Short-term resin tapping activities had a minor influence on physiological responses recorded in the tree-ring isotopes of Chinese pine (Pinus tabuliformis)

Resin tapping might affect tree-ring growth, but details on the physiological responses of trees to resin tapping are still lacking, particularly for long-term responses. This study aimed to explore the physiological processes underlying resin-tapping of Chinese pine (Pinus tabuliformis) by using tree-ring stable isotopes. We compared tree-ring earlywood and latewood stable carbon (δ¹³C) and oxygen (δ¹⁸O) isotopes in the pre-resin tapping and post-resin tapping period for tapped trees and compared their values between tapped and untapped trees and their responses to climate variables in a forest stand from 1984 to 2017. Furthermore, we used a dual isotope model to distinguish between the effects of the photosynthetic assimilation rate and stomatal conductance. Results indicated that tapped and untapped trees showed similar inter-annual variation for two isotopes, while the absolute values of tapped trees were slightly (P > 0.05) lower than tapped trees in the two years following resin tapping. Climate response analysis indicated that resin tapping had no significant effect on climatic sensitivity for either stable isotope. Earlywood stable isotopes were mainly influenced by temperature, relative humidity, and Palmer Drought Severity Index (PDSI) from May to July, while latewood isotopes were mainly influence by relative humidity form July to August and PDSI from July to September. The conceptual model results indicated that resin tapping lead to a slight, but not significant, decrease in the intrinsic water-use efficiency caused by increased stomatal conductance for the first two to three years following resin tapping. We conclude that tree-ring physiological responses could be less affected by short-term resin tapping activities.     

Linkages between forest growth,climate, and agricultural production are revealed through analysis of seasonally-partitioned longleaf pine (Pinus palustris Mill.) tree rings

We established a five-century long tree-ring chronology partitioned between earlywood and latewood growth to examine intra-annual climate response and attempt to establish linkages to agricultural production. Longleaf pine earlywood and latewood width chronologies spanned the period 1491–2017 (527 years) and constitute one of the longest records achieved for this species. High monthly correlations were found between latewood growth and summer-fall Palmer Drought Z-Index. Correlations were consistently significantly positive for June through October. Intra-annual growth of earlywood and latewood were positively correlated for the full period of record, but exhibited variability in correlation strength through time. Conversely, earlywood and prior-year latewood were also frequently correlated, but correlations were found to switch between positive and negative association, possibly in response to Atlantic Ocean temperatures. Annual yields of major crops are coupled with latewood growth, representing a new and potentially valuable proxy for linking agricultural yields to climate proxies over multiple centuries.     

Bacteria associated with ectomycorrhizas of slash pine (Pinus elliottii) in south-eastern Queensland, Australia

Bacterial communities associated with ectomycorrhizal and uncolonized roots of Pinus elliottii (slash pine) collected from a plantation in south-east Queensland, Australia, were investigated, using cultivation-dependent and -independent methods. Denaturing gradient gel electrophoresis (DGGE) analysis of 16S rRNA gene PCR products obtained using a cultivation-independent approach revealed that bacterial communities associated with ectomycorrhizal root tips differed significantly from those associated with roots uncolonized by ectomycorrhizal fungi. DGGE analysis of cultivable bacterial communities revealed no significant difference between ectomycorrhizal and uncolonized roots. Neither analytical approach revealed significant differences between the bacterial communities associated with ectomycorrhizal roots colonized by a Suillus sp. or an Atheliaceae taxon. Cloned bacterial 16S rRNA genes revealed sequence types closely related with that of Burkholderia phenazinium, common in both ectomycorrhizal-colonized and -uncolonized roots, while sequence types most similar to the potentially phyopathogenic bacteria Burkholderia andropogonis and Pantoea ananatis were only detected in ectomycorrhizal roots. These results highlight the possibility of global movement of microorganisms, including putative pathogens, as a result of the introduction of exotic pine plantations.     

