Interspecific and intraspecific variation in leaf toughness of Arctic plants in relation to habitat and nutrient supply

Ned Fetcher,Thomas C Parker,Sofia Iglesia,Stephen J Turner

doi:10.1139/as-2020-0016

Ned Fetcher, Thomas C Parker + Show 2 more

Open Access

https://doi.org/10.1139/as-2020-0016

Copy DOI

Abstract

Leaf toughness is an important functional trait that confers resistance to herbivory and mechanical damage. We sought to determine how species composition, climate, seasonality, and nutrient availability influence leaf toughness in two types of tundra in northern Alaska. We measured leaf toughness as force to punch for 11 species of Arctic plants in tussock tundra and dry heath tundra at 17 sites distributed along a latitudinal gradient. Rubus chamaemorus L. and the graminoids occupied opposite ends of the leaf toughness spectrum, with Rubus chamaemorus requiring the least force to punch, whereas one of the graminoids, Eriophorum vaginatum L., required the most. Leaf toughness increased with mean summer temperature for Eriophorum vaginatum and Betula nana L., whereas it declined with warmer temperatures for the other species. Toughness of mature leaves of Eriophorum vaginatum did not vary through the growing season but declined significantly after senescence. Application of N and P fertilizer in an experimental site decreased leaf toughness in three species but had no effect on four others. Leaf toughness of four out of five species in dry heath was greater than for the same species in tussock tundra, but there was no difference in community-weighted mean toughness between tussock tundra and dry heath.

Highlights

Surveys of plant traits such as plant height and specific leaf area have great potential to provide insight into the functioning of Arctic ecosystems and inform predictions of their response to climate change (Bjorkman et al 2018a; Myers-Smith et al 2019)
We address the following questions: (1) How does leaf toughness vary between common tundra plants? (2) Is there latitudinal, seasonal, or yearly variation in leaf toughness? (3) Is there a difference in leaf toughness between tussock tundra and dry heath? (4) Is there a difference in community-weighted mean toughness between vegetation types? (5) What is the effect of added nutrients on leaf toughness? (6) How much does intraspecific variation contribute to variation in leaf toughness within communities?
We examined the effect of species and climate on leaf toughness in tussock tundra (Questions 1 and 2) measured at twelve sites in late June and early July for five widely distributed species, Betula nana L., Carex bigelowii Torr. ex Schwein., Eriophorum vaginatum, Rhododendron tomentosum Harmaja, and Vaccinium vitis-idaea L. (Table 1)

Summary

Introduction

Surveys of plant traits such as plant height and specific leaf area have great potential to provide insight into the functioning of Arctic ecosystems and inform predictions of their response to climate change (Bjorkman et al 2018a; Myers-Smith et al 2019). Functional traits associated with leaves affect rates of photosynthesis and decomposition, whereas traits associated with plant stature can affect canopy height and leaf area index, all of which can impact carbon storage (Myers-Smith et al 2019). Belowground traits such as rooting depth can influence the acquisition of nitrogen (Hewitt et al 2019). In an extensive review, Onoda et al (2011) examined interspecific trends in leaf toughness in response to latitudinal, temperature, and precipitation gradients They did not find a significant trend with respect to latitude or temperature, but they did find that leaf toughness increased with decreasing mean annual precipitation. Studies of functional traits in the Arctic have not included measures of leaf toughness (Bjorkman et al 2018a, 2018b)

Methods

Results

Conclusion