为est Ecosystem Science Laboratory
NYSERDA

纽约森林对酸雨阳离子耗竭的敏感性评估

了解美国东北部土壤中钙的矿物来源很重要 因为植物可用的钙已经以加速的速度从土壤中浸出 several decades (Lawrence 等., 1999; Likens 等., 1998) possibly resulting in Ca limitation in some forest ecosystems (Horsley 等., 2000; Huntington, 2005; Long 等., 1997).  And, up to this point, geologically sensitive areas of New York 状态 have been defined as those in which surface waters have been acidified (e.g.4月 等., 1986).   This definition is incomplete in terms of protecting and managing forest health (Nezat 等. 2008).  Areas with few carbonate rocks, such as the Adirondacks 和哈德逊高地，可能确实最容易受到地表水酸化的影响， 土壤的低缓冲能力可以解释死湖现象(Reuss and 约翰逊, 1986).  But the susceptibility of forest soils to Ca depletion may also 取决于微量矿物质如磷灰石的存在和非硅酸盐的遗漏 矿物质作为钙源可能严重高估了对森林健康的威胁 从酸雨中.  磷灰石 is already known as the dominant, P-bearing primary mineral 在土壤中.

对钙耗竭的预测是基于只有盐可交换性的假设 Ca pool is available to plants; the weathering of Ca from parent materials has been 被认为是太慢，在调节空气酸化作用中起不到作用 土壤污染. Because of these assumptions, the role of readily weathered Ca-bearing 微量矿物质，如磷灰石和方解石，一直被忽视的评估 Ca depletion 从酸雨中. Information about the distribution of Ca sources and 树种获得Ca的能力是预测敏感性的关键 导致纽约州森林的钙枯竭，这对可持续发展的影响 forest management and air pollution policy.  

考虑到这些，我们问道:“母材中的含钙矿物有多重要 across New York 状态, and are various tree species able to use this calcium?”

表1.  Sampling locations in the northeastern USA. The bedrock at each site includes bedrock found up to 10 km northward. The surficial deposits are glacial till at all sites 除了布拉舍瀑布(西北)、杰克逊堡和索斯维尔有前冰期 湖沉积.

 

I. Soil source of calcium, and tree responses to same

这项研究首先根据基岩地质和 土壤类型的分布，以及每个站点的土壤采样(图1， 表1).   A new “sequential extraction” procedure was used to quantify the amount 易风化的易交换的、易风化的(如磷灰石)和耐蚀的钙 to weathering (such as silicate minerals).  Leaf litter was also collected from these 测定了不同亲本材料对植物生长的影响 组织化学.  

我们用硝酸提取这些地点的样品来确定是哪种土壤 parent materials in the northeastern USA contained apatite (Figure 2).  我们确定了 这些土壤母质中磷灰石的相似性主要基于它们之间 P:Ca ratio in the extract and that in apatite (3:5) (Figure 2).  有些土壤 源自结晶硅酸盐岩石(奥斯本、斯廷山、萨巴德伊瀑布、 and Lafayettville) had P:Ca>3:5 suggesting the presence of other P sources in addition 以磷灰石.

我们还研究了阿迪朗达克山脉的土壤母质薄片. 我们发现磷灰石是单独的颗粒(图3a)，部分包含在硅酸盐中 矿物(图3b)，或完全包含在硅酸盐矿物中(图3c)。. 磷灰石 grains ranged from 50 to 300 直径毫米.  The concentration of apatite estimated from the extract may be less 因为总比有些磷灰石可能以包裹体的形式出现，而可能完全 armored by, weathering-resistant minerals.

接下来，我们将叶片中的钙浓度与土壤中的钙浓度进行了比较.  白桦、红枫等阔叶林凋落叶中钙含量最高 the 碳酸盐岩的网站 and showed the most response to soil type (Figure 4).  糖枫 平均而言，在非碳酸盐中，凋落叶中的钙含量高于这些物种 sedimentary soils, but increased little as a function of soil Ca.  云杉和冷杉 had low Ca across all sites.  Oak actually had higher Ca in crystalline silicate than 碳酸盐岩的网站. It is not clear from this analysis that any soil horizon or extract is a better predictor of leaf Ca.

由于母材的性质范围，母材的影响 在分析叶面浓度时，应将土壤作为一个连续变量(Ca 可用性(由顺序提取过程定义)在多变量回归中. 按站点类别进行分析是一个良好的开端，并代表了最终产品 获得资助的项目.  Future work will use strontium isotopes and the ratio of calcium 以锶来确定大气中沉积的相对重要性，硅酸盐 不同树种或森林类型的微量矿物质作为钙源.

II. Carbon and Nitrogen storage 在土壤中s

四个额外的地方被评估钙被故意添加在 previous experiments (表2).   Samples were collected at sites where Ca was added 在14到41年前的石灰化实验中，为了确定土壤酸化是否可能 lead to changes 在土壤中 C and N storage.  WE通过比较森林土壤酸化的一个方面来解决土壤酸化的问题 未受干扰的，但受到环境酸性沉积的土壤已处理 with lime to reverse the acidification process.  We found more organic matter and nitrogen 在土壤中s that were not treated.  This comparison suggests that soils may be storing more C and N in organic matter over time as they acidify.

表2.   Description of Liming sites and treatments.

 

3. 研究的结果

我们对纽约州森林土壤中母质的研究表明 that the pool of readily weathered Ca can be substantial; this pool has not traditionally been included in assessment of the Ca available to plants.  在有碳酸盐的地方 或者母材中有磷灰石，钙耗尽的威胁可能没有那么大 如前所述.  It is possible that some tree species or forest types are better than others at accessing nutrients through weathering.  需要更多的研究 以确定在何种程度上森林管理可以用来提高钙的可用性 to forests via weathering of native soil minerals.

IV. 致谢

我们要感谢为我们提供场地的行业合作伙伴:罗伯特·奥布莱恩， Cotton-Hanlon公司.; Roger Dziengaleski 和Dave Osterberg, Finch Pruyn & 公司; Tom 大厅, Pennsylvania Department of Conservation and Natural 资源; and Phil Malerba and Cathy Irwin, International Paper.  Samples were collected by Amber Knowlden, 公园 Byung Bae, Megan Rose Newhouse, Ryan Maher, Jackie Borza, Adrienne Graham，还有 艾米·史密斯.  Chemical analyses were performed under the direction of Joel Blum, University 密歇根.  Carmen Nezat, Byung Bae 公园, Dustin Wood, and Melissa Lucash analyzed data.  Heather Engelman compiled this report.  Additional financial support was provided 由森林工业和美国农业部林业局之间的2020年议程合作 and the National Science Foundation (DEB 0235650 and 0423259).  This work is a contribution 到哈伯德溪生态系统研究，该研究由美国农业部林业局维护 and participates in the NSF Long-Term 生态ogical 研究 program

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