M. Moreno-de las Heras
Seed-bank structure and plant-recruitment conditions regulate the dynamics of a grassland-shrubland Chihuahuan ecotone
Moreno-de las Heras, M.; Turnbull, L.; Wainwright, J.
Professor John Wainwright firstname.lastname@example.org
Dr Laura Turnbull-Lloyd email@example.com
Large areas of desert grasslands in southwestern USA have shifted to sparse shrublands dominated by drought-tolerant woody species over the last 150 years, accompanied by accelerated soil erosion. An important step towards the understanding of patterns in species dominance and vegetation change at desert grassland-shrubland transitions is the study of environmental limitations imposed by the shrub-encroachment phenomenon on plant establishment. Here, we analyze the structure of soil seed-banks, environmental limitations for seed germination (i.e., soil-water availability and temperature) and simulated seedling emergence and early establishment of dominant species (black grama, Bouteloua eriopoda, and creosotebush, Larrea tridentata) across a Chihuahuan grassland-shrubland ecotone (Sevilleta National Wildlife Refuge, New Mexico, USA). Average viable seed density in soils across the ecotone is generally low (200-400 seeds m−2), although is largely concentrated in densely vegetated areas (with peaks up to 800-1200 seeds m−2 in vegetated patches). Species composition in the seed-bank is strongly affected by shrub encroachment, with seed densities of grass species sharply decreasing in shrub-dominated sites. Environmental conditions for seed germination and seedling emergence are synchronized with the summer monsoon. Soil-moisture conditions for seedling establishment of B. eriopoda take place with a recurrence interval ranging between 5 and 8 years for grassland and shrubland sites, respectively, and are favored by strong monsoonal precipitation. Limited L. tridentata seed dispersal and a narrow range of rainfall conditions for early seedling establishment (50-100 mm for 5-6 consecutive weeks) constrain shrub-recruitment pulses to localized and episodic decadal events (9-25 years recurrence intervals) generally associated with late-summer rainfall. Re-establishment of B. eriopoda in areas now dominated by L. tridentata is strongly limited by the lack of seeds and decreased plant-available soil moisture for seedling establishment.
Moreno-de las Heras, M., Turnbull, L., & Wainwright, J. (2016). Seed-bank structure and plant-recruitment conditions regulate the dynamics of a grassland-shrubland Chihuahuan ecotone. Ecology, 97(9), 2303-2318. https://doi.org/10.1002/ecy.1446
|Journal Article Type||Article|
|Acceptance Date||Mar 4, 2016|
|Online Publication Date||Sep 1, 2016|
|Publication Date||Sep 1, 2016|
|Deposit Date||Mar 11, 2016|
|Publicly Available Date||Mar 15, 2016|
|Publisher||Ecological Society of America|
|Peer Reviewed||Peer Reviewed|
Accepted Journal Article
Copyright by the Ecological Society of America
Published Journal Article
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