Variation In Soil Enzyme Activities Research Articles

Effects of experimental warming on soil enzyme activities in an alpine swamp meadow on the Qinghai-Tibetan Plateau

Information about the response of soil enzymes to field warming in permafrost regions is scarce, and the potential mechanisms by which warming combined with biotic and abiotic factors affect soil enzyme activities in alpine grasslands remain unclear. A 3-year in situ experiment with two warming levels (2.7 °C and 5.3 °C) was conducted in an alpine swamp meadow to investigate the effects of experimental warming on 5 soil enzyme activities involved in soil carbon and nitrogen cycling, and the relationships between soil enzyme activities and soil variables related to physicochemical properties and nutrient levels were examined. Results showed that warming had obvious positive effects on soil moisture (SM), soil organic carbon, total nitrogen, and NH4+-N contents, especially in the surface soil layer. Soil NO3--N tended to decrease under moderate warming, while it significantly increased under high warming. Meanwhile, during the entire growing season, warming strongly enhanced invertase and amylase activities by 39.2–49.0% and 109.9–191.0%, respectively. In contrast, urease activities were significantly decreased by 36.8–55.7% in warming plots and there were no significant differences in catalase or cellulase activities among treatments during the whole growing season, while catalase activities in warming plots were significantly decreased by 2.6–4.0% in June. These inconsistent responses of soil enzyme activities to experimental warming could be partially explained by warming-induced changes in soil variables. Redundancy analysis showed that soil NO3--N and SM were the most important factors, which explained 29.8% and 19.7% of the variations in soil enzyme activities, respectively, suggesting that the warming-induced increase in SM could weaken the soil aeration status and enhance enzyme and substrate diffusion, strongly affecting soil nitrification and microbial enzyme production.

Long‐term rice cultivation improved coastal saline soil properties and multifunctionality of subsoil layers

AbstractRice cultivation has been found to be an effective and feasible approach for improving saline soils and increasing food production. Most studies on the improvement of rice cultivation on saline soil have focused on the several individual soil properties in the topsoil, and we know little about the importance of rice cultivation for improving multifunctionality in coastal saline soils. We investigated basic soil properties (soil physical sand content, soil physical clay content, pH, EC, soil organic carbon, total nitrogen, alkaline hydrolysis nitrogen, available potassium, available phosphorus), enzyme activities (urease, catalase, protease) and soil multifunctionality (SMF) in 0–20 cm, 20–40 cm, 40–60 cm, 60–80 cm and 80–100 cm soil layers with rice cultivated for 0 (tidal flat; CK), 20 (R20), 44 (R44) and 70 years (R70). We found that soil EC was alleviated markedly in the first 20 years after rice cultivation. Soil physical sand content, pH, EC and available potassium (AK) decreased while total nitrogen (TN), alkaline hydrolysis nitrogen (AN), urease (URE), catalase (CAT) activities and SMF increased with the increase in rice cultivation years. The highest soil total organic carbon (SOC) was shown in R44. Soil pH, EC, AK and physical sand content increased while SOC, TN, AN, enzyme activities decreased with the increase in soil depth. Redundancy (RDA) analysis showed soil physicochemical properties explained 97.53% of the variation in soil enzyme activities. Soil CAT, URE and protease (PRO) had a positive correlation with soil physical clay content, SOC, TN, AN and AP while negatively correlated with pH and AK. The increased SOC and clay content by rice cultivation might be the main reasons stimulating soil enzyme activities. In summary, long‐term rice cultivation could alleviate soil salinity, increased SMF down to 1 m, implying that rice cultivation effectively improved coastal saline soil, and the improvement could last for 70 years.

Fungal Communities Are More Sensitive to the Simulated Environmental Changes than Bacterial Communities in a Subtropical Forest: the Single and Interactive Effects of Nitrogen Addition and Precipitation Seasonality Change.

Increased nitrogen deposition (N factor) and changes in precipitation patterns (W factor) can greatly impact soil microbial communities in tropical/subtropical forests. Although knowledge about the effects of a single factor on soil microbial communities is growing rapidly, little is understood about the interactive effects of these two environmental change factors. In this study, we investigated the responses of soil bacterial and fungal communities to the short-term simulated environmental changes (nitrogen addition, precipitation seasonality change, and their combination) in a subtropical forest in South China. The interaction between N and W factors was detected significant for affecting some soil physicochemical properties (such as pH, soil water, and NO3- contents). Fungi were more susceptible to treatment than bacteria in a variety of community traits (alpha, beta diversity, and network topological features). The N and W factors act antagonistically to affect fungal alpha diversity, and the interaction effect was detected significant for the dry season. The topological features of the meta-community (containing both bacteria and fungi) network overrode the alpha and beta diversity of bacterial or fungal communities in explaining the variation of soil enzyme activities. The associations between Ascomycota fungi and Gammaproteobacteria or Alphaproteobacteria might be important in mediating the inter-kingdom interactions. In summary, our results suggested that fungal communities were more sensitive to N and W factors (and their interaction) than bacterial communities, and the treatments' effects were more prominent in the dry season, which may have great consequences in soil processes and ecosystem functions in subtropical forests.

