bluuebunny/crossref_metadata_2025_split huggingface dataset:
Problems, Approaches, and Results in Restoration of Dutch Calcareous Grassland During the Last 30 Years
Authors: Willems J. H. 
Published: March 2003

AbstractThis paper is based on research of the restoration of species‐rich calcareous grasslands in The Netherlands, over the last 30 years. Chalk grassland is a semi‐natural vegetation with a high density of species at a small scale. This type of vegetation was once widespread in Western Europe as common grazing land, mainly for flocks of sheep for which the main function was dung production. In some regions of Central Europe, these grasslands were also used for hay production. The dung was used to maintain arable field production at a reasonable level. In the chalk district in the southernmost part of The Netherlands some 25 sites of this vegetation, varying in area from 0.05–4.5 ha, are still present. Chalk grassland completely lost its significance for modern agricultural production after the wide application of artificial fertilizer following World War II. This grassland has a high conservation value both for plants and animal species, of which a large number of species are exclusively restricted to this biotope. When conservation activities started at a large scale in the early 1960s, three different types of restoration activities could be distinguished: (1) restoration of fertilized sites; (2) restoration of abandoned grasslands; and (3) recreation of chalk grassland on former arable fields. The main aim of the restoration attempt is to create and/or improve sustainable conditions for both plant and animal species characteristic of the chalk grassland ecosystem. In the process of restoration, several phases of different activities can be distinguished: (1) pre‐restoration phase, during which information of the land use history is collected and, based on these data, clear restoration goals are established; (2) initial restoration phase, during which effects of former, non‐conservational land use has to be undone in order to stimulate germination and establishment of target species originating from soil seed bank and species pool; (3) consolidation phase, including the introduction and continuation of a regular management system for sustainable conservation; and (4) long‐term conservation strategy, including measures to prevent disturbance from the outside and genetic erosion and extinction of locally endangered plant populations.
Restoration of Fragmented Landscapes for the Conservation of Birds: A General Framework and Specific Recommendations for Urbanizing Landscapes
Authors: Marzluff John M. , Ewing Kern 
Published: March 2003

AbstractHumans fragment landscapes to the detriment of wildlife. We review why fragmentation is detrimental to wildlife (especially birds), review the effects of urbanization on birds inhabiting nearby native habitats, suggest how restoration ecologists can minimize these effects, and discuss future research needs. We emphasize the importance of individual fitness to determining community composition. This means that reproduction, survivorship, and dispersal (not simply community composition) must be maintained, restored, and monitored. We suggest that the severity of the effects of fragmentation are determined by (1) the natural disturbance regime, (2) the similarity of the anthropogenic matrix to the natural matrix, and (3) the persistence of the anthropogenic change. As a result, urbanization is likely to produce greater effects of fragmentation than either agriculture or timber harvest. Restoration ecologists, land managers, and urban planners can help maintain native birds in fragmented landscapes by a combination of short‐ and long‐term actions designed to restore ecological function (not just shape and structure) to fragments, including: (1) maintaining native vegetation, deadwood, and other nesting structures in the fragment, (2) managing the landscape surrounding the fragment (matrix), not just the fragment, (3) making the matrix more like the native habitat fragments, (4) increasing the foliage height diversity within fragments, (5) designing buffers that reduce penetration of undesirable agents from the matrix, (6) recognizing that human activity is not compatible with interior conditions, (7) actively managing mammal populations in fragments, (8) discouraging open lawn on public and private property, (9) providing statutory recognition of the value of complexes of small wetlands, (10) integrating urban parks into the native habitat system, (11) anticipating urbanization and seeking creative ways to increase native habitat and manage it collectively, (12) reducing the growing effects of urbanization on once remote natural areas, (13) realizing that fragments may be best suited to conserve only a few species, (14) developing monitoring programs that measure fitness, and (15) developing a new educational paradigm.
Secondary Succession and Natural Habitat Restoration in Abandoned Rice Fields of Central Korea
Authors: Lee Chang‐Seok , You Young‐Han , Robinson George R. 
Published: March 2003

