Significant Differences In Total Nitrogen Research Articles

Effects of Stand Density on Tree Growth, Diversity of Understory Vegetation, and Soil Properties in a Pinus koraiensis Plantation

The regulation of stand density has been studied in specific aspects of plantations with different age categories. A clearer understanding is still required of the extent to which stand density impacts multiple plantation attributes such as tree growth, understory vegetation diversity, and soil properties in Korean pine (Pinus koraeinsis Sieb. et Zucc) plantations. This study utilized a 43-year-old middle-aged Korean pine plantation in Qingping Forest Farm in northeast China to answer the research question posed. Three stand density levels, low stand density (LSD, 716 trees/ha), medium stand density (MSD, 850 trees/ha), and high stand density (HSD, 916 trees/ha) were studied for their effects on plantation attributes enumerated above. The results revealed a significant (p < 0.05) effect of stand density on mean stand volume (m3). Medium stand density had the highest mean stand volume of 26.16 (±0.27) m3 while the lowest stand volume was recorded for the low stand density at 14.90 (±1.72) m3. Also, significant differences in total nitrogen, total potassium, available nitrogen, available potassium, and percentage soil moisture content were observed among stand density levels. Additionally, stand density was found to have significant effects on species richness, Shannon–Wiener, and Simpson’s diversity indexes for the shrub and herb layers of the plantation. This study shows that a medium stand density is the most optimal for promoting tree growth and understory biodiversity, as well as enhancing the status of certain soil nutrients. Thus, medium density achieves a balance between growth, nutrient availability, and biodiversity in middle-aged Korean pine plantations after a short period of thinning. These findings provide valuable knowledge for forest management, emphasizing the significance of continuous, long-term, and site-specific research.

Stocks and Sources of Soil Carbon and Nitrogen in Non-Native Kandelia obovata Afforestation and Spartina alterniflora Invasion: A Case Study on Northern Margin Mangroves in the Subtropical Coastal Wetlands of China

For decades in China, carbon neutrality policies have spurred the establishment of northern margin mangroves as artificial blue carbon ecosystems. However, there has been limited research on the impact of plantation and invasion on the stocks and sources of soil carbon and nitrogen in rehabilitated coastal wetlands. Non-native Kandelia obovata afforestation began on Ximen Island, Zhejiang, China, where Spartina alterniflora invasion had also occurred decades ago. Soil cores were collected from both mangrove and salt marsh habitats with depths from 0 to 50 cm and were analyzed for total carbon (TC), soil organic carbon (SOC), total nitrogen (TN), and the isotope of carbon and nitrogen in sediments. The results indicated that there were no significant differences in the TC, SOC, and C/N ratio between the K. obovata and the S. alterniflora, but there were significant differences in TN, isotope δ13C, and δ15N. The SOC content of both ecosystems in the 0–20 cm layer was significantly higher than that in the 30–50 cm layer. Our study has shown that the main sources of carbon and nitrogen for mangroves and salt marshes are different, especially under the impact of external factors, such as tidal waves and aquaculture. These findings provide insight into the ecological functioning of subtropical coastal wetlands and an understanding of the biogeochemical cycles of northern margin mangrove ecosystems.

