Distribution, Ecology, Chorology and Phytocenology of Sweet Chestnut (Castanea sativa) in the Oltenia Region, Romania

Abstract

This article provides useful information on the distribution of sweet chestnut (Castanea sativa) and presents additional data on the ecology, chorology and phytocenology of the species in the Oltenia region, Romania, based on literary sources, herbaria and field observations. By providing accurate and detailed data, this study contributes significantly to the existing knowledge, as well as mapping efforts of the species at the European level. In the subspontaneous flora of the Oltenia region, the C. sativa species is found in sheltered resorts in the counties of Gorj (Glogova, Valea Perilor, Tismana, Pocruia, Polovragi, etc.) and Mehedinți (Comăneşti, Baia de Aramă, etc.), on mesobasic soils, balanced from a hydraulic point of view. The phytocenoses where this species grows are rich in southern elements (e.g., Cornus mas L., Cerasus avium (L.) Moench, Quercus dalechampii Ten., Tilia tomentosa Moench). They are included in the Castaneo-Quercetum Horvat 1938 association. In Romania, habitats that include areas occupied by sweet chestnut are classified within habitat R4141—Daco-Balkan forests of oak (Quercus petraea) and chestnut (C. sativa) with Genista tinctoria. This habitat has a very high biodiversity conservation value and ecological importance. According to the Natura 2000 directive, sweet chestnut forests are included in the habitat category 9260, which underlines the importance at the European level for biodiversity conservation.

1. Introduction

Castanea sativa is known at the European level as the only spontaneous species of the Castanea genus [1] and presents a remarkable evolutionary history in relation to other European forest tree species [2]. Its probable center of origin is northeastern Asia Minor and the Caucasus region [3], although possible Pleistocene glacial refugia have also been reported for southeastern Europe [4]. The present distribution ranges from northwestern Africa (e.g., Morocco) to northwestern Europe (southern England, Belgium) and from southwestern Asia (Turkey) to eastern Europe (e.g., Romania), the Caucasus (Georgia, Armenia) and the Caspian Sea [5]. In the later Middle Ages (the 11th to 16th centuries), chestnut became an essential source of food and timber in the Mediterranean and southern parts of Central Europe [6]. In its cultivated state, it was known for its high-quality wood, for its leaves that were used in empirical medicine, for its antitussive and bacteriostatic effects [7] and especially for its fruits [8]. It is possible that the Romans introduced the idea of systematic cultivation and use of chestnut; however, there is no evidence of systematic chestnut planting [5]. The greater interest in chestnut management for fruit production most likely developed after the Romans [5]. One of the largest known specimens of this species is the Castagno dei Cento Cavalli (Hundred Horses Chestnut), a monumental tree growing in the Carpineto area, Italy [9]. In Romania, C. sativa is mentioned in the specialized literature [10,11,12,13,14], and it is recorded in some papers as a wild taxon, appearing spontaneously in the Baia Mare and Gorj regions [15]. The natural distribution of chestnuts covers two principal centers, namely Maramures (the hilly foothills of Baia Mare) and Oltenia (the Subcarpathian hills of Oltenia in the Gorj, Mehedinti and Valcea counties) and several other small areas in the southeast of the Oriental Carpathians and the northwest and southwest of the Transylvanian plateau [11,12,13,14,16]. Some authors mention this taxon as a cultural relic [14,17], others as a rare species [11,18]. This article provides useful information on the distribution of sweet chestnuts and presents additional data on the ecology, chorology and phytocenology of the species in the Oltenia region, Romania, based on literary sources, herbaria and field observations.

