Subjects: Biology >> Botany >> Applied botany submitted time 2024-03-26 Cooperative journals: 《广西植物》
Abstract： To promote the restoration and reconstruction of ecosystem in the water-land ecotone, based on typical sample investigation, the variation patterns of vegetation species composition and diversity, and soil nutrients under different vegetation types were studied using Pearson correlation coefficient method and redundancy analysis method. The results were as follows: (1) There were significant differences in plant community structure and species diversity of different vegetation types (gravel zone, grass zone, shrub-grass zone, trees zone). As the submersed duration decreased, the water-land ecotone gradually evolved from scattered herbaceous plant communities to grass, shrub, and tree plant communities, and the α diversity of vegetation species (Shannon-Wiener index, Pielou index and Simpson index ) and vegetation coverage showed a gradually increasing trend, which were lowest value on the gravel zone and the highest on the trees zone. (2) There were significant differences in soil nutrient content among different vegetation types. With the decreased of submersed duration, soil organic matter content gradually increased, while soil water content, available nitrogen, available phosphorus, and available potassium showed a trend of first increasing and then decreasing, the maximum values of these nutrients mostly occurred in shrub-grass zone or trees zone, followed by grass zone, and gravel zone was the lowest. (3) Correlation and redundancy analysis showed that soil available nitrogen, available potassium, available phosphorus and organic matter were significantly positively correlated with various indicators of vegetation species α diversity, among which soil available nitrogen and available potassium had the strongest correlation with vegetation species diversity. In conclusion: different vegetation types in the Lijiang water-land ecotone have heterogeneous patterns of vegetation species composition and diversity as well as soil nutrients. Moderate submergence is beneficial for vegetation community aggregation and promoting soil nutrient accumulation. Herbaceous plants have stronger adaptability to moderate submergence environments. During the ecological restoration process of the Lijiang water-land ecotone, it is necessary to design restoration plans for different vegetation types and fully consider the relationship between vegetation species diversity and soil available nutrients.
Subjects: Biology >> Botany >> Applied botany submitted time 2023-07-26 Cooperative journals: 《广西植物》
Abstract： The ecological stoichiometry of fine root carbon (C), nitrogen (N), and phosphorus (P) is considered to reflect the strategies whereby plants adapt to the soil environment In order to gain an understanding of the seasonal changes in fine root C∶N∶P ratios in different forest types of a karst ecosystem, we measured the C, N, and P contents and ratios of living and dead fine roots in shrubbery and arbor forest vegetation, as well as the influence of abiotic and biotic factors. The results were as follows: (1) That C, N, and P contents in the fine roots of arbor forest vegetation were higher than those of shrubbbery vegetation, thereby indicating that the fine roots of arbor forest trees may by characterized by a stronger absorption and storage of nutrients than those of shrubbbery vegetation. In addition, we established that the contents of C in living fine roots were significantly higher than those in dead fine roots (P < 0.05), whereas in contrast, 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/dead fine roots of the two forest types were lower during the rainy season than during the dry season. Contrastingly, in shrubbery vegetation, whereas the N and P contents of living fine roots were higher during the rainy season than those in dry season, the opposite pattern was observed for the living fine roots of arbor forest vegetation. During the rainy season, the C∶N, C∶P, and N∶P ratios of living fine roots in shrubbery vegetation were lower than the values obtained during the dry season. Conversely, the C∶N and C∶P ratios of the living/dead fine roots of arbor forest vegetation 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 rainy season N∶P ratios tend to indicate that plants in shrubbery and arbor forest may be less P restricted during this season. (3) We also found that for both the living and dead fine roots of the two forest types, C contents were higher in plants 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 and forest trees growing on the lower 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 and the C∶P and N∶P ratios in trees growing on the upper slopes were higher than those of trees growing at other elevations, indicating that plants under these two forest types are 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 elevation should be taken into consideration when vegetation restoration is promoted, which would contribute to accelerating the restoration of karst ecosystems.
Subjects: Biology >> Botany >> Applied botany submitted time 2023-07-13 Cooperative journals: 《广西植物》
Abstract： In order to explore the effect of enzyme activities of plant root exudates on rhizosphere soil enzyme activities and nutrients in a karst ecosystem, the activities of β-1,4-glucosidase (βG), β-N-acetylglucosaminidase (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 were also analyzed. The results showed that 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. 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 had become significantly stronger. In addition, the activities of βG, NAG and LAP in rhizosphere soils and root exudates were positively correlated with organic carbon (SOC) and total nitrogen (TN) in rhizosphere soil, while the activity of ACP in rhizosphere soils and root exudates were positively correlated with available phosphorus (AP) in rhizosphere soil. The above results indicated that vegetation restoration had a positive effect on increasing activities of root exudates and soils. The enzymes of root exudates were the indispensable supplement for soils, and it played an important role in promoting carbon, nitrogen and phosphorus nutrient cycling. It will be that the regulation of root exudates and its enzyme activities may provide a new perspective for vegetation restoration in karst ecosystem.
