Epiphyte Colonisation of Fog Nets in Montane Forests of the Taita Hills, Kenya

Abstract

The dispersal ecology of tropical non-vascular epiphytes has rarely been experimentally investigated. We studied epiphyte colonisation on 1 × 1 m polyethene nets placed for four years at seven sites at different elevations in montane forests in the Taita Hills, Kenya. During the first year the nets were also used to measure fog deposition. We predicted that differences in growth conditions would affect colonisation and subsequent growth of non-vascular epiphytes and result in clear differences in epiphyte cover and biomass, and community composition among sites. After four years the nets were taken down for determination of epiphyte cover and biomass. The diversity of established liverworts and macrolichens was also examined. Many liverwort and macrolichen species established diverse communities on the nets placed in the moist upper-montane zone. This was in contrast with the situation in the drier lower-montane zone where only green algae and crustose lichens were able to colonise most nets. Light intensity was an important determinant of epiphyte community composition, with liverworts dominating on nets under closed forest canopies and lichens dominating at more open sites. Atmospheric moisture was also important, with lichens benefiting from abundant fog deposition at open and windy sites. The dry weight of epiphytes (per unit area) on lichen-dominated nets was greater than on liverwort-dominated nets, while the highest cover was generally observed on liverwort-dominated nets. Our results demonstrate that polyethylene nets can be effectively used to study colonisation of non-vascular epiphytes as well as the abiotic and biotic factors controlling epiphyte colonisation and community composition in tropical forests. The liverworts Acanthocoleus chrysophyllus and Diplasiolejeunea kraussiana were new additions to the Kenyan bryophyte flora.

Complex Interaction Networks Among Cyanolichens of a Tropical Biodiversity Hotspot

“…The Eastern Arc, together with other eastern African montane regions, including, for example, the Southern and Albertine Rift and the Ethiopian Highlands, form the Eastern Afromontane biodiversity hotspot ( Mittermeier et al, 2004 ). The study locations and vegetation of the area have been described in more detail by Enroth et al (2013 , 2019) , Stam et al (2020) , and Kaasalainen et al (2021) .…”

Modelling the carbon balance in bryophytes and lichens: Presentation of PoiCarb 1.0, a new model for explaining distribution patterns and predicting climate‐change effects

“…Although the dependence on VPD allows a reasonable estimation of drying speed in still and shady conditions, e.g., in forest understoreys, wind and direct radiation are additional climatic factors that can strongly affect drying (e.g., Uchida et al, 2002; Rice et al, 2011), which should be included to allow a wider application of the model. Moreover, additional inputs of water in the form of dew or fog can be very relevant for lichens and bryophytes, both in deserts (Lange et al, 2006; Lehnert et al, 2018; Jung et al, 2019) and in cloud forests (Stam et al, 2020). Including this type of water input in the model is already possible.…”