scholarly journals Initial Responses in Growth, Production, and Regeneration following Selection Cuttings in Hardwood-Dominated Temperate Rainforests in Chile

Forests ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 412
Author(s):  
Pablo J. Donoso ◽  
Patricio F. Ojeda ◽  
Florian Schnabel ◽  
Ralph D. Nyland
Keyword(s):  
Forest Type ◽  
Basal Area ◽  
Tree Regeneration ◽  
Individual Growth ◽  
Evergreen Forest ◽  
South Central ◽  
Tolerant Species ◽  
Shade Tolerant Species ◽  
Temperate Rainforests ◽  
Area And Volume

Hardwood-dominated forests in south-central Chile have shade-tolerant and mid-tolerant tree species capable of regenerating and growing well in partial shade. To test the potential for using an uneven-aged silviculture in these forests, we established single-tree selection treatments at two mid-elevation sites within the Evergreen forest type in the Coastal range (Llancahue and Los Riscos, 40–42° S Lat). They had an average initial basal area of 70–80 m2 ha−1. In each stand, we established four 2000 m2 plots with a residual basal area of ~40 m2 ha−1, and four with a residual basal area of ~60 m2 ha−1. We planned for a maximum residual diameter of 80 cm, but needed to leave 20%–25% of the residual basal area in larger trees due to their great abundance in these old-growth forests. We re-measured these plots 5–6 years after the cuttings. We used mixed-effects models to evaluate the periodic annual increment (pai) in diameter and the abundance of tree regeneration, and linear models to evaluate ingrowth and changes in the basal area and volume. At Llancahue, the diameter pai of individual trees was significantly greater in the treatment with lower residual densities, especially for mid-tolerant species in lower diameter classes (5–20 cm). At both sites, the pai in the stand basal area and volume was greater in the more heavily stocked treatment, but differences were significant only at Llancahue. Regeneration was dominated by shade-tolerant species at both sites but was more abundant and more diverse at Llancahue. Taller tree regeneration (50–<200 cm) significantly increased after the cuttings at both sites, while small regeneration (5–<50 cm) overall remained at pre-cut levels. This pattern was similar for mid- and shade-tolerant species. However, we found no differences in regeneration responses between the lower and higher levels of the residual basal area. Sapling densities did not differ at both sites for shade-tolerant species, but for mid-tolerant species these were more abundant at Los Riscos. While both sites had many similar trends after implementing selection cuts (a greater individual growth in the treatment with lower basal areas but a higher stand-level growth in the treatment with a high basal area, more abundant regeneration of shade-tolerant species, etc.), they illustrate a differential potential for implementing uneven-aged silviculture, especially due to site-species interactions. These results are a first step towards evaluating the prospects for selection cuttings in these experiments and elsewhere in Valdivian temperate rainforests.

Canopy tree growth responses following selection harvest in seven species varying in shade tolerance

2009 ◽  
Vol 39 (2) ◽  
pp. 430-440 ◽  
Author(s):  
Trevor A. Jones ◽  
Grant M. Domke ◽  
Sean C. Thomas
Keyword(s):  
Community Dynamics ◽  
Time Lag ◽  
Species Abundance ◽  
Basal Area ◽  
Maximum Growth ◽  
Forest Community ◽  
Growth Responses ◽  
Canopy Tree ◽  
Tolerant Species ◽  
Shade Tolerant Species

We used tree ring measurements to investigate the temporal response of basal area increment (BAI) of canopy trees following selection harvests by sampling across a chronosequence of stands with known harvest dates in tolerant hardwood (Great Lakes – St. Lawrence) stands in central Ontario. Seven tree species of various shade tolerances ranged widely in their responses to reduced competition. The more shade-tolerant species responded more positively: shade-tolerant species showed an average increase in BAI of 35% 4–15 years postharvest compared with 16% for mid-tolerant species and –7.5% for intolerant species. All species showed a time-lag in postharvest growth responses, with maximum growth responses occurring between 3 and 15 years postharvest. Tree size was the most important factor determining the magnitude of BAI response, with smaller trees consistently responding more than larger trees. We suggest that higher growth responses to selection harvests among shade-tolerant species may contribute to declines in mid-tolerant species abundance in selection-managed stands. More broadly, interspecific variability in canopy tree responses to forest disturbance appears to follow patterns distinct from seedling and sapling responses, with important implications to forest community dynamics in both managed and unmanaged forests.

