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Titel (primär) Local density effects on individual production are dynamic: insights from natural stands of a perennial savanna grass
Autor Zimmermann, J.; Higgins, S.I.; Grimm, V.; Hoffmann, J.; Linstädter, A.;
Journal / Serie Oecologia
Erscheinungsjahr 2015
Department OESA;
Band/Volume 178
Heft 4
Sprache englisch;
POF III (gesamt) T11;
Keywords Competition kernel; Grassland; Intraspecific competition; Neighbour abundance; Perennial grass
UFZ Querschnittsthemen RU5;
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.
ID 16034
dauerhafte UFZ-Verlinkung
Zimmermann, J., Higgins, S.I., Grimm, V., Hoffmann, J., Linstädter, A. (2015):
Local density effects on individual production are dynamic: insights from natural stands of a perennial savanna grass
Oecologia 178 (4), 1125 - 1135