Response of Soil Enzyme Activities to Natural Vegetation Restorations and Plantation Schemes in a Landslide-Prone Region

Soil enzyme activities in different plantation types and land use patterns could indicate changes in soil quality. This research was aimed at exploring the dynamics of soil enzyme activities involved in carbon, nitrogen and phosphorus cycling, and their responses to changes in soil physicochemical properties resulting from natural vegetation restorations and plantation schemes. Knowing about the effects of soil physicochemical properties on soil enzyme patterns is crucial for understanding ecosystem functions and processes. The study selected four main land-use types (natural forestland, natural grassland, artificial forestland, and artificial grassland) and one control plot (bare land) in the West Qinling Mountains, China, which is a typical landslide region. We collected the soil samples from each land use type and tested their physicochemical properties and enzyme activities compared with control land. The results showed that both natural vegetation restoration and artificial plantation schemes have significant effects on enzyme activities. Soil physicochemical properties explained 92.2% of the variation in soil enzyme activities for natural vegetation restoration, while it only explained 77.8% of the variation in soil enzyme activities for plantation schemes. Furthermore, natural vegetation had a greater effect than the plantation schemes on soil enzyme activities.

Effects of nitrogen addition on soil microbial biomass and enzyme activities of Pinus massoniana-Quercus variabilis mixed plantations in the Three Gorges Reservoir Area

We examined the effects of nitrogen addition (0, 30, 60, and 90 kg N·hm-2·a-1) to soil microbial biomass, enzyme activities, and nutrient contents of the Pinus massoniana-Quercus variabilis mixed plantations in the Three Gorges Reservoir Area, with the aim to provide a theoretical basis for predicting soil carbon dynamics under the background of continuously increasing atmospheric nitrogen deposition in this area. The results showed that nitrogen addition at all levels led to a significant increase of the contents of organic carbon, total nitrogen, microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), and microbial biomass phosphorus (MBP) in the forest soil, while a decrease of soil pH-value, and no significant effect on the total phosphorus content. Nitrogen addition increased the activities of β-1-4 glucosidase (BG), cellobiose hydrolase (CB), acid phosphatase (AP), N-acetylglucosaminosidase (NAG) and peroxidase (POD), while inhibited that of polyphenol oxidase (PPO). There was a significant seasonal variation in soil oxidase activities, in which the peroxidase activity was higher in May and August, and the polyphenol oxidase activity was the highest in August. Soil enzyme activities were significantly correlated with soil moisture and the contents of soil nutrients, MBC, MBN, and MBP. The variation of soil enzyme activities was caused by the comprehensive effects of multiple factors. The redundancy analysis (RDA) showed that the contents of total soil nitrogen and MBC were the main environmental factors driving soil enzyme activities. The continuous increase of atmosphere nitrogen deposition would lead to soil acidification and promote the turnover of soil organic carbon and nutrient cycling in the Pinus massoniana-Quercus variabilis mixed plantations of the study area.

Soil enzyme activities of typical plant communities after vegetation restoration on the Loess Plateau, China

Soil enzyme activities can indicate soil quality due to the catalyst roles enzymes play in various soil biochemical processes. However, little is known about the variations in soil enzyme activities among different plant communities with diverse environmental conditions. Here, the activities of four soil enzymes, catalase (CA), urease (UA), polyphenol oxidase (POA) and saccharase (SA), were investigated in shrub lands, forest lands and abandoned cropland on the Loess Plateau, China. Soil microbial biomass (MB) that contained bacteria, fungi and actinomycetes was also analyzed to determine the variations in enzyme activities. The results showed that soil enzyme activities varied significantly among different plant communities. Land uses, climate factors, topography and soil properties are all related to variations in enzyme activities. Specifically, soil properties including soil nutrients and MB were stable driving factors. With increasing soil MB, UA increased linearly, but CA, POA and SA increased exponentially, which might have resulted from soil nutrient deficiencies. Different plant communities with diverse microbial metabolisms performed differently in terms of soil enzyme activities, for example, in comparison to the other studied species, Hippophae rhamnoides had the greatest advantages and could improve the soil environment more effectively. Therefore, we suggest that the afforestation of Hippophae rhamnoides is an appropriate scenario for vegetation restoration in the typical hilly region of the Loess Plateau. AbbreviationsUnlabelled TableCAcatalase activityUAurease activityPOApolyphenol oxidase activitySAsaccharase activityMBmicrobial biomassSLshrub landFLforest landACabandoned croplandMATmean annual temperatureMAPmean annual precipitationSOCsoil organic carbonTNtotal nitrogenANavailable nitrogenTPtotal phosphorousAPavailable phosphorousTKtotal potassiumAKavailable potassium

Variations in Soil Enzyme Activities and Microbial Communities along an Altitudinal Gradient on the Eastern Qinghai–Tibetan Plateau

