Chinese Pine Trees Research Articles

Habitat Suitability of Pine Wilt Disease in Northeast China under Climate Change Scenario

Pine wilt disease (PWD), caused by Bursaphelenchus xylophilus, is one of the most severe forest diseases worldwide. PWD causes devastating disasters to Chinese pine trees, seriously threatening forestry production and the forest ecological environment, and causes economic losses of over ten billion yuan per year to China. Previous studies have shown that the spread of PWD is closely related to climate factors. Today, PWD is spreading rapidly owing to abnormal climate changes. In order to provide a reference for controlling the spread of PWD in China, in this study, we accurately assessed the risk of the continued spread of PWD in Northeast China; a correlative species distribution model (MaxEnt) (RM = 1, AUC = 0.9904) was used to evaluate China’s climate suitability for PWD. The effects of climate factors on the spread of PWD in Northeast China were studied using Liaoning Province as an example by analyzing the relationship between the changes in average precipitation, average temperature, average relative humidity, average vapor pressure deficit, average wind speed, average sunshine duration and the area of the PWD epidemic over the past five years. These results suggest that with the change in climate, the areas suitable for PWD have expanded, and certain previously unsuitable areas for its distribution have become suitable. Temperature and precipitation were found to play key roles in the occurrence and damage of PWD, and hot and arid conditions favored the spread of PWD. It is recommended that for areas within the suitable range of PWD but not yet epidemic areas, quarantine should be strengthened to prevent the further spread of PWD. In addition, special attention should be paid to epidemic areas with high temperatures and arid while the monitoring of PWD should be strengthened to achieve the early detection and timely treatment of infected epidemic trees. Our results indicate that PWD undoubtedly poses a major threat to Northeast Chinese pine species if climate change proceeds as projected. In the future, more attention should be paid to monitoring the northward spread of PWD, and further studies should consider meteorological data forecasts, which could facilitate timely control measures.

Water use dynamics of trees in a Pinus tabuliformis plantation in semiarid sandy regions, Northeast China

Quantifying tree water use and its environmental controlling mechanisms are significantly important for understanding of adaptation strategy of trees and plantation management in semiarid and arid regions. Here, tree water consumption and tree conductance of Chinese pine (Pinus tabuliformis) plantation were quantified using sap flow measurements. Environmental variables were measured concurrently during the growing seasons of 2019 and 2020. Results showed that daily, daytime and nighttime tree water consumption averaged 27.4, 24.7, and 2.7 kg d-1 across two years, respectively. Nighttime tree water consumption accounted for 10% of the daily’s, which was mainly used for recharging stem water storage deficit caused by daytime transpiration to avoid hydraulic failure. Daytime tree water consumption was more driven by solar radiation than by vapor pressure deficit. Moreover, daytime tree conductance was 0.9 mm s-1, and significantly decreased with increasing vapor pressure deficit and decreasing soil moisture, indicating that trees had strict stomatal regulation on tree transpiration. Scaling-up from tree to stand transpiration, daytime stand transpiration averaged 1.1 mm d-1 across two years, while accumulated stand transpiration was 112.8 mm and 126.8 mm in 2019 and 2020, respectively, accounting for 33% and 37% of precipitation. However, soil evaporation occupied 35% and 51% of precipitation in 2019 and 2020, respectively. This indicated that most of water in the plantation was consumed by soil evaporation. Difference between precipitation and sum of daytime stand transpiration, canopy interception, soil evaporation, and change in soil water storage was positive in two years, indicating that water budget was balanced. These findings indicated that Chinese pine trees had strict stomatal regulation on tree transpiration, and could recharge stem water storage deficit by nighttime sap flow. Moreover, stand transpiration occupied a small part of the water balance, and thus water supply was surplus, resulting in maintaining the stability of Chinese pine plantation.

Does resin tapping affect the tree-ring growth and climate sensitivity of the Chinese pine (Pinus tabuliformis) in the Loess Plateau, China?

