Differential responses of photosynthetic parameters in saplings and adult trees to nitrogen and phosphorus addition in an evergreen broad-leaved forest

The canopy structures and light conditions and the population characteristics of Fargesia decurvata, a dominant understory species, were investigated in three typical communities, i.e., deciduous broad-leaved forest, evergreen and deciduous broad-leaved mixed forest, evergreen broad-leaved forest. The results showed that with the succession from deciduous broad-leaved forest to evergreen and deciduous broad-leaved mixed forest and to evergreen broad-leaved forest, the Shannon index, Simpson index and Pielou index were increased, suggesting that the development of communities in Jinfo Mountains tended to be stable. Moreover, canopy structures were significantly changed, in that the canopy openness and mean leaf angle decreased, leaf area index increased, and canopy extinction ability enhanced, resulting in the decrease of light intensity under the canopy. The upper canopy was the main contributor for canopy closure, with the crown depth and crown area of canopy being the two main influencing factors. Moreover, canopy structures were significantly correlated with light conditions in the forest, with the greatest influence on the diffuse solar radiation. With the growth season coming, canopy openness and understory light conditions were decreased, while leaf area index increased, and their maximum values appeared in June or July in the three forest types. The maximum and minimum value of mean leaf angle appeared in spring and summer, respectively. Clonal growth of F. decurvata was closely related to canopy structures and light conditions. In evergreen and deciduous broad-leaved mixed forest with moderate light, F. decurvata grew best, with high and thick ramets, high ramet density (29.69±1.68 ind·m-2) and high ability to expand rhizomes. In deciduous broad-leaved forest, the strong light condition caused the reduction of soil water might have effects on the growth of F. decurvata. However, in the evergreen broad-leaved forest with low light condition, ramets of F. decurvata tended to be short and thin, with low ramet density (5.80±1.16 ind·m-2) and the clonal expansion ability. Those results suggested that forest succession would change canopy structures and understory light conditions. Low understory light conditions prohibited the regeneration and development of F. decurvata population.

Aims: Pinus yunnanesis is commercially, culturally and economically important, but there is a lack of ecological data on its role in stand dynamics. Our aims are to clarify the structure, composition, regeneration and growth trends of primary mature P. yunnanensis forests. Study area: The Tianchi National Nature Reserve in the Xuepan Mountains, Yunlong County, northwestern Yunnan, China. Methods: We investigated forests containing P. yunnanensis, measured tree ages and analyzed the data. Results: Six forest types were identified: (1) coniferous forest: Pinus yunnanensis (Type 1); (2) mixed coniferous and evergreen broad-leaved forest: P. yunnanensis-Lithocarpus variolosus (Type 2); (3) mixed coniferous and deciduous broad-leaved forest: P. yunnanensis-Quercus griffithii (Type 3); (4) mixed evergreen broad-leaved and coniferous forest: Castanopsis orthacantha-P. yunnanensis-Schima argentea (Type 4); (5) mixed coniferous, evergreen and deciduous broad-leaved forest: Pinus yunnanensis-Schima argentea-Quercus griffithii (Type 5); (6) mixed coniferous and evergreen broad-leaved forest: Pinus armandii-Quercus rehderiana-Pinus yunnanensis (Type 6). The size- and age-structure and regeneration patterns of P. yunnanensis were highly variable within these six forest types. P. yunnanensis regeneration was well balanced in forest Type 1 as compared to the other five types. All six forest types were identified as rare and old-growth with P. yunnaensis trees reaching ages of more than 105 years (a maximum age of 165 years with a diameter 116 cm at breast height) except for the Type 4 forest (a 90-year-old stand). Growth rates of P. yunnanensis, based upon ring width measurements, were high for the first 10 years, then declined after the 10th year. In contrast, basal area increment (BAI) increased for the first 25 years, plateaued, and only declined as trees became older. Trees in the older age classes grew more quickly than younger trees at the same age, a consequence of either site quality or competitive differences. The BAI of P. yunnanensis in all age classes in the Tianchi National Nature Reserve was much higher than those of the secondary and degraded natural P. yunnanensis forests of other areas. Conclusions: The P. yunnanensis forests of the Tianchi area appear to be some of the last remnants of primeval and old-growth forests of this species. These forests are structurally diverse and contain a rich diversity of overstory, mid-story, and understory species. Taxonomic reference: Editorial Committee of Flora Republicae Popularis Sinicae (1959–2004) for vascular plants. Abbreviations: BA = basal area; BAI = basal area increment; DBH = diameter at breast height; H = height; RBA = relative basal area.

