Long-Term Dynamics of Coarse Particulate Organic Matter in Three Appalachian Mountain Streams
Long-Term Dynamics of Coarse Particulate Organic Matter in Three Appalachian Mountain Streams
复制标题
阿巴拉契亚山脉三条溪流中粗颗粒有机物的长期动态
DOI：
--
复制
发表时间：
1995
影响因子：
--
通讯作者：
K. Chung
中科院分区：
文献类型：
--
作者：
J. B. Wallace;M. Whiles;S. Eggert;T. Cuffney;G. J. Lugthart;K. Chung
北卡罗来纳州 Coweeta 水文实验室在 8（一条河流）至 9.5 年（两条河流）期间对三条源头水流的粗颗粒有机物 (CPOM) 输出进行了连续研究。年间 CPOM 出口量的差异为 9.2 至 > 16 倍，远大于年径流量 3.5 至 5.0 倍的差异。年出口量与年流量的相关性较差，更多的是风暴频率和强度的一个因素。超过 63% 至 >77% 的 CPOM 出口发生在最大的 20 场风暴期间。对于整个研究中的所有河流，各个采样间隔期间的出口与该间隔期间的最大流量密切相关（r2 0.43-0.54，p<0.001）。所有溪流的叶片总出口量和每单位最大流量的叶片出口量在秋季最大，在春季和夏季最低。三个溪流中的两条溪流中，木质碎片的出口比树叶的季节性变化更大。尽管异源 CPOM 是这些溪流有机物输入的最大来源 (>86%)，但 CPOM 仅占有机物输出总量的 1.8-3.8%，这表明 CPOM 在这些小而高梯度的溪流中保留很高。大多数出口以细颗粒有机物 (FPOM) 和溶解有机物 (DOM) 或呼吸二氧化碳的形式出现。通过标记的人造“叶子”和“棍子”的运动进一步说明了水流保持性，其中“叶子”的最大下游运动为 42 m/年，“棍子”的最大下游运动为 10 m/年。令人惊讶的是，木质碎片的出口占投入的百分比最大。这可能是由于低估了木质凋落物的输入量和木质残骸的分解速度较慢，从而导致了更多的未收作物和在暴风雨期间有更多的木质残骸可供运输。在八年的研究中的三年中，一条溪流（C 54）接受了杀虫剂的季节性处理，大大减少了无脊椎动物的数量。与未经处理的溪流相比，经过三年的处理后，观察到落叶植物的大量增加。然而，与未经处理的水流相比，经过处理的水流的 CPOM 输出并没有显着增加。在处理过程中，输出的颗粒有机物的 CPOM:FPOM 比率是未处理流的两倍以上，或者在未处理流时为 C 54 的两倍以上。这一增长主要是由于 FPOM 出口大幅减少，而不是 CPOM 出口大幅增加。尽管 1989 年和 1990 年期间，暴风雨从所有河流的湿润周边清除了大量的 CPOM，但大部分清除的物质仍保留在狭窄的河岸区内，并且没有输出到下游河段。这些高梯度溪流中湿润周边和邻近河岸带之间 CPOM 的移动和交换与流经具有广阔洪泛区的低地地区的溪流有相似之处。
Export of coarse particulate organic matter (CPOM) from three headwater streams was studied continuously over a period of 8 (one stream) to 9.5 years (two streams) at the Coweeta Hydrologic Laboratory, North Carolina. Annual CPOM export among years varied by factors of 9.2 to > 16 ×, much greater than the 3.5 to 5.0 × variation in annual stream discharge. Annual export was poorly correlated with annual discharge and was more a factor of storm frequency and magnitude. Over 63 to >77% of all CPOM export occurred during the largest 20 storms. Export during individual sampling intervals was strongly related to maximum discharge during the interval (r2 0.43-0.54, p<0.001) for all streams throughout the study. Total leaf export and leaf export per unit maximum discharge were greatest during the autumn and lowest during the spring and summer months in all streams. Export of woody debris was more seasonally variable than that of leaves in two of the three streams. Although allochthonous CPOM is the greatest source of organic matter inputs to these streams (>86%), CPOM represented only 1.8-3.8% of total organic matter export, indicating that CPOM retention is high in these small, high-gradient streams. Most export occurs in the form of fine particulate organic matter (FPOM) and dissolved organic matter (DOM), or respired CO2. Stream retentiveness was further illustrated by movement of marked artificial "leaves" and "sticks", which displayed maximum downstream movement of ∼42 m/yr for "leaves" and 10 m/yr for "sticks". Surprisingly, export as a percent of inputs was greatest for woody debris. This is probably attributable to both underestimates of woody litter inputs and slower decomposition rates for woody debris, resulting in greater standing crops and availability of woody debris for transport during storms. For three of the eight years of study, one stream (C 54) received seasonal treatments with an insecticide that drastically reduced invertebrate populations. Large increases in leaf litter standing crop were observed following three years of treatment compared with untreated streams. However, CPOM export from the treated stream did not increase significantly compared with untreated streams. During treatment the CPOM:FPOM ratio of exported particulate organic matter was over twice that of untreated streams, or C 54 during periods when the stream was not treated. This increase was primarily a result of massive reduction in FPOM export, rather than large increases in CPOM export. Although storms removed large amounts of CPOM from the wetted perimeter of all streams during 1989 and 1990, most removed material was retained within the narrow riparian zone, and not exported to downstream reaches. Movement and exchange of CPOM between the wetted perimeter and adjacent riparian zones in these high-gradient streams demonstrates similarities with streams draining lowland regions with extensive floodplains.