bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intra‐ and Interannual Vegetation Change: Implications for Long‐Term Research
Authors: Korb Julie E. , Fulé Peter Z. 
Published: September 2007

Abstract To draw reliable conclusions from forest restoration experiments, it is important that long‐term measurements be repeatable or year‐to‐year variability may interfere with the correct interpretation of treatment effects. We used permanent plots in a long‐term restoration study in southwestern Colorado to measure herbaceous and shrub vegetation at three dates within a single year (June, July, and August), and between years (2003 and 2005), on untreated control plots in a warm, dry mixed conifer forest. Growing season precipitation patterns were similar between 2003 and 2005, so differences in vegetation should be related primarily to differences in the sampling month. Significant indicator species for each sampling month were present within a single year (2005), primarily reflecting early‐season annuals. We found no significant differences for total species abundance (2005). Species richness, abundance, and indicator species were significantly different between years for different sampling months indicating that sampling should be conducted within a similar time frame to avoid detecting differences that are not due to treatment effects or variations in year‐to‐year climate. These findings have implications for long‐term research studies where the objectives are to detect changes over time in response to treatments, climate variation, and natural processes. Long‐term sampling should occur within a similar phenological time frame each year over a short amount of time and should be based on the following criteria: (1) the sampling period is congruent with research objectives such as detecting rare species or peak understory abundance and (2) the sampling period is feasible in regard to personnel and financial constraints.
Effects of Competition and Life History Stage on the Expression of Local Adaptation in Two Native Bunchgrasses
Authors: Rice Kevin J. , Knapp Eric E. 
Published: September 2007

Abstract Concerns about the use of genetically appropriate material in restoration often focus on questions of local adaptation. Many reciprocal transplant studies have demonstrated local adaptation in native plant species, but very few have examined how interspecific competition affects the expression of adaptive variation. Our study examined regional scales of adaptation between foothill and coastal populations of two California native bunchgrasses (Elymus glaucus and Nassella pulchra). By combining competitive manipulations with reciprocal transplants, we examined the importance of the vegetation at a site as a selective factor in the process of local adaptation. By monitoring survival and reproduction of reciprocally transplanted populations over the course of 3 years, we also studied the effect of life history stage on the expression of local adaptation. For most of the fitness components we measured, local adaptation was detected and interspecific competition consistently amplified its expression. Expression of local adaptation was especially apparent in the more inbreeding species E. glaucus and suggests that with weaker gene flow, selection may be more effective in creating ecotypes within this species. Local adaptation was detected at all life history stages but was most strongly expressed in traits associated with adult reproduction and the viability of seeds produced by the transplants. Taken together, our results indicate that the importance of local adaptation will become more apparent in the later stages of a restoration project as the plants at a site begin to reproduce and as they experience greater interspecific competition from the maturing vegetation at the site.
Post‐Flood Recovery of a Macroinvertebrate Community in a Regulated River: Resilience of an Anthropogenically Altered Ecosystem
Authors: Rader Russell B. , Voelz Neal J. , Ward James V. 
Published: September 2007

Abstract Preservation of biodiversity depends on restoring the full range of historic environmental variation to which organisms have evolved, including natural disturbances. Lotic ecosystems have been fragmented by dams causing a reduction in natural levels of environmental variation (flow and temperature) and consequently a reduction of biodiversity in downstream communities. We conducted a long‐term study of the macroinvertebrate communities before and after natural flood disturbances in an unregulated reference site (natural flows and temperatures), a regulated site (regulated flows and temperatures), and a partially regulated reference site (regulated flows and natural temperatures) on the upper Colorado River downstream from a deep‐release storage reservoir. We aimed to test the hypothesis that floods and temperature restoration would cause an increase in macroinvertebrate diversity at the regulated site. Over the short term, macroinvertebrate richness decreased at the regulated site when compared to pre‐flood levels, whereas total macroinvertebrate density remained unchanged. Over the long term (1 and 10 years after the floods), macroinvertebrate diversity and community structure at the regulated site returned to pre‐flood levels without increasing to reference conditions. Occasional floods did not restore biodiversity in this system. As long as the physical state variables remain altered beyond a threshold, the community will return to its altered regulated condition. However, temperature restoration at the partially regulated site resulted in an increase in macroinvertebrate diversity. Our results indicate that restoration of the natural temperature regime will have a stronger effect on restoring biodiversity than occasional channel‐forming floods.
Impact of Regional Species Pool on Grasshopper Restoration in Hay Meadows
Authors: Knop Eva , Schmid Bernhard , Herzog Felix 
Published: September 2007