Subjects: Biology >> Botany >> Applied botany submitted time 2022-03-30 Cooperative journals: 《广西植物》
Abstract： To explore the effects of land use and ecological restoration on soil enzyme activities and C:N:P ratios in the karst ecosystem, three land use types [disturbed land, pasture grassland, and orchard forest (Loquat)] and four restoration types (evergreen forest, deciduous forest, evergreen-deciduous mixed forest, and natural restoration forest), which are long-term positioning observation experimental plots of the Huanjiang Observation and Research Station for Karst Ecosystems, were selected. We measured the activities of four soil enzymes [β-1,4-glucosidase (βG), β-1,4-N-acetylglucosidase (NAG), leucine aminopeptidase (LAP), and alkaline phosphatase (ALP)], and analyzed the relationship between activities level and the C:N:P ratios and soil-associated physical and chemical factors. The results were as follows: (1) Enzyme activities were higher in the three land use types than in the restoration types. In addition, the activities of the four enzymes, enzymatic N:P, and enzymatic C:P of pasture grassland were higher than those in the other restoration types. The βG and ALP activities in the evergreen-deciduous mixed and deciduous forests were significantly higher than those in the natural restoration and evergreen forest, and NAG activity in the evergreen forest was significantly higher than that in the other three restoration types. The enzymatic N:P ratios of the evergreen-deciduous mixed forests were significantly lower than those in the other restoration types, as was the enzymatic C:P ratio of the deciduous forest. In addition, vector analysis of the enzyme activity measurement ratio showed that all land use and restoration types were limited by P. (2) The activities of the four enzymes were positively correlated with organic C, ammonia N (NH4+-N), and nitrate N (NO3--N), whereas negatively correlated with total P (TP). βG activity was positively correlated with available P (AP) and ALP activity was positively correlated with total N (TN). (3) Redundancy analysis showed that the levels of TP, NH4+-N, NO3--N, and AP explained 38.3%, 9.5%, 9.3%, and 8.0%, respectively, of the changes in soil enzyme activity and C:N:P ratios. Based on these results, the different land use and restoration types in karst areas were shown to generally exist under the limitation of soil P, which implies that the fixation and transformation of P should be the focus of soil quality improvement in the land use development and restoration process. Furthermore, soil enzyme activities, C:P ratios, and AP contents in pasture grassland, evergreen-deciduous mixed forest, and deciduous forest were higher than those in the other land use and restoration types. The result indicates that forage and deciduous plants are important for soil nutrient cycling and should be considered in the process of karst land use and restoration.
Subjects: Biology >> Botany >> Applied botany submitted time 2020-08-03 Cooperative journals: 《广西植物》
Abstract：为了了解不同林龄和密度马尾松人工林针叶和根系的养分变化特征，在广西南宁市横县镇龙林场选择了四种林龄（幼龄林、中龄林、成熟林和过熟林）和四种密度（低密度林、中低密度林、中高密度林和高密度林）马尾松林共8 种林分，分析了马尾松针叶和根系的C、N、P 含量和比值及其与土壤养分的关系。结果显示：（1）所有龄林与密度林的马尾松针叶N:P 比值均大于16，表明该地区马尾松明显受P 限制，幼龄林更加明显。（2）马尾松针叶C 含量随着林龄增长逐渐增大后下降，N 与P 含量呈微弱下降趋势，导致C:N 比值、C:P 比值和N:P 比值呈微弱上升趋势但没达到显著水平；根系C 含量、P 含量和C:N 比值逐渐增大，N 含量、C:P 比值和N:P 比值呈U 字型且都在幼龄林最大；针叶和根系在成熟林阶段均具有较高的P 含量和最高的C 含量。（3）中密度林的马尾松针叶的C 和N 含量较高且P 含量最高，C:N 比值较低且C:P 比值和N:P 比值最低；根系的C、N 和P 含量较高，而C:N 比值、C:P 比值和N:P 比值较低。（4）马尾松的根系养分尤其是P 含量在不同龄林和不同密度林之间的变化比针叶更加剧烈，且其与土壤养分之间的相关性比针叶更强。上述结果表明，马尾松人工林受P 限制，在低龄林加强P 肥管理和选择合适的林分密度（中等密度）则有利于缓解马尾松受P 限制的状态。
Subjects: Biology >> Botany >> Applied botany submitted time 2019-08-27 Cooperative journals: 《广西植物》
Abstract：为了了解不同林龄和密度对马尾松人工林凋落叶养分结构和归还状况的影响，选择广西南宁市横县镇龙林场的四种林龄（幼龄林、中龄林、成熟林和过熟林）和四种密度（低密度林、中低密度林、中高密度林和高密度林）马尾松林共8种林分作为研究对象，分析了未破碎和破碎两个不同降解阶段的凋落叶C、N、P含量及其生态化学计量学特征。结果表明：（1）不同林龄中，凋落叶初始C含量在过熟林和成熟林较高，N含量在过熟林和中龄林较高，而P含量没有显著变化，导致凋落叶的C﹕N比值和C﹕P比值在成熟林最大，而N﹕P比值不同林龄间无显著差异，说明处在较快生长期的幼龄林和中龄林马尾松可能对N和P养分的需求较大。（2）不同密度林中，随着林木密度的增加，凋落叶初始C含量逐渐升高，N含量无显著变化，而P含量在降低；高密度林凋落叶的初始C﹕P比值和N﹕P比值较高，说明高种植密度下马尾松可能对N和P养分的需求较大，P素重吸收较强。（3）不同林龄和不同密度马尾松林的破碎凋落叶C含量、C﹕N比值、C﹕P比值和N﹕P比值比未破碎凋落叶的低，而N和P含量较高，说明凋落物在降解过程中出现N和P养分的富集现象。（4）中林龄和较高种植密度的马尾松破碎凋落叶与未破碎凋落物的C含量差值最大，而C﹕N比值和C﹕P比值也较低，说明这两种林分的凋落叶C的降解速率可能较大。上述结果表明，中龄林和中高、高密度林的马尾松可能对N和P养分的需求较大，重吸收效率较高，且凋落叶C的潜在分解速率较高，可能利于有机碳较快进入土壤中。
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