不同坡向人工油松幼林下地表苔藓植物层片的物种多样性与结构特征

Ground bryophyte composition and synusia structures under young Pinus tabuliformis forests along the upper Minjiang River

调查和分析了岷江上游大沟流域的 4个坡向 (偏东坡N -E80°、偏西坡N -W 85°、偏南坡S -E10°、偏北坡N-W2 0°)人工油松 (Pinustabuliformis)林下地表苔藓植物的物种多样性、组成和结构特征。在 4个坡向的油松林下共发现 13种苔藓 ,各林下苔藓物种组成数量在 6 - 13种之间 ,并且具有较高的相似性。冰川青藓 (Brachytheci um glacile)、大羽藓 (Thuidiumcymbifolium)、厚角绢藓 (Entodonconcinnus)、密叶美喙藓 (Eurhynchiumsavatieri)、小酸土藓 (Oxysteguscuspidatus)和光萼苔 (Porellapinnata)为这 4个坡向油松林下的共有种 ,其中冰川青藓、大羽藓为优势物种。 4个坡向人工油松幼林下地表苔藓植物出现频率分别为 10 0 % (偏西、偏北油松林 )和 96 .7% (偏东、偏南油松林 ) ,其平均盖度、平均密度、平均厚度分别在 5 .5 0 %± 0 .90 %至 2 5 .6 6 %± 2 .76 %、4 80 .6 7± 133.6 5至 2 72 4 .80± 4 19.72株 /m2 和 4 .73± 0 .31至 6 .83± 0 .73mm之间。无论是苔藓植物层片的多样性指数还是结构参数 ,均以偏东坡向的油松林下为最低 ;而偏西坡向的油松林下除厚度略低于偏南坡向外 ,其他指标均最高。综合研究结果表明 ,坡向是形成苔藓植物物种多样性组成和结构差异的重要环境因素 。

We investigated ground bryophytes under artificial Pinus tabuliformis forests with four different slope aspects, i.e. NE80°(east facing slope, E), NW85°(west facing slope, W), SE10°(south facing slope, S), and NW20°(north facing slope, N) along the upper reaches of the Minjiang River, in order to explore bryophyte species composition and structural characteristics. Of the 13 bryophyte species occurring in the four artificial forests, only 6, 11, 12 and 7 species occurred in E, W, S , and N forest, respectively. Six moss species, Brachythecium glaciale, Thuidium cymbifolium, Entodon concinnus, Eurhynchium savatieri, Oxystegus cuspidatus, and Porella pinnata existed commonly in all the four forests. The highest frequency for bryophyte occurrence was 100% under W and N forests, and the lowest, under the E and S forests, was 96.7%. According to importance value, the dominant species were Brachythecium glaciale and Thuidium cymbifolium under all four Pinus tabuliformis forests, indicating that they were the most common moss species in the study area. For E, W, S and N forests, ground bryophyte coverage were 5.50%±0.90%, 25.66%±2.76%, 9.03%±1.76% and 7.93%±1.16%, respectively, while shoot density were 480.67±133.65, 2724.80±419.72, 982.00±191.33, 923.47±173.51 shoots/m 2, respectively, and average bryophyte thickness were 4.73±0.31, 6.67±0.41, 6.83± 0.73 , 5.42±0.33 mm, respectively. No statistical differences(P>0.05) in structural parameter were found among E, S and N forests. By comprehensive analysis, it was found that W forest was the best of the four forests in bryophyte composition and synusia structures, indicating that slope aspect is one important environmental factor inducing differences of ground bryophyte composition and synusia structure, and indirectly affecting the survivorship and growth of bryophytes.