Effect of spatial and temporal patterns of stress and disturbance intensities in a sub-Mediterranean grassland

Abstract

The present study examined a sub-Mediterranean pastoral system in the central Apennines (Italy) with a long history of\ud grazing, where winter cold stress is alternated with summer drought stress. The research goals were to ascertain whether\ud different floristic structures correspond to different stress conditions (xeric and semimesic), and whether peculiar functional\ud plant traits (such as avoidance and tolerance mechanisms) respond to stress/disturbance intensities, and understand how\ud vegetation reacts to changeable livestock pressure (through floristic and plant trait variations). Cluster analysis indicated that\ud separate communities develop under different stress intensities. Other analyses highlighted how avoidance strategies predominate within the pastoral system. Observations of grazed and ungrazed patches conducted in 10-m transects revealed spiny cushion formation in semimesic grassland, where a brief period of overgrazing occurs in late summer, causing variations in plant community structure. All these results confirm the importance of historical grazing and current land use, showing how small disturbances and stress variations cause ecosystem responses. Best practices for management were identified. In xeric conditions, it is advisable that the intensity of disturbance be lessened, while in semimesic grassland overgrazing should be forbidden during the dry period, because it could facilitate the development of spiny patches, and subsequent spread of Brachypodium rupestre

Effect of tall-grass invasion on the flowering-related functional pattern of submediterranean hay-meadows

“…It is well documented that the floristic composition and variability of pastures are strongly related both to the spatial variation of environmental features and constraints (Catorci & Gatti 2010;Blasi et al 2012;Ribeiro et al 2013) and to the management type (Catorci et al 2012c;Ibanez et al 2013). Moreover, abandonment of farming activities leads to the reduction of landscape complexity and promotes vegetation dynamics processes, a factor that could be detrimental for the conservation of biodiversity (Gargano et al 2012).…”

Pedo-climatic and land use preferences of Gentiana lutea subsp. lutea in central Italy

“…These constraints strongly affect the composition and distribution of plant communities, leading to the dominance of xerophylous species on south-facing slopes and of mesophilous species on the north-facing slopes (Burrascano et al 2013, Catorci et al 2012b). Moreover, the most mesophilous conditions were found on the bottom of flat valleys (Blasi et al 2012) and this may explain why impluvium (with deeper soils and consequent greater availability of water) emerged as the most suitable land form for the spread of G. lutea.…”

The interplay of land forms and disturbance intensity drive the floristic and functional changes in the dry Puna pastoral systems (southern Peruvian Andes)

“…Relevés were carried out in March 2009, since during this month it is possible to observe the highest number of species in conjunction with the end of the rainy season. It was stated that changes in species abundance and frequency is due to the way herbivores select forage according to relative palatability of leaves and the accessibility to their bite (Briske 1996;Grime 2001;Hunt 2001;Díaz et al 2007;Bertiller & Ares 2008;Catorci et al 2012b;Peco et al 2012). Thus, to better understand floristic and structural changes due to different disturbance intensity, the following plant traits were taken into consideration: life span (annual and perennial life history) and plant form/architecture (graminoids; non-graminoid; upright forb -plant with leaves distributed on upright stems or branches; hemirosulate forb -plant with leaves distributed both at ground level and raised from the ground; prostrate forb -plant with leaves distributed only at the ground level; tall shrub; dwarf shrub; cushion; succulent).…”