scholarly journals Trees do not always act their age: size-deterministic tree ring standardization for long-term trend estimation in shade-tolerant trees

2019 ◽  
Vol 16 (24) ◽  
pp. 4815-4827
Author(s):  
Rachel Dietrich ◽  
Madhur Anand
Keyword(s):  
Tree Ring ◽  
Basal Area ◽  
Ring Formation ◽  
Tree Size ◽  
Growth Trend ◽  
Biological Growth ◽  
Tolerant Species ◽  
Tree Ring Data ◽  
Shade Tolerant Species

Abstract. With increasing awareness of the consequences of climate change for global ecosystems, the focus and application of tree ring research have shifted to reconstruction of long-term climate-related trends in tree growth. Contemporary methods for estimating and removing biological growth trends from tree ring series (standardization) are ill-adapted to shade-tolerant species, leading to biases in the resultant chronologies. Further, many methods, including regional curve standardization (RCS), encounter significant limitations for species in which accurate age estimation is difficult. In this study we present and test two tree ring standardization models that integrate tree size in the year of ring formation into the estimation of the biological growth trend. The first method, dubbed size-deterministic standardization (SDS), uses tree diameter as the sole predictor of the growth trend. The second method includes the combined (COMB) effects of age and diameter. We show that both the SDS and COMB methods reproduce long-term trends in simulated tree ring data better than conventional methods; this result is consistent across multiple species. Further, when applied to real tree ring data, the SDS and COMB models reproduce long-term, time-related trends as reliably as traditional RCS and more reliably than other common standardization methods (i.e. C-method, basal area increments, conservative detrending). We recommend the inclusion of tree size in the year of ring formation in future tree ring standardization models, particularly when dealing with shade-tolerant species, as it does not compromise model accuracy and allows for the inclusion of unaged trees.

Partitioning of understorey light and dry-season soil moisture gradients among seedlings of four rain-forest tree species in Madagascar

2007 ◽  
Vol 23 (5) ◽  
pp. 569-579 ◽  
Author(s):  
Roland C. de Gouvenain ◽  
Richard K. Kobe ◽  
John A. Silander
Keyword(s):  
Soil Moisture ◽  
Tree Species ◽  
Light Availability ◽  
Forest Tree ◽  
Dry Season ◽  
Tree Regeneration ◽  
Resource Gradients ◽  
Tolerant Species ◽  
Shade Tolerant Species ◽  
Species Performance

Resource partitioning has been hypothesized to play a role in the maintenance of tree diversity in tropical forests. We looked for evidence of light and soil moisture partitioning among seedlings of four native Malagasy tree species, the pioneer, gap-adapted species Harungana madagascariensis and the three shade-tolerant species Ocotea cymosa, Stephanostegia capuronii and Uapaca ferruginea. Four hundred and eighty seedlings were transplanted in experimental plots in the Tampolo coastal forest and grown for 2 y. Growth rates increased with increasing light availability for all species, and with increasing dry-season soil moisture for H. madagascariensis. With increasing light availability, survival increased for H. madagascariensis, S. capuronii and U. ferruginea but decreased for O. cymosa. While dry-season soil moisture did not influence the growth or survival of the shade-tolerant species, it interacted with understorey light in its effect on the performance of H. madagascariensis, which performed better in wet soils at high light than in dry soils in shade. Rank reversals in species performance suggested that three of the four tree species partition resource gradients as seedlings, mostly light and secondarily dry-season soil moisture. There was only partial agreement between the performance of transplanted seedlings and the distribution of natural seedlings of the same four species with respect to light and soil moisture, suggesting that the success of tropical tree regeneration can only be partly accounted for by seedling performance across resource gradients.

Geostatistically modeling stem size and increment in an old-growth forest

1994 ◽  
Vol 24 (7) ◽  
pp. 1354-1368 ◽  
Author(s):  
Franco Biondi ◽  
Donald E. Myers ◽  
Charles C. Avery
Keyword(s):  
Spatial Patterns ◽  
Growth Rates ◽  
Spatial Dependence ◽  
Basal Area ◽  
Tree Density ◽  
Individual Growth ◽  
Old Growth ◽  
Model Estimate ◽  
Stem Size ◽  
Old Growth Forest

