Herbaceous Encroachment from Mountain Birch Forests to Alpine Tundra Plant Communities Through Above- and Belowground Competition

Abstract

Alpine plant communities are highly sensitive to global warming. One of the consequences of the warming is encroachment by herbaceous plants from forests at low elevations into alpine ecosystems. In the Changbai Mountains, narrowleaf small reed (Deyeuxia angustifolia (Kom.) Y. L. Chang) from mountain birch forests encroached upward into alpine tundra, gradually replacing native tundra shrubs such as Rhododendron (Rhododendron aureum Georgi). How encroaching plants affect native plant communities is not fully understood. In this study, we analyzed above- and belowground biomass of alpine plant communities at five encroachment levels to investigate how biomass allocation changed at species and community scales. Our research showed that native plants are forced to change their morphology to cope with competition, at both above- and belowground levels, from encroaching plants. We found that (1) R. aureum increased the shoot height and leaf area in order to compete with D. angustifolia; (2) above- and belowground biomass of D. angustifolia increased while above- and belowground biomass of R. aureum decreased with increasing levels of encroachment; and (3) D. angustifolia encroachment reduced the total biomass of alpine tundra. Encroachment by herbaceous plants has a long-term negative impact on the ability of tundra plants to sequester carbon in the alpine tundra of the Changbai Mountains.

Simulating potential impacts of climate changes on distribution pattern and carbon storage function of high‐latitude wetland plant communities in the Xing'anling Mountains, China

“…Under the warming climate, the southern D. angustifolia communities with higher competitive ability are predicted to migrate northwards where they could encroach on the local Sphagnum communities and expand to be the largest wetland plant community under three of the four climate scenarios by the end of 21st century, as shown in Figure 5. A similar phenomenon has been observed and reported in another main mountain range of Northeast China, the Changbai Mountains, where encroachment by D. angustifolia from forests at low elevations into tundra ecosystems has long‐term negative impact on soil properties and the carbon sequestration capacity of native plants (Berteaux et al, 2017; Tan et al, 2019). Sphagnum ‐dominated wetlands are the most efficient terrestrial ecosystems for storing carbon and contain up to 26% of all terrestrial carbon accumulated since the Last Glacial Maximum (Smith et al, 2004).…”

Winter belowground: Changing winters and the perennating organs of herbaceous plants

“…We can expect different responses by plants possessing different types of perennating organs (Lubbe & Henry, 2020), with variation both among species (Kong & Henry, 2019;Lubbe & Henry, 2019a&b) and within species (Clifton-Brown & Lewandowski, 2000). Importantly, variation in the effectiveness of these responses is anticipated to lead to vegetation changes (Komac et al, 2015;Tan et al, 2019;Joshi et al, 2020). For example, plants…”

“…We can expect different responses by plants possessing different types of perennating organs (Lubbe & Henry, 2020), with variation both among species (Kong & Henry, 2019; Lubbe & Henry, 2019a, 2019b) and within species (Clifton‐Brown & Lewandowski, 2000). Importantly, variation in the effectiveness of these responses is anticipated to lead to vegetation changes (Joshi et al., 2020; Komac et al., 2015; Tan et al., 2019). For example, plants with preformed structures within buds may be less plastic in their response to changes from year to year (Diggle, 1997; Werger & Huber, 2006) and be more vulnerable to unpredictable events.…”

Non-Structural Carbohydrate Storage Strategy Explains the Spatial Distribution of Treeline Species

“…Under the influence of a mountain climate and terrain, Changbai Mountains formed four distinct zones that range from low elevations to high elevations. The alpine tundra is above 2000 m, the B. ermanii forest zone is between 2000 m and 1700 m, the coniferous forest zone is from 1700 m to 1100 m, and the mixed deciduous broad-leaved/conifer forest zone is below 1100 m. B. ermanii is primarily distributed at 1700-2200 m, and P. jezoensis is primarily distributed at 1100-1800 m [36]. Above the treeline of the B. ermanii forest (2000 m), due to the harsh environment, the trees are sparse and dwarf forest [30].…”