*Abundance Code:   
   Average percent cover of a moss species on all rooftops sampled

    Very abundant = >40%
    Abundant = 10-40%
    Sparse = 1-10%
    Rare = <1%

Only one roof sampled was of cedar shakes, the rest were of asphalt shingles. Only Dicranoweisia cirrata and Bryum capillare were found on the cedar shakes. However, all the species found were present on asphalt shingles. On most rooftops sampled, there were typically fewer than 4 species present. Of these, the most common and abundant were Dicranoweisia cirrata, Bryum capillare, Tortula princeps. These species tend to form dense mats that cover large areas of the roof (see Part 1 of rooftop photos).

Racomitrium canescens var. ericoides (see Part 2 of rooftop photos) and Homalothecium aeneum were abundant, but occurred infrequently.  These species also have the ability to form large mats. Ceratodon purpureus was very commonly found on rooftops, but was in low abundance. This species is commonly found on many substrates and in many habitats. The remaining species were found infrequently, and in low abundance.  Antitrichia californica was found growing in heavily shaded areas of the roofs, while the other species were found in both exposed and shaded areas. This may suggest that different moss species grow in areas shaded by trees.

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