Growth and carbon accumulation in root systems of Pinus taeda and Pinus ponderosa seedlings as affected by varying CO(2), temperature and nitrogen.
Growth and carbon accumulation in root systems of Pinus taeda and Pinus ponderosa seedlings as affected by varying CO(2), temperature and nitrogen.
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DOI：
10.1093/treephys/16.7.635
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发表时间：
1996-07
期刊：
影响因子：
4
通讯作者：
J. King;R. B. Thomas;B. Strain
中科院分区：
文献类型：
--
作者：
J. King;R. B. Thomas;B. Strain
据推测，增加大气中的CO（2）浓度增加了碳在细根中的积累，从而改变了土壤碳动态和养分循环。为了评价CO2浓度升高对地下碳氮库的可能影响，对处于演替早期和晚期的火炬松（PinustaedaL.）和美国黄松（Pinus ponderosa Dougl.）分别来自Laws）在杜克大学Phytotron中，在35或70 Pa CO（2）分压、低温或高温（30年每周平均值和30年每周平均值+5 ℃）和1或5 mM NH（4）NO（3）的土壤溶液氮浓度下，从种子生长160天。幼苗收获在每月的时间间隔和生长参数的主根，次生根和主根部分进行评估。黄松根系总生物量对CO（2）浓度的响应为正（增加105%）（P = 0.0001），这是由于CO（2）浓度升高导致所有根系组分的显著增加，但所有其他主效应和交互作用均不显著。火炬松根系总生物量在CO2与温度（P = 0.04）和CO2与氮（P = 0.04）之间存在显著的交互作用。异速生长分析表明，次生根组分的调制是树木改变环境条件的主要反应。在美国黄松中，有一个增加的次生根部分相对于初级和主根部分在低温条件下。低温低氮条件下火炬松碳积累向次生根转移。这两个物种都没有表现出碳积累的变化，以应对CO（2）的升高。我们的结论是，这两个物种都有潜力增加地下生物量显着响应大气CO（2）浓度的上升，这种反应是敏感的温度和氮的火炬松。这两个物种都表现出地下碳积累的小变化，以应对温度和氮的变化，随着时间的推移可能会产生重大的生态系统后果。
It has been hypothesized that increasing atmospheric CO(2) concentration enhances accumulation of carbon in fine roots, thereby altering soil carbon dynamics and nutrient cycling. To evaluate possible changes to belowground pools of carbon and nitrogen in response to elevated CO(2), an early and a late successional species of pine (Pinus taeda L. and Pinus ponderosa Dougl. ex Laws, respectively) were grown from seed for 160 days in a 35 or 70 Pa CO(2) partial pressure at low or high temperature (30-year weekly mean and 30-year weekly mean + 5 degrees C) and a soil solution nitrogen concentration of 1 or 5 mM NH(4)NO(3) at the Duke University Phytotron. Seedlings were harvested at monthly intervals and growth parameters of the primary root, secondary root and tap root fractions evaluated. Total root biomass of P. ponderosa showed a positive CO(2) response (105% increase) (P = 0.0001) as a result of significant increases in all root fractions in the elevated CO(2) treatment, but all other main effects and interactions were insignificant. In P. taeda, there were significant interactions between CO(2) and temperature (P = 0.04) and CO(2) and nitrogen (P = 0.04) for total root biomass. An allometric analysis indicated that modulation of the secondary root fraction was the main response of the trees to altered environmental conditions. In P. ponderosa, there was an increase in the secondary root fraction relative to the primary and tap root fractions under conditions of low temperature. In P. taeda, there was a shift in carbon accumulation to the secondary roots relative to the primary roots under low temperature and low nitrogen. Neither species exhibited shifts in carbon accumulation in response to elevated CO(2). We conclude that both species have the potential to increase belowground biomass substantially in response to rising atmospheric CO(2) concentration, and this response is sensitive to temperature and nitrogen in P. taeda. Both species displayed small shifts in belowground carbon accumulation in response to altered temperature and nitrogen that may have substantial ecosystem consequences over time.