Species Richness and Clear Cut Age Brooke Gauthier Charlie Karoff Tyler Quinn Smith Peter Tansey All

Introduction Clear cutting has noticeable effects on species composition and succession of forests. Physiological characteristics (Elliott et al. 1996) Richness per 100 individuals increased with successional stage (Bruelheide et al. 2011) Species diversity over successional time in abandoned fields (Howard and Lee 2003): Increase? Decrease? Peak sometime? No trend? Charlie Clear cutting impacts forest succession: the sequential changes in abundances of dominant species in a community.  -Often due to physiological characteristics of trees such as stress tolerance, rapid growth, or high nutrient acquisition (Elliott et al.) Bruelheide..... Howard and Lee tested four hypotheses of how species diversity would change over successional time: increase, decrease, peak at mid-succession, or show no trend?

Objective Understand the relationship between clear cut age and species richness. Hypothesis: tree species richness will increase with the age of clear cut. Peter or Tyler

Methods Field Lab Analyzed data in Microsoft Excel UNH Woodman Horticultural Farm in Durham, NH 9 plots total in 3 different clear cuts (1985, 1989, and 2011) Plots 30 meters apart Identified 20 trees closest to midpoint  Analyzed data in Microsoft Excel Split trees into groups (intolerant, lower mid-tolerant, high mid-tolerant and tolerant) Used JMP Pro 13 to run Kruskal-Wallis test Brooke

Brooke

Results Tyler

Tyler

Tyler

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Peter

Results Continued Peter

Statistical Analysis Species richness increased significantly with clear cut age.  Kruskal-Wallis Test  X^2 > 5.954 d.f. = 2  P < 0.05 Brooke

Discussion Tree species richness did increase with age of clear cut. Richness was lowest year after clear cut and increased thereafter (Grove et al. 1992) Intermediate Succession Hypothesis? (Howard and Lee 2003) Tyler

Discussion Data shows patterns of species composition relating to shade tolerance. Elliott et al. (1996) found clear cutting to favor shade-intolerant species initially and shade-tolerant species 10-15 years after.    Peter Lienard et al. 2015

Limitations Time restrictions Inexperience in tree species identification Physiography varied among clear cuts Brooke www.hfpi.ca

Conclusion Maximum species diversity in immediate years following the clear cut. Self-thinning and interspecific competition lead to decreased richness. Shade tolerance of species within the stand that have a lower R* will prevail better than tree species with a higher R*. When will these stands experience a plateau or decrease in richness? Charlie

Literature Cited  Bruelheide, H., Bööhnke, M., Both, S., Fang, T., Assmann, T., Baruffol, M. et al. (2011). Community assembly during secondary forest succession in a Chinese subtropical forest. Ecological Monographs, 81, 25-41. Elliott, K., Boring, L., Swank, W., and B. Haines. 1996. Successional changes in plant species diversity and composition after clearcutting a Southern Appalacian watershed. Forest Ecology and Management. 92(1997): 67-85. Grove, J., Wayne Martin, C., Paul, G., Solomon, D., and J. Hornbeck. 1992. Plant species diversity on even-aged harvests at the Hubbard Brook. Experimental Forest: 10-year results. Canadian Journal of Forest Research. 22(11): 1800-1806. Howard, L. and T. D. Lee. 2003. Temporal patterns of vascular plant diversity in southeastern New Hampshire forests. Forest Ecology and Management. 185(1-2): 5-20. Lienard, J., Florescu, I. & N. Strigul. 2015. An appraisal of the classic forest succession paradigm with the shade tolerance index. PloS one, 10, e0117138.