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2024, 37(1)
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2024, 37(1): 1-2.
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Growth Performance of 13 Provenances/Families of Tectona grandis
LI Yun-xing, LIANG Kun-nan, HUANG Gui-Hua, KUANG Bing-chao, HAO Jian, YANG Bao-guo, PAN Li-qin, HUANG Ri-yi
2024, 37(1): 1-9. doi: 10.12403/j.1001-1498.20230005
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Objective In order to select more good varieties with wide adaptability for Tectona grandis, Method The experimental plantation was established with 13 provenances/families collected from Jianfengling and other places in Hainan province. Tree height and diameter at breast height (DBH) were measured at 5, 10 and 37 years old. ANOVA analysis and repeatability assessment were performed to select superior provenances/families. Partial correlation analysis was used to reveal the correlation between tree growth and geographical and climatic factors. Result ①Significant differences among provenances/families were found at 37 years old for survival rate, tree height, DBH and individual volume. The variation ranges were 68.81%~94.29%, 11.72~16.03 m, 11.33~17.92 cm, 0.0844~0.3291 m3, respectively. ② The repeatability of tree height, DBH and individual volume were 0.6077, 0.5131 and 0.6344, respectively. ③ The survival rate and tree height were not significantly correlated with geographic coordinates and climate factors; while DBH and individual volume were significantly positively correlated with elevation (r=0.938**, r=0.868**) and mean annual temperature (r=0.914**, r=0.844**), and negatively correlated with longitude (r=−0.913**, r=−0.735*) and distance (r= −0.923**, r=−0.832**). ④The results of cluster analysis indicated that provenance/family 7514 performed the best on the survival rate, tree height, DBH and individual volume, while 8440 performed the worst, and followed by 75129 at the 37 years old. Conclusion There are significant differences among provenances/families for the survival rate, tree height, DBH and individual volume. Both tree height and individual volume present a relatively high repeatability. For the introduction of teak, it is advisable to choose a source/family with similar annual temperatures and close distances to obtain better genetic performance. For the local area of Pingxiang, source/family 7514 is suitable for widespread planting.
Impacts of Pinewood Nematode Invasion on the Water Conservation Capacity of Pinus massoniana Forests in the Three Gorges Area of Hubei Province
SONG Xue-yu, JIAN ZUN-ji, WANG Shao-bo, DANG Ying-qiao, WEI Ke, WANG Xiao-yi, XIAO Wen-fa
2024, 37(1): 10-20. doi: 10.12403/j.1001-1498.20230113
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Objective To reveal the changing trend of water conservation capacity of litter and soil layers after pinewood nematode invasion. Methods Based on four sites of uniform Pinus massoniana forests with various infection periods over time (0(non-invasion), 6, 10 and 16 years) of pinewood nematode invasion in the Three Gorges Area of Hubei Province, water conservation capacities of litter and soil layer in different forest stands were studied by cutting ring method, drying method and indoor immersion method. The water conservation capacities were also quantitatively compared by combining the effective retention capacity of litters and the effective water-holding capacity of soil in different invasion years. Result The results showed that: (1) There were no significant differences (P>0.05) in the litter accumulation, effective retention and maximum water holding capacity of litter of P. massoniana forest in different invasion years by pinewood nematode, and the total thickness was 3.47~5.34 cm. The total accumulation was 6.11~9.62 t·hm−2, and the effective water retention capacity was 9.71~14.77 t·hm−2. (2) There were significant differences in soil water content, bulk density and non-capillary porosity of P. massoniana forest in different invasion years by pinewood nematode (P<0.05). The capillary water capacity was 333.42~378.33 t·hm−2, and the maximum water-holding capacity was 386.27~461.20 t·hm−2. The effective water-holding capacity (62.08 t·hm−2 and 50.08 t·hm−2) in 0~10 cm and 10~20 cm and maximum water-holding capacity (386.27 t·hm−2) in 10~20 cm soil layers of P. massoniana forest in 6 years of invasion were the smallest. (3) The comprehensive water holding capacity of litter and soil layer in 10 years of invasion (219.72 t·hm−2) was the largest, followed by non-invasion (191.85 t·hm−2), 16 years (182.64 t·hm−2), 6 years (121.86 t·hm−2). Conclusion In the short term, the water holding capacity of litter and soil layer of P. massoniana forest decrease, which affects the water conservation capacity of forest stand after the continuous harm of pinewood nematode invasion in the Three Gorges Area of Hubei, but gradually recover with increasing years. Therefore, the prevention and control of pinewood nematode invasion should be strengthened in the future, to maintain and restore the water conservation function of P. massoniana forest in The Three Gorges Area.
