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2015 Changes in landscape composition of differently irrigated hay meadows in an arid mountain region — Riedener E, Melliger RL, Rusterholz H-P & Baur B — Applied Vegetation Science 18: 242–251 doi> 10.1111/avsc.12141

Questions
Does the recent change from traditional to sprinkler irrigation result in alterations in the surrounding landscape of species-rich hay meadows in an arid Swiss mountain region? Are landscape composition and landscape heterogeneity important determinants of plant diversity in these meadows?

Location
Southwestern Switzerland.

Methods
We surveyed vascular plant species in six traditionally and six sprinkler-irrigated hay meadows. Plant species were divided into grassland specialists and generalists. Individual landscape traits were assessed in circular areas with radii of 50 and 100 m around each meadow in a field survey. Aerial photographs were used to measure the percentage area covered by different habitat types in the present and prior to the installation of sprinklers at the same spatial scale as in the field surveys. The potential effects of irrigation technique and present-day landscape features on the plant diversity and species composition of hay meadows were examined with GLM and NMDS.

Results
Landscape composition was more diverse for traditionally than for sprinkler-irrigated meadows, but did not differ prior to the installation of sprinklers. Total plant species richness and the number of specialists were negatively affected by the distance to the closest haystack. Generalists were positively influenced by a variety of different small-scale landscape traits in the surroundings, whereas the percentage area covered by woodland had a negative effect. Finally, hay meadows irrigated with sprinklers had an increased number of generalist plant species.

Conclusions
This study showed that the small-scale surroundings, and to some extent the type of irrigation, are important for the conservation of plant diversity of these meadows. Furthermore, the study suggests that the installation of sprinklers was associated with a homogenization of the landscape, which facilitates land use. Extensive management should be promoted by compensation payments for farmers to prevent intensification.

Keywords: generalists - grassland specialists - landscape traits - land-use change - semi-natural grassland - small-scale landscape - Valais (Switzerland) - water management

2014 Land-use abandonment owing to irrigation cessation affects the biodiversity of hay meadows in an arid mountain region — Riedener E, Rusterholz H-P & Baur B — Agriculture, Ecosystems & Environment 185: 144–152 doi> 10.1016/j.agee.2013.12.023

In arid regions, irrigation is required to secure agricultural production including the production of hay. The Valais, a dry inner alpine valley of Switzerland, has a long tradition of meadow irrigation. However, in the 20th century irrigation was stopped on marginal, poorly accessible areas usually accompanied by the entire abandonment of these meadows. The aim of this study was to examine the consequences of land-use abandonment resulting from the cessation of irrigation for the biodiversity of species-rich hay meadows in the Valais. We compared soil characteristics and species richness and composition, habitat specificity and functional traits of plants and gastropods of three serial stages of succession (each five hay meadows, early abandoned meadows and young forests). Soil moisture was lower in young forests than in the other two stages. Soil nitrogen content decreased following abandonment, which was due to the cessation of fertilization. The three successional stages did not differ in plant species richness but harboured distinct plant communities. Gastropod richness increased with progressive succession and species composition of hay meadows differed from those of the two other stages. The proportion of grassland (plants) and open-land (gastropods) species decreased following abandonment. Furthermore, meadow abandonment led to an increase in the height of non-woody plant species, a later start of seed shedding, a change in the type of plant reproduction and an increase in the shell size of gastropods. In conclusion, this study showed that extensive land-use, which is strongly linked to irrigation, is required for the characteristic species-rich hay meadows of this arid mountain region.

Keywords: land-use change - grassland succession - plants - gastropods - soil characteristics - Valais (Switzerland)

2014 Do different irrigation techniques affect the small-scale patterns of plant diversity and soil characteristics in mountain hay meadows? — Melliger RL, Riedener E, Rusterholz H-P & Baur B — Plant Ecology 215: 1037–1046 doi> 10.1007/s11258-014-0360-9

Traditional management practices are suggested to maintain species-rich grasslands. In the Valais, an arid region of Switzerland, hay meadows are traditionally irrigated using open water channels. However, in the past decades this irrigation technique has been increasingly replaced by sprinkler irrigation, which is assumed to result in a more homogeneous water distribution than open water channels. This study examined whether the change in irrigation technique affected the small-scale distribution of plants and soil characteristics in hay meadows in the Valais. Three plots consisting of 13 subplots of increasing size (0.1 × 0.1 to 6.4 × 6.4 m) were installed in six traditionally and six sprinkler-irrigated meadows. In all subplots, plant species richness and soil characteristics [moisture, pH, total organic nitrogen, organic matter content (SOM), total and plant available phosphorus] were recorded. The type of irrigation technique did not affect the shape of the plant species–area relationship. In none of the meadows did the species area–curves reach the asymptote within the range of plot sizes examined. Mantel r statistics showed that spatial autocorrelation in the soil characteristics examined was low and their small-scale distributions were not influenced by the irrigation technique except for soil pH and SOM. Our results indicate a pronounced small-scale heterogeneity in the distribution of plant species and soil characteristics for both types of irrigation technique. This can partly be explained by the fact that sprinklers distribute the water less homogeneously than commonly assumed. As applied in the Valais, sprinkler irrigation does not reduce the spatial heterogeneity and hence biodiversity of hay meadows.

Keywords: semi-natural grassland - water management - land use change - species–area relationship - spatial autocorrelation - Valais (Switzerland)

2013 Effects of different irrigation systems on the biodiversity of species-rich hay meadows — Riedener E, Rusterholz H-P & Baur B — Agriculture, Ecosystems & Environment 164: 62–69 doi> 10.1016/j.agee.2012.09.020

The maintenance of traditional management practices is essential for the conservation of the biodiversity of semi-natural grasslands including species-rich hay meadows. In the canton Valais (Switzerland), hay meadows are traditionally irrigated using open water channels. However, since the 1980s, this labour intensive irrigation technique has been increasingly replaced by sprinkler irrigation. This study examined whether the different irrigation techniques (traditional vs. sprinkler) influence the local biodiversity of species-rich hay meadows. In particular, the diversity and composition of plant and gastropod species of eight traditionally irrigated meadows were compared with those of eight sprinkler-irrigated meadows. It was also assessed whether the species of either meadow type differed in functional traits. A high plant species richness was found in the meadows investigated. The study showed that the diversity and composition of plant and gastropod species of hay meadows were not affected by the change in irrigation technique 8–18 years ago. However, a lower grass/forb-ratio was observed in traditionally than in sprinkler-irrigated meadows. Furthermore, irrigation technique affected the leaf distribution and the onset of seed shedding in plants. Thus, the change in the irrigation technique altered only some aspects of biodiversity. Therefore, irrigation system alone does not represent the major factor affecting the biodiversity of hay meadows investigated.

Keywords: semi-natural grassland - water management - land-use change - functional traits - plants - gastropods