Decline In Radial Growth Research Articles

Tree ring isotopic composition, radial increment and height growth reveal provenance-specific reactions of Douglas-fir towards environmental parameters

In the search of timber species being tolerant towards summer droughts, which are expected to be more frequent in future, Douglas-fir is often discussed as a potential alternative for spruce in Central Europe. To assess physiological and growth reactions of Douglas-fir provenances towards climate- and weather-related environmental conditions we took advantage of a provenance trial with three sites in south-western Germany located along an elevation gradient. We examined six different provenances of Douglas-fir from North America for oxygen (δ18O) and carbon (δ13C) stable isotope composition in tree rings as well as for radial increment for a 7 year period and long-term height growth. Our results show that different Douglas-fir provenances clearly vary in their drought sensitivity at the driest and warmest site in the valley as shown by the radial growth decline in the extreme dry and hot year 2003. The growth decline in the provenances Pamelia Creek, Cameron Lake, Duncan Paldi and Conrad Creek could be clearly attributed to a reduction in stomatal conductance as assessed by the relations between δ18O and δ13C in the tree rings. These responses were not related to the long-term average climate at the places of origin of the provenances and the provenances with the lowest long-term (height) growth potential were the ones least affected in radial increment by the extreme drought of 2003. When selecting suitable Douglas-fir provenances, which are adapted to the climatic conditions projected for the future we thus might need to take into account the trade-off between the adaptation to extreme drought periods and the long-term growth performance. Site-specific evaluations of the probability of extreme drought events are thus needed to select the appropriate provenances.

Effects of climate change on biomass carbon sequestration in old-growth forest ecosystems on Changbai Mountain in Northeast China

Old-growth forest ecosystems are large carbon pools, and recent research has found that old-growth forests generally serve as global carbon sinks. However, the impact of climate change on the capacity for carbon sequestration in old-growth forest ecosystems is uncertain. Combining data from 30-year monitoring of permanent plots with that measuring variations in radial growth of dominant trees in an old-growth forest on Changbai Mountain in Northeast China, this study investigated the net biomass carbon sequestration and the effects of climate warming on carbon sequestration for dominant living trees in this forest ecosystem. The results showed that in 2010 biomass carbon density for living trees was 201.22tha−1 in Korean pine and broad-leaved mixed forest (KBF), 106.46tha−1 in spruce-fir forest (SFF), and 89.49tha−1 in Erman’s birch forest (EBF). During the past 30years the net biomass carbon density has increased in KBF and EBF, with annual net increases of 1.79tha−1 and 1.22tha−1, respectively; while net carbon density has decreased in SFF, with an annual net decrease of 0.55tha−1. Despite the increase of carbon density in KBF, climate warming has contributed to a decrease of 0.96tha−1 in biomass carbon sequestration for the period of 1981–2010, an amount equivalent to 1.8% of total stand biomass carbon increase. The increase in net carbon density in KBF was primarily age- or size-related, since that forest is still maturing. The decreased density in SFF may be caused by climate-induced radial growth decline and mortality of dominant trees in these stands. For the period of 1981–2010, climate-induced decrease of carbon sequestration in SFF was 7.30ha−1. Wind-related tree mortality in SFF may have led to the stand carbon sequestration decrease of 75.09tha−1, about 10.3 times that induced by climate warming. In EBF, climate warming has led to a small increase in stand carbon sequestration, and the increase in net carbon density was also primarily age- or size-related, reflecting the fact that this forest is also still maturing. Our study also suggests that the dominance of Korean pine in KBF will decrease and that of Manchurian ash will increase under continuing climate warming, which is in agreement with the results from previous forest models.

