Dendrochronologia最新文献

Climate change is predicted to cause asymmetric warming and increased precipitation variability across different seasons. These changes and their effects may be captured in subannual seasonwood measures of tree growth (i.e., earlywood, latewood). Longleaf pine is a foundational tree species throughout the broad southeastern U.S. Its latewood growth may be more variable and sensitive to climate change than earlywood, but prior studies have geographical and ecological sampling limitations. Here, we use dendroecological methods to develop ring-width and seasonwood (earlywood, latewood, and adjusted latewood) chronologies and analyze climate-growth relationships for longleaf pine from eight sites in the Southern Coastal Plain of Florida, USA. Sites spanned a range of environmental conditions to generate an ecologically representative dataset. We evaluated chronology strength and variability and determined monthly and seasonal correlations with precipitation and temperature. We furthermore evaluated climate-growth stationarity using a moving response function and bootstrapped transfer function stability tests. We found adjusted latewood chronologies were most climatically sensitive although totalwood chronologies had higher interseries correlations. Totalwood measurements were more variable than early- or latewood year to year. Tree growth was positively correlated with summer precipitation at six out of eight sites and negatively correlated with late summer maximum temperatures at six out of eight sites. Negative relationships between growth and maximum temperature occurred earlier in the year at southern sites and the positive effect of June precipitation on tree growth was notable, found at six out of eight sites. However, the strength and significance of climate-growth relationships were non-stationary through space and time, with shifts largely occurring post-1950s. Longleaf pine at its southern range extent was less sensitive to climate than more northern populations, which may indicate non-linear responses to warming captured at the species’ range margin. Our results highlight dynamic climate-growth relationships related to the broad range of environmental conditions where longleaf pine is found.

Climate variations are influencing the growth dynamics of forests, with direct consequences on their biomass productivity. The scientific community, concerned with refining the understanding of tree-climate interactions, has recently used tree-ring density to elucidate ecological mechanisms that may be overlooked by earlywood, latewood, and total tree-ring widths. In this study, we model the sensitivity of intra-annual wood density in tree-rings for 15 species distributed across a broad bioclimatic and biodiverse gradient in the Mexican Republic. Maximum, minimum, latewood, and earlywood density (MaxD, MinD, LWD, and EWD, respectively) were associated with climatic data through correlation analysis and mixed-effects models. Maximum temperature (T_MAX) and precipitation (P) stand out as key drivers of temporal density fluctuations, notably influencing MaxD and LWD as indicators of hydroclimatic regime changes. MinD and EWD are less responsive but prove valuable in gauging environmental sensitivity. Abies religiosa from the Southern Semi-Arid Highlands and Picea martinezii from Mediterranean California were the most responsive species to climate variables. These results open new paradigms for densitometry as a proxy for ecological processes that species face in anticipating dieback phenomena, mortality rates, and resilience mechanisms, with implications for productivity and carbon rates in the face of predicted climate variations. However, the wood density-climate relationship is even more complex, and integrative research combining other proxies (e.g., wood anatomy and chemical composition) is recommended to refine wood density variations and understand the causes of the interspecific differences found in this study.

Dendroclimatic research faces the challenge of selecting appropriate detrending methods for retaining low-frequency signals in temperature reconstructions. Among the numerous methods available to dendrochronologists, regional curve standardisation (RCS) and the signal-free approach in combination with RCS (SF-RCS) are increasingly used to preserve the full spectrum of temperature variance in tree-ring data. Here, we apply RCS and SF-RCS to tree-ring width (TRW) and maximum latewood density (MXD) datasets composed of only living and combined living and relict trees from northern Scandinavia. Whereas RCS and SF-RCS produce highly similar chronologies when applied to composite (living-plus-relict) datasets, particularly for MXD, both methods fail to establish chronologies coherent with regional temperature trends when applied to living-tree datasets. Additional tests including pruning of well-replicated living-tree datasets, to approximate the heterogenous age-structure of composite datasets, reveal improved results and coherent trends in MXD. While this demonstrates the applicability of joint detrending and pruning techniques to retain meaningful low-frequency variance in living-tree MXD chronologies, similar improvements were not achieved with TRW, likely because of the much stronger age-trend inherent to this widely used proxy. Further tests with other tree species and in alpine environments are needed to verify these findings. However, such assessments require an adjustment of tree-ring sampling protocols to increase replication to 50+ trees per site including old and young individuals to facilitate data pruning.

