | bryophyte | Rhysqu | | Ribes lacustre (Pers.) Poir. | shrub |
 Riblac | | Rubus idaeus L. | shrub | Rubida | | Rubus parviflorus Nutt. |
 shrub | Rubpar | | Rubus pedatus Sm. | herb/shrub | Rubped | | Salix L. |
 shrub | Salsp1 | | Salix L. | shrub | Salsp3 | | Salix scouleriana Barratt
 ex Hook. | shrub | Salsco | | Sambucus racemosa L. | shrub | Samrac | |
 Senecio triangularis Hook. | herb | Sentri | | Sorbus scopulina Greene |
 shrub | Sorsco | | Sorbus sitchensis M. Roem. | shrub | Sorsit | |
 Spinulum annotinum (L.) A.Haines | herb | Spiann | | Spiraea betulifolia
 Pall. | shrub | Spibet | | Stellaria umbellata Turcz. ex Kar. & Kir. |
 herb | Steumb | | Streptopus amplexifolius (L.) DC. | herb | Streamp | |
 Streptopus lanceolatus Reveal | herb | Strelan | | Taraxacum officinale
 G.H. Weber ex Wiggers | herb | Taroff | | Tellima grandiflora Douglas ex
 Lindl. | herb | Telgra | | Thalictrum occidentale A.Gray | herb | Thaocc |
 | Thuja plicata Donn ex D. Don | tree | Thupli | | Tiarella trifoliata
 var. unifoliata (Hook.) Kurtz | herb | Tiatri | | Torreyochloa pallida
 var. pauciflora (J.S.Presl) J.I.Davis | graminoid | Torpau | | Trifolium
 hybridum L. | herb | Trihyb | | Trillium ovatum Pursh | herb | Triova | |
 Trisetum cernuum subsp. canescens (Buckley) Calder & Roy L.Taylor |
 graminoid | Triscan | | Trollius albiflorus (A.Gray) Rydb. | herb | Troalb
 | | Tsuga heterophylla Sarg. | tree | Tsuhet | | Vaccinium L. | shrub |
 Vacspe | | Vaccinium membranaceum Dougl. ex Torr. | shrub | Vacmem | |
 Vaccinium ovalifolium Sm. | shrub | Vacova | | Vaccinium scoparium Leiberg
 ex Coville | shrub | Vacsco | | Valeriana sitchensis Bong. | herb | Valsit
 | | Veratrum viride Aiton | herb | Vervir | | Veronica beccabunga L. |
 herb | Verbec | | Viola glabella Nutt. | herb | Viogla | | Viola
 orbiculata (A.Gray) Geyer ex B.D.Jacks. | herb | Vioorb | | Viola L. |
 herb | Viospe |