Management implications of varying gap detection height thresholds and other canopy dynamics processes in temperate deciduous forests

Abstract Gap dynamics is the main process by which forest renewal happens in many forest biomes in the world. Under the classical gap dynamics model, only canopy gaps are considered as a dynamic zone. It is also assumed that gapless canopy height change is either uncommon or unimportant for forest dynamics, even though its frequency has never been quantified. In the temperate deciduous forest biome of Quebec, Canada, forest management uses selection cutting to emulate gap dynamics, but little is known about the differences in canopy dynamics between unmanaged and managed forests. Here, we investigated five canopy height change processes: three generating positive height change (canopy growth, gap closure and gap filling) and two generating negative height change (gap creation and canopy height erosion) using multi-temporal LiDAR data in unmanaged and managed (by partial cutting) forests at different periods during the last 24 years. Canopy height erosion, which is canopy height reduction without gap formation, was very common in all studied forests, whatever the gap detection height thresholds used. This canopy process was often more frequent than new canopy gaps and as important in terms of canopy volume reduction. Gap closure rates suggest that canopy gaps will remain more frequent in managed forests 30 years after cuts compared to unmanaged forests. Our results show that it will take at least 30 years after cuts for natural canopy dynamics to recover. We also show that measurements of canopy dynamics processes are sensitive to canopy gap detection height thresholds. This sensitivity is clearly limiting the reproducibility and the comparability of studies in gap ecology.

[1]  M. Lechowicz,et al.  Impact of a major ice storm on an old-growth hardwood forest , 2001 .

[2]  J. Dalling,et al.  Spatial scale and sampling resolution affect measures of gap disturbance in a lowland tropical forest: implications for understanding forest regeneration and carbon storage , 2014, Proceedings of the Royal Society B: Biological Sciences.

[3]  Michael Bock,et al.  System for Automated Geoscientific Analyses (SAGA) v. 2.1.4 , 2015 .

[4]  Steven P. Hamburg,et al.  Effects of an intense ice storm on the structure of a northern hardwood forest , 2002 .

[5]  P. Duinker,et al.  Old-growth Forests: Anatomy of a Wicked Problem , 2011 .

[6]  Marilou Beaudet,et al.  Comparing composition and structure in old-growth and harvested (selection and diameter-limit cuts) northern hardwood stands in Quebec , 2005 .

[7]  M. Lowman,et al.  Subcanopy gaps in temperate and tropical forests , 1997 .

[8]  Frederick J. Swanson,et al.  OVERVIEW OF THE USE OF NATURAL VARIABILITY CONCEPTS IN MANAGING ECOLOGICAL SYSTEMS , 1999 .

[9]  P. Reich,et al.  Canopy gap size influences niche partitioning of the ground-layer plant community in a northern temperate forest , 2013 .

[10]  Lawerence S. Barden.  Repeatability in Forest Gap Research: Studies in the Great Smoky Mountains , 1989 .

[11]  G. Asner,et al.  Long-term fragmentation effects on the distribution and dynamics of canopy gaps in a tropical montane forest , 2015 .

[12]  E. W. Jones.  THE STRUCTURE AND REPRODUCTION OE THE VIRGIN EOREST OE THE NORTH TEMPERATE ZONE , 1945 .

[13]  Charles D. Canham,et al.  An Index For Understory Light Levels in and Around Canopy Gaps , 1988 .

[14]  N. Brokaw,et al.  The definition of treefall gap and its effect on measures of forest dynamics. , 1982 .

[15]  S. Magnussen,et al.  Stand-level wind damage can be assessed using diachronic photogrammetric canopy height models , 2017, Annals of Forest Science.

[16]  J. Mccarthy,et al.  Gap dynamics of forest trees: A review with particular attention to boreal forests , 2001 .

[17]  A. Watt,et al.  Pattern and process in the plant community , 1947 .

[18]  D. Lieberman,et al.  Forests are Not Just Swiss Cheese: Canopy Stereogeometry of Non‐Gaps in Tropical Forests , 1989 .

[19]  M. Lechowicz,et al.  Ice Storm Damage and Early Recovery in an Old-Growth Forest , 2001, Environmental monitoring and assessment.