松花江哈尔滨段浮游植物群落格局及其与环境因子的相关性

PDF HTML阅读 XML下载 导出引用 引用提醒 松花江哈尔滨段浮游植物群落格局及其与环境因子的相关性 DOI: 10.5846/stxb201909262022 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金资助项目（31870187）；哈尔滨师范大学博士启动金项目（XKB201912） Correlation between phytoplankton community patterns and environmental factors in Harbin section of the Songhua River Author: Affiliation: 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:松花江是黑龙江在我国境内的最大支流，流经吉林、黑龙江两省。松花江哈尔滨段是哈尔滨市工农业生产与生活用水的重要水资源，近年来由于人类活动的频繁影响，水体质量有所下降。鉴于此，于2018年春、夏、秋三季（4月、8月和10月），在松花江哈尔滨段设置14个采样点，对电导率、总氮和总磷等理化指标进行测定，同时对其浮游植物群落结构及环境因子相关性进行研究。利用群落相似性分析（ANOSIM）探讨浮游植物群落时空分布差异；通过SIMPER分析筛选出影响群落时空格局的关键物种。基于优势种和10项理化指标的冗余分析（RDA）揭示了浮游植物群落生态分布特征并对关键影响因子进行识别。研究结果表明，调查期间共鉴定浮游植物136种，其中优势种15种，群落结构主要以硅藻门和绿藻门的物种构成。松花江哈尔滨段浮游植物群落结构与过去10余年间相比较为稳定。ANOSIM和SIMPER分析表明，季节变化和人为活动干扰对浮游植物群落时空格局具有一定驱动作用，蓝藻门物种的空间分布活动干扰影响明显。RDA分析表明，浮游植物分布特征与水环境时空异质性关系密切，驱动松花江哈尔滨段浮游植物群落时空分布的主要水环境因子为电导率、总磷、浊度和pH。 Abstract:The Songhua River, the largest tributary of the Heilongjiang River, flows through Jilin and Heilongjiang province. The Harbin section of the Songhua River starts from the upstream of Zhu Shuntun and ends at the Dadingzi Mountain in the lower reaches. It is an important water resource for industrial, agricultural and domestic use in Harbin city. Recent years, the intensively anthropogenic activities have resulted in water pollution. The water quality and biodiversity of Harbin section of the Songhua river has been attracted wide attention. At present, more and more studies focused on phytoplankton diversity and community structure. However, the study on phytoplankton in Harbin section of the Songhua River is still in its infancy. To explore the phytoplankton community structure and its relationship with environmental factors in Harbin section of the Songhua River, multivariate statistical analysis was conducted in this study. All sampling sites of Harbin section of the Songhua River were divided into two parts, sampling sites under intense human disturbance and other less polluted sites. A total of 14 sampling sites, the phytoplankton community and 10 environmental parameters were investigated in the spring (April), summer (July), and autumn (October) of 2018. The spatial and temporal distribution differences of phytoplankton community were analyzed by analysis of similarity (ANOSIM). The key species with contribution to the spatio-temporal patterns were identified by similarity percentage (SIMPER) analysis. Additionally, the redundancy analysis (RDA) based on dominant species and 10 environmental variables revealed the ecological distribution of phytoplankton community and identified main factors. The results showed that a total of 136 species of phytoplankton were detected, including 15 dominant species. The species composition was dominated by Bacillariophyta and Chlorophyta (76%), followed by Cyanobacteria (12%), Cryptophyta (7%) and others. Compared with the past 10 years, the community structure belonging to Bacillariophyta-Chlorophyta was relatively stable. Among the three seasons, except for the physical and chemical indicators of specific conductivity (SpCond.), oxidation-reduction potential (ORP) and total phosphate (TP), others were significant differences (P<0.05). During the study, the abundance of phytoplankton in Harbin section of the Songhua River was 7.92×106-21.76×106 ind./L, and the average was 15.27×106 ind./L. The independent sample t-test showed that there were significant differences in total nitrogen (TN), chemical oxygen demand (CODMn) and chemical oxygen demand (BOD5) among the sampling sites affected by human disturbance and other sites (P<0.01). Additionally, there was significant difference of SpCond. at the 0.01 level in different sites, while other physical indicators such as pH did not change greatly (P>0.05). ANOSIM and SIMPER analysis showed that seasonal changes and human-induced disturbances in Site 4 to Site 7 had effects on the spatial and temporal patterns of phytoplankton community. The spatial distribution of Cyanobacteria species was significantly affected by human activity. The results of RDA analysis found that the distribution characteristics of phytoplankton were closely related to the spatio-temporal heterogeneity of water environment. SpCond., TP, turbidity (Tur.) and pH were the key driving factors of phytoplankton community in Harbin section of the Songhua River. 参考文献 相似文献 引证文献

The Impact of Wastewater Discharge and Agriculture on Water Quality and Nutrient Retention of Namatala Wetland, Eastern Uganda