The Qinghai–Tibetan Plateau is the highest plateau in the world and is sensitive to climate change. The dynamics of soil enzyme activities and microbial communities are good indicators of alpine biochemical processes during warming. We collected topsoil (0–10 cm) and subsoil (10–20 cm) samples at altitudes of 3200–4000 m; determined the activities of β-1,4-glucosidase (BG), cellobiohydrolase (CBH), β-1,4-N-acetyl-glucosaminidase (NAG) and acid phosphomonoesterase (PME); and performed Illumina 16S rRNA high-throughput sequencing. We found that the soil carbon (total organic carbon and dissolved organic carbon) and nitrogen (total nitrogen and dissolved organic nitrogen) fluctuated with altitude in both the topsoil and subsoil, whereas the dissolved phosphorus continuously decreased with the increasing altitude. BG and CBH decreased from 3200 to 3600 m and increased from 3800 to 4000 m, with the lowest levels occurring at 3600 m (topsoil) and 3800 m (subsoil). NAG and PME showed similar fluctuations with altitude, with the highest levels occurring at 3400 m and 4000 m in both the topsoil and subsoil. Generally, the altitudes from 3600 to 3800 m were an ecological transition belt where most of the nutrients and enzyme activities reached their lowest levels. All of the alpine soils shared similar dominant phyla, including Proteobacteria (32.7%), Acidobacteria (30.2%), Actinobacteria (7.7%), Bacteroidetes (4.4%), Planctomycetes (2.9%), Firmicutes (2.3%), Gemmatimonadetes (2.0%), Chloroflexi, (1.2%) and Nitrospirae (1.2%); Gemmatimonadetes and Verrucomicrobia were significantly affected by soil depth and Planctomycetes, Firmicutes, Gemmatimonadetes, Nitrospirae, Latescibacteria and Armatimonadetes were significantly affected by altitude. In addition, nutrient availability, enzyme activity and microbial diversity were higher in the topsoil than in the subsoil, and they had more significant correlations in the subsoil than in the topsoil. Our results provide useful insights into the close linkages between soil nutrient cycling and microbial activities on the eastern Qinghai–Tibetan Plateau, and are of great significance for further assessing the long-term impact of environmental changes in the alpine ecosystems.

Biostimulating Effects of Disintegrated Waste Activated Sludge on Soil Enzyme Activities

Sludge disintegration methods are used in a variety of applications to enhance sludge characteristics or bring about a reduction in solid content of sludge. Hydrodynamic cavitation is one of the mechanical disintegration methods used on waste-activated sludge, and its efficiency has been investigated in recent years. In this study, the possible use of waste-activated sludge disintegrated by hydrodynamic cavitation and chemically assisted hydrodynamic cavitation as a soil amendment was evaluated by an incubation procedure. Possible biostimulating effects were assessed by monitoring the variations in soil enzyme activities. The obtained results indicated that sludge solubilization was effectively performed with respect to soluble chemical oxygen demand, soluble total Kjeldahl nitrogen and soluble total phosphorus. According to the incubation study, the biostimulating/bioremediating properties of waste-activated sludge were significantly improved by the applied methods. Especially after a 60-day incubation period, the levels of urease, alkaline phosphatase, β-glucosidase and dehydrogenase activities in soils applied with a high dose of disintegrated sludge were significantly higher than the levels in raw sludge-amended soils. Consequently, it is thought that mechanically and chemically disintegrated waste-activated sludge with reduced numbers of indicator bacteria can be considered as a way of soil amendment to rehabilitate the quality of environmentally stressed soils.

