Tree Ages

Quantifying historical fire regimes provides important information for managing contemporary forests. Historical fire frequency and severity can be estimated using several methods; each method has strengths and weaknesses and presents challenges for interpretation and verification. Recent efforts to quantify the timing of historical high-severity fire events in forests of western North America have assumed that the "stand age" variable from the US Forest Service Forest Inventory and Analysis (FIA) program reflects the timing of historical high-severity (i.e. stand-replacing) fire in ponderosa pine and mixed-conifer forests. To test this assumption, we re-analyze the dataset used in a previous analysis, and compare information from fire history records with information from co-located FIA plots. We demonstrate that 1) the FIA stand age variable does not reflect the large range of individual tree ages in the FIA plots: older trees comprised more than 10% of pre-stand age bas...

Quantifying historical fire regimes provides important information for managing contemporary forests. Historical fire frequency and severity can be estimated using several methods; each method has strengths and weaknesses and presents challenges for interpretation and verification. Recent efforts to quantify the timing of historical high-severity fire events in forests of western North America have assumed that the "stand age" variable from the US Forest Service Forest Inventory and Analysis (FIA) program reflects the timing of historical high-severity (i.e. stand-replacing) fire in ponderosa pine and mixed-conifer forests. To test this assumption, we re-analyze the dataset used in a previous analysis, and compare information from fire history records with information from co-located FIA plots. We demonstrate that 1) the FIA stand age variable does not reflect the large range of individual tree ages in the FIA plots: older trees comprised more than 10% of pre-stand age bas...

Quantifying historical fire regimes provides important information for managing contemporary forests. Historical fire frequency and severity can be estimated using several methods; each method has strengths and weaknesses and presents challenges for interpretation and verification. Recent efforts to quantify the timing of historical high-severity fire events in forests of western North America have assumed that the "stand age" variable from the US Forest Service Forest Inventory and Analysis (FIA) program reflects the timing of historical high-severity (i.e. stand-replacing) fire in ponderosa pine and mixed-conifer forests. To test this assumption, we re-analyze the dataset used in a previous analysis, and compare information from fire history records with information from co-located FIA plots. We demonstrate that 1) the FIA stand age variable does not reflect the large range of individual tree ages in the FIA plots: older trees comprised more than 10% of pre-stand age bas...

W C used data from 322 natural longlcaf pine (Pinus pdustris Mill.) trees to include crown ratio as a continuous variable in taper equations. The data were divided into 10 crown-ratio classes and fitted taper equations into each class to detect trends in the coefficients. For application to longleaf pine, we replaced coefficients that exhibited a trend with crown ratio with a function of crown ratio. The inclusion of crown ratio as a continuous variable improved by at least 16 percent the mean square residual for both models. The authors' model performed better on the modeling dataset based on fit statistics and on the validation dataset. It also contained fewer parameters and was easier to rearrange to solve for height to a given diameter.

Persistence of stem defects, including bole sinuosity, large branch size and the occurrence of steep-angled branches (i,e., forks and ramicoms), and the efficiency of early selection against these traits, were investigated in 90 open-pollinated families of Douglas-fir (Pseudotsuga menziesii var. menziesii) from coastal Oregon. Trees originally measured for these traits at age 12 were remeasured at age 24 in three progeny test plantations. The majority of trees scored as having ramicom branches at age 12 (62%) still had them at age 24, but most forks (53%) had become ramicoms by the second measurement. Thus, there seems little need to score forks and ramicorns separately; simply counting the number of whorls with steep-angled branches seems sufficient for selection purposes. Branch size scores were relatively consistent between the two ages, but not scores for bole sinuosity. Because of low estimated individual and family heritability estimates (50.13 and 50.41, respectively), predicted genetic responses in DBH and individual stem-defect traits were only modest for this population. Nevertheless, with the exception of sinuosity, genetic correlations between comparable stem-defect traits at the two ages were strong (r , 2 0.82), and predicted responses in traits at age 24, from selection at age 12, were nearly as great as responses expected if selection was delayed until age 24. Branch size and occurrence of steep-angled branches wereunfavorably (positively) correlated with DBH (estimated r, = 0.56 and 0.41, respectively). Thus, it is important to include these stem defect traits as selection criteria in Douglas-fir breeding programs, if stem volume growth is to be improved without sacrificing wood quality.