The Namatala Wetland in Uganda faces severe degradation from agricultural development and urbanization. Besides the Namatala River and tributary rural streams, the wetland receives surface water from Mbale town and wastewater from two sets of wastewater stabilization ponds. The objective of this study was to examine water quality, and sediment and nutrient retention in different land use zones. Five hydrogeomorphic units (HGMUs) were distinguished on the basis of soil, hydrology and land use. HGMUs 1 and 2 in the upstream part of the wetland are characterized by drainage channels and mixed agriculture. HGMU 3 is a wet floodplain with intensive rice farming. HGMU 4 and 5 are permanently wet units in the downstream part of the wetland with moderate rice farming and partly intact papyrus (Cyperus papyrus L.) vegetation. Stream discharge was measured, and surface water samples collected, monthly from the river channel, the tributaries, and the five HGMUs from April 2015 to October 2016. Significant differences in total nitrogen (TN), phosphorus (TP) and total suspended solids (TSS) were observed among the streams and among the five HGMUs, with highest concentrations in urban streams and lowest in the main river channel and rural streams. Among the HGMUs, nutrients and TSS were highest within HGMU 3 and lowest in HGMU 1 and 5. Loads of nutrients and sediment into the wetland were greater from the main river channel compared with urban and rural streams. Regressions of net TN, TP and TSS yields for each HGMU against river discharge showed a net loss of nutrients and sediments in HGMU 3 with the most intensive agriculture, and net retention in HGMUs 4 and 5 which mostly maintain their wetland character. This study shows that sediment and nutrient retention in the downstream part of the wetland compensate for increased export caused by agricultural and urban land use in the middle and upper zones of the wetland, thus maintaining net nutrient retention of Namatala Wetland. However, there is a trade-off between economic development and wetland protection and future management planning should incorporate more sustainable farming practices and improved wastewater treatment.

Evaluation and Classification of Soil Fertility Potentials of Gombi Area of Adamawa State, North- eastern Nigeria

A study was conducted to evaluate the soil fertility potential of Gombi area of Adamawa State, Nigeria. A total of eighty (80) soil samples composite from 0-20 and 20-50cm depths were collected from selected representative locations from the ten (10) wards of the study area and analyzed using standard laboratory pro- cedures. Results obtained revealed that the texture of the soil ranged from sandy loam to sandy clay across the study area. Soil pH was slightly acidic ranged from 6.49 to 6.92. Similarly, there no significant differences in total nitrogen and or- ganic carbon contents among both locations and sampling depths. However, total nitrogen and organic carbon contents were generally low and ranged from 6.7 to 10.3 g kg-1 for organic carbon and 0.88 to 1.0 g kg-1 for total nitrogen across the locations. Similarly, available phosphorus contents were generally low and were linked to P fixation by Fe and Aluminium under the acidic pH range. Three soil FCC classes were identified; SLdek, Ldek, and LSdek with SLdek dominating in six out of ten areas. Sandy nature of the soils, low nutrient reserve, and cation exchange reactions are the dominant constraints in the soils of the area. Integrat- ed soil fertility management which recognizes the use of local inputs such as or- ganic materials available within the environment and appropriate synthetic ferti- lizer practices could be employed to improve the soil constraints to maintain and sustain the productivity of the soils.

Research on the soil nutrient characteristics of tea plantation

This paper based on the sampling and analyzed the soil nutrient status in the tea plantation of Qishan Mountain, western Chongqing. The results show that soil pH value of the tea plantation was found to be acidic, and the available Phosphorus, available Manganese, available Zinc, available Copper and available Iron were abundant. While Organic matter, total Nitrogen, available Potassium, and effective Magnesium content were relatively lacking. There were significant differences in total Nitrogen, Organic matter, available Phosphorus, available Zinc, and available Iron between different tea planting years. Fertilization should be based on the soil nutrient status in the management of tea gardens, in order to increase the income of the plantation.

Effects of vegetation, terrain and soil layer depth on eight soil chemical properties and soil fertility based on hybrid methods at urban forest scale in a typical loess hilly region of China.

Although the spatial mapping and fertility assessment of soil chemical properties (SCPs) are well studied in the Loess Plateau region of China at farmland scale, little is known about spatial mapping the SCPs and their fertility and their influence factors at urban forest scale. The objectives of this study were to (1) compare the performance of two spatial interpolation methods, Ordinary kriging (OK) and regression kriging (RK), and (2) explain the relationships of the vegetation, terrain, and soil layer depth between the eight SCPs and their fertility, and (3) find the limiting factors of soil comprehensive fertility in this study area? The Yan’an urban forest was taken as study case, used hybrid spatial interpolation methods based on OK and RK to mapping eight SCPs and the soil fertility in each soil layer (0–20 cm, 20–40 cm, and 40–60 cm) for 285 soil samples. The results indicated that RK outperformed OK for total nitrogen (TN), available potassium (AK), organic matter (OM) in 0–60 cm profile and available phosphorus (AP) in the 0–20 cm and 40–60 cm soil layers because RK considered the impact of terrain. The terrain factors, comprising the relative terrain position, slope, aspect, and relative elevation significantly affected the SCPs and spatial heterogeneity of fertility, where the vegetation cover types determined the average SCPs to some extent. On average, the six SCPs (except total potassium and AP) and the fertility decreased as the soil layer depth increased. Ten vegetation cover types comprising broadleaved mixed natural forest (BM), cultivated land (CL), economic forest (EF), grassland (GL), Platycladus orientalis natural forest (PON), Platycladus orientalis plantation (POP), Pinus tabuliformis plantation (PT), Quercus wutaishanica natural forest (QW), Robinia pseudoacacia plantation (RP), and Shrubwood (SW) were associated with significant differences in TN, OM, AN, AP, and AK, across the three soil layers. QW, PON, and BM also had higher content of TN, OM, AN, and AK contents than the other vegetation cover types. There were small differences in TK, AK, and pH among the 10 vegetation cover types. We concluded that AN, TN, and OM are the limiting factors of soil comprehensive fertility in this region. These results improve understanding of the spatial mapping, influence and limiting factors of SCPs and their fertility at urban forest scales.

