Allocation Strategies for Seed Nitrogen and Phosphorus in an Alpine Meadow Along an Altitudinal Gradient on the Tibetan Plateau

Abstract

Nitrogen (N) and phosphorus (P) play important roles in many aspects of plant biology. The allocation of N and P in plant vegetative organs (i.e., leaves, stems, and fine roots) is critical to the regulation of plant growth and development. However, how these elements are allocated in seeds is unclear. The aim of this study was to explore the N and P allocation strategies of seeds in an alpine meadow along an altitudinal gradient. We measured the seed N and P contents of 253 herbaceous species in 37 families along an altitudinal gradient (2,000–4,200 m) in the east Tibetan alpine meadow. The geometric means of seed N and P concentrations and N:P ratios were 34.81 mg g–1, 5.06 mg g–1, and 6.88, respectively. Seed N and P concentrations varied across major taxonomic groups and among different altitude zones. N:P ratios showed no significant variations among different taxonomic groups with the exception of N-fixing species. The numerical value of the scaling exponent of seed N vs. P was 0.73, thus approaching 3/4, across the entire data set, but varied significantly across major taxonomic groups. In addition, the numerical value of the scaling exponent of N vs. P declined from 0.88 in the high altitude zone to 0.63 in the low altitude zone. These results indicate that the variations in the numerical value of the scaling exponent governing the seed N vs. P scaling relationship varies as a function of major taxonomic groups and among different altitude zones. We speculate that this variation reflects different adaptive strategies for survival and germination in an alpine meadow. If true, the data presented here advance our understanding of plant seed allocation strategies, and have important implications for modeling early plant growth and development.

Allometry and Distribution of Nitrogen in Natural Plant Communities of the Tibetan Plateau

“…The climate and soil conditions in TP are relatively unsuitable for plant growth due to the high altitude; at high altitudes, the nutrient turnover rate decreases and the nutrient cycle process slows down ( Reich and Oleksyn, 2004 ). Plants have evolved unique survival mechanisms to adapt to distinct habitats with special characteristics such as high altitude and low temperature as in TP ( Wang et al, 2020 ). Climate change including global warming and increasing snow depth significantly affected N leaf in the tundra ( Welker et al, 2005 ) while enhanced radiation significantly increases the N leaf partition coefficient ( Sullivan et al, 2003 ).…”

“…N is associated with the rate of photosynthesis, and total carbohydrate storage in leaves, branch, trunk, and roots ( Wang et al, 2020 ). The allocation of N among plant organs undoubtedly reflects the adaptation strategies of natural communities at a large scale.…”

Divergent nitrogen and phosphorus allocation strategies in terrestrial plant leaves and fine roots: A global meta‐analysis

“…The allocation of N and P at the whole plant level involves the allocation of different nutrients to specific organ types and the allocation of the same element among different organ types (Yang et al, 2014). Previous studies of N and P allocation have tended to focus on allocation within a single organ type, including leaves (Han et al, 2005; McGroddy et al, 2004; Niklas et al, 2005; Reich et al, 2010; Reich & Oleksyn, 2004; Tian et al, 2018), stems (Niklas & Cobb, 2005; Wang et al, 2018; Wang, Niklas, et al, 2022; Zhang, He, et al, 2018; Zhao et al, 2016), fine roots (Wang et al, 2019; Yuan et al, 2011; Zhao et al, 2021) and seeds (Wang, Bu, et al, 2020). Although a limited number of studies have investigated N and P allocation strategies among several organs (leaves, stems and roots; Kerkhoff et al, 2006; Yan et al, 2016; Yang et al, 2014), comparatively little is known about how the N and P are allocated between leaves and fine roots (Zhao et al, 2019).…”

“…The allocation of N and P at the whole plant level involves the allocation of different nutrients to specific organ types and the allocation of the same element among different organ types (Yang et al, 2014). Previous studies of N and P allocation have tended to focus on allocation within a single organ type, including leaves (Han et al, 2005;McGroddy et al, 2004;Reich et al, 2010;Reich & Oleksyn, 2004;Tian et al, 2018), stems Wang et al, 2018;Zhang, He, et al, 2018;Zhao et al, 2016), fine roots (Wang et al, 2019;Yuan et al, 2011;Zhao et al, 2021) and seeds (Wang, Bu, et al, 2020).…”

Effects of increased phosphorus fertilizer on C, N, and P stoichiometry in different organs of bluegrass (Poa L.) at different growth stages

“…In addition, the difference in genetic backgrounds in plants affects their survivability and reproductivity. Plants constantly adjust the distribution of their nutrient content to adapt to environmental changes at different growth stages, which results in differences in nutrient content and stoichiometric ratios in plants at different reproductive stages (Gao et al, 2019;Lu et al, 2019;Wang et al, 2020a). The C:N:P stoichiometric ratio of plants is greatly affected by nutrient availability, which can reflect the chemical element cycle between the environment and plants.…”