scholarly journals Seed Availability Does Not Ensure Regeneration in Northern Ecosystems of the Endangered Limber Pine

Forests ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 146 ◽  
Author(s):  
Vernon S. Peters ◽  
Darcy R. Visscher
Keyword(s):  
Seed Production ◽  
Abiotic Factors ◽  
A Priori ◽  
Production Capacity ◽  
Basal Area ◽  
Forest Composition ◽  
Theoretic Approach ◽  
Limber Pine ◽  
Seed Availability ◽  
Pine Regeneration

Research Highlights: When biotic interactions such as disease alter both the seed production capacity of stands, and seedling survivorship, the relative importance of seed availability versus substrate specificity may alter future regeneration opportunities for plant populations. Background and Objectives: We investigated the importance of disease severity, seed availability, and substrate limitation to the regeneration dynamics of the endangered limber pine, Pinus flexilis, in two ecosystems with varying forest composition, and different histories of white pine blister rust infection (WPBR; Cronartium ribicola). Materials and Methods: A total of 17 stands from the montane ecoregion (Alberta, Canada) were sampled for seed production between 2007–2010, seedling density, and age structure. Model selection using an information theoretic approach compared a series of a priori models and their combinations, based on our hypotheses on the role biotic variables play in the regeneration process. Results: Despite higher rates of WPBR infection, 2.3 times more seed was available for avian dispersers in the southern ecosystem. Recent seedling regeneration did not correspond to seed production (83 versus 251 seedlings/ha, in southern versus northern ecosystems, respectively), resulting in a seven-fold difference in seed to seedling ratios between ecosystems. Models suggest that disease and vegetation cover were important factors explaining the absence of regeneration in 79.4% of the plots sampled, while basal area (BA) of live limber pine, rocky substrates, ecosystem, South aspects, and slope enhanced limber pine regeneration. Seedling age structures suggest that recent regeneration is less likely in more diseased landscapes, than it was historically (40% versus 72.8% of seedlings < 20 years old, respectively, in southern versus northern ecosystems). Conclusions: At the northern limits of limber pine’s range, seed availability does not ensure regeneration, suggesting that other environmental or biotic factors hinder regeneration. Regeneration was consistently predicted to be lower in the southern ecosystem than in the northern ecosystem, suggesting that natural regeneration and the potential for population recovery are ecosystem dependent. We recommend that monitoring recent seedlings will aid the identification of biotic and abiotic factors affecting regeneration.

scholarly journals Landscape condition influences energetics, reproduction, and stress biomarkers in grizzly bears

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Abbey E. Wilson ◽  
Dan Wismer ◽  
Gordon Stenhouse ◽  
Nicholas C. Coops ◽  
David M. Janz
Keyword(s):  
Protein Expression ◽  
Physiological Function ◽  
A Priori ◽  
Food Resources ◽  
Information Criteria ◽  
Complement C3 ◽  
Grizzly Bears ◽  
Theoretic Approach ◽  
Protein Food ◽  
The Impact

AbstractEnvironmental change has been shown to influence mammalian distribution, habitat use, and behavior; however, few studies have investigated the impact on physiological function. This study aimed to determine the influence of landscape condition on the expression of target proteins related to energetics, reproduction, and stress in grizzly bears. We hypothesized that changes in landscape condition explains protein expression. Skin biopsies were collected from free-ranging grizzly bears in Alberta, Canada from 2013–2019 (n = 86 individuals). We used an information theoretic approach to develop 11 a priori candidate generalized linear mixed models to explain protein expression. We compared models using Akaike Information Criteria (AICc) weights and averaged models with ΔAICc < 2 for each protein. Food resources, represented by increased distance to coal mines and decreased crown closure, positively influenced energetic proteins (adiponectin and alpha-1-acid glycoprotein). Proteins related to reproduction (ceruloplasmin and serpin B5) were positively associated with increased wetland and upland food resources in addition to movement, but negatively associated with increased distance to roads. One stress related protein, complement C3, was positively influenced by increased percent conifer. Given the need to detect emerging threats to wildlife, we suggest the assessment of physiological function will lead to improved monitoring of species in rapidly changing landscapes.