Effects of Aluminum on Stress Resistance Physiology and Root Tip Cell Ultrastructure of Mycorrhizal Seedlings of Pinus massoniana
LIU Hai-yan, LI Kuai-fen, CHEN Hou-ying, DING Gui-jie
2024, 37(1): 21-30. doi: 10.12403/j.1001-1498.20230190
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Objective To provide theoretical basis for the application of ectomycorrhizal fungi in improving the aluminum tolerance of host plants and afforestation, we studied the changes of physiology, root tip cell ultrastructure and subcellular distribution of Al in mycorrhizal / non mycorrhizal seedlings of Pinus massoniana under different Al3+ levels. Method Semi annual mycorrhizal and non mycorrhizal P. massoniana seedlings were treated with 0, 0.2, 0.4 and 0.8 mmol·L−1 Al3+ (AlCl3) respectively by sand culture and pot irrigation with aluminum. We analyzed the changes of antioxidant enzyme activity, MDA content and subcellular distribution of Al in roots, the distribution of ROS and MDA in roots, and the ultrastructure of root tips. Results (1) With the increase of exogenous aluminum concentration, the activities of SOD, CAT, POD and the content of MDA in the roots of mycorrhizal / non mycorrhizal seedlings of masson pine showed an overall upward trend. At high aluminum level (0.8 mmol·L−1), the activities of antioxidant enzymes and the content of MDA were the highest, and the non mycorrhizal seedlings were more affected by aluminum. (2) With the increase of exogenous aluminum concentration, the aluminum content absorbed by root tips of P. massoniana increased significantly, and the aluminum content absorbed by mycorrhizal seedlings was significantly higher than that of non mycorrhizal seedlings. (3) From the cell ultrastructure and subcellular distribution of Al, a large number of Al3+ first combined with the cell wall, and the intracellular Al3+ strongly combined with the biofilm, which strengthened the leakage of organelles and interfered with various regulatory processes of nucleus and mitochondria. Because of the adsorption of aluminum by mycorrhiza, the content of aluminum ions in cells reduced, the structure of subcellular organelles was protected, the basic function of cells was maintained, and the toxicity of aluminum was alleviated. Conclusion The antioxidant enzyme activity and MDA content of root of P. massoniana are increased by aluminum treatment, and aluminum with 0.4 mmol·L−1 produces obvious aluminum toxicity symptoms. Mycorrhizal fungi can reduce aluminum toxicity and improve plant aluminum tolerance by absorbing more aluminum, which is probably an important external resistance mechanism of root seedlings mycorrhiza of P. massoniana.
Deep Learning-based Forest Fire Prediction Model Research in the Daxing'anling Mountains, Inner Mongolia
ZHANG Jin-yu, PENG Dao-li, ZHANG Chao-jun, HE Dan-ni, YANG Can-can
2024, 37(1): 31-40. doi: 10.12403/j.1001-1498.20230195
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Objective To predict forest fires in the Daxing'anling Mountains of Inner Mongolia and provide important support for forest fire prevention. Method Based on the Daxing'anling Mountains of Inner Mongolia as the research object, combined with MCD64 A1 monthly fire point products, terrain, climate and other data, the forest fire potential impact factor data set was constructed, and the convolutional neural network, random forest and support vector machine models were used respectively to predict and visualize the probability of forest fires in the study area. The developed models were evaluated and the spatial distribution characteristics of forest fires were analyzed. Results The main driving factors of forest fire in the Daxing'anling Mountains were altitude, average temperature, total precipitation and the distance from water area in order of importance. The AUC value of CNN, RF and SVM was 0.838, 0.794 and 0.788, respectively, and the accuracy of CNN was the highest. CNN can effectively divide areas with high and low forest fire susceptibility, which is conducive to dividing forest fire warning areas. Conclusion The CNN model is more suitable for predicting the probability of forest fires in the Daxing'anling Mountains than RF and SVM models. The spatial distribution of forest fire risk in the Greater Khingan Mountains is obviously regional, mainly occurring in the southeast region.
Male Reproductive System and Sperm Ultrastructure of the Yunnan Pine Shoot Beetle, Tomicus yunnanensis (Coleoptera: Curculionidae: Scolytinae)
LU Guo-yan, ZHANG Meng-die, ZHANG Yan-lin, YANG Bin, LI Zong-bo
2024, 37(1): 41-51. doi: 10.12403/j.1001-1498.20230135
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Objective Insect reproduction is of vast significance in population processing for the growths and declines in natural or management habitats. Based on the theoretical and practical implications of pest population management, it is essential to gain the male reproductive system and sperm structure of Tomicus yunnanensis (Coleoptera: Curculionidae: Scolytinae), which are the most damaged insects in the Yunnan pine forest in southwest China. Method The male genital system and sperms from newly emerged adults (sexual immaturity) and the precocity of trunk-boring attacks (sexual maturity) of this species are examined structurally using light and transmission electron microscopy. Result The male genital system contains a pair of testes, two twins of tubular accessory glands, a couple of multilobulated accessory glands and seminal vesicles, and deferent ducts connected with a single ejaculatory duct. After sexual immaturity, all genital cysts were only thin transparent tubules, which were milky and gradually thicker after sexual maturity. However, there was orange for the testes and multilobulated accessory glands. Mature sperms were numerous in seminal vesicles currently. Each sperm was filiform in shape, 170.1 ± 39.1 μm in length, and consisted of the head and flagellum. The head was needle-like, with 23.5 ± 3.4 μm in length, and comprised a three-layer acrosomal complex and an inferior cylindrical nucleus. The long flagellum included two mitochondrial derivatives of different sizes, two accessory bodies with a sizeable puff-like expansion, and a classical 9 + 9 + 2 axoneme microtubule pattern. More importantly, the sperm tail showd a high degree of differentiation in the shape of the asymmetrical organelles. Some tail organelles, including puff-like expansion, minor mitochondrial derivatives, accessory bodies, and major mitochondrial derivatives, would gradually disappear toward the end of the sperm. Conclusion . The overall genital characteristics and sperm ultrastructure of the male adults of T. yunnanensis are like those of Curculionidae, which conserve the primitive characters such as three-layer acrosomal complex, 9 + 9 + 2 axoneme and high differentiation of asymmetrical tail organelles. Current results not only enrich the taxonomic and phylogenetic studies of the subfamily Scolytinae, but also help us further understand the physiological attributes in insemination specificity of Tomicus yunnanensis.