三峡库区马尾松人工林土壤酶活性和微生物生物量对氮添加的季节性响应

以三峡库区马尾松人工林为对象，分析土壤微生物生物量、酶活性和养分含量对氮添加的初期响应规律，为预测该地区在大气氮沉降持续增加的背景下森林土壤的季节动态提供参考。结果表明：氮添加初期，中氮水平（60 kg hm^-2 a^-1）的氮添加处理使得各季节土壤β-1-4葡萄糖苷酶、N-乙酰氨基葡萄糖苷酶、酸性磷酸酶、多酚氧化酶、过氧化物酶活性均增加，高氮（90 kg hm^-2 a^-1）水平的添加处理增加了土壤有机碳、全氮和微生物生物量碳、氮、磷的含量和酸性磷酸酶及多酚氧化酶活性，降低了土壤pH值、全磷含量和β-1-4葡萄糖苷酶及N-乙酰氨基葡萄糖苷酶活性。土壤酶活性和微生物生物量存在明显的季节变化，秋季水解酶活性和微生物生物量碳、磷含量显著高于春夏两季，而氧化酶活性和微生物生物量氮含量则是春夏季较高。土壤酶活性与季节、土壤含水量、养分含量及微生物生物量碳氮磷含量存在显著的相关性，酶活性变化是多因子综合作用的结果，冗余分析表明土壤含水量、微生物生物量碳、氮、磷和全氮是驱动土壤酶活性的主要环境因子。氮沉降的持续增加会加速当地马尾松人工林土壤腐殖质的形成，增加有机碳的积累，导致土壤酸化，并产生磷限制。;Anthropogenic nitrogen (N) enrichment is a concern worldwide, as it affects almost every aspect of ecosystem function and composition. Many nitrogen (N) addition experiments have been well documented to decrease plant biodiversity across various terrestrial ecosystems. However, such generalizations about the impacts of nitrogen addition on soil enzyme activities and microbial biomass are lacking, especially in the Three Gorges Reservoir area, as a key sensitive ecological barrier of the middle and lower reaches of the Yangtze River. Therefore, we conducted nitrogen addition experiments in February 2019 in Pinus massoniana plantation in the Three Gorges Reservoir area of subtropical China. Soil samples were collected from three control plots (N_CK), three low-nitrogen addition plots (N_low), three middle-nitrogen addition plots (N_middle), three high-nitrogen addition plots (N_high) in May, August and November, 2019. We studied the soil enzyme activities, microbial biomass and nutrient content in response to nitrogen addition, which provided a theoretical basis for predicting soil seasonal dynamics in an increasing atmospheric nitrogen deposition background in the Three Gorges Reservoir area. The results show that, in the early stage of nitrogen addition, the medium nitrogen (60 kg hm^-2 a^-1) treatment increased the activities of β-1-4 glucosidase (BG), N-acetylglucosaminosidase (NAG), acid phosphatase (AP), polyphenol oxidase (PPO) and peroxidase (POD); the high nitrogen (90 kg hm^-2 a^-1) treatment increased the contents of soil organic carbon, total nitrogen, microbial biomass carbon (MBC), nitrogen (MBN), phosphorus (MBP), and the activities of AP, PPO, while decreased the soil pH, total phosphorus content and the activities of BG and NAG. There were significantly seasonal differences between soil enzyme activities and microbial biomass. Hydrolase activities, MBC and MBP contents in autumn were significantly higher than those in spring and summer, while oxidase activities and MBN contents were higher in spring and summer. Soil enzyme activities were significantly correlated with season, soil moisture content, soil nutrient, MBC, MBN, MBP. The change of soil enzyme activities is due to the comprehensive action of multiple factors. Redundancy analysis (RDA) showed that soil moisture content, MBC, MBN, MBP and total N greatly accounted for the variation in soil enzyme activities. The increasing nitrogen deposition will accelerate the formation of soil humus, increase organic carbon accumulation, lead to soil acidification, and produce phosphorus limitation in the local Pinus massoniana plantation.

川西亚高山不同林龄粗枝云杉人工林土壤微生物生物量及酶活性

林分结构随林龄增加发生变化，致使土壤微环境变化，进而对土壤微生物生物量和酶活性产生直接或间接影响。以川西亚高山米亚罗林区25、40、50、60年生粗枝云杉（Picea asperata）人工林表层（0-20 cm）土壤为研究对象，分析不同林龄表层土壤微生物生物量碳（MBC）、氮（MBN）和酶活性的变化以及驱动土壤酶活性变化的主要环境因子，为人工林生态系统恢复效果评价及经营管理提供科学依据。结果表明：随着林龄的增加，MBC和MBN先上升后下降，在40年生达到最大；β-葡萄糖苷酶（βG）、β-N-乙酰氨基葡萄糖苷酶（NAG）和多酚氧化酶（PHO）活性与微生物生物量碳氮变化趋势相似，其中βG、NAG活性在50年生人工林达到最大，PHO活性于40年生人工林达到最大；50年生人工林过氧化物酶（PEO）活性显著低于其他林龄人工林；纤维素水解酶（CBH）活性随林龄增加而显著增加。冗余分析显示，碱解氮（AN）、pH和可溶性有机碳（DOC）是影响土壤酶活性变化的主导因子，分别解释了土壤酶活性变异的65.4%、9.7%和7.6%。综上可知，林龄对粗枝云杉人工林表层土壤微生物生物量和酶活性变化产生了显著影响，60年粗枝云杉林地力呈现衰退态势。为此，可对近60年的粗枝云杉人工林增加碳氮元素（尤其是氮素）的输入，以提升土壤质量和酶活性。;Stand structure changes with forest age caused the variation of soil microenvironment, which can directly or indirectly affect soil microbial biomass carbon and nitrogen, and soil enzyme activities. To better understand the change characteristics of soil microbial biomass contents and enzyme activities along an age sequence of spruce plantations, this study was conducted to evaluate the theoretical basis for restoration and effective management of subalpine plantations. In this study, Picea asperata plantations of various ages (25, 40, 50, and 60 years old) were selected in Miyaluo forest area of western Sichuan, China. The soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), available nitrogen (AN) and pH, microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), dissolved organic carbon (DOC), dissolved organic nitrogen (DON) and light fraction organic carbon (LFOC), soil enzyme activity index(β-glucosidase, βG; Cellulose hydrolysis, CBH; β-N-acetylglucosaminidase, NAG; Phenol oxidase, PHO and Peroxidase, PEO) in 0-20 cm soil was measured,respectively. The results showed that the MBC and MBN increased up to 40 years, and then decreased with the increase of age. There was a similar trend in changes of the activities of βG, NAG and PHO, while βG and NAG were highest at 50 years, and PHO was highest at 40 years. PEO activity of 50 years was significantly lower than other plantations. The activity of CBH increased with the increasing age of Picea asperata plantation stands. Redundancy analysis (RDA) indicated that AN, pH and DOC were main influence factors of soil enzyme activities in the top-layer soil, accounted for 65.4%, 9.7% and 7.6% of total variation of soil enzyme activities, respectively. Overall, our results suggested that the growth of Picea asperata had a significant effect on soil microbial biomass and enzyme activities. The soil fertility in 60 years of Picea asperata plantation was the lowest in all Picea asperata plantations. Therefore, we can increase carbon and nitrogen elements (especially nitrogen) devotion to improve soil quality and enzyme activities in Picea asperata plantations nearly 60 years.