Resin tapping could affect water and nutrient transport processes in Chinese pine trees, rendering them more vulnerable to extreme climatic events, such as drought, and affecting the ecological function of forests in semi-arid regions. This study evaluated how resin tapping affects the tree-ring growth and climate sensitivity of Chinese pine in the Loess Plateau. We compared tree-ring growth patterns between the tapped and untapped faces of tapped trees, and investigated tree-ring growth and its response to climate between tapped and untapped trees in a forest stand during the 1967–2017 period. Tapped trees showed asymmetrical growth patterns after resin tapping, with narrower rings near the tapped face and wider ones near the untapped face. Furthermore, tapped trees had inter-annual variations consistent with those of untapped trees except for the years 2000 and 2001, with significantly lower values following resin tapping, and tree-ring growth then returning to normal. The climate response analysis indicated that the tree-ring growth of both tapped and untapped trees was negatively affected by monthly mean temperatures during the early growing season (May to July) in the post-resin-tapping period. Furthermore, tree-ring growth in tapped trees also revealed significant correlation with water vapour deficit and the Palmer drought index, which indicates that tapped trees are more vulnerable to drought. Further studies based on stable isotopes (i.e. δ13C, δ18O, and δ15N) could improve our understanding of the physiological mechanisms that regulate the effects of resin tapping on tree-ring growth.

Season-specific changes in telomere length and telomerase activity in Chinese pine (Pinus tabulaeformis Carr.)

Telomeres have lately received considerable attention in the development of deciduous tree species. In order to determine season-specific changes in telomere length and telomerase activity in evergreen tree species, Chinese pine trees (Pinus tabulaeformis Carr.) were used as experimental materials. In this study, we examined the correlation among telomere length, telomerase activity, and temperature in P. tabulaeformis during the course of an annual developmental cycle. A statistical analysis showed that the lengths of telomeres were significantly different between new and old leaves in each month. During the annual developmental cycle, the telomere lengths in Chinese pine tree leaves increased from May to June 2012, remained stable or increased slightly from June to August 2012, decreased sharply from August 2012 to January 2013, and then increased from January to April 2013. Telomerase activities could be detected in both new and old leaves from May 2012 to April 2013 and the telomerase activities in new leaves are higher than in the old each month. Additionally, there were similar trends between the changes in telomere length and mean monthly temperature from May 2012 to April 2013, and opposite trends were shown between the changes in telomerase activity and mean monthly temperature. Therefore, telomere length and telomerase activity varied with the season. Telomere length was positively correlated with temperature and telomerase activity was negatively correlated with temperature during the annual developmental cycle.

May-June maximum temperature reconstruction from mean earlywood density in north central China and its linkages to the summer monsoon activities.

Cores of Pinus tabulaformis from Tianshui were subjected to densitometric analysis to obtain mean earlywood density data. Climate response analysis indicates that May–June maximum temperature is the main factor limiting the mean earlywood density (EWD) of Chinese pine trees in the Shimen Mountains. Based on the EWD chronology, we have reconstructed May–June maximum temperature 1666 to 2008 for Tianshui, north central China. The reconstruction explains 40.1% of the actual temperature variance during the common period 1953–2008. The temperature reconstruction is representative of temperature conditions over a large area to the southeast and northwest of the sampling site. Preliminary analysis of links between large-scale climatic variation and the temperature reconstruction shows that there is a relationship between extremes in spring temperature and anomalous atmospheric circulation in the region. It is thus revealed that the mean earlywood density chronology of Pinus tabulaformis has enough potential to reconstruct the temperature variability further into the past.

A tree-ring-based June-September mean relative humidity reconstruction since 1837 from the Yiwulü Mountain region, China

The study of humidity is important for better understanding the past climatic variations. However, there have been few long-term humidity reconstructions using tree-ring widths worldwide. Here, we present a June–September mean relative humidity (MRH69) reconstruction from AD 1837 to 2011 using Chinese pine trees (Pinus tabulaeformis Carr.) from the Yiwulü Mountain region in northeastern China. The reconstruction explained 39.8% of the instrumental variance during the calibration period. We found that precipitation only influenced the MRH69 on an annual scale (high frequency), but the mean maximum temperature (MMT) impacted the MRH69 both on an annual scale (high frequency) and decadal time scale (low frequency). The MRH69 reconstruction showed a consistently increasing trend from AD 1881 to 1990, after which it diminished sharply. More high humidity years occurred after the 1960s and more low humidity years occurred before the 1960s. In the study area, MRH69 decreased along with global warming after the 1980s. On the decadal scale, there were five high-value MRH69 intervals: 1842–1850, 1865–1871, 1898–1902, 1823–1927 and 1932–1997; there were five low-value intervals: 1851–1864, 1872–1897, 1903–1922, 1928–1931 and 1998–2006. In addition, the MRH69 reconstruction showed the large-scale representativeness of sea–land coupling. On the decadal scale, our MRH69 reconstruction varied synchronously with the Arctic Oscillation index (AOI), suggesting that the AOI might be linked with MRH69 in the Yiwulü Mountain region. Historical documents and meteorological data indicate that flooding (or drought) often occurred in the years with higher (or lower) humidity compared with the moving average values of the mean relative humidity (MRH).