Geostatistics provides tools to model, estimate, map, and eventually predict spatial patterns of tree size and growth. Variogram models and kriged maps were used to study spatial dependence of stem diameter (DBH), basal area (BA), and 10-year periodic basal area increment (BAI) in an old-growth forest stand. Temporal variation of spatial patterns was evaluated by fitting spatial stochastic models at 10-year intervals, from 1920 to 1990. The study area was a naturally seeded stand of southwestern ponderosa pine (Pinusponderosa Dougl. ex Laws. var. scopulorum) where total BA and tree density have steadily increased over the last decades. Our objective was to determine if increased stand density simply reduced individual growth rates or if it also altered spatial interactions among trees. Despite increased crowding, stem size maintained the same type of spatial dependence from 1920 to 1990. An isotropic Gaussian variogram was the model of choice to represent spatial dependence at all times. Stem size was spatially autocorrelated over distances no greater than 30 m, a measure of average patch diameter in this forest ecosystem. Because patch diameter remained constant through time, tree density increased by increasing the number of pine groups, not their horizontal dimension. Spatial dependence of stem size (DBH and BA) was always much greater and decreased less through time than that of stem increment (BAI). Spatial dependence of BAI was close to zero in the most recent decade, indicating that growth rates in 1980–1990 varied regardless of mutual tree position. Increased tree crowding corresponded not only to lower average and variance of individual growth rates, but also to reduced spatial dependence of BAI. Because growth variation was less affected by intertree distance with greater local crowding, prediction of individual growth rates benefits from information on horizontal stand structure only if tree density does not exceed threshold values. Simulation models and area estimates of tree performance in old-growth forests may be improved by including geostatistical components to summarize ecological spatial dependence.

scholarly journals Effects of heavy thinnings on the increment and selection of trees for tending in Norway spruce monoculture in natural hazard conditions

2017 ◽  
pp. 31-54
Author(s):  
Martin Bobinac ◽  
Sinisa Andrasev ◽  
Andrijana Bauer-Zivkovic ◽  
Nikola Susic
Keyword(s):  
Norway Spruce ◽  
Growth Stage ◽  
Natural Hazard ◽  
Basal Area ◽  
Growth Potential ◽  
Stand Age ◽  
Diameter Increment ◽  
Volume Increment ◽  
Selection Of ◽  
Area And Volume

The paper studies the effects of two heavy selection thinnings on the increment of Norway spruce trees exposed to ice and snow breaks in eastern Serbia. In a thinning that was carried out at 32 years of age, 556 candidates per hectare were selected for tending, and at the age of 40, of the initial candidates, 311 trees per hectare (55.9%) were selected as future trees. In all trees at 41-50 age period, diameter increment was higher by 31%, basal area increment by 64% and volume increment by 67% compared to 32-40 age period. The collective of indifferent trees is significantly falling behind compared to future trees in terms of increment values in both observed periods. However, the value of diameter, basal area and volume increments, of the collective of "comparable" indifferent trees are lower in comparison to the values of increments of future trees by 10-15% in the 32-40 age period, and by 15-21% in the 41-50 age period and there are no significant differences. The results show that heavy selective thinnings, initially directed at a larger number of candidates for tending at stand age that does not differ much from the period of carrying out first "commercial" thinnings, improve the growth potential of future and indifferent trees, where it is rational to do the tree replacement for the final crop in "susceptible" growth stage to snow and ice breaks.

scholarly journals Rocky pine forests in the High Coast Region in Sweden: structure, dynamics and history

2020 ◽  
Vol 38 ◽  
pp. 101-130
Author(s):  
Jennie Sandström ◽  
Mattias Edman ◽  
Bengt Gunnar Jonsson
Keyword(s):  
Human Impact ◽  
Fire History ◽  
Dead Wood ◽  
Forest Type ◽  
Basal Area ◽  
Pine Forests ◽  
Small Scale ◽  
Natural Dynamics ◽  
Almost All ◽  
High Degree

