2024/4/1 11:07:45 *, LI Dongxing, LI Jianxing, LU Fang]]> CHEN Ting, TAN Yanfang, LU Shuhua^*, LI Dongxing, LI Jianxing, LU Fang 7true 2. Based on data from three surveys conducted in 2007, 2012, and 2017, the dynamics of community spatial structure were analyzed using the spatial structure parameters, i. e., angular scale(W_i), mixing degree(M_i), and size ratio(U_i). The results were as follows:(1)The univariate distribution results of spatial structure parameters revealed that the forest structure gradually shifted towards a slightly clumped distribution state as the stand age increased between 2007 and 2017. The mixing degree was at a level of strong mixing and showed a tendency towards extreme mixing. In terms of the size ratio, the stand exhibited a moderate state, shifting towards subdominance as the stand grew.(2)The study of spatial structure for different diameter classes of trees showed that the anglular scale, size ratio, and mixing degree of trees in diameter classes 1-15 cm gradually increased with stand growth. As the diameter class increased, the values of the size ratio showed a decreasing trend while the mixing degree showed an increasing trend.(3)The study of spatial structure for dominant tree species revealed that, during the period from 2007 to 2017, all five dominant tree species groups exhibited a slightly clumped distribution. The size ratio showed a tendency towards subdominance and a moderate distribution state, while the mixing level was at a high degree and gradually shifted towards extreme mixing. In conclusion, the karst evergreen and deciduous broad-leaved forest in Mulun currently exhibits a slightly clumped distribution, a strong degree of mixing, and a tendency towards subdominance. The community is relatively stable, the stand regeneration is in good condition, and the forest is gradually transitioning towards a climax community. The analysis of the dynamic changes in vegetation structure in karst evergreen and deciduous broad-leaved forests is of great significance for predicting the future development and changes of forests.]]> 2024/4/1 11:07:45 1,2,3, DU Hu^2,3, SONG Tongqing^2,3, ZENG Fuping^2,3, PENG Wanxia^2,3, ZHANG Lijin^2,3,4, GAN Jiang^2,3,4, YANG Gairen^1*]]> YANG Zhiqi^1,2,3, DU Hu^2,3, SONG Tongqing^2,3, ZENG Fuping^2,3, PENG Wanxia^2,3, ZHANG Lijin^2,3,4, GAN Jiang^2,3,4, YANG Gairen^1* 6true 2024/4/1 11:07:45 1,2, YUAN Kewei^1,2, LIANG Zhihui^1,2, LI Yuling^1,2, LIANG Shichu^1,2*]]> LIN Haili^1,2, YUAN Kewei^1,2, LIANG Zhihui^1,2, LI Yuling^1,2, LIANG Shichu^1,2* 5true Mahonia fortunei(H-SD), walnut with corn(H-YM), and monoculture walnuts(H-D). The physicochemical properties and microbial characteristics of the walnut rhizosphere and non-rhizosphere soils under different planting modes were analyzed using laboratory chemical experiments and Illumina Hiseq PE300 high-throughput sequencing technology. The results were as follows:(1)The walnut rhizosphere soils of different modes exhibited different degrees of enrichment in total nitrogen(TN), total phosphorus(TP), total potassium(TK), available phosphorus(AP), soil organic carbon(SOC), and exchangeable calcium, while available nitrogen(AN)showed a deficiency. Among them, H-SS showed significant enrichment effects on TN, TP, and SOC, while H-YM demonstrated the best enrichment effects on AP, AK, and exchangeable calcium.(2)Sucrase activity, microbial biomass carbon and nitrogen, and bacteria all exhibited significant rhizosphere effects, with H-YM showing the highest sucrase activity, phosphatase activity, and microbial biomass carbon. However, intercropping modes reduced the rhizosphere effects of microbial biomass nitrogen and bacteria.(3)Under the three intercropping modes, the Shannon index of rhizosphere soil bacteria was higher than that of monoculture walnuts.(4)Intercropping could enhance the diversity of rhizosphere soil bacteria. Moreover, the diversity of rhizosphere soil microorganisms was mainly influenced by nutrients, while non-rhizosphere soil was primarily affected by enzyme activities. In conclusion, intercropping can increase the enrichment ratio of rhizosphere nutrients, enhance soil enzyme activities, and promote microbial proliferation. Among the four different planting modes, H-SS shows significant enrichment effects on TN, TP, and SOC in rhizosphere soil, and it also has the highest soil bacterial content. H-YM exhibits better enrichment effects on AP, AK, and exchangeable calcium in rhizosphere soil. Therefore, in practical production, intercropping with mulberry or corn can be chosen based on local farming practices to optimize land use and improve ecological benefits. This study is of great significance for the development of sustainable agriculture in the northwest Guangxi karst area and provides a scientific basis for agricultural production and ecological conservation in similar ecological environments. Additionally, this research offers new ideas and methods for promoting agricultural modernization and facilitating the rational utilization of land resources and improvements in the ecological environment in karst area.]]