Explore the vast range of titles available.

Tree radial growth can have significantly different responses to climate change depending on the environment. To elucidate the effects of climate on radial growth and stable carbon isotope ([delta].sup.13C) fractionation of Qinghai spruce (Picea crassifolia), a widely distributed native conifer in northwestern China in different environments, we developed chronologies for tree-ring widths and [delta].sup.13C in trees on the southern and northern slopes of the Qilian Mountains, and analysed the relationship between these tree-ring variables and major climatic factors. Tree-ring widths were strongly influenced by climatic factors early in the growing season, and the radial growth in trees on the northern slopes was more sensitive to climate than in trees on the southern. Tree-ring [delta].sup.13C was more sensitive to climate than radial growth. [delta].sup.13C fractionation was mainly influenced by summer temperature and precipitation early in the growing season. Stomatal conductance more strongly limited stable carbon isotope fractionation in tree rings than photosynthetic rate did. The response between tree rings and climate in mountains gradually weakened as climate warmed. Changes in radial growth and stable carbon isotope fractionation of P. crassifolia in response to climate in the Qilian Mountains may be further complicated by continued climate change.

Tree ring chronologies (tree ring width—TRW, earlywood—EW, latewood—LW) were constructed to investigate fir’s (Abies borisii-regis Mattf.) response to key hydrometeorological factors, namely precipitation, temperature and drought (12-month Standardized Precipitation Evapotranspiration Index, SPEI-12). There has been only one previously published study conducted in the northern area of the species’ expansion (Albania). The current study was conducted in the southern area of the species’ expansion (Central Greece). Precipitation was the most important factor that affected tree growth. May precipitation was positively correlated with LW, while June and July precipitation was positively correlated with both EW and LW. Previous September precipitation was positively correlated with EW and LW. Interestingly, the current September precipitation was negatively correlated with EW. High temperatures in April showed a positive relation with LW, high temperatures in June negatively affected all chronologies, while high temperatures July and August were negatively related with LW. High autumn temperatures in the previous year significantly (negatively) influenced all tree ring chronologies. The SPEI index revealed that wet conditions during May and June positively correlated with high tree growth for both EW and LW, while wet conditions in July and August significantly affect LW formation. Wet conditions in the previous September also had a positive effect on tree growth. SPEI showed similar behavior with precipitation, showing that precipitation is the driving factor in fir growth. The results highlight the importance of summer rainfall and temperature in controlling tree growth in Mediterranean regions. The study revealed significant knowledge on the susceptibility of Abies borisii-regis Mattf. to climate variability and highlighted its consequences for future forest management plans.

We present a reconstruction of July--August mean maximum temperature variability for northern West Sichuan Plateau (NWSP), China based on a chronology of tree-ring widths over the period 1646--2013 AD. A regression model explains 37.1 % of the variance of July--August mean maximum temperature during the calibration period from 1954 to 2012. Seven major cold periods were identified including 1708--1711, 1765--1769, 1818--1821, 1824--1828, 1832--1836, 1839--1842 and 1869-1877, and three major warm periods occurred between 1655-1668, 1719--1730 and 1858--1859 in our reconstruction. Comparison with other nearby temperature reconstructions and spatial correlations with gridded land surface temperature dates revealed that our temperature reconstruction has high spatial representativeness. 20th century rapid warming wasn’t obvious in the NWSP mean maximum temperature reconstruction, which implied that mean maximum temperature might play an important and different role in global change as unique temperature indicators. Multi-taper method (MTM) spectral analysis revealed significant periodicities of 170-, 49--114-, 25--32-, 5.7-, 4.6--4.7-, 3.0--3.1-, 2.5- and 2.1--2.3-year quasi-cycles at a 95 % confidence level. The mean maxi mum temperature variability in northwest Sichuan may be affected by ENSO, PDO, AMO and solar activity.

Abstract The jaboticaba tree (Plinia peruviana (Poir.) Govaerts) is a native Brazilian species, and its fruits are very popular in Brazil. The purpose of this study was to model the diameter growth, and determine the age of jaboticaba trees in four natural populations in Southwest of Paraná State, Brazil. The knowledge of the growth dynamics of this species is essential to assist management and conservation strategies and to discover when this species was established in the region. Core samples were collected to obtain complete growth series by measurement of annual growth rings. The series were crossdated, seven growth models were adjusted, and the best model for each site and a general model were selected using statistics rules. The time series spanned periods of ~75 to ~100 years, and growth ranged between 0.27 and 0.37 cm year-1. Chapman-Richards’ model showed better adherence for locations individually, and Monomolecular when grouped. Because to the age reached by the jaboticaba trees and the high density of this species in these natural populations, consequently named “jaboticabais”, it was inferred that there was an anthropogenic action in the dispersion and formation of the settlements through the indigenous and caboclos that inhabited the region before 1940. Also, this is the first work to register and verify the fusion of trunks for species of the Plinia genus using double piths found in samples, a feature that must be considered to avoid overestimating the age of jaboticaba trees based solely on measuring tree diameter. Resumo A jabuticabeira (Plinia peruviana (Poir.) Govaerts) é uma espécie nativa brasileira e seus frutos são muito populares no Brasil. O objetivo deste estudo foi modelar o crescimento diamétrico e determinar a idade de jabuticabeiras em quatro populações naturais no Sudoeste do Paraná, Brasil. O conhecimento da dinâmica de crescimento desta espécie é essencial para auxiliar na definição de estratégias de manejo e conservação e descobrir quando esta espécie se estabeleceu na região. Amostras do tronco foram coletadas para obter séries completas de crescimento através da medição dos anéis de crescimento anuais. As séries foram cruzadas, sete modelos de crescimento foram ajustados e o melhor modelo para cada site e um modelo geral foram selecionados usando regras estatísticas. A série temporal abrangeu períodos de ~75 a ~100 anos, e o crescimento variou entre 0,27 e 0,37 cm ano-1. O modelo de Chapman-Richards apresentou melhor aderência para locais individualmente, e o modelo Monomolecular quando agrupados. Devido à idade atingida pelas jabuticabeiras e à alta densidade desta espécie nessas populações naturais, consequentemente denominadas “jaboticabais”, inferiu-se que houve uma ação antrópica na dispersão e formação destas populações através dos indígenas e caboclos que habitavam a região antes de 1940. Além disso, este é o primeiro trabalho a registrar a fusão de troncos de espécies do gênero Plinia, encontrando medulas duplas em amostras, característica que deve ser considerada para evitar superestimar a idade das jabuticabeiras com base apenas na medição do diâmetro da árvore.