Enhanced Transpiration by Riparian Buffer Trees in Response to Advection in a Humid Temperate Agricultural Landscape
Enhanced Transpiration by Riparian Buffer Trees in Response to Advection in a Humid Temperate Agricultural Landscape
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DOI：
10.1016/j.foreco.2011.01.027
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发表时间：
2011-04
影响因子：
3.7
通讯作者：
V. Hernandez-Santana;H. Asbjornsen;T. Sauer;T. Isenhart;K. Schilling;R. Schultz
中科院分区：
文献类型：
--
作者：
V. Hernandez-Santana;H. Asbjornsen;T. Sauer;T. Isenhart;K. Schilling;R. Schultz
河岸缓冲被设计为一种管理措施，以增加入渗，减少地表径流，以及从农田到邻近溪流的沉积物和非点源污染物的运输。实现这些生态系统服务目标在一定程度上取决于它们通过蒸腾作用从土壤中除去水分的能力。在这些系统中，缓冲系统的农田和树木之间的边缘可以产生平流过程，这可能会影响树木的用水。我们在美国中西部（爱荷华州）玉米带地区于1994年建立的湿润温带气候下的河岸缓冲系统进行了实地研究。目的是估算河岸缓冲林的林分蒸腾，量化缓冲林系统对水分利用的控制，确定缓冲林系统内平流能量和树木位置对树木蒸腾速率的影响程度。我们主要研究了一种优势种（saccharinum Acer）和一种亚优势种（Juglans nigra）的水分利用响应（用热比法测定）。在较短的时间内，对另外三种（双色栎、黑桦树、西洋Platanus occidentalis）的少数个体进行了监测，以评估反应的普遍性。沿河岸缓冲区的样带设置了气象站，以确定小气候条件。个体间的差异主要是由于物种液速和边材深度、相对于森林边缘的位置和盛行风、冠层暴露和优势度的差异。在东南缘（盛行风）生长的糖蜜树的树流率比东南缘高39%，比西北缘和内缘高30%和69%。在亚优势型黑穗槐中没有发现因边缘效应而导致的蒸腾增强。结果被解释为表明来自周围作物的平流效应。此外，五个研究物种之间的水流速率存在显著差异，表明物种选择对增强特定的河岸缓冲功能很重要。但是，还需要更多关于不同气候和生物物理条件下生长的不同物种的水利用模式的信息，以协助有关有效缓冲区设计的政策和管理决策。
Riparian buffers are designed as management practices to increase infiltration and reduce surface runoff and transport of sediment and nonpoint source pollutants from crop fields to adjacent streams. Achieving these ecosystem service goals depends, in part, on their ability to remove water from the soil via transpiration. In these systems, edges between crop fields and trees of the buffer systems can create advection processes, which could influence water use by trees. We conducted a field study in a riparian buffer system established in 1994 under a humid temperate climate, located in the Corn Belt region of the Midwestern U.S. (Iowa). The goals were to estimate stand level transpiration by the riparian buffer, quantify the controls on water use by the buffer system, and determine to what extent advective energy and tree position within the buffer system influence individual tree transpiration rates. We primarily focused on the water use response (determined with the Heat Ratio Method) of one of the dominant species (Acer saccharinum) and a subdominant (Juglans nigra). A few individuals of three additional species (Quercus bicolor, Betula nigra, Platanus occidentalis) were monitored over a shorter time period to assess the generality of responses. Meteorological stations were installed along a transect across the riparian buffer to determine the microclimate conditions. The differences found among individuals were attributed to differences in species sap velocities and sapwood depths, location relative to the forest edge and prevailing winds and canopy exposure and dominance. Sapflow rates for A. saccharinum trees growing at the SE edge (prevailing winds) were 39% greater than SE interior trees and 30% and 69% greater than NW interior and edge trees, respectively. No transpiration enhancement due to edge effect was detected in the subdominant J. nigra. The results were interpreted as indicative of advection effects from the surrounding crops. Further, significant differences were document in sapflow rates between the five study species, suggesting that selection of species is important for enhancing specific riparian buffer functions. However, more information is needed on water use patterns among diverse species growing under different climatic and biophysical conditions to assist policy and management decisions regarding effective buffer design.