Managing for species composition or diversity? Pastoral and free grazing systems in alkali steppes

Abstract

A B S T R A C TFree grazing and herding of local breeds have a long tradition in management and conservation of extended grassland habitats such as alkali steppes. However, there is a lack in studies evaluating the effects of grazing types and regimes on the vegetation composition and functional diversity. We selected Artemisia steppes, a widespread type of alkali steppes, to study the changes of vegetation composition and diversity along a grazing intensity gradient. We recorded the cover of vascular plant species, in altogether 150, 2 Â 2-m-sized plots of 15 steppes in 2014. The steppes were managed by free grazing, traditional Hungarian Grey cattle grazing (low, moderate and high intensity), or by heavy grazing (Grey cattle and sheep, and additional donkey grazing). We answered the following questions: (i) How do the species richness, diversity and species evenness change along the increasing intensity of grazing? (ii) How does the grazing affect the functional trait composition along the intensity gradient? (iii) How similar is the composition and diversity of free grazed steppes to the pastoral grazed ones? We detected no significant differences in species richness but a humped-back curve with a peak at the medium grazing intensity was found for the Shannon diversity, evenness and the proportion of subordinated target species. The highest Rao's quadratic entropy was found for low intensity grazing. The lowest scores of multi-trait functional evenness were detected for the medium grazing intensity, while for multi-trait functional divergence both medium and very high intensity displayed low scores. The intensity of grazing was negatively correlated with the plant height and LDMC, while positively with the rosette forming, SLA, thousand-seed weights, terminal velocity and flowering period. Our results suggest that for the highest functional diversity a low intensity traditional cattle grazing is recommended. A medium grazing intensity should be chosen to have the highest proportion of subordinated target species of conservation interest, and the highest species diversity and evenness. Our findings suggest that free grazing and lowintensity traditional grazing can be substitutive to each other; various grazing intensities from low to medium, alternating in space and/or time can be appropriate to maintain high compositional diversity.

Water Buffaloes grazing behaviour at the Lake Kerkini National Park, Northern Greece

“…The intensity of livestock grazing highly influences the impact on grasslands (Papanastasis et al 1998, 2016. Long-term heavy grazing of water buffaloes in the study area may have affected the cover and the botanical composition of grasslands, but to our knowledge, there is no published evidence for this.…”

“…Traditional grazing by local breeds should be considered as one of the most adequate options to achieve a proper management of biodiversity and related ecosystem services in grasslands , Jerrentrup et al 2015. Most information concerning low intensity grazing systems are provided in relation to cattle and/or sheep grazing (Metera et al 2010, Jerrentrup et al 2015, Török et al 2016, while information on other types of grazing animals, such as Mediterranean river buffaloes, are rather scarce (but see Napolitano et al 2007).…”

Influence of Grazing Intensity on Swamp Plant Communities in the Tropical Montane Wetland Ecosystems, Nilgiris, Southern India

“…For example, across a large study region, Haynes et al (2012) demonstrated that grazing strongly modified plant community composition due to the selection of palatable plants, with species diversity declining under increased grazing intensity. Similarly, Török et al (2016) found a marked difference in species composition under very high grazing intensity. Conversely, Golodets et al (2010) identified species similarity increasing between vegetation on sites recently from which grazing had been recently excluded.…”

“…Grazing is a disturbance which can threaten the ability of plant communities to maintain plant species richness and abundance and lead to an altered species composition (Olff and Ritchie, 1998;Walker et al, 2013;Yan et al, 2013;Török et al, 2016). Grazing alters plant diversity through mechanisms that influence local plant colonization ability and extinction dynamics (Olff and Ritchie, 1998;Alofs et al, 2014).…”

Tradeoffs between forage quality and soil fertility: Lessons from Himalayan rangelands

“…Additionally, excessive livestock often are slaughtered in autumn to ensure moderate grazing intensity during the winter when rangeland productivity is low (Galvin, 2009). These traditional management regimes are intended not only to ensure sustainable yield but also to keep forage digestibility high and promote diversity in the rangeland plant community (Glindemann et al, 2009;Teague et al, 2013;Török et al, 2016).…”