Nitrogen cycling and storage in Gagea spathacea (Liliaceae): ecological insights for protecting a rare woodland species

作者：Fichtner Andreas; Matthies Diethart; Armbrust Malin; Jansen Doris; Sturm Knut; Walmsley David; von Oheimb Goddert; Haerdtle Werner

来源：Plant Ecology, 2018, 219(9): 1117-1126.

DOI：10.1007/s11258-018-0863-x

• Ancient woodland
• Convention on Biological Diversity
• Nitrogen allocation
• Nitrogen recycling
• N-15
• Stable isotope

Strategies to globally protect biological diversity are often hampered by an insufficient ecological knowledge about target species. This also applies to Gagea spathacea (Liliaceae), a 'vulnerable' woodland spring geophyte with a distribution largely restricted to the lowlands of Central Europe. We studied whether the species' linkage to highly fertile forest soils is related to its high nitrogen (N) demands during its short developmental cycle. We hypothesized that the species exhibits a highly efficient N (re)cycling strategy, characterized by efficient resorption of N from the leaves and reallocation to bulbs at the end of the growing season. To test this assumption, we conducted a N-15 tracer experiment and quantified N-15 flows between soil, leaves, bulbs, and roots. Our findings support our hypothesis that G. spathacea is exceptionally efficient in recycling N, shown by the resorption of 68% of leaf N and its reallocation to bulbs at the end of the growing season. After 6 weeks of growth the plant showed a distinct shift in its N metabolism: The C:N ratio of leaves strongly increased and those of bulbs decreased, leaf N-15 enrichment and recovery started to decrease, while total plant N-15 recovery remained constant, indicating no further N uptake from the soil. Leaf N reallocation to bulbs was accompanied by a twofold increase of the bulbs' biomass. Because of the stenoecious behaviour of G. spathacea, a careful protection and sustainable management of G. spathacea forest habitats is necessary, particularly in its Central European core area.

• 出版日期2018-9