Vegetation type rather than climate modulates the variation in soil enzyme activities and stoichiometry in subalpine forests in the eastern Tibetan Plateau

Soil extracellular enzymes catalyze the rate limiting steps of organic matter decomposition, and enzyme stoichiometry has been used to reflect microbial resource acquisition strategies. However, the patterns and key driving factors of soil enzyme activities and stoichiometry in subalpine forests, which are areas sensitive to global changes, remain unclear. In this study, rhizosphere and bulk soils along two environmental gradients in the subalpine forests of Gongga Mountain, in the eastern Tibetan Plateau, including (1) a horizontal chronosequence with different vegetation types but a similar climate and (2) a vertical elevation gradient with the same vegetation type but different climates, were sampled during the growing and nongrowing seasons. The activities and stoichiometry of soil enzymes related to the microbial acquisition of carbon (C) (β-1,4-glucosidase, BG), nitrogen (N) (β-1,4-N-acetylglucosaminidase, NAG) and phosphorus (P) (acid phosphomonoesterase, AP) were analyzed to reveal their responses to environmental gradients. The results showed that enzyme activities and stoichiometry varied significantly among vegetation types, but were less affected by climate and root proximity. BG activity and ratios of BG to nutrient-acquiring enzymes were significantly higher in broadleaf forests than in coniferous forests. The differences in enzyme stoichiometry between vegetation types were weakly related to the microbial nutrient status (represented by the ratio of soil to microbial element stoichiometry) but might be explained by the higher proportion of ectomycorrhizal fungi in coniferous forests compared to broadleaf forests. The results of this study indicate that vegetation type was a major factor regulating soil enzyme activities and stoichiometry in the subalpine forests, possibly via its influences on plant-associated microbial communities.

Soil pH and C/N ratio determines spatial variations in soil microbial communities and enzymatic activities of the agricultural ecosystems in Northeast China: Jilin Province case

Soil microbes and their functions play important roles in the sustainable development of agricultural ecosystems but are vulnerable to climate change and human activity. We measured the contents of microbial phospholipid fatty acids (PLFAs) and enzymatic activities in various soil types (dark-brown soil, albic soils, black soil, chestnut soil, and chernozem) in three climatic zones (humid zone, subhumid zone, and semi-arid zone) of the Songnen Plain in northeastern China. The objectives were to investigate the spatial variations in community structure of soil microbes and to evaluate the functional potential of the microbes in croplands in northeastern China. The C-acquiring activities were highest in the chernozem soil of the semi-arid zone, but N-acquiring and P-acquiring activities and peroxidase were highest in the albic soil of the humid and subhumid zone. Phosphorus deficiencies were indicated by the reduced ratios of N- relative to P-acquiring activity and C-relative to P-acquiring activity in the croplands compared with the global average. Different groups of PLFA contents were highest in the dark-brown soil of the humid zone and the chestnut soil of the semi-arid zone. The community compositions of the microbes varied amongst the soil types and climatic zones, with the ratios of fungi/bacteria and Gram-positive/Gram-negative bacteria highest in chernozemic soil of the semi-arid zone. The variations in soil enzyme activities and microbial community structure were more dependent on climate conditions than soil type. Soil pH, soil organic C content, and the C/N ratio were the most important factors affecting the spatial patterns of the soil enzyme activities and microbial-community compositions across soil types and climatic zones. Mean annual precipitation and clay content strongly influenced enzymatic activities and microbial-community compositions, respectively, when each variable was used as the only factor. Their effects, however, were negligible when combined with other factors. Balanced chemical fertilizer with scientific N-P-K ratio should be applied instead of only N fertilizers. The other combination of different conservational agricultural practices, such as application of organic fertilizer, not tilling, crop rotation, and intercropping, would be more beneficial for restoring the community compositions and functions of soil microbes and achieving sustainable agricultural development.