Temporal patterns of radial growth in declining Austrocedrus chilensis forests in Northern Patagonia: The use of tree-rings as an indicator of forest decline

Using dendrochronology, combined with tree- and stand-level information, we reconstructed the temporal dynamics of ‘ mal del ciprés’, a widespread decline of Austrocedrus chilensis forests in Argentina. We developed 12 new site-specific ring-width chronologies representing the growth of trees with no external (crown) or internal (radial growth) symptoms of decline. By comparing the ring-width series of individual trees with these reference chronologies, we detected reduced radial growth, likely due to ‘ mal del ciprés’, in 301 symptomatic and dead overstory trees out of 1082 sampled trees . Radial growth decline also occurred in 67 living trees with asymptomatic crowns providing evidence that radial growth decline can be an early indicator of ‘ mal del ciprés’. The length of the radial growth decline averaged 27 years for all trees and was 29 and 22 years for living symptomatic and dead overstory trees, respectively; the maximum decline length was 80 years. At the site level, the onset of radial growth decline ranged from the early 1920s to the 1960s, preceding dates reported in historical records. By 1979, ⩾75% of trees per site exhibited radial growth decline. We conclude that decline in radial growth precedes crown symptoms in at least some A. chilensis trees in forests with ‘ mal del ciprés’. Reduced radial growth prior to external crown symptoms implies that water uptake had been reduced, possibly because of root damage from Phyophthora or drought or their interactions. It also suggests salvage harvests that aim to eradicate trees with crown symptoms and facilitate growth of residual trees may not be the most effective management response to ‘ mal del ciprés’.

Short-term effects of prescribed burning on radial growth of Douglas-fir trees in south central British Columbia

Radial increment of Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco) trees in uncut and partially cut and grazed and ungrazed dry cool Interior Douglas-fir forests near Isobel Lake in southern central British Columbia was measured for 2-year periods before and after prescribed burning in burned and unburned (control) areas. Parameters thought to influence the effects of prescribed burning on tree growth – characteristics of the tree and its immediate environment, adjacent surface and ladder fuels, and fire effects – were also measured. Burning caused a decrease in tree radial growth. The proportional change in radial tree growth was not related to degree of cutting or the presence of cattle grazing, but was negatively correlated with preburn radial growth, tree size, and also with some fire effect variables, particularly char height, suggesting that an increasing proportional decline in radial growth was associated with increasing tree size and with increasing fire severity. Soil nutrient (N, S, P, K, Mg or Ca) level was not a significant determinant of tree growth. The best prediction model could only explain 23% of the variation in the change in radial growth. Our results show that the effects of fire on Douglas-fir radial growth are complex and difficult to predict with the variables measured.

Dendrochronological Analysis of Subfossil Fraxinus from the Middle and Late Holocene Period in Lithuania

Dendrochronological investigations on subfossil European ash (Fraxinus excelsior L.) wood found in two bogs of Western Lithuania are presented. Radiocarbon dating has revealed that Fraxinus grew in the Middle and Late Holocene, from approximately 4700 BC to 1500 BC. It is proposed that the growth of Fraxinus at these bogs was limited by differing hydrological regimes. Rising soil water levels induced a long decline in radial growth followed by a sharp reduction (up to 51%) in ring widths before the trees died. Until now, forest history in Lithuania was mostly based on results from palynological studies. This research demonstrates the potential of using dendrochronology to extend the distribution record of Fraxinus in the Baltic region during different periods of the Holocene.

Using dendrochronology to model hemlock woolly adelgid effects on eastern hemlock growth and vulnerability

This study examined the relationship between eastern hemlock (Tsuga canadensis (L.) Carr.) crown condition and changes in radial growth associated with infestation by hemlock woolly adel- gid Adelges tsugae (Homoptera: Adelgidae) (HWA). Tree-ring chronologies of eastern hemlock were used to develop a binomial decline index based on three consecutive years of below average growth. Radial growth decline was modeled, using logistic regres- sion, as a function of an extensive array of tree, crown, and site variables that were collected over an 11 year period in Delaware Water Gap National Recreation Area. Some site-related variables such as site-location and aspect were significantly related to decline probabilities when considered individually. However, the total proportion of response variance accounted for was low, and the only site variable included in the final model was mean plot-level HWA infestation level. For every 1% increase in mean percent HWA infestation per plot, there was an 8% increase in the likelihood that a tree would be classified as being in decline. Tree crown variables such as live crown ratio, crown density, and the modified ZBadj index, a combination of foliage transparency and branch dieback, had the most explanatory power, both individually and in the final model. These crown variables were relatively accu- rate predictors of the degree of hemlock growth decline during HWA infestation.

