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Dissertation
Ecological factors influencing spatial patterns in Sphagnum flavicomans and Sphagnum pulchrum from the New Jersey Pine Barrens
Doctor of Philosophy (Ph.D.), Drexel University
Oct 1999
DOI:
https://doi.org/10.17918/00000478
Abstract
Sphagnum flavicomans (Card.) Warnst. and Sphagnum pulchrum (Braithw.) Warnst. commonly grow along hummock-hollow gradients in the nutrient poor minerotrophic fens (= cedar bogs) of the New Jersey Pine Barrens. It is poorly understood how these co-occuring species become spatially partitioned into ordered niche space with S. flavicomans positioned above and at a greater height above the water-table (HAW) than S. pulchrum. The vertical distribution of S. flavicomans (ca. 5-30 cm HAW) and S. pulchrum (ca. 0-8 cm HAW) narrowly overlaps in a zone of coexistence (ZOC [special characters omitted] 5-8 cm. HAW) where digital image analysis detected shifts in species dominance (viz. cover and capitula density per unit area) concomitant with seasonal variation in water-table. Sphagnum flavicomans increased niche space during periods of lowered water table (i.e. drought); whereas, S. pulchrum increased niche space during periods of elevated water-table. Shifts in dominance were attributed to either overgrowth competition or ability to maintain a positive water balance. In natural position, S. pulchrum had a greater linear growth rate than S. flavicomans, 2.72 and 2.05 x 10 -2 (dm2 d-1); however, when S. flavicomans was transplanted into the S. pulchrum zone, it had an extremely high linear growth rate of 3.20 x 10 -2 (dm2 d-1) but, paradoxically, was overgrown by slower growing S. pulchrum. The post-interactive niche of S. flavicomans did not include the hollow and the associated survival asymmetry was attributed to differences in growth habit rather than differential growth rate. Niche partitioning in the upper hummock was more influenced by physiological factors. There were no interspecific differences in ability to resist desiccation or to photosynthesize at a lower water content. However, S. flavicomans had a greater capillarity and positive water balance at a greater HAW such that it had a higher rate of photosynthesis and associated linear growth than S. pulchrum. The fundamental niche of S. flavicomans includes hummock tops; whereas, the fundamental niche of S. pulchrum is restricted to a position closer to the water-table.
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Details
- Title
- Ecological factors influencing spatial patterns in Sphagnum flavicomans and Sphagnum pulchrum from the New Jersey Pine Barrens
- Creators
- Walter F. Bien
- Contributors
- Susan Soltau Kilham (Advisor)James Robert Spotila (Advisor)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- xxiii, 199 pages
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- Bioscience and Biotechnology [Historical]; College of Arts and Sciences; Drexel University
- Other Identifier
- 991014970196904721