King John S, Albaugh Timothy J, Allen H Lee, Buford Marilyn, Strain Boyd R, Dougherty Phillip
School of Forestry and Wood Products, Michigan Technological University, Houghton, MI 49931, USA.
Forest Nutrition Cooperative, North Carolina State University, Raleigh, NC 27695, USA.
New Phytol. 2002 May;154(2):389-398. doi: 10.1046/j.1469-8137.2002.00393.x.
• Availability of growth limiting resources may alter root dynamics in forest ecosystems, possibly affecting the land-atmosphere exchange of carbon. This was evaluated for a commercially important southern timber species by installing a factorial experiment of fertilization and irrigation treatments in an 8-yr-old loblolly pine (Pinus taeda) plantation. • After 3 yr of growth, production and turnover of fine, coarse and mycorrhizal root length was observed using minirhizotrons, and compared with stem growth and foliage development. • Fertilization increased net production of fine roots and mycorrhizal roots, but did not affect coarse roots. Fine roots had average lifespans of 166 d, coarse roots 294 d and mycorrhizal roots 507 d. Foliage growth rate peaked in late spring and declined over the remainder of the growing season, whereas fine roots experienced multiple growth flushes in the spring, summer and fall. • We conclude that increased nutrient availability might increase carbon input to soils through enhanced fine root turnover. However, this will depend on the extent to which mycorrhizal root formation is affected, as these mycorrhizal roots have much longer average lifespans than fine and coarse roots.
• 生长限制资源的可利用性可能会改变森林生态系统中的根系动态，进而可能影响陆地与大气之间的碳交换。通过在一片8年生的火炬松（Pinus taeda）人工林中设置施肥和灌溉处理的析因试验，对一种具有商业重要性的南方木材树种进行了评估。
• 经过3年的生长，使用微根管观察了细根、粗根和菌根根长的生产与周转情况，并与茎生长和叶片发育进行了比较。
• 施肥增加了细根和菌根的净生产量，但对粗根没有影响。细根的平均寿命为166天，粗根为294天，菌根为507天。叶片生长速率在春末达到峰值，并在生长季节的剩余时间里下降，而细根在春季、夏季和秋季经历了多次生长高峰。
• 我们得出结论，养分可利用性的增加可能会通过增强细根周转来增加土壤中的碳输入。然而，这将取决于菌根形成受影响的程度，因为这些菌根的平均寿命比细根和粗根长得多。
