Effect of forest thinning on soil net nitrogen mineralization and nitrification in a Cryptomeria japonica plantation in Taiwan

We investigated the effect of forest thinning on soil nitrogen mineralization, nitrification and transformation in a Cryptomeria japonica plantation at high elevation to provide basic data for forest management. We chose four study plots for control, light, medium and heavy thinning treatment, and three sub-plots for buried bag studies at similar elevations in each treatment plot to measure the net N mineralization and nitrification rates in situ. The contents of soil inorganic N(ammonium and nitrate) were similar between treatments, but all varied with season, reaching maxima in September 2003 and 2004. The seasonal maximum net Nmin rates after four treatments were 0.182, 0.246, 0.303 and 0.560 mg·kg-1·d-1 in 2003, and 0.242,0.258,0.411 and 0.671 mg·kg-1·d-1in 2004, respectively. These estimates are approximate with the lower annual rates of N mineralization for this region. Forest thinning can enhance net N mineralization and microbial biomass carbon. The percentage of annual rates of Nmin for different levels of forest thinning compared with the control plot were 13.4%, 59.8% and 154.2% in 2003, and 0.1%, 58.8% and 157.7% in 2004 for light, medium, and heavy thinning, respectively. These differences were related to soil moisture, temperature, precipitation, and soil and vegetation types. Well-planned multi-site comparisons, both located within Taiwan and the East-Asia region, could greatly improve our knowledge of regional patterns in nitrogen cycling.

Effect of Land Cultivation on Soil Nutrient Sedimentation in Water at Southern China

Soil erosion associated with land cultivation exerts a great impact on ecological environment.Such an impact is specific of land,crop,tillage,management and so on.This study aimed to investigate the effects of crop cultivation on water quality by comparing nutrient distribution in the sediment at Southern China.Two sedimentation sites adjacent to the uncultivated(S1)and cultivated upland(S2)were selected and samples were analyzed.Results showed that soil pH decreased with the increasing depth above 20 cm and then kept relatively stable of the both sediments.Soil organic matter,nitrogen and phosphorus contents decreased with the increasing depth.There was no significant difference between two sediments in organic matter and nitrogen contents,but the total phosphorus and extractable phosphorus contents in S2 were much higher than that in S1.The data indicated that soil eroded from S2 could possess much high potential to deteriorate water quality.Nutrient sedimentation can reflect the history of soil erosion and provide useful information for sustainable soil management and water conservation through improving cultivation and tillage measures.

Effects of Silicon Fertilization on Soil Chemical Properties and Phytolith Formation of Phyllostachys pubescens

Silicon is benefit to Gramineae plants in growth and resistance to various stresses.However,the effect of silicon fertilizer application on Phyllostachys pubescens is still not investigated yet.Phyllostachys pubescens Mazel ex J.Houz is one kind of Gramineae plants which distributes in a large area.In this study,a field experiment with five Si fertilizer application rates(0,125,250,375,and 500 kg ha-1)was setup in a Phyllostachys pubescens forest in China to examine the effects of Si fertilizer on bamboo Si and phytolith accumulation in fresh leaf and leaf litter.Results showed that Si application increased soil available Si content in deep layers.Si content of leaf-litter increased with the increasing level of Si fertilizer application rate,with the value ranging from 114.3 g kg^(−1)to 172.7 g kg^(−1),however,no significant difference was observed in fresh leaf,with the value ranging from 84.0 g kg^(−1)to 115.0 g kg^(−1).The phytolith contents of leaf-litter and fresh leaf were consistent with the Si contents,the phytolith content in leaf-litter of T4(500 kg ha^(−1))was 48.4%higher than the control,suggesting Phyllostachys pubescens exhibited an increasing carbon sink in phytolith when Si fertilizer applied,which is an effective way to increase long-term soil organic carbon storage in Phyllostachys pubescens forests with a suitable Si fertilization.

Legume Green Manuring Improves Soil Fertility and Plant Growth of Eucalyptus Plantation in South Subtropical China

Legume green manure is extensively planted to improve soil fertility in crop field.However,the application of legume in Eucalyptus plantation is still limited and depends on site specific and species.Therefore,the objective of this study was to determine the effects of green manure interplantation on soil fertility and plant growth of Eucalyptus plantation in a short term.A field experiment of one year was established to investigate the green manure growth,forest soil nutrients and Eucalyptus plant growth inter-planted with two legume species(Tephrosia candida,TC and Sesbania cannabina,SC)at south subtropical China.Legumes were inter-planted in linear among the tree space of Eucalyptus stand.Result showed that the green manure inter-plantation increased soil organic matter by 9.66%of TC and 18.44%of SC.Soil available nitrogen,phosphorus and potassium were improved significantly by the legume treatments as well.The increment of height and diameter at breast height of Eucalyptus during the experiment was significant in legume treatments.Thus,the timber volume increment was improved significantly by 46.81%of TC and 35.47%of SC compared with the control treatment.Therefore,the inter-plantation of legume green manure under the Eucalyptus plantation is effective to improve soil fertility and tree growth.Such a measure is potential and referenced for the sustainable forest management.

