Shrub encroachment affects tundra ecosystem properties through their living canopy rather than increased litter inputs

Aguirre, Daniela; Benhumea, Alejandro E.; McLaren, Jennie R.

doi:10.1016/j.soilbio.2020.108121

Cited by 31 publications

(17 citation statements)

References 58 publications

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“…Second, the shrub canopy can have a significant positive effect on understory herbaceous vegetation by improving the understory microenvironment, cover, biomass, and species diversity by improving the understory microenvironment (Howard et al, 2012). Furthermore, shrub patches have higher biomass and litter than their surrounding grassland patches, providing higher soil nutrient inputs (Aguirre et al, 2021). This study's total cover, biomass, Margalef, Pielou, and Shannon-Wiener indices of LT and ST shrub patches were lower than those of their meadow patches.…”

Section: Discussionmentioning

confidence: 99%

Effects of shrub encroachment on grassland community and soil nutrients among three typical shrubby grasslands in the alpine subhumid region of the Qinghai-Tibet Plateau, China

Liu

Chen

et al. 2022

Front. Ecol. Evol.

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IntroductionThe alpine meadows are distributed widely and play a vital role in ecosystem service functions on the Qinghai-Tibet Plateau (QTP). Under the combined effect of climate change and overgrazing, shrubs display an apparent expansion trend, leading to the shrinking of alpine meadows, and directly affecting the structure and function of grassland ecosystems. However, the effects of shrub encroachment on the plant community and soil nutrients of alpine grassland ecosystems still need to be clarified.MethodWe aimed to determine differences in vegetation characteristics and nutrient distribution along the soil profile between shrub patches and their adjacent grassland at three sites, which were three typical types of shrub-encroached grassland, including Spiraea alpina Pall. (SA), Lonicera tubuliflora Rehd. (LT), and Salix cupularis Rehd. (ST).ResultsThe results showed that shrub invasion changed the plant community structure of alpine grassland ecosystems, and shrub type was the critical factor driving this alteration. The expansion of the three shrubs reduced grassland species diversity. Shrub encroachment in SA positively impacted vegetation biomass but significantly decreased the soil organic content (SOC) and total nutrients. Shrub invasion in the ST had the most substantial impact on vegetation and soil, resulting in significantly lower nutrient content in shrubs than in grassland patches. The effect of LT was a significant reduction in vegetation biomass but no significant changes in biodiversity or soil nutrients. Grassland patches were more strongly correlated than shrub patches for SA and LT, while the opposite was true for ST. Vegetation characteristics were correlated least with soil nutrients for SA, while ST was most correlated, and LT was between them. Soil nutrients show more positive correlations with vegetation, enzyme activity, and microbial biomass in deeper soils (20–100 cm) than in shallow soils (0–20 cm). The deeper the soil layer is, the more significant the positive correlations in the shrub patches. Our findings indicated that shrubs play critical roles in the dynamics of vegetation patterns and soil environments for managing and sustainable utilization of shrubby alpine grasslands.

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Section: Discussionmentioning

confidence: 99%

Effects of shrub encroachment on grassland community and soil nutrients among three typical shrubby grasslands in the alpine subhumid region of the Qinghai-Tibet Plateau, China

Liu

Chen

et al. 2022

Front. Ecol. Evol.

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“…Second, the leaf nitrogen content of RL shrubs was also lower than that of SR shrubs, resulting in a significant difference in soil nitrogen (Damczyk et al, 2016;Yin et al, 2017). Correlation analysis and RDA also showed that the TN content had an extremely significant correlation with microbial community structure, microbial biomass, and multiple enzyme activities, and the differences in soil physical and chemical properties might have different effects on underground ecosystems (David et al, 2018;Aguirre et al, 2021). The results of soil fauna diversity were consistent with those of previous investigations conducted by He and Huang (HE et al, 2016;.…”

Section: Effect Of Shrub Islands On the Soil Biological Community And Chemical Characteristicsmentioning

confidence: 99%

“…Shrub islands feature dwarfed growth and island-like shrub flora distributed in meadow or tundra matrices (Benedict et al, 1984;Seastedt et al, 2001;Wang et al, 2007). This phenomenon can directly or indirectly affect the function of soil ecosystems (Blok et al, 2010;Ward et al, 2018;Aguirre et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

“…The upward invasion and area expansion of shrubs are the two most obvious effects of global climate change (Myers-Smith et al, 2018;Parker et al, 2021). The increase in temperature and subsequent input of more nutrients may be driving the increase in shrub islands at high elevations (Aguirre et al, 2021). Shrub islands are composed primarily of deciduous species, such as Betula pubescens and Sorbus rufopilosa (Jump et al, 2001;Wardle et al, 2012), but an increasing number of recent studies have reported that shrub islands composed of evergreen species, such as Rhododendron lapponicum, are also expanding (Zamin et al, 2014;Vowles et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

