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1.
Insects respond to changes in microhabitat caused by canopy disturbance, and thus can be used to examine the ecological impacts of harvesting. Single-tree selection harvesting is the most common silvicultural system used to emulate local small-scale natural disturbance and maintain uneven-aged forest structure in temperate forests. Here, we test for differences in richness, abundance, and composition of hymenopteran and saproxylic insect assemblages at four different taxon levels (selected insect orders; and all hymenopteran families, and braconid subfamilies and morphospecies) between the canopy and understory of unharvested and single-tree selection harvested sites in a northern temperate forest from central Canada. Harvesting had no effect on insect assemblage richness, composition or abundance at the three highest taxon levels (order, family and subfamily). Similarly, richness and abundance at the lowest-taxon level (braconid morphospecies) were similar, although composition differed slightly between unharvested and harvested stands. Insect assemblages were vertically stratified, with generally higher abundance (for Diptera, Hymenoptera, some hymenopteran families and braconid subfamilies) and richness (for braconid morphospecies) in the understory than the canopy. In particular, composition of the braconid morphospecies assemblage showed relatively low similarity between the understory and canopy. Single-tree selection harvesting appears to influ-ence wood-associated insect taxa only subtly through small changes in community composition at the lowest taxon level, and thus is recommended as a conservative approach for managing these northern temperate forests. 相似文献
2.
We studied the effects of partial cutting on understory vegetation communities within 19 mixed maple forests in an agriculture-dominated landscape in southwestern Ontario. Woodlots that had been recently harvested were grouped according to provincial silviculture guidelines (standard and heavy cuts) and compared to woodlots that had been uncut for at least 24 years (reference stands). We found significant differences in richness, diversity, and quality of understory vegetation in response to harvest indices. More intensive harvesting resulted in increased richness and diversity, but mostly through the addition of habitat generalists and weedy species. However, partial harvest does not appear to drive vegetation community composition, as ordination methods found no clear community differences between the treatments. Use of the single-tree selection system based on basal area and harvest intensity targets will have an effect on the understory plants, but other factors including past management, disturbance history, and site level microclimate features will also play an important role in shaping vegetation communities. We caution against the removal of large volumes of trees ≥38 cm in diameter, and large reductions in canopy cover, as this can reduce the presence of “conservative” (forest dependent specialist) species, despite a general increase in species richness and diversity. Furthermore, we recommend additional research to investigate the potential for incremental degradation to occur on sites with a long-term history of harvesting, as we found that richness of exotics increased on sites with a history of forest management. 相似文献
3.
We used a before-after, control-impact design (one year pre-harvest, two years post-harvest) and unlimited-radius point counts to study the effects of typical group-selection harvesting (0.5 gaps ha−1 placed near seed trees within a standard single-tree selection harvest) and intensive group-selection harvesting (4 gaps ha−1 placed on a grid with no harvesting between gaps) on the composition and abundance of breeding birds in tolerant hardwood forests in Algonquin Provincial Park, Ontario. Percent similarity between pre- and post-harvest bird communities was 5–9% lower in selection harvested stands than in reference stands. Differences in percent similarity among the three treatments were not significant, however, suggesting that the changes in the bird community in stands harvested with group selection were not substantially different than those in reference stands. Abundance of aerial foragers and tree-and-shrub nesters increased in response to typical and intensive group selection in the second year post-harvest. By contrast, bark foragers and cavity-nesters decreased in the first year post-harvest and then increased in the second year post-harvest in response to typical group selection. Abundance of 16 (73%) of 22 species was not affected by harvesting. Blue Jay (Cyanocitta cristata), Chestnut-sided Warbler (Dendroica pensylvanica), Least Flycatcher (Empidonax minimus), and White-throated Sparrow (Zonotrichia albicollis) increased in response to intensive group selection in the first or second year post-harvest, whereas Chestnut-sided Warbler, Hairy Woodpecker (Picoides villosus), and White-throated Sparrow increased in response to typical group selection in the first or second year post-harvest. Ovenbird (Seiurus aurocapilla) decreased slightly in response to typical group selection in the second year post-harvest. Our short-term data suggest that intensive, rather than typical, group-selection harvesting is preferred for maintaining densities of cavity-nesting birds and Ovenbird; whether these advantages continue through the remainder of the cutting cycle and beyond requires further investigation. 相似文献
4.
