1. LTER Core Dataset Annual Seed Rain Current Lead: Jill Johnstone with contributions from Janet Pritchard, Joy Clein, and Brian Charlton

2. 2008 BNZ LTER Symposium2 Data Scope & Availability 1957-1982: Early measurements –UP1A (white spruce); lots of issues –Burned in 1983 1983-1989: Additional sites added BNZ Sites: 5 Floodplain + 3 Upland –approx. 20 year record 2004: New site added at CPCRW Data available up to 2007 on website (but hard to find – poor keyword control) Some missing data – even in recent years

3. 2008 BNZ LTER Symposium3 Methods Seeds collected in lined litter traps (n=1-6) –Trap size now standardized to 50x50 cm –Collected in spring or early summer All tree/shrub seeds sorted by species & counted –Pool related species within a genus (i.e. Alnus, Picea) Germination trials for viability Averaged traps annually to provide –Total seeds/species/m 2 –Viable seeds/species/m 2 Species: Alnus incana, Alnus viridis, Betula neoalaskana, Picea glauca, Picea mariana, Larix laricina

4. 2008 BNZ LTER Symposium4 A look at the data Viable seeds per trap: Note log scale! Lots of variability within and between years

5. 2008 BNZ LTER Symposium5 Upland Sites Seed production tends to be synchronous between deciduous species Seed production tends to be synchronous between sites

6. 2008 BNZ LTER Symposium6 Upland Sites White spruce mast years (’70,’72,’77,’82,’98,’00) Synchronous between UP1a/3a; Very low production in UP2a

7. 2008 BNZ LTER Symposium7 Floodplain Sites General pattern of synchronous peaks in deciduous seed production Black Spruce White spruce mast years (’87,’90,’97/98,’00,’02) Black spruce (FP5a) shows more constant seed production, but peaks are synchronous with white spruce

8. 2008 BNZ LTER Symposium8 Current Assessment Seed trap data are suitable for evaluating: –Temporal synchronicity in seed production between species and sites –Relation between seed production and climate Do we have a priori hypotheses? These data are not suitable to evaluate: –Changes in seed production over succession Lack of replication among succession stages However, can relate seed production to basal area –Changes in seed production over time Time series too short relative to large annual variability Possible exception with earliest succession stages

9. 2008 BNZ LTER Symposium9 Recommendations Seed trap data are very time-consuming to collect Need a strong rationale for continued sampling High within-site variability –Should not reduce trap samples Poor ability to detect successional effects –Remove sampling from low-interest sites Possible sites to keep: –Early succession stages to identify initiation of reproductive maturity? UP1a – white spruce FP1a – alder (documented) FP2a – white spruce –Maintain longest datasets? UP3a has best quality, long term data for WS (1970- current) –Maintain “representative” mature stand within UP & FP? UP3a + [FP3a or FP4a]

10. 2008 BNZ LTER Symposium10 Recommendations Reduce BNZ sites: –FP: 5 => 2 –UP: 3 => 2 CPCRW: –Continue Helmer’s Ridge? –Add 2004 burned sites already established BS seed only Stop in 2014 Reduce sampling time –Single species samples? CPCRW: Black spruce only –Automate seed counting seed weight => number? digital counting Continue germination trials –Critical info on viability

11. 2008 BNZ LTER Symposium11 Shift in research design Suggest a focus on three themes: Synchrony –Analysis with current dataset –Synchronous patterns between sites and species, and relation to possible climate triggers Annual variation and trends –Maintain long-term data for select sites –Focus on temporal variation in relation to climate change Succession mechanisms –Assess seed availability in early succession sites –Key mechanism for predicting species recruitment Need a clear justification for continued sampling