Ecological significance of plant biomass turnover

植物生物量周转的生态意义

• 批准号: RGPIN-2017-06011
• 负责人: Ryser, Peter
• 金额: $ 1.75万
• 依托单位: Laurentian University of Sudbury
• 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=711918
• 关键词: Ecological; significance; plant; biomass; turnover

In climates that have favourable and unfavourable seasons, plant behaviour shows seasonal patterns of growth and senescence. Responses to the seasons may vary from species to species, a well-known example being the contrasting habits of deciduous and evergreen trees with either autumn-senescing or overwintering leaves. There are indications that roots of wetland plants show a similar dichotomous choice of overwintering behavior: the entire root system either senesces in the autumn, or it largely survives the winter. But while the adaptive value of leaf turnover pattern in different environments is well understood, for roots less information is available. Not even the timing of root production and root senescence is well known. Nevertheless, recent research has shown that root behaviour can considerably differ from turnover patterns of the above-ground plant parts. This research program will address the issue of root turnover in a two-fold manner. The first approach is to describe in detail patterns of root production and senescence over the year, and to understand how these patterns respond to variation in soil temperature and growing season length. This will be investigated in outdoor experiments in an experimental garden by manipulating soil temperature, and in semi-controlled field experiments in different climate zones, the locations ranging from the James Bay coast to the southeastern US. The second approach will be to investigate the functional consequences of variation in seasonal patterns of growth and senescence of roots. Roots take up mineral nutrients from the soil, the availability of which varies depending of the season. We will investigate how the timing of root production and senescence affects nutrient uptake over a year, using the stable isotope technique. We will also investigate how the residence time of nitrogen in the plant varies among plant species with different root turnover patterns. The warming climate will lead to changes in growing season length and in seasonal patterns of plant behavior. Understanding these processes is essential to predict effects of climate change on ecosystem processes such as carbon cycling. Current models are mostly based on above-ground data, as data on below-ground processes is scarce. The research proposed here will contribute to a better understanding of below-ground processes in wetlands in response to temperature and growing season length. The expected results will help to make accurate predictions of root turnover, and the resulting carbon cycling and sequestration in these wetlands, which cover large areas in Canada's North.

在有利和不利季节的气候中，植物的行为表现出季节性的生长和衰老模式。对季节的反应可能因物种而异，一个众所周知的例子是落叶树和万年青树的不同习性，它们的叶子要么是秋天衰老的，要么是越冬的。有迹象表明，湿地植物的根系表现出类似的越冬行为的二分法选择：整个根系要么在秋季衰老，要么在很大程度上生存的冬天。但是，虽然叶周转模式在不同环境中的适应性价值是很好的理解，根的信息很少。甚至连根产生和根衰老的时间也不清楚。然而，最近的研究表明，根的行为可以大大不同的周转模式的地上植物部分。 这项研究计划将以双重方式解决根周转问题。第一种方法是详细描述一年中根的产生和衰老的模式，并了解这些模式如何对土壤温度和生长季节长度的变化作出反应。这将在实验花园的室外实验中通过操纵土壤温度进行研究，并在不同气候区的半控制田间实验中进行研究，这些气候区的位置从詹姆斯湾海岸到美国东南部。第二种方法将是调查根的生长和衰老的季节性模式的变化的功能后果。根从土壤中吸收矿物质营养，其可用性因季节而异。我们将研究如何根生产和衰老的时间影响养分吸收超过一年，使用稳定同位素技术。我们还将研究氮在植物中的停留时间如何在具有不同根周转模式的植物物种之间变化。 气候变暖将导致生长季节长度和植物行为的季节性模式的变化。了解这些过程对于预测气候变化对碳循环等生态系统过程的影响至关重要。目前的模型大多以地面数据为基础，因为关于地下过程的数据很少。这里提出的研究将有助于更好地了解地下过程中的湿地温度和生长季节的长度。预期的结果将有助于准确预测根周转，以及由此产生的碳循环和封存在这些湿地，覆盖加拿大北部的大面积。