Complementarity of gymnosperm and angiosperm trees in space and time

裸子植物和被子植物在空间和时间上的互补性

• 批准号: RGPIN-2020-04670
• 负责人: nock, charles
• 金额: $ 2.4万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=716656
• 关键词: Complementarity; gymnosperm; angiosperm; trees; space

Forests provide a multitude of essential services to humanity. Forest productivity has long been of interest due to the value of wood as a commodity, and more recently due to the central role of forests in the global carbon cycle. Enhanced productivity of mixtures of tree species, or overyielding, has often been linked to the complementary use of light or nutrients by different tree species possessing different traits or characteristics. In particular, complementarity in mixtures of conifer (evergreen) and deciduous (broadleaf) species has been linked to overyielding in both managed forests and in field experiments. The long-term objective of the proposed research program is to improve our understanding of the relationships among tree diversity, productivity and the resilience of tree growth. In the short-term, existing field experiments will be used to address the following objectives (1) to determine the influence of allometric uncertainty of tree biomass estimation on diversity effects, (2) to quantify the roles of spatial and temporal complementarity for overyielding in tree communities, and, (3) to test how diversity influences the resilience and temporal stability of community productivity. To address (1), allometric equations that relate tree dimensions (diameter, height) to biomass will be developed for each species in a mixture, and how the precision of these equations influence interpretations of selection and complementarity effects will be examined. To address (2) we will quantify complementarity in canopy space by measuring the overlap of tree crowns and then calculating an index of the overlap for the community. We will also extend this index to include temporal complementarity, by also quantifying when tree crowns flush leaves in the spring and shed leaves in the autumn. Finally, we will test if including the flushing and shedding information helps us make better predictions of the growth of functionally diverse tree communities. To address (3), the effects of within-species and between-species competition on the level of tree growth and the variability tree growth will be studied in a long-running experiment with aspen-spruce mixtures. The proposed research will contribute new knowledge to fundamental questions that are central to understanding relationships between tree diversity and forest productivity. Practical knowledge resulting from these studies will help manage forests in the face of stress due to global warming, by informing what stand compositions should be promoted to reduce drought impacts on tree growth.

森林为人类提供了许多基本服务。由于木材作为一种商品的价值，以及最近由于森林在全球碳循环中的核心作用，森林生产力长期以来一直受到关注。混合树种生产力的提高或产量过剩，往往与具有不同性状或特性的不同树种互补利用光或养分有关。特别是，针叶树（常绿）和落叶（阔叶）物种混合的互补性与管理森林和田间试验中的超产有关。该研究计划的长期目标是提高我们对树木多样性、生产力和树木生长弹性之间关系的理解。在短期内，现有的野外实验将用于解决以下目标：(1)确定树木生物量估算的异速不确定性对多样性效应的影响；(2)量化树木群落中超产的时空互补性的作用；(3)测试多样性如何影响群落生产力的恢复力和时间稳定性。为了解决(1)，将为混合物中的每个物种开发与树木尺寸（直径、高度）与生物量相关的异速生长方程，并将检查这些方程的准确性如何影响对选择和互补效应的解释。为了解决(2)问题，我们将通过测量树冠的重叠来量化树冠空间的互补性，然后计算群落的重叠指数。我们还将扩展这一指数，包括时间上的互补性，同时量化树冠在春天冲洗叶子和秋天落叶的时间。最后，我们将测试包括冲洗和脱落信息是否有助于我们更好地预测功能多样化的树木群落的生长。为了解决(3)，我们将在一项长期的白杨-云杉混合试验中研究种内和种间竞争对树木生长水平和树木生长变异性的影响。拟议的研究将为理解树木多样性和森林生产力之间关系的核心基本问题提供新的知识。这些研究产生的实用知识将有助于管理面临全球变暖压力的森林，告知应促进何种林分组成以减少干旱对树木生长的影响。