Effects Of Spatial Heterogeneity Of Multiple Resources On Colonal Growth And Intraspecific Competion Of A Clonal Plant Iris Japonica Thunb

Vertical spatial heterogeneity in resource(light, water and nutrient) supply is common in natural habitats. Distributions of above-ground and below-ground resources in the same patches are always different in the same patches(?coincident patchiness‘) or different patches(?reciprocal patchiness‘). Clonal plants have multiple strategies on higher availability of resources in this complicated heterogeneous environment by forging and division of labor. C lonal plants are recognized to be more adaptable to heterogeneous environment than non-clonal plants. Numerous studies have tested the effects of heterogeneity of single resource(nutrient, water or light) on clonal growth of clonal plants. Iris japonica Thunb, a rhizome clonal plant, was widespread in open area of forest edge and under sparse forest with better light and water condition in C hina. It can become dominant population by clonal growth. This research focused on the clonal plant Iris japonica Thunb. which widespread under the forests to discuss effects of resource heterogeneity and intraspecific competition on clonal growth of Iris japonica Thunb.We conducted a greenhouse experiment to detect how spatial heterogeneity of resources affected colonal growth and intraspecific competition of iris japonica thumb..we grew one(no competition) or nine ramets(with intraspecific completion) of Iris japonica Thunb, in one homogeneous condition and four heterogeneous ones differing in patch size(large and small patch treatments) and type of heterogeneity(coincident patch and reciprocal patch). The total amount of light and water in the four heterogeneous treatments was as the same as that in the homogeneous medium light and water treatment. The growth of Iris japonica Thunb was lowest in coincident small patch under the competition conditions. Compared with the homogeneous treatment, the heterogeneous large patch treatment significantly improved the growth of Iris japonica Thunb under non-competition conditions. Under competition conditions, the growth of Iris japonica Thunb did not differ among the homogeneous and heterogeneous treatments. There was no significant difference among all kinds of heterogeneous small patch under non-competition conditions. The growth of Iris japonica Thunb was highest in low light high water large patch(LHL) under non-competition treatments. However, under competition treatment, the growth of Iris japonica Thunb was highest in high light high water patch(HH) while lowest in low light low water patch. The effects of heterogeneous resource on the growth of Iris japonica Thunb can be altered by intraspecific competition.We conducted another greenhouse experiment to detect how light, water and nutrient affected the growth of clonel plant Iris japonica Thunb. This research contained two small experiments. There were twelve treatments in total. One of them contained two light treatments(high light and low light) fully crossed with two water treatments(high water and low water) and two nutrient treatments(high nutrient and low nutrient). The other experiment contained two water treatments(high water and low water) crossed with four nutrient(high nutrient, medium nutrient, low nutrient and none nutrient) treatments. We found that the growth of Iris japonica Thunb was highest in high water medium nutrient treatment. Iris japonica Thunb grew fast to occupy advantageous environmental resources. While under water stress conditions, the lack of water would limit the growth of Iris japonica Thunb. The Iris japonica Thunb can‘t escape from inferior habitats by increasing rhizome length under water stress conditions.