四季柚贮藏试验初报

通过分析不同采摘时期、不同冷藏时期的四季柚果实理化成分的变化，探讨四季柚树藏、冷藏保鲜效果，为四季柚延长供果模式提供理论根据。

给陈蕴珍——1972年于北京

……她动身去医院……她显得急躁,又有些留恋,东张张西望望,她也许在想是不是能再看到这里的一切.临出门时,见到信箱中的这封信,我拿给萧珊看了.萧珊患了不治之病,得不到适当的治疗,躺在床上捱日子,想念过去的岁月,怀念旧时的友人,最后入院前忽然得到北京沈从文寄给我的一封长信,她含着眼泪拿着信纸翻来复去地看,小声地自言自语:“还有人记得我们啊.

Dynamics of profiles and storage of carbon dioxide in broadleaved/Korean forest in Changbai Mountain

CO2 concentrations at different heights in a broadleaved/Korean forest (with a mean height of 26 m) were measured with infrared gas analyzer IRGA (model 2250D, LI-COR Inc. and LI-COR, 820) from Aug. to Oct. of 1999, Apr. to Jul. of 2000, and from Aug. 2002 to Sept. 2003. Based on the collected dada, the diurnal and seasonal dynamics of profiles and storage of carbon dioxide in the forest were analyzed. The diurnal CO2 profiles showed that the vertical distribution of CO2 concentration were different for daytime and nighttime, and the CO2 concentration was highest close to forest floor, no matter at daytime and nighttime. The seasonal profiles of CO2 showed that stratification in the canopy was evident during growth season. CO2 concentrations at different heights (60 m to 2.5 m) had a little change in March, with a difference of 10 mmolmol-1, but had a significant change in July, with a difference of 60 mmolmol-1. In July, there also existed a greater gradient of CO2 concentrations at canopy (22, 26 and 32 m), with a difference of 8 mmolmol-1. The calculated total storage (ΔC/Δt ) of CO2 in the air column with height of 40 m beneath eddy covariance instrument was negative, and made a little contribution to NEE.

北方风景三题

北方风景三题●肖峰树一叶障目，不见泰山。对于树来说，有了一身绿衣，它还能看到什么？风从它身上经过的时候，感觉到自己的微弱。是啊，树太沉重了。我们为什么那样倾心叶子？不由得想起北方的树挂，在白雪皑皑的季节，一眼就看到了它。在季节的界限上，整个冬天都让人...

Effect of Acorn Burying Depth on Germination, Seedling Emergence and Development of Quercus aliena var. acuteserrata

Acorns of Quercus aliena var. acuteserrata Maxim. are often predated by small mammals and birds in natural forests. These animals not only eat the acorns during the acorn ripening season, but also cache and hoard most of the remaining acorns on the forest floor in the soil for their future use. These buried acorns form the main seed resource for regeneration. Burying depth is potentially important for germination and for seedling development. The effects of burying depth on germination and seedling development in relation to acorn size were studied in an experiment, in which acorns were planted at 6 cm-, 12 cm- and 18 cm-depth. The experimental results showed that fewer acorns germinated as burying depth increased. From the deeply buried acorns fewer seedlings emerged at later time than from those acorns buried less deeply. They appeared to have more difficulties to emerge above-ground than die seedlings from shallowly buried acorns. The deeply buried acorns and their seedlings also appeared to be more susceptible to rot. Acorn size did not significantly affect germination and emergence of the seedlings. As early emerged seedlings had longer developmental periods in their first growing season, and therefore grew better than die late emerged seedlings, seedlings from die shallowly buried acorns took the advantage.