THE SEED PRODUCTION CAPACITY AND EFFICIENCY OF RED PINE CONES (PINUS RESINOSA AIT.)

1956 ◽  
Vol 34 (1) ◽  
pp. 27-36 ◽  
Author(s):  
L. A. Lyons
Keyword(s):  
Seed Production ◽  
Production Efficiency ◽  
Production Capacity ◽  
Pinus Resinosa ◽  
Proximal Part ◽  
Red Pine ◽  
First Year ◽  
Tree Crown ◽  
Second Year ◽  
Pine Cones

The seed capacity of red pine cones varies from about 30 to over 110, depending on the size of the cone and its position in the tree crown, and is determined by the number of ovules that are structurally complete at the time of pollination. These ovules occur in a central "productive" region and constitute less than one-half of the total. The remaining ovules, most: of which are in the proximal part of the cone, never become structurally perfect, and do not contribute to seed production. Abortion of ovules in the productive region usually reduces seed production efficiency to 50–60%, and is accompanied mainly by withering of the nucellus in the first year and failure to produce archegonia early in the second year. The extent of ovule abortion during the first year varies indirectly with cone size, seed capacity, and height in tree.

Insects Affecting Seed Production in Red Pine: IV. Recognition and Extent of Damage to Cones

1957 ◽  
Vol 89 (6) ◽  
pp. 264-271 ◽  
Author(s):  
L. A. Lyons
Keyword(s):  
Seed Production ◽  
Production Capacity ◽  
Red Pine ◽  
Natural Control ◽  
Present Contribution ◽  
Southern Ontario ◽  
Pine Cone ◽  
Poor Seed ◽  
Extent Of Damage ◽  
Cone Damage

The broad study of factors responsible for poor seed production by red pines (Pinus resinosae Ait.) in central and southern Ontario has been concerned with the seed production capacity and efficiency of sound cones (1) and the description, life history, behaviour, and natural control of cone-inhabiting insects (2, 3, 4). The present contribution, which concludes the four-part series on red pine cone insects, deals with the time and duration of cone attack by the various insect species and the variability in the intensity of cone damage from year to year and from one locality to another. As an aid to the field diagnosis of the cause of cone damage, keys based on the appearance of mature larvae and injured cones are included.

Long-Term Development of Regeneration Under Longleaf Pine Seedtree and Shelterwood Stands

1993 ◽  
Vol 17 (1) ◽  
pp. 10-15 ◽  
Author(s):  
William D. Boyer
Keyword(s):  
Seed Production ◽  
Seedling Establishment ◽  
Longleaf Pine ◽  
Basal Area ◽  
Pinus Palustris ◽  
Stand Density ◽  
Distribution Characteristic ◽  
Volume Increment ◽  
Potential Impact

Abstract Well-stocked mature longleaf pine (Pinus palustris Mill.) stands were cut to five residual basal areas in 1957, namely 9, 18, 27, 36, and 45 ft² per ac, to observe the effect of stand density on seed production and seedling establishment. Seedlings, mainly from the 1955 or 1961seed crops, were established in treated stands. All pines on net 0.9 ac plots were remeasured in 1991 to determine the effect of residual pine density on development of the regeneration. Even the lightest residual overstory converted the structure of 29- to 35- yr-old ingrowth into the reverse-Jdiameter class distribution characteristic of uneven-aged stands. Four or six residual trees, now comprising 7 to 10 ft² basal area (ba)/ac, reduced ingrowth basal area to about half that of same-aged stands released from overstory competition. Merchantable volume of ingrowth under theselow residual densities averaged 40% of that in released stands. Mean annual per ac volume increment of ingrowth averaged 21 to 22 ft³ under the 9 ft² density but did not exceed 7 ft³ under any residual density above this. The potential impact of significant growth reductionsshould be taken into account when considering uneven-aged management methods for longleaf pine. South. J. Appl. For. 17(1):10-15.

scholarly journals Forest Compositional Changes after a Decade of Emerald Ash Borer