Abstract Agri‐environment schemes are the most widely adopted political measure to maintain and restore farmland biodiversity in Europe. However, abiotic and biotic factors often limit the success of ecological restoration. Among the biotic factors, the size of the local and regional species pool is a major constraint. This is only well documented for plants. We therefore wanted to know if a small regional species pool can also limit restoration efforts of invertebrates. Specifically, we tested if by relocating grasshoppers from further away, we could overcome regional species pool limitations on hay meadows under the Swiss agri‐environment scheme, so‐called Ecological Compensation Area meadows (ECA meadows). All meadows had been under restoration for 6 years and were formerly intensively used hay meadows. Two grasshopper species, Euthystira brachyptera and Mecostethus parapleurus, were selected; E. brachyptera was not found in the regional species pool and M. parapleurus had nearly disappeared. In 2004, 1,400 grasshopper individuals of each species were taken from the nearest large source populations and distributed equally on seven ECA meadows and seven control meadows. In 2005, we evaluated whether the species had successfully established. Only one individual of M. parapleurus was found. We conclude that a small regional species pool is not the only constraint for the reestablishment of grasshoppers on restoration meadows. Also, other factors such as habitat quality appear to constrain the reestablishment of grasshoppers on restoration meadows. Additional restoration efforts specifically targeted at grasshopper restoration are needed, and innovative techniques have to be developed to overcome the relocation constraints.
The Effect of Fire Reintroduction on Endemic and Rare Plants of a Southeastern Glade Ecosystem
Authors: Scot Duncan R. , Anderson Corinna B. , Sellers Heather N. , Robbins Erin E. 
Published: September 2007

AbstractOpen habitats dominated by herbaceous plants on thin, rocky soils occur within the forests of eastern North America. Although these habitats vary in origin, structure, geology, and species composition, all contribute greatly to regional biodiversity by harboring endemic and/or rare plants. Little is known about how disturbances affect plant populations in these ecosystems. Fire once was a frequent natural disturbance in the Ketona dolomite glades of Alabama, an ecosystem harboring eight endemic taxa and numerous other species of conservation concern. We designed an experiment to determine how the reintroduction of fire into the glades and surrounding longleaf pine forests affects populations of rare glade plant species. Experimental and control plots were established within the glades. Experimental plots were burned in April 2004, and all plots were surveyed during two subsequent growing seasons (2004 and 2005). Populations of three of 14 species of conservation concern declined significantly after the initial fire but recovered the next year. Among other herbaceous species, only five and two differed in population size in 2004 and 2005, respectively. In 2004, more species were more abundant in control than burned plots, but this difference was not detected in 2005. Multivariate community‐level analyses of species presence–absence suggested that the effects of fire were negligible by the 2005 survey. Populations of young trees that had invaded the glades declined dramatically as a result of treatment fires. These results suggest that the reintroduction of fire will not harm glade species and may help prevent encroachment of the surrounding forest.
Has Botanical Enhancement of Broad‐Leaved Plantations in Milton Keynes, United Kingdom, Resulted in More Woodland‐Like Insect Assemblages?
Authors: Moffatt Colin , Morton Alan J. , McNeill Stuart 
Published: September 2007