Effects of experimental nitrogen and/or phosphorus additions on soil nematode communities in a secondary tropical forest

Vertical thermal environment of subtropical broad-leaved urban forests and the influence of canopy structure

Effects of different vegetation restoration on soil nutrients, enzyme activities, and microbial communities in degraded karst landscapes in southwest China

次生林在全球碳循环中占有重要地位,为了研究中国中亚热带次生林土壤有机碳组分特征,以四川瓦屋山中山段扁刺栲-中华木荷常绿阔叶次生林为对象,通过挖取土壤剖面分层(0-10、10-40、40-70 cm和70-100 cm)取样方式,研究土壤各有机碳组分特征。结果表明:土壤有机碳、微生物生物量碳、可浸提溶解性有机碳和易氧化碳含量均随土层深度增加而减小,0-10 cm土层有机碳含量为121.89 g/kg,高于已报道的亚热带其他常绿阔叶林和四川各类森林;0-10 cm层微生物生物量碳含量为1931.82 mg/kg,可浸提溶解性有机碳含量为697.42 mg/kg,易氧化碳含量为20.98 g/kg,高于已报道的许多相似天然林和人工林活性碳含量。土壤有机碳储量为154.87 t/hm²,在四川省各类森林中处于中等水平。研究表明瓦屋山扁刺栲-中华木荷常绿阔叶次生林活性碳含量较大,微生物活动和养分流动较为活跃,凋落物层转化为土壤碳的潜力较大,这类生态系统可能会在区域碳循环过程中扮演更为重要的角色。

<p>The Jinfo Mountain National Nature Reserve in 3A different type community (deciduous broad-leaved forest, Evergreen deciduous broad-leaved mixed forest, Evergreen broad-leaved forest) under purple ear fargesia (<em>Fargesia decurvata</em> J.L.Lu) Young are of Growth Development Research. Results display: (1) Deciduous broad-leaved forest and evergreen deciduous broad-leaved mixed forest under the purple ear fargesia shooting of early and long duration 110 d Shooting large shooting rate is high; evergreen broad-leaved forest under the shooting of late and short duration 88 D Shooting less shooting rate low; evergreen deciduous broad-leaved mixed forest in the shooting of maximum. (2) Shooting period is divided 3A stage: early stage and the end the community in purple ear fargesia into each period of time have difference evergreen deciduous broad-leaved mixed forest in the first to enter the shooting stage deciduous broad-leaved forest followed by evergreen broad-leaved forest. Shooting stage is also back are the peak back are rate of size for: evergreen deciduous broad-leaved mixed forest > Deciduous broad-leaved forest>Evergreen broad-leaved forest. (3) The same community crown layer environment under purple ear fargesia Different Period Unearthed of young are ground diameter no significant difference. In deciduous broad-leaved forest and evergreen deciduous broad-leaved mixed forest canopy environment in the Period Unearthed of young are ground diameter between no significant difference but were significantly greater than the evergreen broad-leaved forest (<em>P</em> < 0.05). (4) Purple ear fargesia young are unearthed after 80 d About complete high growth process and in line Logistic Equation was Slow-Fast-Slow Of growth trend. High growth rate for: evergreen deciduous broad-leaved mixed forest > Deciduous broad-leaved forest > Evergreen broad-leaved forest and difference significant (<em>P</em> < 0.05). (5) Purple ear understory of bamboo cloning reproduction and ramet density between have close relationship. With the ramets density of increase shooting quantity increase bamboo quantity reduce. This study show that different Community crown layer environment under purple ear bamboo growth development significant difference in evergreen deciduous broad-leaved mixed forest in development best evergreen broad-leaved forest in development worst, population density of bamboo of update development the important regulation role.</p>

