Quick Identification of Genetic Provenances and Best Practice Woodland Management of Chinese Pine (Pinus tabuliformis)

Chinese pine (Pinus tabuliformis) is one of the most widespread, ecologically and economically important tree species in North China. In this study, we analyzed and compared the genetic diversity and population structure of 158 individuals from 17 populations of P. tabuliformis, by group III, a new mitochondrial marker system (nad1-2, nad4-3, nad5-1 and nad7-1) with two other groups of marker systems. In contrast to the conservation in the evolution of the mitochondrial sequence, the new mitochondrial marker system of P. tabuliformis shows as extremely high polymorphism as 25, whose haplotypes are more than four times of the group I marker system (nad1-2, nad4-3, and nad5-1) as 8 haplotypes. Although the group II, nad7-1 (19 haplotypes), showed high resolution in the provenance identification of P. tabuliformis, the new mitochondrial marker system is more accurate for detection of specific groups like HL, WT and NS and powerful to differentiate populations between GD and SS. The results suggested that the new mitochondrial marker system is as high as the resolution of GBS (genotype by seqencing). It is much more available and will be of great help to provenance identification and molecular assisted breeding of P. tabuliformis. This study will make theoretical foundation for the following studies on the evaluation, cultivation and germplasm management of P. tabuliformis populations and aid the breeding, biodiversity and conservation programs of forest species.

Response of density-related fine root production to soil and leaf traits in coniferous and broad-leaved plantations in the semiarid loess hilly region of China

Fine roots are the most active and functional component of root systems and play a significant role in the acquisition of soil resources. Density is an important structural factor in forest plantations but information on changes in fine roots along a density gradient is limited. In this study, plantations of black locust (Robinia pseudoacacia L.) and Chinese pine (Pinus tabuliformis Carr.) with four density classes were analyzed for the influence of soil and leaf traits on fine root growth. Fine root biomass increased with stand density. High fine root biomass was achieved through increases in the fine root production and turnover rate in the high-density black locust plantations and through an increase in fine root production in the pine plantations. In the high-density Chinese pine stand, there was a high fine root turnover which, coupled with high fine root production, contributed to a high fine root biomass. Overall, fine root production and turnover rate were closely related to soil volumetric water content in both kinds of plantations, while fine root biomass, especially the component of necromass, was related to soil nutrient status, which refers to phosphorous content in black locust plantations and nitrogen content in Chinese pine plantations. There was a close linkage between leaf area index and fine root dynamics in the black locust plantations but not in the pine plantations.

Water Use by Chinese Pine Is Less Conservative but More Closely Regulated Than in Mongolian Scots Pine in a Plantation Forest, on Sandy Soil, in a Semi-Arid Climate

The diversity of plant water use patterns among species and ecosystems is a matter of widespread debate. In this study, Chinese pine (Pinus tabuliformis, CP) and Mongolian Scots pine (Pinus sylvestris var. mongolica, MP), which is co-exist in the shelterbelt plantations in the Horqin Sandyland in northern China, were chosen for comparison of water use traits by monitoring xylem sap flow alongside recordings of the associated environmental factors over four growing seasons. Continuous sap flux density measurements were converted into crown projected area transpiration intensity (Tr) and canopy stomatal conductance (Gs). The results indicated that MP showed a higher canopy transpiration intensity than in CP, with Tr daily means (±standard deviation) of 0.84 ± 0.36 and 0.79 ± 0.43 mm⋅d–1, respectively (p = 0.07). However, the inter-annual variability of daily Tr in MP was not significant, varying only approximately a 1.1-fold (p = 0.29), while inter-annual variation was significant for CP, with 1.24-fold variation (p < 0.01). In particular, the daily mean Tr value for CP was approximately 1.7-times higher than that of MP under favorable soil moisture conditions, with values for relative extractable soil water within the 0–1.0 m soil layer (REW) being above 0.4. However, as the soil dried out, the value of Tr for CP decreased more sharply, falling to only approximately 0.5-times the value for MP when REW fell to < 0.2. The stronger sensitivity of Tr and/or Gs to REW, together with the more sensitive response of Gs to VPD in CP, confirms that CP exhibits less conservation of soil water utilization but features a stronger ability to regulate water use. Compared with MP, CP can better adapt to the dry conditions associated with climate change.

Urban-rural gradients in soil nutrients beneath Chinese pine (Pinus tabulaeformis Carr.) are affected by land-use

Urban-rural gradients of soil nutrients may be affected by many factors including land use, vegetation cover, and management. In this study, we investigated soil nutrients along urban-rural gradients beneath Chinese pine (Pinus tabulaeformis Carr.) in parks, neighborhoods and roadsides in Beijing, China. Soil levels of organic carbon, calcium, and magnesium are significantly higher in neighborhoods and parks than in roadsides. Soil nitrate-nitrogen levels are higher in neighborhoods than in roadsides. Soil magnesium levels are higher in neighborhoods than in parks. Interestingly, soil moisture, nitrate-nitrogen, calcium, magnesium, and available phosphorus and potassium all decreased in parks along the urban to rural gradient. Soil available phosphorus also declined along urban-rural gradients in neighborhoods. Thus, land use plays an important role in modifying urban-rural gradients of soil nutrients.

Molecular and morphological characterisation of Laimaphelenchus spiflatus n. sp. (Nematoda: Aphelenchoididae) from China

Summary Laimaphelenchus spiflatus n. sp. isolated from declining Chinese pine, Pinus tabuliformis, is described and illustrated. The new species can be characterised by its relatively long body size of 1150 ± 108 (976-1437) μm for females and 1092 ± 78.6 (905-1235) μm for males, lateral field with four lines, females with a long vulval flap, and tail conoid, slightly ventrally curved and ending in a stalk having 8-12 projections when observed with SEM. Males are common, with 27.3 (23.4-28.8) μm long spicules having blunt (not well-developed) condylus and rostrum and truncate simple distal tip, and four caudal papillae. By having a vulval flap, four lateral lines and tail end with a stalk (without four tubercles), the new species comes close to L. preissii, L. simlaensis, and L. unituberculus, but can be differentiated from them by morphological characters and morphometric data. In phylogenetic analyses using near full length 18S and D2-D3 expansion segments of 28S rDNA, Laimaphelenchus spiflatus n. sp. appeared as an independent lineage separated from the other Laimaphelenchus spp. that are currently sequenced for their aforementioned genomic regions.