Abstract Two methods of invertebrate sampling were used to determine how the deliberate introduction of field layer vegetation to broad‐leaved plantations influenced the associated insect assemblages. Enclosed pitfall traps and tent‐like emergence traps were employed at (1) 25‐year‐old plantations where botanical enhancement had taken place a decade previously; (2) “nonenhanced” plantations of a similar age; and (3) local ancient woods, all in Milton Keynes, Buckinghamshire, United Kingdom. The aim was to discover whether enhancement had produced a community intermediate to nonenhanced plantations and naturally established woodland. Enhancement had not successfully created plantations botanically more woodland‐like and plantation types were not constant; however, plant species richness had increased. This was also true of the insect assemblages (Coleoptera, Diptera and Hemiptera), which showed more variation in composition, though woodland communities could still be distinguished. However, those insect species present in the naturally established woods did have a significantly greater frequency and abundance in the enhanced plantations compared to the nonenhanced plantations, especially so with “woodland edge” species. Mantel tests showed significant correlations between the plant species present and insect assemblages taken by both sampling types. Although insect species richness was not significantly higher in the enhanced plantations, this correlated strongly with plant species richness and a measure of vegetation volume. The overall findings suggest that the enhancement had created plantations only subtly more like the local woodlands, though the insect assemblages had responded. However, relative to the time scale of woodland development, it is still early days.
Local Adaptation and Effects of Grazing among Seedlings of Two Native California Bunchgrass Species: Implications for Restoration
Authors: Hufford Kristina M. , Mazer Susan J. , Camara Mark D. 
Published: September 2007

Abstract Adaptation to environmental factors may influence the germination and establishment of focal species in ecological restoration. Reciprocal transplants remain one of the best methods to detect local adaptation, but long‐term studies are often not feasible. We conducted reciprocal transplants of the native California bunchgrasses Elymus glaucus and Bromus carinatus between two central California locations to seek evidence of adaptation to local environmental conditions in a single growing season. Experimental plots at one location included grazed and ungrazed sites. The combination of locations and grazing treatments allowed us to determine whether the ability to detect evidence for adaptation depended on grazing regime. In addition, we measured the direct effects of grazing on seedling growth and survival concurrent with our investigation of local adaptation. We detected a homesite advantage for seedling growth or survival in both species, but the factors contributing to adaptive differentiation were species specific. Evidence of local adaptation was detected for seedling biomass in Bromus and for survivorship in Elymus. The homesite advantage observed in both species was greatly reduced under grazed conditions and in Elymus was significant only in the ungrazed plots. Climate and soil analyses detected significant differences between locations in five soil attributes and two climate variables. In particular, differences in exchangeable magnesium indicated that one of the two transplant locations consisted of serpentine soil, which is widely known to drive adaptation in plant populations. Together, these results suggest that it is possible to investigate the scale and factors involved in local adaptation with short‐term transplant studies.
Soil Nitrogen Conditions Approach Preinvasion Levels following Restoration of Nitrogen‐Fixing Black Locust (Robinia pseudoacacia) Stands in a Pine–Oak Ecosystem
Authors: Malcolm Glenna M. , Bush Douglas S. , Rice Steven K. 
Published: September 2007

AbstractRestoring native plant communities on sites formerly occupied by invasive nitrogen‐fixing species poses unique problems due to elevated soil nitrogen availability. Mitigation practices that reduce available nitrogen may ameliorate this problem. We evaluated the effects of tree removal followed by soil preparation or mulching on native plant growth and soil nitrogen transformations in a pine–oak system formerly occupied by exotic nitrogen‐fixing Black locust (Robinia pseudoacacia) trees. Greenhouse growth experiments with native grasses,Andropogon gerardiiandSorghastrum nutans, showed elevated relative growth rates in soils from Black locust compared with pine–oak stands. Field soil nutrient concentrations and rates of net nitrification and total net N‐mineralization were compared 2 and 4 years since Black locust removal and in control sites. Although soil nitrogen concentrations and total net N‐mineralization rates in the restored sites were reduced to levels that were similar to paired pine–oak stands after only 2 years, net nitrification rates remained 3–34 times higher in the restored sites. Other nutrient ion concentrations (Ca, Mg) and organic matter content were reduced, whereas phosphorus levels remained elevated in restored sites. Thus, 2–4 years following Black locust tree removal and soil horizon mixing achieved through site preparation, the concentrations of many soil nutrients returned to preinvasion levels. However, net nitrification rates remained elevated; cover cropping or carbon addition during restoration of sites invaded by nitrogen fixers could increase nitrogen immobilization and/or reduce nitrate availability, making sites more amenable to native plant establishment.
Organic Matter Stimulates Bacteria and Arbuscular Mycorrhizal Fungi in Bauhinia purpurea and Leucaena diversifolia Plantations on Eroded Slopes in Nepal
Authors: Shrestha Vaidya Geeta , Shrestha Keshab , Khadge Buddi R. , Johnson Nancy C. , Wallander Håkan 
Published: September 2007

