Intraspecific diversity: adaptive differentiation of Picea mongolica W. D. Xu ecotypes

Picea mongolica W. D. Xu is an endemic and endangered species which is only found in semi-arid areas of northern China. It has been widely used as an afforestation tree in the establishment of the Three-North Shelterbelt System for its adaptation to arid soils and as a virescent tree in urban gardens and streets for its beautiful shape. Due to different microenvironments, P. mongolica populations may differentiate into many ecological groups with different adaptive abilities. Long-term adaptation to a dry environment makes P. mongolica differentiate into different ecotypes. Typical ecotypes are P. mongolica f. purpurea （Fp）, P. mongolica f. rubra （Fr） and P. mongolica f. viridis （Fv）. Our results show that cone size is clearly not uniform among different ecotypes; the largest cones are found in the Fv ecotype and the smallest in Fp. There were also distinct differences between these ecotypes in terms of height and length of squama. At the molecular level, the zymograms of peroxidase and lipase prove the existence of different ecotypes in P. mongolica. The results are useful for investigating and managing this rare spruce species in China.

An environmental gradient change of Picea mongolica seedling from the center of a forest canopy gap in forest-steppe ecotone in Inner Mongolia Autonomous Region of China

In sandy forest with a forest canopy gap for a period of over 30 years, the spruce（Picea mongolica） seedlings were monitored on two 5-m- wide transects from the center of a large gap into the surrounding forest. The farther they were to the far center, the taller grew the seedling and the more is the number of seedling. There were many seedlings under the canopy but almost all seedlings died before they grow up. Along the forest edge, growth of seedlings was temporarily enhanced by lateral penetration of light from the gap. The implications for natural forest regeneration dynamics are discussed. Our results prove that in P mongolica forest a gap disturbance creates a non-uniform environment for regeneration of the species, and determines that the forest was a non-even aged forest.

An overview of the “Three-North” Shelterbelt project in China

The ＂Three-North＂ Shelterbelt is the largest and most distinctive artificial ecological engineering project in China. It has been conducted since November 25, 1978 in the ＂Three-North＂ （i.e., Northeast China, North China and Northwest China） regions. In this study, the background and the essential benefits of the ＂Three-North＂ Shelterbelt project are summarized. The basic status and future development of the ＂Three-North＂ Shelterbelt project are also studied. As well, we tried to discuss the problems existing in the current shelterbelt system and the strategies to conduct this ecological project rationally.

动态地植物学说的理论与实践

刘慎谔先生是中国著名的植物学家、生态学家和林学家,他在20世纪60年代初提出了动态地植物学理论。本文作者利用动态地植物学理论,研究了中国东北地区植被的几个焦点问题:(1)地带性顶极是动态地植物学核心问题,在一个地区只有一个地带性顶极,受大气候控制,其余的都是由局部环境条件影响下形成的非地性顶极。东北地区从东南向西北随着水分条件的变化出现湿润区、半湿润区和半干旱区,地带性顶极相应出现森林、森林草原和典型草原等地带性顶极植被类型。从南向北随着热量变化出现暖温性赤松(Pinus densiflora)-栎树(Quercus spp.)混交林、暖温性油松(Pinus tabuliformis)-栎树混交林、温性沙松(Abies holophylla)-红松(Pinus koraiensis)阔叶混交林、温性红松阔叶混交林和寒温性明亮针叶林等地带性顶极植被类型。除研究水平地带性顶极外,我们还研究了垂直地带性顶极或气候层顶极、前顶极和后顶极及其相互转化关系。(2)根据动态地植学中的极地苔原迁移路线,徐文铎发现了中国第2块苔原植被—大兴安岭亚高山苔原,进而澄清了在中国生态学和自然地理学领域中的山地苔原(mountain tundra)和山地冻原(mountain crymic)的基本概念和本质上的区别,发现东北山地苔原只起源于欧亚大陆北极苔原,是欧亚大陆极地苔原植物区系组成的一部分。(3)动态地植物学强调植物种的演变生态过程和物种正确鉴定的重要性。在生态环境非常脆弱的浑善克沙地发现了沙地云杉(Picea mongolica)新树种,由沙地云杉为建群种形成了超地带性顶极(post zonal climax),是陆地上非常特殊的森林生态系统类型。为系统研究沙地云杉生态系统组成、结构和功能,开展了沙地云杉生态环境、种的起源、分子生态、个体生态、种群生态、群落生态、生态系统生态、保护生态等基础研究。(4)动态地植物学说认为:大气候在不断变化,植被对全球气候变化反应敏感。植被与气候的关系是辩证统一的,有什么样的气候就应该有什么样的顶极植被,且在一个气候区内只能有一个地带性顶极植被。全球气候变暖给动态地植物学研究增加了新的内容,开拓了新的研究领域。地带性顶极植被受大气候控制,且是最敏感、最有代表性的植被类型。若未来气温升高2℃,则东北地区森林地带性顶极,除植被组成、结构和功能发生变化外,其分布格局变化较大,将向北迁移约443~708 km。草原地带性顶极向东迁移926 km。(5)植被区划是动态地植物学在生态建设中的应用。植被区划应该建立在植被地带性基础上,且要反映历史情况与过去的气候关系。高级区应以地带性顶极为主,低级区可以考虑非地性顶极植被类型。因此,植被区划是动态地植物学中最结合生产实践和永续利用自然资源的科学依据。我们根据动态地植物学中植被区划的原则、依据、指标和系统,开展了黑龙江省植被区划、中国东北植被区划和中国东北植被生态区划等研究。