Epiphytes improve host plant water use by microenvironment modification

Abstract

Summary 1.Epiphytes have the potential to modify the canopy environments in which they grow. Accurately evaluating the impact of epiphytes can be challenging, since plants without epiphytes may also otherwise differ from host plants, and experimental removal is impractical and difficult to replicate in many forests. 2. We studied the impacts of epiphytes (primarily fruticose lichens and Tillandsia spp.) on host plants (Eulychnia saint-pieana and Caesalpinia spinosa) in two fog ecosystems in Chile (Pan de Azucar) and Peru (Atiquipa). These desert ecosystems sustain very high epiphyte loads and depend heavily on fog-water inputs. Using a combination of artificial substrates and epiphyte removals, we show significant impacts of epiphytes on their host plants. 3. The presence of epiphytes reduced throughfall volumes, reducing fog and rainfall inputs to the soil beneath host plant canopies. 4. Soil moisture loss rate was increased below cacti after removal of epiphytes from sun-facing but not shade-facing branches. This suggests epiphyte effects on hosts are microclimatic. 5. Epiphytes also buffered temperature fluctuations and reduced daytime vapour pressure deficit. 6. Epiphytes can have strong effects on host plant ecophysiology and forest ecosystem processes, making them an important component for models and studies of canopy environments.

Forests, atmospheric water and an uncertain future: the new biology of the global water cycle

“…Furthermore, trees can use moisture stored in their stems when their needs exceed uptake-such stored water can provide 20%-30% of transpired water and this is typically replaced at night, though such transpiration may be maintained over several days, even with a growing moisture deficit (Čermák et al 2007). In some locations trees capture, and then re-evaporate, significant moisture from clouds, fog or dew (Holder 2004;Fu et al 2016;)-a process often boosted by epiphytic vegetation (Holscher et al 2004;Villegas et al 2008;Stanton et al 2014). While water on leaf surfaces inhibits transpiration, the foliage of plants in wet environments tend to dry rapidly (Smith and McClean 1989;O'Brien et al 2004).…”

Broad-scale distribution of epiphytic hair lichens correlates more with climate and nitrogen deposition than with forest structure

“…If several factors change simultaneously, we could expect synergetic responses that could dramatically disrupt ecological functions of hair lichens in forests. This may have cascading negative effects on other organisms such as reindeer, canopy-living invertebrates, and passerine birds (Pettersson et al 1995) and adversely impact water and nutrient cycling (e.g., Knops et al 1996;Stanton et al 2014).…”

“…Hair lichens have important functions in forests. They participate in nutrient and water cycling, provide habitat and food for animals, and constitute a significant part of the winter diet for caribou and reindeer (subspecies of Rangifer tarandus (Linnaeus, 1758); Hauck 2011; Stanton et al 2014;. Hair lichens are useful indicators of forest ecosystem integrity and have strongly declined in areas with atmospheric pollution (Kuusinen et al 1990;Bruteig 1993) and intensive forestry (Esseen et al 1996).…”

“…Therefore, many lichens have recovered locally, but emissions of nitrogen are still high or increasing with a negative impact on lichens inhabiting oligotrophic environments such as Bryoria and Usnea (van Herk et al 2003;Hultengren et al 2004). Hair lichens are particularly sensitive to pollution and climate change, as their large surface area to mass ratios filter moisture and elements from the air (e.g., Knops et al 1996;Stanton et al 2014). In Sweden, nitrogen deposition shows a steep south-north gradient and exceeds 10 kg N·ha −1 ·year −1 in southern regions (Pihl Karlsson et al 2011).…”

Evaluación del Proyecto Epífitas del Parque Histórico Guayaquil

“…Así mismo, las epí-Litas amortiguan las fluctuaciones de temperaturas y pueden ayudar a reducir la evaporación durante las horas de luz (Stanton, et al, 2014). El epifitismo puede ocurrir tanto en la base de los troncos de árboles, como en el dosel de árboles de más de 50 m. de altura.…”