Carbon, Nitrogen and Phosphorus Release and Their Stoichiometric Ratio Change During Decomposition of Cunninghamia lanceolata Leaf Litter at Different Temperatures
ZOU Zhi-guang, ZHANG Ma-xiao, HUANG Xiao-yan, ZHANG Xin-yang, LI Shu-bin, ZHOU Li-li
2024, 37(1): 52-62. doi: 10.12403/j.1001-1498.20230230
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Objective To explore the effects of rising temperature on the release of carbon (C), nitrogen (N) and phosphorus (P) during leaf litter decomposition of Chinese fir at different developmental stages and their stoichiometric variations under the scenarios of climate warming. Methods The leaf litter of Chinese fir at three developmental stages, i.e. middle-aged forest (18-years old), mature forest (30-years old) and overmature forest (42-years old), was collected for decomposition experiments at three temperature treatments (i.e., 25, 30 and 35 ℃). Results (1) During the 264-day decomposition period, the residual rates of C, N and P in leaf litter at each development stage generally decreased over time. The residual rates of C, N and P showed patterns with release-enrichment-release, release-release, and release-enrichment, respectively. (2) The results of Olson fitting model revealed that the N turnover time of mature forest and over-mature forests during litter decomposition was shortened by 34.4 and 16.9%, respectively under 35 ℃ compared with 25 ℃. In comparison, the P turnover time was shortened by 38.4% and 43.8%, respectively. (3) During litter decomposition, the ratios of C∶N and N∶P generally fluctuated, and C∶P increased first and then decreased. The variation of C∶N, C∶P and N∶P ratios were 9.32-39.0, 949-2 194 and 32.7-153, respectively. In the decomposition process of leaf litter, rising temperature increased C∶P, N∶P, and decreased C∶N. Conclusion Rising temperature can shorten the turnover rate of N and P during litter decomposition in mature and overmature forests by increasing C∶P and N∶P ratios during litter decomposition, indicating that litter decomposition of Chinese fir is obviously limited by P. It is suggested to appropriately increase the application of P fertilizer according to the growth needs of Chinese fir at different developmental stages.
Soil Carbon Changes and Its Influencing Factors in Major Forest Types in the Subtropical Area of Yunnan Province
ZHAO Qiao-qiao, ZHAO Xiao-qing, HUANG Pei, PU Jun-wei, ZHOU Shi-jie, FENG Yan, GU Ze-xian, SHI Xiao-qian, CHU Bo-cheng
2024, 37(1): 63-72. doi: 10.12403/j.1001-1498.20230044
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Objective As the largest carbon pool in terrestrial ecosystems, changes in forest soil organic carbon (SOC) have a significant impact on the global carbon cycle. By exploring the differences in SOC in different forest types and its influencing factors, we aim to provide a theoretical basis for forest carbon sink management. Method Eucalyptus plantation forest (EP), Pinus pure forest (PK) and evergreen broadleaf forest (EB) in Lancang County were used in this study. ANOVA and redundancy analysis were used to analyze SOC, soil organic carbon density (SOCD) and carbon to nitrogen ratio (C/N) levels and vertical distribution patterns of the three forest land types at different depths of 0~20 cm, 20~40 cm and 40~60cm and reveal their main influencing factors. Result (1) There were significant differences in SOC among the three forest types in the 0-60 cm soil layer. Its variation range was 14.89~22.05 g·kg−1, which was higher than the national forest soil organic carbon level, with EB forest having the highest (22.05 g·kg−1); The SOCD ranged from 3.42 to 4.12 kg·m−2, with the highest in EB forests (4.12 kg·m−2); The soil C/N ranged from 12.99 to 13.82, with EP forests being the highest (13.82); (2) As the soil layer deepens, the SOC, SOCD, and C/N of the three types of forest land showed a downward trend, with the EB soil organic carbon content and density showing the most obvious downward trend; (3) The organic carbon content and density of the three types of forest land were mainly affected by soil density, organic matter, total nitrogen, hydrolytic nitrogen, and total phosphorus, with little impact from environmental and topographical factors; The main influencing factors of soil C/N were organic matter, pH, and aspect, while environmental factors had a relatively small impact on it. Conclusion The soil of EP and EB have advantages in carbon sink, while the carbon sink function of PK is weaker. Soil carbon content is more influenced by soil physicochemical indexes and less influenced by environmental and topographic factors.
Effect of Vegetation Configuration in Riparian Buffer Strip on Phosphorus Retention in Runoff Water
HUANG Sai-feng, WU Yong-bo, MAO An-min
2024, 37(1): 73-81. doi: 10.12403/j.1001-1498.20230239
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Objective To study the effect of different buffer strips on phosphorus retention in runoff, and provide reference for the selection of suitable buffer zones and effective control of eutrophication in Taihu Lake. Methods Seven riparian buffer strips of 20 m x 40 m in Taihu Lake area were used to compare the effects of riparian buffer strips with different widths (15, 30 and 40 m), different vegetation types (Populus × euramericana ‘Nanlin 95’ plantation, Taxodium ‘Zhongshanshan’ plantation, and ‘Nanlin 95’ - ‘Zhongshanshan’ mixed plantation) and different stand densities (400, 1,000 and 1,600 tree·hm−2) on the retention of total phosphorus (TP) and soluble phosphorus (DP) in runoff water. Results (1) The interception of TP and DP in runoff water was significantly better in winter than in spring. The retention rate of DP in runoff water was significantly higher than that of TP in the buffer strips. (2) Different riparian buffer strips had different requirements for width. For Taxodium ‘Zhongshanshan’ forest, mixed forest, and poplar forest of 400 and 1000 tree·hm−2, a 15m wide riparian buffer strip could basically meet the demand for phosphorus intercept. For the poplar forests with 1600 tree·hm−2, a riparian buffer zone of more than 40 m width was required to meet the phosphorus retention requirement. (3) For the buffer zone of Taxodium ‘Zhongshanshan’ forest and poplar forest, the buffer strip with a stand density of 400 tree·hm−2 had the best effect on the retention of TP and DP in runoff water. (4) The interception effect of Taxodium ‘Zhongshanshan’ forest buffer zone on phosphorus in runoff was better than that of mixed forest and poplar forest buffer zone, and Taxodium ‘Zhongshanshan’ could be used as the first choice for constructing riparian buffer strips in Taihu Lake. Conclusion The Taxodium ‘Zhongshanshan’ forest buffer strip with a width of 15 m and 400 tree·hm−2 can achieve the maximum effect on phosphorus retention in runoff.
