. The ecology of delta marshes of coastal Louisiana : a community profile . J MICROBIAL ^ ANAEROBIC "nIO" METABOLISM J 'â "flONS Figure 48. Marsh soil transformations that result from tidal flooding. inland, but for shorter periods of time (Table 7), and the inland floodwaters are more slowly exchanged. Furthermore, the streamside marshes drain better on falling tides because their sediments are coarser. They also contain more reducible mineral ions to buffer redox changes. All these factors lead to stronger reducing potentials in inland marshes than streamside. The strongly pot
. The ecology of delta marshes of coastal Louisiana : a community profile . J MICROBIAL ^ ANAEROBIC "nIO" METABOLISM J 'â "flONS Figure 48. Marsh soil transformations that result from tidal flooding. inland, but for shorter periods of time (Table 7), and the inland floodwaters are more slowly exchanged. Furthermore, the streamside marshes drain better on falling tides because their sediments are coarser. They also contain more reducible mineral ions to buffer redox changes. All these factors lead to stronger reducing potentials in inland marshes than streamside. The strongly potential. nutrient, available chemistry of many minerals is influenced by the redox Phosphorus, a key plant is much more soluble (and hence to plants) under reduced than oxidized conditions (Delaune et al. 1981). Inorganic nitrogen, the primary limiting nutrient in marshes, is reduced to the aimonium ion which is readily absorbed by plant roots. More nutrients are delivered to streamside than to inland sites; this should favor streamside plant growth rates. Organic nitrogen is also more rapidly mineralized to ammonium in streamside sites (Brannon 1973). Other minerals may be transformed to toxins or accumulate in toxic concentra- tions (for example,sulfide) (Hollis 1967). Toxic byproducts of anaerobic microbial metabolism may accumulate. In general, the levels of these potential toxins are higher in inland marshes than streamside marshes, increasing the stress on inland plants. Finally, referring again to Figure 48, the direct flushing of marsh soils and the leaching of olant leaves can dilute toxic materials, reducing their activity. Flushing occurs more readily in streamside sites, reducing the potential for accumulation of toxins. With all these potential effects it is not surpris- ing that plant production is higher along streams than inland. Soil analyses can, at times, mislead. For example, it has been found that ammonium in marsh soil interstitial water is more concentrat
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