Abstract Erosion resulting from landslides is a serious problem in mountainous countries such as Nepal. To restore such sites it is essential to establish plant cover that protects the soil and reduces surface erosion. Mycorrhizal fungi growing in symbiosis with plants are essential in this respect because they improve both plant nutrient uptake and soil structure. We investigated the influence of organic matter and P amendment on recently produced biomass of bacteria and arbuscular mycorrhizal (AM) fungi in eroded slopes in Nepal. Eroded soil mixed with different types of organic matter or P was placed in mesh bags, which were buried around trees of Bauhinia purpurea and Leucaena diversifolia between June 2003 and December 2003 (the wet season) or between December 2003 and June 2004 (the dry season). Signature fatty acids were used to determine bacterial and AM fungal biomass after the 6‐month intervals. The amount and composition of AM fungal spores were analyzed in the mesh bags from the dry season. More microbial biomass was produced during the wet season than during the dry season. Furthermore, organic matter addition enhanced the production of AM fungal and bacterial biomass during both periods. The positive influence of organic matter addition on AM fungi could be an important contribution to plant survival in plantations on eroded slopes. Different AM spore communities and bacterial profiles were obtained with different organic amendments and this suggests a possible way of selecting for specific microbial communities in the management of eroded sites.
The Role of Endangered Species Reintroduction in Ecosystem Restoration: Tortoise–Cactus Interactions on Española Island, Galápagos
Authors: Gibbs James P. , Marquez Cruz , Sterling Eleanor J. 
Published: September 2007

Abstract We evaluated the role that endangered species reintroduction efforts can play in the larger context of ecosystem restoration. To do so, we examined interactions between endangered giant tortoises (Geochelone nigra hoodensis), currently being reintroduced to Isla Española, Galápagos, and an arboreal cactus (Opuntia megasperma var. megasperma), which is itself endangered and a keystone resource for many animals on the island. We collected information on spatial patterns of occurrence of cacti, tortoises, and woody vegetation and compared recruitment of juvenile cacti in areas occupied versus unoccupied by tortoises. Reintroduced tortoises appeared to suppress cactus recruitment near the few remaining adult cacti at the study site, but facilitate it at longer distances, with tortoise–cactus interactions mediated by the presence of woody vegetation, which likely alters tortoise movements and thereby patterns of cactus seed dispersal. The net effect of tortoises on cacti appeared to be positive insofar as tortoise presence was associated with greater recruitment of juveniles into cactus populations. Our study provides support for reintroducing endangered reptiles and other animals to aid ecosystem restoration in areas where they might once have played an important role in grazing upon and dispersing plants.
First‐Generation Forests Are Not Necessarily Worse than Long‐Term Managed Forests for Lichens and Bryophytes
Authors: Lõhmus Asko , Lõhmus Piret 
Published: September 2007