Forest management plays a crucial role in preserving and enhancing the delivery of ecosystem services, whereas dendrochronological methods can play a significant role in this regard. In the Azores archipelago, with a temperate oceanic climate, with low thermal amplitude, and mild and relatively wet Summers, Cryptomeria japonica (Thunb. ex L.f.) D.Don is the main timber production species. It has been extensively planted for timber production and erosion control, being the mainstay of the regional forestry chain, with a rotation period of 30 years. Although dendrochronological studies have targeted this species elsewhere, this dendrochronological study in the Azores aimed to better understand its climate-growth relationships in the archipelago. For this purpose, we sampled 140 trees, in a total of 361 wood cores samples. Following standard dendrochronological methods, we obtained four site chronologies from different volcanic complexes in São Miguel island. We used a stepwise modelling approach, with Random Forest, Principal Component Analysis and Generalized Linear Models. Our results suggest that despite year-round precipitation in the Azores, C. japonica is adversely affected by warm Winter and Summers, while on site SC it benefits from these conditions. As previously observed, precipitation may be overshadowed by temperature-driven mechanisms in C. japonica. Our spatial analysis resulted into climate-growth associations with similar directions for all site chronologies. In the future, higher Winters and Summer temperatures could lead to increased water stress and reduced growth rates. This should be considered when projecting the future distribution and productivity of C. japonica forests under different climate change scenarios. To ensure the long-term survival of this economically important tree species, adaptation responses should include genetic and conservation measures. Our findings provide baseline information for defining management approaches for this strategic species.

Snow avalanches are among the most important disturbances in mountain ecosystems. The effects of avalanches on the endemic Pinus heldreichii and Pinus peuce forests in the Pirin Mountains in Bulgaria are poorly understood. These forests are among the few remaining old-growth forests with preserved natural dynamics in Europe. However, the ongoing development of tourist infrastructure at the borders of some of the best-preserved Pinus heldreichii and Pinus peuce forests close to Bansko ski resort leads to increased tourist pressure. Many backcountry skiers and snowboarders venture beyond the resort boundaries, practicing their activities in these forests and avalanche tracks and couloirs within them. The objective of our study was to collect tree-ring cores from Pinus peuce and Pinus heldreichii trees affected by avalanches and verify the specific types of damages and tree responses characteristic for the species and region. Then using the collected data, we aimed at reconstructing the years in which specific areas were affected by avalanches and in this way obtain data on the magnitude of larger events. Our study shows that large magnitude avalanches (LMA) in the vicinity of Bansko ski resort in the Pirin Mountains in Bulgaria occurred dozens of times in the 20th century. On average the period between LMAs ranged between 9 and 20 years with the shortest period between two such events in one couloir being 2 years. Avalanches affected forests high on the couloir banks and left traces in the tree rings related to the mechanical impact that snow avalanches had on the surviving trees. In the studied tree-ring cores of Pinus peuce and Pinus heldreichii the most informative types of responses were sharp growth suppressions, including missing rings, followed by reaction wood and in less cases visible scars and callus tissue. Our data for frequent large avalanches shows that is necessary to address the avalanche risk with high priority especially for the Palashica couloir, which directly threatens the lower parts of the ski runs as well as other facilities in Bansko ski resort.

Kyrgyzstan features the largest naturally occurring walnut forests in the world. Their high plant biodiversity, including wild relatives to modern-day fruit species such as apple and pear, make them a valuable guardian of genetic diversity. Further, walnut forests have a high economic importance for the country. Climate change, however, poses a major threat to these ecosystems, in particular since rises in temperature are projected that are well above global average. As studies on effects of changing environmental conditions on the growth of walnut are missing, we investigate the climate sensitivity and temporal stability thereof as well as extreme growth responses of walnut along its full elevational gradient in Kyrgyzstan. Whereas we expected to find a shift from water- to temperature-limitation over the elevational gradient, which may move upwards with recent warming, we found walnut growth to be temperature-limited along the entire elevational gradient. In recent decades, negative correlations between the drought index SPEI and tree growth, however, weakened. An up until now low importance of drought stress for walnut growth is also substantiated by a pointer-year analysis. Overall, our results show that walnut growth is already affected by climate change, though imminent risks of drought-induced vitality loss seem still low. With ongoing climate change, this may, however, rapidly change.