Response of tree growth to a changing climate in boreal central Canada: A comparison of empirical, process-based, and hybrid modelling approaches

The impact of 2 × CO 2 driven climate change on radial growth of boreal tree species Pinus banksiana Lamb., Populus tremuloides Michx. and Picea mariana (Mill.) BSP growing in the Duck Mountain Provincial Forest of Manitoba (DMPF), Canada, is simulated using empirical and process-based model approaches. First, empirical relationships between growth and climate are developed. Stepwise multiple-regression models are conducted between tree-ring growth increments (TRGI) and monthly drought, precipitation and temperature series. Predictive skills are tested using a calibration–verification scheme. The established relationships are then transferred to climates driven by 1× and 2 × CO 2 scenarios using outputs from the Canadian second-generation coupled global climate model. Second, empirical results are contrasted with process-based projections of net primary productivity allocated to stem development (NPP s). At the finest scale, a leaf-level model of photosynthesis is used to simulate canopy properties per species and their interaction with the variability in radiation, temperature and vapour pressure deficit. Then, a top-down plot-level model of forest productivity is used to simulate landscape-level productivity by capturing the between-stand variability in forest cover. Results show that the predicted TRGI from the empirical models account for up to 56.3% of the variance in the observed TRGI over the period 1912–1999. Under a 2 × CO 2 scenario, the predicted impact of climate change is a radial growth decline for all three species under study . However, projections obtained from the process-based model suggest that an increasing growing season length in a changing climate could counteract and potentially overwhelm the negative influence of increased drought stress. The divergence between TRGI and NPP s simulations likely resulted, among others, from assumptions about soil water holding capacity and from calibration of variables affecting gross primary productivity. An attempt was therefore made to bridge the gap between the two modelling approaches by using physiological variables as TRGI predictors. Results obtained in this manner are similar to those obtained using climate variables, and suggest that the positive effect of increasing growing season length would be counteracted by increasing summer temperatures. Notwithstanding uncertainties in these simulations (CO 2 fertilization effect, feedback from disturbance regimes, phenology of species, and uncertainties in future CO 2 emissions), a decrease in forest productivity with climate change should be considered as a plausible scenario in sustainable forest management planning of the DMPF.

Exploring Interactions between Pollutant Emissions and Climatic Variability in Growth of Red Spruce in the Great Smoky Mountains National Park

Concern exists as to the status of red spruce (Picea rubens Sarg.) in the Great Smoky Mountains, with evidence both for and against an unprecedented decline in radial growth during the past century. On the basis of a dendrological record from 1850 to 1998, our analyses support a decline in radial growth starting as early as the 1940s through to the 1970s; in the 1970s there was a reversal of this decline. In comparing trees near ridges (2000 m) with those in draws (1500 m), we found differences in the (a) timing of the decline, (b) rate of decline, and (c) homogeneity of the decline, with trees near ridges showing earlier, faster, and more homogeneous declines than trees in draws. We hypothesized that changes in climatic conditions and/or atmospheric pollutants, both of which changed beyond ranges of natural variability, were related to the observed decline in radial growth. In trees near ridges, up to 67.1% of changes in radial growth could be explained by a combination of climatic conditions (7.6%) and annual emissions of nitric oxides (NOx) and sulfur dioxide (SO2) (an additional 59.5%). In trees from draws, up to 38.3% of the changes in radial growth could be explained by climatic conditions only. A conceptual model is presented, where trees in naturally acidic soils with low base saturation provide a sensitive signal for the changing nature of acidic pollutants, but trees in anthropogenically acidifying soils with an initially higher baser saturation provide a signal that is confounded by a transient increase of calcium (Ca) and magnesium (Mg) in the soil that results in a transient increase in radial growth.