Forests ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 949
Author(s):  
Jordan M. Marshall
Keyword(s):  
Emerald Ash Borer ◽  
Basal Area ◽  
Ecological Impacts ◽  
Plant Succession ◽  
Invasive Pest ◽  
Forest Composition ◽  
Green Ash ◽  
Insect Communities ◽  
Compositional Changes ◽  
Understory Trees

Emerald ash borer is an invasive pest in North American forests. Ecological impacts of ash mortality from emerald ash borer are wide-ranging, including shifts in insect communities and wildlife behavior. Additionally, loss of ash from forests may have important implications regarding plant succession. Surveys of overstory, midstory, and understory trees within forests in northeastern Indiana, Lower Peninsula of Michigan, and northwestern Ohio were conducted to quantify the change in forest composition over a 10 year period. Interpolation of ash dominance illustrated inversion of live and dead ash values between 2007 and 2017. Even though more than 83% of overstory live ash basal area was lost across the study area, green ash was the most abundant midstory and understory species representing regeneration. Additionally, loss of ash from many of the sites resulted in compositional changes that were greater than merely the subtraction of ash. Due to the relatively large number of forest types with which ash species are associated, loss of ash will have broad ecological consequences, including on community composition.

A 10-Year Evaluation of Prescribed Winter Burns in Uneven-Aged Stands of Pinus-Taeda L and P. Echinata Mill - Woody Understorey Vegetation Response

1993 ◽  
Vol 3 (1) ◽  
pp. 13 ◽  
Author(s):  
MD Cain
Keyword(s):  
Pinus Taeda ◽  
Prescribed Burning ◽  
Basal Area ◽  
Vegetation Response ◽  
Understorey Vegetation ◽  
Single Tree ◽  
Pine Regeneration ◽  
Single Tree Selection ◽  
Pinus Taeda L

The effects of burning cycles and pine basal area levels were assessed on natural pine regeneration and hardwood development in uneven-aged stands of loblolly and shortleaf pines (Pinus taeda L. and P. echinata Mill.). The treatments included an unburned control and prescribed winter burns at 3-, 6-, and 9-yr intervals. Basal area treatments were 9, 14, 18, and 23 m2 ha-1 for the merchantable-pine component and were maintained on a 6-yr cutting cycle using single-tree selection. Ten years after the study was initiated, density and quadrat stocking of pine regeneration were negatively correlated with overstorey basal area. The 6-yr burning cycle had higher pine density and better quadrat stocking of pine regeneration compared with any other bum treatment mainly because the 6-yr burning cycle coincided with a bumper pine seedcrop and the 6-yr cutting cycle. Recurring fires tended to result in reduced size of hardwood competition but had less impact on hardwood density. When considering a prescribed burning program in uneven-aged stands of loblolly and shortleaf pines, more attention should be given to density, quadrat stocking, and size of established pine regeneration and to expected seedcrops rather than to the prosecution of rigid burning schedules.

Effects of Sheep Grazing Astrebla Grasslands in Central Western Queensland. Iii. Dynamics of Astrebla Spp. Under Grazing and Exclosure Between 1975 and 1986.

1991 ◽  
Vol 13 (1) ◽  
pp. 36 ◽  
Author(s):  
DM Orr ◽  
CJ Evenson
Keyword(s):  
Population Dynamics ◽  
Seed Production ◽  
Basal Area ◽  
Summer Rainfall ◽  
High Variability ◽  
Plant Population ◽  
Sheep Grazing ◽  
Plant Population Dynamics ◽  
Winter Rainfall ◽  
Plant Populations

The basal area, yield and plant populations of Astrebla spp. were monitored under grazing and exclosure in Astrebla grasslands between 1975 and 1986. This study was undertaken to develop an understanding of how Astrebla spp. respond to grazing, particularly in relation to the high variability of rainfall. Basal area and yield of Astrebla spp. varied widely between years in response to summer rainfall, with few differences between exclosure and grazing. The failure of summer rainfall resulted in increased utilization of Astrebla spp. but this effect was partially offset in some years by the growth of forb species following winter rainfall. Grazing stimulated the recruitment of Astrebla spp. seedlings by increasing the density of inflorescences which, in turn, increased seed production. Survival of seedling cohorts depended on adequate summer rainfall and grazing tended to enhance cohort survival. There was a greater plant flux under grazing than under exclosure. It was concluded that rainfall is the major factor influencing the biomass and plant population dynamics of Astrebla spp. and that grazing up to about 30% utilization is not detrimental to Astrebla spp.

