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Response of density-related fine root production to soil and leaf traits in coniferous and broad-leaved plantations in the semiarid loess hilly region of China

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Journal of Forestry Research 2022年第3期33卷 1071-1082页

作者： Meimei Sun Bo-Chao Zhai Qiu-Wen Chen Guoqing Li Sheng Du State Key Laboratory of Soil Erosion and Dryland Farming On the Loess Plateau Northwest A&F UniversityYanglingShaanxi712100People’s Republic of China College of Forestry Northwest A&F UniversityYanglingShaanxi712100People’s Republic of China Institute of Soil and Water Conservation Chinese Academy of Sciences and Ministry of Water ResourcesYanglingShaanxi712100People’s Republic of China

Fine roots are the most active and functional component of root systems and play a significant role in the acquisition of soil resources. Density is an important structural factor in forest plantations but information on changes in fine roots along a density gradient is limited. In this study, plantations of black locust (Robinia pseudoacacia L.) and Chinese pine (Pinus tabuliformis Carr.) with four density classes were analyzed for the influence of soil and leaf traits on fine root growth. Fine root biomass increased with stand density. High fine root biomass was achieved through increases in the fine root production and turnover rate in the high-density black locust plantations and through an increase in fine root production in the pine plantations. In the high-density Chinese pine stand, there was a high fine root turnover which, coupled with high fine root production, contributed to a high fine root biomass. Overall, fine root production and turnover rate were closely related to soil volumetric water content in both kinds of plantations, while fine root biomass, especially the component of necromass, was related to soil nutrient status, which refers to phosphorous content in black locust plantations and nitrogen content in Chinese pine plantations. There was a close linkage between leaf area index and fine root dynamics in the black locust plantations but not in the pine plantations.

关键词： Fine roots Black locust Chinese pine semiarid Soil moisture Leaf area index

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Impact of spatiotemporal land-use and land-cover changes on surface urban heat islands in a semiarid region using Landsat data

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International Journal of Digital Earth 2021年第2期14卷 250-270页

作者： Ehsan Kamali Maskooni Hossein Hashemi Ronny Berndtsson Peyman Daneshkar Arasteh Mohammad Kazemi Department of Watershed Management and Engineering University of HormozganBandar-AbbasIran Centre for Middle Eastern Studies&Division of Water Resources Engineering Lund UniversityLundSweden Water Science and Engineering Faculty of Agriculture and Natural ResourcesImam Khomeini International UniversityQazvinIran

Many factors are involved in urban heat island development,such as lack of green spaces,improper choice of building materials,densification,and other human activities.The aim of this research was to quantify the effects of land-use/land-cover(LU/LC)changes on urban land surface temperature(LST)during a 25-year period(1993–2018)for the semiarid Shiraz City in southern Iran using Landsat data(TM,ETM+,and OLI/TIRS)and machine learning algorithms.Five main LU/LC classes,such as orchard,vegetation,bare surface,asphalt cover,and built-up areas,were identified using a support vector machine algorithm.Landsat images were used to retrieve normalized difference vegetation index(NDVI)and normalized difference built-up index(NDBI).The results showed that the mean LST over the entire study domain increased considerably between 1993 and 2018,due to urbanization,decrease of green areas,and increasing industrial areas.Built-up areas increased considerably by 25.8%from 80 to 100.6 km^(2) between 1993 and 2018,while vegetation cover decreased dramatically by 69.3%.Mean LST increased from 38.4 to 40.2℃ during the 25-year period with a significant increase of 3.9℃ between 2013 and 2018.In addition,the Urban heat island Ratio Index(URI)displayed a substantial upward trend during the 25-year period.

关键词： Urbanization urban heat island land use land cover semiarid population density

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The Interannual Variability of Summer Rainfall in the Arid and semiarid Regions of Northern China and Its Association with the Northern Hemisphere Circumglobal Teleconnection

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Advances in Atmospheric Sciences 2011年第2期28卷 257-268页

作者：黄刚刘永黄荣辉 Key Laboratory of Regional Climate-Environment Research for Temperate East Asia Institute of Atmospheric Physics Chinese Academy of Sciences State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Center for Monsoon System Research Institute of Atmospheric Physics Chinese Academy of Sciences Graduate University of Chinese Academy of Sciences

Using the latest daily observational rainfall datasets for the period 1961–2008, the present study investigates the interannual variability of June–September （JJAS） mean rainfall in northern China. The regional characteristics of JJAS mean rainfall are revealed by a rotated empirical orthogonal function （REOF） analysis. The analysis identifies three regions of large interannual variability of JJAS rainfall： North China （NC）, Northeast China （NEC）, and the Taklimakan Desert in Northwest China （TDNWC）. Summer rainfall over NC is shown to have displayed a remarkable dry period from the late 1990s; while over NEC, decadal-scale variation with a significant decreasing trend in the last two decades is found, and over TDNWC, evidence of large interannual variability is revealed. Results also show that the interannual variability of JJAS rainfall in northern China is closely associated with the Northern Hemisphere circumglobal teleconnection （CGT）. Correlation coefficients between the CGT index and regional-averaged JJAS mean rainfall over NC and NEC were calculated, revealing values of up to 0.50 and 0.53, respectively, both of which exceeded the 99% confidence level.

