Print PageA moss-dominated seepage wetland growing on a vertical rock face in southeastern Pennsylvania was studied over an annual cycle in 2010-2011. The ecosystem was sampled four times during different seasons through the annual cycle. On each sample date, quadrat samples of vegetation were collected, sorted by moss species and weighed for water content and biomass. Macroinvertebrate taxa were separated from the moss and the soil, and counted and identified. Water flow was measured by collecting a known volume of water over time from locations where seepage water dripped off the moss cover.
Results/Conclusions
The system was dominated by Hedwigia sp. and Sphagnum sp. along with three other moss species. Coverage of the mosses increased from 37% at 1 meter above ground level to 100% at 3 meters above ground level. Live moss biomass averaged about 1000 grams dry weight/m2 of rock face with a water content of about 80% of fresh weight. Nearly 9 liters of water was stored within the mosses per square meter of vertical rock face at 100% moss coverage. Water flow rate (as seepage) was continuous but very slow at about 1 milliliter/second per meter of horizontal width of vertical rock face. A variety of macroinvertebrates was sampled in the system including spiders, insects, earthworms and isopods. This complicated ecosystem with special adaptations for holding biomass, water and species diversity on a vertical plane against gravity may deserve special conservation status.
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