AbstractFloristic composition and soil characteristics (moisture, pH, nutrient contents) in abandoned upland rice paddies of different ages were analyzed to clarify the regenerative aspects of succession as a tool for habitat restoration. The study sites represented five seral stages: newly abandoned paddy fields; successional paddy fields abandoned for 3, 7, and 10 years; and a 50‐year‐old Alnus japonica forest. A vegetation sere was apparent in changes of dominant plant species in the order Alopecurus aequalis var. amurensis (annual grass), Aneilema keisak (annual forb), Juncus effusus var. decipiens (rush), Salix koriyanagi (willow), and Alnus japonica (alder) communities. These temporal stages resemble the spatial zonation of vegetation in local riparian floodplain ecosystems, indicating a hydrosere, with soil moisture decreasing over time. Age distributions and life forms of the dominant plant species support a “tolerance” model of secondary succession, in which the established species persist into later successional stages. Persistence of earlier colonizers led to a net cumulative increase in species richness and a more even distribution of species cover with increasing field age. Between 10 and 50 years, vegetation stabilizes as an alder community. Soil moisture content decreased steadily with paddy field age after an initial rise immediately after their abandonment, whereas pools of organic matter, N, P, K, Ca, and Mg, increased with field age. The pace and direction of recovery of native vegetation and natural soil properties in these abandoned rice paddies resembled classic old field succession, a form of secondary succession that often serves as a template for guiding restoration efforts. Active intervention, in particular dismantling artificial levees, could accelerate the recovery process, but natural habitat recovery generally appears sufficiently robust to achieve “passive” restoration of this rare community without intervention.
Use of Shallow Basins to Restore Cutover Peatlands: Hydrology
Authors: Price Jonathan S. , Rochefort Line , Campeau Suzanne 
Published: March 2003

AbstractBasins 20‐, 10‐, and 4‐m wide were excavated 15 to 20 cm into cutover peat fields near Lac Saint Jean, Québec, Canada to facilitate the establishment of Sphagnum mosses. Sphagnum diaspores (fragments) and straw mulch were spread over the excavated surfaces, a control peat field, and a mulch‐protected site without basins. Mean water tables in the 20‐, 10‐, and 4‐m wide basins and the mulch‐protected site were 27.2, 8.3, 11.4, and 9.7 cm higher, respectively, than in the control peat field in May to August 1996. Similar improvements were observed in 1997 (a drier summer). The higher water table was due to lowering of the peat surface with respect to the local water table, retention of meltwater and stormwater by the peripheral ridges formed during excavation, retention of water during drier periods by the groundwater mound beneath the ridges, and mulch. Soil moisture was always higher in the experimental basins than in the control peat field or in the mulch‐protected site, demonstrating the superior soil wetness characteristic of sites with basins and straw mulch. Water tension data signaled the absence of the capillary fringe (i.e., capillary drainage) near the surface for some finite period, thus possibly limiting water for best Sphagnum growth. At the experimental basins and mulch‐protected site, 100% of these periods lasted four or fewer days. In the control peat field, 20% of the periods when capillary drainage had occurred lasted more than four days, with one period of 17 days. The mulch protection alone provided considerable improvement in hydrological conditions compared with the control peat field, but the additional water retained in the experimental basins protected against Sphagnum desiccation and loss during more extreme dry periods.
Improvement Of Peripheral Nerve Structure By 15‐Month Aldose Reductase Inhibition With Fidarestat In Stz‐Induced Diabetic Rats
Authors: Kato N , Mizuno K , Makino M , Suzuki T , Yagihashi S. 
Published: March 2003

There has been no report documenting the effects of long‐term aldose reductase (AR) inhibition one year or more on peripheral neuropathy of streptozotocin‐induced diabetic rats (STZ‐rats). Fidarestat (SNK‐860) is a potent AR inhibitor that possesses the beneficial effects on the nerve dysfunction in early stage of diabetic rats (1). In the present study, we investigated the effects of 15 months of treatment with fidarestat on functional, morphological and metabolic abnormalities in the peripheral nerve of STZ‐rats. Fidarestat treatment inhibited the slowing of F‐wave conduction velocity and motor nerve conduction velocity by about 70% and normalized the slowing of sensory nerve conduction velocity. Morphometric analysis of myelinated fibers demonstrated that the frequencies of abnormal fibers such as paranodal demyelination, Wallerian degeneration and axonal sequestration were reduced to the extent of normal levels by fidarestat. Axonal atrophy, reduction of myelin sheath thickness and ratio of large fibers were also inhibited. The effects of fidarestat on functional and morphological changes were accompanied by correction of the increased sorbitol, fructose and decreased myo‐inositol in nerve. It was thus demonstrated that long‐term inhibition of increased polyol pathway flux by fidarestat was beneficial for the development of functional and structural neuropathy in STZ‐rats.(1) Mizuno, K., et al. (1999). J. Diab. Comp., 13,141‐150.
APPARENT LIGHT REQUIREMENT FOR ACTIVATION OF PHOTOSYNTHESIS UPON REHYDRATION OF DESICCATED BEACHROCK MICROBIAL MATS1
Authors: Schreiber Ulrich , Gademann Rolf , Bird Paul , Ralph Peter J. , Larkum Anthony W. D. , Kühl Michael 
Published: March 2003

