The forest ecosystem plays a significant role in long-term carbon sequestration. The magnitude of a forest carbon sink is determined by the combination of intrinsic biotic factors (i.e. forest age) and extrinsic environmental driving factors (i.e. temperature, precipitation, nitrogen deposition). The mechanism of how forest age affects the carbon balance is still unclear. Furthermore, forest age is a useful surrogate variable for analyses of the impact of disturbances on forest carbon and an important parameter for assessing carbon mitigation potential of forests at regional scale. Without considering forest age, large uncertainties exist in the simulating forest carbon cycle at regional scale. In this study, we analyzed the effect of forest age information on carbon uptake of China’s forests based on a process-based model (Integrated Terrestrial Ecosystem Carbon budget, InTEC model) in the last century, with integration of two forest age maps at 1 km spatial resolution which were derived from inventory data and remote sensing AVHRR NDVI. Inter-annual variability of net primary productivity in China’s forests during 1901–2010 based on InTEC model coupled with inventory data and remote sensing data was similar with each other. Meanwhile, the comparison approach indicated that the errors of 5 years in forest age might cause uncertainties of 25% in simulated net ecosystem productivity of China’s forests. We also discussed the significance of forest age in ecosystem process-based model and the uncertainties of carbon balance of China’s forest ecosystem during 1901–2010. Besides, the hypothesis assumed that no large-scale deforestation occurred since1950s and mature forests (and older forests) were covered the whole China. We adjusted forest age structure for different forest types and regions to simulate the effect of changes in forest age on distribution of carbon balance in China. The important finding is that the loss of carbon sink in China’s forests induced by disturbances (i.e. deforestation, afforestation or natural disturbances) is about 3.80 Pg C during last century. Based this hypothesis, China’s forests in the last two decade manifested a large carbon sink (0.23 Pg C a - 1). Currently, many process-based models are not capable of reflecting the impact of land disturbances because the explicit forest age information are lacking. Our study incorporated the forest age in models successfully and explored the effect of forest age on the simulating carbon balance of forests. The application of forest age in large-scale carbon modeling can improve the accuracy of simulated carbon dynamics and explore the uncertainties in carbon cycle models.

为探讨三江平原沼泽湿地变化对繁殖丹顶鹤(Grus japonensis)和白枕鹤(G.vipio)的影响,2007和2008年夏季我们对该区域展开了全面地面调查:同时,通过解译1986、1995、2000和2005年4个不同年份的卫星影像,获取了沼泽湿地变化信息.对比1984和2008年两次全面调查结果,发现:1)丹项鹤的数量基本稳定,维持在300只左右；而白枕鹤的数量呈现显著增加；2)两个年份中,丹顶鹤巢窝估计大抵相当,但两种鹤近90％的巢址均分布在5个国家级自然保护区境内；3)两种鹤类逐渐集中于3个分布区;抚远三角洲、挠力河和七星河中游,以及兴凯湖湿地；而不是以前的6个分布区.1986-2005年的20年间,三江平原沼泽湿地面积减少了45％.在不同经济和政策的驱动下,湿地丧失的直接原因是人类活动,将湿地逐渐转变为水田和旱地.嘟噜河和阿布沁河的鹤类消失,主要原因就是大规模的农业开发.沼泽湿地的破碎化和斑块化的程度越来越高,适宜鹤类繁殖的栖息地势必越来越少.1984-1995年间,丹顶鹤的数量呈现急剧下降；到2008年,数量基本得以恢复.这种变化主要归功于2000年以后,三江平原自然保护区体系的完善.其次,保护区的土地权属对于维持湿地生态系统的完整性起到了非常重要的作用,特别是三江、洪河、挠力河和七星河国家级自然保护区.这些保护区拥有整个三江平原80％的鹤类种群.遗憾的是,在一些省级和市级保护区境内,本次调查期间,未发现有鹤类营巢繁殖.这可能与比较高的人为活动干扰有关.最后,就自然保护区管理提出了一些建议.

A survey on current waterbirds community was conducted at Gengga Lake of Qinghai from April to November of 2010. This study was to establish waterbird baseline information for the surveillance of avian influenza and the wetland conservation and management at Genga Lake. A total of 27 416 individuals of 55 waterbird species,belonging to 12 families and 6 orders,were recorded in the survey. Geese and ducks were the most abundant species,accounted for 69. 0% of all waterbirds counted. There were over 12 000 waterbirds in October,with the most per month,and there was no significant difference in waterbird number among the other months. There were about 21 - 29 species per month from April to November. There were fewer feeding sites for geese and ducks in April due to the ice coverage at some areas of the lake,which might result in the some waterbirds deaths due to lack of food. Thousands of waterbirds often aggregated at resting and feeding areas in October,and many livestock often mixed with the wild fowls,increasing opportunity for infection of avian influenza among intra-and inter-species. Thus,April and October were the important periods for avian influenza surveillance.

