Long-lasting effects on nitrogen cycling 12 years after treatments cease despite minimal long-term nitrogen retention

Atmospheric deposition of biologically active nitrogen (N) has increased dramatically over the past 60 years, with far-reaching impacts on the structure and function of many ecosystems. Much research has examined the initial impacts of N enrichment; however, few studies have been multidecadal, and even fewer long-term studies have examined the longevity of N-induced impacts on N cycling after inputs cease. Here, we address this gap by reporting the state of key N pools and fluxes in a Minnesota grassland for plots that received N addition for 10 years and then none for 12 years, in comparison with plots that received annual N treatment for the entire 22 years. We found weak evidence for long-term N retention in plots that ceased receiving treatment; and in plots that continued to receive N over the 22-year period, retention that was high after 12 years (50–100% of inputs) was greatly reduced after 22 years (to 15%). In spite of this, net N mineralization rates remained elevated in plots that ceased receiving treatment 12 years prior, likely because N-rich litter maintained higher N-cycling rates. These results suggest (1) some systems do not retain much deposited N, with potentially large impacts on downstream habitats; (2) the previously reported high retention efficiencies for this and many other terrestrial ecosystems may be relatively short-lived as N sinks become saturated over time; and (3) the effects of even small amounts of retained N in N-limited environments may be particularly long-lasting. In total, these findings highlight the importance of long-term studies in evaluating the impacts of chronic N deposition to ecosystems, and urge additional research examining dynamics following N cessation to evaluate the reversibility of these impacts.     

Life history,damage assessment and control of Trioza hopeae (Hemiptera: Psylloidea), a serious pest on Hopea odorata (Malvales: Dipterocarpaceae) in Vietnam

Young plants of the commercially important timber species Hopea odorata Roxb. are seriously damaged by the psyllid Trioza hopeae Burckhardt & Vu in nurseries in South Central and Southern Vietnam. Farmers routinely use Class 1 toxic insecticides to control the psyllids but these pose serious health risks in the urban environment. As a precursor to developing a pest management strategy, we studied the life cycle of T. hopeae and trialed several control measures. Trioza hopeae is polyvoltine with overlapping generations peaking in mid wet season. Females laid approximately 135 eggs; however, there was a natural attrition rate of about 80% in first‐instar nymphs due to the nymph's inability to find a suitable feeding site. Feeding nymphs induced pit galls on young H. odorata leaves and were present on all trees examined during the study. The pre‐adult life cycle lasted approximately 13 days and adult life span approximately seven days. Several toxic insecticides were found to be effective for controlling T. hopeae, but a novel non‐toxic alternative was equally as effective. We discuss these methods and potential biological control measures.     

Temporal Changes in Population Dynamics of American Martens

ABSTRACT Population parameters of American martens (Martes Americana) are often monitored to guide management actions. In order to better understand changing marten population demographics, we estimated marten abundance and several population parameters on a portion of northeast Chichagof Island (NCI), Southeast Alaska, USA, using capture-mark–recapture methods in combination with radiotelemetry and compared these data with demographic estimates derived from the trapper catch from the larger NCI area. We found that capture probability remained relatively high across trapping sessions by using a standard live-trapping protocol, and we found no evidence of capture probability being consistently affected by population or environmental factors. Estimated marten numbers varied greatly over the period, ranging from a low of 14.1 martens (0.17/km²) during winter 1997–1998 to a high of 45.6 martens (0.55/km²) during winter 1995–1996. The annual trend was for decreasing numbers from winter 1990–1991 to winter 1992–1993, then increasing numbers through winter 1995–1996. By winter 1996–1997, numbers had dropped substantially and remained low through 1997–1998. All population parameters varied temporally, including annual survival (0.34–1.00), sex ratio (1.0–3.5), mean age (0.5–2.9), body condition (-0.08–1.35), and fecundity (0.44–2.70). Yearly trapper catches on NCI varied greatly from 19 to 354 martens (0.02 martens/km² to 0.31 martens/km²) because of changing trapper effort and marten abundance. We found mean ages of carcasses a good predictor of population mean age, but sex ratios were highly variable. Marten numbers and fecundity were strongly correlated with rodent abundance, especially long-tailed voles (Microtus longicaudus). By monitoring demographic parameters of the population or trapper-caught carcasses, managers can gain insight into temporal population dynamics. Also, total captures of individuals may provide a useful estimate of marten numbers without the expense of radiocollaring and tracking individuals because population estimates were highly correlated with number of individuals captured during a standard survey. Because of their high vulnerability to trapping, close monitoring of marten populations is important for the conservation and sustained-yield management of the species. A tracking strategy developed with input data on preseason abundance and age structure may be the best management approach, especially for small populations with limited immigration.     