Photosynthetic electron transport of beachrock microbial mats growing in the intertidal zone of Heron Island (Great Barrier Reef, Australia) was investigated with a pulse amplitude modulation chl fluorometer providing four different excitation wavelengths for preferential excitation of the major algal groups (cyanobacteria, green algae, diatoms/dinoflagellates). A new type of fiberoptic emitter‐detector unit (PHYTO‐EDF) was used to measure chl fluorescence at the sample surface. Fluorescence signals mainly originated from cyanobacteria, which could be almost selectively assessed by 640‐nm excitation. Even after desiccation for long time periods under full sunlight, beachrock showed rapid recovery of photosynthesis after rehydration in the light (t1/2∼ 15 min). However, when rehydrated in the dark, the quantum yield of energy conversion of PSII remained zero over extended periods of time. Parallel measurements of O2concentration with an oxygen microoptode revealed zero oxygen concentration in the surface layer of rehydrated beachrock in the dark. Upon illumination, O2concentration increased in parallel with PSII quantum yield and decreased again to zero in the dark. It is proposed that oxygen is required for preventing complete dark reduction of the PSII acceptor pools via the NADPH‐dehydrogenase/chlororespiration pathway. This hypothesis is supported by the observation that PSII quantum yield could be partially induced in the dark by flushing with molecular oxygen.Abbreviations:EDF, emitter‐detector unit; Fo, fluor‐escence yield of dark‐adapted sample; Fm, maximal fluorescence yield measured during saturation pulse; Fv, variable fluorescence yield; LED, light‐emitting diode; PAM, pulse amplitude modulation; PQ, plastoquinone
Mycosporine‐Like Amino Acid Intercalibration Effort Using Replicate Samples
Authors: Zimba P. V. , Boue S. 
Published: March 2003

AbstractThe measurement of mycosporine‐like amino acids (MAAs) has several inherent problems, including the lack of commercial standards for identification and quantification. This symposium provided the opportunity to coordinate analyses with six laboratories actively involved in MAA research. Two samples were provided to each laboratory and included freeze‐dried nori (Porphyra sp.) and a freeze‐dried (filtered) sample of the cyanobacteria Microcystis aeruginosa Kützing. Each laboratory provided extraction methodologies, chromatograms of the identified peaks, as well as estimates of the concentration of each analyte. All laboratories were able to identify major chromatographic components of the samples (Porphyra: shinorine, porphyra, mycosporine 2‐glycine, asterina, palythine; Microcystis: shinorine, porphyra). Sequential cold (4 °C for 18 h) and hot (45 °C for 2 h) extractions of the same sample resulted in differing analyte recovery. Several currently unidentified compounds were observed in freshwater samples.
Origin and Early Evolution of Plant Body Symmetry and Gravity Responses
Authors: Cook M. E. , Graham L. E. 
Published: March 2003

AbstractLand plant bodies exhibit both apical–basal and radial symmetry, and they are able to detect and respond to gravitational forces. These attributes were, likely important factors in the success of earliest plants on land. This study focuses on features of charophycean green algae likely to have been pre‐adaptive to early establishment of plant symmetry and gravitational responses, though most modern charophyceans occupy aquatic habitats where the buoyancy of water counteracts the effects of gravity. Trait mapping suggests that even the earliest‐divergent modern members of the streptophyte clade have bodies whose symmetry departs significantly from the spherical condition, and that cellular mechanisms defining aspects of radial symmetry and polarized tip growth originated early. Genes, cell biological approaches, and taxa are identified for which further exploration is likely to illuminate early evolution of plant body symmetry and gravity responses.
Post‐European Sedimentation and Nutrient Loading in Lake St. Croix: A Natural Impoundment on the St. Croix River, USA
Authors: Edlund M. B. , Triplett L. , Engstrom D. R. 
Published: March 2003

