CMIP6模式对中国西南部地区植被碳利用率模拟能力综合评估

中国西南部地区地形复杂,生态系统和植被类型丰富多样,是重要的生态资源区。受气候变化和人类活动影响,其生态屏障作用不断被减弱,准确评估该地区的植被碳利用率(CUE)对揭示碳平衡机理和预测陆地碳收支具有重要意义。该研究利用2001–2014年MODIS遥感观测数据和参加第六次国际耦合模式比较计划(CMIP6)的15个模式模拟数据,分别从年和季节尺度综合分析了新一代模式对中国西南部地区植被CUE的模拟能力,并基于综合评级指标(MR)对模式的模拟能力进行排名,以寻求模拟能力较好的模式,旨在有效降低未来预估结果的不确定性。结果表明:(1)大多数模式对年尺度区域平均植被CUE的模拟存在低估情况,且对植被CUE空间变化趋势的模拟能力相对较差,但部分模式可以较好地模拟出多年平均植被CUE空间分布,其中位于前1/3的较优模式依次为BCC-CSM2-MR、CMCC-ESM2、TaiESM、EC-Earth3-Veg、CAS-ESM2-0;(2)四个季节中,各模式对夏季多年平均植被CUE空间分布模拟能力最优,其中位于前1/3的较优模式依次为BCC-CSM2-MR、EC-Earth3-Veg、TaiESM、CMCC-ESM2、CAS-ESM2-0,各模式对冬季的模拟能力仅次于夏季,而春季和秋季则相对较差;(3)相较于单一模式而言,较优模式的集合在一定程度上可以削弱单一模式带来的不确定性,且在各时间尺度都表现出了较强的模拟能力,尤其可以合理再现四川盆地等局部地区植被CUE空间分布特点,但是对青藏高原以及横断山区等地形复杂区域植被CUE空间分布的模拟能力仍存在不足。总体来说,在使用CMIP6模式进行区域植被CUE模拟前,从多角度展开多模式的综合评估以挑选出模拟性能较好的模式是十分必要的。

中国西南部地区植被对极端气候事件的响应

在全球气候变化背景下,极端气候事件频发。中国西南部地区植被对于气候变化及极端气候事件的响应较为敏感。为探究西南部地区植被对极端气候事件的响应程度,该文采用Pettitt检验、趋势分析法对数据进行分析,并对数据进行去趋势处理,分析去趋势前后极端气候指数与归一化植被指数(NDVI)的相关关系。结果表明:(1)1982-2015年西南部地区植被NDVI呈现显著上升的趋势,NDVI在1994年发生突变,突变前上升不显著,突变后呈现显著上升的趋势;(2)去趋势前,1982-2015年间,极端降水指数与NDVI显著相关的仅有1日最大降水量,其与NDVI显著正相关;除气温日较差外,其他极端温度指数均与NDVI显著相关。1994-2015年间,1日最大降水量与NDVI显著正相关,降水日数与NDVI显著负相关;在极端温度指数中,日最低气温最大值、暖昼日数、夏季日数、生长季长度和气温日较差与NDVI显著正相关,冷昼日数、冰冻日数、冷夜日数和霜冻日数与NDVI显著负相关。1982-2015年间NDVI对年平均气温的响应最强,而在1994-2015年间NDVI对夏季日数和气温日较差的响应强于对年平均气温的响应。(3)去趋势后,极端降水指数与NDVI的相关性在两个时段都不显著;而日最高气温最大值、暖昼日数、夏季日数和气温日较差在这两个时段与NDVI显著正相关,但其与NDVI的相关系数都在1994-2015年间更高。气温日较差在两个时段与NDVI的相关系数都最高。只在1982-2015年冷昼日数与NDVI显著负相关。

Livelihood changes and evolution of upland ethnic communities driven by tourism:a case study in Guizhou Province,southwest China

As an effective livelihood approach to alleviate poverty without rural population migration, ethnic tourism has become the primary choice of economic development in ethnic areas worldwide in addition to traditional livelihood approaches. This article applies the theories of livelihood to study the community evolution driven by tourism livelihood and examine three mountainous tourism communities in different stages of tourist area life cycle. Drawing on the methods of GIS spatial analysis, semi-structured interviews and questionnaires, this article proposes a sustainable livelihood framework for ethnic tourism to explore the evolution of ethnic tourism communities by identifying changes in livelihood assets(natural, financial, social, cultural and human capitals) in the process of tourism development. The results show that the development of ethnic tourism has led to changes in the increase of building land, and the diversification of land use functions with a trend of shifting from meeting local villagers' living needs to satisfying tourists, income composition and uneven distribution of tourism income spatially. Ethnic tourism also led to the deterioration of traditional social management structure, collapse of neighboring relationship, the over- commercialization and staged authenticity of ethnic culture, as well as the gradual vanish of agricultural knowledge with a trend of increasing modern business knowledge and higher education. In addition, these changes, involving livelihood assets from natural, economic, human, social and cultural aspects are interrelated and interactive, which form new evolution characters of ethnic community. This study reveals the conflicts over livelihood approaches which have formed new vulnerabilities to impact on sustainable evolution of ethnic communities. This research provides implications for achieving the sustainable development of ethnic communities with the driving force of tourism livelihood.

