The authors have declared that no competing interests exist.
Conceived and designed the experiments: JPL JFL WX. Performed the experiments: JPL JFL DX PW LP. Analyzed the data: JPL JFL MHL. Contributed reagents/materials/analysis tools: JPL WX JFL YJ. Wrote the paper: JPL JFL MHL.
Forest tree species distributed across a wide range of geographical areas are subjected to differential climatic and edaphic conditions and long-term selection, leading to genotypes with morphological and physiological adaptation to the local environment. To test the ability of species to cope with changing environmental conditions, we studied the ecophysiological features of
The global average temperature has increased by approximately 0.6°C (±0.2°C) over the past 100 years and is projected to continue to rise at a rapid rate
Many studies have documented geographic variations in morphology
Nitrogen and phosphorus play vital roles in plant functioning, and are among the most important limiting nutrients in terrestrial ecosystems
Studies indicated that mobile carbohydrate concentration of trees increased with elevation during the growing season
We studied the ecophysiological characteristics of
The present study included an
Elevation m a.s.l. | Slope exposure | MAT (°C) | MAP (mm) | Soil Type | Community | |
|
||||||
Northern distribution (ND) | 256 | SE | 7.7 | 819.6 | Brown soil |
|
Mid-distribution (MD) | 935 | SW | 13.2 | 1529.4 | Yellow brown soil |
|
Southern distribution (SD) | 1895 | SE | 14.9 | 985.8 | Red soil |
|
|
||||||
Common garden (WH) | 870 | SE | 17.5 | 1100.0 | Yellow brown soil |
MAT = mean annual temperature; MAP = mean annual precipitation; ND = northern distribution, Zhuang-He in NE China, MD = middle distribution, He-Feng in central China, SD = southern distribution, An-Ning in SW China. WH = Wu-Han in Hubei province, central China.
Samples were taken between August 20 and 28, 2010 (i.e. 2 years after transplanting). Samplings were carried out around noon to minimize the influences of sunlight and temperature on carbohydrate concentration. Each seedling sampled was completely excavated. Leaves (second flush leaves), stem wood (with bark), and fine roots (<0.5 cm in diameter, with bark) were separately collected. A 2-cm long stem segment was taken from the middle part of each stem. Root samples were carefully washed. To obtain a single sample for each tissue for each stand, we mixed the same tissue collected from 5–6 seedlings grown in 3–5 gaps within each stand (
We randomly selected 3 out of the 5
Photosynthetic photon flux density (PPFD) response curves were made with a portable infrared gas analyzer (Licor 6400, Li-Cor, Lincoln, NE). The assimilation rates were measured on fully expanded leaves from 09:00 to 12:00 h on clear, cloudless days (15–30, August, 2010). The air cuvette temperature, the relative humidity, and the air CO2 concentration were maintained at 25±2°C, 50±5%, and 400 µL L−1, respectively. PPFD was decreased from 2000 to 0 µmol m−2 s−1 (2000, 1800, 1600, 1400, 1200, 1000, 800, 600, 400, 200, 100, 80, 50, 20, 0 µmol m−2 s−1). Assimilation was recorded at each light level following a 5 min acclimation time, and three replications were used for each plant. According to Prioul and Chartier
The powdered material (0.1 g) was put into a 10 ml centrifuge tube, where 5 ml of 80% ethanol was added. The mixture was incubated at 80°C in a water bath shaker for 30 min, and then centrifuged at 4000 rpm for 5 min. The pellets were extracted two more times with 80% ethanol. Supernatants were retained, combined and stored at −20°C for soluble sugar determinations. The ethanol-insoluble pellet was used for starch extraction. Glucose was used as a standard. Soluble sugars were determined using the anthrone method
The finely ground plant samples were firstly digested through the Kjeldahl procedure, using H2SO4 and H2O2 for digestion, and then the total nitrogen and phosphorus concentrations were determined using the flow injection method, and potassium was determined by applying the flame photometry method
