Evolution of wild and feral vines from the Ega river gallery forest (Basque country and Navarra, Spain) from 1995 to 2015

摘要

Aims: The present paper is focused on wild and feral grapevines from the Ega River gallery forest (Alder grove), one of the most important tributaries of the Ebro River. Since this area was preliminary prospected in 1995, it was our intention to assess the evolution of the ecosystem during this time.Methods and results: Ampelographic description of wild grapevines shows that all male plants had flowers with fully developed stamens and no gynoecium. No hermaphrodite individuals were detected. No virus infection and symptoms caused by Phylloxera on roots were detected. The Erineum strain of Colomerus vitis constitutes the main phytophagous arthropod. Damages caused by powdery and downy mildew were not lethal for the vines. Around 73% of the wild grapevine individuals found in 1995 had disappeared due to human impacts. The number of rootstocks and producer hybrids (French hybrids) had increased in this period by about 30%. Microvinification of wild berries yielded a wine with very high color intensity and total polyphenol index with a low pH.Conclusion: The wild grapevine population described has suffered a dramatic regression in the 20-year period between prospections, together with a significant increase of feral accessions thus endangering the endurance of the ecosystem and remaining wild grapevine.Significance and impact of the study?: Wild grapevines are a valuable genetic resource for the genetic improvement of cultivated vines. However, our study shows that human impacts and increasing pressure of feral accessions are threatening wild grapevine populations. IntroductionThe only Eurasian wild grapevine, Vitis vinifera L. subsp. sylvestris (Gmelin) Hegi, is considered an endangered subspecies in Europe (Di Vecchi-Staraz et al., 2009; Bodor et al., 2010). This is due to diverse anthropic impacts on natural habitats, like the exploitation of river-banks, public works, the infestation of downy and powdery mildew as well as the introduction of invasive vines, such as American rootstocks and producer hybrids used as a cultural method to prevent phylloxera infestation from the 19th century (Issler, 1938; Arnold, 2002; Ocete et al., 2007; Iriarte-Chiapusso et al., 2013).During the COST Action FA-1003 East-West Collaboration for Grapevine Diversity Exploration and Mobilization of Adaptive Traits for Breeding, developed between 2011 and 2014 (http://www.cost.eu/COST_Actions/fa/FA1003), the objectives were to increase the knowledge on wild grapevine populations by studying its ampelography, genetic pool, sanitary status, and enological characteristics. One of the main targets was to find some vines with potential resistance to pest and diseases, mainly to downy and powdery mildew.However, current viticulture is affected by an alarming genetic erosion process (This et al., 2001; González-Moreno et al., 2004; Esquinas-Alcázar, 2005; Gago et al., 2009) in the framework of climatic warming and markets globalization (Mira de Ordu?a, 2010; Mozell and Thach, 2014). In modern vineyards there are only a small number of clones with sanitary passport of the cultivars allowed within each Guarantee of Origin, so the genetic pool is declining alarmingly. Global warming will result in loss of acidity and color and together with globalization and open borders will increase the risk of introducing new pests and diseases, which might spread easily in vineyards with low genetic diversity. Due to those facts, Eurasian wild grapevine constitutes a useful phytogenetic resource to be used in breeding of cultivars and rootstocks for those new requirements, previously mentioned (Jones et al., 2005; Ocete et al., 2007; Popescu et al., 2013). On the other hand, this liana had important uses in the past (Ocete et al., 2011c) and nowadays it constitutes a relic element of river-bank forests, colluvial positions and coastal cliffs (Arnold, 2002).According to that idea, our attention was focused on Ega River, a tributary of Ebro River, situated in Northern Spain, because it conserves an extensive riparian vegetation with some disseminated population sites of wild grapevine, as it was shown in a preliminary prospection carried out by Ocete and Pérez (1995). The source of this river is located in álava province (Basque Country) south of the Cantabrian Mountain-Range, its length is 113 km, the average flow is 13.76 m3/s, draining an area of 1,497 km2 (fig. 1). Other plant populations within the Ebro River basin have been described previously (Martínez De Toda and Sancha, 1999; Ocete et al., 2003; Ocete et al., 2011b)SaveView full sizeExpand inlineCollapse inline Figure 1. Localization of Ega River. The aim of the present paper was to compare the number of wild vines registered in 1995 with those sampled in 2014 and to denounce the lack of a specific legislation for the conservation of this endangered taxon in the Iberian Peninsula. Also, to complete the description of the characteristics of their habitats according to associated plant communities,