Estimating nitrogen risk to Himalayan forests using thresholds for lichen bioindicators

Ellis, Christopher J.; Steadman, Claudia E.; Vieno, Massimo ORCID: https://orcid.org/0000-0001-7741-9377; Chatterjee, Sudipto; Jones, Matthew R.; Negi, Sidharth; Pandey, Bishnu Prasad; Rai, Himanshu; Tshering, Dendup; Weerakoon, Gothamie; Wolseley, Pat; Reay, David; Sharma, Subodh; Sutton, Mark ORCID: https://orcid.org/0000-0002-6263-6341. 2022 Estimating nitrogen risk to Himalayan forests using thresholds for lichen bioindicators. Biological Conservation, 265, 109401. 9, pp. 10.1016/j.biocon.2021.109401

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Official URL: http://dx.doi.org/10.1016/j.biocon.2021.109401

Abstract/Summary

Himalayan forests are biodiverse and support the cultural and economic livelihoods of their human communities. They are bounded to the south by the Indo-Gangetic Plain, which has among the highest concentrations of atmospheric ammonia globally. This source of excess nitrogen pushes northwards into the Himalaya, generating concern that Himalayan forests will be impacted. To estimate the extent to which atmospheric nitrogen is impacting Himalayan forests we focussed on lichen epiphytes, which are a well-established bioindicator for atmospheric nitrogen pollution. First, we reviewed published literature describing nitrogen thresholds (critical levels and loads) at which lichen epiphytes are affected, identifying a mean and confidence intervals based on previous research conducted across a diverse set of biogeographic and ecological settings. Second, we used estimates from previously published atmospheric chemistry models (EMEP-WRF and UKCA-CLASSIC) projected to the Himalaya with contrasting spatial resolution and timescales to characterise model variability. Comparing the lichen epiphyte critical levels and loads with the atmospheric chemistry model projections, we created preliminary estimates of the extent to which Himalayan forests are impacted by excess nitrogen; this equated to c. 80–85% and c. 95–98% with respect to ammonia and total nitrogen deposition, respectively. Recognising that lichens are one of the most sensitive bioindicators for atmospheric nitrogen pollution, our new synthesis of previous studies on this topic generated concern that most Himalayan forests are at risk from excess nitrogen. This is a desk-based study that now requires verification through biological surveillance, for which we provide key recommendations.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1016/j.biocon.2021.109401
UKCEH and CEH Sections/Science Areas:	Atmospheric Chemistry and Effects (Science Area 2017-)
ISSN:	0006-3207
Additional Information. Not used in RCUK Gateway to Research.:	Open Access paper - full text available via Official URL link.
Additional Keywords:	ammonia, critical level, critical load, Himalayan forests, lichen, nitrogen pollution
NORA Subject Terms:	Ecology and Environment
Date made live:	01 Feb 2022 17:57 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/531872

Item Type:

Publication - Article

Digital Object Identifier (DOI):

10.1016/j.biocon.2021.109401

UKCEH and CEH Sections/Science Areas:

Atmospheric Chemistry and Effects (Science Area 2017-)

ISSN:

0006-3207

Additional Information. Not used in RCUK Gateway to Research.:

Open Access paper - full text available via Official URL link.

Additional Keywords:

ammonia, critical level, critical load, Himalayan forests, lichen, nitrogen pollution