We studied the effects of six levels of dispersed green-tree retention (GTR) harvesting (clearcut (0%), 10%, 20%, 50%, and 75%, and unharvested reference (100%)) on understory plant communities in the 8th growing season post-harvest in the mixedwood boreal forest in northwestern Alberta. For the partial harvest treatments (10%, 20%, 50%, 75%) sample plots were located in the partially harvested (retention) strips as well as in the intervening machine corridors used by the harvesting equipment. The understory plant community was significantly influenced by the gradient of retention level. The cover of understory vegetation, especially graminoids, increased with increasing harvesting intensity for the retention strips and overall considering both plots types. Species richness was unaffected by retention level but did decrease as tree density increased. Lower levels of retention lead to increased abundance of early successional, shade-intolerant species. The results suggest a threshold in understory response to GTR harvesting between the 10% and 20% retention treatments. In terms of understory cover and composition, machine corridors within partially harvested forests resembled clearcuts. The results suggest that retaining more than 10% during GTR harvesting could have significant benefits in terms of maintaining understory plant communities more similar to unharvested reference forest. 相似文献
5.
Daniel F. R. Cleary 《Journal of Sustainable Forestry》2017,36(8):806-817
In the present study, the impact of logging was assessed on the forest structure, richness, and composition of trees, lianas, and ground herbs in Indonesian Borneo. There were no significant differences in tree height, diameter, basal area, or abundance between unlogged and logged forest. Liana abundance was higher in logged than unlogged forest, but the difference was marginally nonsignificant. There was also no significant difference in the percentage cover of ground herbs. Tree species richness was similar between unlogged and logged forest, while liana species richness was higher in logged forest and herb species richness between unlogged forest. Tree and liana compositions differed significantly between unlogged and logged forest, but logging explained only a small part (<7%) of the variance in composition. In contrast to trees and lianas, ground herb composition did not differ significantly between unlogged and logged forest. Our findings indicate that the modest extraction intensity practiced did not have a severely adverse impact on forest structure or plant composition. This highlights the important role that logged forests may play in conserving biodiversity and the need to protect these forests from further disturbance. 相似文献
6.
Christel C. Kern Brian J. Palik Terry F. Strong 《Forest Ecology and Management》2006,230(1-3):162-170
We evaluated ground-layer plant diversity and community composition in northern hardwood forests among uncut controls and stands managed with even-age or uneven-age silvicultural systems. Even-age treatments included diameter-limit cuttings (20-cm diameter at 30-cm stem height) in 1952 and shelterwood removals in 1964. Uneven-age treatments included three intensities of selection harvest (light, 20.6 m2/ha residual basal area after harvest; medium, 17.2 m2/ha residual basal area; and heavy, 13.8 m2/ha residual basal area) that were applied in 1952, 1962, 1972, and 1982. All treatments were winter logged over snow pack. In 1991, plant diversity and community composition were examined. Species richness for spring ephemerals ranged from 1 to 6 species/150-m2, spring ephemeral diversity (Shannon's Index of Diversity) averaged 0.57 ± 0.04 and evenness averaged 0.45 ± 0.03. Summer flowering species richness ranged from 1 to 18 species/1-m2, with an average diversity of 0.71 ± 0.07 and evenness of 0.42 ± 0.03. We found no significant differences among treatments for any of these variables, although power to detect a difference (at p = 0.05) was low in all cases (0.15–0.55) due to high variance and low replication. Community composition was not significantly different among the treatments, for either spring (p = 0.09) or summer (p = 0.79) flora. Few exotic species were found in any treatment. Lack of exotic invasions and minimal differences in plant diversity or composition among treatments may be due, in part, to the negligible amount of soil disturbance that resulted from winter logging. While other (unmeasured) ecosystem components may differ among these silvicultural treatments, our results suggest that ground-layer plant communities in northern hardwood ecosystems are either resistant to change or have recovered within the 40 years since disturbance in the even-age treatments and within 10 years since disturbance in the uneven-age treatments. 相似文献
7.
8.