The variable climate response of Rocky Mountain bristlecone pine (Pinus aristata Engelm.)

Recent increases in temperature over the semi-arid western United States have been shown to exacerbate drought, reducing streamflow, and increasing stress on ecosystems. Our understanding of the role temperature played during drought in the more distant past is far from complete. While numerous tree-ring proxy records of moisture provide evidence for past extreme droughts in this region, few contemporaneous tree-ring proxy records of temperatures exist. This limits our ability to evaluate the variable influence of temperature on drought over past centuries and to contextualize the present interplay of moisture and temperature during more recent drought events. It is also important to understand the complexity of climatic interactions that produced drought under natural variability prior to evaluating the potential impacts of future climate change. In response to this knowledge gap, we undertook the first extensive evaluation of climate sensitivity in Rocky Mountain bristlecone pine (Pinus aristata Engelm.), focusing on the potential for developing new multi-century proxy records of both temperature and precipitation. We isolated dominant patterns of growth variability among trees from ten ring-width datasets across the Southern Rocky Mountains of Colorado and New Mexico and assessed their response to climate. We utilized both an empirical orthogonal function (EOF) analysis and a modified form of hierarchical cluster analysis to produce time series representing growth patterns in P. aristata. The results indicate a widespread June drought stress signal with a high potential for multi-millennial reconstruction. We also found a positive minimum temperature response during late summer, evident only at lower frequency and co-occurring at locations with the June drought stress signal. The potential for temperature reconstruction will require further investigation into the physiological linkages between P. aristata and climate variability. The presence of multiple climate responses within P. aristata sampling sites highlights the need for particular care when including P. aristata in regional climate reconstructions.     

土壤水分对湿地松幼苗光合特征的影响

通过设置常规供水(CK)、轻度干旱(T1)、水饱和(T2)、水淹(T3)4个处理组,研究湿地松当年实生幼苗在不同土壤水分条件下的光合生理响应及叶绿素荧光特性。结果表明:不同水分处理对湿地松幼苗的叶片气体交换参数、水分利用效率(WUE)、光合色素、叶绿素荧光参数等指标有不同的影响;其中,T3的光合色素含量最低;T2、T3组的湿地松幼苗表现出较低的净光合速率(Pn)、电子传递速率(ETR)和PSⅡ光化学的量子效应(ΦPSⅡ),但与其他耐水淹植物相比,T3条件下的湿地松幼苗仍具有较高的Pn,说明湿地松幼苗具有较强的耐水淹能力;在T1条件下,湿地松幼苗具有较高的WUE和较低的蒸腾速率(Tr)、气孔导度(Gs)以对抗干旱的逆境,其Pn、PSⅡ最大光化学效率(Fv/Fm)、ETR和ΦPSII均有所下降,但仍能维持在相对正常的水平。研究证明,湿地松幼苗具有一定的耐淹耐旱特性,可运用于三峡库区消落带的植被重建。     

Plant regeneration through multiple adventitious shoot differentiation from callus cultures of slash pine (Pinus elliottii)

A plant regeneration system through multiple adventitious shoot differentiation from callus cultures has been established in slash pine (Pinus elliottii). Influences of seven different basal media on callus induction, adventitious shoot formation, and rooting were investigated. Among the different basal media, B5, SH, and TE proved to be suitable for callus induction and plantlet regeneration. Multiple adventitious shoot formation was obtained from callus cultures of slash pine on B5, SH, and TE media containing indole-3-butyric acid, N6-benzyladenine, and thidiazuron. Scanning electron microscopy demonstrated the early development of adventitious shoots derived from callus cultures. These results indicate that an efficient plant regeneration protocol for micropropagation of slash pine had been established. This protocol could be most useful for future studies on genetic transformation of slash pine.     