Effects of extensive bottom cultivation of tropical oyster Crassostrea belcheri on benthic invertebrate community structure in Ban Don Bay, Suratthani Province, Southern Thailand

The diversity, distribution, and species richness of benthic invertebrates were examined under extensive bottom cultivation of the tropical oyster Crassostrea belcheri during the summer of 2015 at Ban Don Bay, Suratthani Province, Southern Thailand. Oyster farms that had been operating for 25 years were selected for the study, and four sampling sites were allocated along each transect as (i) at the center of the farm, (ii) inside the farm, (iii) at the farm boundary, and (iv) a reference site. Results indicated that a total of 23 families and 28 species of benthic invertebrate taxa were recorded from the four sampling sites, and the macrobenthic invertebrates inhabiting all study sites consisted mainly of gastropods (11 species), polychaetes (11 species), and bivalves (8 species). No significant differences in total density, diversity index, evenness index, and species richness index of benthic invertebrates were found among each sampling site (P > 0.05). Significant differences in total nitrogen, nitrate, nitrite, total ammonia, sulfide, total phosphorus, organic matter, and grain sizes of sediment were found among each sampling site, but no significant differences in pH and total nitrogen were found. Among the independent variables analyzed, correlation analysis showed relationships between benthic diversity indices and abiotic variables. There were no clear patterns of differences in the detrimental environmental effects between sampling site locations, which indicated a minimal ecological impact of oyster cultivation.

Swine Anaerobic Lagoon Nutrient Concentration Variation with Season, Lagoon Level, and Rainfall

Twenty swine anaerobic lagoons (8 finish, 6 nursery, and 6 sow) were monitored for lagoon liquid nutrient concentrations and liquid level above or below the stop-pump level. Weekly rainfall was also recorded. Significant differences in total nitrogen (N) concentrations existed between lagoons and also between types of farms. The N concentration varied within the same lagoon by a factor of two or more during the 4-yr study period and typically displayed a seasonal trend of decreasing during the summer and increasing during the winter. Years of operation (8 to 29 yr) were not a significant factor for mean N concentration over the 4-yr period. The lagoon liquid level was not a significant factor for N or total phosphorus (P) concentration. The finish farms displayed a decreasing trend of average annual nitrogen concentration with increase in annual rainfall.

The Environmental Effect of a Land-Based Trout Farm on Yuvarlakçay, Turkey

The objective of this study was to assess the environmental impact of one of the biggest flow-through rainbow trout farms located in South-Western Turkey between February and December 2006. The feeding water is obtained from the Yuvarlakcay Stream (Muðla, Turkey) at a mean flow rate of 2.86 Litre s-1 per ton of the annual fish production (700 t year-1) with drum filtration used for the effluent treatment of the farm. Bi-monthly sampling was conducted from the inlet and discharge water (before and after treatment) at the same hour of each sampling day. No significant differences in total nitrogen (TN), total phosphorus (TP), biochemical oxygen demand (BOD5), and chemical oxygen demand (COD) were found in the effluent, although these parameters were found to have increased in the discharged water. The dissolved oxygen (DO) and pH of the effluent water were found to be significantly affected by the fish farming activities. The effluent treatment efficiencies were found to be 7.77% for TP, 8.67% for TN, 16.58% for BOD5, and 13.16% for COD, respectively. The annual TP load of the trout farm after effluent treatment was found to be 5.68 kg P per ton of fish produced, and 5.30 kg P per ton of feed used, respectively. The average TP load without any effluent treatment determined via chemical and biological methods was 7.66 and 10.46 kg P per ton of fish produced, respectively.