关键词： rotated empirical orthogonal function analysis arid semiarid interannual variability circumglobal teleconnection

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Estimating leaf area index by inversion of reflectance model for semiarid natural grasslands

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Science China Earth Sciences 2009年第1期52卷 66-84页

作者： ZHANG Na ZHAO YingShi College of Resources and Environment Graduate University of Chinese Academy of SciencesBeijing 100049China

The study developed an integrated reflectance model combining radiative transfer and geometric optical properties in order to inverse leaf area index(LAI) of semiarid natural grasslands.In order to better link remote sensing information with land plants,and facilitate regional and global climate change studies,the model introduced a simple but important geometrical similarity parameter related to plant crown shapes.The model revealed the influences of different plant crown shapes(such as spherical,cylindrical/cuboidal and conic crowns) on leaf/branch angle distribution frequencies,shadow ground coverage,shadowed or sunlit background fractions,canopy reflectance,and scene reflectance.The modeled reflectance data agreed with the measured ones in the three Leymus chinensis steppes with different degradation degrees,which validated the reflectance model.The lower the degradation degree was,the better the modeled data agreed with the measured data.After this reflectance model was coupled with the optimization inversion method,LAI over the entire study region was estimated once every eight days using the eight-day products of surface reflectance obtained by multi-spectral Moderate-Resolution Imaging Spectroradiometer(MODIS) during the growing seasons in 2002.The temporal and spatial patterns of inversed LAI for the steppes with different cover degrees,swamps,flood plains,and croplands agreed with the general laws and measurements very well.But for unused land cover types(sands,saline,and barren lands) and forestlands,totally accounting for about 10% of the study region,the reasonable LAI values were not derived by inversing,requiring further revising of the model or the development of a new model for them.

关键词： leaf area index plant crown shape geometrical similarity parameter reflectance model radiative transfer geometric optics inversion semiarid natural grassland

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ISSUES CONCERNING THE MANAGEMENT AND THE DEVELOPMENT OF ARID AND semiarid LAND IN CHINA

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干旱区资源与环境 1993年第Z1期7卷 406-411页

作者： Wang Jiuwen Institute of Desert Control, Inner Mongolia Forestry College, Hohhot 010019

The arid and semiarid land in China covers a vast area, about 3.5 million km^2(not coun-ting the Tibet Plateau),where natural resources are very aboundant. In this area, the totalsolar radiation is as high as 140--160 kilocalorie / cm^2. a. There are about 167 million ha ofvarious grasslands, accounting for nearly 60% of the national grassland area.

关键词： Arid and semiarid Land Environmental Management Resources Development

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Species richness and similarity of the flora on four lajedos in Boa Nova, Bahia, Brazil

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Journal of Mountain Science 2023年第6期20卷 1526-1539页

作者： Morgana Maria DO CARMO BARBOSA Anderson FERREIRA PINTO MACHADO Andrea Karla ALMEIDA DOS SANTOS Raymundo JoséDE Sá-NETO Michele MARTINS CORRêA Graduate Program in Environmental Sciences State University of Southwest BahiaUniversity Campus“Juvino Oliveira”BR 415km 0445700-000ItapetingaBahiaBrazil Secretary of Education of the State of Bahia Military Police College Eraldo TinocoBrasilia Avenue273Kadija45650-120Vitoria da ConquistaBahiaBrazil Mongoyós Herbarium Multidisciplinary Institute in HealthCampus Anísio TeixeiraFederal University of BahiaRua Hormindo Barros58Bairro Candeias45029-094Vitoria da ConquistaBahiaBrazil Department of Natural Sciences State University of Southwest BahiaEstrada do Bem Querers/nBairro Candeias45083-900Vitoria da ConquistaBahiaBrazil

