Spatial patterns can inform us of forest recruitment, mortality, and tree interactions through time and disturbance. Specifically, successional trajectories of self-thinning and heterospecific negative density dependence can be interpreted from the spatial arrangement of forest stems. We conducted a 50-year spatial analysis of a forest undergoing succession at the ecotone of the southwestern Canadian boreal forest. The forest progressed from early to late sere and experienced repeated severe droughts, forest tent caterpillar outbreaks (Malacosoma disstria), as well as the outbreak of bark beetles. Cumulatively, the forest lost 70% of stems due to natural succession and a combination of disturbance events. Here, we describe spatial patterns displaying signals of successional self-thinning, responses to disturbance, and changes in patterns of density dependence across 50 years. Forest succession and disturbance events resulted in fluctuating patterns of density-dependent mortality and recruitment that persisted into late seral stages. The combined effects of conspecific and heterospecific density-dependent effects on mortality and recruitment resulted in near-spatial equilibrium over the study period. However, the strength and direction of these demographic and spatial processes varied in response with time and disturbance severity. The outbreak of forest tent caterpillar, pronounced drought, and bark beetles combined to reduce stand aggregation and promote a spatial equilibrium. Density-dependent processes of competition and facilitation changed in strength and direction with succession of the plot and in combination with disturbance. Together these results reinforce the importance of successional stage and disturbance to spatial patterns.
This is a preview of subscription content, access via your institution.
Buy single article
Instant access to the full article PDF.
Price excludes VAT (USA)
Tax calculation will be finalised during checkout.
Aakala T, Fraver S, Palik BJ, D’Amato AW (2012) Spatially random mortality in old-growth red pine forests of northern Minnesota. Can J For Res 42:899–907. https://doi.org/10.1139/x2012-044
Baddeley A, Rubak E, Turner R (2016) Spatial point patterns: methodology and applications with R. J Stat Softw. https://doi.org/10.18637/jss.v075.b02
Bergeron Y, Chen HYH, Kenkel NC, Leduc AL, Macdonald SE (2014) Boreal mixedwood stand dynamics: ecological processes underlying multiple pathways. For Chron 90:202–213. https://doi.org/10.5558/tfc2014-039
Birch JD, Lutz JA, Hogg EH, Simard SW, Pelletier R, LaRoi GH, Karst J (2019) Decline of an ecotone forest: 50 years of demography in the southern boreal forest. Ecosphere 10(4):e02698. https://doi.org/10.1002/ecs2.2698
Brassard BW, Chen HYH (2006) Stand structural dynamics of North American boreal forests. Crit Rev Plant Sci 25:115–137. https://doi.org/10.1080/07352680500348857
Buck JR, St. Clair SB (2014) Stand composition, proximity to overstory trees and gradients of soil moisture influence patterns of subalpine fir seedling emergence and survival. Plant Soil 381:61–70. https://doi.org/10.1007/s11104-014-2094-9
Cale WG, Henebry GM, Yeakley JA (1989) Inferring process from pattern in natural communities. Bioscience 39:600–605. https://doi.org/10.2307/1311089
Chen HYH, Luo Y (2015) Net aboveground biomass declines of four major forest types with forest ageing and climate change in western Canada’s boreal forests. Glob Change Biol 21:3675–3684
Cornett MW, Reich PB, Puettmann KJ (1997) Canopy feedbacks and microtopography regulate conifer seedling distribution in two Minnesota conifer-deciduous forests. Écoscience 4:353–364
Das A, Battles J, Stephenson NL, van Mantgem PJ (2011) The contribution of competition to tree mortality in old-growth coniferous forests. For Ecol Manag 261:1203–1213. https://doi.org/10.1016/j.foreco.2010.12.035
