Life-history constraints in grassland plant species: a growth-defence trade-off is the norm.
Plant growth can be limited by resource acquisition and defence against consumers, leading to contrasting trade-off possibilities. The competition-defence hypothesis posits a trade-off between competitive ability and defence against enemies (e.g. herbivores and pathogens). The growth-defence hypothesis suggests that strong competitors for nutrients are also defended against enemies, at a cost to growth rate. We tested these hypotheses using observations of 706 plant populations of over 500 species before and following identical fertilisation and fencing treatments at 39 grassland sites worldwide. Strong positive covariance in species responses to both treatments provided support for a growth-defence trade-off: populations that increased with the removal of nutrient limitation (poor competitors) also increased following removal of consumers. This result held globally across 4 years within plant life-history groups and within the majority of individual sites. Thus, a growth-defence trade-off appears to be the norm, and mechanisms maintaining grassland biodiversity may operate within this constraint.
Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, MN 55108, USA. elind@umn.edu
Eric M
EM
Lind
Elizabeth
E
Borer
Eric
E
Seabloom
Peter
P
Adler
Jonathan D
JD
Bakker
Dana M
DM
Blumenthal
Mick
M
Crawley
Kendi
K
Davies
Jennifer
J
Firn
Daniel S
DS
Gruner
W Stanley
WS
Harpole
Yann
Y
Hautier
Helmut
H
Hillebrand
Johannes
J
Knops
Brett
B
Melbourne
Brent
B
Mortensen
Anita C
AC
Risch
Martin
M
Schuetz
Carly
C
Stevens
Peter D
PD
Wragg
D000818:Animals; D017753:Ecosystem; D005308:Fertilizers; D060434:Herbivory; D008954:Models, Biological; D006109:Poaceae / Q000254:growth & development / Q000502:physiology*; D011157:Population Dynamics
D005308:Fertilizers