青海省祁连圆柏天然林单木生物量模型构建

利用祁连圆柏整株生物量与生长指标数据，为估算祁连圆柏林的生物量估算提供参考。通过野外调查，共获取了63株祁连圆柏天然林样木生物量与生长指标实测数据。用其中50株样木数据进行回归模拟，用其余的13株样木数据对模型可靠性进行检验，构建器官生物量与生长指标间的回归模型。结果表明，祁连圆柏单木水平下，树干生物量模型的R²_adj为0.96，均方根、模型有效性和残差系数分别为0.50、0.85和0.05；枝条生物量模型的R²_adj为0.897，均方根、模型有效性和残差系数分别为0.69、0.80和-0.66；叶生物量模型的R²_adj为0.61，均方根、模型有效性和残差系数分别为0.54、0.86和0.15；根生物量模型的R²_adj为0.93，均方根、模型有效性和残差系数分别为0.12、0.997 和-0.01。在调查数据范围内构建的模型较好地反映了祁连圆柏生物量与生长指标间的关系，形式简单、使用方便；与实测值相比，树干与叶生物量模拟值偏小，枝和根偏大。     

Determination of critical nitrogen dilution curve based on leaf area index for winter wheat in the Guanzhong Plain,Northwest China

Excessive use of nitrogen(N) fertilizers in agricultural systems increases the cost of production and risk of environmental pollution. Therefore, determination of optimum N requirements for plant growth is necessary. Previous studies mostly established critical N dilution curves based on aboveground dry matter(DM) or leaf dry matter(LDM) and stem dry matter(SDM), to diagnose the N nutrition status of the whole plant. As these methods are time consuming, we investigated the more rapidly determined leaf area index(LAI) method to establish the critical nitrogen(N_c) dilution curve, and the curve was used to diagnose plant N status for winter wheat in Guanzhong Plain in Northwest China. Field experiments were conducted using four N fertilization levels(0, 105, 210 and 315 kg ha-1) applied to six wheat cultivars in the 2013–2014 and 2014–2015 growing seasons. LAI, DM, plant N concentration(PNC) and grain yield were determined. Data points from four cultivars were used for establishing the N_c curve and data points from the remaining two cultivars were used for validating the curve. The N_c dilution curve was validated for N-limiting and non-N-limiting growth conditions and there was good agreement between estimated and observed values. The N nutrition index(NNI) ranged from 0.41 to 1.25 and the accumulated plant N deficit(N_(and)) ranged from 60.38 to –17.92 kg ha~(-1) during the growing season. The relative grain yield was significantly affected by NNI and was adequately described with a parabolic function. The N_c curve based on LAI can be adopted as an alternative and more rapid approach to diagnose plant N status to support N fertilization decisions during the vegetative growth of winter wheat in Guanzhong Plain in Northwest China.     

Radioisotope and stable isotope ratios (Δ14C, δ15N) suggest larval lamprey growth is dependent on both fresh and aged organic matter in streams

Lampreys have a complex life cycle which includes a multi‐year infaunal larval stage (ammocoete). Gut content analysis has generally identified detritus (i.e., unidentifiable organic matter) as the major dietary component to ammocoetes, though algae can also be important. However, gut content preserves only a snapshot of the animal's diet and does not reflect assimilated material. In order to better characterise the nutritional sources supporting ammocoete growth, we analysed ammocoete body tissue and potential dietary sources at two streams using natural Δ¹⁴C and δ¹⁵N to estimate time‐integrated nutritional support. Bayesian isotope mixing models revealed differences in the importance of sources supporting ammocoetes between sites. Ammocoetes from a stream in a mixed land usage area (~50% agriculture, ~40% forest and ~10% developed) were primarily supported (mean: ~50%) by fresh terrestrial organic matter but were also supported by substantial contributions (mean: ~30%) by aged organic matter (AOM) and autochthonous material (algae; mean ~20%). In a predominantly forested (~90%) headwater stream, different modelling scenarios (uninformed or informed priors) suggested that algal support of ammocoete nutrition ranged from 7% to 45%. However, the model relying on informed priors developed from gut content analysis produced the low estimates, suggesting these were more reliable. When algae were a minor component of the nutrition at the forested site, ammocoetes were highly dependent on AOM (83 ± 26%; mean ± SD). Based on these findings, ammocoete growth and development are predicted to be strongly influenced by both land use and the availability of allochthonous and autochthonous materials of varying ages within streams.     

The economic benefits and costs of trees in urban forest stewardship: A systematic review

Understanding the benefits provided by urban trees is important to justify investment and improve stewardship. Many studies have attempted to quantify the benefits of trees in monetary terms, though fewer have quantified the associated costs of planting and maintaining them. This systematic review examines the methods used to jointly analyse the costs and benefits of trees in the urban landscape, assesses the relative balance of benefits and costs, and attempts to understand the wide variation in economic values assigned in different studies. The benefits most frequently studied are those related to environmental regulation and property values, and the available data show that these usually outweigh the costs. Aesthetic, amenity, and shading benefits have also been shown to provide significant economic benefits, while benefits in terms of water regulation, carbon reduction and air quality are usually more modest. Variation in benefits and costs among studies is attributed largely to differences in the species composition and age structure of urban tree populations, though methodological differences also play a role. Comparison between studies is made difficult owing to differences in spatiotemporal scope, and in the way urban forest composition and demographic structure were reported. The overwhelming majority of studies concern deciduous trees in Northern America, and much less is known about urban forests in other regions, especially in the tropics. Future work should thus seek to fill these knowledge gaps, and standardise research protocols across cities. In light of ambitious goals in many cities to increase tree cover, ongoing advances in valuation methods need to provide a more comprehensive accounting of benefits and costs, and to better integrate economic assessment into the decision-making process.     

