Browsing by Subject "POPULUS-CATHAYANA"

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  • Dong, Tingfa; Duan, Baoli; Korpelainen, Helena; Niinemets, Ulo; Li, Chunyang (2019)
    Following asymmetric pruning of leaves and/or roots, the functional balance of distribution of carbon, but not of nitrogen, in Cunninghamia lanceolata is more readily achieved for the roots and leaves on the same side of the pruning compared with those on the opposite side. Abstract The functional balance between leaves and roots is believed to be mediated by the specific location of shoots and roots, i.e. differences in transport distances and degrees of organ connectivity. However, it remains unknown whether the adaptive responses of trees to biomass removal depend on the relative orientation of leaf and root pruning. Here, we applied five pruning treatments to saplings of Cunninghamia lanceolata (Chinese fir) under field and glasshouse conditions, namely no pruning (control), half of lateral branches pruned, half of lateral roots pruned, half of the branches and roots pruned on the same side of the plant, and half of the branches and roots pruned on opposite sides of the plant. The effects of pruning on the growth, carbon storage and allocation, and physiology of leaves and fine roots on the same and opposite sides of the plant were investigated. Compared with the effect of root-pruning on leaves, fine roots were more limited by carbon availability and their physiological activity was more strongly reduced by shoot pruning, especially when branches on the same side of the plant were removed. Pruning of branches and roots on the opposite side of the plant resulted in the lowest carbon assimilation rates and growth among all treatments. The results of a stable-isotope labeling indicated that less C was distributed to fine roots from the leaves on the opposite side of the plant compared to those on the same side, but N allocation from roots to leaves depended less on the relative root and leaf orientation. The results collectively indicate that the functional responses of C. lanceolata to pruning are not only determined by the source-sink balance model but are also related to interactions between leaves and fine roots. We argue that the connectivity among lateral branches and roots depends on their relative orientation, which is therefore critical for the functional balance between leaves and fine roots.
  • Guo, Qingxue; Song, Haifeng; Kang, Jieyu; Korpelainen, Helena; Li, Chunyang (2018)
    Knowledge of how competition and facilitation affect photosynthetic traits and nitrogen metabolism contributes to understanding of plant-plant interaction mechanisms. We transplanted two larch species, Larix kaempferi and L. olgensis, to establish intra- and interspecific interaction experiments under different types of soil. Experiment 1: Two different soil types were selected, one from a c. twenty years old L. kaempferi plantation (named larch soil) and another from a secondary natural forest (named mixed forest soil). The experiment included three types of plant interactions (L kaempferi + L. kaempferi, L. olgensis + L. olgensis, and L. kaempferi + L. olgensis) and two soil types. Experiment 2: N fertilization was applied to larch soil. The experiment included the same three types of plant interactions as in Experiment 1 and two N treatments. The growth of L kaempferi was negatively affected by larch soil and accelerated by N fertilization, particularly under interspecific interaction. The effects of soil type combined with plant-plant interactions or N fertilization influenced the chlorophyll pigment content, net photosynthetic rate (Pn), photosynthetic N use efficiency (PNUE) and total non-structural carbohydrates of leaves (TNC). CM a/Chl b (ratio of chlorophyll a to chlorophyll b) was higher when the growth of L. kaempferi was facilitated by the presence of L olgensis in mixed forest soil. However, the ratio significantly declined when L. kaempferi confronted strong competition from L. olgensis in larch soil without N fertilization. Under N fertilization in larch soil, Chl a/Chl b of L. olgensis significantly increased by the presence of L. kaempferi. Plant-plant interactions and soil types affected the number of chloroplasts, especially in L. kaempferi, which had a greater number of chloroplasts under interspecific interactions than in monoculture when growing in mixed forest soil. L. olgensis enhanced its ability to absorb N-NO3- under interspecific interactions in larch N- soil, while L. kaempferi enhanced its ability to absorb N-NH4+ under interspecific competition in mixed forest soil. Competition or facilitation modified the photosynthetic traits and nitrogen metabolism depending on the type of soil. Differences in these physiological processes contribute to divergent performance among individuals growing under interspecific or intraspecific competition, or in isolation.