DeRose RJ, Long JN (2012) Factors influencing the spatial and temporal dynamics of Engelmann spruce mortality during a spruce beetle outbreak on the Markagunt Plateau, Utah. For Sci 58(1):1–14
DeRose RJ, Bekker MF, Long JN (2017) Traumatic resin ducts as indicators of bark beetle outbreaks. Can J For Res 47:1168–1174
Després T, Vítková L, Bače R, Čada V, Janda P, Mikoláš M, Schurman JS, Trotsiuk V, Svoboda M (2017) Past disturbances and intraspecific competition as drivers of spatial pattern in primary spruce forests. Ecosphere 8:e02037. https://doi.org/10.1002/ecs2.2037
Diffenbaugh NS, Field CB (2013) Changes in ecologically critical terrestrial climate conditions. Science 341:486–492. https://doi.org/10.1126/science.1237123
Environment and Climate Change Canada (2017) Historical climate data: climate stations 3012205 and 3012216—concatenated, 1961 to 2017 [Data set]. https://climate.weather.gc.ca/historical_data/search_historic_data_e.html. Accessed 2 Feb 2017
Flora of North America Editorial Committee (eds) (1993) Flora of North America North of Mexico, vol 19. New York, Oxford
Fraver S, D’Amato AW, Bradford JB, Jonsson BG, Jönsson M, Esseen PA (2014) Tree growth and competition in an old-growth Picea abies forest of boreal Sweden: influence of tree spatial patterning. J Veg Sci 25:374–385. https://doi.org/10.1111/jvs.12096
Furniss TJ, Larson AJ, Lutz JA (2017) Reconciling niches and neutrality in a subalpine temperate forest. Ecosphere 8:e01847. https://doi.org/10.1002/ecs2.1847
Gendreau-Berthiaume B, Macdonald SE, Stadt JJ (2016) Extended density-dependent mortality in mature conifer forests: causes and implications for ecosystem management. Ecol Appl 26:1486–1502
Greenwood DL, Weisberg PJ (2008) Density-dependent tree mortality in pinyon-juniper woodlands. For Ecol Manag 255:2129–2137. https://doi.org/10.1016/j.foreco.2007.12.048
Hogg EH, Brandt JP, Kochtubajda B (2002a) Growth and dieback of aspen forests in northwestern Alberta, Canada, in relation to climate and insects. Can J For Res 32:823–832
Hogg EH, Hart M, Lieffers VJ (2002b) White tree rings formed in trembling aspen saplings following experimental defoliation. Can J For Res 32:1929–1934
Hogg EH, Michaelian M, Hook TI, Undershultz ME (2017) Recent climatic drying leads to age- independent growth reductions of white spruce stands in western Canada. Glob Change Biol 23:5297–5308
Horner GJ, Baker PJ, Mac Nally R, Cunningham SC, Thomson JR, Hamilton F (2009) Mortality of developing floodplain forests subjected to a drying climate and water extraction. Glob Change Biol 15:2176–2186. https://doi.org/10.1111/j.1365-2486.2009.01915.x
Johnstone JF (2005) Effects of aspen (Populus tremuloides) sucker removal on postfire conifer regeneration in central Alaska. Can J For Res 35:483–486. https://doi.org/10.1139/x04-171
Kenkel NC (1988) Pattern of self-thinning in Jack Pine: testing the random mortality hypothesis. Ecology 69:1017–1024. https://doi.org/10.2307/1941257
Kenkel N, Foster C, Caners R, Lastra R, Walker D (2006) Spatial and temporal patterns of white spruce recruitment in two boreal mixedwood stands. Duck Mountains, Manitoba
Klos RJ, Wang GG, Bauerle WL, Rieck JR (2009) Drought impact on forest growth and mortality in the southeast USA: an analysis using Forest Health and Monitoring data. Ecol Appl 19:699–708
Linares JC, Camarero JJ, Carreira JA (2010) Competition modulates the adaptation capacity of forests to climatic stress: insights from recent growth decline and death in relict stands of the Mediterranean fir Abies pinsapo. J Ecol 98:592–603. https://doi.org/10.1111/j.1365-2745.2010.01645.x
Lutz JA (2015) The evolution of long-term data for forestry: large temperate research plots in an era of global change. Northwest Sci 89(3):255–269
