八仙山国家级自然保护区山樱花种群结构特征

Population structure of Cerasus serrulata in Baxianshan National Nature Reserve

山樱花(Cerasus serrulata)是樱花的野生种,其花色和树形优美,是重要而稀少的樱属观赏植物资源。近年,在燕山山脉东麓的天津北部山区,发现比较集中分布的山樱花种群。为明确该野生山樱花种群特征,探究其生态分布习性,本研究选取了天津八仙山国家级自然保护区阴坡、山脊、阳坡3种不同坡位中的山樱花群落,设置样地进行了野外群落学调查,研究了山樱花的种群结构及所在群落物种多样性随海拔和坡位的变化规律,并运用主成分分析法,分析群落间的差异以及群落结构对多样性变化的影响。结果表明:(1)山樱花为落叶阔叶林伴生种,所在群落乔木层主要树种为蒙古栎(Quercus mongolica)、槲栎(Q.aline)、白蜡(Fraxinus chinensis)、鹅耳枥(Carpinus turczaninowii)、臭檀(Euodia daniell)、桑(Morus alba)和元宝槭(Acer truncatum),灌木层主要物种为迎红杜鹃(Rhododendron mucronulatum)、三裂绣线菊(Spiraea trilobata)、小花溲疏(Deutzia parviflora)、大花溲疏(D.grandiflora)、大叶朴(Celtis koraiensis)和锦带花(Weigela florid);山樱花种群结构和所在群落的结构依坡位不同而发生变化;(2)山樱花种群的年龄结构呈倒"J"型分布,600~800 m海拔和阳坡更新状况最好;(3)不同坡位山樱花种群的Shannon生态位宽度为阳坡>山脊>阴坡。与山樱花生态位重叠最高的种群,阴坡为中国黄花柳和蒙古栎,山脊为臭檀和蒙古栎,阳坡为杏和桑;(4)山樱花所在群落的乔木层径级分布呈倒"J"型,多样性指数随海拔增加先增后减;阴坡多样性指数最高,山脊和阳坡较低。灌木层的多样性指数变化趋势与乔木层相反。群落的物种多样性将随群落发育而增加,其优势种的优势度也将进一步提高,作为伴生种的山樱花种群将在阴坡可能衰退,在山脊和阳坡发育良好。该研究可为我国北方地区野生山樱花种群的保护与开发利用提供科学的参考依据。

Cerasus serrulata is a wild species of cherry blossoms,with beautiful flower color and tree shape.It is an important and rare ornamental plant resource of Cerasus.A relatively concentrated population of wild Cerasus serrulata was recently found in the northern mountainous area of Tianjin,which is located at the east of Yanshan Mountains.To clarify the population characteristics of wild Cerasus serrulata and explore its ecological habits,we carried out community investigation at three different slope positions(shady slope,ridge,and sunny slope)in Baxianshan Mountain National Nature Reserve of Tianjin.We examined the population structure and the change of species diversity of Cerasus serrulata community with altitude and slope position.Principal component analysis and redundancy analysis were used to explain the differences among communities and the influence of community structure on diversity.The results showed that:(1)Cerasus serrulata was a companion species in the deciduous broad-leaved forest.The main species of tree layer in the community were Quercus mongolica,Fraxinus chinensis,Quercus aliena,Carpinus turczaninowii,Euodia daniell,Morus alba and Acer truncatum,while the main species of shrub layer were Rhododendron mucronulatum,Spiraea trilobata,Deutzia parviflora,Deutzia grandiflora,Celtis koraiensis and Weigela florid.The population structure and community structure of Cerasus serrulata varied across slope positions.(2)The age structure of Cerasus serrulata population showed an inverted"J"type.The regeneration status was the best in the altitude of 600-800 m and at the sunny slope.(3)Under different slope positions,the Shannon niche breadth of Cerasus serrulata population followed the order of sunny slope>ridge>shady slope.The species with the highest niche overlap with Cerasus serrulata were Salix sinica and Quercus mongolica in shady slope,Euodia deniellii and Quercus mongolica in ridge,and Armeniaca vulgaris and Morus alba in sunny slope.(4)The diameter class distribution of tree layer showed an inverted"J"pattern.The diversity index increased first and then decreased with the increases of altitude.In different slope positions,the diversity index was the highest in shade slope and lower in the ridge and sunny slope.The diversity index of shrub layer was opposite to that of tree layer.The species diversity of the community increased with the development of the community,with the dominance of the dominant species being further increased.The companion species Cerasus serrulata population may decline in the shady slope and develop well in the ridge and sunny slope.Our results can provide a scientific basis for the protection and utilization of wild Cerasus serrulate population in northern China.