Different forms and rates of nitrogen addition show variable effects on the soil hydrolytic enzyme activities in a meadow steppe

The effects of mixed inorganic and organic nitrogen (N) addition on soil enzyme activities and the underlying mechanism remain unclear, especially in complex field conditions. We conducted a mesocosm experiment with two rates of N addition (10 and 20 g N m–2 year–1) and four ratios of N addition (inorganic N:organic N = 10:0, 7:3, 3:7 and 1:9) and measured enzyme activities, soil physicochemical properties, microbial biomass and vegetation indicators. Generally, soil enzyme activities involved in carbon (C), N and phosphorus cycling increased with the increase of N addition rate. Compared to the single inorganic N addition treatment, enzyme activities were highest under mixed N addition treatments, especially medium organic N addition. The variations in soil enzyme activities across different treatments were tightly linked to the soil microbial biomass C, dissolved organic C and soil pH. These findings provide a good understanding of the response trends of soil hydrolytic enzyme activities in a meadow steppe to changes in N deposition rate and form.

连栽杉木人工林参与土壤碳氮转化过程酶活性及其与土壤理化因子的相关性

PDF HTML阅读 XML下载 导出引用 引用提醒 连栽杉木人工林参与土壤碳氮转化过程酶活性及其与土壤理化因子的相关性 DOI: 10.5846/stxb201811252551 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（41603081，31700378）；福建省科技厅高校联合资助面上基金项目（2017J01458） Soil carbon and nitrogen transformed enzyme activities in continuously cultivated Chinese fir (Cunninghamia lanceolate) plantations and their correlations with soil physicochemical factors 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:选取福建三明不同连栽代数杉木人工林（一代、二代、三代）及格氏栲天然林为研究对象，运用冗余分析法研究不同林地土壤理化性质、养分含量与参与碳，氮转化过程酶活性之间的相互关系，以探究中亚热带连栽杉木人工林土壤酶的季节变化及其影响因素，为揭示杉木人工林养分循环特点和林地土壤质量评价提供依据。结果表明：连栽杉木人工林地土壤pH显著低于天然林，但一、二、三代杉木林间无显著差异。12月份土壤全碳、全氮含量在不同连栽代数杉木林中无显著差异，并且二代和三代林土壤全碳、全氮含量均显著高于天然林（P<0.05）；6月份杉木三代林土壤全碳含量显著高于一代林（P<0.05），但与二代林和天然林无显著差异。12月份土壤铵态氮和硝态氮含量在一、二、三代杉木林间无显著差异。6月份杉木一代林土壤硝态氮含量显著高于二代林和天然林（P<0.05），但与三代林无显著差异。12月份天然林土壤脲酶活性显著高于连栽杉木人工林（P<0.05），而一、二、三代杉木林土壤脲酶活性无显著差异；杉木一代、二代林和天然林土壤天冬酰胺酶活性无显著差异，均显著高于三代林（P<0.05）。冗余分析表明，土壤含水量、NO3--N含量和pH对酶活性的影响较大，它们与土壤天冬酰胺酶、β-葡萄糖苷酶（BG）、和蛋白酶（protease）呈显著正相关，但与土壤N-乙酰氨基葡萄糖苷酶（NAG）呈显著负相关。本研究说明杉木林进入成熟林-过熟林阶段后，不同连栽代数林地许多土壤理化指标及酶活性均有不同程度恢复，而且它们受季节因素影响很大，建议今后加强土壤酶活性对环境变化响应的长期综合监测。 Abstract:This study aims to investigate the seasonal changes of soil carbon and nitrogen-transformed enzyme activities and their driving factors in successive rotations of subtropical Chinese Fir (Cunninghamia lanceolate) plantation. The results would provide basis for assessing nutrient cycling and soil quality in forest. Through canonical redundancy analysis (RDA) the relationships between soil physical properties, nutrient conditions, and enzyme activities were analyzed in different generations of Chinese fir plantation (FRP, SRP, TRP) and Castanopsis Kawakamii forest (NF) in Fujian province, China. A significant decrease of soil pH was observed in Chinese fir plantation compared with NF, but no significant changes were found between FRP, SRP, and TRP. In December, there was no significant difference on soil total carbon and nitrogen among different generations of Chinese fir plantation, and the SRP and TRP were significantly higher than the NF (P<0.05). In June, soil total carbon of TRP was significantly higher than that of FRP (P<0.05), but not significantly different from that of SRP and NF. In December, there was no significant difference on soil NH4+-N and NO3--N among different generations of Chinese fir plantation. In June, soil NO3--N of FRP was significantly higher than that of SRP and NF (P<0.05), but not different from that of TRP. Soil urease activity of NF was significantly higher than that of FRP, SRP, and TRP, but no significant difference was found among FRP, SRP, and TRP in December. Soil asparaginase activity of FRP, SRP, and NF were significantly higher than that of TRP (P<0.05), but no significant difference was found among FRP, SRP, and NF. The RDA showed that soil moisture, NO3--N, and pH made significant contributions to variations of soil enzyme activities, especially positively related to the activities of soil asparaginase, β-glucosidase (BG), and protease, but negatively related to soil N-acetyl-β-D-glucosaminidase (NAG). The soil physiochemical properties and enzyme activities in mature and over-mature Chinese fir plantations recovered to different degrees compared with the natural forest, and their variations were largely influenced by the seasonal changes. Additionally, a long-term observation on soil enzyme activities in response to the environmental changes is recommended. 参考文献 相似文献 引证文献

