Walking Response of the Mediterranean Pine Engraver, Orthotomicus erosus, to Novel Plant Odors in a Laboratory Olfactometer

The Lusitanian pine vole ( Microtus lusitanicus (Gerbe, 1879)) and the Mediterranean pine vole ( Microtus duodecimcostatus de Selys-Longchamps, 1839) are sister species with burrowing habits and a restricted European distribution. Our aim was to assess the relative effect of environmental, soil, and spatial characteristics on the distribution of these species in Portugal, and obtain predicted occurrence maps for each species, particularly to identify areas of sympatry. We used spatial eigenvector mapping (SEVM) to describe the spatial autocorrelation in species data, and we partitioned the variance in species distributions to quantify the relative effects of environmental, soil, and spatial characteristics. The spatial variables explained the major part of variability in both species distributions and were more important than environmental or soil variables. The Lusitanian pine vole occurs in areas outside landscape units of grassland, higher rainfall, frost, and cambisols, with mostly acid soils, lower abundance of litosols, and presence of solonshaks. The Mediterranean pine vole is distributed in grassland areas within intermediate values of soil pH, dominated by litosols and luvisols, and lower rainfall, frost, and cambisols. Our results showed disjunct sympatric areas of small size and a parapatry boundary for the centre of Portugal, suggesting that contact zones are probably narrow.

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How Do Mediterranean Pine Trees Respond to Drought and Precipitation Events along an Elevation Gradient?

Forests ◽

10.3390/f11070758 ◽

2020 ◽

Vol 11 (7) ◽

pp. 758 ◽

Cited By ~ 2

Author(s):

Sonja Szymczak ◽

Martin Häusser ◽

Emilie Garel ◽

Sébastien Santoni ◽

Frédéric Huneau ◽

...

Keyword(s):

Tree Growth ◽

Elevation Gradient ◽

Growth Patterns ◽

Precipitation Event ◽

Cold Environments ◽

Pine Trees ◽

The Mediterranean ◽

Mediterranean Pine ◽

Study Sites ◽

Precipitation Events

Drought is a major factor limiting tree growth and plant vitality. In the Mediterranean region, the length and intensity of drought stress strongly varies with altitude and site conditions. We used electronic dendrometers to analyze the response of two native pine species to drought and precipitation events. The five study sites were located along an elevation gradient on the Mediterranean island of Corsica (France). Positive stem increment in the raw dendrometer measurements was separated into radial stem growth and stem swelling/shrinkage in order to determine which part of the trees’ response to climate signals can be attributed to growth. Precipitation events of at least 5 mm and dry periods of at least seven consecutive days without precipitation were determined over a period of two years. Seasonal dynamics of stem circumference changes were highly variable among the five study sites. At higher elevations, seasonal tree growth showed patterns characteristic for cold environments, while low-elevation sites showed bimodal growth patterns characteristic of drought prone areas. The response to precipitation events was uniform and occurred within the first six hours after the beginning of a precipitation event. The majority of stem circumference increases were caused by radial growth, not by stem swelling due to water uptake. Growth-induced stem circumference increase occurred at three of the five sites even during dry periods, which could be attributed to stored water reserves within the trees or the soils. Trees at sites with soils of low water-holding capacity were most vulnerable to dry periods.

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