Radial Growth of Oak and Aspen Near a Coal-Fired Station, Manitoba, Canada

Eighteen stands of bur oak (Quercus macrocarpaMichx.) and trembling aspen (Populus tremuloides Michx.) were sampled and analyzed using dendrochronological methods to study the potential effects on tree growth of emissions from a 132 MW coal-fired generating station. Sixteen stands were sampled within a 16-km radius of the station, and two control stands were sampled outside of the range of influence, at distances . 40 km. All stands showed similar radial growth patterns from 1960‐2001, regardless of distance from or direction relative to the generating station, and a number of stands, including the controls, had below average growth after 1970. Both species were significantly affected by climatic factors, showing decreased radial growth with increasing June temperature. The species differed in their growth responses to spring precipitation and temperature in the previous October. One bur oak site displayed marked radial growth decline beginning in the mid-1970s, strongly pronounced following 1977. This decline does not appear to be related to emissions from the station, but is suspected to be a result of poor site conditions (shallow soil developed over calcareous till), confounded by a change in drainage (a road was built adjacent to the stand in 1977, perpendicular to the direction of drainage). The below average growth seen in 1970‐ 2001 across most stands is likely attributable to stand dynamics and age effects.

Reduction of stem growth and site dependency of leaf injury in Massachusetts black cherries exhibiting ozone symptoms

Leaf ozone symptoms in natural ecosystems are increasingly reported but ozone effects on tree growth and the mediation of site conditions are still little documented. This study tests two hypotheses: (1) leaf injury in black cherry is associated with decline in radial growth, (2) symptoms are more prevalent on mesic sites. On sites supporting black cherry across Massachusetts, tree growth and leaf ozone injury were surveyed in 1996 using a randomized plot network established in the 1960s. Forty-seven percent of 120 trees sampled for ozone symptoms were symptomatic with generally low levels of injury. Over a 31-year period symptomatic trees had 28% lower stem growth rates than asymptomatic trees. Ozone symptom expression was enhanced in well growing stands on moister, cooler and more elevated sites. Ozone appeared to increase environmental stress and had a more pronounced effect on growth in better growing black cherry stands. This complicates management decisions as thinning increases growth and moisture availability.

The impact of a needleminer (Epinotia subsequana) outbreak on radial growth of silver fir (Abies alba) in the Aragón Pyrenees: A dendrochronological assessment

Summary We report the first dendrochronological assessment on the effects of the Epinotia subsequana (Lepidoptera: Tortricidae) needleminer on Abies alba forests in the Aragon Pyrenees (northeastern Spain), near the southwestern distribution limit of A. alba. We built local residual ring-width chronologies, in fifteen A. alba stands, using dendrochronological techniques. We found a strong decrease in radial growth in the 20th century, during the 1996–98 period, only at the sites AS (Paco Asieso, 42°39' N, 00°17' W) and DI (Diazas, 42°38' N, 00°06' W). There were previous surveys of E. subsequana outbreaks and fir defoliation, in the studied sites area, in 1995–96. They showed that the radial-growth suppression was caused by E. subsequana. We compared radial growth in the non-defoliated stands with mean regional chronology. The greatest decline in radial growth was in 1996–97. Thus, there was a 1–2 year lag in radial growth suppression following the defoliation. The recovery of radial growth occurred in 1998–99.

Use of tree rings to investigate the onset of contamination of a shallow aquifer by chlorinated hydrocarbons

Oaks ( Quercus velutina Lam.) growing over a shallow aquifer contaminated by chlorinated hydrocarbons were studied to determine if it was possible to estimate the approximate year that contamination began. The annual rings of some trees downgradient from the contaminant release site contained elevated concentrations of chloride possibly derived from dechlorination of contaminants. Additionally, a radial-growth decline began in these trees at approximately the same time that chloride became elevated. Growth did not decline in trees that contained smaller concentrations of chloride. The source of elevated chloride and the corresponding reductions in tree growth could not be explained by factors other than contamination. On the basis of tree-ring evidence alone, the release occurred in the late 1960s or early 1970s. Contaminant release at a second location apparently occurred in the mid- to late 1970s, suggesting that the area was used for disposal for at least 5 years and possibly longer.

