公路建设对木麻黄生长及林下植被物种多样性的影响

 在福建省晋江市，采用样线法垂直晋江沿海大通道西侧布设3条相互平行的样线，对木麻黄Casuarina equisetifolia及其林下植被物种组成和多样性进行调查，并在样线上布设样点调查林内的光照强度、温湿度及土壤容重和土壤含水量，分析沿海公路建设对路域生态因子、木麻黄生长及其林下植被物种多样性的影响。结果表明：①随着距公路距离的增加，光照强度、温湿度、土壤容重和土壤含水量均呈现规律性的变化，距公路100 m处是光照强度从剧烈到缓和的转折点，距公路50 m处是温湿度、土壤容重和土壤含水量从剧烈到缓和的转折点。②栽植于路基附近的木麻黄的生长比未受路基建设干扰的木麻黄差，其中树高、胸径和冠幅在P＜0.01水平差异显著。③随着距公路距离的增加，木麻黄林下植被呈现从喜光植物到耐阴植物的变化，从林下植被以草本为主到灌木草本分布均匀的变化，50~100 m是优势种剧烈变化的范围。④随着距公路距离的增加，木麻黄林下植被的物种多样性总体上呈现逐渐增大并趋于稳定的趋势，其中距公路50~100 m的范围，物种周转速率最高。⑤从沿海大通道对木麻黄人工林林下植被的生物多样性影响的范围看，主要集中在路域100 m的范围之内，随着与公路距离的增加，影响程度降低。图3表3参31

Species diversity in a Casuarina equisetifolia understory along a highway

To analyze changes in roadside ecological factors，in growth of Casuarina equisetifolia，and in understory species diversity with coastal highway construction，three parallel line transects perpendicular to the west side of Jinjiang Coastal Highway and 200 m apart were selected. Light intensity，air temperature，relative humidity，soil bulk density，and soil moisture content were monitored at sample points along the tran-sects. Results indicated that （1） the highway’s zone of influence for light intensity was up to 100 m and for other ecological factors （air temperature，relative humidity，soil bulk density，and soil moisture content） was up to about 50 m. Highway influence decreased as the distance from the highway increased. （2） Tree height，DBH，and crown area of C. equisetifolia were significantly greater （P ＜ 0.01） in undisturbed areas than in roadbed dis-turbance areas. （3） As distance from the highway increased，shade-requiring plants gradually replaced photophilous plants with the herb and plant understory changing to shrubs with a uniform distribution. Dominant species changed most 50-100 m from the highway.（4） As distance from the highway increased，understory species diversity increased gradually and then stabilized with the species turnover rate being maximum at 50-100 m from the highway. （5） The strongest biodiversity influence on the C. equisetifolia trees due to the highway was concentrated in the 0-100 m range with a gradual decrease as the distance from the highway increased.［Ch，3 fig. 3 tab. 31 ref.］