| Broad-leaved Korean pine forests is zonal forest vegetation of upland in northeastern China,but it have degenerated to second forests and plantations at present because over exploitation and destruction,how to restore broad-leaved Korean pine forests is one problem that academia and production units pay general attention to.Effects of difference restoration approaches and management approaches(planting conifer and protecting broadleaf approach, Korean Pine plantation communities with broadleaf auxiliary species approach,Korean pine plantation approach and larch plantation approach) and their mechanism to community tree species composition,diameter classes distribution,Korean pine volume production,plant diversity and succession trend of second forests and plantations in forest region northeast China were studied by using sample plot with net check survey method,species richness and diversity index analysis method and layered numbers analysis method.Comprehensive and quantitative evaluate restoration effect,discuss the restoration optimization models of broad-leaved Korean pine forests in difference approaches in order to provide scientific basis for broad-leaved Korean pine forests restoration practice.Results showed that:(1)Planting conifer and protecting broadleaf approachUpper layer canopy thinning had great effects on tree species composition,diameter classes distribution,Korean pine volume productivity,plant diversity and succession trend of planting conifer and protecting broadleaf communities.Importance value of Korean pine increased gradually(0.300～0.708) along with the decreasing of upper layer canopy density preserving(0.8-contrast,0.6,0.4,0.2,0.0-clear cutting) and the predominant position of Korean pine increased gradually;proportion of median diameter classes Korean pine increased(0.00%～56.17%),proportion of smaller diameter classes Korean pine decreased(100.00%～35.83%);community volume showed decreasing trend changes(239.3778 m3·hm-2～125.7011 m3·hm-2) and change range was great(0.90 times),Korean pine volume productivity showed increasing trend changes(0.1522m3·hm-2·a-1～2.8594m3·hm-2·a-1) and change range was greater(17.79 times);community species richness were 52,49,52,44 and 47 respectively,showed a decreasing trend as a whole,species diversities were 2.7329,2.4960, 2.6780,2.4382and 1.5833 in turn,all showed a little decreasing(2.01%～10.78%) except clear cutting had a greater decrease(42.07%);all the communities showed a succession trend to broad-leaved and conifer Korean pine forests,but median and low canopy density communities had better succession trend.(2) Plantation communities with broadleaf auxiliary species approachUpper layer canopy thinning had great effects on tree species composition,diameter classes distribution,Korean pine volume productivity,plant diversity and succession trend of plantation communities with broadleaf auxiliary species.Importance value of Korean pine of plantation communities with broadleaf auxiliary increased gradually(0.499～1.000,0.461～0.628) of more times(2～3 times clear cutting broadleaves) or one time upper layer canopy thinning along with upper layer canopy thinning intensity increased(contrast,median thinning,strong thinning) and the predominant position of Korean pine in communities increased gradually;all the larger diameter classes Korean pine present in strong thinning communities(54.05%, 1.65%),proportion of smaller diameter classes Korean pine all decreased(74.99%～2.70%, 75.15%～43.80%);community volumes of more times upper layer canopy thinning were 234.3483,276.7883 and 253.3167 m3·hm-2 respectively,Korean pine volume productivity were 1.2692,3.1271 and 5.3603 m3·hm-2·a-1 in turn,median thinning and strong thinning communities volume increases 0.18 and 0.08 times respectively than contrast,Korean pine volume productivity increased 1.46 and 3.22 times;community volumes of one time upper layer canopy thinning were 1.7050,2.3136 and 3.3514 m3·hm-2·a-1 respectively,Korean pine volume productivity were 1.2692,3.1271 and 5.3603 m3·hm-2·a-1 in turn,median thinning and strong thinning communities volume increases 1.35 and 2.83 times respectively than contrast,Korean pine volume productivity increased 0.36 and 0.97 times;all median thinning showed greatest community richness(43,31),strong thinning and median thinning showed greatest species diversities(1.9739 or 2.0683);more times upper layer canopy thinning showed a development succession trend as a whole,one time upper layer canopy thinning showed a degradation succession trend as a whole.