Almost all forests in Sweden are managed and only a small fraction are considered natural. One exception is low productive forests where, due to their limited economical value, natural dynamics still dominate. One example is the Scots pine (Pinus sylvestris L.) forests occurring on rocky and nutrient-poor hilltops. Although these forests represent a regionally common forest type with a high degree of naturalness, their dynamics, structure and history are poorly known. We investigated the structure, human impact and fire history in eight rocky pine forests in the High Coast Area in eastern Sweden, initially identified as good representatives of this forest type. This was done by sampling and measuring tree sizes, -ages, fire-scarred trees, as well as dead wood volumes and quality along three transects at each site. The structure was diverse with a sparse layer of trees (basal area 9 m2 and 640 trees larger than 10 cm ha-1) in various sizes and ages; 13 trees ha-1 were more than 300 years old. Dead wood (DW), snags and logs in all stages of decay, was present and although the actual DW (pine) volume (4.4 m3 ha-1) and number of units (53 ha-1) was low, the DW share of total wood volume was 18% on average. Dead wood can be present for several centuries after death; we found examples of both snags and logs that had been dead more than 300 years. Frequent fires have occurred, with an average cycle of 40 years between fires. Most fires occurred between 1500-1900 and many of them (13) during the 1600s. However, fires were probably small since most fire years were only represented at one site and often only in one or a few samples. The rocky pine forests in the High Coast Area are representative of undisturbed forests with low human impact, exhibiting old-growth characteristics and are valuable habitats for organisms connected to sun-exposed DW. Management of protected rocky pine forests may well include small-scale restoration fires and the limited DW volumes should be protected.

scholarly journals Stand-Level Components of a Growth and Yield Model for Nothofagus Mixed Forests from Southern Chile

Forests ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 810
Author(s):  
Sebastian Palmas ◽  
Paulo C. Moreno ◽  
Wendel P. Cropper ◽  
Alicia Ortega ◽  
Salvador A. Gezan
Keyword(s):  
Forest Type ◽  
Geographical Area ◽  
Basal Area ◽  
Forest Growth ◽  
Model Systems ◽  
Growth And Yield ◽  
Permanent Plots ◽  
Stand Age ◽  
Yield Model ◽  
Mixed Forests

Reliable information on stand dynamics and development is needed to improve management decisions on mixed forests, and essential tools for this purpose are forest growth and yield (G&Y) models. In this study, stand-level G&Y models were built for cohorts within the natural mixed second-growth Nothofagus-dominated forests in Chile. All currently available (but limited) data, consisting of a series of stratified temporary and permanent plots established in the complete range of this forest type, were used to fit and validate these models. Linear and nonlinear models were considered, where dominant stand age, number of trees, and the proportion of basal area of Nothofagus species resulted in significant predictors to project future values of stand basal area for the different cohorts (with R2 > 0.51 for the validation datasets). Mortality was successfully modeled (R2 = 0.79), based on a small set of permanent plots, using the concept of self-thinning with a proposed model defined by the idea that, as stands get closer to a maximum density, they experience higher levels of mortality. The evaluation of these models indicated that they adequately represent the current understanding of dynamics of basal area and mortality of Nothofagus and companion species in these forests. These are the first models fitted over a large geographical area that consider the dynamics of these mixed forests. It is suggested that the proposed models should constitute the main components of future implementations of G&Y model systems.

scholarly journals Growth After Thinning a 35-Year-Old Natural Stand to Different Loblolly Pine and Hardwood Basal Areas

1997 ◽  
Vol 21 (4) ◽  
pp. 168-174
Author(s):  
Michael G. Shelton ◽  
Paul A. Murphy
Keyword(s):  
Loblolly Pine ◽  
Block Design ◽  
Volume Growth ◽  
Basal Area ◽  
Timber Production ◽  
Product Class ◽  
Randomized Complete Block Design ◽  
Timber Products ◽  
Total Growth ◽  
Area And Volume

Abstract Growth was monitored for 4 yr in a thinned stand in southern Arkansas with three pine basal areas (70, 85, and 100 ft2/ac) and three hardwood basal areas (0, 15, and 30 ft2/ac); pretreatment basal areas averaged 119 and 33 ft2/ac for pines and hardwoods, respectively. Treatments were arranged in a 3 X 3 factorial randomized complete block design with three replicates, yielding 27 permanent 0.20 ac plots. Growth variables were regressed with residual pine and hardwood basal areas. Pine basal area and volume growth increased with the pine stocking level after thinning and decreased with the level of retained hardwoods. For basal area and merchantable volume, hardwood growth largely compensated for losses in the pine component, and thus, hardwood retention had little net effect on the total growth of the stand. The greatest impact of hardwood retention was on the stand's sawtimber growth, because hardwoods did not contribute to this product class. Each 1 ft2/ac of retained hardwood basal area reduced pine sawtimber growth by 6 to 10 bd ft Doyle/ac/yr, depending on the pine stocking. Because large differences existed in the value of timber products, retaining 15 and 30 ft2/ac of hardwoods reduced the value of timber production by 13 and 24%, respectively, at 4 yr after thinning. South. J. Appl. For. 21(4):168-174.