The immediate effects of bioenergy harvesting methods on epixylic species were studied in mature managed Norway spruce dominated forests in southern Finland. The treatments included logging, residue harvesting, and soil preparation as either mounding or mounding combined with stump harvesting. Altogether, 110 logs and 440 species sample plots on logs were inventoried before and after logging, and after soil preparation treatments. Logging decreased the cover and species richness in all epixylic species groups. The soil preparation decreased the cover of macrolichens, while stump harvesting was significantly most devastating both for cover and richness in bryophytes. We suggest that bioenergy harvesting critically affects the epixylic species, and therefore the use of less devastating methods and compensation for the loss of coarse woody debris is recommended on a landscape level. 相似文献
9.
Disturbance is a key factor affecting plant species richness and it has been hypothesized that species richness reaches a peak some time after disturbance occurs. Managed boreal forests are characterized by large scale disturbance in the form of clear-cuttings, which partly resembles natural disturbance regimes. The young stands however, which may be important to many plants, are often homogenous and dense compared to naturally regenerated stands. We examined previously unstudied effects of disturbance, succession and management practices on plant species richness in boreal forests. Survey data covering the northern and central parts of Sweden (4465 plots) were used to compare species richness and composition in four stand maturity classes—“cutting”, “young”, “pre-mature” and “mature”, and two fertility classes—“rich” and “poor”. In addition, the effect of thinning was examined in young and pre-mature forests. 相似文献
10.
《林业研究》2021,32(4)
Understanding the effects of disturbance on seed rain is critical to predict changes in forest species composition and diversity.Logging effects on seed rain in a mixed conifer-hardwood forest complex in southern Brazil were evaluated.One year of seed rain data were collected from a large-scale observational experiment in logged and protected forests and quantity and average seed size weighted by species abundance(CWM) were compared between old-growth and logged stands 55 years after logging activities.Using these data,variations in frequency of functional groups of species in the seed rain were examined to see if they could be attributed to logging.Results show that the number of seeds per trap was highly right-skewed,ranging from 13 to 12,788 seeds per trap in one year.Seed rain was affected by logging history,with seed traps in old-growth plots receiving significantly less seeds than traps in logged plots.All species included mean seed size weighted by species abundance were significantly smaller in logged than in old-growth forests.This difference persisted after the exclusion of Arawcaria a large-seeded pioneer which was intensively logged,although the difference of seed size between the two forest classes was greatly reduced.Species abundance in the seed rain differed significantly from the established tree community,between logged and oldgrowth stands.The composition of the seed rain was much more variable than the composition of the established tree community and its points more scattered over the ordination space than the points corresponding to the protected forests.The number of collected seeds across different functional groups of species significantly differed between logged and old-growth plots.The seed rain of logged forests reflects their arrested succes sion as indicated by reduced abundance of functional groups such as pioneers,large seeded pioneers and A raucaria,as well as reduced functional diversity.S eed rain differences between logged and old-growth stands reflect the intensive logging of A.angustifolia. 相似文献
11.
A vegetation survey of semi-permanent plots was conducted between years 1955–1962 and 2005–2009, and aimed to determine floristic changes occurring in beech forests located on a scarcely populated, dense forest area. The survey encompassed all natural beech forest types within the Polish part of the “Eastern Carpathians” International Reserve of Biosphere. A comparison of trends in changes between unmanaged (Bieszczady National Park) and managed (the remaining part of the Biosphere Reserve) forests was attempted. DCA analysis was used for the determination of changes on the community level. The density of vegetation, species richness, frequency of occurrence and cover, and functional groups of species were determined. Much more profound community changes were determined to have occurred in managed beech forests. However, a similar direction in vegetation changes within both managed and unmanaged forests verifies the existence of a regional pattern of changes in beech forests. This regional pattern involves (1) a decrease in the shares of arborescent species within the shrub layer, (2) disturbance of the canopy layer, (3) acidification of the top layer of the soil, (4) change of light conditions, (5) increase in shares of generalist species and decrease in shares of specialist species. A decreasing anthropogenic pressure, aging of forest stands, functioning of large, dense forest areas and sustainable forest management strategies forestry management system mimicking natural deciduous forest disturbance regime constitute factors shaping the regional changes of the forest vegetation. The undergoing changes can lead to biotic and spatial homogenization of the Eastern Carpathian beech forests. 相似文献
12.
