Seasonality in the equatorial tropics: Flower,fruit, and leaf phenology of montane trees in the highlands of Southwest Uganda

Phenology influences many forest functions and can inform forest conservation and management, yet representative phenological data for most common tropical forest tree species remain sparse or absent. Between June 2011 and December 2013, we investigated flowering, fruiting, and leafing patterns in the Bwindi Impenetrable National Park, a montane forest located near the equator in Uganda, drawing on 16,410 observations of 530 trees of 54 species located between 2066 and 2527 m in elevation. The park's climate is equatorial with two wet and dry seasons each year. Flowering and fruiting were strongly seasonal while patterns in leafing were less pronounced. Flower occurrence peaked at the beginning of the short dry season followed by a pronounced trough during the beginning and the middle of the short wet season. Fruit occurrence had a pronounced peak during high rainfall months in March through April with most fruits ripening during drier months in May through July. Fruit scarcity was observed for a 4-month period spanning September to December and most flushing of leaves noted at the end of the wet season in November and December. Our binomial generalized linear mixed models indicated that flowering and fruiting were negatively associated with temperature and that leafing activity was positively associated with rainfall and temperature. These findings are consistent with the insolation- and water-limitation hypotheses suggesting that the seasonally varying availability of resources such as light, water, and nutrients determines these phenological patterns. Ideally, prolonged, multi-year community-level studies would be supported so as to better characterize the influence of climate and of climate variability.     

洗胃法在鳄蜥食性研究中的应用

为了研究洗胃法是否适用于鳄蜥（Shinisaurus crocodilurus）的食性研究,2006年8～9月我们在广东罗坑省级自然保护区,通过投喂食物,然后再冲洗的方法来检验洗胃法的冲洗效果。结果显示洗胃法对成体和亚成体鳄蜥的总洗出率均高于99．30％,食物个体数的洗出率均高于90．83％,投喂的12种食物都能被洗出。观察发现洗胃之后,对鳄蜥的正常生活没有影响。鳄蜥吃进的实验食物中,未洗出的食物大小与鳄蜥的体长、头宽、体重不相关;食物的洗出效率与鳄蜥的体长、头宽、体重不相关。成体、亚成体洗出和未洗出的食物大小均存在显著差异。未被洗出的食物个体在12种食物中不是随机分布的,体积大的食物比体积小的食物容易被洗出。研究表明,洗胃法适用于鳄蜥的食性研究,并且效果较好。     

Modeling and design of optimal flow perfusion bioreactors for tissue engineering applications

Perfusion bioreactors have been used in different tissue engineering applications because of their consistent distribution of nutrients and flow-induced shear stress within the tissue-engineering scaffold. A widely used configuration uses a scaffold with a circular cross-section enclosed within a cylindrical chamber and inlet and outlet pipes which are connected to the chamber on either side through which media is continuously circulated. However, fluid-flow experiments and simulations have shown that the majority of the flow perfuses through the center. This pattern creates stagnant zones in the peripheral regions as well as in those of high flow rate near the inlet and outlet. This non-uniformity of flow and shear stress, owing to a circular design, results in limited cell proliferation and differentiation in these areas. The focus of this communication is to design an optimized perfusion system using computational fluid dynamics as a mathematical tool to overcome the time-consuming trial and error experimental method. We compared the flow within a circular and a rectangular bioreactor system. Flow simulations within the rectangular bioreactor are shown to overcome the limitations in the circular design. This communication challenges the circular cross-section bioreactor configuration paradigm and provides proof of the advantages of the new design over the existing one.     

An examination of the relationship between sunlight exposure and hot flush in working women

ABSTRACT

We examined whether sunlight affects hot flushes in working menopausal women and explored effect modification by shift work and season. In this prospective cohort study, daily hot flush score (outcome) was measured by the 7-day North Central Cancer Treatment Group Daily Vasomotor Symptoms Diary. Daily duration of sunlight (≥2000 lux) was recorded by the HOBO MX2202 pendant. Both variables were measured in two 7-day data collection phases. T0 data were collected during the Australian Summer (December 2017, January and February 2018); and T1 data were collected in the Australian winter (June, July and August 2018). Linear mixed effects model was used. Shift work and season were both confounders and effect modifiers. To detect a median effect size of R² = 0.2, 34 women were required to achieve an effective sample size of 41. A total of 49 menopausal women were recruited, 11 shift and 38 day workers. Some 13 women had various missing observations. For shift workers, an hour increase in sunlight exposure was associated with a 1.4-point reduction in hot flush score (p = .016). This relationship was not significant for day workers (p = .185). The finding of this study suggests increased sunlight exposure might improve hot flushes in menopausal shift workers who are moderately bothered by hot flushes, but probably not in day workers. The possible role of shift-work associated circadian disruption on estrogen level in regard to elevated intensity and frequency of hot flush in menopausal women is discussed.     

