Seasonal changes of forage quality in phrygranic rangelands of westem Crete in relation to altitude
Phrygana are the most extensive type of rangelands in Crete. They cover one third of the island and occur everywhere Ποιη the see-level up to the alpine zone. Their production is undergoing seasonal changes both in quantity and in quality due to climatic variation. The changes in quality were studied along an elevation gradient in westem Crete. Three study sites were selected at the low, middle and high ecological zones with altitudes of 25m, 675m and 1200m, respectively. Sampling was curried out at the end of each season, beginning in the autumn of the growing period 1987-88. The following results were obtained,
a. crude protein content ofthe phryganic live phytomass was increased from the autumn (9%) to the winter (13%) and then declined till the end of summer. Herbs were richer and ranged frοm 14% at the low site to about 20% at the high site during autumn.
b. cell walls (NDF) followed an opposite trend. They varied from 30% in the winter to more than 50% at the end of summer. Phrygana were always richer than herbs.
Relationships between woody and herbaceous plants in silvopastoral systems
Agroforestry and especially silvopastolisιn is an old land use which recently came into scene for ecological and economic reasons. Studies have shown its beneficial ecological role for stabilisation and improvement of degraded pastures through the biodiversity and ιnicroclimatic conditions that are created. The function of these systems is affected by the intereelations and competition between woody and herbaceous plants ιnainly for light, water and nutrients. Herbaceous plants seem to suppress tree seedlings, especially in extreme conditions. Woody plants however result in the reduction of herbage production as they ιnature due to lack of light, favour the shade tolerant species and affect seed production. On the other hand, herbage production seems to be higher and of better quality under shade than in open pastures. Competition for nutrients is significant at the seedlings stage but it is reduced Jater on as roots grow in different soil layers as well as with fertilisation. Finally, forest floor suppresses herbaceous species but this depends on the leaf size and their decomposition rate.
Effects of grazing and spacing on growth dynamic of some woody fodder plants
The leaf growth dynamic and forage production in relation to the effect of spacing and grazing by sheep were
studied in the woody species Robinia pseudoacacia, Gleditsia triacanthos, Amorpha fruticosa and Morus alba. The study was conducted in a seιni-arid area with poor sandy soil, in northem Greece. The species were establishment in three different spacings (1.5X1.5m, 2.5Χ2.5m and 3.5X3.5m). Plants were one year-old at the time of planting and kept in the shrubby form by cutting back during the winter. Grazing was applied two times during the summer period (early July and late August) of 1992, 1993 and 1994. They were measured: the leaf growth rate, forage production, water potential and stomatal conductance. It was found that growth rate was not affected by spacing. The highest forage production per unit area was accomplished in the 1.5X1.5m spacing while the highest forage production per shrub was in the 3.5X3.5m spacing. Robinia presented the highest 1eaf growth rate (0.14cm/day) and forage production (394kg/ha). The influence of grazing increased leaf RGR and maintained the production at high leνels during summer. Morus was well adapted to the specific environment and to grazing.
Range sites of calcareous grasslands in western Macedonia, Greece
In this paper, the factors that determine the range sites haνe been investigated in limestone grasslands located in the prefectures of Kozani, Florina and Pella of westem Macedonia, Greece. The different variations of the calcareous substrate support in general dry soils with νery low water holding capacity. The small differences among the 18 study sites were deterrnined by factors related to general climate, relief-microclimate and parent rock-soil. The most important of them, however, were the physical soil characteristics while the soil chemical properties had no particular effect. lt was found that the principal factor related to grassland production was the amount of surface rocks. As a result, three range sites were identified based on the cover of surface rocks ( <30, 30- 50 and >50%) which supported different herbage production ( >1200 500-1200 and <50 kg/ha respectively) and, therefore, different grazing capacity (>1, 0.9-0.5 and <0.5 sheep/ha/year respectively).
V egetation and production of the subalpine rangelands of the mountain Pangeon
Species composition and aerial biomass production were studied in representative sites of the subalpine region ( 1250-1950m) of mountain Pangeon in order to identify the types and subtypes of rangelands that occur there. They were identified 12 subtypes from which 8 were grasslands and 4 were shrublands. The aerial biomass production was greater on Ν, NW sites and lower on tops and S sites. It ranged from 140 g/m2 to 674g/m2. The grasslands of 1500- 1650 m elevation were the most productive.
