Limitations to sub-boreal forest growth and carbon sequestration from tree to forest scale before and after natural and anthropogenic disturbances.

不列颠哥伦比亚省中部的森林在就业、当地国民经济、生物能源、纤维和木制品生产和出口、生物多样性、娱乐、非木材产品和温室气体减排等方面一直是、而且仍然是非常重要的可持续资源。然而，这些森林的未来取决于我们对森林健康、生长和不断变化的环境(例如气候变化：特别是温度和水)之间关系的理解。同样重要的还有森林多样性的变化以及树木和非树木物种之间的相互作用、营养动态(例如，来自固氮生物的氮(N)输入)、干扰制度(例如，火)、收获系统等。我提议的研究将涉及一系列问题，这些问题对于理解过去、现在和未来的限制和变化如何影响/影响/将影响重要的亚北方森林类型及其生产力至关重要。我的研究目标是：*1.利用森林林分水平的CO2和H2O交换来验证和校准亚北方森林的林分水平的生长和生产力。将测量树木层面的CO2和H2O交换，每日到每年的树干直径变化(径向生长)，以及关键的地上和地下植物的树干CO2和H2O通量测量(例如，树液通量和/或气体交换)。这些将被扩大到标准水平(例如，使用Bowler等人采取的方法)。2012年)。到2016年，我将有9到10年的连续森林尺度涡旋协方差二氧化碳和H2O通量测量，树冠测量(例如，死亡树木的活体与死亡的比率)，以及涡旋协方差通量塔址的地下呼吸，在我提议的研究期间，测量将继续进行，这是基于2015年CFI授予UBC合作者的奖项。*2.通过检测径向生长(例如，树干年代学和/或树干径向生长)来研究树栖固氮蓝藻(从低到高的树高丰度)对云杉和冷杉生长的影响。将根据附生的蓝藻生物量负荷和土壤和寄主树木的树木水平的N输入和N条件来检查树木到林分水平的生长和N含量。将审查落叶(非作物)物种的重要性，例如在与针叶树种相邻的杨属中，研究它们在促进从树木到景观尺度的蓝藻负荷和针叶树生长速度方面的作用。大气氮沉积(湿的和干的)将在实验树和场地或景观水平上确定。我计划使用稳定的同位素(自然丰度和/或可能的浓缩)来澄清营养交换的方向和程度。将在田间建立树木上附生植物负荷的长期操作，特别是蓝藻，并评估N输入的变化，以及随后的附生植物演替。

Forests in central British Columbia have been and remain a tremendously important and sustainable resource for employment, local to national economies, bioenergy, fibre and wood product production and export, biodiversity, recreation, non-timber products, and greenhouse gas mitigation to name a few. However, the future of these forests is dependent upon our understanding of the relationships between forest health, growth, and a changing environment (e.g. climate change: notably temperature and water). Also important are changes in forest diversity and interactions in and between tree and non-tree species, nutrient dynamics (e.g. nitrogen (N) inputs such as from N2-fixing organisms), disturbance regimes (e.g. fire), harvesting systems, and others. My proposed research will address a range of questions that will be critical for understanding how limitations and changes in past, present and future have affected/affect/will affect important sub-boreal forest types and their productivities. My research objectives are:***1. To use forest stand-level CO2 and H2O exchange to corroborate and calibrate tree- to stand-level growth and productivity of sub-boreal forests. CO2 and H2O exchange at the tree-level, daily to annual stem diameter changes (radial growth), and CO2 and H2O flux measurements for stem (e.g. sap flux and/or gas-exchange) for key over- and under-story plants will be measured. These will be scaled up to stand-level (e.g. using approaches taken in Bowler et al. 2012). I will have 9 to 10 years of continuous forest-scale eddy-covariance CO2 and H2O flux measurement, canopy measurement (e.g. live versus dead, fall-down rates of dead trees) and belowground respiration for the an eddy-covariance flux tower site by 2016, with measurements continuing for the duration of my proposed research based on a 2015 CFI award to collaborators at UBC. ***2. To examine the impact of arboreal N2-fixing cyanolichens (low to high tree-level abundance) on growth of spruce and fir by examining radial growth (e.g. dendrochronology and/or dendrometer). Tree- to stand-level growth and N content will be examined relative to epiphytic cyanolichen biomass loading and tree-level N inputs and N conditions of the soil and host trees. Importance of deciduous (non-crop) species such as in the genus Populus adjacent to conifer species will be examined for their roles in facilitating cyanolichen loading and conifer growth rates from tree to landscape scale. Atmospheric N deposition (wet and dry) will be determined at the experimental tree and site or landscape level. I plan to use stable isotopes (natural abundance and/or possibly enrichment) to clarify directions and magnitudes of nutrient exchanges. Long-term manipulations of epiphyte loadings on trees, particularly cyanolichen, will be established in the field and changes to N inputs evaluated, as well as subsequent epiphyte succession.**