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Abstract Patches of plants in drylands can arise when larger plants facilitate recruitment via ‘nurse‐plant’ effects. Simultaneously, plant–soil feedback processes can increase soil nutrients beneath shrubs leading to spatial patterns known as ‘islands of fertility’ that may also promote plant performance. These phenomena shape dryland plant communities; however, their comparative relative influences on plant density and diversity remain poorly quantified.Using reciprocal soil transplants among pairs of unvegetated interspaces and neighbouring shrubs in combination with cover treatments—open interspace, shaded interspace, intact shrub canopy and trimmed shrub canopy—this study aimed to disentangle the influences of shading from soil properties in native plant recruitment under the foundation species of shrubsLarrea tridentata andNeltuma glandulosain the Chihuahuan Desert, NM, USA.Seedling density varied significantly across years in response to interannual climate variability and was consistently higher underL. tridentatathanN. glandulosa. Cover treatments, soil provenance, shrub species and spatial factors (study blocks) significantly affected seedling density, species richness and community structure. Shading from intact shrubs or shade clothes had a stronger effect on density and richness than soil provenance or shrub species. Seedling density and richness were also higher in soil from beneath shrubs regardless of shrub species, location (native or transplanted locations) or time (study year) since initial translocation.The density of seedlings emerging from shaded interspace soil was initially similar to that observed under intact shrubs indicating the importance of shading by nurse plants for recruitment. However, the effect of shade‐cloth canopy surrogates on seedling density in interspaces switched from positive to negative by the third year of the study, likely due to seed bank depletion.Synthesis. The significant influence of shading highlights the role of environmental factors in shaping plant communities of this dryland system, while the evidence of seed depletion combined with the influence of plot location suggests a concurrent influence of stochastic community assembly processes. Understanding how these processes interact to shape spatial and temporal patterns of vegetation community assembly and potentially reinforce alternate ecological states remains an important focus in dryland ecosystems.
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Shading decreases and delays NDVI and flowering of prostrate Arctic shrubs
Increases in shrub growth and canopy cover are well documented community responses to climate warming in the Arctic. An important consequence of larger deciduous shrubs is shading of prostrate plant species, many of which are important sources of nectar and berries. Here, we present the impact of a shading experiment on two prostrate shrubs, Vaccinium vitis-idaea L. and Arctous alpina L., in northern Alaska over two growing seasons. We implemented three levels of shading (no shade, 40% shade, and 80% shade) in dry heath and moist acidic tundra. Plots were monitored for soil moisture content, surface temperature, normalized difference vegetation index (NDVI), and flowering. Shading was shown to, on average, lower surface temperature (0.7 °C to 5.3 °C) and increase soil moisture content (0.5% to 5.6%) in both communities. Both species- and plot-level NDVI values were delayed in timing of peak values (7 to 13 days) and decreased at the highest shading. Flower abundance of both species was lower in shaded plots and peak flowering was delayed (3 to 8 days) compared with controls. Changes in timing may result in phenological mismatches and can impact other trophic levels in the Arctic as both the flowers and resulting berries are important food sources for animals.
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- PAR ID:
- 10403923
- Date Published:
- Journal Name:
- Arctic Science
- Volume:
- 8
- Issue:
- 3
- ISSN:
- 2368-7460
- Page Range / eLocation ID:
- 967 to 978
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1139/as-2020-0043