Coert J. Geldenhuys 《Journal of Forest Research》2010,15(1):3-13
How can we accommodate the diversity in tree species and sizes in mixed-species/size/age stands in the sustainable management of natural forests and woodlands in Africa for diverse timber and non-timber forest products and services, and during rehabilitation of degraded forests? The evergreen moist tropical to warm-temperate forests, from the equator to 34°S, generally function through relative shade tolerance. The tropical, strongly seasonal, drier deciduous woodlands generally function through adaptation to fire and/or grazing/browsing. Silvicultural systems, when implemented, are often not aligned with the ecological characteristics of the particular forest systems or the specific targeted species. This paper presents the concept of using the basic disturbance–recovery processes, with recovery development via stand development stages, as the basis for the development of silvicultural systems suitable for maintenance of forest complexity. Grain analysis and stem diameter distributions, analysed from resource inventories, are used to determine the specific shade- or fire-tolerance characteristics of key economical and ecological tree species. The gained knowledge of the ecosystem and species characteristics (including modes of regeneration, i.e. from seed or vegetative regrowth) and processes is used to simulate the ecological disturbance–recovery processes through the development of mixed silvicultural systems, such as a single-tree selection system, a group felling system and a coppice management system in the same forest. Very similar concepts are used to develop rehabilitation strategies to recover the processes towards regrowth stands of diverse species and structure: through stands of introduced plantations and invader tree species; and through early regrowth stages in deciduous woodlands and evergreen forests, after fire, slash-and-burn traditional agriculture, charcoal production or open-cast mining. 相似文献
13.
《林业研究》2019,(6)
Biodiversity has become an issue of global attention because of growing awareness of its importance and its rapid depletion worldwide. Diversity of tree species in relation to environmental and disturbance gradients was examined in three managed forests. Trees were randomly sampled in a survey of 75 circular plots(radius = 13 m)with 5 subplots(radius = 1 m). Generalized linear model analysis was used with a Poisson distribution log link function to understand the effects of variables(organic matter, organic carbon, nitrogen, potassium, pH, elevation and disturbance) on tree species richness. Canonical correspondence analysis was used to explore ecological relationships among plots. Our result found that the stand characteristics was an important influencing factor in the three forests. Our result showed that the variables had a highly positive influence on tree species richness in the three forests. In ordination, the selected variables governed the richness of tree species. Our study can help identify the most important factors that drive tree species richness in the three managed forests in Bangladesh and in similar ecosystems and inform forest management decisions for conservation according to ecological importance. 相似文献
14.
Todd E. Ristau 《Forest Ecology and Management》2011,262(6):970-979
Shelterwood seed cutting in conjunction with herbicide site preparation has proven effective at regenerating Allegheny hardwood forests, but the long-term impact of this silvicultural system on herbaceous vegetation has not been determined. From 1994 to 2004, we studied the impacts of operational herbicide site preparation using glyphosate plus sulfometuron methyl herbicides in the context of a shelterwood seed cut. Our study took place on 10 partially cut sites on the Allegheny National Forest in northwestern Pennsylvania. Half of each site received herbicide and half did not in a split-plot design with repeated measures. Fences were erected after year six because deer impact had increased. Resilience of individual species and the community were determined using measures of percent cover by species or species groups and indices of diversity and similarity comparing post-treatment to pre-treatment conditions and controls. In the short term, abundance of all species was reduced and there were four fewer species on average in treated areas. No species was eliminated by herbicide across all sites in the long term. Graminoids were more abundant on treated plots after year six. Targeted ferns remained less abundant on treated than control plots after 10 years. Species richness recovered within 4 years following treatment. Shannon Diversity and Shannon Evenness were greater in treated than in control plots over the full study period, but the differences were not significant in any single year. The richness-based Jaccard index of similarity did not differ between control and treatment plots after year two, while relative abundance influenced indices showed significant differences through year eight. Results suggest that herbaceous layer vegetation is resilient to the disturbance created by herbicide-shelterwood treatments. 相似文献
15.
