湖南耐寒桉树引种研究

THE STUDY ON INTRODUCTION OF COLD TOLERANT EUCALYPTUS IN HUNAN

湖南地处中亚热带,是桉树的适宜引种区,但由于地处内陆和东、南、西三面环山向北敞口的地貌,冬季的低温和夏季的酷暑都比同纬度的其它地区严重,桉树引种的首要目标是获得能适应这种高强度年温差的种类。试验表明,在-7.9℃霜冻条件下,其耐寒力溪谷桉E.badjensis17774>邓恩桉E.dunnii18231>邓恩桉17733>邓恩桉17555>邓恩桉15956>赤桉E.camaldulensis>细叶桉E.tereticomis17430>柳桉E.salogna16620>细叶桉17761>细叶桉16349>巨桉E.grandis18146>巨桉15921>小帽桉E.microcrys13971。在树冠处温度超过44℃的条件下邓恩桉17555、18264、17917,柳桉,边沁桉E bentndmii18787,赤桉34号,山桉E.dalrympleana12563、18692,史密斯桉E.smithii16916无明显灼伤,耐高温。日灼损伤多枝桉E.viminalis14920、18308、19817>溪谷楼19555、19606>史密斯桉19819>山桉16514。15个月生时高生长邓恩桉17555>柳桉>邓恩桉18264>边泌桉18787>史密斯桉19819>溪谷桉19606>邓恩桉17917>多枝桉18308>赤桉34号>史密斯安16916,多枝桉19817>溪谷桉19555>山桉18692>多枝桉14920>山桉16514>山桉12563。邓恩桉,柳桉,赤桉,细叶桉既耐寒又耐高温,能适应湖南的自然条件,而且生长迅速,其中以邓恩桉,柳桉表现最好,赤桉,细叶桉自然分布广,必须进行种源和个体选择。邓恩桉,柳桉,赤桉,细叶桉之所以能适应湖南的自然条件,可能与原产地的气候与引种的气候相似有关,其中最冷月与最热月的气候是否相似是决定因素。湖南应重点从原产地最冷月平均最低温8℃以下,最热月平均最高温度27℃以上,均匀降雨或夏季降雨的地区引种。

Hunan province in warm subtropical is a suitable place for eucalypts introduction. Interior of Hunan is a topographical basin open(min.50 asl)to the north and bordered by mountains to the east.South(to 1050 m asl)and west(to 2000m asl).Its very hot and humid summers along with cold and sometimes freezing winter is severer than those of the same latitude range,which is attributed to such terrain.The primary objective of eucalypts introduction is to get some suitable species which can adapt to such conditions with annual range of temperature varying a lot. Trial results indicated under minus 7.9℃ circumstance.the ability for cold tolerance in order of precedence is E.badjensis17774>E.dunnii18231>E.dunnii17733>E.dunnii17555 >E.dunnii15956>E.camaldulensis>E.tereticornis17430>E.saligna16620>E. tereticornis17761>E.tereticornis16349>E.grandis>E.grandis15921>E.microcrys13971. When the temperature in the tree's crown is beyond 44℃.E.dunnii 17555,18264,17917,E. saligna,E.benthamii 18787,E.camaldulesis34,E.dalrympleana12563,18692,E.smithii16916 have evident damage by sunshine.which displayed good tolerance ability for high temperature.As far as the extent of sunshine damage is concerned,the order from the biggest to the smallest is E.viminalis 14920,18308,19817>E.badjensis 19555,19606>E.smithii 19819>E.dalrympleana16514.out of consideration for height growth in 15 age,e.dunnii 17555 is bigger than e.saligna then,e.dunnii 18264>E.benthamiil8787>E.simithii 19819>E.badjensis 19606>E.dunnii17917>E.viminalis 18308>E.camaldulensis34>E. smithii16916,Eviminalis19817>E.badjensis19555>E.dalrympleana18692>E.viminalis 14920>E.dalrympleana16514>e.dalrympleana12563. E.dunnii,saligna,camaldulensis,tereticornis canendure cold winter and hot summer and well adapted in Hunan.Moreover,they grew very fast.Among them.E.dunnii and E.saligna appearance is the best.E.Camaldulensis and E.tereticornis because of extensive natural distribution need provenance and individual selection. E.dunnii,E.saligna E.camaldulensi and E.terticornis can adapt to Hunan natural condition. which is probably attributed to that the original place's climate is similar to the introduction place's climate. The main determinant of eucalypts introduction success is climate's similarity of cold winter and hot summer between original place and introduction place.We should give priorities to those areas where the monthly mean temperatures in the coldest months and the hottest months are below minus 8℃ and above 27℃ respectively with summer rainfall or umiform rainfall.