Universität zu Köln

Zimmermann, Julia, Higgins, Steven I., Grimm, Volker, Hoffmann, John and Linstaedter, Anja (2015). Local density effects on individual production are dynamic: insights from natural stands of a perennial savanna grass. Oecologia, 178 (4). S. 1125 - 1136. NEW YORK: SPRINGER. ISSN 1432-1939

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Abstract

Perennial grasses are a dominant component of grasslands, and provide important ecosystem services. However, most knowledge of grasslands' functioning and production comes from plot-level studies, and drivers of individual-level production remain poorly explored. Extrapolation from existing experiments is hampered by the fact that these are mostly concentrated on even-aged cohorts, and/or on the early stages of a plant's life cycle. Here we explored how local density regulates individual production in mono-specific natural grassland, focusing on adult individuals of a perennial savanna grass (Stipagrostis uniplumis). We found individual production to increase with individuals' size, but to decrease with neighbour abundance. A metric of neighbour abundance that considered size was superior to a metric based solely on the number of individuals. This finding is particularly important for studying competitive effects in natural populations, where plants are normally not even-sized. The inferred competition kernel, i.e. the function describing how competitive strength varies with spatial distance from a target plant, was hump-shaped, indicating strongest intraspecific competition at intermediate distances (10-30 cm). The spatial signature of competitive effects changed with time since fire; peak effects moved successively away from the target plant. Our results suggest that inferred competition kernels of long-lived plant populations may have shapes that differ from exponential or sigmoidal decreases. More generally, results underline that competition among neighbouring plants is dynamic. Studies that address density-dependent and density-independent (fire-related) population dynamics of perennial grasses in their fire-prone environment may thus shed new light on the functioning and production of grasslands.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Zimmermann, Julia UNSPECIFIED UNSPECIFIED UNSPECIFIED Higgins, Steven I. UNSPECIFIED UNSPECIFIED UNSPECIFIED Grimm, Volker UNSPECIFIED UNSPECIFIED UNSPECIFIED Hoffmann, John UNSPECIFIED UNSPECIFIED UNSPECIFIED Linstaedter, Anja UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-397854
DOI:	10.1007/s00442-015-3291-9
Journal or Publication Title:	Oecologia
Volume:	178
Number:	4
Page Range:	S. 1125 - 1136
Date:	2015
Publisher:	SPRINGER
Place of Publication:	NEW YORK
ISSN:	1432-1939
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language BELOW-GROUND ZONE; PLANT INTERACTIONS; COMPETITION; POPULATION; FIRE; FACILITATION; INTENSITY; FOREST; GROWTH; VEGETATION Multiple languages Ecology Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/39785