Recruitment limitation in forests: Lessons from an unprecedented mountain pine beetle epidemic

Since the mid-1990s the forests of central British Columbia have undergone an unprecedented Mountain Pine Beetle (Dendroctonus ponderosae Hopkins) (MPB) epidemic that has resulted in extensive mortality of canopy lodgepole pine (Pinus contorta var. latifolia Engelm.). This study investigated how seed-source availability, seedbed substrate, overstory structure, and time since MPB attack interact to affect post-MPB seedling recruitment of the dominant tree species of these forests. In addition to post-MPB recruitment, these forests may be regenerated by trees established in the understory prior to MPB disturbance. Accordingly, we examined abundance and patterns of all regeneration less than 130 cm tall. We found post-MPB recruitment was sparse. Subalpine fir (Abies laciocarpa (Hook.) Nutt.) comprised the majority of the post-MPB recruitment. It increased with local parent tree basal area and increased strongly with proximity to a major seed source. This resulted in a patchy distribution for subalpine fir post-MPB regeneration. Lodgepole pine post-MPB recruitment was limited by overstory shading. Recruitment of pine decreased as the total overstory basal area increased. Interior spruce (Picea glauca × engelmannii) post-MPB recruitment was similarly limited by total overstory basal area. Seedbed substrates were uniform and dominated by moss. Substrate type distribution did not change as time since MPB disturbance increased. The overall low post-MPB recruitment observed was likely due to a lack of disturbance to the moss-dominated forest floor. Moss is known to be a poor substrate in northern forests. The distribution of all regeneration less than 130 cm tall showed the same trends as the post-MPB regeneration. We believe the post-MPB seedling recruitment dynamics of these forests was not substantially changed from conditions prior to MPB disturbance. There was no pulse of regeneration up to 10 years post-MPB disturbance. Unless this changes, future stand structure will be dominated by the seedling bank established prior to the MPB epidemic. Subalpine fir dominated the seedling bank (68%) and post-MPB recruitment (94%). This suggests that MPB-disturbed forests are undergoing a substantial shift in landscape-level species composition.     

生物活性炭技术在印染废水深度处理中的应用研究

[目的]研究生物活性炭技术深度处理印染废水。[方法]利用生物活性炭技术对印染行业生化出水进行深度处理,探讨了生物活性炭滤塔运行方式、进水浓度、滤速等因素对处理效果的影响。[结果]上向流、进水CODCr浓度低于300 mg/L、滤速1.88 m/h是生物活性炭滤塔处理印染行业生化出水的合适工艺参数,并得到滤塔的反冲洗周期约为60 h。[结论]生物活性炭技术深度处理印染废水可以达到中水回用的目的。     

《高等农业机械学》课程建设与改革初探

《高等农业机械学》是农业机械化工程专业硕士研究生的主干专业课。本文在对该课程已有的建设成果,以及课程在国内外现状分析的基础上,就教学内容、教学方法等方面提出了几点改革思路。     

Advanced glycation end products induce apoptosis of human ovarian granulosa COV434 cells and up-regulate pro-inflammatory cytokine HMGB1 autocrine

AIM:To study whether advanced glycation end products (AGEs) induce the apoptosis of human ovarian granulosa COV434 cells, and to explore the possible mechanism. METHODS:Human ovarian granulosa COV434 cells were treated with AGEs at different concentrations. Flow cytometry was used to observe the apoptotic rate. The protein levels of caspase-3 and cleaved caspase-3 were determined by Western blot. The release of high mobility group box 1 protein (HMGB1) in the culture supernatant was measured by ELISA. RESULTS:Compared with control group, early apoptotic rate and late apoptotic rate in 100 mg/L AGEs group and 200 mg/L AGEs group were significantly increased (P<0.05). No obvious difference of caspase-3 protein level in each group was observed, while the protein levels of cleaved caspase-3 in 100 mg/L AGEs group and 200 mg/L AGEs group were significantly increased compared with control group (P<0.05). In addition, compared with control group, pro-inflammatory factor HMGB1 in the culture medium in 100 mg/L AGEs group and 200 mg/L AGEs group was significantly increased. CONCLUSION:The apoptosis of human ovarian granulosa COV434 cells induced by AGEs may be related to pro-inflammatory reaction.     