  • Li, Yan; Kang, Jieyu; Li, Zhijun; Korpelainen, Helena; Li, Chunyang (2020)
    Aims Populus deltoides and P. euramericana are widely used in China as major forestry species. At present, little is known about their responses to nitrogen (N) deficiency when grown in monocultures or mixed plantations. The aim of this investigation was to analyze the growth, and morphological and physiological responses of P. deltoides and P. euramericana to different N levels under competition conditions. Methods We employed two Populus species (P. deltoides and P. euramericana) to discover how N deficiency affects plant traits under different competition types (P. deltoides x P. deltoides, intraspecific competition; P. euramericana x P. euramericana, intraspecific competition; P. deltoides x P. euramericana, interspecific competition). Potted seedlings were exposed to two N levels (normal N, N deficiency), and nitrogen- and competition-driven differences in growth, morphology and physiology were examined. Important Findings Under normal N conditions, interspecific competition significantly decreased the total root weight, root mass fraction (RMF), root-shoot ratio (R/S) and carbon/nitrogen ratio (C/N), and increased the leaf dry weight, leaf mass fraction and total leaf area of P. euramericana compared with intraspecific competition. The same conditions significantly affected the growth and morphological variables of P. deltoides, except for the dry weight of fine roots, R/S, specific leaf area, RMF, total nitrogen content and C/N compared with intraspecific competition. In addition, chlorophyll a (Chla), total chlorophyll (Tchl), carotenoid contents (Caro) and the carbon isotope composition (delta C-13) of P. deltoides were significantly lower in interspecific competition than in intraspecific competition, but no difference was detected in P. euramericana. The effects of N deficiency on P. deltoides under intraspecific competition were stronger than under interspecific competition. In contrast, the effects of N deficiency on P. euramericana between intraspecific and interspecific competition were not significantly different. These results suggest that under normal N condition, P. deltoides is expected to gain an advantage in monocultures rather than in mixtures with P. euramericana. Under N deficiency, the growth performance of P. euramericana was more stable than that of P. deltoides under both cultivation modes.
  • Yu, Lei; Song, Mengya; Lei, Yanbao; Duan, Baoli; Berninger, Frank; Korpelainen, Helena; Niinemets, Ülo; Li, Chunyang (2017)
    Intra- and interspecific competition and modifications in environmental characteristics are the main drivers of plant community dynamics, but few studies have investigated the combined effects of competition and phosphorus (P) availability on ecological succession. Seedlings of conifers Abies fabri and Picea brachytyla were collected from the late-stage Hailuogou glacier retreat area and grown under different P regimes (control and P fertilization) to investigate the impact of intra- and interspecific competition on photosynthetic capacity, resource (water, N and P) use efficiency and growth performance in two types of native soil. In the control treatment, there were no differences in the total biomass of A. fabri between the two competition patterns under either type of soil, whereas interspecific competition decreased the total biomass of P. brachytyla grown in the soil collected from A. fabri plots. However, under P fertilization, A. fabri individuals exposed to interspecific competition showed a stronger competitive ability, as their total biomass, absolute height growth rate, net photosynthetic rate, water use efficiency (delta C-13) and leaf P content were significantly higher under interspecific competition compared to intraspecific competition. No differences in these traits were detected in P. brachytyla between the two competition patterns. The results indicated that P plays an important role in determining asymmetric competition patterns among Pinaceae species. The interactive effect of interspecific competition and P availability highlighted here could influence the community composition and dynamics of plants during late stage primary succession in a glacier retreat area.
  • Yu, Lei; Dong, Haojie; Huang, Zongdi; Korpelainen, Helena; Li, Chunyang (2021)
    The continuously increasing atmospheric carbon dioxide concentration ([CO2]) has substantial effects on plant growth, and on the composition and structure of forests. However, how plants respond to elevated [CO2] (e[CO2]) under intra- and interspecific competition has been largely overlooked. In this study, we employed Abies faxoniana Rehder & Wilson and Picea purpurea Mast. seedlings to explore the effects of e[CO2] (700 p.p.m.) and plant-plant competition on plant growth, physiological and morphological traits, and leaf ultrastructure. We found that e[CO2] stimulated plant growth, photosynthesis and nonstructural carbohydrates (NSC), affected morphological traits and leaf ultrastructure, and enhanced water- and nitrogen (N)- use efficiencies in A. faxoniana and P. purpurea. Under interspecific competition and e[CO2], P. purpurea showed a higher biomass accumulation, photosynthetic capacity and rate of ectomycorrhizal infection, and higher water- and N-use efficiencies compared with A. faxoniana. However, under intraspecific competition and e[CO2], the two conifers showed no differences in biomass accumulation, photosynthetic capacity, and water- and N-use efficiencies. In addition, under interspecific competition and e[CO2], A. faxoniana exhibited higher NSC levels in leaves as well as more frequent and greater starch granules, which may indicate carbohydrate limitation. Consequently, we concluded that under interspecific competition, P. purpurea possesses a positive growth and adjustment strategy (e.g. a higher photosynthetic capacity and rate of ectomycorrhizal infection, and higher water- and N-use efficiencies), while A. faxoniana likely suffers from carbohydrate limitation to cope with rising [CO2]. Our study highlights that plant-plant competition should be taken into consideration when assessing the impact of rising [CO2] on the plant growth and physiological performance.