Seasonal Dynamics of Plant Diversity on lnselbergs in the Ivory Coast (West Africa)

Inselbergs are isolated monolithic outcrops which are characterized by large areas of exposed crystalline rock. Due to harsh edaphic and microclimatic conditions, inselbergs are completely differentiated from their surroundings. Consequently they host a very distinct vegetation which is being investigated on a global scale over a six year period. The seasonal dynamics of Selected plant communities (Afrotrilepis pilosa mat, shallow depression, ephemeral flush vegetation) on granitic inselbergs in the Comoe National Park (NE Ivory Coast) were studied during the rainy period from May to November 1991 by recording all vascular plant species at 12 intervals. For the habitats investigated, the seasonal vegetation dynamics were related to the rainfall pattern. Maximum values both in species diversity and richness were attained in the first third of the rainy period. Drought in August and September caused a decline in species number and diversity in the shallow depression and ephemeral flush vegetation, resulting in mortality of more than 20% of the species. The individual communities studied differed considerably in species diversity and richness. We conclude that ephemeral flush and shallow depression communities are more species rich than the mat community which is dominated by the highly competitive and specialized K-strategist Afrotrilepis pilosa (a poikilohydric Cyperaceae) due to stochastic climatic perturbations which allow the maintenance of species rich non-equilibrium assemblages with r-strategists as major components.     

不同光脉冲方案对光下最大荧光参数及其计算参数的影响

光下最大荧光(F_m′)是植物生理生态研究中的重要参数,一般采用饱和脉冲(RF)方案来估计.然而,光系统Ⅱ(PSⅡ)受体库的反馈调节会影响RF方案对F_m′估计的准确性.为消除PSⅡ受体库反馈调节的影响,根据光脉冲强度(Q′)与叶绿素荧光(F′)的线性关系提出多相脉冲(MPF)方案,估算Q′无穷大时的F′(即F_m′).本研究采用MPF和RF方案分别对苦槠、青冈和乌桕3个树种叶片的叶绿素荧光和气体交换数据进行同步测量,并对两种方案估计的F_m′及其计算参数PSⅡ光化学效率(Φ_PSII)、PSⅡ的电子传递速率(J)、最大电子传递速率(J_max)、叶肉导度(g_m)和叶绿体内CO₂浓度(C_c)等光合参数进行比较,分析两种方案对3个树种叶片6个光合参数的影响.结果表明: 当光合有效辐射(PAR)<200 μmol·m^-2·s^-1时,两种方案对苦槠、青冈和乌桕叶片F_m′、Φ_PSII和J的估计无显著影响;当PAR>200 μmol·m^-2·s^-1时,采用MPF方案获得的苦槠、青冈和乌桕的F_m′分别比RF方案获得的F_m′高3.5%～5.2%、11.7%～18.0%和3.2%～7.1%;当PAR>200 μmol·m^-2·s^-1时,采用MPF方案获得的Φ_PSII、J和J_max分别不同程度地大于RF方案获得的参数,g_m和C_c分别不同程度地小于RF方案获得的参数.说明当PAR较低(<200μmol·m^-2·s^-1)时,MPF与RF方案对植物叶片F_m′、Φ_PSII、J的估计没有显著影响;当PAR较高(≥200μmol·m^-2·s^-1)时,MPF与RF方案对植物叶片F_m′、Φ_PSII、J、J_max、g_m和C_c的估计有显著影响,且RF方案对植物叶片的F_m′、Φ_PSII、J和J_max比MPF方案分别有不同程度的低估,对g_m和C_c则有不同程度的高估.     

黑河流域中游地区净初级生产力的人类占用

基于Miami模型,对黑河流域中游净初级生产力的人类占用（HANPP）及其与生态系统多样性的关系进行了研究,并对HANPP与生态足迹（EF）指标在可持续发展评估方面的价值进行了比较.结果表明：HANPP的提高将降低生态系统多样性,研究区现状年的平均HANPP率为38.61%,肃州区和甘州区的HANPP已超过生态系统潜在生产能力的极限;结合气候变化和社会经济发展状况进行分析,未来40年黑河流域中游生态系统将面临更大压力.与生态足迹（EF）相比,HANPP更适于从生态系统功能变化角度评估区域发展的可持续性.