Tree-ring stable carbon isotope-based May–July temperature reconstruction over Nanwutai, China, for the past century and its record of 20th century warming

Growth anomaly of trees in some regions was detected under current episode of rapid warming. This raises a dilemma for temperature reconstructions by using tree-ring width which is believed to be the most important proxy on inter-annual temperature reconstruction during the past millenniums. Here we employed the tree-ring δ13C to reconstruct temperature variations for exploring their potential on capturing signals of rapid warming, and to test how its difference with the tree-ring width based reconstruction. In this study the mean May–July temperature (TM–J) was reconstructed over the past century by tree-ring δ13C of Chinese pine trees growing in the Nanwutai region. The explained variance of the reconstruction was 43.3% (42.1% after adjusting the degrees of freedom). Compared to a ring-width temperature reconstruction (May–July) from the same site, the tree-ring δ13C-based temperature reconstruction offered two distinct advantages: 1) it captured a wider range of temperature variability, i.e., at least May–July, even over a longer part of the year, January–September; and 2) the reconstruction preserved more low-frequency climate information than that of ring width did.The 20th century warming was well represented in the Nanwutai tree-ring δ13C temperature reconstruction, which implied that stable carbon isotope of tree rings potentially represents temperature variations during historical episodes of rapid warming. A spatial correlation analysis showed that our temperature reconstruction represented climate variations over the entire Loess Plateau in north-central China. Significant positive correlations (p < 0.1) were found between the temperature reconstruction and ENSO, as well as SSTs in the Pacific and Indian Oceans. The reconstruction showed the periodicities of 22.78-, 4.16-, 3.45–3.97- and 2.04–2.83-year quasi-cycles at a 95% confidence level. Our results suggested that temperature variability in the Nanwutai region may be linked to Pacific and Indian Ocean SST variations and solar activity.

Characterization of the effects of inter-tree competition on source–sink balance in Chinese pine trees with the GreenLab model

We investigate the characteristics of individual tree response to competition on source–sink balance through the functional–structural plant model GreenLab. Four Chinese pine (Pinus tabulaeformis Carr.) trees were destructively sampled and were divided into two groups: high-density group and low-density group. First, the effects of density on organ dimensions and on organ relative mass were analysed based on experimental measurements. These were primary indicators of the plant response to competition. Second, the hidden parameters of the GreenLab model, as well as a tree-specific characteristic surface, were estimated using the data of total tree biomass for needle and wood compartments, for each of the four trees in parallel. The quality of the fitting is finally validated using data of individual organ mass at shoot level for the sampled branches. The Mann–Whitney Student’s t test showed that there were significant differences between the shoot attributes of the two groups for shoot diameter, shoot biomass and needle biomass. No significant difference was found for current year shoot lengths of the two groups. The parametric identification of the model allowed estimating and comparing the amount of biomass that was allocated to primary growth and to secondary growth in the two density conditions. It showed that biomass allocated to secondary growth (ring compartment) was the most strongly affected by density, and that the organ demand satisfaction ratio profiles of each of these trees were a relevant, integrated indicator of the tree state.

Effect of extracts of Chinese pine on its own seed germination and seedling growth

The allelopathic potential of Chinese pine (Pinus tabulaeformis Carr.) against its own seed germination and seedling growth was tested with aqueous extracts (0.01, 0.02, 0.05, and 0.10 g·mL−1) obtained from different organs (roots and litter needles) at different individual ages (12, 52, and 110 years old). The results showed that root and litter extracts had different effects on seed germination and seedling growth, and the effects varied with the concentrations, the organs, and the tree age of extracts. The strongest stimulatory effect on seed germination of Chinese pine was exposed to 0.02 g·mL−1 root extract from the 110 years old Chinese pine trees and exposed to 0.02 g·mL−1 litter extract from the 12 years old Chinese pine trees. Meanwhile, the strongest stimulatory effect on growth of Chinese pine seedlings was exposed not only to 0.01 g·mL−1 root extracts from the 110 years old Chinese pine but also to 0.01 g·mL−1 litter extract from the 12 years old Chinese pine. The promoting effect of the extracts of root on seed germination and seedling growth increased in the order of 12, 52, and 110 years old. The promoting effect of the extracts of litter on seed germination and seedling growth increased in the order of 110, 52, and 12 years old. Our results suggested that litter leachates or root exudates of Chinese pine may influence the natural regeneration within Chinese pine stands via the release of allelochemicals into the environment.

