High tolerance of subalpine grassland to long-term ozone exposure is independent of N input and climatic drivers

Environ Pollut. 2014 Jun:189:161-8. doi: 10.1016/j.envpol.2014.02.032. Epub 2014 Mar 22.

Abstract

In a seven-year study, we tested effects of increased N and O3 deposition and climatic conditions on biomass of subalpine grassland. Ozone risk was assessed as exposure (AOT40) and as stomatal flux (POD0,1). We hypothesized that productivity is higher under N- and lower under O3 deposition, with interactions with climatic conditions. Aboveground biomass was best correlated with growing-degree days for May (GDDMay). Nitrogen deposition increased biomass up to 60% in the highest treatment, and 30% in the lowest addition. Also belowground biomass showed a positive N-response. Ozone enrichment had no effect on biomass, and no interaction between O3 and N was observed. Growth response to N deposition was not correlated to GDDMay or precipitation, but indicated a cumulative effect over time. Productivity of subalpine grassland is tolerant to increasing ozone exposure, independent of N input and climatic drivers. N deposition rates at current critical loads, strongly increase the grassland yield.

Keywords: Air pollution; Critical load/level; Nitrogen; Phytotoxic ozone dose POD; Productivity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptation, Physiological / physiology*
  • Air Pollutants / toxicity*
  • Air Pollution / statistics & numerical data
  • Biomass
  • Carex Plant / physiology
  • Climate*
  • Ecosystem*
  • Environment
  • Festuca / physiology
  • Nitrogen / analysis*
  • Ozone / toxicity*

Substances

  • Air Pollutants
  • Ozone
  • Nitrogen