scholarly journals Severity of Overstory Mortality Influences Conifer Recruitment and Growth in Mountain Pine Beetle-Affected Forests

Forests ◽  
2018 ◽  
Vol 9 (9) ◽  
pp. 536 ◽  
Author(s):  
Kristen Pelz ◽  
Charles Rhoades ◽  
Robert Hubbard ◽  
Frederick Smith
Keyword(s):  
High Mortality ◽  
Mountain Pine Beetle ◽  
Lodgepole Pine ◽  
Basal Area ◽  
Tree Regeneration ◽  
Forest Recovery ◽  
Subalpine Fir ◽  
Advance Regeneration ◽  
Mountain Pine ◽  
Pine Beetle

The severity of lodgepole pine mortality from mountain pine beetle outbreaks varies with host tree diameter, density, and other structural characteristics, influencing subcanopy conditions and tree regeneration. We measured density and leader growth of shade-intolerant lodgepole pine, shade-tolerant Engelmann spruce, and very shade-tolerant subalpine fir regeneration beneath stands that experienced moderate and high overstory lodgepole pine mortality (average 40% and 85% of total basal area) a decade earlier. Lodgepole comprised >90% of the overstory basal area and mature spruce and fir were present in both mortality levels, though live basal area and disturbance history differed. Post-beetle outbreak recruitment was high in both mortality levels, but there were more lodgepole in high than moderate mortality plots (1140 stems ha−1 vs. 60 stems ha−1) and more subalpine fir in moderate than high mortality plots (4690 stems ha−1 vs. 2870 stems ha−1). Pine advance regeneration, established prior to outbreak, was more dense in high mortality than moderate mortality sites (930 stems ha−1 vs. 310 stems ha−1), but the trend was generally the opposite for the other conifers. Lodgepole recruitment increased and subalpine fir decreased with greater forest floor light availability. All species grew faster in high mortality areas than their counterparts in moderate mortality areas. However, in high mortality areas pine grew faster than the more shade tolerant species, and in moderate mortality areas spruce and fir grew faster than pine. These species-specific responses to the degree of overstory mortality will influence future stand composition and rate of forest recovery after mountain pine beetle outbreaks.

scholarly journals Long-Term Effects of Fuels Treatments, Overstory Structure, and Wildfire on Tree Regeneration in Dry Forests of Central Washington

Forests ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 888
Author(s):  
Allison K. Rossman ◽  
Jonathan D. Bakker ◽  
David W. Peterson ◽  
Charles B. Halpern
Keyword(s):  
Prescribed Burning ◽  
Basal Area ◽  
Tree Regeneration ◽  
Dry Forest ◽  
Permanent Plots ◽  
Long Term Effects ◽  
Fuels Reduction ◽  
Forest Fuels ◽  
Fuels Treatments

The long-term effectiveness of dry-forest fuels treatments (restoration thinning and prescribed burning) depends, in part, on the pace at which trees regenerate and recruit into the overstory. Knowledge of the factors that shape post-treatment regeneration and growth is limited by the short timeframes and simple disturbance histories of past research. Here, we present results of a 15-year fuels-reduction experiment in central Washington, including responses to planned and unplanned disturbances. We explore the changing patterns of Douglas-fir regeneration in 72 permanent plots (0.1 ha) varying in overstory abundance (a function of density and basal area) and disturbance history—the latter including thinning, prescribed burning, and/or wildfire. Plots were measured before treatment (2000/2001), soon afterwards (2004/2005), and more than a decade later (2015). Thinning combined with burning enhanced sapling recruitment (ingrowth) into the overstory, although rates of ingrowth were consistently low and greatly exceeded by mortality. Relationships between seedling frequency (proportion of quadrats within a plot) and overstory abundance shifted from weakly negative before treatment to positive after thinning, to neutral in the longer term. However, these relationships were overshadowed by more recent, higher-severity prescribed fire and wildfire that stimulated seedling establishment while killing advanced regeneration and overstory trees. Our results highlight the dependence of regeneration responses on the history of, and time since, fuels treatment and subsequent disturbance. Managers must be aware of this spatial and temporal complexity and plan for future disturbances that are inevitable but unpredictable in timing and severity.

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