Effects Of Reciprocal Patchiness And Coincident Patchiness Of Resources On The Cloning Features And Clonal Integration Of Iris Japonica Thunb

In natural habitats, essential resources for plant survival, growth and reproduction, such as light and water, are often patchily distributed in horizontal spatial. Two common and obvious spatial heterogeneity patterns that affecting the growth of clonal plants are resource vertical space pattern of positive correlation and negative correlation. The positive association between different resources is called coincident patchiness. The negative association between different resources is called reciprocal patchiness. Numerous studies have tested the effects of heterogeneity of single resource(nutrient, water or light) on clonal growth of clonal plants. So far, few studies has been done on the benefits of clonal integration under either reciprocal or coincident patchiness of above-ground and below-ground resources. Iris japonica Thunb, is a rhizome clonal plant widespread in open area of forest edge and under sparse forest with better light and water condition in China. 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 fragmentation on clonal growth of Iris japonica Thunb.We conducted a field investigation experiment to examine how vertical spatial heterogeneity in resource(light and water) affected the clonal growth of Iris japonica and Reineckea carnea. According to the light intensity and soil water content of the natural habitats of Iris japonica and Reineckea carnea through repeated measurement, we selected six types of sample area: high light low water, high light middle water, middle light middle water, middle light low water, low water high water, low light middle water. The results showed that the clonal architecture(rhizome length), population density(No.of remat)and clonal growth of Iris japonica and Reineckea carnea changed with vertical heterogeneous resources. Internode-lengths of Iris japonica were larger in high water habitats, while internode-lengths of Reineckea carnea were largest in high light low water habitats. Two-way ANOVA analysis indicate that water type have significant impact on all measurement index of Iris japonica(P<0.05), while light type have significant impact on all measurement index of Reineckea carnea(P<0.05). The effects of resource vertical heterogeneity on clonal plants varied among species.We conducted a greenhouse experiment to detect how spatial heterogeneity of resource(reciprocal patchiness and coincident patchiness)and severment the spacer between the proximal ramet and the distal ramet affected the clonal growth of Iris japonica. Three-way ANOVAs showed that patch contrast(high-low,high-moderate vs. moderate-low)and patchiness type(coincident patch vs. reciprocal patch)have significant impact on the tolal biomass of Iris japonica. Low level of resources in contrast have negative effect on the clonal growth of Iris japonica. Under the same patch contrast, coincident patchiness is more suitable for the growth of Iris japonica. The clonal integration of clonal fragment is much more significant in coincident patchiness. The benefiting ramets are both the the proximal ramet and the distal ramet When patch contrast is high(high-low) in coincident patchiness, while the proximal ramets benefit when patch contrast is low. In reciprocal patch, the benefiting ramets are the proximal ramets when patch contrast is high and the benefiting ramets are the distal ramets when patch contrast is low. Patch contrast and patchiness type changed the effect of clonal integration on the clonal growth of Iris japonica.