2. Materials and Methods

Researched area. This paper analyzes the distribution of the C. sativa species in Oltenia. Oltenia is a region located in the southwestern part of Romania (43°40′ N lat in the south and 45°35′ N lat in the north and 22°–24°53′ E long in the west, respectively, east), which has a high diversity, both in terms of its natural conditions and of its natural and semi-natural flora and vegetation (Figure 1). From the altitudinal viewpoint, the range is quite high, 3 m in the Danube Alluvial Plain (at the confluence between the Olt and the Danube rivers) and 2519 m in the Parângul Mare Peak [19]. In this part of the country, we can find all of the zones and levels of vegetation, from the plain region level up to the alpine meadows. The areas occupied by chestnuts are cantoned at the Subcarpathian depression level. There, where the zonal vegetation is built up by sessile oak forests (Quercus dalechampii or Q. polycarpa), the vegetation forms having the highest floristic diversity among all the forests in Romania.

Climatic data. In the Oltenia region, the climate is predominantly continental, with some variations depending on the altitude and geographical position. Its average temperatures vary by season. During the summer, the temperatures can often exceed 30 °C, while in the winter they can drop below 0 °C, especially at the higher elevations. The average annual temperatures are generally moderate. Rainfall is generally moderate, with a maximum in May and June. They can vary according to the altitude and the geographical position, and in some areas, they can be influenced by the mountains and the local factors.

Methods. The data inserted in this paper are the result of processing information from the specialized literature, corroborating the personal data collected from the field and from the main herbaria in the country: Iași (University Herbarium “Alexandru Ioan Cuza”-I), Cluj-Napoca (University Herbarium “Babeş-Bolyai” Cluj-Napoca—CL), Bucharest (Herbarium of the Institute of Biology of the Romanian Academy—BUCA; herbarium of “D. Brândză” Botanical Garden in Bucharest—BUC), and Craiova (Herbarium of the University of Craiova—CRA). The acronyms of the consulted herbaria are in accordance with the Index Herbariorum (Thiers 2022+). The scientific names for the taxa used are according to the Plants of the World Online database (POWO 2023) for vascular plants, Index Fungorum for fungal species and EPPO Global Database for pests. In the study of vegetation, the research methods of the Central European school, developed by Braun–Blanquet, were used, and the association was named after Sanda et al. [20]. To analyze the floristic composition and the structure of a plant association, the Braun–Blanquet scale was used. For each taxon identified, the abundance and dominance were assessed using the following steps: r: <5 specimens/survey, with negligible coverage; +: ≤1% coverage; 1: 1–10% coverage; 2: 10–25% coverage; 3: 25–50% coverage; 4: 50–75% coverage; 5: 75–100% coverage. The observations were carried out during the vegetation period (from April to October). The classification codes for the sweet chestnut habitats: 9260 (Natura 2000); R4141 [21]; 41.57331 Pre-Carpathian chestnut-sessile oak forest (PAL. HAB 1999). Corolog 2010 program (RoBioAtlas 2023) was used to create surface distribution maps, correlated with the average annual temperatures and rainfall.

3. Results and Discussion

3.1. History

In Romania, the sweet chestnut grows naturally in the form of clumps or even massively in two areas only, in the country: the Subcarpathian depression of Oltenia (Tismana, Gureni, Hobita, Polovragi, Horezu), and in the Maramures area (Baia Mare, Baia Sprie, Top Tautii). The presence of this species in the two areas can be attributed to the Mediterranean influences, which are much more significant in these places (Figure 2a,b). According to some authors, the sweet chestnut existed in a spontaneous state even before the glaciation, occupying large areas in Romania, but shrank with the climate cooling, remaining in the two most important resorts: Tismana (Gorj) and the one near the village of Tăuții de Sus and to Tăuții Magheruș, which is included in the recreational area of Baia Mare city [18]. Chestnut forests are very rare in Romania, and their habitat is considered to have high conservation value [21]. According to Botu [22], there are different opinions regarding the presence of the chestnut on the territory of Romania: the chestnut has survived from the Tertiary up to now in the places sheltered from the cold currents; the species was introduced 2000 years ago during the Roman colonization of Dacia; or maybe the chestnut tree was introduced to the southern Romania by the Greek monks in the 14th century. In Oltenia, following the performed research, it appears that, in some areas, the sweet chestnut is represented by rare specimens, spread through the sessile oak forests (e.g., Glogova, Valea Perilor-Gorj and Comăneşti counties, Baia de Aramă-Mehedinți county), while, in others, it forms phytocenoses that can be included in the Castaneo-Quercetum Horvat I. 1938 association (e.g., Tismana, Pocruia, and Polovragi). Few secular copies are currently found in several monasteries in Oltenia (e.g., Polovragi, Horezu, and Turnu). The herbaria in Romania include material with this species from both cultivated and wild specimens. The oldest herbarium material in Oltenia dates from 1901 and was collected by A. Popovici from the Polovragi Hermitage. The evidence is provided by the 3 herbarium sheets from the “Alexandru Ioan Cuza” University Herbarium (I): I 7182, I 7183, I 7184. The research on this species can also be found in the specialized papers published at the beginning of the 20th century [23,24,25]. The studies have continued over time especially on the specimens grown for valuable fruits. In some regions of Oltenia, it is also cultivated as an ornamental plant, especially for its well-developed foliage and fruits.