Soil Physicochemical Properties and Dynamic Changes of Understory Plant Diversity at Different Growth and Development Stages of Eucalyptus urophylla × Eucalyptus grandis Plantation
LU Hai-fei, XU Jian-min, LI Guang-you, MA Ning, SU Guo-lei, ZHANG yun-dong
2024, 37(1): 82-91. doi: 10.12403/j.1001-1498.20230303
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Objective To study the growth status, soil physical and chemical properties and understory plant diversity of Eucalyptus urophylla × Eucalyptus grandis pulpwood plantation of different age groups in southern Yunnan for providing theoretical basis for sustainable management of eucalyptus pulpwood plantation. Method In this study, 106 plots of red soil or red soil developed from coarse-grained crystalline rocks, muddy rocks, and carbonate rocks, with similar site conditions at an altitude of 1400~1700 meters, belonging to 5 different age groups. The differences in growth indicators, soil factors, and plant diversity indices among different age groups were analyzed through variance, multiple comparisons, and redundancy analysis. Correlation analysis was also used to reveal the correlation between them. Result The height, DBH and living wood growing stock of E. urophylla × E. grandis plantation in different age groups increased with the growth of the stand. The growth rate was faster in the middle-aged forest, but slowed down in the mature forest (7-8a). There were significant differences in soil porosity and soil moisture content among different age groups, and the overall trend showed an increase and then a decrease with the growth of the stand, reaching the highest value in the near mature forest. There were significant differences in soil total nitrogen among different age groups, and the growth of tree height, diameter at breast height, and stand volume were significantly correlated with total nitrogen. The richness index and evenness index of herbaceous and total shrubland under the Eucalyptus urophylla forest were positively correlated with soil organic matter and available zinc. The richness index of shrubs was positively correlated with soil moisture, available nitrogen, and available copper. The Shannon Wiener index of herbs and shrubs was positively correlated with soil total nitrogen, while it was significantly negatively correlated with soil bulk density and pH value. The evenness index of shrub Pielou was positively correlated with soil total potassium. Among them, soil organic matter had the greatest impact on the understory vegetation diversity of Eucalyptus urophyllus, with the variance accounting for 18.3% (F=13.21, P<0.05). Conclusion There is a competitive relationship between the growth of young E. urophylla × E. grandis plantation and herbaceous plants. The influence of plant diversity on soil structure and physical properties is greater than that of chemical properties. At near maturity, the total shrub and shrub biodiversity reaches the maximum, which reveals that the eucalyptus plantation ecosystem enters self-restoring succession after near maturity.
The Influence of Planting Patterns and Mycorrhizal Types on Absorptive Root Traits
LIANG Jia-fang, REN Xin-hua, XIA Lei, LIU Bi-tao
2024, 37(1): 92-101. doi: 10.12403/j.1001-1498.20230125
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Objective The effects of planting methods and the mycorrhizal types on absorptive root traits of tree species were analyzed to reveal the adaptive conditions for species coexistence. Methods In this study, monoculture and mixture of 8 species (5 AM and 3 EM) were selected. The main morphological traits (root diameter, specific root length, root tissue density, individual root length) and architectural traits (root branching intensity, root branching ratio strength) and mycorrhizal colonization of absorptive roots (first two order roots) of two types of mycorrhizal tree species (AM vs EM) under two planting patterns (monoculture vs mixture) were analyzed. Results Mycorrhiza significantly affected morphological and architectural traits of absorptive roots (p<0.001), and significantly affected mycorrhizal colonization(p<0.05); while planting patterns only significantly affected root tissue density and root architectural traits (p<0.05); mycorrhizal types and planting patterns had no interaction on all root traits (p>0.05). The correlation between root traits of AM species was higher than that of EM species, and the mixture greatly reduced correlations between root traits of AM tree species. For AM species, the mixture reduced the plasticity of root morphological traits (except for specific root length) and increased the plasticity of architectural traits. For EM species, the mixture reduced the plasticity of root tissue density, and increased the plasticity of root diameter, architectural traits and mycorrhizal colonization. Conclusion There are significant differences in root morphological and architectural traits between AM and EM species. Mixed forests mode has varying degrees of effects on the plasticity of root traits of AM and EM species, mainly increasing the branching intensity of AM species and decreasing the root tissue density of EM species. Therefore, different mycorrhizal species can achieve species coexistence by regulating different root trait changes.
