Boreal Moss Communities: Succession and Implications for Establishment After Fire in Alberta's Spruce-Dominated Forests

Boreal moss communities: succession and implications for establishment after fire in Alberta’s spruce-dominated forests

Michael Simpson Department of Biological Sciences, University of Alberta Supervisor: Dr Mark Dale Funaria hygrometrica Hylocomium splendens

Ceratodon purpureus

Ptilium crista- castrensis

Bryum argenteum

Pleurozium schreberi Polytrichum juniperinum RESEARCH OBJECTIVES

1. Successional change in boreal moss communities – characteristics and controls A. Describe short-term variations in composition, diversity and species distribution in early- successional communities B. Test hypotheses about controls on timing of establishment of late-successional feather mosses C. Generate a model of species change over time

2. Implications for wider forest community • Effects of moss on post-fire recruitment of selected conifer species HYPOTHESES

Establishment and growth of feather mosses is controlled by: • Available substrates – Early successional: mineral-based; high pH, low nutrients, dry c.f. Late successional: high OM, low pH, high nutrients, moist • Limited tolerance for low humidity, increased water loss – High exposure in early successional (open) stands • Reproduction primarily asexual (vegetative propagation); delays dispersal of propagules • Interactions between substrate, stand age, reproductive strategy HYPOTHESIS 1: Establishment and growth of feather mosses is controlled by available substrates

1. Compare the Pleurozium schreberi establishment potential and growth of fragments of 2 feather mosses on burned and unburned substrates

Ptilium crista-castrensis Ash Burned moss

Burned mineral soil Humus 2 FRAGMENT SIZES

Small: unbranched, mean lengths: Ptilium Large: branching, 5.6 mm Pleurozium 8.2 ~ 4 cm long, cut mm, dislodged using a with scissors soil sieve • 2.5” square plastic pots – 24 or 36 = 1 ‘block’ • 5 blocks per stand in: – SMALL frags: 3 early- & 1 late-successional stand – LARGE frags: 1 late- successional stand • Sunk into humus on forest floor • Fragments tied to paper clips • SMALL - 12 months LARGE - 3 months ) ) ) 5.0 ta ta ta SMALL: Total length of a 4.5 a s. da s. da fragments with living shoots s. da a an an an h) h) h) tr tr tr t t t 4.0 o o o engt engt – Only 2 Pleurozium fragments on engt l l l ( ( ( T T T -ro -ro -ro R R ash and 2 Ptilium fragments total R re re re Q Q Q 3.5 S S with growth S E E E 1 S 1 S 1 S b (squa (squa (squa - - – Fragments on all substrates - 3.0 th th th ng ng ng ean + ean + significantly longer than initial ean + 2.5 M M M le le le

length (P<0.05) N = 18 10 22 12 Bu CO M Hu tal tal tal in rn NT e mu e ra d RO l s s to to to m o L o s il s t t t 10 en en en Mean Mean Mean SUBTYPE Substrate 8 327 agm agm agm fr fr fr r r r e e e p p p 6 ts ts ts oo oo oo 4 399 sh sh sh f f f S S S r o r o r o 2 OT OT OT be be be O O O # shoots per fragment H H H 0 #S #S #S num num num N = 20 22 13 – Few shoots; no difference n n n Bu Mi Hu n r e m ne r u d m a s between substrates l s o o s il s Media Media Media

SubstratSubstratee 8.0 7 Ptilium Ptilium a s ta)ta) a a 6 162

AA a dada

7.5 hoot 5 dd de s i

meme 168 s 4 ean LMean LM rr 7.0 a ts m m der bcd b sfosfo 3 or of of oo - nn t

s c ootoot r

6.5 i

sh 2 f tra tra e re r tt b e of oo

oo 1 185 quarquar sid 6.0 ber SS m e-re-r d

u 0 3117 der N arar

or -1 ququ 5.5 ss N = 9 10 15 7 11 N = 9 10 15 7 11 ((

)) As B C M H A B CO M H u ON i um sh u iner u h r ner first- rned m N mu 7.4 ned m T us f 4.6 T R al R a s Pleurozium O so Pleurozium OL l s o L o o a

r o i s il s s l 7.2 s a 4.4 s be is (mmis (mm

AA ab 7.0 hoot ab c s axax Substrate 4.2 bc Substrate LM LM de i in in num s aa 6.8 eanean

n 4.0 ab r e m m

ab d 6.6 of of 3.8 or tt of mof m -

t oo s oo Media r thth 6.4 b 3.6 40 fi e re r ngng

b of 169 uaruar 6.2 3.4 er le le qq b SS m

6.0 u 3.2 N

MeanMean 5.8 3.0 N = 8 10 15 11 9 N = 8 10 15 11 9 A Bu C M H As Bu CO M Hu sh O in um i rn NT er h r NT ner m ed m us ned u RO al RO al s so so L mo o il L s s il s s Substrate SubstratSubstrate e Substrate HYPOTHESIS 2: Establishment and growth of feather mosses is controlled by limited tolerance for exposure (low humidity, increased water loss)