NSC is defined as the sum of the starch plus the total soluble sugars for each sample. Data (NSC, starch, total soluble sugars, and nutrient concentration) were confirmed for normality by Kolmogorov-Smirnov-Tests. Two-way analysis of variance (ANOVA) was performed for each parameter within each tissue type, using experiments (
Seedlings grown in ND had significantly higher tissue N concentration than those grown in MD and SD (p<0.05,
Nutrients | Tissues | ND | MD | SD |
|
||||
N | Leaves | 17.17±0.53a | 13.16±0.90b | 12.36±1.39b |
Stem | 5.58±0.51a | 4.02±0.52b | 2.82±0.32c | |
Roots | 7.46±0.83a | 3.25±0.37b | 2.59±0.75b | |
P | Leaves | 1.47±0.37a | 1.10±0.23a | 1.61±0.18a |
Stem | 0.63±0.07a | 0.71±0.11 a | 0.82±0.07a | |
Roots | 0.71±0.14 a | 0.77±0.58a | 1.10±0.21a | |
K | Leaves | 7.38±0.56a | 6.72±1.02a | 6.27±0.29a |
Stem | 3.23±0.19a | 3.84±0.65a | 3.94±0.42a | |
Roots | 5.09±0.41a | 3.28±0.40b | 5.27±0.79a | |
|
||||
N | Leaves | 14.56±1.36a | 13.35±1.87a | 13.71±0.71a |
Stem | 3.40±0.13a | 3.74±0.33a | 3.22±0.48a | |
Roots | 5.47±0.62a | 6.07±2.87a | 5.19±0.49a | |
P | Leaves | 0.82±0.08a | 0.83±0.16a | 0.97±0.09a |
Stem | 0.31±0.04a | 0.36±0.07a | 0.68±0.21a | |
Roots | 0.48±0.05a | 0.53±0.32a | 1.67±0.62a | |
K | Leaves | 6.35±2.09a | 6.66±1.82a | 6.96±0.47a |
Stem | 2.41±0.71a | 3.13±1.23a | 4.51±0.72a | |
Roots | 3.19±0.76a | 4.65±1.53a | 4.42±0 .93a |
Different letters indicate significant difference at p<0.05 level for each row, tested using Duncan's multiple range test. ND = northern distribution, Zhuang-He in NE China, MD = middle distribution, He-Feng in central China, SD = southern distribution, An-Ning in SW China.
No difference was found in N, P, and K concentration in seedlings grown in the common garden for 2 years after transplanting from different geographical locations (
Seedlings grown in ND, MD and ND showed non-significant difference in AQE (
AQE | Amax | Rd | LCP | LSP | |
|
|||||
ND | 0.0591±0.0442a | 5.2342±1.1017b | 2.3938±0.036a | 66.1±25.8ab | 293.6±78.1a |
MD | 0.0205±0.0051a | 2.5616±1.1463b | 0.8901±0.2748b | 87.6±4.3a | 392.8±35.6a |
SD | 0.0679±0.0264a | 13.1006±2.0737a | 1.7349±0.8356ab | 29.4±13.3b | 504.4±181.4a |
|
|||||
ND | 0.0338±0.0075a | 14.899±0.2402ab | 1.6267±0.0756a | 61.3±1.5a | 637.9±15.3a |
MD | 0.0353±0.0084a | 14.5339±3.2761b | 1.8476±0.3845a | 68.6±15.1a | 659.1±49.9a |
SD | 0.0443±0.0104a | 19.7417±0.7429a | 1.9094±0.3087a | 53.8±2.6a | 714.4±59.7a |
ND = northern distribution, Zhuang-He in NE China , MD = middle distribution, He-Feng in central China, SD = southern distribution, An-Ning in SW China; AQE, apparent quantum efficiency, µmol CO2/µmol photons; Amax, maximum photosynthetic rates, µmol m−2 s−1; Rd, dark respiration, µmol m−2 s−1; LCP, light compensation point, µmol m−2 s−1; LSP, light saturation point, µmol m−2 s−1. Different letters indicate significant difference at p<0.05 level for each parameter among the three locations within each experiment (i.e.
Like plants grown
Concentration of soluble sugars in stems of SD plants were much less than those in ND and MD plants (p<0.05,
|
|
|||||||
df | F |
|
Effects | df | F |
|
Effects | |
|
||||||||
Leaves | 4 | 3.605 | 0.094 | No effects | 4 | 4.392 | 0.067 | No effects |
Stem | 4 | 12.158 | 0.008 | ND≈MD>SD | 4 | 0.906 | 0.453 | No effects |
Roots | 4 | 5.642 | 0.042 | SD≈ND>MD | 4 | 0.619 | 0.570 | No effects |
|
||||||||
Leaves | 4 | 79.144 | 0.000 | ND>MD≈SD | 4 | 18.673 | 0.003 | ND≈MD>SD |
Stem | 4 | 1.107 | 0.390 | No effects | 4 | 0.346 | 0.720 | No effects |
Roots | 4 | 34.153 | 0.001 | ND>MD≈SD | 4 | 3.631 | 0.093 | No effects |
|
||||||||
Leaves | 4 | 1.151 | 0.378 | No effects | 4 | 0.019 | 0.981 | No effects |
Stem | 4 | 7.258 | 0.025 | ND>MD≈SD | 4 | 0.792 | 0.495 | No effects |
Roots | 4 | 7.441 | 0.024 | ND>MD≈SD | 4 | 1.012 | 0.418 | No effects |
ND = northern distribution, Zhuang-He in NE China, MD = middle distribution, He-Feng in central China, SD = southern distribution, An-Ning in SW China.
