Does old-growth condition imply high live-tree structural complexity?

2004 ◽  
Vol 195 (1-2) ◽  
pp. 243-258 ◽  
Author(s):  
Eric K Zenner
Keyword(s):  
Growth Condition ◽  
Structural Complexity ◽  
Old Growth ◽  
Live Tree

scholarly journals Differentiating mature and old-growth forests in the Upper Foothills and Subalpine Subregions of west-central Alberta

2003 ◽  
Vol 79 (3) ◽  
pp. 602-612 ◽  
Author(s):  
Luigi E Morgantini ◽  
John L Kansas
Keyword(s):  
Forest Management ◽  
Growth Index ◽  
Tree Height ◽  
Tree Age ◽  
Old Growth ◽  
West Central ◽  
Decay Class ◽  
Management Area ◽  
Growth Attributes ◽  
Live Tree

Weyerhaeuser Company Ltd. is developing harvest strategies that will maintain appropriate levels of late to very late seral stages ("old growth") in its Drayton Valley Forest Management Area. This management area encompasses 490 570 ha in the Foothills and Rocky Mountain Natural Regions of west-central Alberta. In planning for future forest landscapes, Weyerhaeuser intends to maintain a range of age structures consistent with the ecological processes characteristic of each natural region and subregion. The absence of a discrete point separating mature forest from old growth means that the age at which a stand is currently identified as "old growth" and subject to special management practices is arbitrary. In a research study initiated in the summer of 2000, we seek to understand the differences in structure and composition between forests of various ages and topographic site conditions (elevation, aspect, and slope angle). Using 95 sampling plots in a 123-km2 study area in the Upper Foothills and Subalpine Natural Subregions, we quantified vegetation structure and composition for stands ranging in age from 70 to 300 years. Variables measured and analysed included live-tree height and diameter, snag density, diameter and decay class, downed woody material volume, diameter and decay class, vascular plant species richness, sapling and regeneration density, and duff depth. An old-growth index was developed for each sampled stand that took into account multiple attributes. Preliminary results indicate that specific attributes (snag basal area and density, decay stage and density of downed woody material, variation in live-tree age, and variation in live-tree height and age) separate a younger forest from a more mature one and hence may describe "old-growth" conditions. The age of onset of these old-growth attributes is variable but appears to occur between 160 and 180 years. Key factors other than stand age that contribute to or modify the development of old-growth attributes (as measured by the old-growth index) are elevation and moisture regime (as modified by site position). Further investigation is required to more accurately assess the effect of site factors on old-growth attributes. These results are now used by Weyerhaeuser to address retention of late seral stages in long-term forest planning. Key words: old growth, mature forests, old growth protection, forest management, Alberta, Weyerhaeuser, Rocky Mountains foothills

scholarly journals Distribution of epiphytic macrolichens in relation to remnant trees in a multiple-age Douglas-fir forest

1999 ◽  
Vol 29 (8) ◽  
pp. 1204-1215 ◽  
Author(s):  
Stephen C Sillett ◽  
Matthew N Goslin
Keyword(s):  
Pacific Northwest ◽  
Douglas Fir ◽  
Managed Forests ◽  
Old Growth ◽  
Clear Cutting ◽  
Rotation Periods ◽  
Green Algal ◽  
Lobaria Oregana ◽  
Live Tree ◽  
Old Trees

Alternatives to clear-cutting are being implemented to increase biodiversity of managed forests in the Pacific Northwest. Lichens are an integral component of old growth, but lichen biomass develops slowly in forests. We evaluated the long-term potential of live tree retention for lichen conservation in Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) forests. We sampled lichen litterfall in a 2-ha stand that contained 200- to 600-year-old remnant trees scattered in a forest composed mostly of 100-year-old trees that established following fire. We used association, principal components, and regression analyses to relate lichen litterfall biomass to the proximity of remnant trees. Two epiphytic lichens were strongly associated with remnant trees: the foliose cyanolichen Lobaria oregana (Tuck.) Müll. Arg. and the fruticose green algal lichen Sphaerophorus globosus (Hudson) Vainio. Biomass of both species was highest near remnant trees, and biomass was slightly higher within groves of remnant trees than it was at the edges of these groves or near isolated trees. Lichens appear to have persisted on remnant trees through the last fire and are slowly recolonizing younger trees from this source of propagules. Retention of live trees, maintenance of hardwoods, and longer rotation periods have great potential to maintain old-growth-associated lichens in at least some managed forests.

