我国黄竹天然竹林资源现状和保护策略分析

黄竹在我国生长于热带北缘湿热地区,在澜沧江中下游河谷地区形成大面积的天然林分,是我国面积最大、最具代表性的天然热带性大型丛生竹林。由于我国绝大部分天然黄竹林不属于自然保护区和天然林保护范围,其资源的开发和利用没有科学的规划,近年来天然黄竹林群落和以黄竹林为基础的植被环境破坏严重,亟需对其资源进行保护研究。本文对黄竹的资源现状和面临的问题进行了调查和分析,提出了黄竹种质资源的保护建议。     

Interactive effects of biochar addition and elevated carbon dioxide concentration on soil carbon and nitrogen pools in mine spoil

Purpose

This study aimed to assess the effects of biochar on improving nitrogen (N) pools in mine spoil and examine the effects of elevated CO₂ on soil carbon (C) storage.

Materials and methods

The experiment consisted of three plant species (Austrostipa ramossissima, Dichelachne micrantha, and Lomandra longifolia) planted in the N-poor mine spoil with application of biochar produced at three temperatures (650, 750, and 850 °C) under both ambient (400 μL L^?1) and elevated (700 μL L^?1) CO₂. We assessed mine spoil total C and N concentrations and stable C and N isotope compositions (δ¹³C and δ¹⁵N), as well as hot water extractable organic C (HWEOC) and total N (HWETN) concentrations.

Results and discussion

Soil total N significantly increased following biochar application across all species. Elevated CO₂ induced soil C loss for A. ramossissima and D. micrantha without biochar application and D. micrantha with the application of biochar produced at 750 °C. In contrast, elevated CO₂ exhibited no significant effect on soil total C for A. littoralis, D. micrantha, or L. longifolia under any other biochar treatments.

Conclusions

Biochar application is a promising means to improve N retention and thus, reduce environmentally harmful N fluxes in mine spoil. However, elevated CO₂ exhibited no significant effects on increasing soil total C, which indicated that mine spoil has limited potential to store rising atmospheric CO₂.

     

Cumulative effects of repeated chlorothalonil application on soil microbial activity and community in contrasting soils

Purpose

Chlorothalonil (CTN) has received much attention due to its broad-spectrum antifungal function and repeated applications in agriculture production practice. An incubation experiment was conducted to study the accumulating effects of CTN repeated application on soil microbial activities, biomass, and community and to contrast the discrepancy of effects in contrasting soils.

Materials and methods

Different dosage CTN (5 mg kg^?1, T1, and 25 mg kg^?1, T5) was applied into two contrasting soils at 7-day intervals. Soil samples were taken 7 days after each application to assess soil enzyme activities and gene abundances. At the end of incubation, the soil samples were also taken to analyze microbial communities in the two test soils.

Results and discussion

Soil fluorescein diacetate hydrolysis (FDAH) and urease activities were inhibited by CTN repeated applications. After 28 days of incubation, bacterial 16S rRNA gene abundances in T1 and T5 treatments were significantly lower than those in the CK treatments (46.4 and 36.6 % of the CK treatment in acidic red soil, 53.6 and 37.9 % of the CK treatment in paddy soil). Archaeal 16S rRNA gene abundances of T1 and T5 treatments were observed the similar trends (56.1 and 40.8 % of the CK treatment in acidic red soil, 45.6 and 43.7 % of the CK treatment in paddy soil). Repeated applications at 25 mg kg^?1 exerted significantly negative effects on the Shannon-Weaver, Simpson and McIntosh indices.

Conclusions

Microbial activity, biomass, and functional diversity were significantly inhibited by repeated CTN application at the higher dosage (25 mg kg^?1), but the inhibitory effects by the application at the recommended dosage (5 mg kg^?1) were erratic. More emphasis needs to be placed on the soil type and cumulative toxicity from repeated CTN application when assessing environmental risk.

     

Effects of nitrification inhibitor 3,4-dimethylpyrazole phosphate and fungicide iprodione on soil fungal biomass and community: based on internal transcribed spacer region

Purpose

Nitrification inhibitors that impact soil nitrifying microorganisms have been widely applied in agricultural soils to enhance the efficiency of nitrogen fertilizers. However, little is known about their combined impact with other chemical applications, such as fungicides, on soil fungi. This study specifically examined the effects of the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP), alone or together with the fungicide iprodione, on fungi biomass and community in a typical farmland soil.

