Image: Wikimedia Commons.

Image: Wikimedia Commons.

Continuing with my ele­mental theme of recent posts, when air is men­tioned then the atmo­sphere ought to be one of the first things to come to mind. And it is. But more than just provid­ing essen­tial nutri­ents /elements /chemicals such as oxy­gen (for res­pir­a­tion) and car­bon diox­ide (for pho­to­syn­thesis), it also provides nitro­gen (which is made avail­able to plants after its fix­a­tion and oxid­a­tion to such com­pounds as nitrate) and oxides of sul­phur that help to provide essen­tial sulph­ates (when the acid rain rains down). But the air con­tains more than those com­pounds and in some envir­on­ments can be an import­ant source of water, too, e.g. cloud forests. Almost in an act of faith – well, I knew I’d read it some­where, but couldn’t remem­ber where – and over sev­eral years, I have told my stu­dents that clouds (col­loids of liquid water in a gaseous phase) in cloud forests were a major – and dir­ect – source of water for the trees in that eco­sys­tem. Fortunately, that claim was never chal­lenged by the stu­dents (which I attrib­ute to their hum­bling belief that their older and wiser plant bio­logy mentor would not delib­er­ately mis­lead them…). But, and thanks to the work of Greg Goldsmith et al., fears that any botan­ical sleight of hand would be dis­covered under even the mild­est of inter­rog­a­tions have now been allayed because they show that cloud-based ‘leaf wet­ting’ does per­mit the dir­ect uptake of water accu­mu­lated on leaf sur­faces into the leaves them­selves. So much for the ‘physiology’, as for the ‘eco­logy’ they also indic­ate that such foliar uptake improves plant water status dur­ing the dry sea­son. At least that is the case in ‘trop­ical mont­ane cloud forests’ in Costa Rica, which I’m almost cer­tain is the par­tic­u­lar eco­sys­tem I had – no doubt pres­ci­ently – in mind in my lectures…


Nigel Chaffey. ORCID 0000-0002-4231-9082

Nigel is a botanist and full-time academic at Bath Spa University (Bath, near Bristol, UK). As News Editor for the Annals of Botany he contributes the monthly Plant Cuttings column to that august international botanical organ. His main goal is to inform (hopefully, in an educational, and entertaining way...) about plants and plant-people interactions.

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