家蚕晚期胚胎原代细胞分化和转分化的研究

对家蚕晚期胚胎组织进行原代培养,记录了培养过程中出现的多种分化和转分化现象。发现已分化的晚期胚胎组织、细胞尚可继续分化和转分化形成各种不同类型的组织与细胞,而且这些细胞多有一定的增殖能力,暗示了家蚕晚期胚胎组织可能有多种内部器官组织的多能干细胞存在。     

Estimating aboveground biomass in forest and oil palm plantation in Sabah, Malaysian Borneo using ALOS PALSAR data

Conversion of tropical forests to oil palm plantations in Malaysia and Indonesia has resulted in large-scale environmental degradation, loss of biodiversity and significant carbon emissions. For both countries to participate in the United Nation’s REDD (Reduced Emission from Deforestation and Degradation) mechanism, assessment of forest carbon stocks, including the estimated loss in carbon from conversion to plantation, is needed. In this study, we use a combination of field and remote sensing data to quantify both the magnitude and the geographical distribution of carbon stock in forests and timber plantations, in Sabah, Malaysia, which has been the site of significant expansion of oil palm cultivation over the last two decades. Forest structure data from 129 ha of research and inventory plots were used at different spatial scales to discriminate forest biomass across degradation levels. Field data was integrated with ALOS PALSAR (Advanced Land-Observing Satellite Phased Array L-band Synthetic Aperture Radar) imagery to both discriminate oil palm plantation from forest stands, with an accuracy of 97.0% (κ = 0.64) and predict AGB using regression analysis of HV-polarized PALSAR data (R² = 0.63, p < .001). Direct estimation of AGB from simple regression models was sensitive to both environmental conditions and forest structure. Precipitation effect on the backscatter data changed the HV prediction of AGB significantly (R² = 0.21, p < .001), and scattering from large leaves of mature palm trees significantly impeded the use of a single HV-based model for predicting AGB in palm oil plantations. Multi-temporal SAR data and algorithms based on forest types are suggested to improve the ability of a sensor similar to ALOS PALSAR for accurately mapping and monitoring forest biomass, now that the ALOS PALSAR sensor is no longer operational.     

Advanced glycosylation end products promote migration of podocytes through mTORC1/uPAR pathway

AIM: To investigate the influence of advanced glycosylation end products-modified bovine serum albumin (AGE-BSA) on mammalian target of rapamycin complex 1 (mTORC1), urokinase-type plasminogen activator receptor (uPAR), and cell mobility in the podocytes, and to further explore the probable relationship. METHODS: The conditionally immortalized mouse podocyte cell line was cultured in vitro. MTT assay and immunofluorescence were used to analyze the cell viability and cytoskeleton of the podocytes treated with the stimuli and intervention agents. The activity of mTORC1 and the expression level of uPAR in normal podocytes and podocytes treated with control BSA or AGE-BSA were detected by Western blotting. The migration ability of the podocytes was determined by would-healing assay. Rapamycin was added to inhibit the activity of mTORC1 along with the addition of AGE-BSA to observe the changes of uPAR and the motility of podocytes. RESULTS: No significant difference of the cell viability or cytoskeleton in the podocytes treated with the stimuli and intervention agents was observed. AGE-BSA up-regulated the activity of mTORC1 and the expression of uPAR, and induced the high mobility of the podocytes. Rapamycin obviously reduced the high expression level of uPAR and the increase in the migration ability of podocytes caused by AGE-BSA treatment. CONCLUSION: AGE-BSA might cause the high migration of podocytes through the mTORC1/uPAR signaling pathway.     

基于AMSR-E与MODIS数据海表面温度遥感反演研究

海洋表面温度是海洋环境的重要参数。遥感技术是进行海表面温度研究的有效手段之一。以印度洋北部海域为研究区域,利用Aqua卫星上的微波数据（AMSR-E）和光学数据（MODIS）,进行了海表温度反演研究。首先对AMSR-E L2A数据和MODIS-L1B数据进行预处理,然后将AMSR E的各极化通道亮温数据与实测海表温度进行相关性分析,通过多元线性回归建立AMSR-E海表温度的反演模型,而MODIS海表温度则通过采用线性多通道算法得到,最后以AMSR-E亮温数据为主,MODIS海表温度数据为辅,采用多元线性回归的方法建立了海表温度反演模型。利用该模型反演印度洋北部海域海表温度,反演结果与实测数据相比,其均方根误差为0.323 97 ℃。