Common and Uncommon Understory Species Differentially Respond to Restoration Treatments in Ponderosa Pine/Douglas-Fir Forests, Montana

Restoration treatments have been widely advocated to address declining conditions in Pinus ponderosa forests throughout the western United States. However, few studies have examined treatment effects on individual plant species or whether responses differ for common species and uncommon species (those with low abundance in the community)—information that may be critical in managing for long‐term biodiversity. We investigated understory species responses to restoration treatments in ponderosa pine/Douglas‐fir forests using a randomized block experimental design with three blocks and four treatments (control, burn‐only, thin‐only, and thin‐burn). Understory vegetation was sampled before treatment and for three consecutive years after treatment. We used richness and an index of uniqueness to compare responses of common and uncommon native understory species among treatments, and indicator species analysis to identify individual species that responded to each treatment. Treatments that included thinning had significantly more unique species assemblages than the control. The thin‐only treatment increased common native species richness, whereas all active treatments significantly increased uncommon native species richness over the control, especially the thin‐burn. Generally, life‐forms did not explain the responses of individual species, though in the final sampling year several graminoids were exclusively indicative of treatments that included thinning. Very few species had reduced abundance in the thinning and burning treatments by the final sample year, whereas many uncommon and short‐lived species benefited from active treatments, especially the combined thin‐burn treatment. Active restoration treatments in these forests may foster plant diversity by minimally impacting common species while significantly benefiting disturbance‐dependent native species.     

Managing Non-Native Plant Populations Through Intensive Community Restoration in Cades Cove, Great Smoky Mountains National Park, U.S.A.

Abstract Cades Cove, Great Smoky Mountains National Park, U.S.A. was historically cleared largely for pastoral purposes; it is now comprised of recently abandoned pastures dominated by non‐native pasture species. To investigate the potential for reducing non‐native species relative to native species, park managers initiated an experiment in 1995 that included mowing, herbicide application, planting of seed, and burning of replicate 20 × 50–m plots at each of two sites within Cades Cove. Between 1995 and 2001 we evaluated the response of the plant community (i.e., species‐specific cover and frequency, biomass, diversity) to this suite of treatments and compared it with unmanipulated control plots at each site. Four years after treatment initiation abundance measures of Plantago lanceolata, Setaria geniculata, and Trifolium spp. averaged one‐third lower in treated than control plots. Frequency of Festuca pratensis was lower in treated than in control plots for 2 years, but after 4 years its frequency, cover, and biomass did not differ between treated and control plots. By 2000 the cover of Sorghastrum nutans in treated plots increased to 23–47%, depending on the site. Total biomass and diversity increased in treated plots. The dominance of Lespedeza cuneata at one site apparently reduced planting success, biomass production, and diversity and evenness. Post‐treatment lags in response for several species, coupled with interannual variation in response to environmental conditions, suggest that evaluations of treatment success would differ greatly depending on when the evaluation was conducted.     

A Historical Perspective and Future Outlook on Landscape Scale Restoration in the Northwest Wisconsin Pine Barrens

The concurrent discussions of landscape scale restoration among restoration ecologists, and of historic disturbance pattern as a guideline for forest management among forest scientists, offer a unique opportunity for collaboration between these traditionally separated fields. The objective of this study was to review the environmental history, early restoration projects, and current plans to restore landscape patterns at broader scales in the 450,000 ha northwest Wisconsin Pine Barrens. The Pine Barrens offer an example of a landscape shaped by fire in the past. In northwestern Wisconsin historically the barrens were a mosaic of open prairie, savanna, and pine forests on very poor, sandy soils. The surrounding region of better soils was otherwise heavily forested. Six restoration sites have been managed since the middle of this century using prescribed burns to maintain the open, barrens habitat. However, these sites are not extensive enough to mimic the shifting mosaic of large open patches previously created by fire. Extensive clear‐cuts may be used as a substitute for these large fire patches so that presettlement landscape patterns are more closely approximated in the current landscape. We suggest that such silvicultural treatments can be suitable to restore certain aspects of presettlement landscapes, such as landscape pattern and open habitat for species such as grassland birds. We are aware that the effects of fire and clear‐cuts differ in many aspects and additional management tools, such as prescribed burning after harvesting, may assist in further approximating the effect of natural disturbance. However, the restoration of landscape pattern using clear‐cuts may provide an important context for smaller isolated restoration sites even without the subsequent application of fire, in this formerly more open landscape.     