Allometric equations of select tree species of the Tibetan Plateau, China

The Tibetan forest is one of the most important national forest zones in China. Despite the potentially important role that Tibetan forest will play in the Earth?s future carbon balance and climate regulation, few allometric equations exist for accurately estimating biomass and carbon budgets of this forest. In the present study, allometric equations,both species-specific and generic, were developed relating component biomass(DW) to diameter at breast height(DBH) and tree height(H) for six most common tree species in Tibetan forest. The 6 species were Abies georgei Orr., Picea spinulosa(Griff.)Henry, Pinus densata Mast., Pinus yunnanensis Franch., Cypresses funebris Endl. and Quercus semecarpifilia Smith.. The results showed that, both DBH-only and DBH2 H based species-specific equations showed a significant fit(P<0.05) for all tree species and biomass components. The DBH-only equations explained more than 80% variability of the component biomass and total biomass, adding H as a second independent variable increased the goodness of fit, while incorporating H into the term DBH2 H decreased the goodness of fit. However, not all DBH-H combined equations showed a significant fit(P<0.05) for all tree species and biomass components. Hence, the suggested species-specific allometric equations for the six most common tree species are of the form ln(DW) = c + αln(DBH). The generalized equations of mixed coniferous component biomass against DBH, DBH2 H and DBH-H also showed a significant fit(P<0.05) for all biomass components. However, due to significant species effect, the relative errors of the estimates were very high. Hence, generalized equations should only be used when there are too many different tree species, or there is no species-specific model of the same species or similar growth form in adjacent area.

Medical mountain rescue in the Yushu Earthquake: Have lessons been learned?

On April 14,2010,an earthquake reaching Richter scale 7.1 struck Jiegu Town of Yushu,a mountain rescue operation promptly launched. All injurers had a direct assess to take medical care,and were immediately rescued and rapidly evacuated by air to Xining and Golmud at lower altitudes and admitted to advanced hospitals. Almost all of the injurers have been completely recovered. Yushu Earthquake was one of the highest earthquakes in the world,with a high incidence of acute altitude illness,which was observed in about 80 % of the lowland rescuers at an altitude of 4 000 m."Rescue the rescuers"became the major task of Qinghai-Tibetan rescue teams,all the severe patients were rapidly descended to Xining and treated promptly and effectively. The outcome was excellent,all patients survived. After the earthquake,it is a long and arduous task to reconstruct what has been destroyed. Medical teams continue to work in the Yushu Earthquake area because about 30 000 workers and carders are now here for rebuilding the earthquake center. Thus the prevention and treatment of altitude illness are still critical tasks for medical teams. Although all the fights are successful,there are more experiences and lessons we have learned from the medical mountain rescue during the earthquake and the reconstruction,and reports here are to sum up our experiences from the medical mountain rescue operation in Yushu Earthquake and draw the lessons that we should learn. With the increasing of earthquake probability occurring in the Qinghai-Tibetan Plateau,we also should prepare against earthquake disasters and for further rescue training in the high mountains.

Channel Selection Information Hiding Scheme for Tracking User Attack in Cognitive Radio Networks

For the discontinuous occupancy of primary users in cognitive radio networks(CRN),the time-varying of spectrum holes becomes more and more highlighted.In the dynamic environment,cognitive users can access channels that are not occupied by primary users,but they have to hand off to other spectrum holes to continue communication when primary users come back,which brings new security problems.Tracking user attack(TUA) is a typical attack during spectrum handoff,which will invalidate handoff by preventing user accessing,and break down the whole network.In this paper,we propose a Channel Selection Information Hiding scheme(CSIH) to defense TUA.With the proposed scheme,we can destroy the routes to the root node of the attack tree by hiding the information of channel selection and enhance the security of cognitive radio networks.

Changing the Moisture Content of the Spartina and Miscanthus and Willow Shoots during Storage in Natural Conditions

The aim of this study was to determine the characteristics of the distribution of energy plant moisture content along the height of their shoots and the dynamics of moisture during storage in natural conditions. The shoots of Spartina, Miscanthus and willow were used in the study. Entire shoots were cut into sections of 10 cm and for each set in monthly cycles for six months moisture content was evaluated. After a month＇s storage of freshly cut shoots the biggest decrease of content moisture in the shoots of Spartina and Miscanthus was recorded, by 31% and 22%, respectively, and the lowest in willow shoots （12%）. After sixth months of shoots storage the lowest moisture content （10%-12%） was reached in miscanthus. The most uneven moisture content along the height of shoots Spartina was characterized because on one third of the height from the bottom, the moisture content of shoots was 20%, and the top had moisture content in the range 5%-10%. Willow shoots were characterized by the smallest drop in moisture, and the final moisture content was about 23%, with the top part of moisture content of 10%-20%. The dynamics of moisture change during the six months of storage of grass shoots （Miscanthus and Spartina） in natural conditions under roofing was described by one power function regression, and willow by another one. Empirical models can be used to predict changes in moisture content of these plants in experiment conditions, since the coefficients of determination were 94.66% and 89.18%, respectively.