AbstractThe final 37 km of the St. Croix River were naturally dammed by the Mississippi River to form Lake St. Croix approximately 9500 years ago. The St. Croix River is currently regarded as having ‘exceptional resource value’, as one of the least impacted large Midwest river systems. Twenty‐four 2‐m piston cores were recovered in 1999–2001 from Lake St. Croix sub‐basins to identify post‐European settlement signals of land use, trophic change, and sedimentation using a whole‐basin approach to reconstruct loading history of nutrients, sediments, heavy metals, and organics. Dating chronologies based on 210Pb inventories indicated both cores recovered a sediment sequence dating from pre‐ and post‐European settlement (c. 1850) in the St. Croix River basin. Select cores were subjected to magnetic susceptibility, loss‐on‐ignition, and diatom microfossil analysis. Sedimentary increases in magnetic susceptibility were indicative of increased erosion and transport of ferromagnetic mineral grains due to initiation of settlement, logging, and agricultural activities in the basin. A three‐fold increase in sediment accumulation began in the mid‐1800s in the northern basin and by 1900 in the southern basin. Diatom accumulation increased 20–50‐fold since settlement with a shift from benthic‐ to planktonic‐dominated assemblages. Simultaneous with the assemblage shift were the introduction and establishment of many planktonic diatoms considered ubiquitous indicators of eutrophy. The fossil diatom assemblages were further analyzed using weighted‐averaging calibration and reconstruction of historical water column total phosphorus (TP). Reconstructed TP values showed that water column nutrient values have increased 2.5–3‐fold since presettlement times. Presettlement values of about 0.02 mg/L TP were found in both cores with TP increases beginning c. 1910 and especially dramatic increases after World War II. Modern reconstructed TP values (about 0.055 mg/L) were similar to TP concentrations reported from monitoring during the last few decades; however, the river was clearly impacted well before monitoring efforts were begun.
Differences Among Coccoid Green Algal Communities in Minnesota and North Dakota Lakes
Authors: Fawley P. K. , Fawley M. W. 
Published: March 2003

AbstractVery little is known about the diversity and distribution of freshwater unicellular coccoid green algae. The simple morphology and small size of these organisms make reliable identification extremely difficult. Current hypotheses suggest that species of coccoid algae are widely distributed, opportunistic organisms that are always present in aquatic systems. These hypotheses are based on the assumption that phytoplankton communities include only one or a few species of coccoid algae. We examined the diversity and distribution of green‐colored autosporic coccoid algae in Itasca State Park in Minnesota and Arrowwood National Wildlife Refuge in North Dakota using molecular techniques and light microscopy. Our preliminary results indicate a higher level of diversity of coccoid green algae than has been reported in regional flora. Contrary to current hypotheses, communities of coccoid green algae vary among the different lakes.
Species Diversity of Microbial Communities in a Northern Temperate Humic Lake
Authors: Graham J. M. , Kent A. D. , Lauster G. H. , Yannarell A. C. , Graham L. E. , Kratz T. K. , Triplett E. W. 
Published: March 2003

