| Litter production is one of the main form of forest ecosystem material return, material circulation and energy flow in key ecosystem plays an important role in the process. However, forest litter by forest structure, seasonal change of yield and its components and a variety of terrain and environment factors. Forest gap is the forest natural regeneration of main power, its produce and dissolution process is often accompanied by obvious environmental change with time and space. Spatial and temporal variations of these Windows driver gaps will inevitably affect the forest litter from forest undergrowth window center to the distribution pattern of space and time and the composition distribution pattern, but the lack of necessary attention. Alpine forest in western sichuan is located in the upper stream of Yangtze river water conservation, biodiversity conservation, regulating regional climate is of great significance, but affected by frequent geological disasters and low temperature, forest soil level development limited, litter to maintain forest "exploit" ability as well as the system structure and function is more important. Therefore, at an altitude of 3586m and 2982m typical western sichuan alpine forest as the research object, in August 2015-November litter fall peak dynamic investigated along the window center, Gaps edge undergrowth and dynamic distribution pattern of litter production and its components, in order to understand alpine forest gaps update of litter drive in the process of circulation key ecological processes such as to provide basic data.During the study period, at an altitude of 3586m and 2982m alpine forest litter fall amount of 1303.55 kg/hm2 and 494.34 kg/hm2, and litter production center to forests along the forest gap showed increasing trend. Alpine forest litter fall amount at an altitude of 3586m in the window, forests and forests are evident in the three types of sample area alpine forest at an altitude of 2982m. Relative to other time, at an altitude of 3586m alpine forest to litter production in September, the largest up to 711.09 kg/hm2; And alpine forest at an altitude of 2982 m to litter production in October, the largest up to 448.66 kg/hm2;Relative to other components, scraping leaves, the largest proportion of alpine forest to an altitude of 3586m litter production in September, the largest of 647 kg/hm2, at an altitude of 2982m alpine forest to litter production in October, the biggest of 433.72 kg/hm2, litter leaf production along the gaps center to understorey forests all showed increasing trend. Proportion of litter branch is the second largest, except litter leaf alpine forest to an altitude of 3586m of litter collected on November 18, the highest yield, up to 139.74 kg/hm2, at an altitude of 2982m of alpine forest litter the highest yield in August,32.57 kg/hm2.Epiphytes output is less, at an altitude of 3586m and 2982m the biggest production in October reached 4.47 kg/hm2 and 0.53 kg/hm2, at an altitude of 3586m in the alpine forests, litter production along the window gaps center to understorey forests showed increasing trend, and at an altitude of 2982m alpine forest have no obvious regularity changes. Flowers and fruit of litter production at an altitude of 3586m and 2982m are rarely in the alpine forests, also under the influence of forest gap no obvious regularity.At an altitude of 2982m of alpine forest, relative to other layers, trees accounts for most of the column. Shrubs litter content presented as time increases with the increasing trend and tree litter content increased with time, a basic trend to increase after the decrease, while the mixed litter did not change significantly over time. Shrubs litter and other hybrid litter production reached the maximum in November were 100.47 kg/hm2 and 35.17 kg/hm2, tree litter production reached maximum 181.02 kg/hm2 in October. In different forest gap position, Joe, shrub and mixed litter content are presented along the forest undergrowth window center to the increasing trend.At an altitude of 3586m in the alpine forest, shrubs, litter content basic presents as time increases with the increasing trend, and the trees and mixed litter content increase over time and present the basic first increased after decreased trend. Shrubs litter the maximum output in November 221.21 kg/hm2, tree litter the maximum output is in September 255.95 kg/hm2, other mixed litter production in the maximum in October reaches 166.73 kg/hm2, in different forest gap position, shrub litter content along the forest gap center to forests showed increased after decreased trend, then tree litter content presented along the forest undergrowth window center to the increasing trend. Mixed litter content, there is no clear trend.Different species distribution and the peak period of litter content is different, belong to the shrub tree species, most distribution takes to window and forest edge position, belong to the arbor tree species, mostly forests margins and the location of the forests. Shrub tree species and tree litter of broad leaved tree species of common early conifer tree litter peak in August to September. Peak and conifer tree litter common in October and November.To sum up, the forest undergrowth window center to 3586m alpine forest litter fall amount all showed increasing trend, litter, Branch litter, epiphytes and other mixed litter production also presents the increasing trend, flower and fruit yield no significant trend, shrub showing a decrease trend and basic trees showed increasing trend, other mixed litter has no obvious trend of different species of basic presents the increasing trend. Along the forest undergrowth window center to 2982m alpine forest lifter fall amount also presents the increasing trend, litter and other mixed litter basic presents increasing trend, the trend of the other components is not obvious, shrubs and other mixed litter presents the increasing trend, arbor, presents the trend of increased after decreased first, different species also presents the increasing trend. Visible, Gaps significantly affect the cold window of space-time distribution pattern of forest litter and its components, the alpine forest litter return for recognizing key ecological processes and their associated provides certain theoretical basis. |
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