In 1969 N and P fertilizer experiments were carried out on the Westerheide (The Netherlands) to investigate the growth of Calluna vulgaris. In 1981 the floristic composition of the experimental plots was analyzed. Repeated nitrogen treatment of 28 kg • ha 1 . yr I resulted in dramatic replacement of Calluna vulgaris by Festuca ovina as a dominant. Phosphorus treatments did not result in such a change. The amounts of nitrogen applied in this experiment are similar to those that will be available during the first years following the dying off of Calluna vulgaris as result of a heather beetle infestation. It is hypothesized that a heather beetle infestation alone may result in a similar replacement of Calluna vulgaris by grass species.

Although the unproductive uplands ('dead lands') in Java are now reafforested or terraced, the crop productivity is still low in particular on volcanic soils. Sources of erosion are briefly discussed. It was concluded that the low productivity of upland farming systems was caused by low inputs and not by surface erosion and a redirection of soil conservation policy, planning and research is required. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Experimental fields were established at three sites on different soil types in Dutch heathlands, where grass species have become dominant, in order to find methods for re-establishment of an ericoid dwarf-shrub heath. Treatments included mowing, mowing and cutting for hay, ploughing, milling, sod cutting and burning.Re-establishment of ericoid dwarf shrubs was only observed after creation of gaps or patches of open soil. The results after nine years for two of the sites and six years for the other site indicate that sod cutting is the most suitable method provided that the mineral top soil is not removed or disturbed. More profound removal of the sod including mineral soil causes a delay in re-establishment of ericoid dwarf shrubs and an increase of grasses.Factors that may explain different responses to gap creation including availability of seeds, soil moisture, soil fertility and plant survival strategies are briefly discussed. Abbreviations: Calluna = Calluna vulgaris,

Changes over a period of 10 30 years in the vegetation of some INTRODUCTI ONMost of the ericaceous vegetation in Europe is situated in man-made heathlands. These heathlands are maintained by management practices, such as burning, mowing or cutting sods, which remove the standing crop and in the last case also the organic matter accumulated in the Ao-horizon (Gimingham, 1972). These practices lead to the development of even-aged 283 Biol. Conserz~.

Abstract. Effects of milling, mowing and sod cutting on productivity in a Deschampsia grass heath and a Molinia‐Deschampsia grass heath were studied from 1977 to 1986. The sum of above‐ground biomass, litter and accumulated humified matter (TOM) in both types was ca. 70 ton/ha and the primary productivity 3–5 ton ha‐1yr‐1. Mulching did not affect the annual production. Sod cutting reduced the productivity to 1–2 ton ha‐1yr‐1; on the Molinia‐Deschampsia site this reduction lasted for at least a decade, while the Deschampsia heath started to recover from sod cutting soon and increased in productivity again. Annual mowing both with and without removal of hay reduced the production as well, particularly on the Molinia‐Deschampsia heath. Lower production was either the result of phosphorus depletion ‐ Molinia‐Deschampsia site ‐ or nitrogen depletion ‐ Deschampsia site. In the mowing treatments there was also a depletion of carbohydrate reserves.