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Mean family age of angiosperm tree communities and its climatic correlates along elevational and latitudinal gradients in eastern North America
Author(s) -
Qian Hong,
Zhang Jian,
Hawkins Bradford A.
Publication year - 2018
Publication title -
journal of biogeography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 158
eISSN - 1365-2699
pISSN - 0305-0270
DOI - 10.1111/jbi.13108
Subject(s) - latitude , elevation (ballistics) , seasonality , precipitation , bergmann's rule , environmental science , ecology , climatology , altitude (triangle) , mean radiant temperature , atmospheric sciences , physical geography , geography , environmental gradient , climate change , biology , geology , meteorology , habitat , geometry , mathematics , geodesy
Aim The species comprising local communities are assembled from the species pool of the region where they are located, and environmental filtering influences which species occupy local communities based on their traits. Latitude and elevation generate two major thermal gradients, and temperature minimum and seasonality can drive community assembly, but few studies have tested if community assembly along both latitudinal and elevational gradients within the same region generates similar patterns of assembly. Here, we test hypotheses on the relations of mean family age ( MFA ) of angiosperm trees in local communities with environmental temperature and compare the relations between latitudinal and elevational gradients in eastern North America. Location USA . Method We used correlation and regression analyses and structure equation modelling approach to assess the relation of MFA to elevation, latitude and climatic variables, which included minimum temperature, temperature seasonality, annual precipitation and precipitation seasonality. Results The MFA of a local forest community decreased with increasing latitude and elevation for all gradients examined. For each gradient, the slope of the relationship between MFA and latitude or elevation was steeper for forest communities with larger values of MFA than for those with smaller values of MFA , and the standard deviation of MFA decreased with increasing latitude and elevation. MFA decreased significantly with decreasing minimum temperature for both latitudinal and elevational gradients, but the slope of the relationship between MFA and minimum temperature was steeper for elevational gradients than for latitudinal gradients. Minimum temperature had a much stronger relationship with MFA than temperature seasonality for both latitudinal and elevational gradients. Main conclusions Our results indicate that minimum temperature, rather than temperature seasonality, is a major driver of the pattern of decreasing MFA with increasing latitude and elevation, and the relationship between temperature and MFA is stronger (steeper) for elevational gradients than for latitudinal gradients.