> 2024/4/1 11:07:45 1,2, YU Yuefeng², ZENG Chengcheng², LI Qin², SU Lirong², QIN Fang², YANG Gairen^1*, HE Tieguang²]]> WEI Jianhua^1,2, YU Yuefeng², ZENG Chengcheng², LI Qin², SU Lirong², QIN Fang², YANG Gairen^1*, HE Tieguang² 4true P<0.05), but N and P contents in living fine roots were lower than those in dead fine roots.(2)It was found that the contents of C in the living and dead fine roots of the two forest types were lower during the rainy season than during the dry season. The N and P contents of living fine roots of shrubs were higher during the rainy season than those in dry season, the opposite pattern was observed for the living fine roots of arbors. During the rainy season, the C:N, C:P, and N:P ratios of living fine roots in shrubland were lower than the values obtained during the dry season. Conversely, the C:N and C:P ratios of the living and dead fine roots of arbors were higher during the rainy season than in the dry season, whereas the values for the N:P ratio were lower during the rainy season than during the dry season. The lower N:P ratios of rainy season tended to indicate that plants in shrubland and arbor forest may be less P restricted during this season.(3)It was found that for both the living and dead fine roots of the two forest types, C contents were higher in trees growing on the upper slopes than in those growing on the middle and lower slopes, whereas the contents of N and P were higher in shrubs growing on the lower slopes and in arbors growing on the middle slopes. Furthermore, the C:N, C:P, and N:P ratios of living and dead fine roots were found to be relatively higher in shrubs growing on the upper slopes. In the case of arbor forest, the C:N ratios of living and dead fine roots in trees growing on the lower slopes were higher than other slopes, however the C:P and N:P ratios in trees growing on the upper slopes were higher than those of trees growing at other slopes, indicating that trees under these two forest types were strongly influenced by P limitation in the upper slopes, but only weakly affected on the middle and lower slopes.(4)Redundancy analysis revealed that forest type, available phosphorus, and season were the main factors influencing the contents and ratios of C, N, and P nutrients in fine roots, and could explain 18.8%, 6.6%, and 6.5% of the observed variation, respectively. These findings indicate that the effects of changes in the N:P ratio associated with differences in forest type, season, and slope should be taken into consideration when vegetation restoration is promoted, which will contribute to accelerating the restoration of karst ecosystems.]]> 2024/4/1 11:07:45 1, ZHANG Wei², QIN Menger¹, LIANG Yueming³, PAN Fujing^1*]]> DOU Li¹, ZHANG Wei², QIN Menger¹, LIANG Yueming³, PAN Fujing^1* 3true β-1,4-glucosidase( βG), β-N-acetyl-glucosaminidase(NAG), leucine aminopeptidase(LAP), and acidic phosphatase(ACP)of fine root exudates and rhizosphere soils in four vegetation restoration stages, which are shrub-grassland, shrubland, shrub-arbor forest and arbor forest, were measured. And, their relationships with soil carbon(C), nitrogen(N), phosphorus(P)contents were analyzed. The results were as follows:(1)The four enzyme activities of rhizosphere soils and root exudates were significantly higher in the late stage of vegetation restoration than in the early stage of vegetation restoration. The enzyme activities C:P to N:P ratios of root exudates in arbor forest were significantly higher than those of other three stages, while the two parameters of rhizosphere soils were opposite.