Long-term patterns in the decay, collapse, and abundance of trees with hollows in the mountain ash (Eucalyptus regnans) forests of Victoria, southeastern Australia

2010 ◽  
Vol 40 (1) ◽  
pp. 48-54 ◽  
Author(s):  
David B. Lindenmayer ◽  
Jeff T. Wood
Keyword(s):  
Population Dynamics ◽  
Structural Complexity ◽  
Time Dependent ◽  
Old Growth ◽  
Eucalyptus Regnans ◽  
Southeastern Australia ◽  
Large Trees ◽  
Mountain Ash ◽  
Over Time

Large trees with hollows are an important component of stand structural complexity worldwide. Understanding their population dynamics is needed to manage cavity-dependent biota. We quantified long-term rates of collapse of 302 measured trees with hollows in 1939-aged regrowth mountain ash ( Eucalyptus regnans F. Muell.) forest in southeastern Australia. We identified time-dependent dynamics in which the collapse rates of trees slowed from ∼4% annually between 1983 and 1993 to ∼2.2% between 1993 and 2007. Transitions of trees between different decay states (forms) also slowed over time. Nevertheless, during the 24-year period of our study, over half of our marked and measured trees had fallen, but there was no recruitment of new trees with hollows. Under current projections, few trees with hollows will occur on our field sites by ∼2050, although more had been forecast in earlier investigations. Such a paucity of trees with hollows in extensive areas of regrowth mountain ash forests will lead to a shortage of nesting and sheltering sites for cavity-dependent biota. We suggest a short–medium (10- to 100-year) focus on the conservation of old growth and multi-aged stands will be needed to maintain populations of those species strongly associated with trees with hollows in mountain ash forests.

Crown structure of old-growth Douglas-fir in the western Cascade Range, Washington

2001 ◽  
Vol 31 (7) ◽  
pp. 1250-1261 ◽  
Author(s):  
Hiroaki Ishii ◽  
Megan E Wilson
Keyword(s):  
Structural Complexity ◽  
Douglas Fir ◽  
Cascade Range ◽  
Old Growth ◽  
Crown Structure ◽  
Branch Biomass ◽  
Size Variability ◽  
Branch Density ◽  
Branch Size ◽  
Epicormic Branches

Crown structure of old-growth Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) is characterized by low live-branch density, numerous dead branches and epicormic branches, high branch-size variability, and large gaps in the crown. These features define structural complexity of the crown and create variable crown microenvironments. For the 60 m tall, 400-year-old Douglas-fir trees measured in this study, number of live branches decreased and dead branches increased from the upper to lower crown. Dead branches were found below the lowest live branch indicating that crown recession had occurred. Live-branch biomass culminated at 45 m and decreased markedly below 35 m. Numerous vertical gaps between branches occurred below 40 m. Epicormic branches accounted for 14.6–47.5% of the total number of live branches per tree and contributed to increased crown depth. Epicormic branches filled inner regions of the crown, and contributed to increased branch-size variability. A model of crown structure developed for young trees could be fit to the upper crown of the study trees but could not be applied to the middle to lower crown because of increased branch-size variability. Relative levels of photosynthetically active radiation in the crown decreased with decreasing height, but a local peak occurred around 35–40 m, coinciding with the height of marked decrease in live-branch biomass.

scholarly journals The Role of Canopy Cover Dynamics over a Decade of Changes in the Understory of an Atlantic Beech-Oak Forest

Forests ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 938
Author(s):  
Mercedes Valerio ◽  
Ricardo Ibáñez ◽  
Antonio Gazol
Keyword(s):  
Species Composition ◽  
Temperate Forests ◽  
Light Availability ◽  
Structural Complexity ◽  
Understory Vegetation ◽  
Permanent Plots ◽  
Oak Forest ◽  
Gap Dynamics ◽  
Gap Formation ◽  
Old Growth

The understory of temperate forests harbour most of the plant species diversity present in these ecosystems. The maintenance of this diversity is strongly dependent on canopy gap formation, a disturbance naturally happening in non-managed forests, which promotes spatiotemporal heterogeneity in understory conditions. This, in turn, favours regeneration dynamics, functioning and structural complexity by allowing changes in light, moisture and nutrient availability. Our aim is to study how gap dynamics influence the stability of understory plant communities over a decade, particularly in their structure and function. The study was carried out in 102 permanent plots (sampled in 2006 and revisited in 2016) distributed throughout a 132 ha basin located in a non-managed temperate beech-oak forest (Bertiz Natural Park, Spain). We related changes in the taxonomical and functional composition and diversity of the understory vegetation to changes in canopy coverage. We found that gap dynamics influenced the species composition and richness of the understory through changes in light availability and leaf litter cover. Species with different strategies related to shade tolerance and dispersion established in the understory following the temporal evolution of gaps. However, changes in understory species composition in response to canopy dynamics occur at a slow speed in old-growth temperate forests, needing more than a decade to really be significant. The presence of gaps persisting more than ten years is essential for maintaining the heterogeneity and stability of understory vegetation in old-growth temperate forests.

