Cyclocarya paliurus is a versatile tree species with immense potential for development, as it combines edible, medicinal, and ornamental functions. Low temperature is one of the important abiotic factors that affect plant survival and flourishing but their response mechanism to low temperature is not yet clear. In this study, we utilized annual shoots of four genotypes of C. paliurus, namely T2, W10, M31 and S12, as materials. The physiological responses of annual shoots of C. paliurus to low temperature stress were elaborated by determining and comparing indicators related to cold resistance, such as relative electric conductivity, semi-lethal low temperature, malondialdehyde, soluble sugar, soluble protein, proline, superoxide dismutase and peroxidase. The contents of malondialdehyde, proline, soluble protein and peroxidase activities were not only correlated with the treatment temperature but also related to the genotypes. Osmotic substance (soluble sugar, soluble protein and proline) contents and antioxidant enzyme activities (peroxidase and superoxide dismutase) of the four genotypes showed a trend of increasing and then decreasing with the five decreasing temperatures. Furthermore, a comprehensive evaluation of cold resistance was performed by using a combination of principal component analysis and membership function, with the cold resistance ranked as W10 > M31 > S12 > T2. Results from this study would provide some references for extending the plantation areas.
The content of PAHs in surface soils of northeastern China is high, which causes long-term soil pollution and potential harm to human health. Influenced by the temperature, the soil in the northeast region is characterized by a long-term freeze–thaw seasonal climate, which greatly affects the process of soil remediation work. Therefore, it is necessary to study the remediation strategies of PAHs in low-temperature soils. Our group discovered that the combination of cold-tolerant fungi and bacteria was effective in degrading soil PAHs. However, we are required to further explore the choice of immobilization vector. In this study, four different types of biochar (C300, C500, B300, B500) were prepared at 300 °C and 500 °C using corn cob and wheat straw of industrial and agricultural waste as precursors. We then used the cross-mixing of these four types of biochar as the carrier for Pseudomonas sp. S4 and Mortierella alpina J7, which are bacteria capable of degrading PAHs. We used the adsorption immobilization method to prepare the repair materials for PAHs degradation mixed bacteria. Through comparison, the low-temperature and high-temperature mixed biochar (C300 + B500) was selected as the carrier. The results showed that mixed biochar immobilized degrading bacteria are the most effective in degrading Phe and Pyr in soil and their degradation effect was related to the mixing ratio. After 30 days of remediation at 15 °C, the best remediation effect was add immobilized mixed fungicide agent, mix biochar 1:2 using 0.67
种植绿肥是培肥改良果园土壤、提高水果产量品质的有效措施.为筛选适宜江西红壤幼龄橘园种植的冬绿肥品种,在橘园行间播种毛叶苕子(Viciavillosa Roth)、肥田萝卜(Raphanus sativus)、黑麦草(Lolium perenne)、鼠茅草(Vulpia myuros)等4种冬绿肥,研究种植不同冬绿肥对土壤化学性质、微生物量碳、氮和酶活性的影响.结果表明,与自然生草相比,短期种植冬绿肥对土壤pH、有机质和全氮的影响较小,对土壤速效养分有一定的提升效果,但均未发生显著变化.种植冬绿肥明显改善了土壤生化性质,使土壤 MBC 和 MBN 分别增加 47.9%-114%和 75.9%-292%,使 MBC/MBN 降低 14.2%-53.7%,其中鼠茅草和黑麦草处理效果最佳;种植冬绿肥还提高了土壤过氧化氢酶(1.70%-20.0%)、酸性磷酸酶(15.8%-78.9%)、脲酶(13.8%-46.6%)、转化酶(13.7%-55.5%)、过氧化物酶(120%-218%)、多酚氧化酶(4.70%-55.2%)等6种酶的活性,仍以鼠茅草和黑麦草的效果最佳.运用主成分分析对各处理的土壤生化性质进行综合评价,其得分排序为:鼠茅草(1.07)＞黑麦草(0.93)＞毛叶苕子(0.20)＞肥田萝卜(-0.24)＞自然生草(-2.31),进一步运用聚类分析可将其分为 3 类:鼠茅草和黑麦草(第Ⅰ类)、毛叶苕子和肥田萝卜(第Ⅱ类)、自然生草(第Ⅲ类).综上,种植冬绿肥可明显改善红壤幼龄橘园的土壤肥力状况,对土壤微生物量碳、氮含量和酶活性等生化性质的提升尤为明显,在实际生产中优先推荐鼠茅草、黑麦草作为冬绿肥品种.该研究为红壤区幼龄果园的土壤肥力培育、绿色生态种植提供了技术参考,有助于南方特色水果的量质协同提升和相关产业的健康可持续发展.