A partial genetic linkage map of slash pine (Pinus elliottii Engelm. var. elliottii) based on random amplified polymorphic DNAs

A set of 420 random, 10-base, oligonucleotide primers was screened for random amplified polymorphic DNA (RAPD) fragments within a sample of eight megagametophyte DNAs of a single slash pine (Pinus elliottii Engelm. var. elliottii) tree. The apparently repeatable RAPD fragments were further characterized within a sample of 68 megagametophytes from the same tree. Fragments segregating in a 11, present-to-absent, ratio were classified and mapped using multi-point linkage analysis. The analysis revealed 13 linkage groups of at least three loci, ranging in size from 28 to 68 cM, and nine linked pairs of loci. The 22 groups and pairs included 73 RAPD markers and covered a genetic map distance of approximately 782 cM. Genome size estimates, based on linkage data, ranged from 2880 to 3360 cM. Using a 30-cM map scale and including the 24 unlinked markers and the ends of the 13 linkage groups and nine linked pairs, the set of RAPD markers accounts for approximately 2160 cM or 64–75% of the genome. This extent of genomic coverage should allow for the efficient mapping of genes responsible for a reaction to the causal agent of fusiform rust disease, Cronartium quercuum (Berk.) Miyabe ex Shirai f. sp. fusiforme.     

Spatiotemporal variability of stone pine (Pinus pinea L.) growth response to climate across the Iberian Peninsula

Climate warming and increasing aridity have impacted diverse ecosystems in the Mediterranean region since at least the 1970s. Pinus pinea L. has significant environmental and socio-economic importance for the Iberian Peninsula, so a detailed understanding of its response to climate change is necessary to predict its status under future climatic conditions. However, variability of climate and uncertainties in dendroclimatological approach complicate the understanding of forest growth dynamics. We use an ensemble approach to analyze growth-climate responses of P. pinea trees from five sites along a latitudinal gradient in Spain over time. The growth responses to April-June precipitation totals were stronger in the north than in the south. Since the 1950s, the sensitivity of growth to April-June precipitation increased in the north and decreased in the south. Meteorological drought usually started in May in the southern sites, but in June-July in the northern sites. The water deficit in the southern sites is thus greater and more limiting for tree growth, and this likely accounts for the lower growth sensitivity during these months. Our results indicate that P. pinea has a high degree of plasticity, suggesting the species will withstand changing climatic conditions. However, growth response to drought regimes varies among P. pinea populations, suggesting that different populations have different capacities for acclimation to warmer and drier climate, and this may influence future vegetation composition.     

Effect of ‘elicitors’ on extracellular peroxidase activity in suspension-cultured slash pine (Pinus elliottii Engelm.)

Peroxidase activity in the growth medium of suspension-cultured slash pine was observed over time and eliciting chitosan concentrations from non-damaging to lethal were followed. First significant differences in peroxidase activity were observed within 12h exposure to chitosan. Extracellular peroxidase activity decreased as chitosan increased until considerable cell death occurred and medium peroxidase activity increased. Chitin and fusiform rust mycelium elicited decreased peroxidase activity with no significant difference in viability. The highest levels of elicited lignification corresponded to the lowest extracellular peroxidase activity. Controls and the greatest chitosan concentration (which elicited 100% cell death) showed the highest peroxidase activity and no lignification.     

Bacterial stimulation of adventitious rooting on in vitro cultured slash pine (Pinus elliottii Engelm.) seedling explants

A bacterium has been isolated that initiates adventitious rooting when co-cultured under in vitro conditions with seedling-produced hypocotylary explants of slash pine (Pinus elliottii). Rooting efficiencies produced through bacterial-explant co-culture range from approximately 15% to greater than 90% over non-treated controls. Explant exposure to the root inducing bacterium has produced no obvious pathology in the regenerated plantlets. Seedling explants rooted by bacterial-explant co-culture have been successfully transitioned to ambient greenhouse conditions.     

Somatic embryogenesis in slash pine (Pinus elliottii Engelm): improving initiation of embryogenic tissues and maturation of somatic embryos

Plant Cell, Tissue and Organ Culture (PCTOC) - Slash pine (Pinus elliottii Engelm.) has strong adaptability, early growth and high turpentine yield, and it is widely planted in southern China....     