Effects of Different Ecological Groups of Earthworms on the Distribution of Litter into Aggregates
ZHANG Xue-lian, GU Yu-chen, WANG Guo-bing
2024, 37(1): 102-109. doi: 10.12403/j.1001-1498.20230118
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Objective By studying the transformation and distribution patterns of litter-derived carbon in soil under the action of different ecotypes of earthworms, providing theoretical basis and data support for exploration of the impact of earthworms on the carbon sequestration and sink enhancement potential of soil in poplar plantations. Methods The leaves of poplar seedlings enriched with 13C were marked by pulse labeling method. Three different ecotypes of earthworms were inoculated to study the distribution of litter source carbon in water-stable aggregates of coarse aggregates (d>2 mm), fine aggregates (2≥d>0.25 mm), microaggregates (0.25≥d>0.053 mm) and silt-clay aggregates (d≤0.053 mm) under the action of different ecotypes of earthworms. Results After inoculation of earthworms, the incorporation and distribution of litter source carbon into the soil were significantly promoted, and the soil δ13C value was significantly increased. The enhancement range of epigeic earthworms was the lowest, in contrast, that of epi-endogeic and anecic types was the highest. The δ13C values of soil water stable aggregates of different particle sizes increased significantly under the action of earthworms. The δ13C values of four kinds of soil aggregates were the lowest in silt-clay aggregates, and the highest in coarse aggregates and fine aggregates. The effect of Eisenia foetida on the incorporation of litter into soil aggregates was lower than that of Amynthas corticis and Pheretima guillelmi. Conclusion After 120 days of short-term culture, different ecotypes of earthworms significantly promotes the incorporation and distribution of litter-derived carbon into the soil, and significantly increases the accumulation of litter source carbon in coarse aggregates and fine aggregates. With the participation of epi-endogeic and anecic types, the distribution of carbon to aggregates from litter is significantly increased. We suggest that the application of forest litter residues should be appropriately increased in the process of forestry production and management, and the cooperation and competition among different ecotypes of earthworms should be taken into account. Multiple types of earthworms should be inoculated to improve or enhance the potential of earthworms to regulate soil organic carbon (SOC) dynamics in the forestry ecosystem, accelerating the incorporation and distribution of exogenous organic matter into the soil.
Relationships between Crown Structure and Crowding in Quercus mongolica Forest of Xiaolong Mountains under Different Stand Densities
JIANG Meng-duo, MA Ying-dong, JIANG Rui, LI Ping-ying, BAO Yong-ping
2024, 37(1): 110-118. doi: 10.12403/j.1001-1498.20230140
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Objective This study explores the relationships between stand density, crown structure and crowding, in order to deeply clarify the structural characteristics of Quercus mongolica secondary forest for providing sufficient scientific basis for sustainable forest management in the future. Method In August 2020,typical plots with similar site conditions and different stand densities were selected from the secondary mixed forest of Quercus mongolicus in Xiaolong Mountains to analyze the relationship between crown structure and crowding under different stand densities by using Pearson correlation analysis and structural equation model. Result There were differences in the crown structure characteristics of Quercus mongolicus forest with different stand densities. The variation in crown volume was the strongest, followed by crown length and crown area. The variation in crown width, crown length ratio and crown shape ratio was the weakest. The variation trend in crown structure characteristics showed a unimodal distribution with changes in stand density. With the decrease of stand density, the correlation trends of crown width, crown area and crown volume with DBH were similar to "L" pattern, while the correlation between crown length and DBH were consistent with the change in stand density, and the effects of stand density on the correlation between crown length rate, crown shape rate and DBH was not significant. The crowding of the Quercus mongolica forest ranged from medium dense to very dense, but the crowding in different density stands was different. The dominant species of Quercus mongolica, Betula platyphylla, Pinus armandii and Tilia tuan dominated the crowding. The influence of stand density on the relationship between crown structure and crowding in Quercus mongolicus forest could be divided into two ways: forest competition - indirect effects mediated by crown structure; The indirect impact mediated by forest competition, diameter at breast height, and crown structure. Conclusion The crown structures of Quercus mongolica forest vary with different stand densities. Crown structure is related to the DBH. The relationship between crown structure and crowding of Quercus mongolicus forest is finally affected by stand density. In order to achieve sustainable management of the Quercus mongolicus secondary forest, we should not only consider the DBH, but also pay attention to the characteristics of the crown structure. By adjusting stand density, we can optimize the crown structure and improve the crowding state to promote forest regeneration and increase species diversity.
Diameter Growth Models of Picea crassifolia from Different Habitats in Qinghai Province
MA Hao, CHEN Ke-yi, XU Gan-jun, DANG Yu-jie, HE You-jun, WANG Jian-jun
2024, 37(1): 119-129. doi: 10.12403/j.1001-1498.20230097
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Objective The growth regularity and diameter at breast height (DBH) growth model of Picea crassifolia from different habitats were studied, which will provide empirical models and reference basis for forest protection and management. Method Base on the tree-ring data of Picea crassifolia in Qinghai province, the increment of tree DBH was used to analyze tree growth in different habitats. Then, five kinds of individual-tree growth models were constructed, and compared according to the model goodness of fit andindexes. Finally, origin and slope position effects were considered to develop mixed effects models, and the evaluation indices of different models were used. Result When trees grew to breast height, the increment of individual trees decreased with age and then changed gently. The fast-growing period of Picea crassifolia natural forests and plantations was 29—44 a and 29—39 a, respectively. The current annual increment of DBH (CAI) and mean annual increment of DBH (MAI) of natural Picea crassifolia were above 0.40 cm. CAI and MAI of of natural forests changed slowly, while the trees growth of plantations had relatively large variation ranges. The trend of DBH increment of Picea crassifolia were different among four slope positions. The results of optimal individual-tree growth models developed along different habitats showed that the determination coefficients (R2) were above 0.913, the total relative error (TRE) and the average system error (MSE) were within ± 2%, the average prediction errors (MPE) were less than 5% mostly, and the average percentage standard errors (MPSE) were less than 35%. Based on the Gompertz model, the R2 of mixed effects model was 0.702, the TRE, MSE, MPE and MPSE of mixed effect model were 0.03%, −0.30%, 4.23% and 29.54%, respectively, decreased by 89.3%, 83.5%, 20.6% and 15.1% compared with that of based model. Conclusion The growth patterns of Picea crassifolia are different under different habitats. The Picea crassifolia of natural forests have a longer vigorous growing period than that plantations. The mixed effect model of individual-tree growth of DBH considering the different habitats, can be used to estimate the changes of DBH for Picea crassifolia in Qinghai province.
