Accordingly, the growth efficiency index is recognized as a reliable tree vigor index [ 13 ] and has been successfully used to study tree mortality [ 12 ] and stand dynamics [ 14 ]. Because calculation of the growth efficiency index requires estimation of tree leaf area, it is difficult to use it for retrospective tree force evaluations. The growth-based index that was best related to both growth efficiency index and tree strength classes was then used to quantify its temporal changes between two qualitative determinations of tree strength class.
Conclusions
Guillemette, F.; Bedaard, S.; Havreljuk, F. Taux de mortalité des feuillus selon la priorité de récolte; Direction de la recherche forestière : Québec, QC, Canada, 2015 ; P. Grondin, P.; John, N.; Hotte, D. Intégration de la végétation et de ses variables explicatives pour la classification et la cartographie des unités homogènes du sud du Québec ; Direction de la recherche forestière : Québec, QC, Canada, 2007 ; P. Boulet, B. Défauts externes et signes de pourriture des arbres ; Les Publications du Québec : Québec, QC, Canada, 2007 ; P
Short-Term Vegetation Responses to Invasive Shrub Control Techniques for Amur Honeysuckle
Lonicera maackii [Rupr.] Herder)
Introduction
Few studies have investigated the effects of mulching head treatments on understory plant communities or compared their effects to those of stump treatments, and none have examined the individual and interactive effects of substrate disturbance and mulch deposition of this technique on plant recovery. distinguish plant communities. Amur honeysuckle is a strong candidate for investigating the effectiveness of mulch head treatments and their effects on understory flora due to its tendency to form dense thickets [23]. We also expected that soil disturbance from the mulch head treatment would increase honeysuckle seedling densities and garlic mustard cover, but that these effects would be mitigated by mulch deposition.
Methods
The primary objective of this study was to investigate how understory plant communities respond to honeysuckle removal using mulch head treatments compared to the currently recommended cut-stump method. Removal methods were randomly assigned to each four-field grouping (e.g., upper left black square) to avoid incidental effects of the mulching head on non-targeted fields. We took four measurements of mulch thickness at each mulch head treatment plot prior to mulching manipulations and attempted to replicate the highest average depth of 2.5 cm across all mulch plots.
Results
Native seedling J decreased in the reference areas during the study and increased after the brush removal treatment (Fig. 4d). Densities (a) and diversity indices (b–d) of native woody species before invasive brush removal (2015) and after brush removal using stump cutting or forestry mulch head (“MH”) treatments with mulch removed/absent added /present. Floristic Quality Index (FQI) for understory communities, including exotic species, before (2015) and after (2016 and 2017) invasive shrub removal was obtained using stump cutting or Forestry Mulch Head ("MH") treatments, with was mulch removed/absent or added/present.
Discussion
Re-establishment of Chinese privet was also higher in areas treated with a mulching head in riparian forests in Georgia, USA [ 16 ]. The mulching head probably disturbs the litter layer on the forest floor more than the rock stump method, which can increase the germination and establishment of both honeysuckle and garlic mustard seedlings [20]. The increase in garlic mustard cover was similar between treatments, despite greater honeysuckle cover in mulching heads.
Testing undergrowth responses to mulching head in combination with strategies to further mitigate regrowth, including increased tillage intensity, spring treatment, and use of follow-up control methods, will help elucidate how the pulse of forge regeneration after mulching head treatment responds to lower regrowth densities. of germinated mature specimens. Overall, recovery of native plant communities was similar between the two treatment methods, despite greater regrowth of sedge after the mulching head treatment. If the study had followed only the effects of brush removal for one growing season after treatment, the effects of mulching on native seedling density, the stronger responses of sagebrush seedling density in mulched plots, and the negative effects of mulching on spring perennial diversity would indicate that mulching is less suitable for achieving restoration goals as the cut-storage method.
Although mulch deposition had no statistically significant effects on native plant community recovery in this study, there were consistent trends of mulch with effects opposite those of the mulch head removal method alone, which may account for the similar responses observed between operational mowing. −]and MH[+]treatments (Table 4). Native plant community responses were similar between the mulch head and cutting stump treatments and the increase in Amur honeysuckle seedlings following the mulch head treatment was largely transient. Although the mulching head treatment in this study was slightly less effective than the cutting stump method in preventing honeysuckle regrowth, our results indicate that greater treatment depth with the mulching head may reduce shrub volume after treatment.
Habitat-specific resilience of the invasive shrub Amur honeysuckle (Lonicera maackii) during repeated clipping. Ecol.