Nitrogen Release Characteristics of a Bag Controlled Release Fertilizer

Slow release fertilizers are designed to enhance crop yield and minimizing the loss of nitrogen(N)to environment.However,N release in leaching and loss in ammonia emission from bag controlled release fertilizers have not been previously evaluated under the standardized conditions in soil.Accordingly,a laboratory study was conducted to evaluate the characteristics of N release from a bag controlled fertilizer with 1,3,5 and 7 rows of hole(B-1,B-3,B-5,B-7)and a kraft bag without hole(B-W).The results showed that the amount of N leaching of B-1,B-3,B-5,B-7 and B-W were significantly lower than urea fertilizer without bag(U).The maximum N release from the fertilizers followed the order:U(83.16%)>B-7(54.61%)>B-5(54.02%)>B-W(51.51%)>B-3(48.87%)>B-1(38.60%)during the experimentation.Compared with U treatment,ammonia volatilization losses were significantly decreased by B-1,B-3,B-5,B-7 and B-W treatments.Based on N release and loss,a suitable bag with holes should be considered in practice when using the bag controlled fertilizer to meet an environment good objective.The evaluation method merits further study combined with field experiment.

毛竹的耐铝性研究

毛竹广泛分布于中国的南方的酸性土壤区域，那些区域是铝毒性的高风险地区。为了对毛竹对铝的抗性的进行评估，本文对相同生长进程下的毛竹和两个水稻栽培品种的种子萌发和根的延长生长进行了对比，并仔细观察了他们在各级不同铝的受力下的物理和生理的损害程度。结果表明：铝浓度增加至500μM时，毛竹种子萌发受到抑制，半致死浓度为2000μM。相比之下，水稻种子萌发并没有受到铝浓度的抑制，甚至在铝浓度为2000μM时。铝积累主要在根尖细胞壁和原生质体治疗时间的延长进入原生质体和／或随着铝浓度的增加，这种现象导致细胞凋亡。竹子的根表皮在2000μM铝浓度时存在显著的退化。总之，毛竹只对低浓度的铝具有抗性。

A Review of 2022 Publications in“Research in Ecology”

This year,there was a total of 17 publications published in form of articles,reviews,short communication and ed­itorial.These publications have been read by 3693 times and downloaded by 792 times within the year.The content of the publications contains many aspects of ecology,such as population distribution,fungi species,water ecosystem,plant diversity,machine learning methods,biodiversity,ecotourism,forest structure,biogeographic network,and so on.The authors come from Africa,Asia,America and Europe.Wherein the article entitled“Butterfly Diversity in Relation to Human-Impact Gradient in Outskirts of Kolk­ata,West Bengal,India”written by Mollah KB and Man­dal S[1]had a high view and download times.

A Challenge and Chance for Soil Ecology

Due to the excessive use of mineral resources,more greenhouse effect gases have been emitted into the atmosphere.The global warming effect induced by human activity has been intensified much more than ever before.Accordingly,ecology systems are being suffered significant changes over the world.Soil is one of our most important natural resources.Physically,soil is the crust surface of the earth that can supply nutrients and support for plant growth.It often determines the nature of the vegetation present and related animals in number and types.Soils provide habitats for a myriad of living organisms,from small mammals and reptiles to tiny insects to microscopic cells of unimaginable numbers and diversity.Moreover,soil plays an important role as an engineering medium in human-built ecosystems[1].Therefore,the understanding of soil and its response to the global warming is important for the harmony of human and environment.

Climatic effects on soil organic nitrogen fractions and amino acid chirality in paddy soils

Soil organic nitrogen(ON)accounts for more than 90%of the total nitrogen(TN)in paddy soils.Inadequate understanding of the different ON fractions in paddy soils and their corresponding bioavailability under different climatic conditions has constrained the development of appropriate nutrient management strategies for rice production.In this study,we applied a modified Bremner method coupled with high-performance liquid chromatography to characterize how soil ON fractions and amino acid chirality varied under different climatic conditions at five typical rice production sites along a latitudinal gradient.According to the results,climate had no obvious influence on TN,nitrogen(N)form,and individual amino acid contents.However,the proportions of various N forms in TN had linear relationships with annual mean temperature(AMT),with high correlation coefficient(r)values.Amino acid components also exhibited similar trends,with r as high as 0.85.Most notably,consistent linear relationships were observed between the D/L ratios of several amino acids and AMT in paddy soils(r=0.18–0.92).Findings of this study provide insights into ON and amino acid dynamics in paddy soil systems under intensive production along climate gradients.