Two years after transplanting seedlings into the common garden, concentration of mobile carbohydrates in tissues did not differ among plants originating from ND, MD, and SD (
Only P allocation to roots and K allocation to leaves differed significantly among ND, MD, and SD plants grown
|
|
|||||
ND | MD | SD | ND | MD | SD | |
|
||||||
Leaves | 0.35±0.06 | 0.35±0.09 | 0.38±0.07 | 0.36±0.02 | 0.30±0.06 | 0.40±0.10 |
Stem | 0.22±0.03 | 0.20±0.13 | 0.18±0.06 | 0.23±0.03a | 0.18±0.06ab | 0.13±0.01b |
Roots | 0.43±0.07 | 0.45±0.06 | 0.44±0.11 | 0.41±0.05 | 0.52±0.11 | 0.48±0.11 |
|
||||||
Leaves | 0.31±0.09 | 0.21±0.10 | 0.17±0.04 | 0.26±0.01a | 0.24±0.07a | 0.14±0.03b |
Stem | 0.26±0.05 | 0.20±0.05 | 0.18±0.06 | 0.28±0.05a | 0.21±0.05ab | 0.13±0.02b |
Roots | 0.43±0.10b | 0.59±0.06ab | 0.65±0.10a | 0.46±0.06b | 0.55±0.12ab | 0.73±0.06a |
|
||||||
Leaves | 0.26±0.05a | 0.21±0.04ab | 0.15±0.02b | 0.28±0.03 | 0.22±0.03 | 0.26±0.07 |
Stem | 0.22±0.03 | 0.23±0.18 | 0.18±0.05 | 0.30±0.10 | 0.20±0.01 | 0.23±0.02 |
Roots | 0.51±0.07 | 0.55±0.14 | 0.67±0.07 | 0.42±0.08b | 0.58±0.04a | 0.51±0.08ab |
|
||||||
Leaves | 0.16±0.03 | 0.15±0.02 | 0.12±0.05 | 0.17±0.05 | 0.14±0.02 | 0.22±0.09 |
Stem | 0.24±0.03a | 0.15±0.10ab | 0.10±0.03b | 0.26±0.03a | 0.15±0.05b | 0.13±0.01b |
Roots | 0.60±0.06b | 0.70±0.08ab | 0.78±0.07a | 0.57±0.08 | 0.71±0.05 | 0.64±0.10 |
|
||||||
Leaves | 0.09±0.02a | 0.03±0.01b | 0.04±0.02b | 0.15±0.07 | 0.16±0.03 | 0.08±0.05 |
Stem | 0.19±0.02 | 0.14±0.09 | 0.20±0.02 | 0.12±0.01a | 0.08±0.02b | 0.09±0.03ab |
Roots | 0.72±0.03 | 0.83±0.09 | 0.76±0.03 | 0.73±0.06 | 0.77±0.04 | 0.82±0.02 |
|
||||||
Leaves | 0.15±0.03 | 0.13±0.01 | 0.11±0.04 | 0.17±0.05 | 0.15±0.02 | 0.21±0.09 |
Stem | 0.23±0.02a | 0.15±0.10ab | 0.11±0.02b | 0.24±0.02a | 0.13±0.04b | 0.13±0.01b |
Roots | 0.62±0.05b | 0.72±0.08ab | 0.78±0.07a | 0.60±0.08 | 0.72±0.04 | 0.67±0.09 |
ND = northern distribution, Zhuang-He in NE China; MD = middle distribution, He-Feng in central China; SD = southern distribution; An-Ning in SW China; No letters indicate non-significant difference, and different letters indicate significant difference at p<0.05 level for each parameter in each tissue type among the three locations within each experiment (i.e.
Plants originating from the north tended to allocate more N and P to stem, as well as more P to leaves, but less P and K to roots compared to plants originating from the south (
Soils in the 3 populations
Different letters indicate significant difference (p<0.05) within each parameter among the three locations.
Geographic locations significantly affected N but not P and K concentration in
Different
Patterns of nutrient allocation did not differ among ND, MD, and SD
Previous studies indicated that leaf N increased with increasing latitude as a result of decreasing mean annual temperature
No differences in leaf dark respiration were found in different provenances of
More than 60% of the mobile carbohydrates (sugars, starch, NSC) were invested into roots, and south plants allocated more carbohydrates to roots than north plants did (
The lack of clear relationships between plant physiological parameters and soil nutrients across scales found in the present study may suggest that climate discrepancy is the major contributor to the differences in physiology of
Today's plant communities are the result of long-term adaptation to their growth environment including climatic impacts. Plant distribution is largely determined by climatic conditions
We thank Dr. Yongyu Sun and Dr. Fangyan Liu for help with sampling in SD.