Materials and methods

Four treatments were set: (1) control of zero agrochemical applications (CK), (2) a single DMPP application (DAA), (3) repeated iprodione applications (4×IPR), and (4) combined applications of DMPP and iprodione (DAA+4×IPR). The agrochemicals were applied at the recommended intervals, and the soil samples were incubated in the dark for 28 days. During the incubation, soil sample DNA was extracted, and the effects of DMPP and iprodione applications on soil fungal internal transcribed spacer (ITS) abundances were determined with quantitative PCR (qPCR). At the end of the incubation, Illumina MiSeq method was employed to assess soil fungal community diversity and structure.

Results and discussion

DMPP application had a negligible effect on fungal ITS abundance. However, repeated iprodione applications significantly decreased fungal ITS abundances. After 28 days of incubation, the fungal ITS abundances in the 4×IPR and DAA+4×IPR treatments were 43.6 and 56.2% of that measured from the CK treatment, respectively. Shannon indices of fungal communities demonstrated the treatment-induced gradients, with the DAA+4×IPR treatment harboring the highest Shannon index. Fungal community structures following the DAA and 4×IPR treatments remained overlapping with that in the CK treatment, but repeated iprodione applications markedly enriched the family Teratosphaeriaceae. Relative to the CK treatment, fungal community structure in the DAA+4×IPR treatment was significantly changed, with the families Cephalothecaceae, Hypocreaceae, and Cordycipitaceae harboring a linear discriminant analysis value >3.

Conclusions

DMPP application had negligible effects on soil fungal biomass, community diversity, and structure, potentially indicating that the DMPP is “bio-safe.” Conversely, repeated iprodione applications significantly decreased fungal ITS abundances. Moreover, the family Teratosphaeriaceae could be further investigated as a potential biomarker of the impacts of iprodione on soil fungi. The combined applications of DMPP and iprodione stimulated the Shannon diversity index and markedly changed soil fungal community structure.

     

Assessing the potential of using biochar in mine rehabilitation under elevated atmospheric CO<Subscript>2</Subscript> concentration

Purpose

Re-establishment of soil nitrogen (N) capital is a priority in mine rehabilitation. We aimed to evaluate the effects of biochar addition on improving mine spoil N pools and the influence of elevated CO₂ concentration on mine rehabilitation.

Materials and methods

We assessed the effects of pinewood biochar, produced at three temperatures (650, 750 and 850 °C, referred as B₆₅₀, B₇₅₀ and B₈₅₀, respectively), on mine spoil total N concentrations with five different plant species, including a tree species (Eucalyptus crebra), N-fixing shrubs (Acacia floribunda and Allocasuarina littoralis) and C₃ and C₄ grasses (Austrodanthonia tenuior and Themeda australis) incubated at ambient (400 μL L^?1) and elevated (700 μL L^?1) atmospheric CO₂ concentrations, as well as the effects of elevated CO₂ on mine rehabilitation.

Results and discussion

Soil total N significantly improved following biochar incorporation under all plant species (P < 0.05) except for T. Australis. E. crebra had the highest soil total N (0.197%, 0.198% and 0.212% for B₆₅₀, B₇₅₀ and B₈₅₀, respectively). Different from the negligible influence of elevated CO₂ on soil properties under the grasses and the N-fixing shrubs, elevated CO₂ significantly increased soil water and hot water extractable organic C (WEOC and HWEOC, respectively) and decreased total C under E. crebra, indicating that the nutrient demands were not met.

Conclusions

Biochar addition showed the potential in mine rehabilitation in terms of improving soil N pool, especially with E. crebra. However, it would be more difficulty to rehabilitate mine spoils in future with the rising atmospheric CO₂ concentration.

     

浓度直读法快速测定饲料中的氯化物

为建立一种饲料中氯化物测定的新方法,选用鸡饲料、猪饲料研磨,过筛,超声波浸提后,用浓度直读法测定。结果表明:样品为5.0000 g,柠檬酸钠为0.20 g/L、pH 6.00、硝酸钾为1.40 mol/L时,加标回收率大于98.3%,氯离子检出限为0.0131 mmol/L,相对标准偏差小于3.4%(n=5)。与国家标准对照测定,经显著性检验表明,两种方法之间不存在显著性差异。浓度直读法不需要大型仪器和繁琐操作步骤,具有携带便利、成本低廉、快速简便、读数直观的优点。为饲料中氯化物的测定提供了一种新型快速分析技术,有较好的推广应用前景。     

Phyllostachys edulis (moso bamboo) rhizosphere increasing soil microbial activity rather than biomass

Purpose

Rhizosphere and fertilization might affect soil microbial activities, biomass, and community. This study aimed to evaluate the impacts of Phyllostachys edulis (moso bamboo) rhizospheres on soil nutrient contents and microbial properties in a moso bamboo forest with different fertilizer applications and to link soil microbial activities with abiotic and biotic factors.

