气候因素对木材细胞结构的影响

综述针叶材年轮内管胞个数、尺寸、壁厚和树脂道个数及阔叶材年轮内导管个数和尺寸等木材细胞结构对温度和降雨的响应。影响木材细胞结构的因素除气候外,还有非气候因素,在研究木材细胞结构对气候变化响应时,应尽可能地考虑到后者的影响。本文也综述一些非气候因素,如地形、土壤、海拔、大气污染、病虫害、种植密度、施肥和灌溉等对木材细胞结构的影响,以期充分认识影响木材细胞结构的因素,为木材细胞结构对气候变化响应的研究和林业应对气候变化提供参考。

中英格兰地区逐日温度序列重建

文章介绍了哈得莱气候预测与研究中心Parker等在 1992年重建中英格兰地区始于 1772年的均一性逐日温度序列的方法 ,该序列 1772～ 1876年间是建立在单站基础上的 ,剩余时段是用几个台站合并加工而成。并介绍了Parker等通过与附近乡村站点的比较 ,对序列近年来城市增暖进行评估和订正的方法 ,最后还剔除了序列中非气候因素所造成的影响。结果表明 ,Parker等对序列重建和订正的方法是恰当的 ,但城市增暖引起的不确定性依然存在 ,所以保持站点位置、观测方法。

Relict glacial landscape in the Sierra Baguales Mountain Range(50°-51°S):evidence of glaciation dynamics and types in the eastern foothills of the southern Patagonian Andes

The glacial morphology of southern South American presents invaluable evidence to reconstruct former glacier behaviour and its relation to climate and environmental changes. However, there are still spatial and temporal gaps in the reconstruction of the Holocene Patagonian glacial landscape. Here we present the first geomorphological record for the Sierra Baguales Mountain Range(SBMR), forming the eastern foothills of the Southern Patagonian Andes 200 km from the Pacific coast. This area is topographically isolated from the Southern Patagonian Ice Field(SPIF), and is affected by the Westerly Winds. The study area shows evidence of ice sheet and alpine glaciations related to Andean uplift,which caused a marked climatic contrast between its western and eastern flanks since the Last Glacial Maximum(LGM). The regional rock mass strength and precipitation gradient acted as a controlling factor in the glacial cirque distribution and sizes, as well as in the development of glaciation types. We report new radiocarbon dates associated with warm/dry to cold/wet climatic changes during the middle Holocene, when former small alpine glaciers were located in the uppermost section of the SBMR basins, and eventually converged to form a small ice field or a composite valley glacier at lower elevations.This can be explained by an estimated regional temperature drop of 3.8°C±0.8°C, based on a 585±26m Equilibrium Line Altitude(ELA) descent, inferred by geomorphological evidence and the Accumulation Area Ratio(AAR), in addition to a free-air adiabatic lapse rate. Subsequently, the glaciers receded due to climatic factors including a rise in temperature, as well as non-climatic factors, mainly the glacier bedrock topography.

气候变化对海岸带影响与风险评估技术

针对气候变化影响和风险评估的关键技术问题，系统评估过去30年气候变化对我国海岸带风暴潮、海浪、海冰等自然致灾因子，海平面上升及海岸带湿地生态等的影响，定量分离气候和非气候因素的影响，揭示过去30年气候变化对海岸带有关因子的影响程度及其区域差异；发展中国气候变化影响海洋灾害等风险评估关键技术。

Response of forest distribution to past climate change: An insight into future predictions

Vegetation dynamics could lead to changes in the global carbon and hydrology cycle,as well as feedbacks to climate change.This paper reviews the response of forest dynamics to climate change.Based on palaeoecological studies,we summarized the features and modes of vegetation response to climate change and categorized the impacts of climate change on vegetation dynamics as three types:climate stress on vegetation,buffer effects by non-climatic factors,and perturbation of the vegetation distribution by stochastic events.Due to the openness of the vegetation system and the integrated effects of both climatic and non-climatic factors,the vegetation-climate relationship deviates far from its equilibrium.The vegetation distribution shows a non-linear response to climate change,which also makes it difficult to quantify the modern vegetation distribution in terms of specific climatic factors.Past analog,space-for-time-substitution and Dynamic Global Vegetation Models(DGVMs)are three approaches to predicting the future vegetation distribution,but they have all been established on the assumption of vegetation-climate equilibrium.We propose that improving DGVMs is a future task for studies of vegetation dynamics because these are process-based models incorporating both disturbance(e.g.fire)and the variability in Plant Functional Types(PFTs).However,palaeoecological results should be used to test the models,and issues like spatial and temporal scale,complexity of climate change,effects of non-climatic factors,vegetation-climate feedback,and human regulation on vegetation dynamics are suggested as topics for future studies.

Thermokarst lake changes between 1969 and 2010 in the Beilu River Basin, Qinghai–Tibet Plateau, China

This work presents changes of thermokarst lakes from Beilu River Basin on the Qinghai-Tibet Plateau over the past four decades （1969-2010） using aerial and satellite image interpretation. The results indicated that thermokarst lake activity had generally increased rapidly between 1969 and 2010. The number of thermokarst lakes had increased by approximately 534, and their coverage expanded by about 410 ha. The two main changes observed were an increase in the number of small lakes and the expansion of larger lakes. These changes are likely the result of persistent climate warming and a gradually increasing imbalance between precipitation and evapotranspiration （PET）. However, some non-climatic factors, such as the lake-bottom substrate and local engineering activities, have also influenced the lake changes. If air temperature and P-ET continue to rise, the number of thermokarst lakes and the area they cover may continue to increase in the future.

Soil Microbial Activities in Beech Forests Under Natural Incubation Conditions as Affected by Global Warming

Microbial activity in soil is known to be controlled by various factors. However, the operating mechanisms have not yet been clearly identified, particularly under climate change conditions, although they are crucial for understanding carbon dynamics in terrestrial ecosystems. In this study, a natural incubation experiment was carried out using intact soil cores transferred from high altitude(1 500 m) to low(900 m) altitude to mimic climate change scenarios in a typical cold-temperate mountainous area in Japan. Soil microbial activities, indicated by substrate-induced respiration(SIR) and metabolic quotient(q CO2), together with soil physicalchemical properties(abiotic factors) and soil functional enzyme and microbial properties(biotic factors), were investigated throughout the growing season in 2013. Results of principal component analysis(PCA) indicated that soil microbial biomass carbon(MBC) andβ-glucosidase activity were the most important factors characterizing the responses of soil microbes to global warming. Although there was a statistical difference of 2.82 ℃ between the two altitudes, such variations in soil physical-chemical properties did not show any remarkable effect on soil microbial activities, suggesting that they might indirectly impact carbon dynamics through biotic factors such as soil functional enzymes. It was also found that the biotic factors mainly controlled soil microbial activities at elevated temperature,which might trigger the inner soil dynamics to respond to the changing environment. Future studies should hence take more biotic variables into account for accurately projecting the responses of soil metabolic activities to climate change.