3.2. Habitat and Coenology

C. sativa grows spontaneously at the level of the Subcarpathian depression in Oltenia, at altitudes ranging from 300 m to 600–700 m (e.g., near Cioclovina Hermitage, upstream of Tismana), being cantoned at the level of sheltered, sunny heights, with high degrees of inclination, on rich and fertile soils, where the climate is sub-Mediterranean, with humid and hot summers, with almost no cold winds. The sweet chestnut grows in good conditions, reaching appreciable sizes and occupying important areas. On the south-eastern slopes, where the soil is clay-calcareous and where there are still obvious remains of rocks that have not yet been disaggregated, the specimens have been identified with a diameter of 0.40–1.50 m and heights of 20–26 m. With reference to the habitat, according to Horvat et al. [26], the most favorable altitudinal range for C. sativa in the Balkan Peninsula is between 600 m and 900 m, corresponding to the growth zone of thermophilous deciduous oaks and the transition into the sub-Mediterranean growth zone, where the xerophilous and sclerophyllous species dominate. In Greece, the chestnut forests occur across a much wider altitudinal range, indicating that other factors such as soil acidity and the microclimatic conditions might be more important in determining their distribution [27].

In Oltenia there are 2 protected areas where the C. sativa species is present: Cornetul Pocruiei and the Tismana-Pocruia Forest. Regarding the climatic, edaphic and vegetation characteristics of the two areas (

Table 1. Classification of protected areas in the European Biogeographical Region.

Natural Protected Area	European Biogeographical Region	Natura 2000 Area (Area Code and Name)
Cornetul Pocruiei	Alpine	ROSCI 0129 Nordul Gorjului de Vest
Tismana—Pocruia Forest	Continental	ROSCI 0129 Nordul Gorjului de Vest

) it is found that there are differences in terms of soils and cenotic environment. The soils belong to the skeletal category, alternating with a calcareous substrate, in the case of the Cornetul Pocruiei reserve, and to the category of eumesobasic brown, acid brown and luvisols for the surfaces occupied by this species in the Tismana-Pocruia Forest protected area. Based on the analysis of information published in various specialized journals, it appears that this species prefers places near calcareous rocks. Velizarova [28] considers C. sativa to commonly grow on poor sandy to loamy soils on the slopes. It avoids the calcareous soils, but it can be found on the limestone substrate in several places in the Caucasus [29].

In terms of valuable species that are found in these areas, the situation is different due to the climatic conditions, the altitude, and the substrate on which they develop, as follows: in the Cornetul Pocruiei area, we find rare elements or elements that are significantly represented only in the SW part of Romania: Sorbus dacica Borbás, Dictamnus albus L., Sorbus graeca (Spach) Lodd. ex Schauer, Peltaria alliacea Jacq., Tamus communis L., Piptatherum virescens (Trin.) Boiss., Quercus pubescens Willd., Jovibarba heuffelii (Schott) A. et D. Löve, Allium flavum L., Syringa vulgaris L., Cotinus coggygria Scop., while in the “Tismana—Pocruia Forest” reserve, the value is given by the secular specimens of C. sativa (approximately 300–400 years old), next to which we meet the whole procession of the species characteristic of sessile oak forests in this part of the country. The classification in the European Biogeographical Region is different for the two protected areas (Table 1). These are integral parts of the Natura 2000 site: ROSCI 0129 North of Western Gorj.