Effects of Two Walnut Aphids on Photosynthetic Characteristics of Walnut
ZHANG Wen-jia, MA Gui-long, GAO Gui-zhen
2024, 37(1): 130-139. doi: 10.12403/j.1001-1498.20230346
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Objective To investigate the impacts of two aphid species, Chromaphis juglandicola Kaltenbach and Panaphis juglandis Goetze on photosynthesis of walnut. Method During the rapid growth, hard core, and fatty stages of walnuts, the portable chlorophyll analyzer (SPAD-502plus) and LI-6400 portable photosynthesis system were used to measure the SPAD value, photosynthetic rate (Pn), transpiration rate (Tr), and other photosynthetic characteristics of the leaves of walnuts that were damaged by different walnut aphids. The fruit weight and kernel yield of walnuts were also measured after being damaged by different walnut aphids. Result There was no significant difference in the SPAD value of walnut leaves when exposed to short-term damage by P. juglandis or C. juglandicola for 1-5 days. However, during the hard core and lipid stage, exposure to the P. juglandis, C. juglandicola, and mixed aphid led to a downward trend in the SPAD value of leaves. The photosynthetic rate (Pn) and transpiration rate (Tr) of walnut leaves significantly decreased after being damaged by two types of walnut aphids, and the degree of decline varied with different density of aphids. The fresh fruit weight and dried fruit weight of walnuts showed a decreasing trend after being damaged by P. juglandis and C. juglandicola. The walnut kernel yield decreased after being affected by different types of aphids. Conclusion The walnut aphids has a negative impact on the normal photosynthetic process of the leaves, leading to a decline in the kernel percentage of walnut fruits. Therefore, urgent measures should be taken to control both walnut aphid species in order to protect walnut yield and quality.
Correlation Analysis between Physiological Scorch and Mineral Elemental Contents in Walnut Leaves
WANG Xia-lei, LIANG Xin-miao, LIU Jia-le, JIA Peng, CHEN Li-ying, QI Guo-hui
2024, 37(1): 140-149. doi: 10.12403/j.1001-1498.20230158
Abstract:
Objective In this study, the mineral elements and other indicators of walnut leaves were measured and analyzed by the method of leaf nutrition diagnosis, in order to determine the causes of walnut leaf scorching, and then provide a theoretical basis for walnut production, cultivation and management. Methods Walnut trees were graded according to the degree of leaf scorch, the contents of mineral elements (N, P, K, Na, Ca, Mg, Fe, Mn, Cu, Zn, B) and chlorophyll in walnut leaves at different scorch degrees and at different periods were measured. And analyze the correlation among mineral elements, and between mineral elements and scorch degree. Results The results showed that the contents of photosynthetic pigment in leaves decreased with the increase of scorching degree. The scorching phenomenon developed from the edge to the middle part of the leaves. The degree of illness was significantly positively correlated with N content (R=0.63), significantly positively correlated with P content (R=0.76), and significantly negatively correlated with Mn and B content, with correlation coefficients of -0.73 and -0.91, respectively. The parameter estimated of the content of B in the Logistic regression was -0.872 (p<0.05), indicating that B content had a significant negative impact on the degree of scorch. And after spraying different concentrations of B fertilizer, the symptoms of scorching and withering were effectively alleviated. Conclusion Lack of B is the main reason for the scorching of ‘Lyuling’ walnut leaves.
Floral Morphology and Development of Female and Male Gametophytes of Bambusa textilis
YAN Ying-dan, ZHOU Li, WANG Shu-guang
2024, 37(1): 150-158. doi: 10.12403/j.1001-1498.20230222
Abstract:
Objective In order to clarify the morphological and anatomical characteristics of floral organs and male and female gametophytes at different developmental stages of Bambusa textilis under natural conditions. Method The appearance morphology of each part of floral organs and the development process of male and female gametophytes were observed and described by means of morphology and anatomy, and sectioning techniques. Results The spikelets of B. textilis had infinite inflorescences, and the florets in the lower part of the spikelets developed first. However, due to the latent buds at the base of the spikelets, they also had the characteristics of definite inflorescence. There were about 8-10 florets in each spikelet with the sterile floret on the top and 2-3 yellow-brown bracts at the base. Each floret contained 1 palea, 1 lemma, 6 stamens, 3 lodicules and 1 pistil. The florets of B. textilis were dichogamy, cross-pollination. The ovary was vase-shaped, and the lower part was smooth without prismatic protrusions and the upper part was unilocular and lateral membranous with an anatropous ovule. The stigmas were three-lobed and feathery. The anther of B. textilis was yellow with four sporangias, and the anther wall was composed of four layers, epidermis, endothecium, middle layer and tapetum from outside to inside. The tapetum was glandular. The tapetum degenerated, leaving only two layers of epidermis and fibrous layer after anther maturation. The mature pollen grains have 2 or 3 nuclei, and the pollen grains are longitudinally dispersed after maturation. Conclusion The morphological structure of B. textilis floral organs is normal, while various abortions occur during the development of female and male gametophytes, which may be an important reason for the low seed setting rate.
