中国滨海湿地碳储量估算

滨海湿地生态系统碳汇功能强大,探究其固碳能力对于降低温室气体浓度,缓解全球气候变暖具有重要意义。基于谷歌地球引擎（Google Earth Engine, GEE）提供的1987—2020年Landsat遥感数据及已发表的滨海湿地碳密度数据,使用遥感定量反演与生命地带法相结合的方法,研究中国滨海湿地30多年来碳储量时空变化,结果表明：（1）盐沼湿地主要分布于沿海北部区域,光滩主要分布于沿海东部区域,红树林湿地主要分布于沿海南部区域;（2）中国南部滨海湿地碳密度明显高于北部和东部滨海湿地;（3）中国滨海湿地总碳储量整体呈降低趋势,沿海北部区域与东部区域总碳储量大于南部区域。气候、植被与土地利用变化共同影响了滨海湿地碳储量的时空动态,以围填海为主的人类活动是影响滨海湿地碳储量变化的主要因素。研究结果可为有效评估滨海湿地的碳汇能力,制定减排增汇措施,应对气候变化提供理论依据,也可为我国滨海湿地生态系统管理和退化湿地生态恢复提供决策支持。     

Impact of manure application on forms and quantities of phosphorus in a Chinese Cambisol under different land use

Purpose

It is critical to understand the effect of manure application on the availability of phosphorus (P) and the potential environmental contamination by runoff and leaching. However, previous studies generally focused on cultivated soil layer in single cropping systems. The aim of this study was to evaluate the effect of manure application on soil P forms and quantities to the 200 cm depth in a Chinese alkaline Cambisol in different cropping systems and the potential environmental implications.

Materials and methods

The sampling site, Shunyi District, is located in the peri-urban area of Beijing in the North China Plain, where large quantities of manure generated from intensive animal operations have been applied to agricultural fields. A field survey was carried out before sampling to identify soil sampling sites with long-term manure application and an adjacent area receiving no manure used for the same crop production. Soil samples from three cropping systems (vegetables, cereals, and trees) were vertically collected to a depth of 200 cm with the following depth increments: 0–20, 20–60, 60–90, 90–120, 120–160 and 160–200 cm. Soil samples were analyzed for plant-available P (Olsen P) and various P fractions by sequential P fractionation. Degree of P saturation (DPS) was also determined.

Results and discussion

Soil calcium bound P was the most abundant P fraction, followed by the residual P. Organic P only accounted for less than 5 % of total P in most of the soils. Manure application increased the levels of inorganic P (Pi), with higher proportions of Pi in labile forms than stable forms. After manure application for 8–15 year, available P (Olsen P) and DPS values of the 0–20 cm layer in all sites exceeded the threshold for Olsen P (60 mg?kg^?1) and DPS (30 %) and the risk of P loss by runoff is expected to significantly increase. The DPS values were generally lower than 30 % below 20 cm, indicating a minimal risk of P loss via leaching from deeper soil.

Conclusions

The results indicated that in typical peri-urban areas of the North China Plain, the on-going practice of manure application not only increased the size of each of the labile and non-labile P pools, but also caused a shift in the relative sizes of the different pools, regardless of the cropping systems. However, contrary to what was expected, soil P loss through surface runoff would be a greater concern than leaching following long-term manure amendment.     

Effects of rainfall and manure application on phosphorus leaching in field lysimeters during fallow season

Purpose

Transformation and transport of soil phosphorus (P) from chemical fertilizer or manure are affected by agronomic practices (i.e., fertilization, irrigation, and tillage) and numerous abiotic factors (i.e., temperature, drought, and rainfall). Previous studies on the effects of manure application on P loss were mostly conducted during cultivation and often using the laboratory column approach. Validated field observations by integrating P availability with the risk of P loss are few. This study aimed to evaluate the effects of rainfall and manure application on P leaching during fallow season.

Materials and methods

An in situ field lysimeter experiment was performed. Leachate was collected and analyzed for total P (TP) and dissolved reactive P (DRP). At the end of the lysimeter trial, soils were sampled incrementally to a depth of 40 cm with the following depth intervals: 0–4, 4–10, 10–20, 20–30, and 30–40 cm. Soil water extractable P (P_w) was analyzed and degree of P saturation (DPS) was calculated after oxalate and Mehlich-3 (M3) extractions.

Results and discussion

Phosphorus loading was found below 40 cm in all treatments and P was most concentrated in the 4–10 cm soil layer. High rainfall enhanced P leaching and consequently led to lower P_w and higher leachate DRP and TP than low rainfall. Furthermore, P leaching was observed regardless of manure application, with the highest leachate DRP (1.83 mg L^?1) and TP (7.46 mg L^?1) concentrations found at the end of experiment (day 53). Observed P leaching loads during fallow season (53 days) varied between 0.08 and 1.21 kg ha^?1. The thresholds of DPS indicating P leaching were identified at 18.9% DPS_M3(Ca) and 12.9% DPS_M3(Ca+Mg), respectively. In this study, the DPS_M3(Ca) and DPS_M3(Ca+Mg) values exceeded the corresponding thresholds in the upper 30-cm soil layer but did not reach the thresholds at 30–40 cm. Nevertheless, the leachate DRP and TP indicated soil P leaching.