The analysis of ecosystems within the boundaries of the two protected areas involved the correspondence approval of land use categories for the area of interest with the type of ecosystem to which that category belongs. Thus, several types of ecosystems were identified (forest, rocks, praticulture, scrublands), with different spatial weights and representations within the areas of interest (

Table 2. The correspondence of land use categories according to Corine Land Cover with the ecosystem types for the 2 protected areas *.

Corine Land Cover Code	Corine Land Cover Name	Ecosystems	Cornetul Pocruiei	Tismana—Pocruia Forest
313	Mixed forest	Forestry	x	x
332	Rocks	Rocks	x	-
321	Natural grassland	Praticulture	-	x
322	Meadow with small size shrubs	Praticulture	x	x
324	Transition area with shrubs	Bushes	x	x

* x = present in the area; - = absent in the area.

). These ecosystems are essential for the biodiversity and for the ecological functions they support.

The forest ecosystems are the most extensive, predominating in mountainous and hilly areas where the soil and climate conditions are favorable to tree growth, they provide habitat for the wildlife, contribute to the soil stability, regulate the microclimate, and are essential for the carbon sequestration. The rock ecosystems are narrower (Cornetul Pocruiei) and provide the habitat for rare and endemic species, contributing to the geological landscape and providing the reference points for the scientific research. Praticultural ecosystems are spread across the open areas, helping to maintain the biodiversity, and prevent the soil erosion, while the scrubland helps to restore the degraded soil and contributes to the ecological diversity. The scrublands are often found in transition areas between the grasslands and forests and can occupy significant areas in the areas of natural regeneration.

In the analysis of the floristic composition of Oltenia areas, the presence of acidophilic elements is noted. According to some authors, it is considered that these places would host caves with water that would ensure a favorable climate for the development of this species. The forests in which C. sativa grows very well in numerous specimens are assigned to the following cenotaxonomic units: Querco-Fagetea Br.-Bl. and Vlieger 1937 em. Borhidi 1996; Quercetalia roboris R. Tx. 1931; Castaneo-Quercion Soó 1962 em. Soó 1971—Castaneo-Quercetum Horvat I. 1938, and, if we refer to NATURA 2000, we can say that the areas included in the above-mentioned association are related to the habitat “9260 Forests of Castanea sativa”. These areas are present within the perimeter of protected natural area North Gorj West Site—ROSCI0129. It is a widespread forest habitat in the sub-Mediterranean areas, present in Romania only in isolation, in the Igniş-Gutâi Mountains, Zarand Mountains, Banat Mountains, Western Hills, Valcan Mountains, Căpăţânii Mountains, Cozia. In Oltenia, it is present in the Tismana-Pocruia forest and Cornetul Pocruiei. The species by which it can be recognized are C. sativa and Quercus polycarpa, Genista tinctoria, Festuca heterophylla, Hieracium umbellatum, Melampyrum nemorosum, Potentila erecta, Acer campestre and Pteridium aquilinum. Regarding the presence of the species in other regions, e.g., in Montenegro, the chestnut grows mainly in the Mediterranean area in the altitudinal zone of 200 m to 600 m (similarly to the altitude at which it is found in Oltenia), where it forms in mostly mixed forests with oak (Castaneo—Quercetum submediterraneum Wraber) or where the pure acidophilic chestnut stands grow [30], which reflects the sub-Mediterranean climatic influences in Montenegro, compared to the more continental climate of Oltenia. In both regions, the chestnut forms mixed forests with oak species, indicating comparable habitat types and similar ecological interactions. The arboreal layer comprises, in addition to the dominant species, other sporadic elements that complete the canopy of trees in these forests: Cerasus avium, Populus tremula, Carpinus betulus, Quercus dalechampii, Sorbus torminalis, Tilia platyphyllos, Betula pendula. The presence of the Carpinus betulus species attests to the fact that felling takes place in these forests, this species being known as the forest weed, but the felling is on a small scale. The shrub layer includes species characteristic of this area: Malus sylvestris, Pyrus pyraster, Cornus sanguinea, Crataegus monogyna, Rosa canina, Viburnum opulus, Corylus avellana, and Ligustrum vulgare. Among the lianas, we mention: Clematis vitalba, Vitis sylvestris or Hedera helix.

