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Abstract Arctic rodents influence tundra plant communities by altering species diversity, structure, and nutrient dynamics. These dynamics are intensified during rodent population peaks. Plants are known to induce defenses in response to rodent herbivory. However, changes in plant tissue digestibility may also play a role in deterring rodents or impacting their survival. This study presents a first look at the impacts of rodent herbivory on crude protein (CP) and acid detergent fiber (ADF) of two of the most common graminoid species (Carex nigraandDeschampsia cespitosa) and graminoid genus (Calamagrostisspp.) in the tundra meadows of the Varanger Peninsula, Norway. We selected 32 experimental plots representing both rodent-disturbed and adjacent, undisturbed control graminoid patches. In the summer of a rodent population peak, the disturbed plots had higher ADF (28.5%) values than less disturbed ones (26.6%), controlling for plant species. We also found differences between species, withCarex nigrahaving the lowest fiber content (24.3%, ADF) and highest protein content (18.2% CP)—making it the most palatable species. These results show that rodent activity can potentially alter plant food quality, suggesting that increasing fiber content may be a defensive response to herbivory.
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This content will become publicly available on November 14, 2026
Forbs in Viking lands: the effect of disturbing dominant graminoids on recruitment in tundra grasslands
Grasslands, by definition, are dominated by graminoids. Nevertheless, forbs also make up a substantial part of vascular plant diversity in grasslands and are important resources of mammalian herbivores. However, forb recruitment is constrained by successful dominant graminoids, limiting access to safe sites for germination. Disturbances created by herbivores can reduce graminoid dominance and favor forb recruitment. Here we hypothesize that intense disturbance, such as that caused by megaherbivores, promotes safe sites for forbs in such graminoid‐dominated grasslands, whereas disturbance by today's herbivores, such as small rodents, may not be sufficiently intense. We selected a total of 80 plots with either of four successful graminoid species in tundra grasslands of the Varanger Peninsula, Norway. The graminoid species were silicon‐poor or rich, and of either mat‐ or bunch‐growth form. Plots were further selected in both rodent disturbed and undisturbed areas. We manually removed the dominant graminoid in half of the plots, mimicking megaherbivore disturbance by reducing both shading capabilities and belowground rhizome and root systems. Results show that forb recruitment was significantly enhanced one year following the manual removal of all four graminoids. This effect on forb recruitment was similar among the four graminoids even though they were associated with distinct plant communities. The rodent disturbance did not enhance forb recruitment. In plots with rodent‐disturbed graminoids, the manual removal enhanced forb recruitment only in plots with silicon‐rich graminoids. Forb recruitment was further enhanced by higher levels of initial species richness, initial forb abundance, and soil moisture. Our findings support the hypothesis that intense disturbance, simulating megaherbivore effects on dominant graminoids, significantly enhances forb recruitment.
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- Award ID(s):
- 2126796
- PAR ID:
- 10654855
- Publisher / Repository:
- Oikos
- Date Published:
- Journal Name:
- Oikos
- ISSN:
- 0030-1299
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Arctic rodents influence tundra plant communities by altering species diversity, structure, and nutrient dynamics. These dynamics are intensified during rodent population peaks. Plants are known to induce defenses in response to rodent herbivory. However, changes in plant tissue digestibility may also play a role in deterring rodents or impacting their survival. This study presents a first look at the impacts of rodent herbivory on crude protein (CP) and acid detergent fiber (ADF) of three of the most common graminoid species (Calamagrostis sp.,Carex nigraandDeschampsia cespitosa) in the tundra meadows of the Varanger Peninsula, Norway. We selected 32 experimental plots representing both rodent-disturbed and adjacent, undisturbed control graminoid patches. During a rodent population peak, the disturbed plots had higher ADF (28.5%) values than less disturbed ones (26.6%), controlling for plant species. We also found differences between species, withCarex nigrahaving the lowest fiber content (24.3%, ADF) and highest protein content (18.2% CP) – making it the most palatable species. These results show that rodent activity can potentially alter plant food quality, suggesting that increased fiber content may be a defensive adaptation against herbivory.more » « less
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