A dendrochronological study of black and scarlet oak decline in the Missouri Ozarks

Examination of tree-ring data revealed important relationships regarding red oak decline in the Missouri Ozarks. Red oaks, mainly black and scarlet oak, exhibiting greater than 30% crown dieback had significantly lower present-day growth rates compared with trees with less than 30% dieback. Red oaks with declining crowns first showed significantly lower radial growth than trees that are healthy at present in the 10 years following years of severe drought in southeastern Missouri. These dates for initiation of radial growth decline varied by tree age, and were 1936 for 60–79-year-old trees and 1952 for 40–59-year-old trees.

Relation between genetic diversity and pollution impact in a 1912 experiment with East European Pinussylvestris provenances

Results are presented of genetic variation and growth decline due to pollution for 11 European populations, 1 Turkish population, and 1 Siberian population of Scots pine (Pinussylvestris L.) growing in a provenance experiment established in 1912 in Pulawy, southeastern Poland. Since 1966 this area has been subjected to acute pollution from a nitrogen-fertilizer factory emitting high levels of SO2, NOx, NH3, and other toxic compounds. A significant negative correlation was found between genotype polymorphism indices and radial growth decline since 1966 assessed using tree-ring analysis (r = −0.58, P = 0.04). Populations with the highest values for genotype polymorphism index, numbers of alleles per locus, and numbers of genotypes per locus exhibited less of a decline in radial growth than those populations with lower values for these parameters. The results provide experimental support for the hypothesis that genetically richer populations are better adapted to changing conditions and suggest that such populations are less sensitive to air pollution in terms of growth reduction.

Management Implications of Ash Yellows in Northeastern Hardwood Stands

Abstract This paper identifies management implications for forest stands affected or potentially affected by ash yellows (AshY) based on results from studies on the response of forest structure and composition to AshY and the interrelationship of AshY, drought, and radial growth decline of white ash. Specifically, the synthesis of these studies compares the structure and composition of forests classified as either declining or nondeclining based on patterns of white ash radial growth and identifies the role of AshY in these forests. Data were collected from 41 plots in 6 northeastern states. The incidence of AshY at the stand level was associated with high white ash density and importance value, increased white ash mortality in the upper canopy, stand ages generally less than 60 years, and a high degree of forest fragmentation. The presence of AshY in individual white ash was generally associated with a decline in radial growth. The radial growth of white ash unaffected by AshY could recover from drought stress, but white ash affected by AshY apparently could not. Managers of forest stands having a high white ash density, particularly in droughty stands or in areas with a high degree of forest fragmentation, should encourage greater overstory species diversity. North. J. Appl. For. 8(3):115-118.

Ash Yellows, Drought, and Decline in Radial Growth of White Ash

The effect of MLO infection and drought on the radial growth of white ash trees was measured using standard dendrochronological techniques. Both MLO infection and drought stress caused reductions in the radial growth of white ash, but not all MLO-infected trees declined in radial growth. The effect of regional drought on the radial growth of white ash was investigated on 15 of 41 permanent research plots by comparing summary tree ring indices of the white ash within these plots with mean Palmer Drought Severity Indices for April through September (.)

Red spruce decline on Whiteface Mountain, New York. II. Relationships between apical and radial growth decline

Understanding the relationship between apical and radial growth decline can contribute toward the evaluation of hypotheses regarding causal mechanisms of red spruce decline. The etiology of red spruce decline in montane spruce-fir forests of the northeastern United States includes loss of foliage at branch apices, crown dieback, and unreversed radial growth decline since the 1960s. Demographic analyses of crown damage and radial growth decline for red spruce on Whiteface Mountain, New York, indicate that large, canopy-emergent trees with exposed crowns exhibit greater decline than codominant trees within an intact canopy. In this paper, radial growth decline is shown to have been coincident with decreased apical growth and increased incidence of injury to terminal leaders. Incidence of leader mortality is greatest for canopy-emergent red spruce or trees with exposed crowns, similar to patterns described for radial growth. This relationship suggests that the post-1960 decline of red spruce on Whiteface Mountain is caused, at least in part, by stresses that act directly on the crown.