PDF HTML阅读 XML下载 导出引用 引用提醒 紫耳箭竹克隆形态可塑性对典型冠层结构及光环境的响应 DOI: 10.5846/stxb201710161859 作者: 作者单位: 西南大学生命科学学院，三峡库区生态环境教育部重点实验室,西南大学生命科学学院，三峡库区生态环境教育部重点实验室,西南大学生命科学学院，三峡库区生态环境教育部重点实验室,西南大学生命科学学院，三峡库区生态环境教育部重点实验室,西南大学生命科学学院，三峡库区生态环境教育部重点实验室,西南大学生命科学学院，三峡库区生态环境教育部重点实验室,三峡库区生态环境教育部重点实验室，西南大学生命科学学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（31570612） Response of clonal morphological plasticity of Fargesia decurvata to different forest canopy structures and light conditions Author: Affiliation: Key Laboratory of Eco-Environments in Three Gorges Reservoir Region, School of Life Science, Southwest University,,,,,,Key Laboratory of Eco-Environments in Three Gorges Reservoir Region, School of Life Science, Southwest University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:在重庆金佛山国家自然保护内，选择了3种典型群落类型（落叶阔叶林、常绿落叶阔叶混交林和常绿阔叶林），使用Hemiview数字植物冠层分析系统量化群落冠层结构和光环境特征，并对林下紫耳箭竹（Fargesia decurvata）的形态可塑性特征进行调查，分析冠层结构和光环境特征改变下紫耳箭竹形态可塑性的差异，并探讨它们之间的相互关系。结果表明：（1）随着落叶阔叶林→常绿落叶阔叶混交林→常绿阔叶林演替的进行，群落的冠层开度降低，叶面积指数增加，平均叶倾角变小，趋于水平化，冠层对光的截获能力提高，林下光照的强度降低（P < 0.05）。（2）随着光照强度的降低，紫耳箭竹分株矮小化，叶片变窄，生物量积累降低，但通过增大比茎长、叶面积率和比叶面积提高对光的利用效率，并增大分枝角度和比隔长有效适应弱光环境。（3）在光照条件差的常绿阔叶林下，紫耳箭竹降低对地下茎的投资，将较多的生物量用于秆的增高增长和叶片的生长；而在光照条件好的落叶阔叶林环境下，紫耳箭竹降低对枝、叶生物量的分配，则加大对地下茎的投资，可认为是克隆植物对水分资源所表现的一种觅食行为。研究表明，紫耳箭竹种群随着冠层结构的改变发生了明显的可塑性变化，这些可塑性变化是种群对冠层结构和光环境差异的适应性反应的结果，有利于增强种群对异质生境中光资源的获取和利用；群落内部可以通过调控冠层结构的改变协调和控制小径竹种群的发展。 Abstract:Clonal morphological plasticity, closely related to the maintenance and regeneration of populations, is the ability for a plant to adapt to a changing environment. In a field experiment, the Hemiview digital canopy analysis system was used to measure the canopy structures (canopy openness, CO; leaf area index, LAI; mean leaf angle, MLA) and light conditions (direct solar radiation under canopy, Dir; diffuse solar radiation under canopy, Dif; Total solar radiation under canopy, Tot) in three typical forest types (deciduous broad-leaved forest, evergreen and deciduous broad-leaved mixed forest, evergreen broad-leaved forest) in Jinfo Mountains National Nature Reserve, Chongqing. The clonal morphological plasticity of understory dwarf bamboo, Fargesia decurvata, was also measured. Moreover, the relationship between canopy structure and morphological plasticity of F. decurvata was discussed. The results showed that:(1) With the development of forest succession, the CO and MLA decreased, but LAI increased, resulting in the increase in light interception capability of forest canopy and the decrease in the light intensity under forest canopy (P < 0.05). (2) Forest canopy condition had a significant effect on the morphological plasticity of F. decurvata ramets. With the decrease in light intensity, the culm height, basal diameter, leaf area, and biomass of F. decurvata ramets decreased. However, decreased light intensity can increase the specific culm length, leaf area ratio, and specific leaf area to improve the utilization efficiency of light and increase the branch angle of spacer and specific spacer length to adapt to low light environments. (3) Under the low light environment in an evergreen broad-leaved forest, F. decurvata reduced its investment in rhizome but allocated more biomass for culm and leaf growth. However, in the deciduous broad-leaved forest, F. decurvata reduced the allocation of branches and leaves and increased the investment in rhizome growth (spacer length and diameter), which can be considered as a foraging behavior to searching much more water resources. These results suggested that the morphological plasticity of F. decurvata underwent significant change in different forest canopies, which is the result of adaptive response to different forest canopy structures and light conditions and enhances the ability to acquire and utilize light resources in heterogeneous light environments. Moreover, the communities may be able to coordinate and control the development of dwarf bamboo by controlling the change of canopy structures and light conditions. 参考文献 相似文献 引证文献

