The Model Construction And The Effectiveness Evaluation By Near-Natural Management Of Pinus Tabulaeformis Plantation In Central Mountainous Area Of Shandong Province

Pinus tabulaeformis is one of the species for artificial afforestation in barren mountainous areas of north China with the evergreen landscape,and they could be with better resistance to adapt to the biotic and abiotic stresses.However,the site conditions of the trees in mountainous areas of Shandong province are generally barren,as well the pine stand was of excessive density and growth dysplasia which could lead to lower ecological and economic benefits of the pine forests.Moreover,it‘s difficult to carry out the long-term management on the pine mountains stands.Therefore,a long-term tending model of pine plantation was established based on the growth rules of the Pinus,the rhythms of forest community succession,and the development stage of common forest population.The near-natural management as the major theory guidance was applied to forest tending processing.The field experiment was located at the Forest Farms of Culaishan.Variaties of forest stands such as pure forest of P.tabularis suffering to the tending managements were treated as the testing materials.The growth properties like height?H?,diameter of canopy,diameter at breast-high?DBH?etc.of the trees,also the plants species and quantities in the understory and physicochemical properties in the soil were tested through the field investigation and lab analysis in our experiment,and the results showed as follows:1.Based on the diagnosis of forest facies and the analysis of suitable site and tree,the growth and development law and the community succession law of pinus tabulaeformis plantation were studied.The near-natural management model of multi-function pine forest was built up in our study,and the technical treatment for community succession in various stages of the pine forest were put forward.Simultaneously,the main factors on target tree operation in the near-natural processing were established.The phased measures specified to various stand characteristics of pine plantation were adapted according to the classification of near-natural management stages.The results of the phased tending processing indicated that:at the stand formation stage?H?6 m,DBH?5 cm?,the main jobs were to increase the survival rate of seedlings for barren hill afforestation and to promote the transmission.At the stages of competition differentiation that trees with rapid growth?6 m<H?10 m,5 cm<DBH?12 cm?,and the main task was to thinning the trees.It was the main content to promote the development of target trees and other trees regeneration under the selection stage?10 m<H?18 m,12 cm<DBH?22 cm?.At close-to-nature forest phases?18 m<H?26 m,22 cm<DBH?40 cm?,the tending measures preferred to cultivate the large diameter of timbers and to decrease the stand density by the selective cuttings.At naturalness permanent stage?H?20 m,DBH?30 cm?,the main tending measures were the principal-felling and regeneration in the selection system.2.The near-natural management scheme of artificial plantation was designed while taking example of the pure forest of P.tabulaeformis by the evaluation of suitable trees and the diagnosis of the goal forests in the practical stands.Hence,the multifunctional tending managements were implemented and the effects of reforests investigated.?1?The measures of near-natural tending processing were carried out in a pure stand of P.tabulaeformis at Culaishan forestry station based on the actual investigation results.The investigated results indicated that this stand entered the later period of quality selection stage,whereas the major features were the intense individual competition and rapid growth at the overstory of the stand trees.Hence,the current tending objective was to structure an initially uneven aged mixed tiered forest,while the medium and long-term managed goals could convert the stably even-aged pure pine forest to the continuous forest during the operating period of 5²0 years.The target trees management was the core tending operation in the design scheme.Firstly,four tree types were divided and then marked including goal trees,auxiliary trees,disturbance trees and the others.Secondly,the target DBH of the goal trees in existing stand and update layer were setted as 30 cm and 35 cm,respectively;the reserved number of goal trees was of 75⁹0 in per hectare of land during the managing period of10²0 years.Thirdly,removing the disturbance woods periodically,and the cutting intensity was of 15²0%by 5 years of tending operation,of 10²0%by 10 years and of 5¹0%by 20years when suffered to the tending management,respectively.Meanwhile,the trunk height was not less than 2/5²/3 of the tree height after pruning,and the retained density of young woods were of 300⁴50 trees·hm^-2 after the singling thinning.The method of scale ripple was arranged to the trees aiming to strengthen the growth,development and fructifications of the target woods,also followed with replanting to promote the artificial regeneration.Fourthly,removing the shrubs and herbs partly of the sapling at the understory with a coverage ratio of20%.Finally,recycling the available woods and cleaning up the leftcovers such as the finely branches and chips after trees logging processing.?2?The near-natural management experiments were carried out at three forestry station of Culaishan,with thinning possesses time of 2 years.The results revealed that the tending operation could benefit to the stand growth,enrich the undergrowth diversity,as well improve the soil quality in different stand conditions.The effects of thinning stand could promote the seedling growth compared to the controlled treatment?CK?,the main height,DBH and diameter of canopy increased by 5.69%,7.95%and 2.75%,respectively.Similarly,the mean annual diameter growth of residual trees height,DBH and diameter of canopy also improved by 66.67%,26.15%and 300.0%when suffered to near-natural processing.The intermediate cutting changed the canopy gap,led to a decrease in crown closure.On the contrary,it caused an increase in plant species of shrub layer especially for the light-loving plants like Platycladus orientalis,while there was no significant impacts on plant quantities.Consistently,it could contribute to the herbs diversity,which along with improvements of diversity indexes like Simpson,Shannon-wiener and Gleason,and the promoted ratios of 1.93%,10.43%and4.67%in pure pine stand,respectively.At the same time,the important values of Digitaria sanguinalis,Spodiopogon sibiricus and Carex rigescens elevated.Moreover,the tending measurement could improve soil pH by 3.45%,and decreased bulk density by 7.89%.As well,it had a potential to accelerate the nutrient metabolism for the increasing enzyme activities of catalase,phosphatase,sucrase and urease,which increased by 25.56%,4.99%,5.44%and6.98%,respectively.