Questions: What is the impact on non-target species of restoration methods to establish Calluna vulgaris on grass-dominated moorlands?
Location: A Nardus stricta-dominated moorland in Wales and a Molinia caerulea-dominated moorland in Northern England, UK.
Methods: Two replicated experiments were established on grass-dominated moorlands. The treatments comprised disturbance (rotavation and trampling by animals), addition of Calluna seed, and three different grazing regimes, together with a no grazing control.
Results: The creation of bare ground and addition of seed increased the establishment of the desired dominant shrub, Calluna vulgaris. In the Nardus sward, rotavation and trampling were equally successful in establishing Calluna, but rotavation was more successful in the Molinia sward. Rotavation inhibited the growth of competitive grass species better than trampling. However, the disturbance techniques were detrimental to other components of the plant community, causing a decline in the cover of desirable species such as Vaccinium myrtillus and other dwarf shrub species and a small increase in the occurrence of undesirable species such as Juncus effusus. Grazing also controlled competitive grass species: Festuca ovina decreased in cover at a grazing intensity of 1.5 ewes/ha; Molinia caerulea and Agrostis spp. declined when cattle were included in the grazing regime, but increased in cover when ungrazed or when grazed at 1.5 ewes/ha.
Conclusions: When restoration concentrates on the establishment of one or a few species, it is important to monitor how the techniques used affect the rest of the plant community – particularly with regard to losses of desirable species or increases in undesirable species.