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Experiments on the Introduction of Syringa pinnatifolia Hemsl. var. alashanensis and Acer stenolobum Rehd. var. megalophyllum in Mongolia

Volume 2 Number 6 - June 1996

Tong Chengren, Sha Ren, and Ji Meng

Syringa pinnatifolia var. alashanensis (Oleaceae) and Acer stenolobum var. megalophyllum (Aceraceae) are native plants of the Holan Mountains in Inner Mongolia. They have a national protection category of three and a regional (Inner Mongolia) protection category of two.

S. pinnatifolia var. alashanensis is a bush, up to 3 m high with sheet-lobed bark, ovate-orbicular pinnate leaves, with minute hairs on the margin and without a petiole. The flowers are in panicles, bisexual, white and light purple, with 1.5-2 cm capsules, resistant to heat and cold.

The seeds of S. pinnatifolia var. alashanensis can be used as medicine and the plant is used as an ornamental, hardy shrub. The flowers are scented and leaves have an aesthetic value. Plants also conserve the soil covering.

A. stenolobum var. megalophyllum is a small-sized tree, up to 3-4m high. The bark is greyish white and longitudinally fissured. The petiole is up to 6 cm and reddish brown. The leaves are mostly 3-lobed, with the middle lobe longer and the margin minutely serrulated with hairs on the tips. The flowers are in a corymb. The wings of the fruit are obtuse and the fruit becomes ripe during July and August and are resistant to dry and cold weather.

The wood is hard, suitable for making small-sized farm tools. The leaves turn red in autumn and is useful for providing autumn colour.

Both taxa are found in the very dry Xia Zi and neigbouring gullies, in the south of the Holan Mountains, at an altitude of 2,000 m above sea level. The Holan Mountains are located in the Alashan League of the Inner Mongolia Autonomous Region. They extend 200 km from northeast to southwest and are 30 km at their widest part. The climate is cold and dry. The annual average temperature is 7.4-8.5oC, the annual rainfall is 205 mm, with 177-187 frost-free days. There is a small amount of plant cover, which includes xerophilous plants such as Ephedra lepidosperma and Caragana roboroveskyi.

The climate in the Holan Mountains varies greatly, influenced by the steep, high mountains. One side of the mountain has better water conditions and forest soil and there is greater forest cover and trees grow well. There is Pinus tabulaeformis and a belt of Populus davidiana at 2,000- 2,400 m above sea level and Picea crassifolia, Betula platyphylla and a few bushes at 2,000-3,000 m above sea level. High mountain bushes and grassy marshland. occur above 3,000 m. The other side of the lower mountains are mostly barren hills and gullies, naked rocks, serious soil erosion and dry conditions. Here the plant cover is low and only suitable for the growth of xerophilous small sized trees and bushes such as S. pinnatifolia var. alashanensis and A. stenolobum var. megalophyllum. These taxa are vulnerable with only a few remaining in a small area. If the habitat were changed these taxa would possibly die out, therefore improving the management of the area and cultivating them ex situ is very important.

The Inner Mongolia Botanical Garden is in a suburb of Huhhot (40o 90' Lat. 111o41' Long., 1,058m above sea level), which is within the temperate semi-dry continental monsoon belt; the annual average temperature is 6.5oC with an annual average rainfall of 426 mm, mostly limited to July, August and September. This regional climate is suitable for the growth of xerophilous, hardy trees and bushes.

S. pinnatifolia var. alashanensis mainly reproduces by seed. In September, we collected seed from the Holan Mountains and stored them at low temperature for the winter. In April, we soaked the seed for 24 hours with warm water before sowing in the normal way. Our garden introduced seed in 1986 and 1987 and the seedlings grew slowly.

For A. stenolobum var. megalophyllum we developed specific cultivation techniques. After collecting the seed in the autumn, we buried them in wet sand until the following year to give them a low temperature treatment which accelerates germination and is an effective method of breaking dormancy. After collecting seed in 1985, it was sown in 1986. In 1986, the seedlings grew well (up to 20-30 cm after one year). However, the water supply must be controlled in the autumn, to prevent them from growing too fast. This helps them to become woody and helps them to resist the cold in winter.

Our botanic garden is a base for the introduction of trees and bushes into cultivation, especially rare and endangered taxa. In order to conserve the plant resources of our Autonomous region, we must designate the Holan Mountains a protected area and develop methods of cultivation of endangered plants.