AbstractSpecies richness and species diversity of bacterioplankton, phytoplankton and protoplankton were examined in Crystal Bog, a humic lake in northern Wisconsin, as part of an NSF sponsored Microbial Observatory Program. Crystal Bog is part of the North Temperate Lakes Long‐Term Ecological Research site. Automated ribosomal intergenic spacer analysis (ARISA) was used to assess bacterial diversity. Phytoplankton and protoplankton were enumerated in a settling chamber with an inverted microscope. Four distinct phases in the ice‐free season of the bog can be recognized based on microbial populations. The first phase extends from ice‐out until about the first week of April. During this phase three species of dinoflagellates come to dominate the phytoplankton, with Glenodinium quadridens representing 60% of total phytoplankton biovolume. By mid‐April the spring dinoflagellate blooms collapse. The second phase is a period of instability as a series of species dominates the phytoplankton. In mid‐July dinoflagellates again dominate the third phase, and Peridinium limbatum alone represents 90% of the bog phytoplankton. The fourth phase is a stable period as P. limbatum slowly declines in late summer and fall. A strong correlation was found between bacterial and phytoplankton diversity (Shannon–Weaver Index) in this bog, suggesting the two microbial communities are linked. The protoplankton, however, were relatively uniform throughout the ice‐free period. The ice‐covered period may be treated as a fifth phase. When snow accumulates over the ice‐covered bog, light penetration is blocked and photosynthesis shut off. Heterotrophic protozoa assume dominance in the plankton.
The Plastid of Dinophysis (Dinophyceae): Phylogenetic Evidence for a Permanent Replacement
Authors: Hackett J. D. , Maranda L. , Bhattacharya D. 
Published: March 2003

AbstractIn the photosynthetic dinoflagellate Dinophysis, pigment composition and ultrastructural characters place the origin of the chloroplast with the cryptophytes. Presented here is the first molecular data from the plastid of Dinophysis. We cloned and sequenced the coding regions of psbA and small subunit (SSU) rDNA from four populations of D. acuminata and from D. acuta. These data were used to test two hypotheses about Dinophysis plastid evolution: (1) The plastid is of cryptophyte origin; and (2) The plastid is a permanent replacement. The psbA‐coding region was identical among the populations of D. acuminata and between this species and D. acuta. On the other hand, the SSU rDNA showed polymorphisms, both between species and among populations. Phylogenetic analysis shows that both psbA and SSU rDNA sequences firmly place the Dinophysis spp. plastid within the cryptophytes, confirming its origin through plastid replacement. The polymorphic SSU rDNA sequences group together and are sister to a cryptophyte ultraplankter (OCS20). The SSU rDNA sequence heterogeneity between species (about 1%) is comparable to the heterogeneity among different isolates of D. acuminata, suggesting these are population‐level differences and not indicative of different plastid captures by Dinophysis. Interestingly, a second class of cloned coding regions was also isolated from each population. These psbA and SSU rDNA sequences were evolutionarily more divergent and specifically related to florideophyte red algae. Given the mixotrophic habit of Dinophysis, the possibility arises that this second class may have come from red algal preys in the food vacuoles of our single‐cell isolates. These results highlight the importance of sampling multiple genes and populations in determining the complex evolutionary history of the Dinophysis plastid.
A New Method for Studying Nutrient Limitation of Periphyton: A Case Study From Acid Mine Drainage Streams
Authors: Hamsher S. E. , Casamatta D. A. , Filkin N. R. , McClintic A. S. , Chiasson W. B. , Verb G. R. , Vis M. L. 
Published: March 2003

AbstractAcid mine drainage (AMD) affects about 16 900 km of streams in the Appalachian region, but little is known about the biology of these habitats. Typically, these habitats have low primary productivity most likely due to metal stress. However, these streams are also very low in nutrients. Traditionally, nutrient limitation studies of periphyton have been conducted employing terracotta pots. Recently, research has concluded that this methodology may have inherent flaws due to variable porosity. Therefore, development of new nutrient diffusing substrates is needed. To test a new approach for nutrient diffusion, Petri dishes were filled with agar and the nutrient of choice. A Whatman glass microfiber filter (GF/F) was attached to the top of the dish, which served as the medium through which the nutrients diffused and as a uniform surface area for periphyton colonization. Before testing in a stream impacted by acid mine drainage, laboratory studies were conducted to simulate field conditions. The Petri dishes readily diffused the nutrients and were durable to the acid conditions. Six replicates with a control, nitrogen (0.5 M), phosphorus (0.5 M), and nitrogen + phosphorus (0.5 M of each) Petri dishes were deployed in four AMD impacted streams for the month of February. Samples were analyzed for chlorophyll a, ash‐free dry mass (AFDM), and taxa present. The chlorophyll a analyses showed the phosphorus treatment to be significantly (P < 0.05) greater than all other treatments and the nitrogen treatment was significantly (P < 0.05) lower. However, these trends were not seen in the AFDM results with no difference among treatments detected. Seasonal assessment of this approach is currently under way.