Comprehensive Evaluation of Suitable Land and Tree Varieties of Acacia melanoxylon Family
ZHAO Yue-qiao, HUANG Xiao-xia, ZHANG Lu-yue, GAO Wen-jing, CHENG Nuo, DING Guo-chang, LAI Ri-wen
2024, 37(1): 159-170. doi: 10.12403/j.1001-1498.20230188
Abstract:
Objective To select suitable Acacia melanoxylon lines in southern mountains and to reveal the relationship between the spatial variation pattern of soil nutrients and topographic changes in Acacia melanoxylon growth. Method In this paper, based on seven 15-year-old Acacia melanoxylon lines (M1~M7) created on cedar logging sites , classical statistics, descriptive statistics, geostatistical methods and GIS technology were used to study the variation patterns of soil physical and chemical properties and spatial distribution of soil nutrients of seven Acacia melanoxylon lines at different slope positions. The seven Acacia melanoxylon lines were evaluated and selected by factor analysis and fuzzy evaluation method. Result The physical and chemical properties of the seven Acacia melanoxylon lineages in the lower slope were the largest, followed by middle slope and upper slope, and those in the lower slope was significantly higher than those in the other slopes; the soil structure and nutrient contents in the M7 stands in were the best, followed by M6 and M5; the nutrient contents in the study area were generally distributed in blocks or strips, showing an increasing trend from northeast and northwest to south. Conclusion The comprehensive evaluation value is the highest in the upper and lower slope of Acacia melanoxylon family M7, and its growth has the best effect on the improvement of soil physical and chemical properties, and in the middle slope of Acacia melanoxylon family M6. The results of the study are of reference value for the study of land-appropriate species and sustainable development in southern mountainous areas, and can be used in the management practice of Acacia melanoxylon plantations.
Dynamics in Niche and Interspecific Association of Dominant Species in Natural Secondary Forest of Xingdou Mountain
HE Jiang, XU Lai-xian, AI Xun-ru
2024, 37(1): 171-182. doi: 10.12403/j.1001-1498.20230108
Abstract:
Objective The evergreen-deciduous broadleaved mixed forest is a unique natural forest type in China, as the main vegetation type in the subtropical mountains. The niche and interspecific association dynamics of dominant species in typical subtropical evergreen-deciduous broadleaved mixed forest are explored to elucidate the adaptive capacity, interspecific relationships and change patterns of dominant species in short-term community development, and also to provide a theoretical basis for biological resource conservation, restoration and forest management in subtropical regions. Method Based on the natural secondary forest in Hubei Xingdoushan National Nature Reserve, combined with the survey and monitoring data of 48 fixed plots in 2013 and 2018, the dynamic changes of niche breadth, niche overlap index, variance ratio method, χ2 test, association coefficient, Jaccard index and Spearman rank correlation coefficient of the top 10 dominant species (importance value greater than 2%) were analyzed. Result (1) There were smaller changes in species composition in 2013 and 2018, with a decrease in the number of species, families and genera. Only one of the top 10 dominant species in terms of species importance value changed. (2) The two surveys showed that the niche overlap index was mainly between 0.2 and 0.5, and the number of species pairs increased with the development of the community. With the development of the community, the niche overlap degree, niche breadth and resource utilization ability of most dominant species decreased gradually. (3) Over the past 5 years, the importance ranking and niche width ranking were not exactly the same, and community resources were not fully utilized. Sorbus alnifolia and Eurya alata have always dominated the ecological niche overlap index with other dominant species, showing a stable or increasing trend. (4) The overall association of dominant species in the two surveys was significantly positive. The results of χ2 test, association coefficient, Jaccard index and Spearman rank correlation coefficient for the 10 dominant species in the two surveys were generally consistent. The number of positively associated species pairs was greater than that of negatively associated species pairs, and the number of extremely significant or significantly positively associated species pairs was greater than that of extremely significant or significantly negatively associated species pairs. The pairs of non-significant associated species also accounted for an important proportion. Moreover, with the development of the community, the significant positive correlation of the overall association gradually increased, the number of positively correlated pairs and the ratio of positive to negative correlations gradually increased, and the number of negatively correlated pairs gradually decreased. Conclusion The natural secondary forests in Hubei Xindushan National Nature Reserve are in the early to middle stages of natural succession, and interspecific associations are loose and not tight. Among them, S. alnifolia and E. alata are highly competitive, and the evergreen species of Rhododendron stamineum, Quercus multinervis and Lithocarpus cleistocarpus are increasing their ability to utilize environmental resources.
