Reduction of forest floor respiration by fertilization on both carbon dioxide-enriched and reference 17-year-old loblolly pine stands
Reduction of forest floor respiration by fertilization on both carbon dioxide-enriched and reference 17-year-old loblolly pine stands
复制标题
DOI：
10.1046/j.1365-2486.2003.00630.x
复制
发表时间：
2003-06-01
影响因子：
11.6
通讯作者：
Katul, GG
中科院分区：
文献类型：
--
作者：
Butnor, JR;Johnsen, KH;Katul, GG
大气中二氧化碳（CO2 e）的升高会增加森林、草地、农业和湿地系统中的土壤呼吸速率，这是由于生长、根系生物量增加和土壤微生物的生物活性增强。关于森林地面通量如何对CO2浓度升高和营养补充物的综合影响作出反应，人们知之甚少;到目前为止，还没有对大型森林树木进行过实验，甚至没有进行过初步调查。研究了火炬松（Pinus taeda L.）采用FACE技术对种植园进行CO2熏蒸处理，并给予养分补充。原型FACE装置（FACEp; 707 M）于1993年，种植后10年，在中等肥力的网站在杜克森林，北卡罗来纳州，美国，丰富的立场，55帕（CO2 e）。在研究开始时，指定附近的环境CO2（CO 2a）图（117 m（2））作为参考（Ref）。1998年、1999年和2000年春季，将FACEp和Ref小区一分为二，其中一半施尿素，年施用量为11.2gNm2。森林地面呼吸连续监测220天-2000年3月至11月使用两个自动碳排放系统。在FACEp和Ref中对30个位置（每个491 cm（2））进行采样，每个生育力处理中约占一半。林分地面呼吸与5 cm土壤温度呈显著正相关。在测量期间，CO2 e中的Sff速率相对于CO 2a中的Sff速率更大（增加类似于178 g Cm（-2））。在CO 2a和CO2 e图中，施肥导致呼吸速率在统计学上显著下降（下降幅度类似于186 g Cm（-2））。结果表明，在中等肥力的网站封闭冠层森林循环回大气中的同化碳（C）比类似的森林高肥力的网站。我们认识到这项非重复研究的局限性，但其明确的结果为这一重要领域的未来研究提供了强有力的可检验假设。
Elevated atmospheric carbon dioxide (CO2e) increases soil respiration rates in forest, grassland, agricultural and wetland systems as a result of increased growth, root biomass and enhanced biological activity of soil microorganisms. Less is known about how forest floor fluxes respond to the combined effects of elevated CO2 and nutrient amendments; until now no experiments have been in place with large forest trees to allow even preliminary investigations. We investigated changes in forest floor respiration (S-ff) in a Pinus taeda L. plantation fumigated with CO2 by using free-air CO2 enrichment (FACE) technology and given nutrient amendments. The prototype FACE apparatus (FACEp; 707 M) was constructed in 1993, 10 years after planting, on a moderate fertility site in Duke Forest, North Carolina, USA, enriching the stand to 55 Pa (CO2e). A nearby ambient CO2 (CO2a) plot (117 m(2)) was designated at the inception of the study as a reference (Ref). Both FACEp and Ref plot were divided in half and urea fertilizer was applied to one half at an annual rate of 11.2 g N m(-2) in the spring of 1998,1999 and 2000. Forest floor respiration was monitored continuously for 220 days - March through November 2000 by using two Automated Carbon Efflux Systems. Thirty locations (491 cm(2) each) were sampled in both FACEp and Ref, about half in each fertility treatment. Forest floor respiration was strongly correlated with soil temperature at 5 cm. Rates of Sff were greater in CO2e relative to CO2a (an enhancement of similar to178 g C m(-2)) during the measurement period. Application of fertilizer resulted in a statistically significant depression of respiration rates in both the CO2a and CO2e Plots (a reduction of similar to186 g C m(-2)). The results suggest that closed canopy forests on moderate fertility sites cycle back to the atmosphere more assimilated carbon (C) than similar forests on sites of high fertility. We recognize the limitations of this non-replicated study, but its clear results offer strong testable hypotheses for future research in this important area.