  • Yu, Lei; Song, Mengya; Xia, Zhichao; Korpelainen, Helena; Niinemets, Ulo; Li, Chunyang (2019)
    There is a limited understanding of the impacts of global warming on intra- and interspecific plant competition. Resolving this knowledge gap is important for predicting the potential influence of global warming on forests, particularly on high-altitude trees, which are more sensitive to warming. In the present study, effects of intra- and interspecific competition on plant growth and associated physiological, structural and chemical traits were investigated in Abies faxoniana and Picea purpurea seedlings under control (ambient temperature) and elevated temperature (ET, 2 degrees C above ambient temperature) conditions for 2 years. We found that A. faxoniana and P. purpurea grown under intra- and interspecific competition showed significant differences in dry matter accumulation (DMA), photosynthetic capacity, nutrient absorption, nonstructural carbohydrate (NSC) contents and leaf ultrastructure under ET conditions. ET increased leaf, stem and root DMA of both conifers under both competition patterns. Moreover, under ET and interspecific competition, P. purpurea had overall superior competitive capacity characterized by higher organ (leaf, stem and root) and total DMA, height growth rate, net photosynthetic rate, specific leaf area, water use efficiency (delta C-13), leaf and root N and NSC concentrations and greater plasticity for absorption of different soil N forms. Thus, the growth of P. purpurea benefitted from the presence of A. faxoniana under ET. Our results demonstrated that ET significantly affects the asymmetric competition patterns in subalpine conifer species. Potential alteration of plant competitive interactions by global warming can influence the composition, structure and functioning of subalpine coniferous forests.
  • Li, Junyu; Wu, Guoxi; Guo, Qingxue; Korpelainen, Helena; Li, Chunyang (2018)
    There are significant differences in the morphological and physiological responses of larch species with contrasting growth rates under fertilization. However, little is known about species-specific differences in responses to nutrient imbalance caused by fertilization. Therefore, in this study, the effects of nitrogen (N) and phosphorus (P) fertilization on the morphological, physiological and chloroplast ultrastructural traits of two contrasting larch species, fast-growing Larix kaempferi and slowly-growing L. olgensis, grown in larch plantation soil, were investigated during two growth seasons. It was shown that N and combined N and P (NP) fertilization increased plant photosynthesis, foliar N contents, chlorophyll contents, and dry mass accumulation and partitioning in aboveground organs in both larch species. Although P fertilization enhanced P accumulation, its presence reduced the N content in soluble proteins in the foliage of both larch species. Yet, P fertilization exhibited some differences in the two species: P fertilization increased photosynthesis, chlorophyll content and biomass accumulation of L. olgensis, while it decreased these parameters dramatically in L. kaempfert P fertilization increased foliar N content in L. olgensis, while it reduced it in L. kaempferi. P fertilized L. kaempferi had more damaged chloroplast ultrastructure than L. olgensis. In addition, L. kaempferi exhibited lower acid phosphatase activities, and higher photosynthesis and biomass accumulation than L. olgensis, except under P fertilization. L. kaempferi allocated more biomass into needles, except under P fertilization, while L. olgensis allocated more into stems under fertilization. In conclusion, it was shown that nutrient imbalance caused by P fertilization has greater negative effects on a fast-growing species than on a slowly-growing one, and the negative effects are related to differences in acclimation strategies, N partitioning to photosynthetic components, and P transportation and metabolism in the foliage.
