EFFECTS OF FOREST CUTTING AND HERBICIDE TREATMENT ON NUTRIENT BUDGETS IN HUBBARD BROOK WATERSHED-ECOSYSTEM
EFFECTS OF FOREST CUTTING AND HERBICIDE TREATMENT ON NUTRIENT BUDGETS IN HUBBARD BROOK WATERSHED-ECOSYSTEM
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DOI：
10.2307/1942440
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发表时间：
1970-01-01
影响因子：
6.1
通讯作者：
PIERCE, RS
中科院分区：
文献类型：
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作者：
LIKENS, GE;BORMANN, FH;PIERCE, RS
1965年11月和12月，哈伯德溪实验林分水岭2上的所有植被被砍伐，定期施用除草剂抑制植被再生两年。年径流量增加了33厘米或39%的第一年和27厘米或28%的第二年以上的预期值，如果流域没有砍伐forest.Large增加，观察到的所有主要离子，除了NH 4+，SO 4 =和HCO 3-，约5个月后，森林砍伐。硝酸盐浓度比未受干扰的条件下的第一年高41倍，第二年高56倍。溪流中的硝酸盐浓度几乎一直超过建议饮用水的健康水平。硫酸盐是溪流中唯一一种在森林砍伐后浓度降低的主要离子。在未受干扰和砍伐森林的情况下，在溪流中的硫酸盐和硝酸盐浓度之间的反比关系。平均河水浓度增加了417%的Ca++，408%的Mg++，1558%的K+和177%的Na+在两年后的森林砍伐。在1967- 1968年期间，流域2的预算净损失（kg/ha-年）为Na 3-N约142，Ca++约90，K+约36，SiO 2-Si约32，Al+约24，Mg++约18，Na+约17，Cl-约4，SO 4-S约0;而对于相邻的未受干扰的流域（W 6），净损失为Ca++9.2，K+1.6，SiO2-Si 17，Al（+）3.1，Mg++2.6，Na+7.0，Cl（-）0.1，SO_4-S为3.3。在未受干扰的生态系统中，降水中硝态氮的输入通常超过排水中的输出，铵态氮同样在未受干扰的生态系统和砍伐森林的生态系统中积累。1966- 1967年，溶解固体的总出口量（不包括有机物）约为75公吨/km（2），1967- 1968年为97公吨/km（2），或约6至8倍以上，将预期为一个未受干扰的分水岭。溶解养分的出口大大增加，从砍伐森林的生态系统是由于氮循环的改变，生态系统。哈伯德溪的支流通常是酸性的，由于森林砍伐，氢离子含量增加了5倍（从pH 5.1到4.3）。森林砍伐后的河水温度在夏季和冬季都高于未受干扰的条件。与未受干扰的溪流中相对恒定的温度相比，砍伐森林后的溪流温度在夏季白天波动3-4摄氏度。砍伐森林后的溪流电导率增加了约6倍，变化更大。砍伐森林导致的溪流浊度增加可以忽略不计，但颗粒物产量增加了约4倍。而颗粒物通常是50%的无机物质，森林砍伐后的初步估计表明，无机物质的比例增加到76%的总particules.Supersaturation的溶解氧从实验流域溪流水是常见的，在所有季节，除了夏季，当流流量低。饱和度取决于水流的流速。硫酸盐、氢离子和硝酸盐是降水的主要成分。据认为，降水中平均硝酸盐浓度的增加相比，从1955年至1956年的数据，以及从1964年至1968年观察到的一致的年度增加，可能是空气污染的普遍增加的一些措施。
All vegetation on Watershed 2 of the Hubbard Brook Experimental Forest was cut during November and December of 1965, and vegetation regrowth was inhibited for two years by periodic application of herbicides. Annual stream-flow was increased 33 cm or 39% the first year and 27 cm or 28% the second year above the values expected if the watershed were not deforested.Large increases in streamwater concentration were observed for all major ions, except NH4+, SO4 = and HCO3-, approximately five months after the deforestation. Nitrate concentrations were 41-fold higher than the undisturbed condition the first year and 56-fold higher the second. The nitrate concentration in stream water has exceeded, almost continuously, the health levels recommended for drinking water. Sulfate was the only major ion in stream water that decreased in concentration after deforestation. An inverse relationship between sulfate and nitrate concentrations in stream water was observed in both undisturbed and deforested situations. Average streamwater concentrations increased by 417% for Ca++, 408% for Mg++, 1558% for K+ and 177% for Na+ during the two years subsequent to deforestation. Budgetary net losses from Watershed 2 in kg/ha-yr were about 142 for Na3-N, 90 for Ca++, 36 for K+, 32 for SiO2-Si, 24 for Al+++, 18 for Mg++, 17 for Na+, 4 for Cl-, and 0 for SO4-S during 1967-68; whereas for an adjacent, undisturbed watershed (W6) net losses were 9.2 for Ca++, 1.6 for K+, 17 for SiO2-Si, 3.1 for A1(+++), 2.6 for Mg++, 7.0 for Na+, 0.1 for C1(-), and 3.3 for SO4-S. Input of nitrate-nitrogen in precipitation normally exceeds the output in drainage water in the undisturbed ecosystems, and ammonium-nitrogen likewise accumulates in both the undisturbed and deforested ecosystems. Total gross export of dissolved solids, exclusive of organic matter, was about 75 metric tons/km(2) in 1966-67, and 97 metric tons/km(2) in 1967-68, or about 6 to 8 times greater than would be expected for an undisturbed watershed.The greatly increased export of dissolved nutrients from the deforested ecosystem was due to an alteration of the nitrogen cycle within the ecosystem.The drainage streams tributary to Hubbard Brook are normally acid, and as a result of deforestation the hydrogen ion content increased by 5-fold (from pH 5.1 to 4.3).Streamwater temperatures after deforestation were higher than the undisturbed condition during both summer and winter. Also in contrast to the relatively constant temperature in the undisturbed streams, streamwater temperature after deforestation fluctuated 3-4 degrees C during the day in summer.Electrical conductivity increased about 6-fold in the stream water after deforestation and was much more variable.Increased streamwater turbidity as a result of the deforestation was negligible, however the particulate matter output was increased about 4-fold. Whereas the particulate matter is normally 50% inorganic materials, after deforestation preliminary estimates indicate that the proportion of inorganic materials increased to 76% of the total particulates.Supersaturation of dissolved oxygen in stream water from the experimental watersheds is common in all seasons except summer when stream discharge is low. The percent saturation is dependent upon flow rate in the streams.Sulfate, hydrogen ion and nitrate are major constituents in the precipitation. It is suggested that the increase in average nitrate concentration in precipitation compared to data from 1955-56,as well as the consistent annual increase observed from 1964 to 1968, may be some measure of a general increase in air pollution.