Response of the N and P cycles of an old-growth montane forest in Ecuador to experimental low-level N and P amendments

Abstract Atmospheric nitrogen (N) and phosphorus (P) depositions are expected to increase in the tropics as a consequence of increasing human activities in the next decades. In the literature, it is frequently assumed that tropical montane forests are N-limited, while tropical lowland forests are P-limited. In a low-level N and P addition experiment, we determined the short-term response of N and P cycles in a north Andean montane forest on Palaeozoic shists and metasandstones at an elevation of 2100 m a.s.l. to increased N and P inputs. We evaluated experimental N, P and N + P additions (50 kg ha −1  yr −1 of N, 10 kg ha −1  yr −1 of P and 50 kg + 10 kg ha −1  yr −1 of N and P, respectivel…