Evaluation On Stand Quality And Ecological Function Of Main Coniferous Timber Stands In Hubei Province

Forest ecosystem is an important part of terrestrial ecosystem,which has multiple ecological regulation and service functions such as wood production,ecological balance maintenance and species diversity protection.China has a large forest area and a rapid development of plantation,but there are also many stand quality and ecological function problems.Under the rigid constraint of forest area,the strategic focus of forestry is to improve the stand quality.Therefore,accurate and effective evaluation of stand quality has attracted much attention.Hubei province is located at the core of the Yangtze River Economic Belt.The plantation is mainly composed of conifer tree species such as Cunninghamia lanceolata,Pinus elliottii,Larix kaempferi,Pinus massoniana and so on,with a large area and plays an important role in local forestry construction and economic development.In this study,the main coniferous plantation(Cunninghamia lanceolata,Pinus elliottii,Larix kaempferi)in Hubei Province were taken as the research object,and the forest quality evaluation and ecological function evaluation were carried out used the survey data of forest resource planning and design in 2019(76518 sub-compartment were screened)and the data of sample-plots surveyed in 2016～2017(269 plots were screened),used principal component analysis,comprehensive scoring method,area weighting method,ecological function index and other methods.The following research results were obtained:(1)Combined with the actual situation of main coniferous forest in the study area,three criteria and 12 indexes were selected for stand quality evaluation:stand productivity(including 4 indexes such as DBH index,H index,stand volume index and stand area),site quality(including 3 indexes such as soil type,soil thickness and altitude),stand stability(including 5 indexes such as age group,canopy density,suitable area,total vegetation coverage and community structure).The index weight of each tree species was slightly different,but both stand productivity and stand stability had a greater impact on stand quality,as well as the DBH index,H index,stand volume index and age group in the index layer had a greater impact on stand quality.(2)The quality scores of the compartments ranged from 0.1241 to 0.7645,generally following a normal distribution,and the quality levels could be classified into three categories:poor,medium,and excellent;most of the main coniferous timber forests are at a moderate level,with 63235 sub-compartment and 258124.53 hm2 of area,respectively,accounting for 82.64%and 80.44%respectively.The ecological function index of sub-compartment was 0.3333～0.7692,and the area of medium functional stand was 97.35%,with an area of 312409.72hm2.It is necessary to classify and manage stands with different levels of quality and ecological function.(3)County quality comprehensive score was 0.3199～0.6631,Cunninghamia lanceolata,Pinus elliottii,Larix kaempferi were superior in 30,12 and 6 counties,respectively,that is,the Cunninghamia lanceolata stands were better in 3 areas of 2 large(Wuling Mountain area in southwest Hubei and connected with Qinba Mountain area in northwest Hubei and Mufu Mountain area in southeast Hubei)and 1 small(Bebebie Mountain area in East Hubei),and the Pinus elliottii stands were better in 5 areas of 4 small(Xiangyang City in Qinba Mountain area,Xiaogan City in Dabie Mountain,Wuxue City and Daye City in Mufu Mountain area),However,Larix kaempferi stands were superior only in Wuling mountain area.While the main coniferous timber stands were distributed in 71 counties(city or district),among which 31 were superior counties.The comprehensive scores of provincial quality of Cunninghamia lanceolata,Pinus elliottii,Larix kaempferi and the main coniferous timber stand were 0.4580,0.4827,0.5908 and 0.4698,respectively,and the overall quality was not high;the result of the whole stand quality evaluation is consistent with that of the productivity level test of the plot.(4)The quality and ecological function of Larix kaempferi stands were relatively better.Among the forest categories,the functional index of the key public welfare forest was higher,and there were significant differences among different forest categories.According to the classification of stand origin(natural,artificial promotion,initiation,air seeding,direct seeding,seedling planting),natural stand had the best function,there were significant differences in the function index of other origin stands except for direct seeding and seedling planting.With the increase of age class,the stand quality of each species was the highest in the near mature forest,followed by the mature forest,and the lowest in the overmature forest,the stand quality of each age group was significantly different basically,however,the ecological function was improved with the increase of the age class,there was no significant difference between the overmature forest and the mature forest,and there was a very significant difference between the other age groups.Therefore,the tradeoff relationship between stand quality in the overmature forest stage and ecological function should be considered in the management process of main coniferous timber stand.