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Soil Biological Community and Chemical Characteristics of Evergreen and Deciduous Shrub Islands in an Alpine Shrub Meadow

Sha

Jin

Wang

et al. 2021

Preprint

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Aim Global change is driving shrub expansion in alpine and Arctic tundra, increasing the size and number of shrub islands. This phenomenon can directly affect the vegetation microclimate and indirectly affect biogeochemical cycling. However, it is unclear how shrub island formation, with a shift in dominant vegetation from graminoids to deciduous or evergreen shrub islands, affects the alpine biochemical cycling of carbon, nitrogen, phosphorus and decomposer diversity and activity. Methods Two dominant shrub species in the alpine shrub meadow in the eastern Tibetan Plateau were selected. Rhododendron lapponicum (RL) represents evergreen shrubs, and Sorbus rufopilosa (SR) represents deciduous shrubs. Soil fauna community diversity, soil microbial biomass, extracellular enzyme activity and enzyme stoichiometry of the organic soil layer (OL) and mineral soil layer (ML) were determined. Results Presence of shrub islands significantly affected nutrient cycling and microbial processes. Compared with the SR shrub island, the RL shrub island featured lower soil total nitrogen and microbial biomass carbon; lower total microbial phospholipid fatty acid, Gram-negative bacteria and total bacteria contents; and higher enzyme activities of β-glucosidase, cellobiohydrolase, β-N-acetylglucosaminidase, peroxidase and polyphenol oxidase. The OL response was greater than the ML response, especially in terms of enzyme activities. Conclusion Evergreen and deciduous shrub islands in an alpine shrub meadow had differences in soil biological communities and nutrient cycling, we suspect the OL was more sensitive than the ML to the shrub expansion in the alpine tundra.

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“…For example, shrub canopies intercept light and reduce photosynthetically‐active radiation at the understory (Mogashoa et al, 2020). Moreover, overstory shading directly affects temperature and water evaporation at the topsoil (Aguirre et al, 2020; Brantley & Young, 2009), which are key drivers of plant growth in alpine meadows (Sun, Zhou, Liu, et al, 2020). Due to the accumulation of labile organic matter from shrub leaf litter, shrub understories become ‘fertile islands’ which increases soil spatial heterogeneity (Tamura & Tharayil, 2014).…”

Section: Introductionmentioning

confidence: 99%

Shrub encroachment impaired the structure and functioning of alpine meadow communities on the Qinghai–Tibetan Plateau

et al. 2022

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Shrub encroachment has been rapidly occurring due to climate change, with profound ecological consequences for the alpine meadows of the Qinghai-Tibetan Plateau. Here, we conducted field surveys along a shrub coverage gradient to examine the effects of shrub encroachment on the structure and functioning of alpine meadows' plant communities. Our results showed that the overall coverage, density, aboveground biomass, species richness, and diversity of meadow community gradually declined with increasing levels of shrub encroachment, especially when shrub coverage exceeded 60%. Aboveground ecosystem multifunctionality also decreased along the shrub coverage gradient. With 90% shrub coverage, the relative importance value of the forbs functional group significantly increased while the Cyperaceae functional group showed the opposite trend: the originally dominant sedges Carex moorcroftii and Kobresia myosuroides were replaced by the forbs Androsace umbellate and Polygonum sparsipilosum. Additionally, shrub encroachment had a strong effect on nonrandom herb species extinction and colonization. At shrub coverages higher than 60%, there were 9 herb species absent and 18 new species colonizing-7 of which were only observed in meadows with 90% shrub coverage. Rare species and those with lower stature were more likely to go extinct, while taller and shadetolerant species tended to colonize areas with increasing shrub coverage. Overall, our results indicate that shrub encroachment negatively affects herbaceous community structure and functioning, which has important implications for the management of alpine meadows of the Qinghai-Tibetan Plateau under ongoing climate change.

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Shrub encroachment affects tundra ecosystem properties through their living canopy rather than increased litter inputs

Cited by 31 publications

References 58 publications

Effects of shrub encroachment on grassland community and soil nutrients among three typical shrubby grasslands in the alpine subhumid region of the Qinghai-Tibet Plateau, China

Effects of shrub encroachment on grassland community and soil nutrients among three typical shrubby grasslands in the alpine subhumid region of the Qinghai-Tibet Plateau, China

Soil Biological Community and Chemical Characteristics of Evergreen and Deciduous Shrub Islands in an Alpine Shrub Meadow

Shrub encroachment impaired the structure and functioning of alpine meadow communities on the Qinghai–Tibetan Plateau

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