Evaluation And Conservation Strategy Of Genetic Resources Of Pinus Bungeana Zucc.

Pinus bungeana is an endemic species to China, with high economic and ecologicalvalues for landscaping and afforestation. Owing to long-term over-exploitation, natural forestresources of Pinus bungeana has been severely damaged at present and natural populationsmainly found in the top of hills in poor habitats usually isolated and fragmented. Geneticdiversity in populations is facing tough challenges. On the basis of survey of the naturaldistribution and habitat, natural regeneration and population structure were evaluated; then,genetic variation of different groups were analyzed using molecular markers and provenancetest. Finally, conservation strategies were formulated according to the distribution pattern ofgenetic diversity, regeneration status and the ecological risks. The main conclusions are asfollows:1, Through literature review and field survey, natural distribution of Pinus bungeana weremanly in the Mountains of warm temperate and northern subtropical zone; the range of naturallatitudinal was between30°52'~38°25' and longitudinal was between103°36'~115°17'. Thedistribution was mainly in the Taihang Mountain, Lvliang Mountain, Qinling Mountain andDaba Mountain and distribution in Daba Mountain was scattered. Southern boundary of Pinusbungeana was found in Badong county, Hubei Province. Southeast boundary of the distributionwas found from Badong county, Yuan'an county, Nanzhang county to Danjiangkou city inHubei Province. Vertical distribution of Pinus bungeana was largely fluctuated due to theterrain. In counties of Luanchuan, Luoning, Lantian in eastern Qinling Mountain, Pinusbungeana were mainly distributed in elevations between758~1450meters. In counties ofQinyang, Lingchuan, Yuci in Taihang Mountain, Pinus bungeana were mainly distributed inelevations between800~1410meters. In counties of Xixiang, Nanzhang, Yuan'an and city ofDanjiangkou in Daba Mountain, Pinus bungeana were mainly distributed in elevationsbetween443~1246meters. In Pu county in Lvliang Mountain were mainly distributed inelevations between1200~1360meters. In Yicheng county in Zhongtiao Mountain were mainlydistributed in elevations between1300~1450meters. In counties of Kang, Cheng and Tianshuicity in Qinling Mountain, Pinus bungeana were mainly distributed in elevations between 1052~1517meters. Fragment was the main shape in distribution of Pinus bungeana andpopulations exist mainly in mountaintop and nearby place in forms of pure forest or dominantspecies in mix forest.2, Study of natural regeneration in different populations showed that: natural regenerationwere better in Taihang Mountain, Zhongtiao Mountain Lvliang Mountain and the west side ofQinling Mountain but poor in areas of Nanzhang county, Yuan'an county, Xixiang county andDanjiangkou city in Daba Mountain; shortage of seedlings exist in most of the populations andthe better regeneration place within population were mainly in forest gap and forest edge.Regeneration was closely associated with growth status of other vegetation.3, Population structure was analysed using method of diameter classes instead of ageclasses, the result showed that: Age classe structure was different in different locations and alsofluctuated in the same location. In Daba Mountain, individuals were older and distributedmainly in Ⅲ~Ⅳ age classes. In this region, populations were in a stage of mature and tend todecline. In Taihang Mountain, Lvliang Mountain and Zhongtiao Mountain, individuals wasyoung and mainly distributed between Ⅰ~Ⅲ age classes. Populations in this region werestable temporarily, but have some risks for lack of regeneration seedlings. In Qinling Mountain,the structure of populations changes larger, individuals mainly distributed betweenⅠ~VI ageclasses and lack of first class seedlings.4,309pars of SSR primes of other species in Pinus were screened using8individuals indifferent populations. The result showed that:86pars of primes can be successfully amplifiedout of309pairs of SSR primers, accounting for27.83%, and7were polymorphic primersaccounting for2.27%; universal primers of other Pinus were relatively low in Pinus bungeana.5, The Hardy-Weinberg equilibrium test indicated that most of the populations were in anunbalanced state at one or more loci and inbreeding existed in most of the populations. At locusY7, heterozygous were exist only in P10, P11, P12, and there were also heterozygous completeabsence in other loci. Most of the populations were subjected to effects of genetic drift,mutation, migration and the choice of evolutionary.6,14polymorphic loci were detected in663individuals among21natural populationsusing7pairs of EST-SSR primes. Mean of Ne,I,Ho,He,Nei's were1.3097,0.3127,0.2214,0.1994,0.1963respectively.11alleles and14genotypes were detected in192artificial populations. The average of Ne,I,Ho,He,Nei's were1.2263,0.2466,0.1935,0.1511,0.1487respectively. Compared with artificial populations, the natural populations have ahigher genetic diversity.7, Genetic diversity of different populations were compared using parameters of Ne,I,Ho,He,Nei's. The result showed that: The ranking of populations was roughly the same usingdifferent genetic diversity parameters. P16in southwestern part of Qinling Mountain and P22in southern part of Daba Mountain have the highest genetic diversity, other populations withhigh genetic diversity were also in the west of Qinling Mountain and Daba Mountain. Thepopulations with low genetic diversity were P17,P18,P19in the east of Qinling Mountain andpopulations in Taihang Mountain,Lvliang Mountain and Zhongtiao Mountain. Centers ofgenetic diversity were mainly in the west and the south of the distribution and the geneticdiversity in distribution tended to reduce from west to east and from south to north.8, Analysis of genetic differentiation showed that: The average of Fst and Nm were0.2152and0.9119respectively, gene flow was less and genetic differentiation was high amongpopulations. Populations can be divided into four groups at the genetic distance of0.05. Thefour groups were P14; P15; P10, P11, P13, P16, P22and the remaining populations.9, Provenance trials in Beijing and Lushi of Henan Province showed that: Adaptability ofPinus bungeana was affected mainly by the distance between the growing site and the origin ofseed source and decreased in a regular pattern with increase of the distance. Growth trait ofPinus bungeana was affected mainly by the geographical distribution and changed in trend ofnorth east to south west from large to small. Growth rates from high to low were Tianshuicounty(103.42cm,96.75cm), Liangdang county(99.57cm,87.75cm), Lantian county96.61cm,85.85cm), Beijing(93.17cm,81.89cm)and Xiaoyi county(88.24cm,75.88cm).10, Conservation strategy was drafted according to the genetic variation pattern andregeneration of Pinus bungeana. In west-middle section of Qinling Mountain, the populationsof Pinus bungeana have high diversity and evident genetic differentiation, should be protectedwith priority and increase the number of populations appropriately for conservation.Populations in this region have the ability of natural regeneration, so in situ should be the mainconservation form. The Daba Mountain populations have the high level of genetic diversity;but the population sizes were small and the condition of natural regeneration was poor; so the populations in this region has the risk of extinction and ex situ should be the main conservationform. The populations in Taihang Mountain, LvLiang Mountain, and ZhongTiao Mountainhave simple genetic structure and low level of genetic differentiation, but regeneration wasrelatively good; so, in situ should be the main conservation form. Populations in the east of theQinling Mountain have simple genetic structure and regeneration was poor, facing high risk ofextinction, so ex situ should be the main conservation form.