Soil respiration is an important pathway of carbon release from the terrestrial biosphere to the atmosphere, which plays a key role in ecosystem carbon cycling. However, the response and mechanism of soil respiration to nitrogen and phosphorus addition in legume plants are still unclear. Here, a pot experiment planted with soybean (Glycine max (L.) Merr.) was conducted to investigate the effects of nitrogen (N) and phosphorus (P) addition on soil respiration. Four treatments were designed: control, N addition, P addition, and both N and P addition. Soil respiration was measured twice a month from June to September in 2022. Our results showed that nutrient addition treatments presented significantly negative effects on soil respiration. In particular, nitrogen addition not only directly affected soil respiration, but also indirectly impacted soil respiration by altering soil nitrate nitrogen content. Elevated soil nitrate nitrogen content could inhibit soybean root nodule number and reduce biomass allocation to roots, thereby decreasing soil respiration. Furthermore, phosphorus addition and nitrogen–phosphorus co-addition strongly inhibited soybean nodulation by changing soil pH value, thus inhibiting soil respiration of soybean. The findings provide baseline information for optimizing nutrient management in legume crops.

Soil microbial carbon use efficiency (CUE) reflects the proportion of absorbed carbon allocated to biomass synthesis by microorganisms. Investigating changes in soil microbial CUE under nitrogen addition would contribute to a deeper understanding of soil carbon sequestration potential in forest ecosystems. To investigate the responses of soil chemical properties, microbial biomass, and extracellular enzyme activity to nitrogen addition, we conducted a nitrogen addition experiment with six levels (0 (CK), 50 (N50), 100 (N100), 150 (N150), 200 (N200), 250 kg·hm-2·a-1(N250)) in subalpine evergreen broad-leaved forest and Quercus aquifolioides forest in central Yunnan. Microbial CUE was calculated using a biogeochemical model. Then, we examined the responses of soil microbial CUE to nitrogen addition. The results showed under nitrogen addition, soil microbial CUE in evergreen broad-leaved forest exceeded that in Q. aquifolioides forest. Both forest types showed higher microbial CUE in the 0-10 cm soil layer than in the 10-20 cm layer. In evergreen broad-leaved forest, soil microbial CUE first increased then decreased with rising nitrogen addition levels decreasing by 2.9%-41.3% compared to the control. In contrast, Q. aquifolioides forest exhibited a pattern with a positive impact of high nitrogen levels but a negative effect of low nitrogen levels. Under N200 and N250 treatments, CUE significantly increased by 8.1% and 11.6%, while it decreased under other nitrogen addition treatments. The primary factors influencing soil microbial CUE in evergreen broad-leaved forest were bacterial and fungal community α-diversity and soil pH, whereas the factors were bacterial and fungal community α-diversity, soil NO3--N, and pH in Q. aquifolioides forest. The dominant groups differed between the two forest types, and the changes in community structure significantly influenced soil microbial CUE. Forest type, nitrogen addition, and soil depth jointly determined the variations in CUE for both evergreen broadleaf and Q. aquifolioides forest, indicating that the response of ecosystem carbon storage potential to nitrogen deposition exhibited significant ecological specificity.

