南疆植被总初级生产力对区域降水的响应规律

为研究总初级生产力(Gross primary productivity,GPP)对区域降水的响应规律,本研究通过对南疆地区喀什、阿克苏、和田3个市2000—2014年的GPP进行分析,得出GPP的时空分布规律,进而与2000—2011年同期的降水进行耦合分析,以探寻植被GPP与降水之间的响应关系,从而为南疆地区植被生态保持和可持续发展提供依据。结果表明:1)从时间尺度来看,GPP呈现出与季节相关的波动性,年均GPP的极值点基本出现在每年的7月;2)在空间分布上,和田地区的GPP在空间上呈现北低南高的空间格局,阿克苏地区的GPP呈现北高南低的空间格局,并且在数值上存在较大的差异性,喀什地区的GPP呈现北高南低的空间格局,西北部GPP分布比较集中并有较高的值;3)变化趋势上,和田地区呈现上升趋势、阿克苏地区整体比较稳定、喀什地区呈现上升的趋势;4)研究区域内GPP与降水之间均为正相关关系。当降水滞后1个月时,和田及喀什GPP与降水之间的相关系数显著提高,但是阿克苏地区没有表现出时滞性,说明响应关系更加明显。     

内蒙古苏木山华北落叶松生物量及碳储量研究

森林生物量、碳储量是评价森林生长状况的重要指标。通过野外样地调查及室内烘干称重等方法,研究了苏木山林场不同林龄华北落叶松人工林乔木层、灌木层、草本层生物量以及乔木层净生产力、碳储量积累特点和变化趋势。结果表明:幼龄林、中龄林、近熟林平均木的生物量分别为26.41 kg、32.70 kg、107.81 kg;林分生物量分别为43.66 t·hm^-2、79.88 t·hm^-2、125.83 t·hm^-2;灌木层和草本层生物量之和分别为1.44 t·hm^-2、1.19 t·hm^-2、0.95 t·hm^-2;乔木层净第一生产力分别为2.56 t·hm^-2·a^-1、3.07 t·hm^-2·a^-1、3.40 t·hm^-2·a^-1,碳储量分别为22.20 t·hm^-2、40.55 t·hm^-2、63.80 t·hm^-2。苏木山华北落叶松人工林生物量、碳储量随林龄增加而增大,各器官碳储量从大到小依次为干>根>枝>皮>叶。     

水稻对硅元素吸收特性研究

[目的]研究水稻对硅元素的吸收特性。[方法]以水稻为材料,采用水培试验,设置0.085、0.850 mmol/L 2个硅水平,明确水稻对硅的吸收模式。[结果]在2个硅处理下水稻在12 h的总吸硅量明显高于蒸腾吸硅量,二者都随着时间的延长逐渐升高,并且蒸腾吸硅量占总吸硅量的比值表现为高硅浓度处理高于低硅浓度处理;2个处理在6 h内的硅吸收都受到了代谢抑制剂和低温的抑制,并且表现为高硅浓度的抑制程度低于低硅浓度的抑制程度;2个处理在12 h内木质部汁液硅浓度随时间的延长逐步升高,而外部溶液硅浓度随时间的延长逐步降低,并且木质部汁液硅浓度比外部溶液的硅浓度高数倍。[结论]水稻对硅的吸收存在主动吸收和被动吸收2个过程,尤其在高硅浓度处理下,被动吸收更不能忽视。     

珠三角河网初级生产力时空差异及其影响因素

为评价珠三角河网初级生产力,于2015年3月、6月、9月、12月对其进行取样调查,采用多元统计方法研究初级生产力时空差异及其与环境因素关系。结果表明,珠三角河网初级生产力(碳,C)为98.81~927.21mg·(m~2·d)~(-1),均值为346.51 mg·(m~2·d)~(-1)。调查区域初级生产力季节变化明显,总体上表现为春季冬季夏季秋季。各站位初级生产力均值以珠江桥站位最高[600.61 mg·(m~2·d)~(-1)],市桥站位最低[232.60 mg·(m~2·d)~(-1)]。初级生产力与透明度、氮磷营养盐、叶绿素a呈正相关关系(P0.01,n=52),与硅酸盐呈负相关关系(P0.01,n=52),与水体富营养化综合指数(EI)呈线性相关关系。珠三角河网以中营养、富营养为主体,与其他水域相比,初级生产力较低,污染程度较严重,需防止其向富养化发展。     

