Long-term grazing effects on secondary succession of vegetation in old fields at the University Forest of Taxiarhis in Chalkidiki, northern Greece
Grazing is one of the most prevalent worldwide land uses, which can affect secondary succession of vegetation in abandoned fields. The aim of this study was to investigate the long-term effects of grazing on secondary succession of old fields in α mountain area of northern Greece. In order to meet this purpose, adjacent grazed mainly by goats and protected plots of an old field abandoned for 20 years were chosen in the village community of Taxiarchis, Chalkidiki, nortern Greece. In each of the two fields plant cover and biomass were measured. Plant species were classified into functional groups based on botanical family, life cycle, life form and photosynthetic pathway. It was found that grazing pressure was heavy. Plant cover and biomass were significantly decreased due to heavy grazing. Annual species were favoured at the expense of perennials, therophytes and geophytes at the expense of hemicryptophytes and warm season at the expense of cool season plants while woody species were suppressed. It is indicated that heavy grazing pressure by goats leads to earlier stages of secondary succession of the vegetation in old fields.
The effect of drought on the water relations of annual forage species in a low elevation grassland
Water is a restrictive factor that affects the growth and the productivity of forage species in the Mediterranean region. The aim of this study was to investigate the water relations under water deficit conditions and the drought adaptation ecophysiological mechanisms of two annual forage species, Hordeum murinum (grass) and Medicago αrabica (legume). The experiment was conducted in the spring – early summer of 2010 in a low elevation grassland. The midday leaf water potential (Ψ), the stomatal conductance (gs) and the transpiration rate (E) were measured, while the Vapor Pressure Deficit (VPD) over the canopy and the leaf Relative Water Content (RWC) were estimated. Different responses under water deficit conditions were evident between the two species. During the growing season, high VPD (2,5-4,1kPa) values dominated and, thus, both species presented different transpiration demands. In the end of the growing season, M. arabica exhibited lower Ψ (-2,84 MPa) and higher RWC (60,64%) in relation to H. murinum (-2,30 MPa, 56.27%, respectively). The annual grass H. murinum completed earlier its biological cycle, having higher water losses than M. arabica which reached the critical threshold point later (middle of June) and adapted better to water deficit conditions. Our results suggest that, M. arabica probably displays ecophysiological mechanisms that enable it to continue to grow, even under intense water deficit conditions.
Effect of the addition of nitrogen and phosphorus in the structure of a seminatural grassland of early secondary succession stage
Nitrogen (N), and phosphorus (P) are the soil resources that most commonly affect primary productivity and as such determine the structure of plant communities in terrestrial ecosystems. The aim of this study was to examine the effects of these two resources on the primary productivity and structure (composition of functional groups – grasses, legumes and forbs) in a seminatural grassland of early secondary succession stage. The results showed that N was a limiting resource, and its increased availability tended to maximize the primary productivity of the grassland and favor the functional group of grasses. On the other hand legumes, having the ability to fix atmospheric N2, exhibited an increased competitiveness when N was limiting, particularly following water and P additions.
Cultivation and production of aromatic plants in Greece: present situation, possibilities and prospects
The herbs are an integral component of everyday life and culture in all over the world for centuries. These plants are used in pharmaceuticals, in cosmetics, in cooking and in recent years, in food technology as antioxidants. The Greek flora is rich in native herbs and the climatic and soil conditions are prevailing the possibility of their cultivation. The cultivation of aromatic plants declined in the midnineties, but it seems that nowadays reoccurred. The most important species that are cultivated nowdays are the dictamnus, oregano, mountain tea and chamomile. Particularly the cultivation of chamomile has a significant increase. The current trend for healthy food has increased the demand of quality plant products in combination with changes in the CAP (Common Agricultural Policy), can be a springboard for the replacement of conventional crops with alternative crops, aromatic and medicinal plants.
The role of transhumance in the evolution of vegetation and landscape: a case study in Northern Greece (Vermio mountain)
Transhumance is a traditional farming system which involves sheep and goats, common in many countries of the Mediterranean basin. This seasonal movement of animals results to a better exploitation of the native vegetation of intermediate and high elevation rangelands (spring- autumn) and low elevation grasslands (autumn – winter). In Greece, transhumance uses native vegetation of mountainous rangelands 5-7 months a year. The aim of this paper was the study of the evolution of transhumant livestock system in Vermion mountain and the effect on the structure of the vegetation and the landscape. The rangelands of Vermion mountain are used as summer pastures mainly by the ‘Sarakatsanoi’ of Thessaly. A significant reduction of those pastures was found. Also, both the number of transhumant families and the number of transhumant sheep and goat declined during the last 50 years. Reduced transhumant livestock system may be due to various socio-economic factors that have significantly influenced the lifestyle of farmers. The gradual undergrazing of natural mountainous rangelands of Vermio mountain resulted in the diversification of their structure and plant composition.