The municipality of Boa Nova,in northeastern Brazil,is in an ecotone zone between the Caatinga and Atlantic Forest phytogeographic domains.The transition phytophysiognomy is seasonal forest and known locally as mata de cipó.In these phytophysiognomies there are lajedos,which are rock outcrops colonized by vegetation welladapted to extreme microclimatic variation and vegetation diversity is affected by the vegetation types of the surrounding areas.Due to the singularity of these environments and the relevance of floristic studies for conservation,this work aimed to identify the species richness and compare the similarity of the flora on four rock outcrops in Boa Nova.The flora was surveyed during exploratory walks along lajedos between 2016 and 2019.In total,162 species were identified on the Boa Nova outcrops.The flora has a composition and structure similar to semiarid outcrops,as well as endemic species that also occur in surrounding phytophysiomies.Despite the proximity,a similarity index revealed there is floristic dissimilarity between the areas.Nine new occurrences were recorded for the region,five species are threatened with extinction(Aosa gilgiana,Ficus cyclophylla,Hippeastrum stigmovittatum,Pleroma caatingae and Trixis pruskii),and 43 species are common in anthropogenic areas.This reinforces the importance of actions to conserve these areas.

关键词： Ecotone Flora Inselberg Rock outcrops semiarid Similarity

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Evaluation of Eleven Reference Evapotranspiration Models in semiarid Conditions

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Journal of Water Resource and Protection 2017年第12期9卷 1469-1490页

作者： Koffi Djaman Komlan Koudahe Christopher Oluwakunmi Akinbile Suat Irmak Department of Plant and Environmental Sciences New Mexico State University Agricultural Science Center at Farmington Farmington USA ADA Consulting Africa Lome Togo Department of Agricultural & Environmental Engineering Federal University of Technology Akure Nigeria Department of Biological Systems Engineering University of Nebraska-Lincoln Lincoln USA

The objectives of this study were to evaluate the performance of the FAO Penman Monteith reference evapotranspiration model under limited data and some mine temperature methods of reference evapotranspiration (ETo) under the semiarid and arid conditions in Mali. The results showed that under limited data conditions, the FAO-PM equation achieved accurate estimation of daily ETo when solar radiation, relative humidity, and wind speed are lacking individually with root mean squared errors (RMSE) averaging 0.52, 0.56 and 0.62 mm/day, respectively. Much more accurate ETo was estimated under relative humidity and wind speed missing data conditions with RMSE varying from 0.20 to 0.58 mm/day and average RE, MBE and MAE of 6.7%, -0.25 mm/day and 0.30 mm/day. The Jensen-Haise equation systematically overestimated ETo while the Hansen, Christiansen, and Irmak, and the two Tabari’s equations underestimated ETo at all weather stations. The Abtew equation showed the best performance among the selected ETo equations.

关键词： Reference Evapotranspiration semiarid and Arid Climate Mali

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Climate Change, Adaptive Strategies and Rural Livelihoods in semiarid Tanzania

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Natural Resources 2013年第3期4卷 266-278页

作者： Richard Y. M. Kangalawe James G. Lyimo Institute of Resource Assessment University of Dar es Salaam Dar es Salaam Tanzania Institute of Resource Assessment University of Dar es Salaam Dar es Salaam Tanzania.

Climate change is a global challenge to both sustainable livelihoods and economic development. In Tanzania as in most African countries, farming depends almost entirely on rainfall, a situation that makes agriculture and thus rural livelihoods especially in semiarid environments particularly vulnerable to climate change. This study analyses the impacts of climate change and variability on rural livelihoods with particular focus on agricultural production, food security and adaptive capacities in semiarid areas of Tanzania. The methods used in this study included focus group discussions, key informant interviews, household surveys and field observations. Results from the study indicate that communities understood climate change in terms of variability in rainfall patterns and amount, temperature patterns, wind, water availability, increased incidences of drought and decreased agricultural productivity. Communities in the study area acknowledged that while rainfall amounts have decreased over the last thirty years, temperatures have increased;an experience is also supported by meteorological data. Such changes were claimed to have reduced agricultural productivity particularly due to prolonged drought, inadequate and uneven distribution of rainfall as well as unpredictable onset and ending of rains. Stressors such as crop diseases and pests, low soil fertility and inadequate extension services were also reported to contribute to the decline in agricultural productivity and re-occurrence of food insecurity. In response, communities have developed multiple adaptation strategies, including growing of drought tolerant and early maturing crop varieties, increasing wetlands cultivation, water harvesting for small-scale irrigation and livestock keeping. However, households with limited livelihood assets are more vulnerable to the impacts of climate change and food insecurity. The study argues that diversification of adaptive strategies, such as water harvesting for small-scale irrigation, integration of livestock and crop

关键词： Climate Change Adaptive Strategies Food Insecurity Rural Livelihoods semiarid Tanzania

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Evapotranspiration, Grain Yield, and Water Productivity of Spring Oat (Avena sativa L.) under semiarid Climate