Effects of the emerald ash borer invasion on the community composition of arthropods associated with ash tree boles in Maryland,U.S.A.

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Dynamics of the exotic Daphnia lumholtzii and native macro-zooplankton in a subtropical chain-of-lakes in Florida, U.S.A.

1. Seasonal dynamics of the exotic Daphnia lumholtzii and native macro-zooplankton species were studied for 2 years in six inter-connected lakes in Florida, U.S.A. The lakes ranged widely in pH, colour and trophic status, and were dominated by copepods.
2. All six lakes contained both D. lumholtzii and the native D. ambigua , but the two species did not overlap in time. D. ambigua was dominant in autumn–spring, coinciding with lower water temperature, higher transparency and lower nutrient and chlorophyll a (Chl a ) concentrations than in summer, when D. lumholtzii was dominant.
3. Based on the field observations, temperature optima were 24 °C for D. ambigua and 29 °C for D. lumholtzii , suggesting that temperature plays a role in determining dominance among the daphnids of subtropical Florida lakes.
4.  D. lumholtzii has not displaced native cladocerans but occupies a 'vacant' seasonal niche, unexploited due to the inability of native taxa to tolerate high temperature. Furthermore, D. lumholtzii did not significantly alter algal–zooplankton interactions. There was evidence of top–down control by grazing, but it was primarily attributable to the native taxa.     

Phenology and flight periodicity of Sirex noctilio (Hymenoptera: Siricidae) in central New York,U.S.A.

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Stream Restoration in the Upper Midwest, U.S.A.

Restoration activities intended to improve the condition of streams and rivers are widespread throughout the Upper Midwest, U.S.A. As with other regions, however, little information exists regarding types of activities and their effectiveness. We developed a database of 1,345 stream restoration projects implemented from the years 1970 to 2004 for the states of Michigan, Ohio, and Wisconsin in order to analyze regional trends in goals, presence of monitoring, spatial distribution, size, and cost of river restoration projects. We found that data on individual projects were fragmented across multiple federal, state, and county agencies, as well as nonprofit groups and consulting firms. The most common restoration goals reported for this region were in‐stream habitat improvement, bank stabilization, water‐quality management, and dam removal. The former two were most common in Michigan and Wisconsin, where salmonid fisheries enhancement appeared to be an important concern, whereas water‐quality management was most frequent in Ohio. The most common restoration activities were the use of sand traps and riprap, and other common activities were related to the improvement of fish habitat. The median cost was $12,957 for projects with cost data, and total expenditures since 1990 were estimated at $444 million. Over time, the cost of individual projects has increased, whereas the median size has decreased, suggesting that restoration resources are being spent on smaller, more localized, and more expensive projects. Only 11% of data records indicated that monitoring was performed, and more expensive projects were more likely to be monitored. Standardization of monitoring and record keeping and dissemination of findings are urgently needed to ensure that dollars are well spent and restoration effectiveness is maximized.     

Impact of the Little Fire Ant,Wasmannia auropunctata,on Native Forest Ants in Gabon1

The Neotropical little fire ant, Wasmannia auropunctata, is notorious for its negative impacts on the native biota of tropical islands, such as the Galapagos and New Caledonia, where it has been introduced. Here, I evaluate the impact of exotic W. auropunctata populations on continental Africa. I surveyed ants at nine sites in Lopé National Park in Gabon, Central Africa, and found a highly significant correlation between ant diversity and length of infestation by W. auropunctata. I found many more native ant species present in areas not infested with W. auropunctata (39.0 ± 4.6) compared with areas infested by W. auropunctata for approximately 5–10 yr (7.0 ± 6.2 and 1.7 ± 1.2, respectively). In infested areas, W. auropunctata made up the bulk of specimens collected in every plot. This study demonstrates that the threat posed by W. auropunctata to biodiversity is as serious in continental ecosystems as it is in the more fragile island ecosystems of previous studies. Introductions near waterways are particularly devastating: in Lopé, the infested territory is most extensive along waterways and occurs in a pattern that strongly suggests moving water facilitates colonization.     

