Abstract
Nitrogen (N) is an important element for most terrestrial ecosystems; its variation among different plant organs, and allocation mechanisms are the basis for the structural stability and functional optimization of natural plant communities. The nature of spatial variations of N and its allocation mechanisms in plants in the Tibetan Plateau—known as the world’s third pole—have not been reported on a large scale. In this study, we consistently investigated the N content in different organs of plants in 1564 natural community plots in Tibet Plateau, using a standard spatial-grid sampling setup. On average, the N content was estimated to be 19.21, 4.12, 1.14, and 10.86 mg g–1 in the leaf, branch, trunk, and root, respectively, with small spatial variations. Among organs in communities, leaves were the most active, and had the highest N content, independent of the spatial location; as for vegetation type, communities dominated by herbaceous plants had higher N content than those dominated by woody plants. Furthermore, the allocation of N among different plant organs was allometric, and not significantly influenced by vegetation types and environmental factors; the homeostasis of N was also not affected much by the environment, and varied among the plant organs. In addition, the N allocation strategy within Tibet Plateau for different plant organs was observed to be consistent with that in China. Our findings systematically explore for the first time, the spatial variations in N and allometric mechanisms in natural plant communities in Tibet Plateau and establish a spatial-parameters database to optimize N cycle models.
Highlights
Nitrogen (N) is an essential nutrient for plant growth and survival, and is an important element limiting productivity in most terrestrial ecosystems (Xu et al, 2020; Xu and He, 2020)
Our findings systematically explore for the first time, the spatial variations in N and allometric mechanisms in natural plant communities in Tibet Plateau and establish a spatial-parameters database to optimize N cycle models
Most of the above studies on N content and distribution are at the species scale, on the basis of the biochemical conversion of N during the protein synthesis process, it is speculated that the interrelation among N allocation to different organs in community may be conserved to some extent
Summary
Nitrogen (N) is an essential nutrient for plant growth and survival, and is an important element limiting productivity in most terrestrial ecosystems (Xu et al, 2020; Xu and He, 2020). The allocation of N among plant organs undoubtedly reflects the adaptation strategies of natural communities at a large scale. One of the nutrient allocation strategies adopted by plants is that more active organs are allocated more nutrients (Zhang et al, 2018); it is presumed that in terms of N content, the leaves and roots contain higher N than the branches and stems. Adjusting N allocation rates among different organs is an important way for plants to adapt to their environment. Most of the above studies on N content and distribution are at the species scale, on the basis of the biochemical conversion of N during the protein synthesis process, it is speculated that the interrelation among N allocation to different organs in community may be conserved to some extent
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