Human impacts in soft‐sediment assemblages at Casey Station,East Antarctica: Spatial variation,taxonomic resolution and data transformation

Abstract Differences between marine soft‐sediment assemblages at disturbed (two waste dumps, a sewage outfall and a wharf) and control locations were found at Casey Station, Antarctica. These differences were significant against considerable background spatial variability. Core samples were collected by divers using a hierarchical, spatially nested sampling design incorporating four scales: (i) locations (thousands of metres apart); (ii) sites (hundreds of metres apart); (iii) plots (tens of metres apart); and (iv) among replicates within plots (approximately 1 metre apart). Control locations had greater species richness and diversity than disturbed locations and there were many taxa found at control locations that were not recorded at disturbed locations. Assemblages at disturbed locations were less variable than those at control locations. In contrast, populations of some dominant species were more variable at disturbed locations than at control locations. Significant variation in populations of individual taxa was also found at all scales and although greatest at the level of location, variation was also large at the smallest scale, between replicate cores, indicating significant small‐scale patchiness in populations of taxa. Patterns of assemblage structure were similar at fine (77 taxa) and medium (aggregated to 33 taxa) levels of taxonomic resolution, but changed at coarse levels of resolution (nine phyla). Soft‐sediment assemblages at Casey Station are markedly different from those reported from other areas of Antarctica. Assemblages at Casey are almost completely dominated by crustaceans (up to 99% total abundance) and polychaetes are rare or in very low abundances in most areas investigated in the region. This is also the first demonstration that small Antarctic research stations (population 20–50 people) may cause impacts that are detectable in the adjacent marine environment.     

Evolution of St Helena arborescent Astereae (Asteraceae): relationships of the genera Commidendrum and Melanodendron

The cladistic relationships of endemic Commidendrum (four species) and Melanodendron (one species) from St Helena were inferred from sequences of ITS1 and ITS2 of nuclear ribosomal DNA. Despite showing a range of morphological and ecological variation, the four species of Commidendrum , C. spurium , C. robustum , C. rotundifolium , and C. rugosum , form a closely related monophyletic group with percentage sequence divergence between 0.2 and 0.9%. Melanodendron integrifolium is sister to Commidendrum indicating that the two genera may have evolved from a common ancestor that arrived in St Helena via a single dispersal event. The closest relatives of Commidendrum and Melanodendron appear to be South African, in the predominantly shrubby genus Felicia , although further sampling of South African Astereae is required. We discuss the evolution and adaptive radiation of these rare and threatened species with particular reference to the possible role of heterochrony.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 144 , 69–83.     

Eucalypt plantings on farms benefit woodland birds in south‐eastern Australia

Abstract Most of the original forest and woodland cover on the western slopes of New South Wales and the northern plains of Victoria has been cleared for agriculture (wheat, sheep and cattle) and what remains is highly fragmented and modified by a long history of disturbance. Over the past three decades, native eucalypt trees and shrubs have been planted extensively in a part of this region to provide a range of environmental benefits. Our aim was to determine the extent to which these plantings could improve biological diversity in agricultural landscapes in south‐eastern Australia and to identify the variables influencing their effectiveness. We sampled birds at 120 sites encompassing the range of available patch sizes, stand ages, floristic and structural conditions, and habitat attributes for revegetated areas and remnants of native vegetation, and we compared these to nearby paddocks. Eucalypt plantings were found to provide significant improvements in bird population density compared with cleared or sparsely treed paddocks, and mixed eucalypt and shrub plantings had similar bird communities to remnant native forest and woodland in the region. Birds displayed a strong response to patch size, with both larger (≥5–20 ha) eucalypt plantings and larger (≥5–20 ha) remnants having more species and more individuals per unit area than smaller (<5 ha) patches of these vegetation types. Older (10–25 years) plantings had more bird species and individuals than young (<10 years) plantings. The distance from remnant forest and woodland (habitat connectivity) appeared to be an important variable influencing bird species richness in eucalypt plantings. The main differences were due to the greater numbers of species classified as woodland‐dependent in the larger‐sized patches of plantings and remnants. Eucalypt plantings provided useful habitat for at least 10 declining woodland‐dependent species, notably for the Speckled Warbler, Red‐capped Robin and Rufous Whistler. The Brown Treecreeper and Dusky Woodswallow appeared to be the species most limited by the extent of remnant forest and woodland in the region. Plantings of all shapes and sizes, especially those larger than 5 ha, have an important role to play in providing habitat for many bird species. Restoration efforts are more likely to be successful if eucalypt plantings are established near existing remnant vegetation.     

