THE BULGARIAN FLORA ONLINE
THE BULGARIAN FLORA ONLINE
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Sweet Chestnut.
Castanea sativa L.
PROTECTED species in Bulgaria.
The Sweet chestnut tree is a mediumlarge deciduous tree that may reach 30-35 m. When cultivated, the tree is long-living (up to 1 000 years) and may also reach a significant girth (up to 12 m at breast height). The bark is brown-greyish and often has net-shaped venations with deep furrows or fissures. Leaves are oblong-lanceolate (8-25 cm long, 5-9 cm broad) with a dentate-crenate margin and a brighter green upper leaf surface. This species tree is monoecious and flowers develop in late June to July and may be pollinated by wind (more usual in case of dry weather during flowering) or insects (dominating in wet weather conditions). Male flowers are gathered in catkins (5 to 15 cm in length) whereas female flowers are usually positioned at the base of the male ones in the upper part of the current year’s shoots. By autumn the female flowers develop into spiny cupules (commonly called bur) containing 3-7 brownish nuts that are shed during (September)-October. Some cultivars, especially the varieties of the Marron-group, develop only one large nut per cupule (rarely up to three). The nut is an achene composed of two skins; the external part is shiny brown (pericarp) and the internal is a pellicle adhering to the fruit (episperm), and edible creamy-white cotyledons[1].
Balkan Range (Western Eastern), Belasitsa Mts, Slavyanka Mts, Pirin Mts, Rhodopi Mts (Wstern); 90 – 850 m alt[2].
Map of general distribution[3]:
The sweet chestnut is a warm-temperate deciduous species, that likes a mean yearly temperature ranging between 8° and 15 °C and monthly mean temperatures over 10 °C during 6 months. The species needs a minimum rainfall that ranges between 600 and 800 mm according to its distribution and interaction with temperatures. The lowest elevations are recommended for the highest latitudes and vice versa1. The chestnut tree displays a high sensitivity to summer droughts issuing from the combination of high temperatures and lack of precipitation. It does not thrive on limestone, preferring well-drained, from very acidic to neutral soils and nutritionally poor sites. This tree can rejuvenate in half-shadow conditions, but needs light for growing from the early pole stage1. It is sensitive to late frost and very adapted to fire-disturbance (vigorous re-sprouter)5. Due to the strong cultivation pressure, it is very difficult to define natural chestnut stands with consociated tree communities. Infact in about 90 % of chestnut forests, this tree is pure or the dominant species. A good example of a natural community might be the Georgian chestnut forests where the species grows with other thermophilous broadleaved deciduous species such as oriental beech (Fagus orientalis), hornbeam (Carpinus betulus syn. Carpinus caucasica), black alder (Alnus glutinosa), field elm (Ulmus minor), Cappadocian maple (Acer cappadocicum syn. Acer laetum), Quercus spp., Caucasian zelkova (Zelkova carpinifolia), red lime (Tilia rubra subsp. caucasica syn. Tilia caucasica) and yew (Taxus baccata)[4].
Due to its multipurpose character, the chestnut tree has always been cultivated in different management systems according to the targeted products and services. Chestnut wood is particularly suitable for external use, thanks to its natural high tannin content that acts as a protection against decay. In former times tannin extraction was also a very common use of the timber. Due to its high re-sprouting capacity, coppice represents the main type of forest management with about 80 % in cover of the chestnut forests, supplying principally fire wood, charcoal, poles (fence, pit-props, etc.), and wood for small products (barrels, shingles, sleepers, etc.). Pure chestnut high forests are rare with a cover of about 10 %, producing timber wood for construction, furniture or long poles. However, high quality uses of chestnut timber are in some cases limited due to the susceptibility of the chestnut to ring-shake. Traditional orchards for fruit production (or groves, as some authors call them), which cover about 20 % of chestnut forests, consist of open stands, usually composed of grafted trees because of the self-sterility of the species. The orchards for staple food consisted of a mix of varieties with different ripening periods. The edible fruits can be consumed in different ways: roasted, candied, boiled, dried, or transformed to flour. Orchards also provided several secondary products such as pasture, hay, mushrooms, berries, etc. In some cases, orchards were also intercropped with cereals. Flowers are rich in pollen and nectar and therefore really appreciated for honey production by bee keepers[5].
[1] Conedera, M., Tinner, W., Krebs, P., de Rigo, D., Caudullo, G., 2016. Castanea sativa in Europe: distribution, habitat, usage and threats. In: San-Miguel-Ayanz, J., de Rigo, D., Caudullo, G., Houston Durrant, T., Mauri, A. (Eds.), European Atlas of Forest Tree Species. Publ. Off. EU, Luxembourg, pp. e0125e0+.
[2] Делипавлов & кол., 2003. Определител на растенията в България. Аграрен университет. Пловдив.
[3] Conedera, M., Tinner, W., Krebs, P., de Rigo, D., Caudullo, G., 2016. Castanea sativa in Europe: distribution, habitat, usage and threats. In: San-Miguel-Ayanz, J., de Rigo, D., Caudullo, G., Houston Durrant, T., Mauri, A. (Eds.), European Atlas of Forest Tree Species. Publ. Off. EU, Luxembourg, pp. e0125e0+.
[4] Conedera, M., Tinner, W., Krebs, P., de Rigo, D., Caudullo, G., 2016. Castanea sativa in Europe: distribution, habitat, usage and threats. In: San-Miguel-Ayanz, J., de Rigo, D., Caudullo, G., Houston Durrant, T., Mauri, A. (Eds.), European Atlas of Forest Tree Species. Publ. Off. EU, Luxembourg, pp. e0125e0+.
[5] Conedera, M., Tinner, W., Krebs, P., de Rigo, D., Caudullo, G., 2016. Castanea sativa in Europe: distribution, habitat, usage and threats. In: San-Miguel-Ayanz, J., de Rigo, D., Caudullo, G., Houston Durrant, T., Mauri, A. (Eds.), European Atlas of Forest Tree Species. Publ. Off. EU, Luxembourg, pp. e0125e0+.
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