The grassy carpet has a weak coverage, being represented by a few acidophilic elements: Calamagrostis arundinacea, Genista tinctoria, Luzula luzuloides, and Agrostis capillaris.

The taxonomic classification and the abundance of plant species that justify the cenotaxonomic classification of these forests in the systems presented above are shown in

Table 3. The vegetation found in forests, taxonomic classification, and abundance.

Scientific Name	Botanic Family	Index of Abundance—Dominance
Dryopteris filix-mas (L.) Schott	Polypodiaceae	+
Athyrium filix-femina (L.) Roth		+
Asarum europaeum L.	Aristolochiaceae	1
Anemone nemorosa L.	Ranunculaceae	+–1
Clematis vitalba L.		+
Ranunculus polyanthemos L.		+
Betula pendula Roth	Betulaceae	+
Carpinus betulus L.		+
Corylus avellana L.	Corylaceae	+
Castanea sativa Mill.	Fagaceae	2–4
Quercus dalechampii Ten.		+–1
Lychnis viscaria L.	Caryophyllaceae	+
Moehringia trinervia (L.) Clairv.		+
Sedum maximum (L.) Hoffm.	Crassulaceae	+
Cerasus avium (L.) Moench	Rosaceae	+
Malus sylvestris (L.) Mill.		+
Pyrus pyraster (L.) Burgsd.		+
Crataegus monogyna Jacq.		+
Rosa canina L.		+
Sorbus torminalis (L.) Crantz		+
Genista tinctoria L.	Fabaceae	+
Dentaria bulbifera L.	Brassicaceae	+
Populus tremula L.	Salicaceae	+
Euphorbia amygdaloides L.	Euphorbiaceae	+
Mercurialis perennis L.		+
Gentiana asclepiadea L.	Gentianaceae	+
Acer pseudoplatanus L.	Aceraceae	+
Geranium phaeum L.	Geraniaceae	+
Impatiens noli-tangere Michx.	Balsaminaceae	+
Tilia platyphyllos Scop	Tiliaceae	+
Hedera helix L.	Araliaceae	+
Sanicula europaea L.	Apiaceae	+
Vitis sylvestris Blume	Vitaceae	+
Galium odoratum (L.) Scop.	Rubiaceae	+
Melittis melissophyllum	Lamiaceae	+
Stachys sylvatica L.		+
Symphytum cordatum Waldst. Et Kit. ex Willd.		+
Veronica officinalis L.	Scrophulariaceae	+
Viburnum opulus L.	Caprifoliaceae	+
Ligustrum vulgare L.	Oleaceae	+–1
Cirsium erisithales (Jacq.) Scop.	Asteraceae	+
Campanula persicifolia L.	Campanulaceae	+
Cephalanthera longifolia (L.) Fritsch	Orchidaceae	+
Luzula luzuloides (Lam.) Dandy et Wilmott	Juncaceae	+
Carex pilosa Scop.	Cyperaceae	+
Carex sylvatica Huds.		+
Agrostis capillaris L.	Poaceae	+
Brachypodium sylvaticum (Hudson) Beauv.		1
Calamagrostis arundinacea (L.) Roth		+–1
Festuca drymeja Mert. et W.D.J. Koch		+
Milium effusum Lour.		+

. The analysis of the floristic composition of these forests highlights the predominance of the species from Rosaceae and Poaceae families. These are followed at a distance by Ranunculaceae and Lamiaceae. The rest of the families are poorly represented as species. If the abundance-dominance of each species in the field is taken into account, it can be said that the taxa belonging to Fagaceae family are best represented, because they give the physiognomy of all the forests throughout the Subcarpathian depression in Oltenia.

