Species richness and habitat diversification of bryophytes in submontane rain forest and fallows of Bolivia

Abstract

An analysis of corticolous bryophyte diversity on whole trees in primary rain forest and 4-15-y-old fallows at 500-650 m in the Alto Beni, Bolivia, showed a significantly decreased diversity of bryophyte families and moss species in the fallows. However, liverwort diversity was scarcely lower in the fallows, except in the very young (4 y old) ones. Fallows had a significantly higher percentage of smooth mat species (72%), which may reflect the warmer, drier microclimate in the fallows. About half of the bryophyte species of the rain forest had re-established in the 10-15-y-old fallows. The majority of these are ecological generalists and sun epiphytes; a small minority are shade epiphytes. Re-establishment of ecological specialists is slower than that of generalists. Species richness in the primary forest is highest in the canopy; in the fallows it is highest in the understorey due to striking shifts of species and specialized growth types (rough mats, fans, tails) towards lower heights on the trees in the fallows. These shifts correspond well with measured changes in air temperature and air humidity in the fallows as compared with the forest.

Bryophytes in fragments of Terra Firme forest on the great curve of the Xingu River, Pará state, Brazil 1 Part of Master's Dissertation of the first author.

“…In a study conducted in submontane forest, in Bolivia, Acebey et al (2003) realized that generalist species are apparently indifferent to forest destruction, while those with smaller niches (experts) seem to be less likely to survive the deforestation, as observed in this study where there was predominance of generalists. However, the large proportion of specialist (sun/share epiphytes), indicates that the fragments still have conditions for their establishment, mainly by their physiognomic conditions.…”

Vertical distribution of epiphytic bryophytes in an Indonesian rainforest

“…The recorded number of 146 epiphytic bryophyte species on eight understorey and eight canopy trees (estimated sampling completeness: 88% for canopy trees, 82% for understorey trees) is among the highest ever reported for tropical forests (e.g., Cornelissen and Ter Steege 1989;Montfoort and Ek 1990;Wolf 1993b;Acebey et al 2003). It is exceeded by a Costa Rican montane cloud forest (Gradstein et al 2001b), where growth of epiphytic bryophytes is enhanced by the frequent occurrence of fog.…”

“…These plants play an important role in the water balance and nutrient cycling of the forest (Pócs 1980;Nadkarni 1984;Hofstede et al 1994; but see Hölscher et al 2004), and function as substrate, food source and nesting material for numerous other rainforest organisms (e.g., Nadkarni and Matelson 1989;Yanoviak et al 2007). Several recent studies have described the species composition and richness of epiphytic bryophytes at different height levels on rainforest trees, as well as substrate preferences within the host trees (e.g., Cornelissen and Ter Steege 1989;Wolf 1993aWolf , b, 1996Gradstein et al 2001b;Holz et al 2002;Acebey et al 2003). Bark structure and microclimate were identified as key drivers of epiphytic bryophyte distribution within the forest.…”

“…Bark structure and microclimate were identified as key drivers of epiphytic bryophyte distribution within the forest. Due to the lack of a protective cuticle, bryophytes are sensitive indicators of climatic conditions (Gignac 2001;Léon-Vargas et al 2006;Zotz and Bader 2009), and environmental changes, e.g., in insolation or air humidity, may result in rapid community composition changes and vertical shifts of bryophyte assemblages on host trees (Barkman 1958;Acebey et al 2003;Frego 2007). In comparison, chemical bark factors seem to play a minor role in shaping epiphytic bryophyte distributions in rainforest (Frahm 1990) and also host specificity is rare among tropical bryophytes (Pócs 1982;Richards 1984;Kürschner 1990).…”

“…Based on life form (Mägdefrau 1982), shade epiphytes can be recognized by their exposed growth (e.g., tufts, pendants, carpets) that maximises light exposure while sun epiphytes are usually compact and prostrate to reduce water loss. Shade epiphytes, are thus generally less well adapted to desiccation than sun epiphytes and generalists, and are more seriously affected by forest disturbance (Gradstein 1992b(Gradstein , 2008Acebey et al 2003).…”