Fire as a Recurrent Event in Tropical Forests of the Eastern Amazon: Effects on Forest Structure,Biomass, and Species Composition1

The effects of fire on forest structure and composition were studied in a severely fire-impacted landscape in the eastern Amazon. Extensive sampling of area forests was used to compare structure and compositional differences between burned and unburned forest stands. Burned forests were extremely heterogeneous, with substantial variation in forest structure and fire damage recorded over distances of <50 m. Unburned forest patches occurred within burned areas, but accounted for only six percent of the sample area. Canopy cover, living biomass, and living adult stem densities decreased with increasing fire inrensiry / frequency, and were as low as 10–30 percent of unburned forest values. Even light burns removed >70 percent of the sapling and vine populations. Pioneer abundance increased dramatically with burn intensity, with pioneers dominating the understory in severely damaged areas. Species richness was inversely related to burn severity, but no clear pattern of species selection was observed. Fire appears to be a cyclical event in the study region: <30 percent of the burned forest sample had been subjected to only one burn. Based on estimated solar radiation intensities, burning substantially increases fire susceptibility of forests. At least 50 percent of the total area of all burned forests is predicted to become flammable within 16 rainless days, as opposed to only 4 percent of the unburned forest. In heavily burned forest subjected to recurrent fires, 95 percent of the area is predicted to become flammable in <9 rain-free days. As a recurrent disturbance phenomenon, fire shows unparalleled potential to impoverish and alter the forests of the eastern Amazon.     

The invasion of Lantana camara L. in Forty Mile Scrub National Park,north Queensland

Abstract Seventy-three per cent of dry rainforest in Forty Mile Scrub National Park and large areas in adjacent savanna woodland have more than 5000 individuals per ha of lantana (Lantana camara L.). Transect studies in dry rainforest and savanna woodland across varying intensities of lantana infestation show a negative correlation between the density of lantana and tree cover in rainforest. The density of pig rooting is very high in areas of the dry rainforest on deep soil that was not heavily infested with lantana. It is suggested that the digging activities of these animals may cause tree death and subsequent increased light penetration, which favours lantana. The species richness of the dry rainforest declines as the density of lantana increases. However, the saplings and seedlings and the soil seed bank of dry rainforest and savanna woodland tree species have comparable densities in heavy and light lantana infestations. The proliferation of lantana results in the build up of heavy fuel loads across the boundary of dry rainforest and savanna woodland. Recent fires have killed the canopy trees in a large area of dry rainforest within the Park. Active management of Forty Mile Scrub National Park is urgent and some initiatives are suggested.     

Factors which affect the abundance of an invasive cladoceran, Daphnia lumholtzi, in U.S. reservoirs

1.  Daphnia lumholtzi is a subtropical, Old World species which is rapidly spreading throughout reservoirs in the southern U.S.A. It was first recorded in Lake Texoma (Oklahoma–Texas) in September 1991.
2. Southern U.S. reservoirs typically have strong spatial and temporal gradients in temperature, conductivity, turbidity and in the distribution of organisms. Therefore, the present experiments examined the reproductive and moulting rates, and survival of D . lumholtzi in relation to extremes of food concentration, temperature, conductivity and turbidity.
3. Increases in temperature (range = 15–29 °C) and decreases in turbidity (range = 0.6–470 NTU) increased reproductive and moulting rates, whereas food concentration only affected the rate of reproduction, while conductivity had no effects. Survival was affected only by temperature.
4.  Daphnia lumholtzi tolerates high temperatures (27–30 °C) at which other cladocerans in Lake Texoma disappear. Therefore, D . lumholtzi may exploit resources in midsummer, when there are few potential competitors.     