Materials and methods

The experiment included three treatments: (1) application of 45% slag fertilizer (45%-SF); (2) application of special compound fertilizer for bamboos (SCF); and (3) the control without any fertilizer application (CK). Simultaneously, bulk soils and 0.5, 2.5, 4.5, and 6.5-year-old (y) bamboo rhizosphere soils were selected. Soil nutrient contents were analyzed. Microbial activities were evaluated based on the activities of soil enzymes including β-glucosidase, urease, protease, phosphatase, and catalase. The total microbial biomass and community were assessed with the phospholipid fatty acids (PLFAs) method.

Results and discussion

In the CK and SCF treatments, organic matter contents of rhizosphere soils were significantly higher than those of bulk soils. Soil β-glucosidase, urease, protease, phosphatase, and catalase activities in rhizosphere soils were higher than those of bulk soils, with the sole exception of β-glucosidase of 0.5 y rhizosphere soil in the 45%-SF treatment. Compared with the CK treatment, fertilizer applications tended to increase soil total PLFAs contents and changed soil microbial community. Moso bamboo rhizospheres did not significantly increase the total microbial biomass. In the SCF treatment, the Shannon index of bulk soil was significantly lower than those of rhizosphere soils.

Conclusions

Our results suggested that both rhizospheres and fertilizer applications could change the soil microbial community structures and that moso bamboo rhizosphere could increase microbial activity rather than biomass in the forest soils with different fertilizer applications.

     

Effect of Silicon on Growth, Physiology, and Cadmium Translocation of Tobacco (Nicotiana tabacum L.) in Cadmium-Contaminated Soil

Silicon(Si) offers beneficial effect on plants under cadmium(Cd) stress such as promoting plant growth and increasing resistance to heavy metal toxicity. In this study, a pot experiment was performed to study the role of Si in alleviating Cd toxicity in tobacco(Nicotiana tabacum L.) plants on a yellow soil taken from Guiyang, China. Nine treatments consisting of three concentrations of Cd(0, 1, and 5 mg kg~(-1)) together with three Si levels(0, 1, and 4 g kg~(-1)) were established. Plant growth parameters, Cd concentration,and the malondialdehyde(MDA), chlorophyll, and carotenoid contents were determined 100 d after transplanting of tobacco seedlings.Application of exogenous Si enhanced the growth of tobacco plants under Cd stress. When 5 mg kg~(-1) Cd was added, Si addition at 1 and 4 g kg~(-1) increased root, stem, and leaf biomass by 26.1%–43.3%, 33.7%–43.8%, and 50.8%–69.9%, respectively, compared to Si addition at 0 g kg~(-1). With Si application, the transfer factor of Cd in tobacco from root to shoot under both 1 and 5 mg kg~(-1) Cd treatments decreased by 21%. The MDA contents in the Si-treated tobacco plants declined by 5.5%–17.1% compared to those in the non-Si-treated plants, indicating a higher Cd tolerance. Silicon application also increased the chlorophyll and carotenoid contents by 33.9%–41% and 25.8%–47.3% compared to the Cd only treatments. Therefore, it could be concluded that Si application can alleviate Cd toxicity to tobacco by decreasing Cd partitioning in the shoots and MDA levels and by increasing chlorophyll and carotenoid contents, thereby contributing to lowering the potential health risks of Cd contamination.     

3种诱抗剂对凤丹抗病害的诱导效果

分别用5个浓度的3种诱抗剂(Harpin、BTH和SA)喷施凤丹叶面,并以清水处理为对照,统计叶片病斑面积和病叶数,从而测定诱抗剂对凤丹抗3种主要病害(红斑病、灰霉病和黑斑病)的诱导效果;同时,测定了最适浓度诱抗剂对3种病原菌的抑制活性,以及对凤丹植株生理指标的影响.结果表明:3种诱抗剂均可有效地诱导凤丹对不同病害产生抗性,其中,BTH的诱抗效果最佳;3种诱抗剂对凤丹抗主要病害的诱导效果均表现为红斑病黑斑病灰霉病;诱抗剂处理显著提高了凤丹植株可溶性蛋白和色素含量及相关酶活性,显著降低了超氧阴离子自由基和丙二醛的含量;诱抗剂对凤丹3种病害的病原菌无毒杀作用,但可诱导植株获得系统抗性.