scholarly journals Vegetative and Fruit Resources as Determinants of Habitat use by Mature-Forest Birds During the Postbreeding Period

The Auk ◽  
2007 ◽  
Vol 124 (2) ◽  
pp. 494-507 ◽  
Author(s):  
Andrew C. Vitz ◽  
Amanda D. Rodewald
Keyword(s):  
Vegetation Structure ◽  
A Priori ◽  
Forest Birds ◽  
Canopy Height ◽  
Theoretic Approach ◽  
Mature Forest ◽  
Risk Of Predation ◽  
Structure Density ◽  
Information Theoretic Approach ◽  
Capture Rates

AbstractRecent studies have demonstrated that many birds of mature forests heavily use early-successional habitat during the postbreeding period. Two frequently invoked hypotheses to explain these shifts are that postbreeding birds select (1) dense cover to reduce risk of predation and (2) abundant fruit resources to facilitate foraging. Using mist nets between 15 June and 16 August in 2002 and 2003, we captured mature-forest birds during the postbreeding period in 12 regenerating hardwood clearcuts (three to seven years old) in southeast Ohio. Vegetation structure and fruit resources were measured at nine net locations within each clearcut. We applied an information-theoretic approach, where we used vegetative and fruit variables as predictors in seven a priori models to evaluate how habitat factors might explain capture rates. In two seasons, we captured 1,089 hatch-year (HY) and 445 after-hatch-year (AHY) postbreeding birds of 32 mature-forest species. In general, models reflecting habitat structure (density of low vegetation, canopy height) best explained variation in capture rates, which were negatively related to the density of low vegetation (<1.5 m) and positively related to canopy height. Extremely dense low vegetation may be disadvantageous if it inhibits movements and provides cryptic locations for ground predators. Instead, habitats with greater vertical structure (e.g., taller vegetation) and relatively less dense low vegetation below may provide better protection from aerial and ground predators. Overall, results suggest that vegetation structure may explain high use of early-successional forests by many birds during the postbreeding period, though fruit may be the most important factor for seasonal frugivores.Recursos Vegetativos y de Frutos como Determinantes del Uso de Hábitat por Aves de Bosque Maduro Durante el Período Posterior a la Reproducción

scholarly journals Twentieth-century shifts in forest structure in California: Denser forests, smaller trees, and increased dominance of oaks

2015 ◽  
Vol 112 (5) ◽  
pp. 1458-1463 ◽  
Author(s):  
Patrick J. McIntyre ◽  
James H. Thorne ◽  
Christopher R. Dolanc ◽  
Alan L. Flint ◽  
Lorraine E. Flint ◽  
...  
Keyword(s):  
Forest Structure ◽  
Forest Biomass ◽  
Basal Area ◽  
Hydrologic Model ◽  
Forest Composition ◽  
Demographic Shift ◽  
Small Tree ◽  
Breast Height ◽  
Large Tree ◽  
Climatic Water Deficit

We document changes in forest structure between historical (1930s) and contemporary (2000s) surveys of California vegetation through comparisons of tree abundance and size across the state and within several ecoregions. Across California, tree density in forested regions increased by 30% between the two time periods, whereas forest biomass in the same regions declined, as indicated by a 19% reduction in basal area. These changes reflect a demographic shift in forest structure: larger trees (>61 cm diameter at breast height) have declined, whereas smaller trees (<30 cm) have increased. Large tree declines were found in all surveyed regions of California, whereas small tree increases were found in every region except the south and central coast. Large tree declines were more severe in areas experiencing greater increases in climatic water deficit since the 1930s, based on a hydrologic model of water balance for historical climates through the 20th century. Forest composition in California in the last century has also shifted toward increased dominance by oaks relative to pines, a pattern consistent with warming and increased water stress, and also with paleohistoric shifts in vegetation in California over the last 150,000 y.

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