Study On The Tree Regeneration In Gaps In Pinus Tabulaeformis Forest In Zi Wuling Mountains

The forest gap is an indispensible driver in forest ecological variation. The gap provides adaptive habitat for seedlings and maintains the biodiversity. Thus, the gap was considered as an important condition for forest succession.Based on stands survey and compared analysis, the regeneration characteristics of pinus tabulaeformis forests was studied in ZhongWan in Zi Wu Mountains. the. Regeneration difference in gaps and forest was compared. The result as follow:1.The regeneration characteristics of pinus tabulaeformis forests in canopies and gaps are different :(1)The main regeneration trees specie are Quercus liaotungensis,Pinus tableformis,Ulmus davidiana under canopies,the number per ha is above 2000; The main regeneration species are Quercus liaotungensis,Pinus tableformis in gaps, the number is above 8000 N/hm2(.2)There are many shrubs under canopies, the major shrub are Smilax stans,Cotoneaster acutifolius,Cotoneaster multiflorus, the average density is above 3000 N/hm2;there are some shrubs in gaps, the major shrub are lespedeza bicolor,Ostriopsis, the density is above 2000 N/hm2.(3)The seedlings number that tree height is below 30cm are more in canopies than in gaps, the saplings number that tree height is above 50cm are more in gaps than canopies, there are 18000N/hm2. (4)there are more tree species in canopies than in gaps, but the important value of the major species in gaps is superior to that in canopies . (5) In conclusion, there are good regeneration in gaps in Zi Wu Mountains.2.The different tree species have different reaction to gaps in the process of regeneration. The major trees were classified into three ecological groups of species in canopies and gaps. The result showed that there are three tree species by strong positive regeneration response of gaps, only founded in gaps. So the average density and height of these seedling is advantage. There are six trees species by moderate regeneration response of gaps. There are thirteen trees species by non～significant regeneration response of gaps. They were not affected by gaps. 3.The regeneration characteristics of pinus tabulaeformis in canopies and gaps are different: (1) The important value of pinus tabulaeformis in gaps is far superior to in canopies. Variance analysis showed the height variance of pinus tabulaeformis have obvious difference between forest gaps and canopies, Pinus tabulaeformis is an important species for generation in gaps.(2)Seedlings and small saplings of Pinus tabulaeformis grow better in forest gaps. There are a few Pinus tabulaeformis saplings above 7 years under canopies. The number distribute of saplings above 1.0cm in diameter and above 50cm in height in gaps is superior to under canopies too. It showed the survival ability of pinus tabulaeformis seedlings and saplings in gaps is superior to under canopies with age increasing. The gaps provided good environment for the growth of pinus tabulaeformis saplings.(3) The gaps is benefit to species regeneration. pinus tabulaeformis have good regeneration potential under canopies, there are plenty of pinus tabulaeformis seedlings, but they have high mortality, the regeneration effect is not remarkable. There are more saplings in gaps than in canopies and the growths case is soupier to in canopies. The regeneration frequency is 96%.The regeneration effect is remarkable4.Relationship analyses showed it's an obvious and positive relationship between the pinus tabulaeformis seedlings numbers and illumination intensity, but negative relationship to vegetation coverage; The gap size is critical to the tree regeneration, the result showed that most seedlings were founded in gaps which size is from 200 m2to 250 m2...