基于耦合模型的干旱区植被净初级生产力估算

净初级生产力是陆地生态系统物质与能量运转研究的基础, 在干旱区生态环境演变及其与气候相互作用和影响方面极为敏感,是揭示干旱区生态环境特征的重要指标.本研究基于RS和GIS技术,利用地面气象数据、涡度相关数据、Landsat 8数据和MODIS数据,通过SEBAL模型和光能利用率模型的耦合,估算了新疆玛纳斯河流域植被净初级生产力(NPP),分析了其空间格局及与高程和坡度的关系.结果表明: SEBAL模型与光能利用率模型的耦合对玛纳斯河流域山地-绿洲-荒漠生态系统植被NPP的模拟效果较合理,能较好地反映植被净初级生产力的实际情况;2013年,玛纳斯河流域植被NPP总量为7066.72 Tg C·a^-1,平均值为278.06 g C·m^-2·a^-1,总体分布趋势是自南向北先增加后减少再增加最后减少,随着地貌和土地利用类型的变化呈现明显的分布规律,且其月变化比较明显,7—8月达到最大值,占总量NPP的52.2%;植被净初级生产力随海拔和坡度的增加整体呈下降趋势,但随海拔增加植被NPP出现3次波动.这些波动主要由地表植被覆盖类型和环境因素所引起.     

水氮互作对固定道垄作栽培春小麦根系生长及产量的影响

为探讨固定道小麦栽培方式下适宜的水氮组合,以低水1200 (W₁)、中水2400 (W₂)、高水3600 m³·hm^-2 (W₃)为主处理,0 (N₀)、低氮90(N₁)、中氮180 (N₂)、高氮270 kg·hm^-2 (N₃)为副处理,采用裂区设计,对固定道垄作栽培方式下水氮互作对春小麦根系生长及产量的影响进行了研究.结果表明:水氮互作能显著影响春小麦根干质量密度(RWD),RWD随着小麦生育期的进程表现为先增大后减小的趋势,在灌浆期达最大;RWD对施氮量的响应取决于灌溉量,在W₁下,RWD在N₁处理下最大,在W₂下,RWD随着施氮量的增加在N₂处理下最大,在W₃下,RWD随着施氮量的增加在N₃ 处理下最大;不同灌溉处理下RWD表现为W₂>W₃>W₁;施氮与灌水显著影响RWD,表现为灌水>氮肥>水氮互作,在W₂N₂处理下最大.根冠比随着灌水量与施氮量的增加逐渐减小,在W₁N₀处理下根冠比最大;85%以上的小麦根系分布于0～40 cm土层,产量与0～40 cm土层RWD呈显著抛物线回归关系,与40～60 cm土层RWD呈显著线性正回归关系.W₂灌溉条件可以促进小麦根系向中下层(40～60 cm)分布;灌水施氮能显著影响春小麦籽粒产量与生物产量,生物产量随着施氮量和灌水量的增加而增加,籽粒产量在W₂N₂最大;灌水生产力随灌水量的增加逐渐降低,氮肥农学利用率随施氮量的增加而减小.因此,在固定道垄作栽培方式下,施肥量与灌水量控制在N₂ (180 kg·hm^-2)与W₂(2400 m³·hm^-2)条件下有利于促进根系生长,进而提高春小麦籽粒产量及水氮利用效率,是河西灌区固定道小麦栽培方式下适宜的水氮组合.     

五种荒漠灌木群落土壤有机碳垂直分布及其与根系分布的关系

研究土壤有机碳与根系分布之间关系对评估碳储量和固碳潜力具有重要意义,而我国荒漠区灌木群落土壤有机碳与植物根系之间的关系尚不清楚。本研究选取深根性表层型灌木(表层根系生物量最大)梭梭(Haloxylon ammodendro)和中间锦鸡儿(Caragana intermedia)、深根性非表层型(表层根系生物量不是最大)灌木白刺(Nitratia tangutorum)、浅根性表层型灌木红砂(Reaumuria songarica)及浅根性非表层型灌木霸王(Sarcozygium xanthoxylon)为优势种的5种荒漠灌木群落为研究对象,测定100 cm深度内不同层次根系生物量及土壤有机碳含量,探讨灌木群落土壤有机碳的垂直分布格局及其与根系之间的关系。结果显示:(1)0~100 cm土壤有机碳密度与群落0~20 cm根系生物量碳密度显著正相关,与其他层次或累积深度不显著相关;(2)梭梭群落0~100 cm土壤有机碳密度显著低于与其他4个群落(P0.01),其他4个群落无显著差异(P0.05);(3)优势种为表层型的梭梭、中间锦鸡儿和红砂群落土壤有机碳密度与群落及优势种根系变化趋势一致,优势种为浅根性非表层型的霸王群落仅表层40 cm土壤有机碳与优势种灌木根系分布规律一致,优势种为深根性非表层型的白刺群落土壤有机碳与优势种根系分布规律一致。本研究表明,荒漠灌木群落0~100 cm土壤有机碳储量与群落0~20 cm根系生物量显著相关,群落优势种根系分布类型是影响土壤有机碳垂直分布格局的重要因素。     