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Agricultural Sciences 2018年第9期9卷 1188-1204页

作者： Koffi Djaman Michael O’Neill Curtis Owen Komlan Koudahe Kevin Lombard Department of Plant and Environmental Sciences New Mexico State University Agricultural Science Center at Farmington Farmington NM USA ADA Consulting Africa Lomé Togo

Spring oat (Avena sativa) is produced for grain, hay, and green manure and can be integrated into a cropping system as a cover crop. Twenty-eight oat genotypes (G1, G2, G3, …., G28), selected for their adaptability to the Southwestern United States, were evaluated for their yield performance under sprinkler irrigation during four growing seasons (2005-2008) at the Agricultural Science Center at Farmington, New Mexico State University. The genotypes were arranged in randomized complete blocs design with four replications. Irrigation scheduling was based on evapotranspiration and the depletion criterion of 40% to 45% total available water (TAW) was practiced to prevent the plants from experiencing any water stress. Crop evapotranspiration estimated by the FAO crop coefficient and reference evapotranspiration approach was low about 2 mm/day during crop initial stage and increased with plant growth and reached the maximum during crop mid-season or reproductive stage. It decreased during crop late season. Daily crop evapotranspiration varied from 0.5 to 12.6 mm in 2008 and the seasonal Spring oat evapotranspiration varied from 535.8 to 591 mm. Averaged across the four growing seasons, oat evapotranspiration was 570.4 mm. The results showed that Spring oat plant height varied significantly with genotypes and ranged from 59.1 to 100.8 cm. Oat grain yield significantly varied with years and genotypes. Grain yield varied from 3386 to 6498 kg/ha and average yield was 4245, 4265, 5477, and 4025 kg/ha during the 2005, 2006, 2007 and 2008, respectively. The best performing genotypes were G1, G2, G7, G19, G20, G21 and G23 with average yield greater than 4800 kg/ha while G3, G13, G17 and G27 showed the lowest yield among the genotypes. Oat crop water use efficiency (CWUE) varied with genotype and years and ranged from 0.53 to 1.07 kg/m3 and averaged 0.65, 0.78, 0.91 and 0.70 kg/m3 in 2005, 2006, 2007 and 2008, respectively. The highest CWUE was achieved by G19 and the lowest CWUE was obtained by G13. Irrigation water use effici

关键词： Spring Oat Genotypes Evaluation Grain Yield Water Productivity High Elevation semiarid Climate

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Water catchment with native species in the Brazilian semiarid

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Agricultural Sciences 2014年第2期5卷 152-156页

作者： Joao Vianey Fernandes Pimentel Hugo Orlando Carvallo Guerra Francisco Jardel Rodrigues da Paixao Luciano F.Marques Leandro do Vale Francisca N.Brito Agroecology and Environment of Federal Institute of Education Science and Technology of Rio Grande do Norte(UFRN) QuixeramobimBrazil Agricultural Engineering Department of Graduate Agricultural EngineeringFederal University of Campina Grande(DEAG/UFCG)Campina GrandeBrazil Technological Axis Natural Resources Centec Institute/Fatec Sertao Central QuixeramobimBrazil State University of Maranhao(UEMA) BalsasBrazil Agribusiness Centec Institute/FATEC Sertao Central Undergraduate Scholarship Foundation Protection Research of CearáFUNCAPQuixeramobimBrazil

Xerophyticplants are well adapted to the semiarid conditions because they have a high potential for the use of rainwater. They can store it in their roots (xylopodiums). The Amburanacearensis, commonly called Cumaru, native of the Brazilian semiarid, is very important because of its multiple-use: good quality wood, active food ingredient, perfume and medicine production. However, its management is practically unknown. Aiming to know more about this culture, an experiment was conducted to quantify the Cumaruwater needs, evaluate its water-use efficiency and the capacity of roots to store water. Five levels of water (0%, 25%, 50%, 75% and 100% of evapotranspiration) and five-plant spacing (0.20 × 0.20 m, 0.20 × 0.10 m, 0.20 × 0.05 m, 0.10 × 0.10 m and 0.05 × 0.05 m) were tested, and the results obtained analyzed statistically throughout F test. No influence of soil water level and plant spacing in the moisture content of the whole plant, in the aerial part or in the xylopodiums was observed. However, there was an effect of the treatments on the water stored in the whole plant in the aerial part or in the roots, per unit area. More than 80% of the water was stored in the roots. The crop growing with the smaller spacing without irrigation was shown to be quite efficient in using the rainwater, compared with traditional cultures irrigated.

关键词： Xerophytic Xylopodium semiarid Water Use Efficient

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