Dendrochronology is a discipline that uses tree rings to study the history and dynamics of the earth system, such as climate change, natural disasters, and human activities. This study aims to evaluate the development of dendrochronology and its track in China from 1990 to 2022 using a bibliometric analysis approach. We screened the Web of Science Core Collection for documents related to dendrochronology and analyzed them according to indicators related to production, cooperation, citation, and keywords. Our study revealed that the number of dendrochronological publications increased continuously, reaching more than 800 in 2021, with the USA and China being the top two countries. The cooperation network of dendrochronology was mainly centered between North America and Europe, with China having a moderate level of collaboration with other countries and regions like the USA and Canada. Comprehensive research has been conducted within diverse fields of dendrochronology in the world and in China, but dendrochronological research focusing on forestry and climatology represented a slightly higher proportion of research originating from China. The integration of dendrochronology with other disciplines and techniques, such as remote sensing, artificial intelligence, and modeling, may be hotspots in future research, as indicated by the increasing co-occurrence analysis of keywords in the most recent years. This study suggests that Chinese Dendrochronology still requires improved international collaboration, diversified research topics beyond climate reconstructions, and more emphasis on tree-ring methods to advance this discipline globally, despite of increasing rank of publications in the past decade.

The secondary growth phenology of trees, also known as wood phenology, plays a vital role in assessing the timing of carbon sequestration in forests. However, its spatio-temporal variability and determinants in the Northern Hemisphere remain debated. Here, we presented a meta-analysis using secondary growth phenology data based on dendrometer monitoring of 59 tree species and 84 sites to explore the drivers and temporal connections of phenology across seasonal arid and humid regions in the Northern Hemisphere. We found spring temperatures and precipitation co-regulated the start of secondary growth (SOG) in spring arid regions, and SOG advanced with the increase in spring temperatures and precipitation. However, SOG was only influenced by spring temperatures in spring humid regions. The end of secondary growth (EOG) indicated strong correlations with autumn temperatures only in autumn arid regions but not in humid regions. Interestingly, the earlier SOG promoted advancement of the time of maximum secondary growth rate (MOG) and EOG both in seasonal humid and arid regions, while the end of secondary growth in the previous year (prEOG) negatively affected SOG only in seasonal arid regions. The legacy effects of previous phenological events on subsequent ones should be integrated into phenological prediction models to help accurately assess global carbon, water, and energy cycles.

The published literature of the past 20 years expresses inconsistent terminology for the Blue Intensity (BI) method that could lead to confusion in analysis and interpretation. In this technical note we propose a standard terminology based around the prevalent use of BI for the variant that is positively correlated with wood density derived from X-ray and equivalent wood anatomical techniques. We highlight significant practical advantages of this standard terminology for data analysis, scientific interpretations as well as archiving, and provide some cautionary examples that could occur if not adhering to this terminology. In future studies using BI, we recommend to explicitly clarify that the standard terminology is used with the following phrase: The BI data produced in this study is consistent with the ‘2024 BI standard terminology’.

Dendrogeomorphology allows for annual dating of various hazardous geomorphic processes in afforested areas. However, there is a lack of detailed knowledge about spatial extent of dated growth disturbances in the whole stems, which is a crucial factor for the selection of an appropriate sampling strategy. In this study, growth disturbances were analysed in the stems of five juvenile Norway spruces (Picea abies (L.) Karst.) and five juvenile Common larches (Larix decidua Mill.) growing on a slope affected by mass-movements. The analysed growth disturbances were: i) reaction wood and ii) tree-ring eccentricity. The relationships between stem curvature and properties of the growth disturbances were studied to offer potential recommendations for sampling. It was found that reaction wood was consistently present at all stem heights in the given event tree ring. Angle extent of the reaction wood tended to decrease with successive tree rings, although an increase in angle extent was observed at higher stem heights (in the case of P. abies). Main direction of the reaction wood tended to be deviated mostly in a near-tilt direction. The properties of the reaction wood had weak associations with both tree-ring eccentricity and stem curvature. Overall, both tree species exhibited similar values of tree-ring eccentricity. Greater eccentricity values appeared mostly in the tilt sampling direction and one of two lateral sampling directions. There was not apparent pattern in the tree-ring eccentricity values observed at different stem heights. Overall, eccentricity had weak influence on stem curvature. To sum it all, both juvenile P. abies and L. decidua trees are good recorders of the two growth disturbances tested. However, differences in the sensitivity of trees to recording events in their annual ring series should be taken into account to achieve the greatest dating potential.