铲头堆砂白蚁原始繁殖蚁形成的周期

铲头堆砂白蚁Cryptotermes declivis Tsai et Chen是破坏木材及木制品的重要干木白蚁,其有翅成虫通过分飞配对后建立新群体,是其重要繁殖扩散途径。本文对铲头堆砂白蚁原始繁殖蚁形成周期进行了研究。以似桂木Paratocarpus sp.、团花Anthocephalus chinensis(Lam.) Rich. et Walp.和球花豆Parkia sp.作为该种白蚁食料,研究其原始繁殖蚁配对后从新建群体的形成到产生下一代的原始繁殖蚁,完成1个世代生活周期。结果表明,铲头堆砂白蚁在室温下,新建群体的形成、发展、发育至下一代原始繁殖蚁形成的周期约5 a,不同寄主材料对铲头堆砂白蚁生活周期没有显著性影响,但与群体数量多少显著相关。本研究首次明确了铲头堆砂白蚁群体发育成熟的周期,对该害虫的检疫与防控研究具有重要参考价值。     

白三叶与不同禾草混播群落17年稳定性经较研究

在适度放牧条件下开展了白三叶与多年生黑麦草、紫羊茅、草地早熟禾和无芒雀麦的两两豆禾混播群落的种间相容性、群落生产力和稳定性的研究。17年的研究结果表明,白三叶 紫羊茅组合的年均干物质产量502g/m2,显著高于其他组合(P<0.05),但前期以白三叶 多年生黑麦草最高(P<0.05)。在时间序列混播比例的变化上,白三叶逐渐增加,然后维持在一定的范围;多年生黑麦草第1年最高,后逐渐下降;紫羊茅和草地早熟禾变化不大,而无芒雀麦减少最快,并最终消失;白三叶 紫羊茅组合的比例动态变化最小,组分稳定,而且群落抵抗力最强,年均杂草侵入量仅为2.4 g/m2,极显著地低于其他处理(P<0.01)。参试禾本科牧草与白三叶的种间相容性为紫羊茅>多年生黑麦草≥草地早熟禾>无芒雀麦。种间相容性是混播群落长期稳定性的重要决定因素。时间梯度上的群落生产力变化趋势,白三叶 紫羊茅和白三叶 草地早熟禾呈平稳略升,而白三叶 多年生黑麦草和白三叶 无芒雀麦呈前高后低模式。对混播群落稳定性的判断存在时间尺度和空间尺度。     

Protective effect of butylated hydroxylanisole against hydrogen peroxide-induced apoptosis in primary cultured mouse hepatocytes

Butylated hydroxyanisole (BHA) is a synthetic phenolic compound consisting of a mixture of two isomeric organic compounds: 2-tert-butyl-4-hydroxyanisole and 3-tert-butyl-4-hydroxyanisole. We examined the effect of BHA against hydrogen peroxide (H₂O₂)-induced apoptosis in primary cultured mouse hepatocytes. Cell viability was significantly decreased by H₂O₂ in a dose-dependent manner. Additionally, H₂O₂ treatment increased Bax, decreased Bcl-2, and promoted PARP-1 cleavage in a dose-dependent manner. Pretreatment with BHA before exposure to H₂O₂ significantly attenuated the H₂O₂-induced decrease of cell viability. H₂O₂ exposure resulted in an increase of intracellular reactive oxygen species (ROS) generation that was significantly inhibited by pretreatment with BHA or N-acetyl-cysteine (NAC, an ROS scavenger). H₂O₂-induced decrease of cell viability was also attenuated by pretreatment with BHA and NAC. Furthermore, H₂O₂-induced increase of Bax, decrease of Bcl-2, and PARP-1 cleavage was also inhibited by BHA. Taken together, results of this investigation demonstrated that BHA protects primary cultured mouse hepatocytes against H₂O₂-induced apoptosis by inhibiting ROS generation.     

Evaluation of embryonic age and the effects of different proteases on the isolation and primary culture of chicken intestinal epithelial cells in vitro

The present study evaluates the effects of embryonic age and proteolytic enzymes on the isolation and primary culture of chicken enterocyte and to establish an effective technique for chicken intestinal epithelial cell (IEC) cultivation. Fourteen‐day‐old, 16‐day‐old and 18‐day‐old embryos (average weight: 52.23 ± 0.76 g, 50.86 ± 0.99 g, 48.98 ± 1.03 g) were the source for preparation of enterocyte culture, and trypsin‐ethylene diamine tetraacetic acid, collagenase, thermolysin and combination of collagenase and thermolysin were used for digestion medium. Optimal culture protocols were determined by qualitative assays of proliferation. Cells isolated by using 14‐day‐old embryo and collagenase obtain the best attachment and growth in culture, and the production of continuously growing IEC cultures. Thus, we conclude that the use of collagenase as a dissociating enzyme and 14‐day‐old embryo as a source can be advantageously applied to the isolation of chicken IEC and this method may be useful for various applications and basic studies of the intestinal tract concerning such objects as physiology, immunology and toxicology.     