The Potential Distribution of Tree Species in Three Periods of Time under a Climate Change Scenario
Materials and Methods
In each model, variables that explained 70% or more of the data variability in principal component analysis (PCA) [30,37] were included. In contrast, the smallest absolute coefficients (three of them negative) were observed between the most recent glacial period and the contemporary period, and between the largest period. Possible areas of distribution of Pinus species for the last ice age (21,000 years ago), the present and the future period (2080-2100).
This was more evident for the first two species between the period of the most recent glaciation and the contemporary period (Figure 4). Considering that the actual interval of climate tolerance (optimal interval) is variable between one species and another, although they live together in the same region [26], it is possible that there were overestimations of the models. Moreover, in the SMO there are no studies on the actual anthropogenic effects, as this may accelerate the change of the natural distribution of some species.
For example, when comparing the corresponding values for the present period and the future period for both Quercus magnolifoli and Q. Conversely, a weak correlation was observed between the values from the past and present period for both Quercus crassifoli and Quercus arizonica (Table 3). The potential ranges of most of the species did not vary between periods.
The critical role of available area in ecological niche modeling and species distribution modeling.
Recent Trends in Large Hardwoods in the Pacific Northwest, USA
Such perspectives are rooted in the understanding that very frequent fires (recurring within 15 years) occurred before Euro-American colonization in many forest areas due to combinations of natural ignition and Native American burning [30,31]. Based on the review of potential indicators above, we hypothesized that declines in the basal area of large trees would be greatest in the shade-intolerant black oak and white oak, which are dependent on frequent fires. Over 40% of the basal area of the eight species was located in the Klamath ecoregion, with the Sierra Nevada (18.3%), California Coast (17%), and California Coast Range (16.6%) ecoregions also important.
Basal area for each species across the ecoregions during time 2 is included in the supplementary materials (Table S1). Tanoak was the most dominant hardwood species in the coastal ecoregions, while black oak and live oak were dominant in the Sierra Nevada. Although not statistically significant, mean black oak basal area decreased in the California Coast Range, Sierra Nevada, and Klamath, and many of those deaths in those areas were attributed to fire.
Meanwhile, mean black oak basal area increased in the Cascades, where fire mortality was relatively low. Other regions contributed little to the black oak basal area. The basal Tanoak area had negligible subsidence on the Oregon coast. For example, analysis of three periods showed a decline in the basal area of very large black oaks, while the overall basal area was relatively stable.
Because understory shrubs can intensify wildfires in white oak forests [57] and potentially in other hardwood stands, site preparation to reduce oak mortality may include treatments to reduce shrub continuity and promote grasses or other herbaceous species that facilitate the spread of low-intensity fire [ 11]. Escaping the socioecological trap through tribal stewardship of national forests in the Pacific Northwest, USA.Ecol. Responses of California black oak to fire severity and invasion of native conifers in the Klamath Mountains.
Effect of Predation, Competition, and Facilitation on Tree Survival and Growth in Abandoned Fields
Towards Precision Restoration
One third of the tree seedlings were planted directly into the herbaceous vegetation (VG), which was less than 20 cm tall at the time of planting. In rows between seedlings with bare soil, vegetation was cut with the weed cutter to prevent herbaceous vegetation exceeding 20 cm in height. Herbaceous biomass and light (%PPFD) were compared only between herbaceous vegetation and mulch mat subplots with ANOVAs.
Species Mortality Due to Predators Dead Seedlings (Fall 2012) % Dead Seedlings (Spring 2015) Bare Soil Mulch Mat Herbaceous Vegetation Total Unprotected Protected. No effect of herbaceous vegetation was observed on maraca diameter, but maraca seedlings growing in bare soil were smaller than those surrounded by cover or in herbaceous vegetation, after the former (F-test = 9.7673 ; p = 0.0118) and the second (F -test = 13.4052; p =0.0061) growing seasons (Figure 2a). After five years, the survival of all pioneer species seedlings growing in herbaceous vegetation was higher than 75%, with the exception of paper birch (Figure 3a).
Herbaceous vegetation increased the mortality of four hardwood species (Table 2), while the growth of all hardwood species was negatively affected by competition (Figure 2). Survival and growth of conifer species were not negatively affected by herbaceous vegetation (tolerance), while positive effects were observed on survival and height growth of tamarack seedlings. Tamarack is one of the species (along with red pine) that has a low specific root length (SRL) [58].
Tree species can be considered tolerant to herbaceous vegetation if they have a high survival rate, even if growth is reduced, because many seedlings will eventually outgrow the vegetation layer [5,63]. Thus, we suggest that conifers and red ash are tolerant to herbaceous vegetation because they had a high survival rate (>75%) and a height increase of more than 50 cm after five years. Survival, growth and photosynthesis of tree seedlings competing with herbaceous vegetation along a water-light-nitrogen gradient. Plant Ecol.
