Gönpa Gang—The First Application of Dendrochronological Dating to Study the Traditional Architecture of Upper Mustang (Nepal)

Gönpa Gang is an example of the traditional Buddhist architecture of Upper Mustang. It is also the first monument in Upper Mustang to be studied using the dendrochronological dating method. The gönpa is a two-story building of imposing size, made from simple elements of Tibetan architecture, namely masonry walls, timber posts, and beams. A total of 14 samples were collected from elements on both the ground and the first floor. The limited number of samples results from the cultural and religious character of the object under study. Only the elements consistent with the structure and the space arrangement, interpreted as original features, were examined. Microscopic observation and the analysis of the anatomical features of all 14 samples resulted in the identification of Himalayan pine (blue pine), Pinus wallichiana A.B. Jacks. Intra-annual density fluctuation, false rings, and missing rings were detected. From 14 samples collected in Gönpa Gang, 18 series were worked out. Thus, 15 series from 12 samples were synchronized and used for the development of the mean chronology, UMGG_m, with a total length of 160 rings. The chronology covers the period from 1524 to 1683. Examination of the Gang Gönpa wood resulted in the age determination of 13 elements. The results were compared with architectural stratification by Harrison and historical data from written sources. The timber used in the gönpa comes from the Southern Mustang area. The examined wood demonstrates a correlation with the timber used in the Upper Mustang historical buildings further north.

Climate Response in Tree-Rings of Sawara Cypress [Chamaecyparis pisifera (Siebold & Zucc.) Endl.] in Poland

Sawara cypress [Chamaecyparis pisifera (Siebold & Zucc.) Endl.] is originally from Japan. It was introduced to Europe in the latter half of the 19th century (in England and Holland in 1861, and in Poland in 1864). The aim of this study was to examine the influence of climatic conditions on tree-ring width among Sawara cypress populations growing in Poland. Additionally, other indicators determining the growth-climate relationship for the studied tree species were investigated such as false rings, missing rings, or frost rings. Five stands of Sawara cypress from northwestern and central Poland were selected for study. Samples were taken from 97 trees, using Pressler borers at breast-height. Tree-ring widths were measured down to 0.01 mm. Climatic data came from weather stations located the nearest to the study plots. Tree-ring width in the studied populations of Sawara cypress varies (from 1.94 to 4.47 mm). The oldest Sawara cypresses grow in Glinna Arboretum and are nearly 130 years old. The youngest ones grow in Rogów Arboretum (67 years old) and Wirty Arboretum (58 years old). Ten regional pointer years, including six negative and four positive ones, were determined for local chronologies. Negative pointer years were associated with the occurrence of cold winters and water shortages in summer. Positive pointer years are mostly periods with a warm winter season, early and warm spring, and with high precipitation totals during summer months. Correlation and response function analysis corroborates the results yielded by pointer year analysis. False rings carry an additional information on pluvial conditions in the summer period, and frost rings are an aid in dating dendrochronological series and indicate the occurrence of both very cold winters and persistent ground frost occurrences in the spring period. In comparison to native conifers, the Sawara cypress can be regarded as a fast-growing species. The knowledge of acclimatization, growth rate, and growth-climate relationship may be useful, especially in the time of a rapidly changing climate, increasing human impact, and highly intensified invasion of insect and fungal species attacking native forest-forming taxa.

Explorative analysis on red mullet (Mullus barbatus) ageing data variability in the Mediterranean

The uncertainty in age estimation by otolith reading may be at the root of the large variability in red mullet (Mullus barbatus) growth models in the Mediterranean. In the MEDITS survey, red mullet age data are produced following the same sampling protocol and otolith reading methodology. However, ageing is assigned using different interpretation schemes, including variations in theoretical birthdate and number of false rings considered, in addition to differences in the experience level of readers. The present work analysed the influence of these variations and the geographical location of sampling on red mullet ageing using a multivariate approach (principal component analysis). Reader experience was the most important parameter correlated with the variability. The number of rings considered false showed a significant effect on the variability in the first age groups but had less influence on the older ones. The effect of the theoretical birthdate was low in all age groups. Geographical location had a significant influence, with longitude showing greater effects than latitude. In light of these results, workshops, exchanges and the adoption of a common ageing protocol based on age validation studies are considered fundamental tools for improving precision in red mullet ageing.

Wood anatomy and growth ring boundaries of Copaifera lucens (Fabaceae)

ABSTRACTThe wood anatomy of Copaifera lucens Dwyer was studied with an emphasis on its growth ring boundaries. Growth rings are visible to the naked eye and demarcated by marginal parenchyma bands and, sometimes, by thick-walled fibers in the latewood. Secretory canals are associated with marginal parenchyma bands, but not all marginal parenchyma bands are associated with canals. Paratracheal parenchyma is vasicentric to lozenge-aliform. Rays are 1–4-seriate, heterocellular and non-storied. Vessels are visible to the naked eye, diffuse, predominantly solitary, some in multiples, sometimes filled with gums. Crystals present. Wood anatomical characteristics of C. lucens are in agreement with those previously reported for other species of Copaifera. In addition to what had already been described for C. lucens, we observed gelatinous fibers, and some bifurcate fibers, and extremely rare clustered vessels. The growth ring boundaries are well-defined in mature wood but less distinctive near the pith. There are also partial and confluent (wedging) rings, which are difficult to classify by anatomy only, but which represent false rings and complicate tree-ring analysis in this species.