A Strategy for Restoration of Montane Forest in Anthropogenic Fern Thickets in the Dominican Republic

Deforested tropical areas are often colonized by competitive ferns that inhibit forest succession. In thickets of such a fern (Dicranopteris pectinata), we investigated methods for initiating restoration of tropical montane forest in the Ébano Verde Scientific Reserve (Dominican Republic). In clearings in the thickets, growth and survivorship of 18 common early‐ and late‐successional woody species were tested, with and without fertilizer (poultry litter). Three years after sowing, life history did not affect survivorship, but early‐successional species grew faster than late‐successional species (height increase 153 ± 103 cm vs. 81 ± 67 cm [mean ± 1 SD]). Inga fagifolia, a late‐successional species, and Alchornea latifolia, an early‐successional species, had 160 ± 62 cm mean height increase, and low mortality rates (<4%). In contrast, four late‐successional species (Cyrilla racemiflora, Myrcia deflexa, Prestoea acuminata var. montana, and Mora abbottii), and one early‐successional species, Ocotea leucoxylon, had approximately 39% mortality and height increase of 43 ± 48 cm. Brunellia comocladifolia had high mortality (55%), but averaged 340 ± 201 cm height increase, and was the only species whose growth was improved by fertilization. Fertilization improved survivorship of only one species, Piper aduncum. After three years, soils in the clearings had low pH and available P and did not differ significantly from soils in thickets. However, based on the growth rates and survivorship of sown woody plants, these soils did not appear to be a barrier for restoration. Although a complementary study demonstrated substantial natural regeneration, active planting should be used to increase plant density and diversity, especially where natural regeneration is poor.     

Restoration of a Forest Understory After the Removal of an Invasive Shrub, Amur Honeysuckle (Lonicera maackii)

The recruitment of native seedlings is often reduced in areas where the invasive Amur honeysuckle (Lonicera maackii) is abundant. To address this recruitment problem, we evaluated the effectiveness of L. maackii eradication methods and restoration efforts using seedlings of six native tree species planted within eradication and unmanipulated (control) plots. Two eradication methods using glyphosate herbicide were evaluated: cut and paint and stem injection with an EZ‐Ject lance. Lonicera maackii density and biomass as well as microenvironmental characteristics were measured to study their effects on seedling growth and survivorship. Mean biomass of Amur honeysuckle was 361 ± 69 kg/ha, and density was 21,380 ± 3,171 plants/ha. Both eradication treatments were effective in killing L. maackii (≥ 94%). The injection treatment was most effective on large L. maackii individuals (>1.5 cm diameter), was 43% faster to apply than cutting and painting and less fatiguing for the operator, decreased operator exposure to herbicide, and minimized impact to nontarget vegetation. Deer browse tree protectors were used on half of the seedlings, but did not affect survivorship or growth. After 3 years, survival of native seedlings was significantly less where L. maackii was left intact (32 ± 3%) compared with the eradication plots (p < 0.002). Seedling survival was significantly different between cut (51 ± 3%) and injected (45 ± 3%) plots. Species had different final percent survival and rates of mortality. Species survival differed greatly by species (in descending order): Fraxinus pennsylvanica > Quercus muehlenbergii ≥ Prunus serotina≥ Juglans nigra > Cercis canadensis > Cornus florida. Survivorship and growth of native seedlings was affected by a severe first‐year drought and by site location. One site exhibited greater spring soil moisture, pH, percent open canopy, and had greater survivorship relative to the other site (55 ± 2 vs. 30 ± 2%). Overall, both L. maackii eradication methods were successful, but restorationists should be aware of the potential for differential survivorship of native seedlings depending on species identity and microenvironmental conditions.     

Temporal dynamics of woodpecker predation on emerald ash borer (Agrilus planipennis) in the northeastern U.S.A.

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Short‐term efficacy and nontarget effects of aerial glyphosate applications for controlling Lonicera maackii (Amur honeysuckle) in oak‐hickory forests of Eastern Missouri,U.S.A.