A study on seasonal dynamic of waterbirds was conducted from 2008 to 2010 at Keluke Lake,Qinghai Province,China.The study was to establish waterbird baseline information for the surveillance of avian influenza and wetland conservation and management at Keluke Lake.A total of 34828 waterbirds,belonging to 54 species,11 families and 6 orders,were recorded during the survey.There were 28445 geese and ducks,accounting for 81.7% of all waterbirds counted,followed by gulls and shorebirds.April and October were two peak periods for spring and fall migrations of waterbirds at Keluke Lake,respectively.Satellite tracking on Great Black-headed Gulls Larus ichthyaetus breeding at Qinghai Lake of Qinghai province showed that Keluke Lake was an important stopover site of the gulls.The time they spent during fall migration varied between years.In 2007,the gulls stayed very short,likely resulted from a road construction occurring an area normally as the home range of the gulls.The timing of their arriving at the lake during spring migration possibly related to the ice melting at Qinghai Lake,the quicker the ice melted at Qinghai Lake,the earlier the gulls flew to Qinghai Lake from Keluke Lake.

Effective conservation and management of Bar-headed Geese (Anser indices) require data to determine migration routes and identify key sites for protection. Ten Bar-headed Geese were banded with satellite transmitters at Qinghai Lake in western China in July 2006 and 2007 to determine their migration routes. Of the tagged geese, eight left Qinghai Lake and began autumn migration. Of these eight, four completed their autumn migration, lasting 50 to 90 days, using one of two migration routes to their wintering grounds near Caohai Lake in Guizhou Province, Yarlung Zangbo valley in Tibet, and Kohima in India. The tagged geese each stopped at three to four sites and traveled 1,270 to 1,470 km from their breeding to wintering grounds. Wetlands at Muli Marsh, Zhaling, Eling and Galalacuo Lakes in Qinghai Province, Nagqu and Damxung in Tibet, and Ruoergai Marsh in Gansu and Sichuan Provinces were used as major stopover sites. Received 3 February 2010, accepted 1 August 2010.

A survey on current status of waterbirds was conducted at Hangcuo Lake of Tibet from April to November of 2009,to help strengthen the wetland conservation and management and establish baseline information for the surveillance of avian influenza at Hangcuo Lake.A total of 26 waterbird species,belonging 10 families and 6 orders,were recorded during the survey.Over three thousands of Bar-headed Geese Anser indicus and Brown-headed Gulls Larus brunnicephalus were found breeding on the small island in the lake,suggesting Hangcuo Lake is an important breeding area for Bar-headed Geese and Brown-headed Gulls.With the highest diversity of waterbird species,especially remarkable increases in duck species and numbers,April and October were two peak periods for spring and fall migrations of waterbirds at Hangcuo Lake,respectively.Satellite tracking on the Bar-headed Geese showed that the geese mostly foraged in Hangcuo Lake and the surrounding wetlands in the early breeding period.In the mid-breeding period,the home range decreased dramatically,because the birds were spending much time in sitting on the nests.After the chicks were hatched,adult geese together with their fledglings,left Hangcuo Lake for other wetlands for foraging and chick-rearing.That movement by goose families after hatching possibly was due to decreasing food resources at Hangcuo Lake and resulted in a larger home range in the late breeding period comparing to the mid-breeding period.By the time just before the fall migration started,the numbers of Bar-headed Geese increased remarkably again,as a result of many Bar-headed Geese coming back from nearby wetlands and immigrating from the north to Hangcuo Lake.Hangcuo Lake had fewer number of waterbird species than Qinghai Lake,most likely due to the high altitude,strong ultraviolet radiation,dry weather,and poor habitat diversity of vegetation communities at Hangcuo Lake.

A HPAI (High Pathogenic Avian Influenza) outbreak in 2005 resulted in several thousands Bar-headed Geese dying at Qinghai Lake, China, which draws attention to the need for a better understanding of the species. In this paper, the movements and habitat utilization of breeding Bar-headed Geese and their relationship with human beings in Qinghai Lake were documented through radio tracking and color marking. Bar-headed Geese breed at Dandao and feed at Quanwan, Garila, Heimahe Estuary and Tiebujia Estuary between March and September. Their home range and core area cover (309.63 ± 172.72) km 2 and (49.30 ± 19.6) 1 km2, respectively. There is no significant difference of home range size between different periods. Bar-headed goose shows strong site fidelity between different periods, with an average 56.6% ± 24.9% tracking points falling within the home range of earlier periods. However, the home range shows major differences between the mid-breeding period and late breeding period, because the parents leave the breeding ground with their offspring in latter. As the breeding season progresses, the geese use the estuary less and the marsh more. The Bar-headed Goose has a higher contact intensity with human-beings and livestock in Dandao, Heimahe and Quanwan and in the month of May, which indicates that enhancing tourism management and public awareness of local people is important.

