Bumping the table!

1. Bumping the table! global local SPACE Evolving and mobile pieces (life-forms) Time: past future Why are the pieces laid out as they are, and how are their distributions changing? Changing table-top (environment)

2. Disturbanceandsuccession Forms of disturbance Spatio-temporal-severity variation in disturbance regimes Primary & secondary succession Documenting successional change Autogenic and allogenic processes Forest dynamics Change as a stochastic processes Climax?

3. Abiotice.g. fire wind landslides avalanches volcanic eruptions flooding glaciation bolide impacts Biotice.g. tree-fall herbivore damage pathogens Anthropogenice.g. logging urbanization pollution fire Forms of disturbance

4. Spatio-temporal-severity variation in disturbance regimes How often is the community impacted (=can populations reproduce?) How severe is the damage (=do populations recover?)How big are the disturbed patches (=how long to recolonize)? Interval Severity Size

5. Disturbances: spatio- temporal variation Cox CB, Moore PD. 2000. Biogeography: an ecological and evolutionary approach. Blackwell Science, 298 pp.

6. Small-scale disturbances:right: treefall in redwoods (CA);below: lightning kill in mangroves (FLA) images: http://www.thomasbdunklin.com/albums/HumboldtRedwoods; http://sofia.usgs.gov/publications/fs/2004-3016

7. Wind • e.g. Coastal forest, BC, December 2006. • In Stanley Park some 10% of the trees were blown down or severely damaged by winds gusting >100 km/hr.

8. AvalancheSubalpine forest restricted to slopes that are stable and not prone to snow slides or avalanches(Cascade Highway, WA)

9. Fire • severe fires remove forest canopy • > increase light level on forest floor • fires mineralize organic layers on forest floor > increase nutrient availability • many tree species fire tolerant

10. Adaptations to fire: forest trees • thick bark (e.g. ponderosa pine) • regrowth from epicormic shoots (e.g. eucalypts; new leaves 2 weeks after fire) • stimulation of seed dispersal in serotinous species (e.g. jack pine)

11. Fire intervals • Fire scars indicate thermal damage to the cambial layer; rings indicate age of event Images: http:// www.ltrr.arizona.edu/ sngc/studies/pftrd.htm

12. After the disturbance: succession • “Species - by - species replacement process in an ecological community through time”. • Focus: short-term temporal change in a community as it develops or recovers from disturbance. • Modern ideas about succession derive from Gleason’s (1920’s) individualistic species behaviour concept and Horn’s (1970’s) notions of replacement as a stochastic process.

13. Primary and secondary succession • Primary - development from an initial condition or after a disturbance that sterilized the local landscape (i.e. colonization of a barren substrate). • Secondary - recovery from a disturbance that did not extinguish all life forms in the local area.

14. Primary successions on “sterile” coastal substrates mudflat beach gravel dune sand

15. Primary succession on “sterile” rocky substrates lava flow debris flow

16. Primary succession:where do the colonizers come from?What controls their success? Mt. St Helens, 1981

17. Secondary succession: disturbance does not clean the slate complete burn partial burn partial clearance

18. Documenting succession • DIRECT OBSERVATION:useful for situations where species turnover is rapid • SPATIAL ANALOGUE:most-commonly employed - requires mosaic of communities of different ages • TEMPORAL RECONSTRUCTION:possible only in depositional environments

19. Ways of studying succession: the example of the River Fal (UK) estuarine-floodplain woodland marsh core site

20. Spatial analogue: a transect from marsh through woodland communities replacement series?

21. Temporal re-construction: a core from floodplain of River Fal(core site on previous slide)

22. Successional process Degenerative: e.g. scavengers on carrion (Gail Anderson); bacteria, fungi, etc. skeletonizing a leaf, ….. Allogenic: community changes driven by external forces (=exogenous) such as sedimentation on a floodplain. Autogenic: community changes driven by internal forces (=endogenous) such as shading of forest floor by tree canopy

23. Allogenic succession: e.g. progradation and aggradation of a river delta 10 ka 5 ka (~AD 1850-80) now

24. Allogenic succession: e.g. Fraser River delta Primary driving factor - sedimentation, which is linked to channel position and tidal currents. The channel banks are better-drained than the areas between the distributaries.

25. Relay dynamics • Mature, even-aged stand of pioneer trees with understorey of shade-tolerant species; • Pioneers die, replaced gradually by shade-tolerant trees; • Mixed canopy with replacement by shade-tolerant trees graphic: www.na.fs.fed.us/spfo/ pubs/misc/ecoforest/dyn.htm

26. Canopy-gap dynamics • Mature, mixed-age stand with canopy and understorey of shade-tolerant trees; • Canopy trees die (by senility or windthrow), competition in gaps • Replacement by trees that grow most quickly in gap environment graphic: www.na.fs.fed.us/spfo/ pubs/misc/ecoforest/dyn.htm

27. Autogenic succession on deglaciated terrain, Glacier Bay foreland, AK.

28. Glacier Bay successional stages

29. Glacier Bay community dynamics Sadava, D. et al. (2004) Life: The Science of Biology, Sinauer Associates and W. H. Freeman.

