Conservation values, ecosystem services and disservices
We observed increased diversity but decreased naturalness score in the
crane-disturbed patches. This was due to the high cover of
early-successional natural pioneer and disturbance-tolerant species and
lower cover of generalists and competitors, especially Festuca
pseudovina , the dominant grass species of alkaline grasslands. Patches
of early-successional vegetation formed by grazing animals are integral
parts of the studied ecosystem, so in the current extent, these
early-successional patches do not pose a considerable conservation
problem (Deák et al. 2015, Valkó et al. 2017).
We evaluated the effects of crane biopedturbation on the forage quality
of grasslands using two proxies. Forage quality expressed by the
Balázs-score was lower in the disturbed patches compared to intact
grasslands, as crane ploughings are characterised by pioneer species
that sprout and dry out early in the season, so they do not provide
suitable forage in the summer and autumn (Balázs 1949). This implies
that in large extent, crane biopedturbation can be problematic for
grazing management. However, the negative consequences of decreased
overall forage quality in the disturbed patches can be counterbalanced
by the increased availability of forage plants in early spring. SLA is
another proxy of forage quality, as livestock tends to select species
with fresh, hydrated leaves characterised by large SLA (Balogh et al.
2021). We found that the disturbed patches were characterised by plants
with larger SLA. This can be important for grazing management especially
in the springtime, where the early-sprouting pioneer vegetation formed
on the disturbed patches can provide important complementary forage for
the livestock compared to the intact grasslands. The fresh sprouts of
short-lived graminoids (such as Bromus hordeaceus , Hordeum
hystrix and Poa bulbosa ) growing on crane-disturbed areas can
provide good forage for livestock in early spring (Molnár 2017).
We found that crane-disturbed areas provided floral resources for a
longer time and in larger quantity compared to intact grassland. This
can support the maintenance of insect diversity, especially pollinator
assemblages and palynivores (Bátori et al. 2020). This service has an
especially high conservation importance in grass-dominated habitats such
as the studied ecosystem with relatively few nectar-producing plants.
Similar phenomenon was reported on the burrows of Siberian marmots
(Marmota sibirica ), where the larger number of flowers and their
higher visibility attracted more pollinators compared to undisturbed
grasslands (Yoshihara et al. 2010).