The migration routes of Great Black-headed Gull and Bar-headed Goose breeding at Qinghai Lake were studied using satellite-tracking from July of 2006 to July of 2007.Four Great Black-headed Gulls and one Bar-headed Goose banded with satellite transmitters,arrived at their wintering sites and backed to Qinghai Lake in next year successfully.In this paper,the migration routes of Great Black-headed Gull and Bar-headed Goose were clarified,combining the application of satellite-tracking on birds migration,which provides the scientific evidences on the relationship between Avian Influenza and bird migration at Qinghai Lake,even at the Central Asia-India flyway.

2005年5月青海湖发生了严重的野生水禽感染高致病性禽流感病毒(H5N1)的事件,斑头雁Anser indicus、棕头鸥Larus brunnicephalus、渔鸥L.ichthyaetus和普通鸬鹚Phalacrocorax carbo等10余种水禽约6000余只死于禽流感病毒[1].为了弄清青海湖鸟类的资源状况,2006年3～9月、2007年1月和4～8月,我们于不同时期在青海湖重要的繁殖地和迁徙停歇地,以及青海湖周边山中的森林,对鸟类资源状况进行了调查.

The surveys on current status of waterbirds at Qinghai Lake were conducted from April to September of 2006 and 2007 with aim of assessing the Avian Influenza surveillance at Qinghai Lake.Higher species diversity was found in spring and autumn, migration season.The diversity declined at breeding season.The most encountering bird species in spring migration season and breeding season are Bar-headed Goose,Brown-headed Gull and Great Black-headed Gull,at the Buhahekou,Tiebuqiahekou,Quanwan and Grila.During autumn migration,the gulls and geese often rest and feeding in flock at Buhahekou,Quanwan and Heimahe.Finally,in this paper we provided some conservation suggestions on Avian Influenza surveillance at Qinghai Lake.

2006年4-9月, 采用彩色标记、无线电遥测和卫星跟踪等方法, 对青海湖四种繁殖水鸟斑头雁 (Anser indicus)、棕头鸥 (Larus brunnicephalus)、渔鸥 (L. ichthyaetus)和鸬鹚 (Phalacrocorax carbo)的活动区域进行了研究.采用"绳套法"捕捉了45只斑头雁, 其中6只于4月安装了无线电发射器, 6只于7月安装了卫星发射器; 采用"拉网法"捕捉了104只棕头鸥, 其中6只于4月安装了无线电发射器; 采用"绳套法"捕捉了51只渔鸥, 其中2只于4月安装了无线电发射器; 采用"扣网法"捕捉了75只鸬鹚, 其中6只于5月和6月安装了无线电发射器, 4只于8月安装了卫星发射器.通过研究, 获得了上述四种繁殖水鸟在青海湖的活动区域, 即: 斑头雁有3个主要的活动区域, 棕头鸥有1个, 渔鸥有4个, 鸬鹚有2个.其中从鸬鹚岛、蛋岛、布哈河口、铁卜恰河口至泉湾区域是上述四种繁殖水鸟共有的活动区域, 该区域也是春秋迁徙季节众多水鸟的重要取食地和停歇地.

The home range and movements of Brown-headed Gulls (Larus brunnicephalus) were studied using radio telemetry from April to September 2006 at Qinghai Lake, China. Six Brown-headed Gulls were banded with radio transmitters. The results showed that the average Brown-headed Gull home range was larger in the early breeding period because of searching for food and mates. During this period, the gulls were often seen at Luci Island, Egg Island and Buhahekou, where food was abundant. The average home range size reduced dramatically in the mid breeding period due to egg laying and incubation. The birds frequently congregated at Buhahekou, where schools of fish gathered from the main lake and began to spawn in the spring. In the late breeding period, Brown-headed Gulls had to travel far from their nests, such as upstream of Buhahekou and Quanwan, to look for food to raise their fledglings. During this period, the home range sizes started to increase again. When the fledglings were able to fly in the early migration period, the home range size increased almost to the same size as the early breeding period. The home range size in the early breeding, mid breeding, late breeding, and early migration period were respectively (15.48 km2±4.54 km2), (1.61 km2±0.41 km2), (3.53 km2±2.63 km2), and (11.61 km2±9.36 km2).

The surveys on current status of waterbirds at 15 sites of Qinghai Lake were conducted from April to September of 2006, with the aim of further strengthening the conservation and management of wetlands at Qinghai Lake. Totally 68 species were recorded, under the 7 orders, 12 families. Of 68 species recorded during the investigations, 15 species were firstly observed at Qinghai Lake. Spring migration peak of waterbirds at Qinghai Lake is at the end of April. The waterbird diversity varied with different habitats, and there was lower diversity at sandy habitats such as Luci Island and Erlangjiang, resulted from the lower food richness at sandy habitats.