  • Song, Mengya; Yu, Lei; Jiang, Yonglei; Korpelainen, Helena; Li, Chunyang (2019)
    The stress gradient hypothesis predicts that plant-plant interactions switch between facilitation (positive) and competition (negative) along environmental gradients, with facilitation being more common under high abiotic stress conditions relative to more moderate abiotic stress conditions. Our aim was to reveal, whether the interactions between Populus purdomii Rehder and Salix rehderiana Schneider switch from positive to negative during the early stages of primary succession in the Gongga Mountain glacier retreat region. We also investigated, whether soil age is a major driving factor for the transformation of interactions between neighboring plants. We analyzed differences between intraspecific interactions and interspecific interactions of Populus and Salix under 20- and 40-year-old soil conditions, including plant biomass accumulation and allocation, nutrient absorption and utilization, relative competition intensity, non-structural carbohydrates, foliar carbon and nitrogen isotope composition, mesophyll cell ultrastructure, soil microbial biomass and community structure, extracellular enzyme activities, and soil organic carbon (SOC), soil total nitrogen (TN), soil ammonium (NH4+-N), and soil nitrate (NO3--N) contents. We found that P. purdomii and S. rehderiana growing under interspecific interactions had greater contents of aboveground dry matter, belowground dry matter and total dry matter compared to intraspecific interactions in 20-year-old soil. Furthermore, in 40-year-old soil conditions, the phospholipid fatty acid (PLFA) analysis showed that Populus and Salix exposed to interspecific interactions exhibited lower amounts of gram-positive bacteria, fungi (18,1 omega 9c) and actinomycetes, and lower levels of total PLFAs than those growing under intraspecific interactions. The redundancy analysis (RDA) results demonstrated that soil N was the most important parameter contributing to the composition of microbial communities. In addition, the N-15 stable isotope labeling method showed that Populus and Salix growing under interspecific interactions had higher foliage delta N-15 derived from NO3- (delta N-15-NO3-) than those growing under intraspecific interactions in 20-year-old soil. In summary, our results demonstrated that Populus-Salix interactions exhibited positive effects on survival in 20-year-old soil. Conversely, under 40-year-old soil conditions, Populus-Salix interactions presented negative effects in relation to nutrients and elimination by neighboring plants. Moreover, soil age is a major driving factor for plant-plant interactions that shift from positive to negative with an increasing soil age in the Gongga Mountain glacier forefield. In all, our results support the stress gradient hypothesis. Our findings improve understanding of plant-plant interactions and plant-soil feedbacks during the early stages of soil development, and of the construction of vegetation communities.
  • Yu, Fei; Yi, Lita; Mao, Xiaoyu; Song, Qi; Korpelainen, Helena; Liu, Meihua (2022)
    Cadmium (Cd) toxicity and nitrogen (N) deposition are two major environmental stresses which can affect plant growth. It's less clear that how the combined Cd accumulation and N deposition affect the male and female plants of dioecious species. The aim of the present study was to detect sex-specific responses to Cd stress and simulated N deposition in one-year-old male, female and hermaphrodite seedlings of Morus alba. Changes in morphology, physiology, root architecture and biomass of the three sex types of mulberry seedlings were determined. The results showed that Cd toxicity caused limited growth, impaired photosynthetic apparatus and decreased gas exchange rates with significant sex-specific differences. Mulberry was found to deploy detoxification mechanisms to avoid or tolerate toxic Cd effects through the activation of the antioxidant system, increasing proline and non-protein thiol contents, translocating Cd into different plant parts and decreasing biomass. Females displayed a low tolerance to high Cd and were more sensitive to Cd stress. Simulated N deposition alleviated the negative effects of Cd on leaves and decreased sex-specific differences in the three kinds of mulberry seedlings, but N fertilizer did not affect the total biomass. The N-stimulated increasing in proline and non-protein thiol contents might play a crucial role in resisting the damage caused by Cd stress, and the three kinds of mulberry seedlings had slightly different ways of improving Cd tolerance by N deposition. Sexual differences in Cd accumulation are correlated with root architecture. This study provides evidence for the utilization of mulberry to treat Cd-contaminated soils under N deposition.
  • Chen, Shengxian; Yi, Lita; Korpelainen, Helena; Yu, Fei; Liu, Meihua (2020)
    Drought stress influences the growth of plants and thus grafting has been widely used to improve tolerance to abiotic stresses. Poplars possess sex-specific responses to drought stress, but how male or female rootstock affect the grafted plant is little known. To explore the mechanisms underlying changes in drought tolerance caused by grafting, we investigated the changes in growth, leaf traits, gas exchange and antioxidant enzyme activities of reciprocally grafted seedlings between Populus euramericana cv. "Nanlin895" (NL-895) (female) and Populus deltiodes cv."3412" (NL-3412) (male) under water deficit stress with 30% field capacity for 30 d. Results showed that drought stress affected adversely growth, morphological, and physiological characteristics in all seedlings studied. Grafted seedlings with male roots can effectively alleviated the inhibition of growth induced by drought stress, as shown by higher WUE, activities of SOD, POD and CAT, and lower levels of lipid peroxidation. Male seedlings with female roots were found to be less tolerance to drought than non-grafted male clones and female scions with male roots, but more tolerance than non-grafted female clones. This results suggested that drought tolerance of grafted seedlings is primarily caused by the rootstock, although the scion also affects the grafted plant. Thus, paying attention on the root genotype can provide an important means of improving the drought tolerance of poplars.