Soil Enzyme Activities and Ecological Stoichiometric Characteristics under Two Coverage of Dicranopteris dichoyoma in Phyllostachys edulis Forest
DONG Guo-xin, HUANG Xue-man, WANG Yi, REN Li-ning
2024, 37(1): 183-193. doi: 10.12403/j.1001-1498.20230137
Abstract:
Objective To explore the effects of different coverage of Dicranopteris dichoyoma on soil enzyme activities and ecological stoichiometric characteristics in Phyllostachys edulis forest. Method The content of soil organic carbon (C), total nitrogen (N), total phosphorus (P), soil enzyme activities involved in soil C, N, and P cycling, soil enzyme ecological stoichiometric characteristics (EC:N:P) and microbial biomass of different groups in soil aggregates were measured in moso bamboo forests with low Dicranopteris dichoyoma coverage (PE: 7.75%) and high Dicranopteris dichoyoma coverage (DD: 63.25%), respectively. Results (1) There was no significant difference in β-glucosidase and N-acetyl-glucosaminidase activities between PE and DD sites. The activities of Leucine-amino-peptidase, acid phosphatase and phenoloxidase significantly increased, but the activity of peroxidase significantly decreased in DD site, compared to PE site, which mainly occurred in large and small marcroaggregates. (2) There was no significant difference in EC:N and EN:P between different soil aggregates in PE site, but EC:N in microaggregate was significantly higher than that in large and small marcroaggregates, while EN:P in microaggregate was significantly lower than that in large and small marcroaggregates in DD site. The EC:N:P in large and small marcroaggregates in DD site equaled to that in PE site, but compare to PE site, the EN:P and EC:P in microaggregate significantly decreased in DD site. (3) In addition to arbuscular mycorrhizal fungi and actinomycetes regulating the variation of soil enzyme activities in PE and DD sites, soil total phosphorus content (TP) is also a major factor affecting the variation of enzyme activities in DD site. Soil total nitrogen content (TN) and TP were important factors in regulating the variation of soil enzyme activities in large and small marcroaggregates, respectively, and the variation of soil enzyme activity in large marcroaggregate was also affected by fungal biomass. Conclusion The responses of soil enzyme activities in different soil aggregates and ecological stoichiometric characteristics vary with the coverage of Dicranopteris dichoyoma population in Phyllostachys edulis forest, and the moso bamboo ecosystem is co-limited by both C and P, but the P restriction is more stronger, and the limited effect is exacerbated under high coverage of Dicranopteris dichoyom population in the study area.
The Damage Regularity of Monochamus alternatus in Qinshui County, Shanxi Province
GAO Rui-he, LIU Jia-qi, LIU Lei, FAN Shi-ming, CUI Hao, DONG Xiao-jiao, LIU Yan, ZHANG Zhi-wei
2024, 37(1): 194-202. doi: 10.12403/j.1001-1498.20230228
Abstract:
Objective The aim of this study was to clarify the damage characteristics and occurrence regularity of Monochamus alternatus in Qinshui County Shanxi Province, and to provide theoretical and scientific basis for effectively preventing and controlling the further spread of M. alternatus and the invasion of Bursaphelenchus xylophilus in Shanxi Province. Method From 2019 to 2022, the dynamic monitoring method was used to monitor the population dynamics of M. alternatus adults by hanging traps for four years, and the morphological characteristics of adults were analyzed. Combined with the “law of total effective accumulated temperature” and meteorological data, the generations of M. alternatus in Qinshui County Shanxi Province was calculated. A total of 24 standard plots were established, and the damage of M. alternatus to the tree species in the plots was investigated. At the same time, 36 dead P. bungeana trees were selected for stumpage dissection to clarify the occurrence and damage of M. alternatus on the host tree. Result There were significant differences in the five indexes of elytra length, antenna length, antenna length/body length, tibia length and femur length between male and female adults of M. alternatus in Qinshui County Shanxi Province. The ratio of antenna length to body length of M. alternatus adults could be used as a morphological index for sex determination of M. alternatus in Shanxi Province. The generation of M. alternatus in Qinshui County Shanxi Province was about 1 generation per year. The occurrence period of M. alternatus adults was about from late May to early October. The beginning period was late May, the peak period of emergence was from mid-June to mid-July, the peak period was mid-July, and the end period is early October. In Qinshui County Shanxi Province, M. alternatus mainly damaged P. bungeana trees with a diameter of 2.50-17.50 cm. The larvae were mainly distributed at 0-1 m (41.54%) of the trunk, and the elusion holes were mainly concentrated in 1-2 m (28.62%) of the trunk. Conclusion The generation of M. alternatus in Qinshui County Shanxi Province is about 1 generation per year, and the morphological characteristics of male and female adults are significantly different. The occurrence period of adult is from late May to early October, and the peak emergence period is mainly from mid-June to mid-late July. M. alternatus is mainly harmful to P. bungeana in Qinshui County Shanxi Province. The density of larvae and the number of elusion holes are mainly concentrated in the range of 0-2 m.
Embryonic Development and Egg Diapause Stage of Bamboo Locust Ceracris kiangsu Tsai
WANG Mei, FANG Zeng-hong, FENG Jia-de, FENG Dan, XIE Chun-hua, WEN Yi-fu, CHEN Peng
2024, 37(1): 203-210. doi: 10.12403/j.1001-1498.20230032
Abstract:
Objective To explore the characteristics and duration of the embryonic development of Ceracris kiangsu Tsai and the occurrence stage of its egg diapause. Method The embryo morphology and development period of C. kiangsu at different developmental stages were observed by stereomicroscope, and the water content of eggs, the full length, antennal length and head size of the embryo of C. kiangsu at different developmental stages of the eggs were measured. Results Under constant temperature of 25 °C, the embryonic development of C. kiangsu could be divided into 10 stages : stage I ( 2-5 d ), stage II ( 6-9 d ), stage III ( 10-16 d ), stage IV ( 17-24 d ), stage V ( 25-32 d ), stage VI ( 33-75 d ), stage VII ( 76-85 d ), stage VIII ( 86-92 d ), stage IX ( 93-100 d ) and stage X ( 101-109 d ). Embryonic development could be divided into four developmental stages: stage I and stage II were the initial development stage of embryos, stage III and stage IV were the rapid development stage of embryos, stage V-VII was the slow development stage, and stage VIII-X was the recovery development stage. After fourty-five days of oviposition, eggs entered the diapause development, and egg diapause occurred at stage VI. Conclusion This study clarifies the embryonic development period and the embryonic development stage of egg diapause in C. kiangsu, and provides data support for clarifying the mechanism of the egg diapause of C. kiangsu.