Biochar mitigates the effect of nitrogen deposition on soil bacterial community composition and enzyme activities in a Torreya grandis orchard

Increased reactive N deposition has widespread effects on terrestrial ecosystems, such as biodiversity loss, soil acidification, as well as stimulated plant growth. Empirical studies show that biochar often affects soil quality, crop productivity, soil microbial community composition and enzyme activities. However, the effect of biochar addition on forest soil bacterial community along with enzyme activities under nitrogen (N) deposition and its related mechanisms have not been well studied yet. Therefore, a 2-year field study was conducted to investigate the effects of biochar amendment (0, 20, 40 kg biochar ha−1 yr−1) on soil nutrients, enzyme activities, and bacterial community in a Torreya grandis orchard under different levels of N deposition (0, 30, 60 kg N ha−1 yr−1). N deposition significantly increased soil nutrients availability, such as N, phosphorus (P) and potassium (K), while biochar amendment led to significant increase in soil pH, organic carbon (SOC), total N (TN), total P (TP), available P (AP) and available K (AK). Both N deposition and biochar amendment significantly decreased the soil microbial biomass carbon (MBC), altered soil microbial community and enzyme activities significantly. Biochar addition increased the relative abundance of phylum Proteobacteria under different levels of N deposition, but had variable effect on Acidobacteria groups. Non-metric multidimensional scaling (NMDS) indicated that biochar amendment can mitigate the effect of N deposition on soil bacterial community composition and enzyme activities. Soil pH and SOC played an important role in shaping soil bacterial community composition, while available AP and AK contents significantly related to the variation of soil enzyme activities. Structure equation modeling (SEM) revealed that N deposition had negative effect on soil enzyme activities while biochar amendment can mitigate this negative effect through increasing AP content. Our result suggests that biochar amendment can mitigate the alteration of soil bacterial community and enzyme activities induced by N deposition, and this mitigation effect was linked to the alteration of soil physicochemical properties, especially the increased AP content. Thus, biochar amendment could be a promising way to develop sustainable forest management under increasing N deposition.

Temporal Variations in Soil Enzyme Activities and Responses to Land-Use Change in the Loess Plateau, China

Variability in soil enzyme activity may have important implications for the knowledge of underground ecosystem functions driven by soil extracellular enzymes. To illustrate the temporal variation in soil enzyme activity after afforestation, we collected soil samples during different vegetative growth periods in three Caragana korshinskii Kom. stands of different ages (20, 30, and 40 years) and in a slope cropland in the Loess Plateau. These samples were used to analyze the catalase, sucrase, urease and alkaline phosphatase activities, the soil water content and the available soil nutrients (i.e., dissolved organic carbon, dissolved organic nitrogen, and available phosphorus). The results illustrated that the soil enzyme activities significantly increased following afforestation and varied with temporal variation. Overall, soil enzyme activities were higher in June and August, particularly, and both alkaline phosphatase and sucrase were more sensitive to temporal variation than the other two enzymes. In addition, redundancy analysis showed that soil enzyme activities were greatly correlated with soil nutrients, especially for dissolved organic carbon and dissolved organic nitrogen. Therefore, the results highlighted the importance of soil enzyme activities to soil nutrients under temporal variation following afforestation in the Loess Plateau, which may have practical significance for forest managers’ fertilization management of plantation in different seasons and different stand ages.

Variations in carbon‐decomposition enzyme activities respond differently to land use change in central China

AbstractThe turnover of soil organic carbon (SOC) is primarily regulated by extracellular enzymes secreted by the microorganism. However, how soil C‐decomposition enzymes respond to different land use change remains unclear. Here, we conducted a study to explore seasonal variations in C‐decomposition enzyme activities including hydrolases (α‐glucosidase, β‐glucosidase, cellobiohydrolase, and β‐xylosidase) and oxidases (polyphenol oxidase and peroxidase) in woodland, shrubland, cropland, and adjacent uncultivated soils in central China. Soil dissolved organic C (DOC), SOC, labile C (LC), recalcitrant C (RC), soil C recalcitrance index (RIC: RC/SOC ratio), pH, soil moisture, and temperature were also investigated. Both afforested and cropland averaged higher hydrolase and oxidase activities compared with the uncultivated land, with higher levels of enzyme activities in topsoils than deep soils. By comparing with the uncultivated land, higher hydrolytic enzyme activities in afforested soils were mainly attributed to higher DOC and LC contents, whereas higher hydrolase activities in cropland soils were possibly due to lower C:nitrogen (N) ratios and agricultural disturbance (i.e., fertilization and tillage). In contrast, two oxidases activities were the highest in the cropland, which might be attributed to higher RIC and lower C:N ratio. Cropland soils also averaged higher specific enzyme activities (i.e., enzyme activities per unit of SOC) compared with the afforested land, indicating fast C turnover rates in cropland. Seasonal variations in soil enzyme activities were primarily driven by soil temperature and pH. Overall, our results reveal the different underlying mechanisms between hydrolases and oxidases in response to types of land use change.

