Experimental evidence from Cantabrian mountain heathlands suggests new recommendations for management of Vaccinium myrtillus L

Abstract

Background: Management actions in mountain heathlands oriented to increasing the cover of Vaccinium myrtillus promote mowing of Calluna vulgaris to avoid competition. However, such action ignores the fact that plant-plant interactions range from competition to facilitation under different stress conditions. Aims: To test whether the interactions between these two species are related to competition or facilitation, which would change the perspective for their management in mountain heathlands. Methods: A total of 40 experimental plots located in a montane heathland (northern Spain) were selected. Calluna or Vaccinium plants were either cut at ground level or not cut, and plots were fertilized with nitrogen or not in a three-factorial design. Vegetative and reproductive shoot mass and length of the current year's shoots were estimated in two consecutive years for both species. Herbivory on Vaccinium by browsing ungulates was compared in control plots and plots where Calluna had been cut 2 yrs ago. Results: The two study species co-occurred in 72.4% of the sampled plots, although Calluna was more abundant. Vaccinium growth was greater in plots with Calluna than in plots where Calluna had been cut. Browsing on Vaccinium was also higher in plots were Calluna had been cut, and the effect of fertilization was only significant on the reproductive biomass of Calluna.Conclusions: Contrary to initial proposals, our results suggest that Vaccinium does not always benefit from the cutting of Calluna in heathlands. Thus, the management of Cantabrian mountain heathlands should consider maintaining Calluna in order to facilitate the growth of Vaccinium.

Continuous picking may increase bilberry yields

“…The findings of increased fruit production and fruit set of bilberry in our study suggest enhanced bilberry yields in areas under continuous picking. These results are not in accordance with several previous studies suggesting that biomass loss and mechanical damage due to the natural herbivory (Fernández-Calvo and Obeso 2004; Hegland et al 2005) or clipping cause reductions in bilberry fruit production and fruit set (Mathisen et al 2010;Nestby et al 2014;Pato et al 2016). A number of references support our findings of increased berry production and fruit set of bilberry after biomass loss.…”

“…Bilberry fruit production is associated with current annual shoot size (Tolvanen and Laine 1997;Fernández-Calvo and Obeso 2004) and is linked to the ability of bilberry to produce new growth after biomass loss. In this study bilberry lost annually less than 0.5% of its total standing biomass, which is far more than 50 times lower as compared to the 25% to 100% biomass loss applied by clipping in most of the studies on bilberry performance (Tolvanen et al 1994;Nestby et al 2014;Pato et al 2016). The recovery time after severe damage takes several years (Tolvanen et al 1994;Hautala et al 2008), during which vegetative recovery prevails and bilberry fruit production is postponed (Tolvanen et al 1993b;Nestby et al 2014).…”

Habitat-partitioning improves regional distribution models in multi-habitat species: a case study with the European bilberry

“…While the baseline model represents a higher proportion of the bilberry fundamental niche and, therefore, of the potential distribution of the species in the study area, the addition of habitat data informing on vegetation and, indirectly, on biotic interactions (Wisz et al 2013) allows the discrimination of a higher fraction of the realized niche, which is a better surrogate of species real occupancy. This can be inferred from the large differences in model outputs that were found between woodlands and heathlands, reflecting bilberry occupation of different niches in distinct habitats where competition interactions vary soundly, being part either of the woodland understory or the shrub community (Pato et al 2016), respectively.…”

Dynamics of rural landscapes in marginal areas of northern Spain: Past, present, and future

“…The other relevant mountain shrubland community is heathland, which hosts a relevant biodiversity of high conservation value (Fagúndez, ; Pato, Obeso, Ploquin, & Jiménez‐Alfaro, ). The conservation of this vegetation usually requires some management to rejuvenate them like grazing (by domestic and/or wild herbivores).…”