We analyze 35 Eocene and Neogene floras from Europe (fruits, leaves, and pollen of woody taxa) to trace fruit dispersal syndromes in the fossil record. These derive from vegetation units spanning paratropical broad-leaved evergreen, mixed mesophytic, broad-leaved evergreen, and broad-leaved deciduous forests. The dispersal syndromes distinguished are fleshy and nonfleshy zoochorous, anemochorous, autochorous, and hydrochorous. Additionally, zonal and azonal taxa were distinguished to test whether the dispersal syndromes are equally distributed reflected in the zonal and azonal record. The results show very similar proportions of dispersal modes in the fossil record compared to modern forests. This suggests a consistent relationship in the Northern Hemisphere between vegetation type and dispersal spectrum in the last 50 million years. Paratropical forests show the highest values of fleshy zoochorous taxa and the lowest of anemochorous taxa. Fleshy zoochorous proportions remain high in broad-leaved evergreen forests. They are lower in subhumid sclerophyllous and lowest in broad-leaved deciduous forests. For anemochorous taxa this trend is inverted: lowest values derive from paratropical forests and highest from subhumid sclerophyllous and broad-leaved deciduous forests. Nonfleshy zoochorous taxa always show relatively low percentages but their values are somewhat higher in subhumid sclerophyllous and broad-leaved deciduous forests than in broad-leaved evergreen forests. Autochorous and hydrochorous dispersal modes are always very low. Whether in the Eocene or Neogene, the azonal record always has a higher anemochorous fraction. Because climate change instigates vegetational change, our findings link climate to changing resources for smaller vertebrates, although the consistent availability of nonfleshy zoochorous fruits since the late Eocene suggests a consistent resource, especially for rodents.

The phenomenon of nitrogen deposition resulting in species loss in terrestrial ecosystems has been demonstrated in several experiments. Nitrogen (N) and phosphorus (P), as major nutrients required for plant growth, exhibit ecological stoichiometric coupling in many ecosystems. The increased availability of nitrogen can exacerbate the ecological effects of phosphorus. To reveal the ecological effects of phosphorus under nitrogen-limiting and non-limiting conditions, we conducted a controlled N-P interaction experiment over 5 years in the Hulunbuir meadow steppe, where two nitrogen addition levels were implemented: 0g N·m-2·a-1 (nitrogen-limiting condition) and 10g N·m-2·a-1 (nitrogen-non-limiting condition), together with six levels of phosphorus addition (0, 2, 4, 6, 8, and 10g P·m-2·a-1). The results showed that nitrogen addition (under nitrogen-non-limiting conditions) significantly decreased species diversity in the steppe community, which was exacerbated under phosphorus addition. Under nitrogen-limiting conditions, phosphorus addition had no marked impact on species diversity compared to the control; however, there were substantial differences between different levels of phosphorus addition, exhibiting a unimodal change. Under both experimental nitrogen conditions, the addition of 6g P·m-2·a-1 was the threshold for affecting the community species diversity. Nitrogen addition reduced the relative biomass of legumes, bunch grasses, and forbs, but substantially increased the relative biomass of rhizomatous grasses. In contrast, phosphorus addition only markedly affected the relative biomass of forbs and rhizomatous grasses, with the former showing a unimodal pattern of first increasing and then decreasing with increasing phosphorus addition level, and the latter exhibiting the opposite pattern. The different responses of rhizomatous grasses and other functional groups to nitrogen and phosphorus addition were observed to have a regulatory effect on the changes in grassland community structure. Phosphorus addition may increase the risk of nitrogen deposition-induced species loss. Both nitrogen and phosphorus addition lead to soil acidification and an increase in the dominance of the already-dominant species, and the consequent species loss in the forb functional group represents the main mechanism for the reduction in community species diversity.