AbstractFor biodiversity, natural afforestation is generally more favorable than plantation‐based afforestation, but the difference may be less important if both methods fail to provide habitats for sensitive old‐forest species. Given that some conditions, such as substrates, can be actively restored in new forests, their effect on biodiversity should be separated from dispersal limitation. We asked whether, and to what extent, lichen and bryophyte vegetation is impoverished on old‐forest substrates in non‐intensively afforested lands of the twentieth century compared with similar substrates in managed long‐term forestlands. We measured the diversity and abundance of all lichens and bryophytes as well as the cover of human‐sensitive (hemerophobic) species on large deciduous trees, logs, snags, and windthrows on 30 random 2‐km transects in a 900‐km2forest landscape in Estonia, hemiboreal Europe. Altogether, 235 species, including 39 hemerophobic species, were detected on 781 structural elements. New forests were not significantly worse than long‐term forests in any of the cryptogam community characteristics, which was explained by the predominance of natural afforestation (many native tree species present), time for substrate development and cryptogam dispersal (most stands >40 years old), few cuttings in the new forests (only about 20% of stands thinned), and short distances to long‐term forests (67% of substrates within 250 m). Under such conditions, afforested areas appeared to be as suitable as traditional managed forests both for developing multifunctional forestry and as starting points for habitat restoration for threatened species.
Decreasing the Abundance of Juncus effusus on Former Agricultural Lands with Noncalcareous Sandy Soils: Possible Effects of Liming and Soil Removal
Authors: Smolders Alfons J. P. , Lucassen Esther C. H. E. T. , Van Der Aalst Martijn , Lamers Leon P. M. , Roelofs Jan G. M. 
Published: September 2007

Abstract More and more agricultural land in the Netherlands is becoming available for ecological restoration projects. However, nutrient levels in the top layer of the soils are high because the agricultural lands have been heavily fertilized for decades. As drainage ditches are no longer maintained when agricultural use ends, the agricultural lands usually become much wetter. As a result, former agricultural soils tend to develop extensive monotonous stands of Juncus effusus, which have little value from an ecological point of view. In this article, we present the results of field measurements/observations and experiments to examine the relationship between nutrient availability and J. effusus growth. In addition, we present and discuss results of experiments to study the potential beneficial effects of liming. Our findings show that the growth of J. effusus on moist or wet soils seems to be strongly determined by the Olsen‐P concentration in the soil. The restoration of diverse, species‐rich vegetation types on former agricultural lands with a noncalcareous sandy soil will in most cases not be possible within a reasonable time span without topsoil removal. Liming might be a valuable additional measure to enhance the quality of the soil after topsoil removal, and to prevent mobilization of P to groundwater or surface water. If removal of the topsoil is considered to create P limitation, it is important to study P concentrations at various depths to establish the amount of soil that has to be removed.
Declining Diversity in Natural and Restored Salt Marshes: A 30‐Year Study of Tijuana Estuary
Authors: Zedler Joy B. , West Janelle M. 
Published: September 2007

AbstractBetween 1974 and 2004, Tijuana Estuary’s natural salt marsh underwent pulse disturbance (an 8‐month nontidal period in 1984), which caused the sudden loss of two short‐lived halophytes (Salicornia bigelovii[Sb] andSuaeda esteroa[Se]) and rapid dominance of a productive native succulent (Sa. virginica[Sv]), plus ramp disturbance that led to gradual codominance byJaumea carnosa(Jc) (another productive succulent) by 1994. Species richness was high in 1974 (4.2 species/0.25‐m2plot), low in 1984 (1.4 species), and not fully recovered by 1994 (3.7 species) or 2004 (3.9 species). Restoration efforts (reseeding former habitat and excavating and planting new sites) did not recover the populations of Sb or Se. In a 1997 project, plantings of these and six other native halophytes survived initially, but by 2005, short‐lived species were lost and Sv and Jc dominated, as in the natural marsh. In a 2000 restoration site, planting mortality was high for five species, but Sv recruited voluntarily and dominated by 2005. We attribute recent vegetation changes to frequent catastrophic storms, flooding, and sedimentation, which contrasted strongly with the benign conditions of decades prior to 1974. Sediment blocked tidal channels in 1984 and gradually elevated the marsh plain, degrading the diverse salt marsh and hindering efforts to restore it. Future restoration efforts will require even greater control over sediment inflows plus contouring sites to include natural topographic features that appear critical to sustaining high species richness and evenness.