Temporal responses of community fine root populations to long-term elevated atmospheric CO2 and soil nutrient patches in model tropical ecosystems
Temporal responses of community fine root populations to long-term elevated atmospheric CO2 and soil nutrient patches in model tropical ecosystems
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DOI：
10.1016/s1146-609x(97)80027-6
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发表时间：
1997-01-01
影响因子：
1.8
通讯作者：
Arnone, JA
中科院分区：
文献类型：
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作者：
Arnone, JA
C-3植物的生物量和细根长度密度以及根系生长的干物质总体分配在CO2升高的情况下有所增加。然而，CO2浓度升高对植物群落细根种群大小的刺激作用是否会持续存在，或者高CO2浓度下的细根种群是否比环境CO2条件下的细根种群更快（或可能更晚）达到最大值，目前尚不确定。二氧化碳浓度升高下林分水平养分需求的增加是否会通过促进细根向相对营养丰富的土壤微点增殖而导致更强烈的养分觅食，目前还不清楚。我在一个530天的实验中解决了这些问题，在四个等效的生态系统（17米(3)）中建立了模型热带植物群落，其中植物共享一个共同的低肥力土壤。在实验的前半期，维持在高CO2水平（610亩/升（-1））的生态系统中的细根（小于或等于2毫米空集）种群（生物量和长度密度）比维持在环境CO2水平（340亩/升（-1））的生态系统中的细根种群（生物量和长度密度）增长得更快，并且在整个实验过程中也保持更高。数据还表明：(1)两种CO2水平下的细根种群最终趋于稳定；(2)CO2浓度升高（占用土壤体积）下的稳定发生得更快；(3)CO2浓度升高下的稳态种群可能略大于环境CO2下的稳态种群。在所有生态系统中，细根在人工营养化土壤中的增殖都非常显著（比在非营养化土壤中的增殖高22% ~ 75%）。然而，升高的CO2并没有促进向富集微位点的增殖。因此，即使在低肥力土壤中，二氧化碳浓度升高也可能不会增加对营养丰富的微位点的利用，这表明二氧化碳浓度升高也不太可能增加植物的养分捕获。
Biomass and length density of fine roots, as well as overall allocation of dry matter to root growth, of C-3 plants has been shown to increase under elevated CO2. However, it is uncertain whether the stimulatory effect of elevated CO2 on fine root population size in plant communities will persist, or whether fine root populations at high CO2 simply reach their maximum sooner (or possibly later) than those produced under ambient CO2. It is also unclear whether increased nutrient demand at the stand-level under elevated CO2 will lead to more intense nutrient foraging via enhanced fine root proliferation into relatively nutrient-rich soil microsites. I addressed these questions in a 530 day experiment with model tropical plant communities established in four equivalent ecosystem (17 m(3)) in which plants shared a common low fertility soil. Fine root (less than or equal to 2 mm empty set) populations (biomass and length density) in ecosystems maintained at elevated CO2 (610 mu l l(-1)) increased more rapidly than those in ecosystems maintained at ambient CO2 (340 mu l l(-1)) during the first half of the experiment and also remained greater over the entire experiment. The data also indicate that: (1) fine root populations at both CO2 levels eventually stabilize, (2) stabilization occurs sooner under elevated CO2 (occupation of the soil volume), and (3) steady-state populations under elevated CO2 may be slightly larger than those maintained under ambient CO2. Fine root proliferation into artifically nutrient-enriched microsites was dramatic in all ecosystems (22% to 75% greater than into non-enriched soil). However, proliferation into enriched microsites was not enhanced by elevated CO2. Thus, elevated CO2 may not enhance exploitation of nutrient-rich microsites even in low fertility soils, suggesting that increased plant nutrient capture under elevated CO2 also may be unlikely.