Short-term study of effects of fertilisation and cutting treatments on the vegetation dynamics of mountain heathlands in Spain.

摘要

The influence of management and nutrient availability on the vegetation dynamics of heathlands characterised by Calluna vulgaris and Erica tetralix were studied in three mountain sites in Northern Spain. A total of 90 plots (1 m2 each) received different combinations of cutting and twice the estimated background atmospheric deposition of nitrogen (56 kg ha-1 yr-1). One of the two dominant ericaceous species was selectively cut by hand at ground level and their regeneration compared in the presence or absence of the other. The results after 2 years showed significant effects of the fertiliser on the vegetation cover, mainly by favouring perennial herbaceous species. There were less noteworthy effects on the number of flowers and on the annual growth of the ericaceous species. It is concluded that, in the short term, increased nutrients alone, at twice the estimated current atmospheric deposition for the area, will not alter significantly the composition of the mountain heathlands. However, once the stands reach the mature phase, the capacity of the community to regenerate after a severe disturbance diminishes. A drastic impact, such as cutting may not result in re-growth of the same shrub species but in replacement by herbaceous species, which will also benefit from the increased nutrients..