Chemical characteristics of rainwater in karst rural areas,Guizhou Province, Southwest China

The chemical composition of rainwater has been studied in a karst rural area from September 2012 to August 2013 in Guizhou Province,Southwest China.The results indicated that the VWM value of p H was 5.4,varied from 4.6 to 6.9.Ca^(2+)and NH_4^+were the major cations,and SO_4^(2-)was the dominant anion.Neutralization factors show that the acid was mainly neutralized by Ca^(2+),NH_4^+and Mg^(2+).Investigations of correlation coefficients and enrichment factors revealed that Ca^(2+)and Mg^(2+)were mainly crust origins,and NH_4^+was from agriculture and livestock manure.SO_4^(2-)and NO_3^-were mainly from anthropogenic sources.

Modeling of the Second Indirect Effect of Anthropogenic Aerosols in East Asia

This study investigated the second indirect climatic effect of anthropogenic aerosols,including sulfate,organic carbon(OC) ,and black carbon(BC) ,over East Asia.The seasonal variation of the climatic response to the second indirect effect was also characterized.The simulation period for this study was 2006.Due to a decrease in autoconversion rate from cloud water to rain as a result of aerosols,the cloud liquid water path(LWP) ,and radiative flux(RF) at the top of the atmosphere(TOA) changed dramatically,increasing by 14.3 g m-2 and decreasing by-4.1 W m-2 in terms of domain and annual average.Both LWP and RF changed most in autumn. There were strong decreases in ground temperature in Southwest China,the middle reaches of the Yangtze River in spring and autumn,while maximum cooling of up to-1.5 K occurred in the Chongqing district.The regional and annual mean change in ground temperature reached-0.2 K over eastern China.In all seasons except summer,precipitation generally decreased in most areas north of the Yangtze River,whereas precipitation changed little in South China.Precipitation changed most in summer,with alternating bands of increasing(～40 mm) and decreasing(～40 mm) precipitation appearing in eastern China.Precipitation decreased by 1.5-40 mm over large areas of Northeast China and the Huabei Plain.The domain and annual mean change in precipitation was approximately-0.3 mm over eastern China.The maximum reduction in precipitation occurred in summer,with mean absolute and relative changes of-1.2 mm and-3.8%over eastern China.This study revealed considerable climate responses to the second indirect effect of aerosols over specific regions of China.

Seismotectonic Zonation of the Longmengshan and Chengdu Region

The principle of three-level delineation is adopted in determination of a potential seismic source for the new National Seismic Ground Motion Parameters Zoning Map of China,to embody the inhomogeneity of the spatial distribution of background seismic activity and induct a uniform seismotectonic model for each seismotectonic region. Based on achievements of determining potential seismic sources in southwestern China,this paper introduces the basic characteristics, historical earthquakes magnitude and frequency distribution,identification of deformation mechanism of main active tectonic structures for the Longmenshan and Chengdu seismotectonic region in the Longmenshan seismic region,establishes the seismogenic model for each seismotectonic region,and identifies the upper limit of background earthquakes. A simple method is also put forward for calculating the spatial distribution function of a background seismic source.

Palynomorph assemblages from the Fenghuoshan Group,southern Qinghai,China:their age and palaeoenvironmental significance

The varicoloured Fenghuoshan Group occurs widely in the Qiangtang-Hoh Xil region of the northern Qinghai-Xizang Plateau. Few fossils have been found to date in this sedimentary succession because lithological conditions are not conducive to their preservation. As a result, there has been a long-term disagreement among geologists about its age. Despite a few lists of fossil names in individual publi- cations, no detailed research on the palaeontology, including palynology, has been reported previously. In this study, we recovered many pollen grains and spores from two samples that were collected on the northern slope of Fenghuo Moun- tain. They indicate an age no younger than Maastrichtian for the upper part of the Fenghuoshan Group. It is considered likely that the entire Fenghuoshan Group represents deposi- tion between the late Early Cretaceous （possibly Albian） and the Maastrichtian. The palynoflora consists mainly of angio- sperm pollen, gymnosperm pollen and fern and bryophyte spores being subordinate. Pollen grains referable to the Ephedrales and the Taxaceae-Cupressaceae groups dominate the assemblage, implying a warm, arid climate and subtropical forest-shrub vegetation at the time of deposition.