Interaction of root-knot nematode and mycorrhizal fungi on common beanPhaseolus vulgaris L.

The interactions of root-knot nematode and VAM fungus on common bean plants (Phaseolus vulgaris L.), and the sequence of nematode infection were studied in the greenhouse. The inoculation with VAM fungus caused a significant increase in plant height and fresh weight compared with non treated plants.Meloidogyne infection unsignificantly decreased plant height and dry weight. When fungus was inoculated at 15 and 30 days prior toM. incognita infection, a significant increase in fresh weight was observed. There were no significant differences in total nitrogen (mg/plant) between plants inoculated withM. incognita alone or those inoculated with bothM. incognita and VAM fungus at the same time or 15 days after the fungus inoculation. Plants preinoculated with VAM fungus 30 days prior to nematode infection had a significant increase in total nitrogen. The inoculation with VAM fungus caused a significant increase in phosphorus content. However, it was significantly decreased in plants inoculated with nematode alone and in plants inoculated with VAM fungus andM. incognita at the same time. Gall index and final nematode population were significantly increased when nematodes were treated at the same time with fungus, although there were significant decrease in nematode final population and gall index when the plants were treated with nematodes at 15 and 30 days after mycorrhizal infection. A decrease in percentage of fungal colonization was observed when nematodes were inoculated with fungus at the same time.

Effects of mound-cultivation (bedding) on concentration and conservation of nutrients in a sandy podzol

This study aimed at assessing the conservation of soil nutrients following mound-cultivation (bedding) of a sandy podzol by Rome plough prior to establishment of a second-rotation plantation of Pinus radiata. Organic matter, and hence total nitrogen, available phosphorus, and exchangeable cations, was concentrated in the centre of the mound (the planting line). The C/N ratio throughout the profile of both mounded and control plots was 20, and CEC increased by 1 cmol(NH 4 +)kg −1 of organic matter. There were no significant differences in total nitrogen, available phosphorus (Bray and Kurtz No. 2), CEC (NH 40Ac, pH 7), and exchangeable cations in the surface 40 cm of soil between mounded and control plots measured 9 years after cultivation and mounding. That there was no depletion of nutrients, together with associated findings that Rome ploughing resulted in a significant increase in wood volume and significant decrease in growing cost, has important implications for management of second-rotation pine plantations on Australian soils of marginal fertility.

A comparison of the organic matter, biomass, adenosine triphosphate and mineralizable nitrogen contents of ploughed and direct-drilled soils

SUMMARYSoil samples were taken from four field experiments on the growth of cereals in direct-drilled and in mouldboard-ploughed soil. When sampled, one of the experiments had run for 5 years, one for 6, one for 8 and one for 10 years. Sampling was to just below plough depth and was done on an ‘equivalent depth’ basis, i.e. the more compact direct-drilled plots were sampled more shallowly than the ploughed plots in such a way that both samples represented the same weight of soil per unit area. No significant differences in total nitrogen or in total organic carbon were observed between cultivation treatments at any of the four sites.In three of the four sites, there was no significant difference in microbial biomass carbon, adenosine 5'-triphosphate (ATP), or mineralizable nitrogen between directdrilled and ploughed soils. In the fourth, which contained more clay than the others, there was slightly more biomass carbon and ATP in the direct-drilled soil. As microbial biomass carbon (or ATP, which is closely correlated with microbial biomass carbon) responds more rapidly to changes in management than do total carbon and nitrogen, a change in biomass carbon should provide early warning of changes in soil organic matter, long before changes in total carbon and nitrogen become measurable. That no such change was observed, with one partial exception, is evidence that a change from traditional methods of cultivation to direct drilling has little effect on soil organic matter other than altering its distribution in the soil profile.

Hybrid Vigor in a Tomato Cross

1. Growth and development of two inbred lines of tomato and their hybrid were followed with respect to increase in weight, increase in height, differences of branching pattern, total phosphorus content, total nitrogen content, total starch content, catalase activity of the stem tips, and total proteolytic activity of germinating seeds and seedlings. 2. The morphological data indicate an early established and subsequently maintained size advantage for the hybrid. 3. No significant differences in total nitrogen, total phosphorus, or starch content were recorded. 4. The hybrids appeared to have higher catalase activity in stem tips, and there definitely were differences in the pattern of development of total proteolytic activity. 5. The results suggest that in certain instances the investigation of the bases of heterosis should be confined to the early growth stages and should deal with differences in the development of the enzyme systems and their activity.