1. Compare the establishment potential and growth of fragments of 2 species sown in recently burned (open) stands 2. Test for differences between 3 fragment sizes • LARGE, SMALL, MULCH • Soil surface excavated to ~ 2.5 cm and replaced with humus • 5 blocks in 5 stands – 4 recently burned (open) – 1 late-successional • 4 x 4 blocks marked out using plastic frame • Fragments pinned/spread within squares • Number of fragments with living shoots recorded after 12 months Number of Pleurozium46 fragmNumbeer ofnts frag rmeecovnts reecroevedre afted r 12 months 45 Number of Pleurozium fragments recovered, and number of fragments found with shoots Number of fragments with shoots 40 and number40 of recovacroses raell sdta ndsfragm (Augusetnts 2004) with living shoots 39 5040 50 35 Living shoots (all stands) 4646 Number of fragments recovered

45s 35 45 Number of fragments with shoots 30 nt e 43 40m 30 43 3838 40 g

• Growth found in few a 25 r 35 f 25 35 of r nts 20 e MULCH replicates e

m 3020 30 g mb

a 15 r Nu f 2515 25

• Few SMALL fragments of 10 er 2010 20 mb had living shoots u 5 N 15 5 15 0 15151 0 0 10 10 • Almost all LARGE BRANCHES MULCH SHOOT TIPS 44 5 Fragment size 5 fragments had living 4 0 0 shoots NumBRbeANCr ofH PEtiSlium fragments recovMerUeLd,CH and number of fragmeSHntsO foOTu nTdIP wSith shootsFra g(Amugenut ssti ze2004) 50 45 46 Number of fragments recovered NumbeNumrb ofer of Pt Ptiliumilium frafragmentsgments recover erd,e covand numbeeredr ofaft fragerm 1en2t smonths found with and 45 Number of fragments with shoots 40 number 40of recoversehood tsfragm (Auguset nts2004 )with living shoots 5040 39 45 35 4646 Number of fragments recovered

45s 35 40 Number of fragments with shoots 30 nt 40 e 40 3939

40m 30 35 g

a 25 r f s 35

t 25 30 n of r

e 20 e m 3020 mb

ag 25 r 15 f Nu f 2515 20

er o 10 b 2010 m 15 Nu 15 5 5 1 0 10 Number of fragments recovered 10 0 0 BRANCHES MULCH SHOOT TIPS 5 5 Fragment size 1 Number of fragments with shoots 00 1 0 0 BRANCHES MULCH SHOOT TIPS Fragment size OBJECTIVE 1: PRELIMINARY CONCLUSIONS

• Establishment and growth on burned/mineral substrates and in open stands possible Therefore… • Timing of establishment of feather mosses primarily a function of dispersal limitation, but… • Exposure and substrate influence timing thorough interactions with fragment size – Larger fragments likely to be more successful, but… – Fewer of them – Long distance saltation dispersal = long process (which may be accompanied by loss of viability) – Other vectors may be quicker – rare event? OBJECTIVE 1 – PRELIMINARY CONCLUSIONS

• Suggests establishment by fragments is increasingly rare at greater distances from fire boundary – Spread from boundaries of fire and residuals limited – In the middle of large burns, post-fire recolonisation likely to be slow • Do distant colonies establish from fragments? – may occur primarily through spores • Recolonisation likely to be faster post-logging – source of propagules in situ – would compress intermediate successional stages and constrain opportunities of species associated with them RESEARCH OBJECTIVES

1. Successional dynamics in boreal moss communities A. Describe short-term variations in composition, diversity and species distribution in early- successional communities B. Test hypotheses about controls on timing of establishment of late-successional feather mosses C. Generate a model of species change over time

2. Implications for wider forest community • Effects of moss on post-fire recruitment of selected conifer species RESEARCH OBJECTIVES

RESEARCH OBJECTIVES

Post-fire recruitment is influenced by early successional conditions • Burned feather moss remains = ‘biological legacy’ • ‘persisting living and dead structures’ left by disturbances (Franklin et al. 2002) • Dry; elevate seeds and seedlings • Previous studies indicate living moss carpets can enhance seed germination and seedling survival • Moist; cover; moss-cyanobacteria associations might enhance seedling growth compared with open soil – N fixation • Potential influence on understory and canopy spatial structure and composition Assess the impact of: – BURNED MOSS – LIVING CARPETS OF EARLY SUCCESSIONAL MOSS …on seed germination, and short-term survival and growth of seedlings of selected boreal tree species BURNED MOSS - METHODS (SEEDLINGS)