Lutz JA, Larson AJ, Furniss TJ, Donato DC, Freund JA, Swanson ME, Bible KJ, Chen J, Franklin JF (2014) Spatially nonrandom tree mortality and ingrowth maintain equilibrium pattern in an old-growth Pseudotsuga–Tsuga forest. Ecology 95:2047–2054. https://doi.org/10.1890/14-0157.1
Metsaranta JM, Lieffers VJ (2008) A fifty-year reconstruction of annual changes in the spatial distribution of Pinus banksiana stands: does pattern fit competition theory? Plant Ecol 199:137–152. https://doi.org/10.1007/s11258-008-9419-9
Michaelian M, Hogg EH, Hall RJ, Arsenault E (2011) Massive mortality of aspen following severe drought along the southern edge of the Canadian boreal forest: aspen mortality following severe drought. Glob Change Biol 17:2084–2094
Moeur M (1993) Characterizing spatial patterns of trees using stem-mapped data. For Sci 39:756–775
Peterson CJ, Squiers ER (1995) Competition and succession in an Aspen–White-Pine forest. J Ecol 83:449. https://doi.org/10.2307/2261598
R Core Team (2018) R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. Version 3.4.4. https://www.R-project.org/
Teste FP, Simard SW, Durall DM (2009) Role of mycorrhizal networks and tree proximity in ectomycorrhizal colonization of planted seedlings. Fungal Ecol 2:21–30. https://doi.org/10.1016/j.funeco.2008.11.003
Turner MG, Baker WL, Peterson CJ, Peet RK (1998) Factors influencing succession: lessons from large, infrequent natural disturbances. Ecosystems 1:511–523. https://doi.org/10.1007/s100219900047
Weiner J, Damgaard C (2006) Size-asymmetric competition and size-asymmetric growth in a spatially explicit zone-of-influence model of plant competition. Ecol Res 21:707–712. https://doi.org/10.1007/s11284-006-0178-6
Wickham H (2011) The split-apply-combine strategy for data analysis. J Stat Softw 40:1–29
Wickham H (2016) ggplot2: elegant graphics for data analysis. Springer, New York
Wiegand T, Moloney KA (2004) Rings, circles, and null-models for point pattern analysis in ecology. Oikos 104:209–229
Worrall JJ, Rehfeldt GE, Hamann A, Hogg EH, Marchetti SB, Michaelian M, Gray LK (2013) Recent declines of Populus tremuloides in North America linked to climate. For Ecol Manag 299:35–51. https://doi.org/10.1016/j.foreco.2012.12.033
Zhang J, Huang S, He F (2015) Half-century evidence from western Canada shows forest dynamics are primarily driven by competition followed by climate. Proc Natl Acad Sci 112:4009–4014. https://doi.org/10.1073/pnas.1420844112
We acknowledge Jerry Shaw for his work as a volunteer digitizing the 1967–1997 data. E. H. Hogg provided feedback on the manuscript and analysis. Chloe Christenson, Evan Fellrath, Marc La Flèche, Dana Hopfauf, Paul Metzler, and Joshua Wasyliw assisted with stem mapping in May 2017. Tucker Furniss assisted with spatial analysis. Lee Foote granted access to the GLR plot in the University of Alberta Botanical Gardens. Funding was provided by the Alberta Conservation Association Grants for Biodiversity to Joseph Birch, and a Natural Sciences and Engineering Research Council of Canada Discovery Grant to Justine Karst.
Funding was provided by Canadian Network for Research and Innovation in Machining Technology, Natural Sciences and Engineering Research Council of Canada (RGPIN 2017-03813), Alberta Conservation Association.
Conflict of interest
The authors declare that they have no conflict of interest.
Communicated by Marie-Josée Fortin.
Electronic supplementary material
Below is the link to the electronic supplementary material.
About this article
Cite this article
Birch, J.D., Lutz, J.A., Simard, S.W. et al. Density-dependent processes fluctuate over 50 years in an ecotone forest. Oecologia 191, 909–918 (2019). https://doi.org/10.1007/s00442-019-04534-6