Effects of Hurricane Andrew on stands of slash pine (Pinus elliottii var. densa) in the everglades region of south Florida (USA)

Few hurricanes affect intact stands of subtropical pines. We examined effects of winds in the eyewalls of Hurricane Andrew, where wind speeds were >200 km h^–1, on all remaining large mainland stands of Pinus elliottii var. densa (south Florida slash pine) on limestone outcroppings (rocklands) in the everglades region of southern Florida. We measured densities and sizes of trees and assessed damage and mortality in plots in old-growth stands in the Lostman's Pines (LOP) region of Big Cypress National Preserve and in second-growth stands in the Pines West (PIW) and Long Pine Key (LPK) regions of Everglades National Park. We also examined age-size relationships using sections from trees killed by the hurricane in LOP and LPK. We used the data to predict effects of recurrent hurricanes on the structure and dynamics of the old-growth stand and to compare effects of hurricanes on old- and second-growth stands.Slash pine was resistant to hurricane winds. Most trees in stands (68–76%) were not severely damaged; mortality in the three regions averaged 17–25% shortly after the hurricane and 3–7% during the following year. Mortality was positively associated with tree size; mean tree sizes decreased and size-selective thinning occurred in all stands. Nonetheless, local mortality ranged from 3–4% to 50–60% among plots in all stands. Such local variation in mortality resulted from clustering of large trees, especially in old-growth stands, and from microbursts during the hurricane, which affected all stands. Recurrent, intense hurricanes are predicted to kill larger trees, slowly opening new patches and increasing sizes of extant patches, thus resulting in almost continual presence of openings suitable for recruitment in old-growth stands. Age-size relationships also indicated that large trees in old-growth stands may survive 2–3 centuries. The combination of frequent openings and wind resistance of large trees is predicted to result in old-growth stands that are highly uneven aged, with trees locally distributed in similar-aged patches. The extent to which such stands deviate from demographic equilibrium, as well as turnover rates within stands, are likely to increase as the frequency of recurrent, intense hurricanes increases.Damage and mortality differed in old- and second-growth stands. Large trees were more, but small trees less likely to be damaged in old- than second-growth stands. In contrast, mortality was significantly lower in old- (LOP: 16.9% ± 3.1 [mean ± s.e.]) than second-growth stands (PIW: 22.5% ± 2.0; LPK: 25.2% ± 2.7). Total hurricane-related mortality was 30–60% higher in second- than old-growth stands. Size class structure, more uneven in old- than second growth stands prior to the hurricane, diverged even more afterwards. Hurricane Andrew removed     

不同水分处理对湿地松幼苗生长与根部次生代谢物含量的影响

模拟三峡库区土壤水分变化特征,设置常规生长水分条件(NG组)、轻度干旱水分胁迫(MD组)、土壤潮湿(WS组)以及水淹(BS组)4个不同处理组,研究多种水分胁迫对湿地松(Pinus elliottii Engelm.)当年实生幼苗的生长与生理影响。结果表明:不同水分处理、时间对湿地松幼苗的生长、生物量、根系的草酸与酒石酸含量均产生显著的影响(P0.05,水分处理对茎生物量的影响例外)。与NG相比,MD、WS和BS均显著降低湿地松幼苗的高生长与叶生物量积累,但对茎生物量的影响均不显著。MD显著降低地径生长,与WS和BS显著增加地径生长正好相反。与此同时,MD、WS和BS能显著增加湿地松幼苗主根、侧根以及总根的草酸和酒石酸含量(MD主根的草酸含量例外)。在同一处理组内,湿地松幼苗根系草酸与酒石酸含量随着处理时间的延长呈现出不同的变化趋势。在多种水分逆境胁迫条件下,湿地松幼苗虽然在生长与生物量方面表现出一定的敏感性,但该树种幼苗较好的适应性特征仍然表现明显。因此,在对湿地松幼苗进行管护时,应当特别注意干旱环境下浇水、水淹环境下排水等土壤水分管理措施,确保湿地松幼苗的健康生长。     