Remarkably preserved annelid worms from the La Meseta Formation (Eocene), Seymour Island, Antarctica

Abstract: Worm tubes, which exhibit the replaced tube-lining membrane, have been collected from the lowermost Lower Eocene Acantilados Allomember of the La Meseta Formation, Seymour Island, Antarctica. The discovery represents the oldest examples of preservation of the tube-lining membrane of tube-dwelling Polychaeta in the fossil record. A new genus and species, Caprascolex antarcticus , are described. The specimens are preserved as thin coatings of amorphous iron oxide on the inner surface of the moulds interpreted to be the replaced tube-lining membrane. Examination of the rarely described tube-lining mucosoid membrane in extant polychaetes shows that the fossils are nearly identical in morphology and scale to extant forms. These fossils record in remarkable detail the morphology of the tube-lining membrane, which appears to be composed of growth bands formed as the worm constructed the tube. The tube-lining is believed to have been originally preserved as pyrite, with subsequent oxidation to iron oxide. The tube-lining membrane of worm tubes possibly is known from only one other fossil occurrence.     

The publication and typification of Sir James Edward Smith's lichens in English Botany

A total of 391 lichens were written up in Smith's English Botany , of which 57 were new. All were illustrated by James Sowerby. The copyright dates are given, which should be accepted as those of publication. They range from 1793 until 1814, and paper watermarks show that reprintings occurred until c . 1818. The locations of the type specimens are given, many of which are part of the BM Botany Library, mounted together with Sowerby's original English Botany drawings, and therefore often overlooked. Their current taxonomic position is evaluated. Only 11 of the 57 new lichens have been placed in synonymy, which indicates that Smith was an excellent lichen taxonomist. Caloplaca borreri J.R.Laundon is a new name for Lepraria ochracea Turner & Borrer ex Sm., whilst Herteliana gagei (Sm.) J.R.Laundon is a new combination with priority over H. taylorii P.James, and Trapelia glebulosa (Sm.) J.R.Laundon replaces T. involuta (Taylor) Hertel. Species requiring author corrections are Caloplaca cerina (Hedw.) Th.Fr., Enterographa elaborata (Leight.) Coppins & P.James, Lecidella pulveracea (Flörke ex Th.Fr.) P.Syd., and Parmelia borreri Turner. Lichen daedaleus Sm. pre-dates Lecidea sorediata Ach. by 4 years, but has been proposed for rejection in order to retain the established name Pyxine sorediata (Ach.) Mont. Eight names remain undetermined, chiefly fungi in Spiloma.   © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 147 , 483–499.     

Coarse woody debris in Australian forest ecosystems: A review

Abstract Coarse woody debris (CWD) is the standing and fallen dead wood in a forest and serves an important role in ecosystem functioning. There have been several studies that include estimates of CWD in Australian forests but little synthesis of these results. This paper presents findings from a literature review of CWD and fine litter quantities. Estimates of forest‐floor CWD, snags and litter from the literature are presented for woodland, rainforest, open forest and tall open forest, pine plantation and native hardwood plantation. Mean mass of forest floor CWD in Australian native forests ranged from 19 t ha^?1 in woodland to 134 t ha^?1 in tall open forest. These values were generally within the range of those observed for similar ecosystems in other parts of the world. Quantities in tall open forests were found to be considerably higher than those observed for hardwood forests in North America, and more similar to the amounts reported for coniferous forests with large sized trees on the west coast of the USA and Canada. Mean proportion of total above‐ground biomass as forest floor CWD was approximately 18% in open forests, 16% in tall open forests, 13% in rainforests, and 4% in eucalypt plantations. CWD can be high in exotic pine plantations when there are considerable quantities of residue from previous native forest stands. Mean snag biomass in Australian forests was generally lower than the US mean for snags in conifer forests and higher than hardwood forest. These results are of value for studies of carbon and nutrient stocks and dynamics, habitat values and fire hazards.     

Whole Genome Amplification for Sequencing and Applications in Conservation Genetics

Abstract: We describe a method for rapidly amplifying whole genomes via a Phi29 DNA polymerase-mediated strand displacement reaction (SDR). Genomic amplification products derived from the SDR reaction resulted in high quantities of DNA suitable for polymerase chain reaction (PCR) amplification and sequencing of mitochondrial genomes. Control region sequences of DNA derived directly from PCR amplicons of extracted DNA were identical to those derived from PCR amplification of SDR genomic DNA. Effective SDR amplification and subsequent sequencing was successful across tissues sources ranging in age from 1 year to 19 years. Strand replacement reaction genomic amplification offers a means of obtaining large quantities of DNA from small amounts of tissue.