Data from: The role of plant-soil feedbacks in stabilizing a reindeer-induced vegetation shift in subarctic tundra

1.Herbivory can drive vegetation into different states of productivity and community composition, and these changes may be stable over time due to historical contingency effects. Interactions with abiotic and biotic soil components can contribute to such long‐term legacies in plant communities through stabilizing positive feedbacks.

2.We studied the role of plant‐soil feedbacks in maintaining vegetation changes caused by historical (~1350‐1900 AD) reindeer herding in northern Sweden. These historical milking grounds (HMGs) consist of meadow plant communities formed in naturally nutrient poor heath or naturally nutrient rich shrub‐dominated vegetation, and are still clearly visible in the landscape, a century after active use ceased.

3.We selected two phytometer species: the forb Potentilla crantzii as representative of HMG vegetation, and the dwarf shrub Betula nana, as representative of control vegetation. We grew both species under glasshouse conditions on soils derived from replicated HMG and paired control plots, using live soils and sterilized (γ‐radiation)‐inoculated soils, to separate between biotic and abiotic soil effects.

4.A net negative plant‐soil feedback for B. nana biomass in its home (i.e., control) soil and a net positive feedback for P. crantzii in its home (i.e., HMG) soil in heath habitat was partly driven by the soil biotic community. However, abiotic differences in mineral nitrogen (N) concentrations between control and HMG soils were a stronger driver of differences in plant growth. Positive feedbacks maintaining a high mineral nutrient availability are thus important, especially in nutrient poor habitats.

5.The positive plant responses to higher soil mineral N concentrations, combined with positive biotic plant‐soil feedbacks, might shift the competitive balance in favour of typical HMG plant species, thereby contributing to stability of HMG plant communities. Our data indicate that herbivore‐driven changes in the interactions between plants and both biotic and abiotic components of the soil persist over long temporal scales.

1. 植食作用可将植被驱动至不同的生产力状态与群落组成结构，而由于历史偶然性效应，这些变化可能长期保持稳定。植物与非生物、生物土壤组分的相互作用，可通过稳定的正反馈过程，在植物群落中形成此类长期遗留效应。
2. 本研究聚焦于植物-土壤反馈（plant-soil feedbacks）在维持瑞典北部历史时期（约公元1350-1900年）驯鹿放牧所引发的植被变化中的作用。这些历史挤奶场（historical milking grounds, HMGs）是由自然养分匮乏的石楠灌丛或自然养分充足的灌丛主导植被发育而来的草甸植物群落，即便在放牧活动停止一个世纪后的当下，其在地表景观中仍清晰可辨。
3. 本研究选取两种指示植物种：代表历史挤奶场植被的草本委陵菜（Potentilla crantzii），以及代表对照植被的矮桦（Betula nana）。我们将这两个物种分别种植于温室培养条件下的土壤中，这些土壤取自重复设置的历史挤奶场样地及其配对对照样地，同时设置活体土壤与经γ辐射灭菌的接种土壤处理组，以区分土壤生物与非生物因子的效应。
4. 在石楠灌丛生境中，矮桦在其原生（即对照）土壤中表现为净负植物-土壤反馈，而委陵菜在其原生（即历史挤奶场）土壤中表现为净正植物-土壤反馈，这一现象部分由土壤生物群落介导。然而，对照样地与历史挤奶场土壤间的矿质氮（mineral nitrogen, N）浓度非生物差异，对植物生长差异的驱动作用更为显著。由此可见，维持高矿质养分有效性的正反馈过程至关重要，在养分匮乏的生境中尤为如此。
5. 植物对更高土壤矿质氮浓度的正向响应，结合正向生物介导的植物-土壤反馈，可能会改变竞争平衡，使典型历史挤奶场植物物种更具竞争优势，进而助力历史挤奶场植物群落的稳定性。本研究数据表明，植食动物驱动的植物与土壤生物、非生物组分间的相互作用变化，可在长时间尺度上持续存在。