A trade-off between guerrilla and phalanx growth forms in Leymus secalinus under different nutrient supplies.
OBJECTIVE
A phalanx growth form enables clonal plants to make better use of resource-rich patches, whereas a guerrilla growth form provides them with opportunities to escape from resource-poor sites. Leymus secalinus produces both spreading (guerrilla form) and clumping ramets (phalanx form). Here, the hypothesis that a trade-off between the two growth forms in L. secalinus exists under different resource levels is tested.


METHODS
Ramets of L. secalinus were grown under three levels of nutrient supply.


RESULTS
With increasing nutrient supply, the proportion of clumping ramets (in total number of ramets) increased, whereas that of spreading ramets decreased. With increasing nutrient supply, the number of buds increased, whereas biomass per bud decreased. A trade-off between bud number and size further supports the above hypothesis because larger buds were more likely to develop into spreading ramets, and smaller buds into clumping ramets. Mean spacer length between spreading ramets was significantly smaller under the high than under the medium nutrient supply.


CONCLUSIONS
The results suggest that a trade-off between the two growth forms in L. secalinus exists under different nutrient supplies. Such a trade-off together with plasticity in spacer morphology may enable L. secalinus to make better use of small-scale heterogeneity in resource supply.
Ye
Xue-Hua
XH
Laboratory of Quantitative Vegetation Ecology, Institute of Botany, The Chinese Academy of Sciences, 20 Nanxincun, Fragrant Hills, Haidian District, Beijing 100093, China.
Yu
Fei-Hai
FH
Dong
Ming
M