Plant and fungal use in Tusheti , Khevsureti , and Pshavi , Sakartvelo ( Republic of Georgia ) , Caucasus

Rainer W. Bussmann1*, Narel Y. Paniagua-Zambrana2, Shalva Sikharulidze3, Zaal Kikvidze4, David Kikodze3, David Tchelidze3, Ketevan Batsatsashvili3, Robert E. Hart1 1 William L. Brown Center, Missouri Botanical Garden, P.O. Box 299, St. Louis, MO 63166-0299, United States 2 Herbario Nacional de Bolivia, Instituto de Ecología-UMSA, Campus Universitario, Cota Cota Calle 27, La Paz, Bolivia 3 Institute of Botany and Bakuriani Alpine Botanical Garden, Ilia State University, Botanikuri 1, 0105 Tbilisi, Georgia 4 4-D Research Institute, Ilia State University, Cholokasvili 5, 0162 Tbilisi, Georgia


Introduction
Pshav-Khevsureti and Tusheti (Fig. 1) are located on slopes of the main Caucasus range, with elevations from 1250 to 4493 meters.The climate is generally cool with a median yearly temperature of about 5°C.The hottest month is July with mean temperatures between 13-15°C.The region lies in the drier part of the Caucaus and receives only about 450-900 mm of annual rainfall, which especially at higher altitudes falls mostly as snow.Dagestan borders Tusheti in the east, while Chechnya and Ingushetia border the region in the north, and the Georgian province of Kaheti borders it in the south.The highest peaks in this part of the Caucauss are Tebulo (4492 m), Komito (4261 m), Dano (4174 m), and Diklosmta (4285 m).Tusheti harbors a wide variety of ecozones, and its very high biodiversity [1,2].
Pshav-Khevsureti and Tusheti are known for Late Bronze and Early Iron Age settlements, starting in the third century BC.Earliest written accounts go back to Ptolemaus [1].
The population of the region consists of Khevsur, Pshav, and Tush ethnic groups, the latter divided into Tsova Tushs and Chaghma Tushs, which are however ethnographically almost identical.Linguistically, the Chaghma Tushs speak a dialect close to Khevsurian, Mokhevian, and Pshavian, which all belong to the Pkhovian group of Georgian dialects.The Tsova Tushs speak a distinct language -Tsova Tushetian / Batsbian in their homes, and a Georgian dialect similar to Kahetian in more official settings [1,3].
In this study, we documented traditional plant use in Tusheti, Pshavi, and Khevsureti, also elucidating culturally important species, and hypothesized that (i) plant use knowledge in general would be higher in isolated high elevation communities, and that (ii) use of home gardens would be much more restricted to lower elevation settings.

Ethnobotanical interviews
Fieldwork was conducted in Khevsureti, Khevi, and Tusheti in July-August 2013, July-August 2014, and September-October 2015.Interviews using semi-structured Informant consensus.Informant consensus (IFC) for a given use-category (UC) was calculated as the number of use-reports (UR) (the use of one species for a specific purpose) minus the number of taxa (t) over the number of use-reports minus one: N UR − N t / N UR − 1 Plant relative importance.Species were ranked by three metrics: (i) cultural importance value (CI), the sum within species across all plant-uses of the number of informants reporting a plant-use divided by the number of informants reporting the plant; (ii) use-diversity (UD), the Shannon index of uses (calculated with the R package "vegan", [9]); and (iii) use-value (UV), the number of reports of a species over total number of informants asked in a region [10].

Results
In the present study, we encountered 317 plant species belonging to 203 genera of 80 families being used in the study area (Tab.1).Of these, 197 species were exclusively wild-harvested, 73 were grown in homegardens, and 47 were both grown in gardens and sourced in the wild.
Among areas within the study area, plants and their uses showed only partial overlap in the region, with a wider divergence in uses (Fig. 2).Between the two major areas, Khevsureti and Tusheti, the bulk of unique uses were reported from the generally higher elevation communities within the Tusheti area.

Informant consensus
Number of UR was highest across all communities in the food and medicinal usecategories (Fig. 4, Tab. 2), and IFC generally increased with the number of UR.However, some communities/categories with fewer UR showed a high degree of IC, either within a certain category (e.g., in Omalo community of plants used for construction) or across all categories (e.g., in Dino community).Certain uses, particularly poison and veterinary, were rare and/or geographically limited.