Positive adaptation of Salix eriostachya to warming in the treeline ecotone,East Tibetan Plateau

Understanding of treeline ecotone ecophysiological adaptation to climate warming is still very limited. Furthermore, it is difficult to predict which plant species could dominate in the future. For this reason, a study was conducted in the treeline ecotone, East Tibetan Plateau to detect the adaptation of the dwarf willow(Salix eriostachya) to experimental warming. Compared to ambient conditions, the experimental warming advanced the bud break by 12 days, delayed the leaf abscission by20 days, and prolonged the growing period by 28 days.It also increased photosynthesis(47%), number of leaves(333%), leaf area(310%), and carbon sequestration of the dwarf willow. Experimental warming did not affect carbon use efficiency, but decreased water use efficiency significantly.Experimental warming enhanced the clonal ramets of Salix eriostachya(+ 3.7 shrubs m-2). The frequent air temperature fluctuations had minor effect on Salix eriostachya. Based on these findings, we highlighted that Salix eriostachya could dominate in the community treeline ecotone of east Tibetan Plateau in the future climate warming scenario.

Tree Rings Tell Moisture Variability on Tibetan Plateau

Tibetan Plateau（TP）is known as＂Asia’s Water Tower＂,but it remains an interesting question whether the water supply to the north of the plateau is the same with that to the south.Dr.ZHANG Qibin and coworkers from the State Key Laboratory of Vegetation and Environmental Change.CAS Institute of Botany recently tried to answer it from their studies of tree rings.They found evidences for different moisture conditions on the north and south of the plateau during the past five and a half centuries,and particularly,

Analysis of Spatial-Temporal Changes in the Landscape Structure of Yushu Prefecture in Qinghai Province

Yushu Tibetan Autonomous Prefecture, an area located in the Qinghai-Tibet Plateau, is an area very sensitive to global climate change. Due to impacts from climate change and human disturbances, grassland vegetation in the area has been degraded and desertification has been expanding. Ecosystems in the area are very sensitive and fragile and ecological problems have become increasingly serious in the area, resulting in an adverse effect on the local socio-economic development and environment of Qinghai province. Using data gathered from Landsat TM/ETM images for 1987, 1997 and 2007, we analyzed landscape patterns across Yushu Prefecture. Spatial structure indices indicated that： （i） the area of grassland has significantly decreased in the form of degradation and conversion from grassland into bare land and farmland; （ii） grassy vegetation patches changed into fragmented and isolated patches; （iii） the main landscapes in Yushu Prefecture are grasslands, forests and rivers; （iv） patches of grass have reiatively high connectivity; and （v） landscape change is significantly correlated with human activities and climate change. This study provides a strong theoretical and technical basis for policy-making regarding environmental protection of and management in Yushu Prefecture of Qinghai Province.

Tree ring-dated fluctuation history of Midui glacier since the Little Ice Age in the southeastern Tibetan Plateau

Fluctuation history of Midui glacier in the southeastern Tibet since the Little Ice Age(LIA) was reconstructed by the dating of lateral and terminal moraines using tree rings.Four conversions of glacier advance/stabilization to retreat were identified at around 1767,1875,1924 and 1964.The glacier reached its LIA maximum position at 1767.The fluctuations are consistent with those of other glaciers from the Tibetan Plateau,the Rockies and the Alps,suggesting high spatial coherency of glacier fluctuations in the Northern Hemisphere.Comparison with the summer temperature reconstruction in the southeastern Tibetan Plateau indicated that the Midui glacier fluctuation may be related to temperature variation on the centennial timescale.On the decadal scale,the fluctuation could correspond to cold/warm variation with an 8-year lag on average.