Seasonal variation of soil enzyme activities in relation to nutrient and carbon cycling in Senna alata (L.) Roxb invaded sites of Puducherry region, India

The present study is to understand the intrinsic ecological trait of invasive plant Senna alata relating to soil characteristics and seasonality distributed in the Puducherry region located under tropical climate. Plant biomass, soil parameters linked with soil enzyme activities are examined in six sites where S. alata is found growing. From the study, it is demonstrated that invasive species S. alata exhibits heterogeneity in invaded soil characteristics but variation in aboveground biomass (AGB) of S. aalata is not significant. Soil moisture and soil enzymes activities and AGB are significantly positively correlated whereas pH and EC negatively correlated. Seasonal variation in total nitrogen, phosphorus, and elements viz. Mg, Ca, and Na is inconsistent in their seasonality. Based on observations made and results obtained in the study, it is stated soil characteristics and their seasonality in the S. alata invaded soil is, site-specific resulting in heterogeneity; but such heterogeneity is not exhibited in AGB in six sites and it is, therefore, reported that such an idiosyncratic trait of S. alata is one of the potential traits influencing successful invasion by S. alata as mono-species population. The statistical analyses also confirmed the observation made. The outcome of the study would help to prepare management programmes to check spreading of invasive species so as to restore native plant diversity in and around Puducherry region.

Response of Soil Enzyme Activities and Their Relationships with Physicochemical Properties to Different Aged Coastal Reclamation Areas, Eastern China

Land reclamation transforms a tidal flat from a marine ecosystem to terrestrial ecosystem, which significantly changes the soil ecosystem process, affecting the soil enzyme activities. Soil enzyme is involved in almost all soil biochemical processes. Clarifying the relationship between soil physicochemical properties and soil enzyme activities can reveal the changes of soil quality after reclamation and provide a theoretical basis for the scientific regulation of the soil ecosystem. In this study, a total of 72 soil samples were collected from a coastal reclamation area with different years of reclamation (0, 7, 32, 40, and 63 a) in Rudong County. The changes in soil physicochemical properties and enzyme activities within different reclamation years were analyzed by classical statistical analysis, and the relationship between soil enzyme activities and physicochemical properties was analyzed using a redundancy analysis. The results showed that longterm land reclamation had significant effects on soil physicochemical properties and enzyme activities. pH and electrical conductivity showed a decreasing trend after reclamation, while the content of soil organic carbon, total nitrogen, and total phosphorus showed a trend of "rapidly accumulate-gradually consume-accumulate again" with increasing years of reclamation. Compared with the bare flat area (0 a), amylase, dehydrogenase, and acid phosphatase activity initially increased and then decreased with increasing years of reclamation, while urease and alkaline phosphatase activities were characterized by an increase-decrease-increase trend. Meanwhile, the enzyme activities within different reclamation ages were basically higher in surface soil than deep layers. Redundancy analysis revealed that the soil physicochemical properties explained 69.8% of the variation in soil enzyme activities, and an obvious relationship existed between pH, electronic conductivity, soil organic carbon, total nitrogen, total phosphorus, and soil enzyme activities (P<0.01). The order of importance of soil physicochemical properties to soil enzyme activities was as follows:total nitrogen > soil organic carbon > pH > total phosphorus > electronic conductivity.

Repeated treatments of ciprofloxacin and kresoxim-methyl alter their dissipation rates, biological function and increase antibiotic resistance in manured soil

The dissipation of ciprofloxacin (CIP, 1.0 and 10.0mg/kg) and kresoxim-methyl (KM, 1.0 and 2.0mg/kg) in manure-amended soil, the variations in soil enzyme activities and microbial functional diversities, and CIP-induced bacterial community tolerances were studied using a chromatographic analysis, enzyme colorimetric and titration analyses, and the BIOLOG EcoPlate method. Three successive treatments of individual and combined samples of CIP and KM at low and high concentrations were performed at 60d intervals. The dissipation half-life of CIP increased, but that of KM decreased in manured soil with treatment frequency; furthermore, the combined treatment altered the dissipation rates of CIP and KM. A stronger inhibitory effect on the activities of soil neutral phosphatase and urease was observed in the individual KM treatment than in the individual CIP treatment. A similar inhibitory trend was also found in soil neutral phosphatase activity in the combined treatment at high concentration compared to that at low concentration, but the activity of soil catalase was enhanced in the early stages of the KM or CIP treatments. Meanwhile, the inhibitory trend on the overall activity and functional diversity of soil microorganisms was observed in the individual KM or CIP treatment, and the combined treatment exerted a greater suppression effect than that in the individual treatment. Bacterial community resistance to CIP increased significantly with increasing treatment frequency and concentration, and furthermore antibiotic resistance developed faster in the combined treatment than in the individual treatment. It was concluded that the repeated treatments of CIP and KM could alter their dissipation rates and soil enzyme activities, suppress microbial functional diversity, and increase bacterial community resistance to CIP in manured soil.