Screening and identification of a microsatellite marker associated with sex in Wami tilapia, <Emphasis Type="Italic">Oreochromis urolepis hornorum</Emphasis>

In this study, primer pairs of 15 microsatellite markers associated with sex determination of tilapia were selected and amplified in Wami tilapia, Oreochromis urolepis hornorum. While one marker, UNH168, on linkage group 3 (LG3) was associated (P < 0.001) with the phenotypic sex in the experimental population, nine genotypes were detected in both sexes. Only 99-bp allele was detected in the female samples, while 141, 149 and 157-bp alleles were present in both male and female samples. UNH168 was localized by fluorescence in situ hybridization (FISH) on the long arm of the largest tilapia chromosome pair (chromosome 1, equivalent to LG3). This sex-linked microsatellite marker could potentially be used for marker-assisted selection in tilapia breeding programmes to produce monosex male tilapia.     

大兴安岭地区紫貂的活动节律

借助无线电遥测技术,对４只紫貂全年的活动节律进行了研究,结果表明,紫貂的活动节律春季和冬季的高峰是在晨昏二个阶段,夏秋二季的活动高峰在白昼。春季总体活动节律与夏季相比有明显差异（Ｆ＝４．４９９,ｄｆ＝１,２２,２３;Ｐ＝０．０４５）,春季与秋季的活动节律也有差异（Ｆ＝７．０３９;ｄｆ＝１,２２,２３;Ｐ＝０．０１５）。其总体平均活动强度,春季活动量最小（１７．５３％）,夏季最高（３８．２９％）,其     

钙调素的结构生物学研究进展

介绍了Apo-CaM、Ca²⁺-CaM以及CaM与其靶肽及拮抗剂复合体的空间结构.钙调素(calmodulin, CaM)作为细胞多功能的Ca²⁺受体,在细胞信号转导过程中发挥重要作用.近几年对它的空间结构有了较清楚的了解,使人们能够更明确地认识CaM的Ca²⁺激活及CaM与其靶酶的作用机制.     

蒙古栎红松林演替模型FOROAK的研究

Based on forest dynamics theory, gap model FOROAK was developed for simulating long-termdynamics of Mongolian oak (Quercus rnongolica Fisch. )-Korean pine (Pinus koraiensis Sieb. et Zucc. )forest. The model included two parts: biological growth and environmental impacts on growth. Different areapatches were used in simulating forest changes. The results showed that this forest gap was 0.05 hm2. Themodel testing demonstrated that it could reasonably simulate forest dynamic process, and had a very highaccuracy to predict species compositions. The observed species basal areas was similar to the predicted at 60,100 and 270 year forests, the observed species compositions were similar to the predicted at old forest period.Complex changes were found through modeling forest dynamics of bare ground. Mongolian oak and white birch( Betula platyphylla Sukacz. ) dominated at early stage, forest dominated by broad leaved species was formedat middle stage, and then Korean pine dominated at latter stage. The prediction of current primary forestshowed that it was steady during the next 300 year period, the number of trees and the biomass of Korean pine changed very little.     

Effects of High K+ and Alkaline pH on Ultrastructure of Dunaliella salina Chloroplasts

It was reported that the growth of Dunaliella salina Teod. cultured in medium containing 1 mol/L NaC1 was almost completely inhibited by the addition of 100 mmol/L KC1. The high K+ (100 mmol/L KC1) treatment also significantly inhibited the photosynthetic rate of D. salina and decreased chlorophyll contents in algae. This study focuses on possible effects of high K+ or alkaline pH on the ultrastructural change of chloroplasts in D. salina. After D. salina was cultured in a medium containing 100 n,anol/L KC1 or in a medium with alkaline pH for 8 to 10 days, dramatic ultrastructural changes occurred in the chloroplasts including thylakoid swelling, volume increase of chloroplast, and significant accumulation of starch grains in chloroplasts. The results are consistent with our previous report indicating that the ultrastmctuml changes in chloroplast under high K + or alkaline pH may lead to an inhibitory effects on photosynthesis and overall growth of D. salina.