Globally, mature forests appear to be increasing in biomass density (BD). There is disagreement whether these increases are the result of increases in atmospheric CO 2 concentrations or a legacy effect of previous land-use. Recently, it was suggested that a threshold of 450 years should be used to define mature forests and that many forests increasing in BD may be younger than this. However, the study making these suggestions failed to account for the interactions between forest age and climate. Here we revisit the issue to identify: (1) how climate and forest age control global forest BD and (2) whether we can set a threshold age for mature forests. Using data from previously published studies we modelled the impacts of forest age and climate on BD using linear mixed effects models. We examined the potential biases in the dataset by comparing how representative it was of global mature forests in terms of its distribution, the climate space it occupied, and the ages of the forests used. BD increased with forest age, mean annual temperature and annual precipitation. Importantly, the effect of forest age increased with increasing temperature, but the effect of precipitation decreased with increasing temperatures. The dataset was biased towards northern hemisphere forests in relatively dry, cold climates. The dataset was also clearly biased towards forests <250 years of age. Our analysis suggests that there is not a single threshold age for forest maturity. Since climate interacts with forest age to determine BD, a threshold age at which they reach equilibrium can only be determined locally. We caution against using BD as the only determinant of forest maturity since this ignores forest biodiversity and tree size structure which may take longer to recover. Future research should address the utility and cost-effectiveness of different methods for determining whether forests should be classified as mature.

Culturally modified trees (CMTs) are trees with scars that reflect human utilization of forested ecosystems. Some CMTs can reveal unique knowledge of native cultures and insight to peoples' subsistence and land use in the past, and are mostly to be found in protected areas since they contain very old trees. In this study, we examine attributes and the spatial and temporal distribution of barkpeeled trees, and present forest structure in two remnant ponderosa pine forests (Pinus ponderosa P. & C. Lawson) in western Montana. We also wanted to use an alternative method of dating CMTs and initiate a broader discussion of threats to such trees and needs for sustaining and protecting them. In total, 343 bark-peelings were recorded on 274 living and dead trees. Our results show that only certain trees were selected for harvest. Nearby trees of similar size and age were not used. The age estimation indicates that the bark-peelings were performed from the mid 1600s until the early 1900s. Today the forest at both study areas is generally low in density and all-aged with very old individual trees. They consist of a mosaic of uneven-aged tree groups and individual trees of various ages. We conclude that the abundance and density of bark-peeled trees at the study areas exceed values reported in most other North American studies (formally protected forests included), that the two areas represent different harvest areas for ponderosa pine inner bark, and that CMTs need to be recognized both as ecologically and culturally valuable features of old ponderosa pine forests.

Eastern North American forests have effectively lost two major tree species (American chestnut and American elm) in the last 100 years and two more, eastern and Carolina hemlock, will be functionally extinct over much of their ranges within a couple of decades. The loss of eastern hemlock is of particular concern because hemlock is:

Because old trees contain centuries of environmental history, investigators are increasingly turning to dendrochronology to create context for current environmental change. While a suite of characteristics to identify old trees has been developed, most of these characteristics are for conifers or trees growing in low-density forests. Given that the diverse Eastern Deciduous Forest (EDF) is dominated by a species-rich, angiosperm-dominated woody flora, old-growth forests are scarce in the EDF, and research permits in natural areas often limit the number of trees that can be sampled, having a suite of characteristics that identify old trees for a wider range of species increases the likelihood of efficiently creating longer depths of ecological history. The common indicators of old (> 250 year old) EDF angiosperms are presented to aid in the recovery and preservation of these living sources of information. Six common external characteristics of old angiosperm trees include: (1) smooth or "balding" bark; (2) low stem taper; (3) high stem sinuosity; (4) crowns comprised of few, large-diameter, twisting limbs; (5) low crown volume; and (6) a low ratio of leaf area to trunk volume. The existence of old trees in the landscape can also be related to life-history traits or land-use histories. Both professionals and lay folk can be trained to identify these traits and environmental conditions. While these characteristics and settings generally signal the potential for old trees, there is no guarantee that they represent old ages. However, these characteristics should aid in the discovery of old trees throughout the EDF.

Tree-ring research has made significant contributions to our understanding of environmental change and forest stand dynamics. Its application to understanding natural history, however, has been limited. Biodiversity of the central hardwood forest offers many opportunities for tree-ring based, natural history research. Recent tree-ring research examining several rarely studied hardwood species has yielded ages well beyond maximum expectations. For example, a sampling of 20 Magnolia acuminata trees in one population included two individuals 315 and 348 years, respectively, which are nearly two centuries more than the average life expectancy reported for this species. Also, research in recently discovered old-growth stands in western Massachusetts has illustrated the common occurrence of Betula lenta in Tsuga canadensis dominated oldgrowth forests with individuals frequently living beyond 320 years in these systems. These studies illustrate that tree-ring research can expand our knowledge of the natural history of central hardwood species.