Boyce Thompson Institute for Plant Research, Cornell Univeristy, 14853, Ithaca, NY, USA.
Environ Monit Assess. 1989 Apr;12(1):63. doi: 10.1007/BF00396733.
Substantial and widespread morbidity and mortality of red spruce have been observed in high elevation forests of the northeast under circumstances indicative of a stress-related disease. Whether red spruce at lower elevations are experiencing a more subtle loss of growth and vigor is uncertain. In addition, sugar maple has exhibited decline of varying extent and intensity for several decades. Forests in the northeast are exposed to two air pollutants, ozone (O3) and acidic precipitation, that are widespread in occurrence and have the potential, both individually and collectively, to produce impacts to forest trees. the roles, if any, of these two stress agents in the tree declines found in the northeast are not known.In 1986, a five-year study was initiated to evaluate the effects of O3 and acidic precipitation on red spruce and sugar maple. The trees will be exposed to controlled levels of O3 and acidic precipitation in the field using open-top chambers. The experiment is a 4×3 factorial conducted in split plots with O3 treatments as whole plots and simulated rain treatments comprising the split plots. Broadly stated, the research will evaluate the effects of the pollutants on the processes, fluxes, and pools associated with carbon, water, and nutrients in the soil/tree/atmosphere system. These evaluations will be conducted on a systems level and will be integrated through the development of mechanistic simulation models.Assessment of the effects of the treatments on carbon fixation by photosynthesis, the loss of carbon through respiration, and the allocation of carbon in growth will be a central focus of the study. Whole-tree cuvettes will be used to assess net photosynthesis, respiration, transpiration, and stomatal conductance.Considerable emphasis will be placed on determining the influences of the treatments on the biogeochemistry of the system. These studies will focus on the leaching of nutrients from the tree canopy, the mobilization and loss of nutrients from the soil, soil solution chemistry, and the alteration of tree nutrition by the input of additional nitrogen in precipitation.Statistical and simulation modeling will be used to assess and describe the effects of the treatments. The modeling approaches are different in technique, but complementary. Statistical models will be used to describe the responses of growth and physiological variables to the ozone and acidic precipitation treatments. Simulation models will be built to describe the relationships between photosynthesis, respiration, nutrition, and water use, how these processes are affected by the treatments, and how these effects ultimately result in altered growth. The simulation models will initially provide a framework for the formulation of hypotheses regarding the interrelationships of plant components and processes and how they are affected by the treatments.
在东北高海拔森林中，观察到红云杉出现了大量广泛的发病率和死亡率，这些情况表明存在与压力相关的疾病。目前还不确定在较低海拔地区的红云杉是否经历了更微妙的生长和活力丧失。此外，糖枫几十年来一直在不同程度和强度上出现衰退。东北的森林暴露在两种空气污染物中，臭氧（O3）和酸性沉降物，它们广泛存在，并且具有对森林树木产生影响的潜力，无论是单独作用还是共同作用。这两种应激剂在东北发现的树木衰退中所起的作用尚不清楚。1986 年，启动了一项为期五年的研究，以评估 O3 和酸性沉降物对红云杉和糖枫的影响。将使用开顶式气室在野外对树木进行受控水平的 O3 和酸性沉降物处理。该实验是一个 4×3 析因设计，以 O3 处理作为全区组，模拟降雨处理作为裂区。广义而言，该研究将评估污染物对土壤/树木/大气系统中与碳、水和养分相关的过程、通量和库的影响。这些评估将在系统水平上进行，并通过开发机制模拟模型进行整合。评估处理对光合作用固定碳、呼吸作用损失碳以及生长中碳分配的影响将是该研究的一个重点。整树箱将用于评估净光合作用、呼吸作用、蒸腾作用和气孔导度。将非常重视确定处理对系统生物地球化学的影响。这些研究将集中在营养元素从树冠淋失、土壤中营养元素的迁移和损失、土壤溶液化学以及降水输入额外氮对树木营养的改变上。统计和模拟建模将用于评估和描述处理的影响。建模方法在技术上有所不同，但互补。统计模型将用于描述生长和生理变量对 O3 和酸性沉降物处理的响应。模拟模型将用于描述光合作用、呼吸作用、营养和水分利用之间的关系，以及这些过程如何受到处理的影响，以及这些影响最终如何导致生长的改变。模拟模型最初将为制定关于植物成分和过程的相互关系以及它们如何受到处理影响的假设提供框架。
