Effects Of Spatial Patterns On Clonal Integration Of Phyllostachys Bissetii Under Heterogeneous Light

Environmental heterogeneity is ubiquitous and it is particularly evident in cities.Bamboo,which is important garden materials for the Chinese traditional gardens,faces a variety of complex and diverse living environments.Bamboo is a typical rhizomes clonal plant which has unique clonal integration to clonal plants.Clonal integration causes matter tanslocation between the connected ramets to provide nutrients for the ramets which are in the heterogeneous environment and it can enhance their fitness to heterogeneous.Clonal integration affects the rhizosphere soil environment of the neighbouring ramets,which also affects the rhizosphere ecology processes such as soil microbial community structure,soil enzymes activities and organic matter transformation.Some studies now focus on whether clonal integration affects the rhizosphere ecologiy processes.The clonal integration may be affected by the factors such as clonal integration direction,spatial scale,and clone fragment size and it needs further exploration.In this study,the clonal plant Phyllostachys bissetii was selected as the experimental material,and the in-situ experiment was used to simulate the uneven illumination and the lack of illumination in the urban environment for shading.Through three group of controlled experiments,the spatial pattern characteristics of clonal integration directionality,spatial scale and clone size were taken to study the transformation process of rhizosphere soil organic matter,and to understand the intrinsic mechanism of carbon and nitrogen cycling in the rhizosphere soil of clonal plant under clonal integration.The effects of spatial traits of clonal integration directional,spatial scale and clone fragment size on the resource transmission pattern among the Phyllostachys bissetii ramets were analyzed.The main conclusions are as follows:（1）In the transportation direction experiment,total organic carbon（TOC）,dissolved organic carbon（DOC）,dissolved organic nitrogen（DON）and soil inorganic nitrogen（NH₄⁺-N and NO₃^–-N）content in the rhizosphere soil of offspring ramets with connected rhizomes were significantly higher than those with severed rhizome in acropetal treatment.The activities of urease,polyphenol oxidase（POXase）,N-acetyl-β-D-Glucosaminidase（NAGase）were significantly enhanced.Further,clonal integration had a significant effect on C and N availability,and microbial processes in the rhizosphere soil of neighbouring ramets.In basipetal treatment,clonal integration did not show a significant effect on C availability in the rhizosphere soil of mother ramets,but microbial processes along with soil enzyme activities were altered accordingly.The difference of clonal integration direction resulted in different changes in the C availability of the rhizosphere,and thus had different effects on the microbial processes such as the rhizosphere soil enzymes activities.（2）In the spatial scale experiment,with the increase of spatial scale,the contents of TOC,TN,DOC,DON,MBC,MBN,NH₄⁺-N and NAGase,POXase and Urease activities in the rhizomes of rhizomes were observed.The trend of increasing first and then decreasing.The content of NO₃^–-N increases first,then decreases and then rises again.With the increase of spatial scale,the rhizosphere nitrogen transformation process of cut rhizomes was changed.The contents of TOC,TN,DOC,DON,NH₄⁺-N and NAGase and Urease showed a cubic function.First decrease,then increase and then decrease again,NO₃^–-N content is opposite;MBC and MBN content decrease continuously with spatial scale,POXase activity and mineralization rate(N_min),nitrification rate(N_nitri)show first increase after lowering.The spatial scale difference produced a very different change in the C and N availabilities of the rhizosphere with rhizomes connected or severed.（3）In the size of the clonal fragment experiment,the content of TOC and MBN in rhizosphere with connected rhizomes increased with the size increase of clonal fragments.The DOC,DON,NO₃^–-N content and POXase activity increased first and then decreased with the size increase of clonal fragments.The TOC,DOC,DON,MBC contents and Urease activity in the rhizosphere with severed rhizomes increased with the size increase of clonal fragments.The TN,NH₄⁺-N and NO₃^–-N contents and NAGase activity decreased first and then increased.The pattern of resource transfer is affected by the size of the clonal fragment.In summary,the difference of clonal integration direction results in different changes in the C availability in the rhizosphere of mother ramets and offspring ramets,and thus has different effects on the microbial processes such as the rhizosphere soil enzyme activity,which means that there is a directional difference in nutrient transportation between clonal plant ramets.Clonal integration in the some spatial scale can promote the rhizosphere nitrogen transformation process with connected rhizomes,but it is affected by the distance and loss of matter translocation.The clonal fragments of different sizes are affected by the number and age of the ramets.The quality and transmission rate of the resources that can be influenced when they are used as the―source‖of nutrients,and they are also limited by energy consumption and spatial scale.Therefore,the clonal integration directiona,spatial scale and clonal fragment size will affect the pattern of resource translocation in clonal plants.