Lonicera maackii (Amur honeysuckle) is a non‐native species that has invaded forest stands throughout the eastern United States. This research examined using aerially applied glyphosate in autumn 2013 to control L. maackii in oak‐hickory forest stands in Missouri, U.S.A. We targeted the spraying time period when L. maackii was still green and most native plants were dormant. Across treatment units, the mean difference in L. maackii stem density significantly declined (p = 0.004) by 5.4 stems per plot from spring 2013 to summer 2014 when compared to control units which increased by 1.8 stems per plot. Treated units with a high initial infestation level of L. maackii (>50% cover) had a significant (p = 0.004) decline in the mean difference in L. maackii cover of ?50.0% per plot between spring 2013 and summer 2014 compared to an average increase of 9.2% in the controls. Similar results were found for treated units with a low initial infestation level of L. maackii (10–50% cover). Mortality of native overstory and understory trees post‐treatment was negligible. In the ground layer of forest stands with a low initial L. maackii infestation level, native non‐spray‐sensitive forb cover per plot significantly increased (p = 0.023) relative to controls between summer 2013 and summer 2014 while native spray‐sensitive species cover significantly decreased (p = 0.021) during the same period. These results suggest that an aerial application of glyphosate can provide an L. maackii control option, but with trade‐offs in compositional shifts in the native ground‐layer vegetation.     

Fire regimes and forest changes in mid and upper montane forests of the southern Cascades, Lassen Volcanic National Park, California, U.S.A.

Aim Spatial and temporal variation in fire regime parameters and forest structure were assessed. Location A 2630‐ha area of mid‐ and upper montane forest in Lassen Volcanic National Park (LVNP). Methods Two hypotheses were tested concerned with fire‐vegetation relationships in southern Cascades forests: (1) fire regime parameters (return interval, season of burn, fire size, rotation period) vary by forest dominant, elevation and slope aspect; and (2) fire exclusion since 1905 has caused forest structural and compositional changes in both mid‐ and upper montane forests. The implications of the study for national park management are also discussed. Results Fire regime parameters varied by forest compositional group and elevation in LVNP. Median composite and point fire return intervals were shorter in low elevation Jeffrey pine (Pinus jeffreyi) (JP) (4–6 years, 16 years) and Jeffrey pine–white fir (Abies concolor) (JP‐WF) (5–10 years, 22 years) and longer in high elevation red fir (Abies magnifica)— western white pine (Pinus monticola) (RF‐WWP) forests (9–27 years, 70 years). Median fire return intervals were also shorter on east‐facing (6–9 years, 16.3 years) and longer on south‐ (11 years, 32.5 years) and west‐facing slopes (22–28 years, 54‐years) in all forests and in each forest composition group. Spatial patterns in fire rotation length were the same as those for fire return intervals. More growing season fires also occurred in JP (33.1%) and JP‐WF (17.5%) than in RF‐WWP (1.1%) forests. A dramatic decline in fire frequency occurred in all forests after 1905. Conclusions Changes in forest structure and composition occurred in both mid‐ and upper montane forests due to twentieth‐century fire exclusion. Forest density increased in JP and JP‐WF forests and white fir increased in JP‐WF forests and is now replacing Jeffrey pine. Forest density only increased in some RF‐WWP stands, but not others. Resource managers restoring fire to these now denser forests need to burn larger areas if fire is going to play its pre‐settlement role in montane forest dynamics.     

Effects of forest fire on headwater stream macroinvertebrate communities in eastern Washington,U.S.A.

1. Recent increases in fire frequency in North America have focused interest on potential effects on adjacent ecosystems, including streams. Headwaters could be particularly affected because of their high connectivity to riparian and downstream aquatic ecosystems through aquatic invertebrate drift and emergence. 2. Headwater streams from replicated burned and control catchments were sampled in 2 years following an intense forest fire in northeastern Washington (U.S.A.). We compared differences in benthic, drift and emergent macroinvertebrate density, biomass and community composition between five burned and five unburned catchments (14–135 ha). 3. There were significantly higher macroinvertebrate densities in burned than control sites for all sample types. Macroinvertebrate biomass was greater at burned sites only from emergence samples; in benthic and drift samples there was no significant difference between burn and control sites. 4. For all sample types, diversity was lower in the burned catchments, and the macroinvertebrate community was dominated by chironomid midges. 5. Compared to the effects of fire in less disturbed ecosystems, this study illustrated that forest fire in a managed forest may have greater effects on headwater macroinvertebrate communities, influencing prey flow to adjacent terrestrial and downstream aquatic habitats for at least the first 2 years post‐fire.