Understanding the relationship between tree species diversity and above-ground carbon (AGC) storage in tropical forests is essential for a sustainable flow of ecosystem goods and services. Although tropical forests of Vietnam are of particular interest due to their high biodiversity and carbon density, few studies have evaluated the relative importance of species composition, tree species diversity and forest structure on AGC storage by forest vegetation type. In this study, we tested for the influence of taxonomic diversity, forest structure and species composition on AGC storage in evergreen broad-leaved and deciduous forests of Southeast Vietnam. Data was collected within 137 rectangular plots (25 m × 20 m), randomly selected across a deciduous forest (DF) and four evergreen broad-leaved forest (EB) categories, with different stand­ing volumes levels: very poor (EBG), poor (EBP), medium (EBM) and rich (EBR). In total, we identified 3687 individuals from 110 tree species belonging to 46 families in 6.85 hectares of sampled area. AGC stor­age significantly differed among forest categories, ranging from 14.81 Mg ha−1 in EBG to 146.74 Mg ha−1 in EBR. There was higher AGC in the medium diameter class (20-40 cm), except for EBR where there was higher AGC within individuals of 40-60 cm in diameter. Taxonomic diversity was weakly correlated with AGC while stand structure (stem density and maximum diameter) were strongly correlated. Our results suggest that maintaining the abundance distributions of remnant tree species, particularly that of large trees, is one important method to enhance AGC storage in the tropical ecosytems of southern Vietnam.

The effects of nitrogen addition on fungal diseases in agroecosystems have been widely documented, while largely unknown is how phosphorus fertilization will affect foliar fungal diseases in natural ecosystems. Here, we implemented a factorial experiment with nitrogen and phosphorus addition in an alpine meadow of the Qinghai‐Tibetan Plateau to test the effects of nutrition fertilization on foliar fungal diseases severity (i.e., % of the leaf area that was covered by fungal lesions) at plant species‐, family‐ and community‐levels, respectively, and also among different disease types (biotroph vs. necrotroph). At plant species‐level, nitrogen and phosphorus addition increased diseases severity for two and five plant species respectively. At plant family‐level, nitrogen addition increased pathogen load on Poaceae plants, while phosphorus fertilization increased pathogen load on Scrophulariaceae. Moreover, we found that addition of both nitrogen (p = .034; coefficient = 0.436) and phosphorus (p = .012; coefficient = 0.622) increased pathogen load of biotrophic pathogens, but only nitrogen addition (p = .010; coefficient = 1.769) increased pathogen load induced by necrotrophic pathogens. At plant community‐level, nitrogen addition (p = .009; coefficient = 0.218) alone, rather than phosphorus addition or the interaction of nitrogen and phosphorus addition, increased community pathogen load. We concluded that nitrogen addition affects foliar fungal diseases more than phosphorus at the community‐level, and fungal diseases caused by necrotrophic pathogens were more sensitive to nitrogen addition.

Background The decline in soil organic carbon accumulation caused by intensified nitrogen deposition is concerning. Although phosphorus input may alleviate the negative impacts, there is still a research gap regarding the mechanisms, particularly those involving the soil biota, that drive the stability of soil organic carbon. Methods We conducted a 2-year nitrogen (0, 30 and 90 kg N ha – 1 yr – 1 ) and phosphorus (0, 30 kg P ha – 1 yr – 1 ) addition experiment with six treatments in a 25-year-old Pinus massoniana plantation in subtropical China. Results The addition of external nutrients improved soil nutrient availability but led to a decrease in pH. Low nitrogen input promoted the particulate organic carbon (POC) and total organic carbon, whereas high nitrogen input had the opposite effect. Phosphorus addition alleviated these negative impacts to some extent. Nitrogen and phosphorus addition significantly affected the dissimilarity of soil biological communities. Nitrogen treatments generally reduced the alpha diversity index of soil bacteria, while the trend for fungi was the opposite. Arthropods showed a rise followed by a decline, with phosphorus addition weakening these effects. Soil respiration decreased with increasing nitrogen addition, and phosphorus addition didn’t alter this trend. The POC was primarily influenced by the soil environment-microorganism-respiration and environment-microorganism pathways, whereas the mineral-associated organic carbon (MAOC) was mainly influenced by the soil environment-arthropod pathway. POC (Path coefficient, pc = 0.524) and MAOC (pc = 0.237) directly determine the accumulation of organic carbon. This conceptual model explained 59.4% of the variation in total organic carbon (Goodness-of-fit, GOF = 0.594), thereby delineating the integrated mechanisms underlying SOC accumulation. Conclusions Excessive nitrogen input was unfavorable for organic carbon accumulation, while phosphorus addition partially mitigated the negative effects of nitrogen excess. Under this context, active organic carbon was significantly influenced by soil microorganisms and soil respiration, whereas stable organic carbon was primarily affected by soil arthropods. Graphical Abstract