Responses in gross primary production of Stipa krylovii and Allium polyrhizum to a temporal rainfall in a temperate grassland of Inner Mongolia,China

In the arid and semi-arid areas of China, rainfall and drought affect the growth and photosynthetic activities of plants. Gross primary productivity (GPP) is one of the most important indices that measure the photosynthetic ability of plants. This paper focused on the GPP of two representative grassland species (Stipa krylovii Roshev. and Allium polyrhizum Turcz. ex Regel) to demonstrate the effect of a temporal rainfall on the two species. Our research was conducted in a temperate grassland in New Barag Right Banner, Hulun Buir City, Inner Mongolia Autonomous Region of China, in a dry year 2015. We measured net ecosystem productivity (NEP) and ecosystem respiration flux (ER) using a transparent chamber system and monitored the photosynthetically active radiation (PAR), air and soil temperature and humidity simultaneously. Based on the measured values of NEP and ER, we calculated the GPP of the two species before and after the rainfall. The saturated GPP per aboveground biomass (GPP_AGB) of A. polyrhizum remarkably increased from 0.033 (±0.018) to 0.185 (±0.055) μmol CO₂/(gdw?s) by 5.6-fold and that of S. krylovii decreased from 0.068 (±0.021) to 0.034 (±0.011) μmol CO₂/(gdw?s) by 0.5-fold on the 1^st and 2^nd d after a 9.1 mm rainfall event compared to the values before the rainfall at low temperatures below 35°C. However, on the 1^st and 2^nd d after the rainfall, both of the saturated GPP_AGB values of S. krylovii and A. polyrhizum were significantly lower at high temperatures above 35°C (0.018 (±0.007) and 0.110 (±0.061) μmol CO₂/(gdw?s), respectively) than at low temperatures below 35°C (0.034 (±0.011) and 0.185 (±0.055) μmol CO₂/(gdw?s), respectively). The results showed that the GPP responses to the temporal rainfall differed between S. krylovii and A. polyrhizum and strongly negative influenced by temperature. The temporal rainfall seems to be more effective on the GPP of A. polyrhizum than S. krylovii. These differences might be related to the different physiological and structural features, the coexistence of the species and their species-specific survival strategies.     

Habitat configuration for an obligate shallow‐water delphinid: The Indo‐Pacific humpback dolphin,Sousa chinensis,in the Beibu Gulf (Gulf of Tonkin)

1. Habitat configuration is an important baseline to delineate protected area design, refine impact mitigation measures and define habitat protection plans for threatened species. For coastal delphinids, outlining their habitat configuration becomes a real challenge when faced with large distribution ranges that straddle international borders, leaving broad information gaps in uninvestigated areas.
2. This study projected likely habitats of Indo‐Pacific humpback dolphins, Sousa chinensis, in the Beibu Gulf (Gulf of Tonkin) based on occurrence data and remotely sensed oceanographic characteristics. Net primary productivity was derived to measure the ecosystem service of humpback dolphin habitats.
3. Bathymetry and chlorophyll‐a concentration are major variables contributing to humpback dolphin habitat configuration, which is characterized by shallow water depth and high primary productivity. Three major, likely habitats were identified in the northern Beibu Gulf from western Leizhou Peninsula to the China–Vietnam border, western Gulf of Tonkin from the Red River estuary to the central coast of Vietnam, and south‐western Hainan Island. Less than 9% of likely habitats are currently protected by marine protected areas.
4. Affinity to high primary productivity and shallow depths implies that prey abundance and foraging efficiency influence habitat selection by Indo‐Pacific humpback dolphins. Anthropogenic activities potentially altering oceanographic characteristics may impact regional marine ecosystem functions, and hence habitat configuration.
5. Habitat protection actions for Indo‐Pacific humpback dolphins include implementing coordinated and systematic surveys in major habitats, associating core habitat protection with protected area networks and maritime function zoning, ensuring ecosystem function integrity within major habitats, and reducing both explicit lethal impacts and implicit anthropogenic impacts from activities that change oceanographic features. The habitat protection plan should not only consider marine habitats, but also adjacent coastal landscapes and river catchments. This requires coordination, collaboration and information sharing between scientific research teams, government policy representatives, non‐governmental organizations, local communities and other interested stakeholders.