Introduction to the International Symposium on Lipid Science and Health and research progress in lipid science and health

The International Symposium on Lipid Science and Health (ISLSH), which was organized annually by Oil Crops Research Institute of Chinese Academy of Agricultural Sciences (OCRI-CAAS) since 2016, has gained a strong reputation and attracted hundreds of delegates from around the world for discussion of lipid research trends and advances every year, to promote research and academic exchanges in the fields of lipid science and health. The 5th International Symposium on lipid Science and Health was successfully held in Wuhan, China, from October 23rd to 25th, 2020, to celebrate the 60th anniversary of OCRI-CAAS. The two-day symposium gathered well-known experts specialized in lipid science to share the current state of lipid research with emphasis on aspects covering: (1) lipid profiling and characterization, (2) lipid preparation and modification, (3) lipid improvement and regulation, and (4) lipid nutrition and health. The symposium was conducted by a combination of on-site and network meeting. More than 250 distinguished delegates from academia and industry participated in the on-site multidisciplinary meeting, and thousands of scholars attended the virtual event. This paper is as a record of the symposium proceedings and a brief summary of the advances and trends in 4 aspects of lipid science and health.     

铯－134在幼龄茶树叶片中的分布特点

茶树上喷洒￣（１３４）Ｃｓ后，老叶上的沉积量和新叶上的吸收量均按指数回归形式下降，下降的速率以老叶上最快，春茶叶和夏茶叶上次之，秋茶叶上最慢；灌溉和土壤中拌入￣（１３４）Ｃｓ后，茶叶对￣（１３４）Ｃｓ的吸收分两个阶段进行，前期随着时间延长而增加。后期则减少。吸收量有个最大值；茶叶中￣（１３４）Ｃｓ的含量在喷洒情况下比灌溉和拌土的高。     

Impact of postovulatory food deprivation on the ova transport, hormonal profiles and metabolic changes in sows.

The effect of food deprivation on ova transport, hormonal profiles and metabolic changes was studied in 20 crossbred multiparous sows during their second oestrus after weaning. To determine the time of ovulation, transrectal ultrasonographic examination was performed. The sows were divided into 2 groups, one control group (C-group), which was fed according to Swedish standards, and one experimental group (E-group). The E-group sows were deprived of food from the first morning meal after ovulation until slaughter. Blood samples were collected every second hour from about 12 h before expected ovulation in the second oestrus after weaning until slaughter and were analysed for progesterone, prostaglandin F2 alpha-metabolite, insulin, glucose, free fatty acids and triglycerides. All sows were slaughtered approximately 48 h after ovulation and the genital tract was recovered. The isthmic part of the oviduct was divided into 3 equally long segments and flushed separately with phosphate buffered saline (PBS). Uterine horns were also flushed with PBS. A significantly greater number of ova were found in the first and second part of the isthmus in the E-group (p = 0.05) while in the C-group most of the ova were found in the third part of the isthmus or the uterus (p = 0.01). The level of prostaglandin F2 alpha-metabolite was significantly higher in the E-group compared with the C-group. The concentration of progesterone increased in both groups after ovulation but there were no significant differences between the groups. The other blood parameters showed that the food-deprived sows were in a catabolic state. The 48 h period of fasting results, directly or indirectly in an delayed ova transport, which may be due to a delayed relaxation in the smooth circular muscle layer of the isthmus.     

阔叶树种的研究现状与江西研究的发展方向

通过对阔叶树种在我国及江西省的研究状况的论述，初步总结了阔叶树种的研究水平及研究方向，指出了江西省阔叶树种研究存在的问题，探讨了江西省今后阔叶树种研究的方向。     

中日森林文化比较研究及启示

日本是一个森林大国，拥有着丰富的森林资源和森林文化，其教训和经验对中国乃至全世界的后工业化国家都有着很大的启发和借鉴意义。对日本的森林状况进行回顾和评价，从其森林思想中汲取精华，不断挖掘森林文化所蕴藏的丰富含义，恢复和弘扬森林文化，这对中国正在开展的生态文明建设以及解决环境问题都能提供思考和帮助。     

奶牛繁殖疾病的调控

本文综述了奶牛繁殖疾病的发病原因和调控措施，分析认为奶牛的营养状况是影响奶牛繁殖力的重要因素。理想的奶牛管理应做到整个泌乳期始终监测奶牛的体况和奶牛日粮中微量元素的维生素的含量，避免营养素的不平衡而引发的奶牛繁殖障碍，同时应避免奶牛过肥或过瘦。适当补充某些维生素和矿物质十分重要。