Growth and response patterns of Picea crassifolia and Pinus tabuliformis to climate factors in the Qilian Mountains,northwest China

Different tree species exhibit different phenological and physiological characteristics, leading to complexity in inter-species comparison of stem radial growth response to climate change. This study explored the climate-growth responses of Qinghai spruce (Picea crassifolia) and Chinese pine (Pinus tabulaeformis) in the Qilian Mountains, Northwest China. Meanwhile, Vaganov-Shashkin model (VS-oscilloscope) was used to simulate the relationships between radial growth rates and phenology. The results showed that 1) in their radial growth patterns, Qinghai spruce showed a significant increasing trend, while Chinese pine showed a decreasing trend, and Qinghai spruce has a longer growing season than Chinese pine. 2) For the radial growth-climate dynamic response, Qinghai spruce was influenced in an unstable manner by the mean temperature in the mid-growing season of the current year and the late growing season of the previous year and by the mean minimum temperature in the mid-growing season of the current year, while Chinese pine was influenced in a stable manner by the mean temperature and mean maximum temperature during the growing season of the current year. 3) The radial growth rates of the two conifer species were limited by temperature at the initiation and cessation of growth and by soil moisture at the peak of growth. But Chinese pine was more severely affected by soil moisture than Qinghai spruce in the middle of growth. Therefore, different management and restoration measures should be taken based on the differences in ecological responses and physical and physiological properties of the two conifer species to climate change in the subalpine forest ecosystems in the semiarid and arid regions of Northwest China.     

An evaluation of english oak earlywood vessel area as a climate proxy in the UK

This research evaluates the usefulness of oak earlywood vessel area as a climate proxy in the western United Kingdom (UK). The results demonstrate that at this site earlywood vessel area contains a different environmental signal (March relative humidity) to a ring-width chronology developed from the same trees. The vessel area signal passes commonly used verification statistics and was found to be representative of the climate of a similar geographic area to other tree-ring proxies, albeit with a lower explained variance. Taking the average of all the vessels identified for each year weakened the reconstructed climate signal and it was found for this study that the average of the 10 largest vessels provided the strongest and most stable match. The results demonstrate earlywood vessel area of oak in the UK has potential as a climate proxy, but that further work to strengthen and characterise the climatic target variable controlling vessel area is required.     

Contrasting climate signals across a Scots pine (Pinus sylvestris L.) tree-ring network in the Middle Volga (European Russia)

Since the late-19th century, the Middle Volga has played a major role in the supplying grains and other agricultural products to European Russia. The study area is located in the south of sub-boreal forest in the north and in the forest-steppe in the south. Due to large seasonal differences in rainfall, agriculture in the region, especially in its southern part, strongly depends on hydroclimate variability. According to climate model forecasts, the frequency and intensity of droughts in the Middle Volga are expected to increase due to ongoing warming. Here we introduce 16 new Scots pine tree ring width (TRW) chronologies (Pinus sylvestris L.) from the region and use a dendroclimatological approach to determine what climatic factors drive radial growth. Our analysis revealed contrasting climate signals across the network of sites with chronologies from the north showing weak correlation with May temperature and precipitation (r = −0.27 and r = 0.28, respectively), while the southern sites demonstrated stronger relationships with climate in the first half of the vegetation season (May to July temperature, r = −0.26 to −0.43; May and July precipitation, r = 0.29–0.35). The northern sites did not demonstrate a strong growth response to the self-calibrated Palmer drought severity index (scPDSI) whereas the southern group was more drought sensitive had a strong drought response and positively correlates with scPDSI for the period from previous July to the current October (r = 0.27–0.56). Based on this strong relationship between southern TRW and scPDSI we reconstruct June-September scPDSI using the most sensitive sites (T04S, T06S, T08S) for the period from 1830 to 2014. The model explains 31% of variance. Our reconstruction shows droughts in 19th century: in 1831–33, 1851, 1853, 1859, 1863–65, 1880, 1891–92, 1897–98 and in 20–21th centuries: in 1906, 1921, 1936, 1939, 1967, 1975, 1996, 2010.     