Discussion
Plant species, and uses, found in our study, showed clear relations to the wider Caucasus -Asia Minor -Balkans cultural complex, showing broad overlap with other studies, forming part of what Biscotti and Pieroni [11] described as "hidden Mediterranean diet".The species number found was, however, far higher than in most published studies from either the region or the wider Mediterranean and Eurasia region, with species counts between 44-330 [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30].The highest number in these studies was, however, derived from a combination of food plants all over Italy [18].The species numbers used in the study region are, however, comparable, because, although the surface area of the study region was bigger than the areas of some of the comparative studies, the number of interviewees in each village was normally low (often only 1-2), since many villages were depopulated.The overall number of interviewees was, however, either similar, or lower in the study region.Just across the Caucasus range, in Dagestan, with a very similar cultural background, the use of wild vegetables was much lower than in the study region (24 species only), while all reported uses coincided [31].The lower number of participants in Dagestan (20, in only one village) might help to explain the divergence.The research time in Dagestan was, however, much longer.The number of participants in Tusheti, the closest study region in Georgia, was only about twice as high., but all reported uses coincided [31].The much larger incidence of wild plant use for food in Tusheti might stem from the long isolation and high altitude location of the whole region, where agriculture and home gardening are relatively recent arrivals after the construction of the main access road in the 1970s.However, a very similar structure of plant use could be observed all over Georgia [32,33].Interestingly, medicinal plant species tended to coincide much more with other studies in the region [14,[34][35][36][37][38][39][40][41][42][43].
Tab. 3 The 95th percentile species ranked by cultural importance.The use of Rhododendron sp. to clear beer, and as medicinal infusion, is rather unique, given the reports of toxicity of the species which extend from ancient Greek and Chinese sources [44,45] to modern cases of poisoning [46].In the main center of diversity of the genus, careful use of certain species has been reported for food and medicine [47][48][49][50].The protection of relatively common species like Rhododendron caucasicum, closely linked to its traditional use, has been shown as essential for alpine treelines often formed by Betula litwinowii [51].

Scientific name
The reported food use of use of acorns of Quercus iberica links to regional food use history, as various species of Quercus have been reported as food from Turkey since prehistorian times [52].

Conclusions
For Tusheti-Khevsureti, geographic differences and elevation structure both explain what kinds of ways people use plants and what plants they use.However, there was a degree of variance in the plants and uses informants reported that was not explained by these factors.
The genetic erosion of traditional crop varieties was previously of little concern for the mountainous areas of Georgia.These served as a repository of ancient crops until the 1990s.Recently, the most prevalent cause for genetic erosion of traditional crop varieties is the outmigration in mountain regions as reaction to the harsh economic conditions and lack of modern infrastructure [3,[53][54][55].The shift from traditional cultivars to modern high-yielding crops, which took place in the lowlands much earlier, began in mountain villages towards the end of Soviet occupation.The closure of frontiers, e.g., to Chechnya and Dagestan greatly reduced market access Tab. 4 The 95th percentile species ranked by use-diversity.[56].Across Georgia, abandoned terraces indicate where grain was formerly grown.Many old barns still contain clay lined grain storage baskets made from Salix sp., which quite often contain old grains.However, essentially no cereals have been grown in the surveyed high altitude regions of Georgia for decades, according to all participants recalling cereal cultivation at all.Nowadays, villagers buy wheat to distil alcohol or to bake bread, or buy commercial beer making mixtures to brew their own beer [3].The maintenance of home gardens in Georgia serves as socio-ecological memory, like in many other regions [57,58], and is an irreplaceable tool to maintain Georgian culture.This represents not only a reflectance of growing popularity of gardening and gathering [59,60], but cultural survival.The tremendous variety of useful plants in the study region might well provide a reservoir for food security, similar to the Balkans [61].However, climate change is affecting both floristic diversity in the wild and in gardens, both in the Caucasus as well as continent wide [62,63].The rise of tourism in Georgia might help to maintain the very diverse food uses in the region, while medicinal uses are most likely going to be a memory of the past soon.

Scientific name
Tab. 5 The 95th percentile species ranked by use-value.

Fig. 2
Fig. 2 Proportional Euler diagrams of plants and usage shared among areas within Tusheti-Khevsureti.

Fig. 3
Fig.3 Informants from the Tusheti-Khevsureti region ordered by their distance in plants reported (a,b) and in uses reported (c,d).

Fig. 4
Fig.4 Informant consensus plotted over number of use-reports for each use-category among informant communities.