Natalia Kuznetsova Aksinya Gomina Olga Smirnova Mikhail Potapov 《European Journal of Forest Research》2018,137(5):659-674
Unique 600-year-old tall herb taiga forests are located in the European North-East of Russia at the foothills of the Middle Urals and are characterized by extremely diverse and vertically differentiated vegetation. This study addresses how vegetation parameters such as net primary productivity and diversity influence the community structure of Collembola in fir forests of different ages. Sample plots were arranged along diversity and biomass gradients of vegetation: Vaccinium-moss, short herb-moss, and nitrophilous tall herb fir–spruce forests. Plants and collembolans were compared with respect to their species richness, abundance, species structure and traits. The number of species of vascular plants, mosses and liverworts along the studied gradient increased by about double, whereas the species richness of collembolans did not differ significantly. The biomass of vascular plants increased, whereas that of mosses declined, and the abundance of collembolans remained approximately consistent. Despite sharp differences in ground vegetation, in all phytocenoses the dominant Collembola species were widespread. However, the collembolan community of old-growth tall herb forests showed a trend of more complex structure reflected by greater evenness of abundances compared to younger ecosystems with less diverse ground vegetation. In conclusion, the springtail communities in forests that have developed spontaneously for over 600 years appeared to be no more complex than those in 200-year-old stands. Multi-species ground vegetation did not increase collembolan diversity and abundance indices. Thus, soil mesofauna (in this case, springtails) appeared to be relatively independent of long-term spontaneous development in vegetation in the studied area. 相似文献
16.
Ewa Stefańska-Krzaczek Wiesław Fałtynowicz Bartłomiej Szypuła Zygmunt Kącki 《European Journal of Forest Research》2018,137(4):419-431
In Central Europe, deciduous forests are the dominant community type and lichen pine forests are restricted to certain areas with extremely nutrient-poor and xeric soil types. In recent decades, a retreat of vegetation of oligotrophic habitats has been observed in Central Europe. In this study, we assessed changes of lichen pine forests in Poland: within the main area of the range in Central Europe. We used two sets of data collected at a local and regional (nation-wide) scale. On the basis of data from semi-permanent plots, we examined changes in the structure and species composition of lichen pine forests over 33 years at the local scale (between 1975 and 2008). To compare trends at the regional scale, we used data collected in the Polish Vegetation Database (PVD). For identification of lichen pine forests we determined a group of co-occurring Cladonia species. We analyzed differences in species richness and vegetation structure at the regional scale in tree time periods (1) between 1951 and 1969, (2) 1970 and 1989, and (3) 1990 and 2011. We found that changes in lichen pine forests are primarily quantitative at both scales. Our results indicate that the abundance of Cladonia species is limited by strong competitors, i.e., vascular plants and bryophytes, which may be explained by eutrophication and climate warming. Only pine forests with a minor abundance of lichens have chances to persist in the vegetation of Central Europe, while the most valuable communities with high abundance of indicators will disappear. Though an assessment of the total decrease in the area of lichen pine forests is not possible with the available regional data, local observations indicate a large decline in the area of lichen pine forests in Central Europe. Their conservation seems to be a serious challenge, because it is difficult to provide optimal conditions for all indicators. 相似文献
17.
We examined patterns of variation in richness, diversity, and composition of understory vascular plant communities in mixedwood boreal forests of varying composition (broadleaf, mixedwood, conifer) in Alberta, Canada, before and for 2 years following variable-retention harvesting (clearcut, 20 and 75% dispersed green tree retention, control). Broadleaf-dominated forests differed from mixedwood or conifer-dominated forests in that they had greater canopy cover, litter depth, soil nitrogen, warmer soils, as well as greater shrub cover, herb and shrub richness and diversity (plot scale). In contrast, conifer, and to a lesser extent mixedwood, forest had greater β diversity than broadleaf forest. Overall, mixedwood and conifer forests were similar to one another, both differed from broadleaf forest. Several species were found to be significant indicators of broadleaf forest but most of these also occurred in the other forest types. Understory composition was related to canopy composition and edaphic conditions. Variable-retention harvesting had little effect on understory cover, richness, or diversity but resulted in reduced richness and β diversity at a larger scale. The clearcut and 20% treatments affected composition in all forest types. Early successional species and those common in disturbed sites were indicators of harvesting while evergreen, shade-tolerant understory herbs were indicators of the control forest and 75% retention harvest. We conclude that it is important to maintain a range of variation in canopy composition of mixedwood forests in order to conserve the associated understory communities. The presence of conifers in these forests has a particularly important influence on understory communities. The threshold for a lifeboat effect of variable-retention harvesting is between 20 and 75% retention. Examination of richness and β diversity at a variety of scales can provide interesting information on effects of harvesting on spatial reorganization and homogenization of understory plant communities. 相似文献
18.