Regarding the future threats to the ecosystems identified within the perimeter of the 2 protected areas where C. sativa grows, we can say that they will have a weak intensity (

Table 4. The threats to the elements of conservative interest.

Activities Taking Place within the Perimeter of Protected Area	Threat Code	Threat Name	Intensity	Cornetul Pocruiei	Tismana—Pocruia Forest
Grazing	A.04.02.05	Non-intensive grazing in a mixture of animals	Weak	x	x
Forestry exploitation (deforestation, sanitation, etc.)	B.02.02 B.02.05	Cleaning the forest Non-intensive wood production (leaving dead wood/not touching old trees)	Weak	-	x
	K04.02	Interspecific relationships of the flora: parasitism	Weak	x	x
Hunting	-	-	Weak	x	x
Tourism	-	-	Weak	x	x

x = present in the area; - = absent in the area.

) and these refer to grazing, logging, hunting and tourism. If we also consider the fact that the access to the Cornetul Pocruiei area is hampered by the inaccessibility of these places, we can say that future threats could be absent. However, climate change can have a significant impact on the health and productivity of this species, as reflected by the increasing temperatures, drought, changes in rainfall patterns, the increasing frequency and severity of extreme events, the increasing incidence of diseases and pests. The forests are among the ecosystems that are expected to be most affected by climate change and according to the scenarios made by Erturk and Aricak [31], for the future, it is shown that there will be a significant decrease in the suitable areas of distribution of chestnut populations in Kastamonu caused by the effects of climate change.

In using the ecological niche modeling approach, Gıraldo and Küçüker [32] suggest that climate change can significantly reduce the habitat suitability for C. sativa and this puts a substantial risk to the species, impacting not only the ecosystems but also the socio-economic aspects related to the chestnut fruit harvesting. Moreover, the environmental conditions are strongly influencing the plant diseases; therefore, the climate changes can also be considered drivers of disease outbreaks [33]. Diseases represent a threat to the sweet chestnut, and, in order to ensure a favorable conservation status of this species, these threats must be kept at a low level and the trees affected by Cryphonectria parasitica [34], a disease that can be favored by the climate changes, should be removed. According to Chira and Bolea [35], C. parasitica severely destroyed all mature chestnut stands in Tismana area. C. sativa is found to thrive in the specific habitats characterized by temperate climates, well-drained soils, and moderate altitudes. Its cenological characteristics highlight its role in various forest communities, contributing to the soil improvement and supporting the biodiversity. Conservation and sustainable management practices are essential to protect this valuable species and ensure its continued presence in the European forests, including the Oltenia region of Romania.

3.3. Chorology

In Oltenia, this species is known in several localities: Tismana, Pocruia, Topești, Boroșteni, Francești, Bâlta, Bâltișoara, Runcu, Dobrița, Vălari, Novaci, Polovraci, Izvarna, Costeni, Turceni, Gornovișa, Gureni, Hobita, Popești, Glogova, Valea Perilor (Gorj county), Cloșani, Padeș, Vălui-Orjești, Mărășești, Comănești, Baia de Aramă, Obârșia-Cloșani (Mehedinti county), Horezu and Turnu monasteries (Vâlcea county) (Figure 2a,b). In the specialized literature, it is mentioned from all the high hills and mountainous extensions of Vulcan and Mehedinți Mountains [23].