秦岭北麓油松径向生长对气候变化的响应

以秦岭北麓南五台油松为样本,建立油松树轮宽度标准化年表(STD),研究油松径向生长与气候因子之间的相关性。结果表明: 秦岭北麓油松径向生长与前一年9月及当年5月水分因子呈显著正相关,与前一年11月温度因子呈显著正相关,与前一年10月、当年5月温度因子呈显著负相关。油松径向生长对不同气候因子响应均存在明显的滞后效应。油松径向生长与PDSI干旱指数具有较好的相关性,特别是与前一年9—12月、当年5月PDSI呈显著正相关。回归模型能较好地模拟树轮宽度指数与PDSI之间的关系,油松极宽窄轮的形成主要是干旱作用的结果。综合各种气候指标,PDSI能更好地反映研究区油松径向生长的特征。     

国外松衰退病原因的研究

对安徽省国外松大面积衰退和枯死原因的调查研究表明,造成这种衰退和枯死的现象是多方面因素共同作用的结果,是一种林木衰退病,该衰退病的发生原因：1）诱发因素：温度年较差较大、年降雨量分布不均镁、土壤粘重板结或容重过大、地势低汪积水、土壤瘠薄、林分密度过大;2）激化因素：干旱严重重复发生、割脂过早过度、霜冻、食叶害虫等害虫危害;松针褐斑病等病害侵害;3）促进因素：松枯梢病菌、根腐病菌、立木腐配病菌、天牛、小蠹虫等害虫危害。     

不同径级油松径向生长对气候的响应

建立了黑里河自然保护区油松年轮宽度年表,通过不同径级油松径向生长对逐月气候因子的响应关系,研究了干旱对不同径级油松径向生长的影响。结果表明:两个径级油松的年轮宽度指数达到极显著相关(R=0.943,P<0.01),其中小径级(平均胸径20 cm)油松年表的平均敏感度显著高于大径级(平均胸径43 cm)油松年表(P<0.01)。不同径级油松均与上年9月、当年2月及当年5—6月的降水显著正相关(P<0.05),与当年6月的平均温度显著负相关(P<0.05),此外,小径级油松还与当年7月的降水显著正相关(P<0.05);降水是影响油松生长的主要气候因子。不同径级油松的径向生长量在干旱年份均显著降低(P<0.01)且小径级油松的生长降低量显著高于大径级油松(P<0.01);不同径级油松生长量在干旱发生后1年左右的时间内均恢复正常且小径级油松恢复速度更快。     

Growth responses to climate and drought at the southernmost European limit of Mediterranean Pinus pinaster forests

Climate warming and increasing aridity may negatively impact forest productivity across southern Europe. A better understanding of growth responses to climate and drought in southernmost populations could provide insight on the vulnerability of those forests to aridification. Here we investigate growth responses to climate and drought in nine Pinus pinaster (maritime pine) stands situated in Andalusia, southern Europe. The effect of climatic variables (temperatures and precipitation) and drought on radial growth was studied using dendrochronology along biogeographic and ecological gradients. We analyzed old native stands with non-tapped and resin-tapped trees mixed, showing their usefulness in dendroclimatic studies. Our results indicate a high plasticity in the growth responses of maritime pine to climate and drought, suggesting that site aridity modulated these responses. The positive growth responses to spring precipitation and the negative responses to summer drought were stronger in the more xeric inland sites than in wet coastal ones, in particular from the 1980s onwards. The characterization of tree species’ responses to climate at the southern or dry limits in relation to site conditions allows improving conservation strategies in drought-prone forest ecosystems.