生态用地碳汇为从增汇角度实现"双碳"目标提供重要途径,综合分区优化对促进生态保护与经济高质量发展融合具有重要指导意义.在测算中国 31 省(市、区)各类生态用地碳汇总量及单位面积碳汇量的基础上,运用探索性空间数据分析、核密度估计,探究2000-2020年生态用地碳汇空间集聚特征和时空演进趋势,并基于碳汇与绿色GDP的脱钩关系和协调状态构建综合分区,结合重要生态功能区分布开展优化治理.研究表明,1)研究期内生态用地碳汇总量呈波动上升态势,年均增速为 0.077%;在空间上呈显著的集聚效应,湖南、贵州、广西属于高-高集聚区,形成高值辐射中心,山东属于低-低类型,为低值塌陷区.2)生态用地碳汇总量空间差异明显,高碳汇区碳汇能力强于其他地区;核密度估计显示高碳汇区和低碳汇区碳汇呈增加趋势,中碳汇区保持相对稳定,且三者均存在区内集聚特征.3)单位国土面积生态用地碳汇与单位生态用地面积碳汇均以高-高集聚类型和低-低集聚类型为主,呈现出较强的空间集聚特征,尤其南部地区的省(市、区)具有单位面积生态用地碳汇优势和潜力.4)生态用地碳汇与绿色GDP两者以脱钩和多元协调状态为主,大部分省(市、区)单位面积生态用地碳汇处于多元协调区,重要生态功能区的碳汇积极作用显现.研究结果为改善生态用地碳汇能力和潜力,推进生态领域实现"双碳"目标提供有益参考.
为揭示天山云杉森林的水源涵养功能,探究天山云杉林枯落物层和土壤层水文效应特征.以天山北麓中段的天山云杉森林为研究对象,沿海拔梯度(1500-2300 m)布设系列样地,采用样地调查法和室内浸泡法对天山云杉森林枯落物层和土壤层的水源涵养能力进行定量分析,明确其在海拔梯度上的分异特征.结果表明,1)天山云杉森林枯落物层厚度(2.50-3.38 cm)和蓄积量(13.6-21.7 t·hm-2),两者均随海拔的升高而显著减小(P＜0.05);天山云杉森林枯落物层最大持水量(50.9-65.0 t·hm-2)和有效拦蓄量(21.6-25.8 t·hm-2)均随海拔升高先增大后减小;对比不同海拔梯度枯落物的持水过程发现,其在浸水1h内持水量迅速增加,此时吸水速率最大;相同时间内,半分解层枯落物持水量均大于未分解层.2)在1500-1700、1700-1900、1900-2100、2100-2300 m 4个海拔段的土壤容重(0.481、0.621、0.643、0.452 g·cm-3)、毛管孔隙度(72.6%、77.5%、70.5%、75.8%)和总孔隙度(76.1%、81.0%、73.4%、78.8%)均表现为随海拔升高先增大后减小的趋势;各海拔梯度土壤饱和持水量与毛管持水量排序为1700-1900 m＞1500-1700 m＞2100-2300 m＞1900-2100 m,土壤有效持水量排序为:1700-1900 m＞1500-1700 m＞1900-2100 m＞2100-2300 m,均随海拔的升高表现为先增大后减小.3)枯落物层和土壤层总的有效持水量(83.4-95.9 t·hm-2)和总最大持水量(1390-1662 t·hm-2)均随海拔的升高先增大后减小,在各海拔段间无显著差异(P＞0.05).通过研究发现天山云杉森林生态系统的水源涵养能力总体呈现沿海拔梯度先增大后减小的趋势,中低海拔区域(1500-1900 m)水源涵养能力较好.