• Seeds of Picea glauca and Larix laricina pre-germinated on moist filter paper in Petri plates. • 10 germinants per species planted in 20 4-inch pots of burned moss, mineral soil or humus subsoil • Pots in a growth chamber, watered every 3 days. • Survival recorded periodically; mean dry weight and height after 97 days Surviving P. glauca and L. laricina seedlings 23-28 days after Surviving Picea glauca and Larix laricina seedlings 23-28 days after sowing,so wainsg a, as proportion a proportion off s seedeeds ssow son (wN=n1 5(N0) =150) 1.00 SEEDLING SURVIVAL Picea glauca 0.90 0.930.93 Larix laricina

0.80 Between 28 and 97 days 0.790.79 0.780.78 0.77 0.70 0.77

n 0.70 after sowing: w 0.70 0.60 s so ed e s • For both species, survival f 0.50 o

n 0.510.51 o i t r declined most on burned o 0.40 Prop moss 0.30 – L. laricina 51% to 20% 0.20 0.10 – P. glauca 70% to 53% 0.00 BURNED MINERAL SOIL SUB-SOIL BURNED MOSS Substrate

Surviving P. glauca and L. laricina seedlings 92-97 days after At 97 days: Surviving Picea glauca and Larix laricina seedlings 92-97 days after sowing,sow ainsg a, as proportion a proportion oof fs eseededs ssow son (Nw=n15 (N0) =150) • L. laricina survival lowest on 1.00 Picea glauca burned moss, highest on 0.90 Larix laricina humus 0.80 0.70 0.730.73 n 0.71

w 0.71

• P. glauca survival lowest on so 0.60 0.64 s 0.64 seed burned moss, highest on f 0.50 o 0.530.53 n o

i 0.48 t 0.49 r

o 0.40 p

mineral soil o r P 0.30

0.20 0.200.20 0.10

0.00 BURNED MINERAL SOIL SUB-SOIL BURNED MOSS Substrate -2.0 Picea glauca SEEDLING GROWTH a

-2.1 Mean dry weight • Both species: burned moss ab ta) a d significantly different from b -2.2 ) t

humus but not mineral soil med g(W o l I (P<0.01) sfor C an %

tr -2.3 95 N = 124 138 126 Burned moss Mineral soil Humus

) (log -1.8

(g TreaLaritmentx laricina a Mean height -1.9 ight e w • P. glauca - no significant -2.0

difference between substrates dry • L. laricina: burned moss -2.1

Mean -2.2 b significantly different from b ) humus but not mineral soil t -2.3 W ( g

(P<0.01) o l I -2.4 C % -2.5 95 N = 42 98 148 Burned moss Mineral soil Humus

Treatment Substrate PRELIMINARY CONCLUSIONS

• Burned feather mosses are a poor substrate for survival of seedlings, esp. of L. laricina. – Conditions more amenable in growth chamber? – NO SEEDLINGS on burned moss in field trial! • Optimum growth of successful germinants will not occur on burned moss • L. laricina likely to form minor component of canopy in stands where burned moss had high cover LIVE MOSS - METHODS

• Pilot study in field – low germination • Seeds of P. glauca, L. laricina and P. mariana (black spruce) sown in trays on 3 treatments: – Moss present – Moss cleared – Open soil

• Controls sown on filter paper and Jiffy Pots© • Germination and survival data collected weekly (ongoing) Survival of L. laricina seedlings up to 84 days after sowing as a Survival of Larix laricina seedlings as a proportion of seeds sown proportion of seeds sown Germination – All species 1

• Very high on all treatments 0.9 • Little difference between 0.8 treatments 0.7 0.6 n tio r

o 0.5 p o Pr 0.4

Seedling survival 0.3 Moss removed • Little difference between 0.2 Moss present Open soil 0.1 treatments for P. glauca Control 2 (JP) 0 7 1421283542495663707784 • L. laricina – germination Time since sowing (days) highest but survival lowest Survival of P. mariana seedlings up to 84 days after sowing as a Survival of Picea mariana seedlings as a proportion of seeds sown proportion of seeds sown on Open soil 1

• P. mariana – germination 0.9 highest but survival lowest 0.8 on Moss present 0.7 0.6 n tio 0.5 por o r P 0.4

0.3 Moss removed 0.2 Moss present

0.1 Open soil Control 2 (JP) 0 7 1421283542495663707784 Time since sowing (days) PRELIMINARY CONCLUSIONS

• Little difference between treatments – No effect on germination and survival? – Differences moderated in growth chamber? • Effects on growth to be determined… • Mortality of L. laricina seedlings might be lower in presence of early successional moss carpets? • Mortality of P. mariana seedlings might be greater in moss patches? ACKNOWLEDGEMENTS

• Dr. Mark Dale, Dr. J. F. Cahill, Dr. Dennis Gignac • Chisholm-Dogrib Fire Research Initiative (Foothills Model Forest, Alberta), Alberta Conservation Association Grants for Biodiversity Research • Alberta Sustainable Resource Development (Alberta Tree Improvement & Seed Centre) • Devonian Botanic Garden • Steve Morse, Lindsay Elliot, Alexandra Rutherford, Chris Drake, Jess Leatherdale, Rose Muto