Tree-ring model interprets growth decline in natural stands of loblolly pine in the southeastern United States

Annual ring widths and ring areas from 131 even-aged, natural, well-stocked stands of loblolly pine (Pinustaeda L.) in the Piedmont region were analyzed to reveal possible causes of a previously reported decline in radial growth. A linear aggregate model was used to separate independent factors that are known to contribute to radial growth variation in this species. Stand, site, and climatic conditions were reconstructed for each stand for the 36-year period 1949–1984 from previous inventories and from weather records at appropriately located stations. Within each of six 5-year age-classes, the model identified declines in both ring width and ring area associated with stand density, climate changes, and the passage of time. Regional climate first ameliorated this decline as pine stands passed from droughty conditions early in the 36-year period to a favorable climate during the middle of the period, and the decline accelerated later with the return of dry conditions toward the end of the period. The tree-ring model simulates a decline in radial increment in trees in natural pine stands between the ages of 20 and 45 years in the Piedmont which has averaged 1% per year since 1950. Part of the downward trend was attributed to increased competition, part to regional drought, and a considerable part to unidentified factors, possibly regional atmospheric deposition.

Aluminum-Induced Calcium Deficiency Syndrome in Declining Red Spruce

Prolonged suppression of cambial growth has apparently caused a decline in radial growth in many mature red spruce, Picea rubens. Surveys indicate that this decline occurs in trees throughout the natural range of red spruce and is independent of elevation, tree size, and age class. In addition, crowns of mature red spruce at high elevations across the northeastern United States have been dying back. Understanding the physiological basis for the growth decline is essential for the judicious management of the red spruce resource. A sequence of events is inferred through which an imbalance of aluminum and calcium in the fine root environment reduces the rate of wood formation, decreases the amount of functional sapwood and live crown, and leaves large trees more vulnerable to extant secondary diseases and insect pests.

An analysis of climate and competition as contributors to decline of red spruce in high elevation Appalachian forests of the Eastern United states.

Long-term growth patterns of red spruce (Picea rubens Sarg.) were analyzed from increment cores collected from over 1000 trees at 48 sites in the eastern United States. Principal objectives were the evaluation of the distribution, timing, and uniqueness of observed patterns of decreasing radial growth during the past 25 years and the examination of stand competition and climate as factors contributing to observed changes.Our analyses focused on historical records of spruce mortality and approximately 200 years of radial growth data to search for historical precedents for current trends. In this work we have used time series analysis to detect the temporal frequency of significant negative or positive shifts in radial growth rates, an analysis of relationships between a stand competition index and observed changes in growth and mortality, and modeling of past growth-climate relationships to determine whether recent growth changes could be predicted based on climate.Collectively, these analyses indicate that the observed growth decreases of surviving red spruce trees at northeastern sites with high mortality have been anomalous during the past 20 to 25 years with respect to both historical annual growth patterns and past relationships to climate or stand development at these sites. In general, reductions in radial increment that have also been noted at southern high elevation sites but not at low elevations occurred 5 to 10 years later than at northern sites and represent less substantive departures from growth trends predicted by linear climate models.These results suggest that regional and not local stresses have triggered the observed decline in radial growth of red spruce at these sites. While climatic change may have contributed to observed changes, the degree of radial growth suppression observed is greater than would be expected based on past growth-climate relationships. This unique relationship of growth to climate suggests the influences of either recent, unique combinations of climatic stresses or the possibly interactive intervention of other regional-scale stresses, such as atmospheric pollution.