Daniel Gómez-García

Does wild boar rooting affect livestock grazing areas in alpine grasslands

Interactions between traditional livestock management practices and wildlife activities are important in the conservation of many mountain ecosystems including the summer rangelands in the Spanish Central Pyrenees, where rooting by wild boar (Sus scrofa) is a large disturbance that can reduce the amount of area available to grazing livestock. This study explored the likely impact of wild boar rooting on Pyrenean grasslands. It quantified the extent of wild boar rooting in livestock grazing areas and determined whether wild boars selected or avoided areas depending on the type of livestock and stocking rates. Wild boar rooting affected 16% of livestock grazing area and occurred in sites that were grazed by cattle, rather than by sheep. In addition, a preference for areas that had intermediate stocking rates was found. The relationship between the increase in the number of wild boars and trends in livestock management suggests that the extent of wild boar rooting will increase especially in cattle grazing areas, and therefore, the area available for cattle grazing in Pyrenean mountain rangelands would decrease significantly.

Occurrence and intensity of wild boar disturbances, effects on the physical and chemical soil properties of alpine grasslands

Background and aimsPhysical and chemical soil properties determine local plant conditions and resources, affecting plants’ ability to respond to disturbances. In alpine grasslands, wild boar disturbances occur at different intensities, what may affect differently their soil properties. Alpine soils from five contrasted plant communities were explored within and outside disturbances, accounting for an overall and community scale effect. Additionally, we analysed the effect of disturbance intensity on soil NO3--N and NH4+-N.MethodsSoils were analyzed for physical (bulk density, moisture content and electrical conductivity), and chemical properties (pH, total N and C, oxidizable C, C:N ratio, available K, P, Ca2+, Na+ and Mg2+). Resin bags were used to compare the effect of the disturbance occurrence and intensity on soil NO3--N and NH4+-N.ResultsBulk density, total N and NO3--N concentration were significantly higher in disturbed areas, while soil moisture, C:N, NH4+-N, Na+, Mg2+ and Ca2+ concentrations were significantly lower. However, low disturbance intensity reduced NO3--N and increased NH4+-N concentrations.ConclusionsWild boar occurrence and intensity strongly alter physical and chemical conditions of alpine soils, increasing soil compaction, and altering the availability of N forms. These changes may affect most plant species, thus affecting the structure and dynamics of alpine plant communities.

Wild-boar disturbance increases nutrient and C stores of geophytes in subalpine grasslands

UNLABELLED PREMISE OF THE STUDY Wild-boar soil disturbance (i.e., rooting) increases the abundance of some species of geophytes (i.e., plants with underground renewal buds) in upland meadows. However, the mechanisms that could lead to such enhanced prevalence remain unexplored. • METHODS We analyzed the effects of wild-boar disturbance on the size, nutrient (N, P, K, C, and total ash), and nonstructural carbohydrate (soluble sugars, starch plus fructans, and total nonstructural carbohydrate) content of the storage organs of five taxa of upland geophytes. Results were explored in relation to the nutrient availability (total N, available P, and K) in the soil. • KEY RESULTS Wild-boar rooting increased the size and the nutrient content of the storage organs of geophytes. Such enhanced storage was further promoted by rooting recurrence and intensity. Although we could not detect a direct impact of rooting on soil nutrient concentrations, plants were clearly N limited and such limitation was ameliorated in areas rooted by wild boar. Furthermore, plant-soil interactions for N were different in rooted areas, where plant N-concentrations responded positively to soil N. • CONCLUSIONS Geophytes growing in rooted areas have an increased nutrient value, which may promote the revisit of wild boars to previously rooted areas, with further positive feed-back effects on plant quality. This plant-animal interaction may shape upland geophyte communities.

Ice cave reveals environmental forcing of long-term Pyrenean tree line dynamics

Tree lines are supposed to react sensitively to the current global change. However, the lack of a long‐term (millennial) perspective on tree line shifts in the Pyrenees prevents understanding the underlying ecosystem dynamics and processes. We combine multiproxy palaeoecological analyses (fossil pollen, spores, conifer stomata, plant macrofossils, and ordination) from an outstanding ice cave deposit located in the alpine belt c. 200 m above current tree line (Armena‐A294 Ice Cave, 2,238 m a.s.l.), to assess for the first time in the Pyrenees, tree line dynamics, and ecosystem resilience to climate changes 5,700–2,200 (cal.) years ago. The tree line ecotone was located at the cave altitude from 5,700 to 4,650 cal year bp, when vegetation consisted of open Pinus uncinata Ramond ex DC and Betula spp. Woodlands and timberline were very close to the site. Subsequently, tree line slightly raised and timberline reached the ice cave altitude, exceeding its todays uppermost limit by c. 300–400 m during more than four centuries (4,650 and 4,200 cal year bp) at the end of the Holocene Thermal Maximum. After 4,200 cal year bp, alpine tundra communities dominated by Dryas octopetala L. expanded while tree line descended, most likely as a consequence of the Neoglacial cooling. Prehistoric livestock raising likely reinforced climate cooling impacts at 3,450–3,250 cal year bp. Finally, a tree line ecotone developed around the cave that was on its turn replaced by alpine communities during the past 2,000 years. Synthesis. The long‐term Pyrenean tree line ecotone sensitivity suggests that rising temperatures will trigger future P. uncinata and Betula expansions to higher elevations, replacing arctic–alpine plant species. Climate change is causing the rapid melting of the cave ice; rescue investigations would be urgently needed to exploit its unique ecological information.