Kathryn Corio Amy Wolf Michael Draney Gary Fewless 《Forest Ecology and Management》2009,258(7):1059-1066
The invasion of exotic earthworms in previously earthworm-free northern deciduous forests has been linked to the disappearance of forest floor litter, declines in plant species richness, and the development of monotypic stands of Carex pensylvanica. However, the impact of exotic earthworms on the regeneration of trees and understory plants is largely unknown. We examined the relationships between earthworm density, plant species richness, leaf litter accumulation, number of tree (Acer) seedlings, and cover of C. pensylvanica at 14 sites in mesic hardwood forests of the Chequamegon-Nicolet National Forest in northern Wisconsin. Earthworm biomass, especially of the genera Lumbricus, Aporrectodea, and Octolasion was negatively associated with leaf litter mass and number of Acer seedlings. Nine plant species, including two spring ephemerals (Dicentra cucullaria and Osmorhiza claytonii), a sedge (Carex deweyana), and an invasive mint (Galeopsis tetrahit) were negatively correlated with exotic earthworm densities. Dryopteris intermedia and Allium tricoccum, on the other hand, were associated with high earthworm densities. The activities of exotic earthworms appear to have significant impacts on Acer regeneration and the persistence of many herbaceous plants. Our findings suggest that the effects of exotic earthworms on litter mass are strongly related to the observed effects on species composition. Sensitive species can be used as indicators of high and low earthworm densities and might be useful for identifying forests of high conservation value where future invasions of exotic earthworms should be prevented. 相似文献
19.
《Forest Ecology and Management》2004,190(1):33-41
Liana (woody vine) abundance varies among tropical forests and is often high in disturbed forests. In two areas of subtropical wet forest in Puerto Rico, El Verde and Bisley, we recorded the density of liana stems ≥1 cm dbh, and the percent of tree crowns (trees ≥10 cm dbh) that lianas infested. Both study areas have been disturbed by hurricanes several times in the past century; however, sample plots in each area were divided between plots that were less disturbed and those that were more disturbed, by both hurricanes and humans. The mean density and basal area of liana stems at El Verde were significantly higher in the less disturbed plots than in the more disturbed plots. The percent tree crown infested by lianas was higher on certain tree species and on larger trees, both of which characterized the less disturbed forest. Results at Bisley were similar to those at El Verde. Liana density and tree crown infestation in these Puerto Rican forests were low compared with most other tropical forests, contrasting especially with high values in other disturbed forests. Liana abundance varies among forests for complex reasons, including differences in disturbance, biogeography, seasonality, and tree host features. 相似文献
20.
Ecological investigation of the distribution and composition of dung beetle species utilizing feces of wild mammals has rarely
been attempted, especially in cool-temperate forests. In this study we recorded and evaluated the community structure of dung
beetle species utilizing feces of Japanese monkeys (Macaca fuscata) by conducting a macro-scale inventory survey in the northeastern Shirakami Mountains, located in the northernmost part of
mainland Japan. Moreover, to assess the effect of human-induced forest disturbance on species assemblages in this cool-temperate
area, we also carried out field sampling using pitfall traps baited with monkey feces in primary forests, secondary forests,
and coniferous plantations, during every season except winter. Our findings were: (1) 14 dung beetle species comprising eight
dwellers and six tunnelers utilized monkey feces; (2) Aphodius eccoptus was the core species in dung beetle assemblages attracted to the feces during spring and summer; (3) the frequency of occurrence
of every species was extremely high in spring; and (4) human-induced forest disturbance did not increase species richness
or biomass in cool-temperate forests. 相似文献