Changes in herbage production in relation to shrub cover during the early spring period in semi-arid Mediterranean rangelands

The present study is a contribution towards the assessment of the changes in herbage production in relation to shrub cover during the early spring period in semi-arid Mediterranean rangelands when herbage quantity is low but quality is high. The study was conducted Lagadas county, northern Greece during spring 2004. In the study area four types of vegetation were identified, namely abandoned field, grassland, open and dense shrubland with 0%, 5%, 36% and 49% shrub cover respectively. Sward height, live matter yield and sward bulk density were measured in 15 and 30 April and 15 May. Ιn the Laboratory live matter was sorted by hand from dead matter and then into legumes and other species (grasses and forbs) in order to assess their dry matter contents. In the non-legume fraction the nitrogen and phosphorus nutrient indices were also calculated. It was found that live matter generally decreased as shrub cover increased during the early spring season. On the contrary the growth rate did not differ significantly between the four types. Sward height was significantly higher when shrub cover was maximum in 30 April, whereas sward bulk density was significantly higher when no shrubs occurred during April. Finally, live matter yield was positively related to nitrogen and phosphorus nutrient status, while P supply had an indirect effect on live matter yield through the increase in N index.