东北地区蒙古栎群落区系地理成分分析

分析了东北地区蒙古栎群落１９２ 个属分布区类型，其中温带分布属占７２ ％ ， 热带分布属占９ ．７ ％ ．也比较了东北地区１０ 个地点和河北省１ 个地点的蒙古栎群落物种所在属的分布区类型， 统计了不同地点属的分布区类型占总属的比例，计算了温带属与热带属（ Ｔ／ Ｒ） 的比值，结果发现蒙古栎群落的温带分布属和Ｔ／Ｒ 值（ 温带属和热带属之比值） 不仅受纬度地带性影响，也受垂直地带性影响；在海拔相差不大的情况下蒙古栎群落Ｔ／Ｒ 值随着纬度的递增而递增，热带分布属随着纬度递增而减少．垂直地带性对Ｔ／ Ｒ 之比率也有较大的影响，使得Ｔ／Ｒ 值随纬度变化时出现波动．并给出了Ｔ／Ｒ 值、纬度和海拔三者关系的回归方程，结果表明Ｔ／ Ｒ 值与纬度、海拔有着比较精确的数量关系．最后对这种分布格局产生的原因进行了解释

Analysis on phytogeographical elements of Quercus mongolica community in northeast China

The distribution types of 192 genera of Quercus mongolica community in 10 sites of northeast China and one site of Hebei Province were analyzed, and the proportion of each type to the total as well as the ratio of temperate genera to tropical genera (T/R ratio) in each site were calculated. Among the distribution types in northeast China, those of the temperate and tropical genera accounted for 72.0% and 9.7%, respectively. The latitude and altitude could affect the genera distributed in temperate zone and their T/R ratio. The T/R ratio increased with increasing latitude, while the number of tropical genera decreased if the altitudes were the same or similar. Altitude could affect T/R ratio more obviously, causing its fluctuation with latitude. The regression equation of T/R ratio with latitude and altitude was given, and the reasons producing this distribution pattern were also explained.