Impact de l’activité solaire, anomalie globale de température de l’air et oscillation décadaire pacifique sur les cernes d’arbres en milieu urbain

A tree ring width chronology developed from 58 samples taken from Chinese pine trees (Pinus tabulaeformis Carr.) growing in Shenyang city was studied to analyze the effects of solar activity, Global Surface Air Temperature Anomalies (GSATA) and the Pacific Decadal Oscillation (PDO) on annual radial growth. An excellent response of tree rings to solar activity and global environmental change was revealed, indicating that these urban Chinese pine trees are a suitable proxy for Sun-Earth system research despite their location in Shenyang, an industrial city. The information derived from annual growth rings of urban Chinese pine trees coincides with records from undisturbed trees in a natural location, and demonstrates significant synchronous response to solar activity in the periodic bands of 5–8, 10–12 and 20–30 years. The wave signal of tree growth was also affected and amplified by the combined effect of the PDO from 1900 to 2004 and GSATA from 1880 to 2004 with a short lag time, revealing 5–8, 11–13, and 20–23 year oscillatory modes. At 20–30 year timescale, Chinese pines validated the strong GSATA influence signal at 20.8 years, and may be the primary cause of the 20 and 23 year periodic waves of tree rings. Shenyang urban tree ring growth also showed high frequency variation (2—4 y) that may be due to low periodicity of solar activity, GSATA, PDO and local climate variations, especially in the 2–4 years band width.

Solar activity, global surface air temperature anomaly and Pacific Decadal Oscillation signals observed in urban outskirts tree ring records from Shenyang, China

A tree ring width chronology constructed from multiple samples taken from Chinese pine trees growing in outskirts of Shenyang city in Liaoning Province (China) was studied for the first time in relation to solar activity, global surface air temperature anomalies and the Pacific Decadal Oscillation. The work revealed an excellent response of urban tree growth to solar activity and global climate change, show as the time variation of the main periodicities in the Sun–Earth indices and its corresponding variation as recorded in tree rings, indicating that these urban Chinese pine are a suitable proxy for Sun–Earth system research in heavy industrial region, like Fuling Mausoleum that is located in Shenyang. Chinese pines show significant synchronous response to solar activity, in the periodic band 5–8 years, 10–16 years and 20–30 years. At the same time, the wave signal of tree growth was also affected, or even amplified by the combined effect of the PDO and GSATA with a short lag time, revealing 6, 13.2, 16.6 and 23.2 years oscillatory modes. At 20–30 years timescales, Chinese pines validated the strongest PDO and GSATA influence signal at 26 years and 20.8 years, respectively, and the 20.8 years fluctuation of GSATA may be the first cause of the tree ring 23.5 years periodic waves. Urban tree ring growth is also more sensitive to low periodicity, especially in the 2–5 years band width.

Influence of earlywood–latewood size and isotope differences on long-term tree-ring δ 13C trends

Inter-annual δ 13C values of α-cellulose in two Chinese pine trees ( Pinus tabulaeformis Carr.) exhibit a long-term decline of more than 2‰ for the period of 1896 to 1990 AD. This decline is much larger than the decrease in atmospheric δ 13C caused by industrialization since 1850 AD. Here we present evidence that long-term trends of 13C/ 12C in tree rings also reflect ecophysiological effects superimposed on the anthropogenic trend. These effects are associated with the decreasing/increasing productivity of earlywood or latewood associated with the changing growth history of the tree. Theoretical calculations show that long-term decreases in the 13C/ 12C ratios in tree rings may be enhanced or reduced by these ecophysiological effects, depending on the pattern of seasonal differences in tree-ring δ 13C values. Based on seasonal δ 13C analyses, the influence of these effects on δ 13C values for one of these trees (HL02) has been removed. The corrected data are in agreement with the observed size and timing of the δ 13C decline in atmospheric CO 2. This study suggests that long-term tree-ring δ 13C data used to infer the anthropogenic impact on atmospheric CO 2 carbon isotope compositions may be improved by correcting for possible ecophysiological effects using measurement of latewood and earlywood ring widths and seasonally resolved isotopic analysis. Removal of growth effects may also benefit the assessment of long-term changes in the water use efficiency in response to increasing atmospheric CO 2 concentrations.