Riparian Development Hypothesis

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Helfield, J. M. , and R. J Naiman . 2001. Effects of Salmon-Derived Nitrogen on Riparian Forest Growth and Implications for Stream Productivity. Ecology 82: 2403-2409. What was the main point of the article that you chose? This study aims to explore how terrestrial ecosystems are linked to aquatic ecosystems, particularly through resources. This is examined by observing how MDN affects riparian growth. Briefly explain or describe the scientific method presented in the article. a. What was the hypothesis? Marine derived nitrogen (MDN) has an effect on riparian vegetation. b. What were the predictions? Areas with a high level of MDN such as salmon reproductive areas, will have more enhanced riparian growth than a non-reproductive …show more content…

The independent variable is the levels of MDN. b. What kind of study was it? Observational? Experimental? Modelling? This is an observational study as no treatments were placed on the study sites, instead samples were taken from sites of interest and analyzed. c. What statistics were used? Three major descriptive statistics calculations were done. Firstly, the basal area increment (BAI) was found for tree growth, the ratio of N15 to N14, 15N was calculated, and the %MDN of the samples was found. d. What assumptions were made? This study assumes that nitrogen is the limiting factor to riparian growth. Another is that MDN is the most significant contributor to nitrogen levels in the study site. What was the primary finding(s) of this article? Helfield and Naiman’s results showed that foliar N levels and 15N were significantly higher at spawning sites compared to the reference sites. They suggest that their hypothesis is supported and MDN provides nutrition to riparian vegetation. a. Was anything particularly noteworthy? Helfield and Naiman propose that there could be a positive feedback loop in which MDN helps riparian vegetation growth and in return the stream receives LWD (large woody

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