浙江宁波天童山国家森林公园表土花粉初步分析

PRELIMINARY POLLEN ANALYSIS OF SURFACE SAMPLES FROM THE TIANTONGSHAN NATIONAL FOREST PARK IN NINGBO,ZHEJIANG PROVINCE,EAST CHINA

浙江宁波天童山国家森林公园小区域植被表土花粉分析表明:花粉植物群以栲属/柯属(Castanopsis/Litho-carpus)占优势,常见有木荷属(Schi ma)、青冈属(Cyclobalanopsis)、杨梅属(Myrica)、冬青属(Ilex)、木犀科(Oleaceae)、山茶科(Theaceae)等常绿阔叶树种,并伴生有栎属(Quercus)、枫香属(Liquidambar)、鹅耳枥属(Carpi-nus)、盐肤木属(Rhus)等落叶阔叶类型,基本反映了中亚热带北缘现生常绿阔叶林植被面貌和特征。花粉组合随海拔高度的变化主要与微地形生境、人类活动干扰等因素有关,并非指示植被及气候的垂直分异。孢粉组合中高含量的松属(Pinus)、丰富的蕨类植物及较高的炭屑浓度与当地伐木取薪等人类活动密切相关。天童山表土花粉资料为理解研究区现生植被分布格局、生态恢复和探讨地质历史时期区域植被变化、环境演变及人类活动提供了现实材料和依据。

Palynological analysis of a total of ten surface samples from the Tiantongshan National Forest Park reveals that the pollen flora is dominated by diverse broadleaved evergreens mainly represented by Castanopsis/Lithocarpus,Schima,Cyclobalanopsis,Myrica,Oleaceae,Ilex,Eurya and Camellia,etc.,generally corresponding to the mo-dern Mid-subtropical （i.e. warm temperate） broadleaved evergreen forest,the climatic zonal vegetation developed under the Asian monsoonal climate in East China. Deciduous broadleaved taxa stay at moderate level and increase markedly in the upper part of the mountain such as Quercus,Liquidambar,Platycarya,Carpinus and Rhus. In addition,herbs are limited whereas fern spores are abundant. Based on variation of main arboreal taxa,four pollen zones are recognized along the elevation gradient of the mountain as follows：Zone 1 of Pinus-Castanopsis/Lithocarpus-Hicriopteris/Dicranopteris assemblage （145 m a.s.l.） has a high percentage of Pinus in association with abundant Hicriopteris/Dicranopteris,which points to the strong human activities in low hills. Zone 2 （c.149—250m a.s.l.） is characterized by the dominance of Castanopsis/Lithocarpus,along with Schima,Oleaceae,Cyclobalanopsis,Eurya,Myrica,Ilex,Daphniphyllum and Camellia,suggesting the zonal evergreen broadleaved forest vegetation. In Zone 3 （c.250—360 m a.s.l.）,Castanopsis/Lithocarpus-dominated forest gives way to diverse evergreens indicated by the significant rise of Cyclobalanopsis,Schima,Myrica and Daphniphyllum,primarily attributing to the relatively high topography and species competition. Zone 4 （c. 400—560 a.s.l.） differs from Zone 3 by the rapid increase of Quercus-dominated broadleaved deciduous woods and terrestrial herbs such as Poaceae,Artemisia and Asteraceae. The specific niche,i.e. strong wind,poor soil and steep topography in high altitude,limits the distribution of evergreens and favors the expansion of deciduous forest and grassland in an open patch.