Wild grapevine (Vitis vinifera subsp. sylvestris) in Germany: Is reintroduction a viable approach?

Vitis vinifera subsp. sylvestris is an endangered species in large parts of Central Europe. In the upper
Rhine floodplains, Germany, less than 100 individuals have survived until the middle of the 20th cen-
tury. Local reintroduction approaches began in 1967 and increased the number of individuals to 1.075
in 2018. However, the current population status and the success of these long-term reintroduction
efforts are, so far, unknown, although they represent an important basis for the future conservation of
V. vinifera subsp. sylvestris.
For this study, all known sites of V. vinifera subsp. sylvestris. in the upper Rhine valley were
surveyed in 2017–2018. The vitality of the individuals, their growing conditions, and local threats were
assessed to evaluate establishment chances, and time series of vitality data (2012, 2013, and 2018) were
analyzed for reintroduction sites in Leimersheim, Lingenfeld, and Römerberg. In the most recent survey
in 2018, we found 482 individuals from previous reintroduction efforts (1974 to 2016). Overall, 55% of
the individuals introduced since 2012 had died. Only 16% of 456 planted individuals (for which vitality
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data and planting year were available) showed high vitality and reproduction potential and were
therefore considered established. The remaining 84% (mostly planted in 2016) had not reached the
canopy and were therefore subjected to unsuitable light conditions, with low to medium vitality. The
number of adult, reproducing individuals of the total population had decreased. The risk factors that
have led to the massive decline of the species are still existing in 2018. In particular, in the massively
degraded Upper Rhine floodplains, the species-specific habitat requirements are largely no longer met
and must be restored as part of renaturation measures to facilitate the establishment of this species.
Focus should be placed on the creation of natural flooding dynamics in selected areas.
Currently, the reintroduction of V. vinifera subsp. sylvestris. is particularly difficult due to a lack of
suitable habitats. Added to this are the long establishment period, the late reproductive age, dioecy, and
hybridization with Vitis cultivars, wild Vitis individuals, and vine rootstocks. Due to a combination of
these factors, this species is threatened with extinction in Germany and must be protected through
appropriate nature conservation and forestry strategies. The success of reintroduction efforts, the effect-
tiveness of protective measures, and the status of the population must be monitored regularly.