(2)Correlation analysis showed that the enzyme activities of root exudates were positively correlated with the corresponding soil enzyme activity. Compared with the enzyme activities of root exudates, the correlation between soil enzyme activity and related nutrients became significantly stronger. In addition, the enzyme activities of βG, NAG and LAP in rhizosphere soils and root exudates were positively correlated with soil organic carbon(SOC)and total nitrogen(TN)in rhizosphere soil, while the enzyme activities of ACP in rhizosphere soils and root exudates were positively correlated with available phosphorus(AP)in rhizosphere soil. The above results indicate that vegetation restoration has a positive effect on increasing enzyme activities of root exudates and soils. The enzymes of root exudates are the indispensable supplement for soils, and play an important role in promoting carbon, nitrogen and phosphorus nutrient cycling. To sum up, it will be that the regulation of root exudates and its enzyme activities may provide a new perspective for vegetation restoration in karst ecosystem.]]> 2024/4/1 11:07:45 1, LI Zhen⁴, DOU Li¹, LIANG Yueming³, ZHANG Wei²,WANG Jing⁵, PAN Fujing^1*]]> QIN Menger¹, LI Zhen⁴, DOU Li¹, LIANG Yueming³, ZHANG Wei²,WANG Jing⁵, PAN Fujing^1* 2true Pinus elliottii and Liriodendron chinense in the rocky desertification area of Western Hunan, taking Pinus elliottii and Liriodendron chinense artificial coniferous and broad-leaved mixed forest in the rocky desertification area of Western Hunan as the research object, this paper provides a theoretical basis for vegetation restoration, plantation structure optimization, and soil improvement in this area. The stand structure and soil physicochemical properties of existing stands were analyzed using plant community analysis and field sampling detection methods. Winklemass 1.0 was used to calculate the spatial structure parameters of the stands, and three-dimensional discrete random variables were used to analyze the spatial distribution pattern of dominant species. The results were as follows:(1)A total of trees of 897 plants·hm^-2 with diameter at breast height(DBH)≥ 2 cm in the stand, belonging to 15 families and 16 genera. The main forest layer was Pinus elliottii, with an average DBH of 32.3 cm and an important value of 44.2%; the secondary forest layer was the broad-leaved tree, with the majority of young and middle-aged trees. Cinnamomum camphora and Liriodendron chinense were the dominant species, with important values of 17.1% and 13.2%, respectively. In addition, there were many natural regeneration species at the disadvantaged ecological niche.(2)The horizontal distribution pattern of trees tended to be random(W^-=0.503); the overall trend of forest stands tended to transition towards mediocrity and disadvantage(U^-=0.505); the degree of interspecific isolation was relatively high(M^-=0.689), and the mixed forest was in good condition. Three-dimensional discrete random variables of spatial structure parameters showed that 87.3% of Pinus elliottii was dominant and sub-dominant, 41.7% of Liriodendron chinense was sub-dominant, 26.9% was moderate, 23.5% of Cinnamomum camphora was moderate, 56.8% was inferior and absolute inferior.(3)The pH value of forest soil tended to be neutral; compared with abandoned land, the bulk density, water capacity, porosity, organic carbon, total potassium, total nitrogen, and total phosphorus of the forest soil had significantly improved. However, the forest soil was still relatively barren, with local soil compaction and poor water retention ability. To sum up, after 43 years of growth of Pinus elliottii and Liriodendron chinense as pioneer species, the stand has a trend of succession to the uneven-aged forest and intensive mixed forest. However, the number of young and middle-aged broad-leaved trees in the forest is relatively large, and faults appear in the near mature forest. The elderly coniferous trees occupy the dominant ecological location. Needles need to be drawn to supplement the broad-leaved trees, interspersed to cultivate the broad-leaved trees, and selective felling the inferior trees, to promote the structural succession of the forest with mainly sunny broad-leaved trees, followed by mesophytic and shade-tolerant broad-leaved trees. The results of this study provide a theoretical basis for vegetation restoration, plantation structure optimization and soil improvement in the rocky desertification area of Western Hunan.]]> 2024/4/1 11:07:45 1, ZHU Ninghua^1*, ZHOU Guangyi², YUAN Xingming³, JIANG Dai¹, DONG Yanyan¹, YAN Runzhi³]]> WANG Yixuan¹, ZHU Ninghua^1*, ZHOU Guangyi², YUAN Xingming³, JIANG Dai¹, DONG Yanyan¹, YAN Runzhi³ 1true