The distribution of C. sativa species in Oltenia is significantly influenced by the average annual temperatures, along with other ecological and soil factors (Figure 2a). The average annual temperatures are a crucial factor in the distribution and health of the sweet chestnut, being located in the areas with average temperatures between 8 and 11 °C. The distribution of sweet chestnut in Oltenia is closely related to the average annual temperatures, with preferences for the hilly and mountainous areas with warm summers and mild winters. According to the literature, the chestnut is a moderately thermophilic species and well adapted to the ecosystems with an annual average temperature between 8 and 15 °C, and the average monthly temperatures during its vegetative cycle above 6–8 °C [36,37]. The climate changes may negatively influence this distribution, but, through adaptation measures and proper management, the conservation and prosperity of sweet chestnut in the region can be ensured. The distribution of the C. sativa species in Oltenia is influenced not only by the average annual temperatures, but also by the average annual rainfall (Figure 2b). The chestnut survival is related to the combination of temperature and rainfall factors. Rainfall plays an essential role in providing the soil moisture, which is necessary for the growth and health of the chestnut tree. The sweet chestnut prefers well-drained and moist soils. The ideal annual rainfall for this species is between 800 and 1200 mm. The uniform distribution of rainfall throughout the year is crucial for the vegetative growth and fruiting of chestnut. The prolonged periods of drought can adversely affect the chestnut, leading to water stress for the trees, which can reduce their productivity and health. According to Conedera et al. [38], the chestnuts are very sensitive to the summer drought, and the lack of rainfall in the warm months is vital for their survival. Other authors agree that the average annual rainfall, as well as winter temperatures and rainfall, do impact the distribution of the chestnut [39].

The climate changes influence the rainfall patterns, so they can have a significant impact on the distribution and health of the sweet chestnut, underlining the need for climate monitoring and the adaptation measures to ensure the sustainability of this species. Iamshchikov [40] states that the species requires a minimum of rainfall, fallen during April–July, at least 25% of the annual total, and the rainfall values in that growing period could be a limiting factor for the sweet chestnut in Portugal. Understanding the environmental requirements and the potential impacts of climate change on these ecosystems is crucial for developing the effective conservation and management strategies to support the sustainable growth of the sweet chestnut trees in the region. From a chorological point of view, in Oltenia, the distribution of the species is favored by the climatic and edaphic conditions specific to the Subcarpathian and the hilly areas. Facing the challenges of the climate changes and diseases, the conservation efforts and sustainable management are essential to protect and maintain this valuable species. We can say that the need to protect these areas with C. sativa in Oltenia is supported on the one hand by the rarity of this plant, as it is protected by the Romanian Law of Fruit Farming No. 348/2003, and by the endemic character of sweet chestnut forests. The data obtained on the distribution of the sweet chestnut in Oltenia reflect both its ecological adaptability and the importance of human interventions in the conservation and expansion of this valuable species.

4. Conclusions

In conclusion, by providing accurate and detailed data on the distribution, ecology, chorology, and phytocenology of the sweet chestnut in Oltenia, this study contributes significantly to the existing knowledge and mapping the efforts of studying the species at the European level. It provides detailed maps of the sweet chestnut distribution in the Oltenia region, and these data can be integrated into the European databases to complement the continental maps. It also provides information on the specific habitats where the sweet chestnut thrives in Oltenia, thus contributing to a more granular understanding of the species’ ecological preferences. From the point of view of ecological and phytocenological analyses, this study explores the ecological relationships between the sweet chestnut and other plant species in Oltenia, providing valuable data on the associated biodiversity. Through the phytocoenological analysis, this study describes the structure of the plant communities where the sweet chestnut is found, with essential information for understanding the dynamics of local ecosystems. In terms of chorology and geographical distribution, this study provides data on the spatial distribution of the sweet chestnut in Oltenia, contributing to the knowledge of its geographical distribution at the European level, and identifies regional variations in the distribution of the sweet chestnut, which may help to identify local factors that are influencing its presence and abundance. The information can be integrated into the European research and the conservation projects, such as projects on the conservation of trees of commercial and ecological value; and the comparable data set can be used to extend and validate the distribution models at the European level.