(3) Korean pine plantation approachTending thinning had great effects on tree species composition,diameter classes distribution,Korean pine volume productivity,plant diversity and succession trend of Korean pine plantation communities.The predominant position of Korean pine in communities increased along with upper layer canopy thinning intensity increased(contrast,weak thinning, median thinning,strong thinning),Importance value of Korean pine in all thinning communities(all were 1.000) increased 15.70%than contrast community(0.843);proportion of larger diameter classes Korean pine increased(24.72%～85.00%),proportion of median diameter classes Korean pine decreased(75.28%～15.00%),no smaller diameter classes Korean pine appeared in all thinning communities;community volumes were 447.8580,386.7443, 446.5654 and 458.4742 m3·hm-2 in turn,Korean pine volume productivity were 7.8258, 7.8827,9.1136 and 9.3566 m3·hm-2·a-1 in turn,weak thinning communities volume decreased greatly than contrast(13.65%),median thinning and strong thinning communities volume were similar to contrast(0.29%～2.37%),Korean pine volume productivity of weak thinning communities similar to contrast(0.73%),but median thinning and strong thinning communities increased than contrast(16.46%～19.50%);community species richness were 18, 26,27 and 33 respectively,showed a decreasing trend(44.44%～83.33%),species diversities were 0.5823,1.0479,0.9197 and 1.2295 in turn,showed a decreasing trend(57.94%～111.15%) as a whole;thinning communities showed a succession trend to broad-leaved and conifer Korean pine forests as a whole,but the contrast communities showed a degradation succession trend as a whole,not favorable to the development of broad-leaved and conifer Korean pine forests.(4) larch plantation approachDifferent slope position had great effects on tree species composition,diameter classes distribution,Korean pine volume productivity,plant diversity and succession trend of larch plantation communities.From low to up slope environmental gradients,larch occupied the predominant position in all communities(0.376～0.461),Korean pine occupied the second predominant position and showed a gradual increasing trend(0.279～0.402),broadleaf trees occupied a certain proportion in communities(0.186～0.290),so the community composition of larch plantation showed a obvious naturalization trend,proportion of larger diameter classes larch decreased(29.79%～11.32%),proportion of median diameter classes larch increased(68.08%～88.68%),a little smaller diameter classes larch distribute only in low slope positions(2.13%),proportion of median diameter classes broadleaf trees increased(18.18%～58.34%),proportion of median diameter classes broadleaf trees decreased(81.82%～41.66%),no larger diameter classes broadleaf trees,proportion of median diameter classes Korean pine increased(7.68%～15.00%),proportion of median diameter classes Korean pine decreased(92.32%～85.00%),no larger diameter classes Korean pine, although larch plantation showed the naturalization trend,but broadleaf trees and Korean pine below larch canopy all were median and smaller diameter classes trees,it needs artificial inducement in order to promote Korean pine and broadleaf trees growth;community volumes showed a decreased trend(306.0200 m3·hm-2～262.0104 m3·hm-2),had little change range(0.16 times),larch volume decreased by fluctuating model(282.5400 m3·hm-2～208.8335 m3·hm-2),had little change range(0.35 times),broadleaf trees volume changed by fluctuating model(7.6653 m3·hm-2～8.8176 m3·hm-2),had little change range(0.15 times),Korean pine volume and volume productivity increased by fluctuating model(15.6310 m3·hm-2～35.0700 m3·hm-2 and 0.4466m3·hm-2·a-1～1.0020m3·hm-2·a-1),had greater change range(1.24 times), although larch plantation community showed the naturalization characteristics,but it need to increase broadleaf trees and Korean pine volume below canopy ceaselessly in order to form broad-leaved and conifer Korean pine forests;community species richness were 48,48 and 44 in turn,showed a invariable earlier then decreasing trend,had little change range(9.09%), species diversities were 1.3867,2.2183 and 1.6970 in turn,showed a single peak distribution type,had greater change range(22.38%～59.97%),so median slope position were more favor of maintain community species diversity;all communities showed a development succession trend to broad-leaved and conifer forests as a whole.(5) Selection of optimization modelsOn the basis of comprehensive evaluating effects of planting conifer and protecting broadleaf approach,plantation communities with broadleaf auxiliary species approach,Korean pine plantation approach and larch plantation approach on the restoration of broad-leaved and conifer Korean pine forests,selected the optimization models which had best restoration effects by different management and using different stand condition in different restoration approaches: they were more favor of restoration of broad-leaved and conifer Korean pine forests which low canopy density model by increasing cut intensity in planting conifer and protecting broadleaf approach,strong thinning model by more times clear cutting upper layer canopy broadleaves in plantation communities with broadleaf auxiliary species approach,median tending thinning models in Korean pine plantation approach and median slope position model in larch plantation approach respectively.
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