濒危植物矮牡丹致濒原因分析

The endangered causes of Paeonia suffruticosa var. spontanea, an endemic to China

矮牡丹是我国特有种 ,为国家 3级濒危保护植物 ,仅分布于山西南部 (稷山和永济 )和陕西中北部 (华山、铜川和延安 )。矮牡丹分布区的生态环境特征是 :热量条件较好 ,降水量较少 ,立地条件较差。在落叶阔叶林和落叶阔叶灌丛中 ,矮牡丹往往多为伴生成分 ,偶尔可成为灌木层的优势种。矮牡丹濒危的主要原因有 :( 1 )开花和结实率较低 ,产生的种子较少 ;( 2 )种子的特殊休眠特性导致萌发率较低 ;( 3)生长发育缓慢 ;( 4 )竞争能力较弱和 ( 5 )人为干扰严重。此外 ,针对矮牡丹的濒危现状和原因 ,还提出了科学保护对策。

Paeonia suffruticosa var. spontanea is an endemic to China, being one of the state-protected third-grade threatened plants. It distributes only in Majiagou, Jishan belonged to the tip of Luliang Ranges, Shuiyukou, Yongji belonged to the western of Zhongtiao Ranges in Shanxi and Huashan Mountains, Huanglong Mountain, Tongchuan and Wanhua Mountain, Yan'an in Shaanxi, respectively. The distribution region is located in 109°05′～110°57′E , 34°29′～35°05′ N, and above sea level from 1000m to 1800m. The zonal vegetations of the distribution area of P. suffruticosa var. spontanea in China consist of deciduous broad-leaved forests that main vegetation types are Quercus variabills forest, Q. baronii forest, Q. liaotungensis forest, Q. aliena var. acuteserrata forests, Carpinus turczaninowii forest, and Acer spp. and Tillia mongolica forest. Because of human being disturbances, primary vegetations were replaced by second vegetation that were Rosa xanthina shrub, Vitex negundo var. heterophylla shrub, Forsythia suspensa shrub, Spiraea trilobata shrub, Ostryopsis davidiana shrub, Sophora viciifolia shrub, Ziziphus jujuba var. spinosa shrub, Bothriochola ischaemum community and Artemisia spp. community, respectively. P. suffruticosa var. spontanea exists frequently in the shrub layer of Q. baronii forest, Q. liaotungensis forest, and Acer spp. and Tillia mongolica forest as one of the accompanying species, and in the shrub layer of Syringa pekinensis shrub as one of the dominant species occasionally. The ecological characteristics of P. suffruticosa var. spontanea areas are as follows: heat energy was efficiency, which ≥10℃ annual accumulated temperatures were more than 3200℃ except for Huashan Mountains. Annual rainfall was from 483 mm to 704 mm. The stands are poor that the soil layer is thinner, the slope from 20° to 70° and the nutrition is poorer. The threatened reasons for P. suffruticosa var. spontanea were involved with: (1) The flowering and producing seeds were a fewer. The average flowering number was 0.47/(per stem·a), the average follicle was 0.67/(per stem·a) and the average seed produced is 0.91/(per stem·a), respectively. (2) The special dormancy characteristics of the seeds resulted in its lower germination ratio. The germination temperature was restricted from 10~15℃, and the germination ratio was about 30%. Moreover, it has special dormancy feature that needed harsh lower temperature to break its dormancy otherwise its seed was not almost germinated. (3) The growth and development rate were lower. The growth was 9.14 cm/a for height and 0.55 cm/a for stem in Wanhua Mountain, Yan'an. The biomass were 0.3260 t/hm 2 in Majiagou, Jishan and 0.0296 t/hm 2 in Shuiyukou, Yongji, respectively, which were lower than that of R. xanthina, 4.175 t/hm 2, O. davidiana 4.68 t/hm 2 and S. pubescens 1.225 t/hm 2, however, the habitat of R. xanthina, O. davidiana and S. pubescens was very similar to that of P. suffruticosa var. spontanea. Because the growth of P. suffruticosa var. spontanea was so slowly, its competition ability was less than that of the other shrubs, such as S. pubescens, Coteneaster zabelii and C. acutifolius et al. (4) The intervention of human activities was severity, in which one of the main factors was to collect the root of P. suffruticosa var. spontanea as one of the Chinese traditional medicines from 1950's to 1970's. Furthermore, the strategies for protection P. suffruticosa var. spontanea are discussed, including that it is free from the disturbance of human being, the nature reserve for P. suffruticosa var. spontanea should be established urgently in Majiagou, Jishan and Shuiyukou, Yongji, Shanxi and Wanhua Mountain, Shaanxi, and the protection measure of off-site for it should be carried out as soon as possible.