Effect of phosphorus and nitrogen on Sphagnum regeneration and growth: an experience from Patagonia

Abstract

Peatlands provide important ecosystem services which includes the production of fibers of Sphagnum moss that are used as a substrate in horticulture. Sphagnum fibers are greatly desired by international markets, resulting in an increase in their extraction, thus causing environmental deterioration through overexploitation, especially in Patagonian peatlands. Given this environmental problem, the present study aimed to evaluate the effect of the application of two fertilizers (NH₄NO₃ and NaH₂PO₄) on the regeneration and growth rate of Sphagnum magellanicum and Sphagnum falcatulum. An ex situ experiment was carried out in micro- and mesocosms extracted from three localities in Isla Grande de Chiloé, Los Lagos Region, Chile. The results reported that fertilization affects the development of Sphagnum moss, showing positive results on growth in height, while having a very limited effect on regeneration. Our data show a positive impact of some concentrations under natural climatic conditions. After three months, mesocosms with 10 g/m² of NH₄NO₃ (3.5 g N/m²) for S. falcatulum, and 5 g/m² of NaH₂PO₄ (1.3 g P/m²) for S. magellanicum, demonstrated statistically significant differences with respect to the control, with a mean growth of 15.2 mm and 5.6 mm respectively. According to the data, we can show that these treatments may be considered for the propagation of moss ex situ followed by reintroduction into the field. Field experiments are required to better understand the dynamics of nitrogen in Patagonian peatlands; nevertheless, these data suggest that attention be paid to nonpoint pollution of surface waters with nitrogen, because excessive inputs may have important effects on the growth of this natural resource.