Atmospheric N deposition is expected to accelerate with rapid economic development in China. Epiphytic bryophytes play an important role in the biodiversity, biomass, and nutrient cycling of the whole forest ecosystem in the Ailao Mountains. Few studies have looked at the impacts of enhanced N deposition on epiphytic bryophytes, despite their being much more sensitive to atmospheric N pollution compared with ground-rooted plants.
Prof. Liu Wenyao and his research team of Xishuangbanna Tropical Botanical Garden (XTBG) conducted a field manipulation experiment to study the effects of N deposition on epiphytic bryophytes in a subtropical montane cloud forest (24°32′N, 101°01′E) in Ailao Mountain National Nature Reserve in southwestern China.
The aims of the study were to: (1) assess the potential response of epiphytic bryophytes to simulated increases in N deposition, from the community level down to the impact on physiology (including species richness and cover, growth and vitality, concentrations of tissue C, N, and P, and chlorophyll content) in the montane cloud forest; (2) reveal the possible mechanisms underlying those responses; (3) find sensitive epiphytic bryophytes which may be used as indicators for assessing the degree of N pollution in the future; and (4) assess the recovery rate of bryophyte communities after cessation of N addition.
The study found that epiphytic bryophytes are highly sensitive to N addition and often difficult to recover once they have been destroyed from a locality, and they appear in many cases to be more vulnerable than co-occurring plants such as the forest trees that support them. They determined that excess N deposition significantly reduced cover and species richness of epiphytic bryophytes in a subtropical montane cloud forest in southwestern China.
In the preliminary exploration looking at how an epiphytic bryophyte community responds to enhanced N input, the researchers found that several bryophyte species, B. himalayana, B. ovistipula, and H. flabellatum, were very sensitive to increasing N deposition with potential as candidates in atmospheric nitrogen monitoring.
The study entitled “Response of epiphytic bryophytes to simulated N deposition in a subtropical montane cloud forest in southwestern China” has been published online in Oecologia, DOI:10.1007/s00442-012-2341-9