[20]  S. Bédard,et al.  The Irregular Shelterwood System: Review, Classification, and Potential Application to Forests Affected by Partial Disturbances , 2009 .

[21]  Steward T. A. Pickett,et al.  Chapter 2 – Disturbance Regimes in Temperate Forests , 1985 .

[22]  J. R. Runkle.  Twenty-four years of change in an old Tsuga canadensis woods affected by beech bark disease1 , 2005 .

[23]  Frédérik Doyon,et al.  Effects of strip and single-tree selection cutting on birds and their habitat in a southwestern Quebec northern hardwood forest , 2005 .

[24]  Benoît St-Onge,et al.  Spatially explicit characterization of boreal forest gap dynamics using multi-temporal lidar data , 2008 .

[25]  Z. Majcen.  Historique des coupes de jardinage dans les forêts inéquiennes au Québec , 1994 .

[26]  S. Carpenter,et al.  Resilience indicators: prospects and limitations for early warnings of regime shifts , 2015, Philosophical Transactions of the Royal Society B: Biological Sciences.

[27]  John P. Caspersen,et al.  Seedling recruitment in a northern temperate forest: the relative importance of supply and establishment limitation , 2005 .

[28]  James R. Runkle,et al.  PATTERNS OF DISTURBANCE IN SOME OLD-GROWTH MESIC FORESTS OF EASTERN NORTH AMERICA' , 1982 .

[29]  C. Messier,et al.  Analysis of deciduous tree species dynamics after a severe ice storm using SORTIE model simulations , 2005 .

[30]  Marilou Beaudet,et al.  Effect of a major canopy disturbance on the coexistence of Acer saccharum and Fagus grandifolia in the understorey of an old‐growth forest , 2007 .

[31]  J. R. Runkle.  Thirty-two years of change in an old-growth Ohio beech-maple forest. , 2013, Ecology.

[32]  Hugo Asselin,et al.  Structural and Spatial Characteristics of Old-Growth Temperate Deciduous Forests at Their Northern Distribution Limit , 2014 .

[33]  S. Bédard,et al.  Growth following single-tree selection cutting in Québec northern hardwoods , 2003 .

[34]  S. Hubbell,et al.  Crown Asymmetry, Treefalls, and Repeat Disturbance of Broad‐Leaved Forest Gaps , 1991 .

[35]  M. Lechowicz,et al.  Changes in understory light regime in a beech maple forest after a severe ice storm , 2007 .

[36]  P. White,et al.  The Ecology of Natural Disturbance and Patch Dynamics , 1986 .

[37]  Judith Bayard Cushing,et al.  A framework to categorize forest structure concepts , 2008 .

[38]  B. Beckage,et al.  SEEDLING SURVIVAL AND GROWTH OF THREE FOREST TREE SPECIES: THE ROLE OF SPATIAL HETEROGENEITY , 2003 .

[39]  James R. Runkle,et al.  Treefalls Revisited: Gap Dynamics in the Southern Appalachians , 1987 .

[40]  C. Messier,et al.  Avoiding ecosystem collapse in managed forest ecosystems , 2016 .

[41]  A. D’Amato,et al.  Regeneration responses to gap size and coarse woody debris within natural disturbance-based silvicultural systems in northeastern Minnesota, USA , 2011 .

[42]  D. Houston.  Major New Tree Disease Epidemics: Beech Bark Disease , 1994 .

[43]  Hugo Asselin,et al.  Gap dynamics of late successional sugar maple–yellow birch forests at their northern range limit , 2017 .

[44]  T. Kuuluvainen.  Forest Management and Biodiversity Conservation Based on Natural Ecosystem Dynamics in Northern Europe: The Complexity Challenge , 2009, Ambio.

[45]  Marilou Beaudet,et al.  Effect of a major ice storm on understory light conditions in an old-growth Acer–Fagus forest: Pattern of recovery over seven years , 2007 .

[46]  S. Carpenter,et al.  Early warnings of unknown nonlinear shifts: a nonparametric approach. , 2011, Ecology.

[47]  Robert S. Seymour,et al.  Natural disturbance regimes in northeastern North America—evaluating silvicultural systems using natural scales and frequencies , 2002 .

[48]  F. H. Bormann,et al.  Catastrophic disturbance and the steady state in northern hardwood forests , 1979 .