Effect of cultivation time on soil heavy metal accumulation and bioavailability in Phyllostachys praecox stands

Phyllostachys praecox is a bamboo species cultivated for edible shoots under intensive management.However,the potential pollution risk of heavy metals in bamboo soils is not clear under the intensive management for a long term.The objective of this study was to evaluate the effect of cultivation time on soil heavy metal accumulation and bioavailability in bamboo stands subjected to intensive management.Soil samples were collected from a chronosequence of bamboo stands which had been cultivated for 0,1,2,4,8,and 10 years in Lin’an,Zhejiang Province of China.Eight heavy metals(Cu,Zn,Pb,Ni,Cr,Cd,As,and Hg)present in the soil were selected,and their potential pollution risk was evaluated by chemical speciation analysis.Possible heavy metal sources were explored using multivariate and cluster analysis.Our results showed that Zn,Cu,Hg,and Cd contents in the soil increased with the cultivation time,while Ni,Cr,Pb,and As levels were similar among all stands.Furthermore,the bioavailabilities of all analyzed heavy metals increased with the cultivation time.Multivariate and cluster analysis showed that sources of Ni,Cr,Pb,and As were likely lithogenic in origin,whereas input of Zn,Cu,Hg,and Cd was mainly due to cultivation practices.Current bamboo management strategies raised the potential risks of heavy metal pollution in bamboo shoots in the long term.Soil acidification in P.praecox stands induced by intensive cultivation should be controlled since it stimulated and improved the bioavailability of heavy metals.Appropriate management strategies should thus be adopted to ensure safe and sustainable production of bamboo shoots.

Effects of biochar amendments on soil water retention characteristics of red soil at south China

Biochar has been extensively used for the improvement of soil water retention.However,the effects of various biochars were not well determined.The objectives of this study were to investigate the effects of three biochars[biochars made from bamboo(Bambusaceae),rice straw(Oryza sativa),and tobacco stem(Nicotiana L.)]on soil physical properties and the water retention characteristics of red soil at southeast China.The air-dried soil samples were mixed with ratios of 2%,5%,and 10%(w w^(−1))BC(bamboo biochar),RC(rice straw biochar),and TC(tobacco biochar),respectively,and evaluated for changes in soil bulk density(BD),soil saturated water content,field capacity,capillary porosity and soil hygroscopic coefficient.The results showed that BD decreased significantly with the application of the three types of biochar,total soil porosity and capillary porosity increased with the increase of the biochar ratio.The soil hygroscopic coefficient,wilting moisture capacity,saturated water content,and field capacity were significantly affected by the application of the three types of biochar.Compared with the other two treatments,the BC showed the best effects on soil water characteristics.BC treatments with addition ratios of 2%,5%,and 10%significantly decreased BD by 6.55%,18.03%,and 36.07%,respectively.Moreover,saturated water content and field capacity were increased by BC.BC treatments significantly increased the readily available water by 32.65%,42.49%,and 50.01%,respectively.However,the increased non-readily available water induced by the high ratio of biochar addition was not easily utilized by plants.Our results suggested that the biochar amendment can improve soil structure,decrease soil BD,boost soil porosity and capillary porosity,and increase soil moisture constant,and 2-5% of BC was recommended in the field condition.

Periphytic biofilms-mediated microbial interactions and their impact on the nitrogen cycle in rice paddies

Rice paddies are unique waterlogged wetlands artificially constructed for agricultural production.Periphytic biofilms(PBs)at the soil–water interface play an important role in rice paddies characterized by high nutrient input but low utilization efficiency.PBs are composed of microbial aggregates,including a wide variety of microorganisms(algae,bacteria,fungi,protozoa,and metazoa),extracellular polymeric substances and minerals(iron,aluminum,and calcium),which form an integrated food web and energy flux within a relatively stable micro-ecosystem.PBs are crucial to regulate and streamline the nitrogen cycle by neutralizing nitrogen losses and improving rice production since PBs can serve as both a sink by capturing surplus nitrogen and a source by slowly re-releasing this nitrogen for reutilization.Here the ecological advantages of PBs in regulating the nitrogen cycle in rice paddies are illustrated.We summarize the key functional importance of PBs,including the intricate and delicate community structure,microbial interactions among individual phylotypes,a wide diversity of selfproduced organics,the active adaptation of PBs to constantly changing environments,and the intricate mechanisms by which PBs regulate the nitrogen cycle.We also identify the future challenges of microbial interspecific cooperation in PBs and their quantitative contributions to agricultural sustainability,optimizing nitrogen utilization and crop yields in rice paddies.