Soil moisture, water tension, and water table relationships in a managed cutover bog
Soil moisture, water tension, and water table relationships in a managed cutover bog
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DOI：
10.1016/s0022-1694(97)00037-1
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发表时间：
1997-12
影响因子：
6.4
通讯作者：
J. Price
中科院分区：
文献类型：
--
作者：
J. Price
本研究评估了一个收获沼泽的水文条件，在那里实施了各种水管理方案来改善限制泥鳅再生的条件。研究地点包括一个天然的沼泽（天然的），一个最近排水和收获的沼泽（排水的），这提供了极端的水文。还包括一个排水的收获沼泽，沟渠被(1)没有其他管理（阻塞），(2)泥炭以开放水域为界，间隔5米（5米），(3)表面有秸秆覆盖（覆盖物）。1995年5月至9月的研究期间比正常情况更干燥。8月下旬，排水区地下水位降至- 107 cm，而阻塞区地下水位降至- 72.5 cm。5米和覆盖地（沟渠也被堵塞）的地下水位下降与自然地相似（最小约为0.45 m）。−62厘米)。在排水和阻塞的样地，7月初以后地下水位变化不大，表明与大气的水交换只发生在非饱和带之间。尽管地下水位深度差异很大，但排水和封堵场地上3cm土层的土壤水分基本相同，均降至20%以下，而覆盖时最低为30%。土壤水张力曲线表明，这种储存变化主要发生在30 cm以上。因此，地下水位深度并不是地表可用水量的良好指标。在排水和阻塞区域，非饱和区（地表以下1cm）的压头分别在18%和34%的时间保持在0和- 100 cm （mb）之间，而在开放水域（5 m）和覆盖的水管理下，压头分别增加到55%和97%。然而，最大的张力出现在阻塞部位（- 355 cm），而不是排水部位（- 247 cm），表明前者对Sphagnum的适宜性较低。这是由于堵塞部位的体积密度更高（因此孔隙结构更小）（ρb=92.1 kg，而55.7 kg m−3）。阻塞部位的堆积密度较高是由于受到干扰的时间较长。这意味着恢复应该在收获完成后尽快开始。
This study evaluates the hydrological conditions in a harvested bog where various water management schemes have been implemented to ameliorate conditions limiting Sphagnum regeneration. The study sites included a natural bog (natural), a recently drained and harvested bog (drained), which provided the hydrological extremes. Also included are a drained harvested bog with ditches blocked with (1) no other management (blocked), (2) peat bounded by open water at 5-m intervals (5-m), and (3) with straw mulch on the surface (mulch). The study period from May to September 1995 was drier than normal. The water table in the drained site descended to −107 cm by late August, compared with −72.5 cm at the blocked site. Both the 5-m and mulch sites (ditches also blocked) had water table recessions similar to the natural site (minimum approx. −62 cm). In the drained and blocked sites, little variation in water table depth occurred after early July, suggesting water exchanges with the atmosphere occurred to and from the unsaturated zone only. Soil moisture in the upper 3 cm layer on the drained and blocked site were similar, in spite of greatly different water table depths, dropping below 20% by volume, compared with a minimum of 30% when mulch was used. Soil water tension profiles suggest most of this storage change occurred in the upper 30 cm. The water table depth, therefore, was not a good indicator of water availability at the surface. Pressure head in the unsaturated zone (1 cm below the surface) in the drained and blocked sites was maintained between 0 and −100 cm (mb) 18 and 34% of the time, respectively, and with water management with open water (5-m) and mulch, increased to 55 and 97% of the time, respectively. The greatest tension, however, was observed on the blocked site (−355 cm), rather than the drained site (−247 cm), suggesting lower suitability for Sphagnum at the former. This was attributed to the higher bulk density (hence smaller pore structure) at the blocked site (ρb=92.1 kg compared with 55.7 kg m−3). Higher bulk density at the blocked site was ascribed to its longer time since disturbance. This implies restoration should begin as soon as possible after harvesting is finished.