Trees dying standing in the northeastern boreal old-growth forests of Quebec: spatial patterns, rates, and temporal variation

2007 ◽  
Vol 37 (1) ◽  
pp. 50-61 ◽  
Author(s):  
Tuomas Aakala ◽  
Timo Kuuluvainen ◽  
Louis De Grandpré ◽  
Sylvie Gauthier
Keyword(s):  
Temporal Variation ◽  
Spatial Patterns ◽  
Tree Mortality ◽  
Abies Balsamea ◽  
Structural Complexity ◽  
Habitat Diversity ◽  
Old Growth ◽  
Dead Trees ◽  
Old Growth Forests ◽  
Standing Trees

Spatial patterns, rates, and temporal variation of standing-tree mortality were studied in unmanaged boreal old-growth forests of northeastern Quebec. The study was carried out by sampling living and dead trees within 15 transects (400 m long, 40 m wide). The transects lay in stands that were classified according to their species composition in three types: dominated by black spruce, Picea mariana (Mill.) BSP; mixed P. mariana and balsam fir, Abies balsamea (L.) Mill.; and dominated by A. balsamea. Spatial patterns were analysed using Ripley's K function. The year of death was cross-dated using 190 sample discs extracted from dead standing A. balsamea and P. mariana to assess the rates and temporal variation of mortality. The spatial patterns of standing dead trees in P. mariana stands were predominantly clustered. The spatial patterns of large dead trees (>19 cm diameter at breast height (1.3 m height; DBH)) in mixed and A. balsamea-dominated stands were mainly random, with few stands showing clustered patterns. Small dead trees (9–19 cm DBH) in these stands were generally more clustered than larger trees. Tree mortality varied from year to year, though some mortality was observed in all the studied stand types for almost every year. Standing trees that had recently died accounted for 62%, 48%, and 51% of overall mortality in P. mariana-dominated, mixed, and A. balsamea-dominated stands, respectively. The results of this study indicate that mortality of standing trees outside of episodic mortality events (such as insect outbreaks) is an important process in the creation of structural complexity and habitat diversity in these stands.

scholarly journals Structural heterogeneity and old-growthness: A first regional-scale assessment of Sardinian forests

2020 ◽  
Vol 63 (2) ◽  
pp. 103-120
Author(s):  
Sergio Fantini ◽  
◽  
Mauro Fois ◽  
Paolo Casula ◽  
Giuseppe Fenu ◽  
...  
Keyword(s):  
Species Composition ◽  
Regional Scale ◽  
Structural Complexity ◽  
Canopy Cover ◽  
Structural Heterogeneity ◽  
Mediterranean Forests ◽  
Forest Stands ◽  
Old Growth ◽  
Tree Species Composition ◽  
Growth Features

Mediterranean forests have been altered by several human activities. Consequently, relatively intact forests that have been unmodified by humans for a relatively long time (i.e., old-growth forests) are often reduced to isolated and fragmented stands. However, despite their high conservation value, little is known about their features and even presence several Mediterranean areas. First steps of their investigation are based on the identification of old-growth features such as amount of large‐size and old trees, tree species composition, canopy heterogeneity, occurrence and amount of deadwood. The Structural Heterogeneity Index (SHI) is commonly used to summarise features of old-growthness in one single value. Here, the SHI was derived for 68 plots included in 45 forest stands within the 4,297 km2 of territory that is covered by forests in Sardinia. SHI values were affected by variables that are likely to be related to forest age and structural complexity, such as presence of cerambycids, canopy cover, forest layers, location and three old-growthness classes. Results confirm a high structural variability among forests with old-growth features, determined by the presence, or lack, of given living and deadwood features. Our findings identified, for the first time, most of the forest stands that need special protection in Sardinia for the presence of old-growth features. In this sense, the SHI was confirmed useful for improving their management and conservation, although more specific and deeper studies are necessary for better understanding their species composition and dynamics.

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