Respuesta del crecimiento de Pinus oocarpa Schiede a variables climáticas en el noroeste de Lagunas de Montebello, Chiapas, México

Dendrochronological studies are used to reconstruct some climatic variables; in México these studies have focused on central and northern temperate forests where trees present well defined annual rings. Few studies have been carried out in the southern part of the country where annual ring growth is not easily identified and thus makes cross-dating problematic. We analyzed the dendrochronological potential of Pinus oocarpa Schiede for reconstructing climatic variables in the northwest portion of Lagunas de Montebello, Chiapas. We used a selective sampling approach and collected 65 increment cores from 34 trees. While our samples showed a high frequency of false rings (8 to 60 %), we were able to date 30 samples from 22 trees (46 %) using standard dendrochronological techniques and developed total chronologies for total ring width, earlywood, and latewood for a period of 91 years (1925-2015). We found a significant influence of mean precipitation and mean maximum and minimum temperature over the annual ring growth of P. oocarpa in the period 1961-2004. Our results show that winter-spring precipitation (January-May) was the most important for the species’ annual ring growth. However, we found the highest correlation between spring (March-May) precipitation and the earlywood chronology (r = 0.719, P < 0.05). The earlywood chronology also showed potential for reconstructing minimum temperatures (March to May) (r = 0.732, P < 0.05), while the latewood chronology had the potential for reconstructing the maximum temperature (September to January) (r = 0.714, P < 0.05). These results showed that P. oocarpa can be used to reconstruct climatic variables in the Mexican tropics. We recommend that new areas with older trees should be explored in order to increase the depth of chronologies and reconstruct climate records several centuries into the past.

RADIAL GROWTH DYNAMICS OF Khaya ivorensis TREES FROM EXPERIMENTAL PLANTATION

ABSTRACT The objective of this study was to characterize the formation of growth rings in Khaya ivorensis wood, as well as to analyze the variation in the morphology of the vessel elements, aiming to understand the growth of this species in experimental plantations. Disks from the bases of five trees were collected, and after polishing the cross-section, demarcation of the growth rings limits was carried out. The anatomical study of the wood was conducted with the purpose of characterizing the rings, and their width was measured by means of scanned images of the disks. A historical series of data was obtained concerning the diameter of the trees to establish a correlation with the width of the rings measured over the years. The growth rings limits of African mahogany wood are demarcated by a thin layer of marginal parenchyma, and the presence of false rings has been observed. Significant annual growth correlation of 0.62 was observed among the trees, being the radial increment of irregular wood in the first years (wide and narrow rings), and highlighting the 3rd and 11th year of growth in which the largest increases were observed due to a biological adaptation tendency to the environment and the occurrence of thinning carried out in the planting area, respectively.

False rings in the white pine (Pinus strobus) of the Outaouais Hills, Québec (Canada), as indicators of water stress

False rings are intra-annual bands of wood darker than the adjacent wood. They have been reported for several species of Pinus, although not previously for white pine (Pinus strobus L.). In southwestern Quebec, false rings were found to be very common among white pine, an indication that the species is sensitive to water stress in this region. False rings were analyzed on 110 trees from 12 mature stands. A false ring database was built, and false ring chronologies were established and analyzed for two groups of sites (rocky outcrops and shallow soils). The years 1955, 1959, and 1988 were those with the highest occurrence of false rings (62% to 90% of all stems). Factors predisposing false ring formation include the cambial age of stems bearing false rings and drainage conditions (dry rocky outcrop sites). Triggering factors were climatic events occurring during the four-month growing season. Years with low precipitation correlate with years featuring a higher occurrence of false rings. High summer temperatures may also be involved, as they explain the distribution of false rings in all frequency classes. In areas where they form, false rings in white pine can be used as diagnostic rings and as indicators of water stress.

Seasonal shift in the climate responses of Pinus sibirica, Pinus sylvestris, and Larix sibirica trees from semi-arid, north-central Mongolia

In light of a significant increase in the warming trend observed in recent decades in semi-arid Mongolia, tree-ring attributes and anomalies were analysed to detect potential changes in the growth–climate relationship. In a moisture-limited environment, an increase in temperature could cause a shift in the seasonal response of trees to climate. Chronologies were developed for the dominant tree species (Larix sibirica Ledeb., Pinus sibirica Du Tour, and Pinus sylvestris L.) from north-central Mongolia. In addition to annual ring width, both earlywood and latewood width were measured, and tree-ring anomalies such as false rings and light rings were systematically identified. Earlywood width was mainly associated with precipitation in the year prior to ring formation and early growing season conditions. Temperature was associated with current year growth and mainly influenced latewood development. False rings were good indicators of early summer droughts, whereas light rings were mainly associated with a cold end of summer. A seasonal shift in the significance of monthly climate variables was observed in recent decades. This displacement presumably resulted from changes in the timing and duration of the growing season. Tree growth starts earlier in spring and is now affected by late summer to early autumn climate conditions.