Green J J, Newbery D M
Present address: Land Management Department, Scottish Agricultural College, Craibstone Estate, Aberdeen AB21 9TQ, Scotland, UK.
Institute of Plant Sciences, University of Bern, Altenbergrain 21, CH-3013 Bern, Switzerland.
New Phytol. 2001 Jul;151(1):271-289. doi: 10.1046/j.1469-8137.2001.00156.x.
• Regeneration of the dominant ectomycorrhizal tree Microberlinia bisulcata in groves in Korup, Central Africa, is very poor. The hypothesis was tested that this species is more shade intolerant than other co-occurring species. • In two 1-yr trials, each with M. bisulcata and four other species at a nursery close to Korup, growth was measured under five PAR levels, with ± added P and ± watering in the dry season. In parallel experiments the effects of PAR with two R : FR ratios were investigated. • Increasing PAR had a consistent effect on the rates of increase in plant mass and on changes in the other variables. Doubling soil P, watering and halving the R : FR ratio had almost no effect. However, across species, mass at low PAR and relative growth rate related positively and negatively, respectively, to seed mass. • One contributing factor for the poor recruitment of M. bisulcata is therefore its low survival and slow growth at low PAR, due to its small seed size. The two codominant ectomycorrhizal grove species of Tetraberlinia, with larger seeds, were less affected by low PAR.
• 中非科鲁普地区树林中优势外生菌根树双沟微柏林的更新情况很差。研究人员检验了这样一个假设：该物种比其他共生物种更不耐荫。
• 在两项为期一年的试验中，每项试验都在科鲁普附近的一个苗圃中种植了双沟微柏林和其他四个物种，在五个光合有效辐射（PAR）水平下测量生长情况，并在旱季添加或不添加磷以及浇水或不浇水。在平行实验中，研究了具有两种红光：远红光比例的光合有效辐射的影响。
• 增加光合有效辐射对植物质量增加速率和其他变量的变化具有一致的影响。将土壤磷含量加倍、浇水以及将红光：远红光比例减半几乎没有影响。然而，在所有物种中，低光合有效辐射下的质量与相对生长速率分别与种子质量呈正相关和负相关。
• 因此，双沟微柏林更新情况差的一个促成因素是其种子尺寸小，导致在低光合有效辐射下存活率低且生长缓慢。种子较大的两种优势外生菌根树林物种四沟柏林受低光合有效辐射的影响较小。
