Sensitivity of ring growth and carbon allocation to climatic variation vary within ponderosa pine trees

Abstract

Most dendrochronological studies focus on cores sampled from standard positions (main stem, breast height), yet vertical gradients in hydraulic constraints and priorities for carbon allocation may contribute to different growth sensitivities with position. Using cores taken from five positions (coarse roots, breast height, base of live crown, mid-crown branch and treetop), we investigated how radial growth sensitivity to climate over the period of 1895-2008 varies by position within 36 large ponderosa pines (Pinus ponderosa Dougl.) in northern Arizona. The climate parameters investigated were Palmer Drought Severity Index, water year and monsoon precipitation, maximum annual temperature, minimum annual temperature and average annual temperature. For each study tree, we generated Pearson correlation coefficients between ring width indices from each position and six climate parameters. We also investigated whether the number of missing rings differed among positions and bole heights. We found that tree density did not significantly influence climatic sensitivity to any of the climate parameters investigated at any of the sample positions. Results from three types of analyses suggest that climatic sensitivity of tree growth varied with position height: (i) correlations of radial growth and climate variables consistently increased with height; (ii) model strength based on Akaike's information criterion increased with height, where treetop growth consistently had the highest sensitivity and coarse roots the lowest sensitivity to each climatic parameter; and (iii) the correlation between bole ring width indices decreased with distance between positions. We speculate that increased sensitivity to climate at higher positions is related to hydraulic limitation because higher positions experience greater xylem tensions due to gravitational effects that render these positions more sensitive to climatic stresses. The low sensitivity of root growth to all climatic variables measured suggests that tree carbon allocation to coarse roots is independent of annual climate variability. The greater number of missing rings in branches highlights the fact that canopy development is a low priority for carbon allocation during poor growing conditions.

The Influence of Monsoon Climate on Latewood Growth of Southwestern Ponderosa Pine

“…For each climate parameter, we investigated both monthly values and a monsoon season average value. Using time (July, August, September, monsoon) and climate parameters (VPD, PDSI, precipitation) as model effects, we performed two-way analyses of variance (ANOVA) on r values (dependent variable) with Tukey's Honestly Significant Difference (HSD) orthogonal contrast post hoc tests [50]. Levine and Bartlett tests were used to test the assumption of homogeneous variance.…”

“…In each tree, we collected cores from two treetop radii for a total of 72 cores. Treetops were used because they are the most climatically sensitive position; the methodology for core preparation and analysis has been previously described [50]. Treetop latewood chronology statistics from COFECHA [51] and ARSTAN [52] include: sample size = 27 trees, mean annual growth = 0.25 mm, mean sensitivity = 0.49, series intercorrelation = 0.45, first order autocorrelation = 0.43, and expressed population signal [53] = 0.96.…”

“…As removal of three large-diameter cores would likely damage treetops, we cored at breast height for this portion of our study. These 30 cores were prepared using standard dendrochronological techniques [50].…”

Prediction of the carbon pool for lacebark pine under future temperature changes

“…Standard chronology (STD) and residual chronology (RES) were established ( Table 1). The mean sensitivities of STD and RES remain between 0.15 and 0.17, both being at an acceptable level (Kerhoulas and Jeffrey 2011). The STD chronologies are obviously better than those of RES; therefore lacebark pine STD in the study area can better reflect the impact of climatic change on tree-ring growth.…”

Radial Growth Behavior of Pines on Romanian Degraded Lands

“…At the far end, the average series was truncated at the depth of at least 3 trees [78]. The average series was converted by standardization in series of indices, performed again on WinDENDRO, where the smoothing filter was the spline curve and for which the value of −4 of the Lagrange parameter was chosen [79].…”