30. Seed sources and succession Deglaciated in 1968, this surface supported a continuous carpet of Dryas plus scattered willow and cottonwood saplings in 2005. Alder and spruce seed sources are too distant to allow rapid colonization of this site,but in areas closer to seed sources colonization by these species can be rapid. Source: Milner et al., 2007, Bioscience, 57, 237-247

31. Concomitant environmental changes [acidification, paludification] http://arnica.csustan.edu/boty1050/Ecology/glacier_bay.htm

32. Autogenic succession: natural reforestation of abandoned fields in the southeastern U.S.A. (Georgia, Carolinas) RELAY GAP

33. Abandoned field succession - birds

34. Forest succession: regeneration niches Sun Deep shade pioneer trees regeneration niche weeds time-trajectory Light level climax forest trees Thin Thick Organic matter depth

35. Forest succession patterns slower, less complex

36. Succession: a stochastic process Basic concept: forest succession is a lottery that can be modelled by a Markov chain process (which assigns probabilities to competing outcomes in a sequence). Ideas primarily developed by Henry Horn in 1970’s based on his observations in the Princeton Research Forest (a mixed hardwood forest) in northeastern U.S.A.

37. Markov chain analysis of forest succession: a lottery to replace canopy dominants in gaps STEP 1: map forest structure focussing on species of canopy dominants (X) and saplings (x): F transect in plot A a H f h h h h h h h h h a h If this alder dies, what will replace it?

38. Markov chain analysis STEP 2: Tabulate replacement matrix for all transects # saplings (replacements) Canopy # alder fir hemlock sum Alder 132 4 14 20Fir 51 1 8 10 Hemlock 20 0 1414 (based on hypothetical example from SFU woods)

39. saplings (replacements) Canopy alder fir hemlock Alder 0.1 0.2 0.7Fir 0.1 0.1 0.8 Hemlock 0.0 0.0 1.0 Markov chain analysis STEP 3: Calculate transitional probabilities: e.g. for a dying alder 2/20 potential replacements are alders = 0.1 probaility of an alder x alder replacement.

40. Markov chain analysis STEP 4: represent as a Markov chain, showing transitional probabilities 0.1 0.1 1.0 0.2 0.8 Alder Fir Hemlock 0.1 0.7

41. Predicting future forest structure from Markov model STEP 5: Multiply canopy structure by transition matrix For alder: each of the 13 canopy alders will likely be replaced by 0.1 alder saplings = 1.3 alders; each of the 5 fir canopy trees will likely be replaced by 0.1 alder saplings = 0.5 alders; and each of the 2 hemlock canopy trees will likely be replaced by (2 x 0.0 alder saplings) = 0.0 alders. Alder abundance in the plot in the next generation is therefore = 1.3 + 0.5 + 0 = 1.8 alders

42. Multi-generation forecasting STEP 6: Repeat step 5 ad nauseam Generation Canopy 1 2 3 4Alder 13 1.8 0.5 etc.Fir 5 3.1 0.7 etc. Hemlock 2 15.1 18.8 etc.

43. Comparing successional pathways and outcomes Horn suggested that successional transition matrices can be grouped into three types illustrating: A B A. Chronic, patchy disturbance: C D B. Obligatory succession: A B C D C. Competitive hierarchy: A B C D

44. Is there a predictable endpoint? Is there a singular “climax” forest?Horn’s “quasi-reality” from the Princeton forest plot blackgum gray birch beech red maple Quasi-stable monoclimax: forest of beech + others

45. Are polyclimaxes possible? Jerry Olson’s study of the Lake Michigan dunes

46. Lake Michigan dunes: polyclimax succession?

47. Landscape-scale analysis of the successional mosaic Boreal forest, Canada Simpson Desert, Australia Date of wildfire 50 km ~5km http://www.gsfc.nasa.gov/topstory/2003/0311firecarbon.html http://earthobservatory.nasa.gov/

48. Disturbance and invasive species Chinese tallow tree The tallow tree (Sapium sebiferum L.), a native of China introduced into the US by Benjamin Franklin in 1776, is rapidly invading the disturbed areas. Its seeds, which can remain viable in the soil for >100 years, are spread by birds, and it grows rapidly to 10 m tall. 13.6 M m3 of timber (mainly in Louisiana) damaged by Hurricane Katrina in September, 2005