Conclusions

The results showed that intensive rainfall could significantly increase P leaching from manure application. Moreover, P leaching could occur in fallow season even in the absence of manure input, which should be assessed by not only soil P sorption capacities, but also soil fertilization history and hydrologic conditions. Implementation of soil P level evaluation is critical before spreading manure on land to avoid P pollution. Cost-effective and applicable soil test methods are required to generate environmental indicators to classify agricultural lands for risk of P loss, providing basis to safe manure disposal.     

Spatiotemporal evolution and prediction of habitat quality in Hohhot City of China based on the InVEST and CA-Markov models

With the acceleration of urbanization, changes in the urban ecological environment and landscape pattern have led to a series of prominent ecological environmental problems. In order to better coordinate the balanced relationship between city and ecological environment, we selected land use change data to evaluate the habitat quality in Hohhot City of China, which is of great practical significance for regional urban and economic development. Thus, the integrated valuation of ecosystem services and tradeoffs (InVEST) and Cellular Automata-Markov (CA-Markov) models were used to analyze, predict, and explore the Spatiotemporal evolution path and characteristics of urban land use, and forecast the typical evolution pattern of land use in 2030. The results showed that the land use types in Hohhot City changed significantly from 2000 to 2020, and the biggest change took place in cultivated land, grassland, shrub, and artificial surface. The decrease of cultivated land area and the increase of artificial surface area were the main impact trend of land use change. The average value of habitat quality had been decreasing continuously from 2000 to 2020, and the values of habitat degradation were 0.2605, 0.2494, and 0.2934 in 2000, 2010, and 2020, respectively, showing a decreasing trend. The decrease of habitat quality was caused by the needs of economic development and urban construction, as well as the impact of land occupation. During this evolution, many cultivated land and urban grassland had been converted into construction land. The simulated land use changes in 2030 are basically the same as those during 2000-2020, and the habitat quality will still be declining. The regional changes are influenced by the urban rapid development and industrial layout. These results can provide decision-making reference for regional urban planning and management as well as habitat quality evaluation.     

杉木涩籽形成中类黄酮类代谢物的积累特征

[目的]比较杉木涩籽形成过程中类黄酮类代谢物的积累特征,为进一步揭示杉木涩籽形成机制提供参考.[方法]以涩籽率分别为24％和90％的杉木家系(L家系和H家系)种子为试材,分别于授粉后70、80、90、100、110 d取样.采用试剂盒、高效液相色谱、荧光定量PCR等方式测定并分析不同家系种子类黄酮生物合成途径关键代谢物...     

玉米杂交种丹科2118的选育与应用

丹科2118是丹东农业科学院以自选系CH36为母本，丹598为父本组配而成的中晚熟杂交种，经各地试验、试种结果表明：丹科2118比现成应用的中晚熟品种增产10％以上，并具有抗病、抗倒、适应性强、熟期适中、增产潜务大等特点，经推广试种，深受农民欢迎。     

采种甜菜原地保护越冬栽培技术

山东维坊市采种甜菜原地保护越冬栽培技术通常8月25日前后育苗,11月上、中旬盖膜,并在苗床北侧设立防风障,改善苗田小气候,于翌年2月中、下旬揭膜,定植时间可放宽到3月上旬至下旬,与窖藏春栽采种甜菜比,增产率可达25%以上,是一项值得推广的增产技术。     

镁对‘新天玲’西瓜叶片光合色素、可溶性蛋白含量和硝酸还原酶活性的影响

通过沙培试验,研究0(CK)、24、48、96、192 mg/L不同镁水平对‘新天玲’西瓜不同生育期叶片光合作用色素、可溶性蛋白含量和硝酸还原酶活性的影响。结果表明:镁水平影响‘新天玲’西瓜的整个生长发育过程,各时期随着镁水平的升高,西瓜叶片中叶绿素、类胡萝卜素、可溶性糖、可溶性蛋白含量和硝酸还原酶活性呈先升高后降低趋势,在镁水平为48 mg/L时各物质含量达到同期的最大值、NR活性最强,为最适镁浓度;而缺镁、低镁、镁过量均会产生不利影响;膨瓜期是‘新天玲’西瓜受镁水平影响比较严重的时期,该期应特别注意镁肥用量,以减轻镁对西瓜叶片碳氮代谢指标的影响,从而促进西瓜优质、高产。