Landscape Factors Associated with Subterranean Termite (Isoptera: Rhinotermitidae) Treatments and Colony Structure in Residential Subdivisions

Subterranean termites (Isoptera: Reticulitermes) are common structural pests, but it is not well known how landscape factors are associated with urban colonization. This study examined patterns of subterranean termite colonization in 13 mid-Missouri residential subdivisions. Ten- and 20-year-old homes built on historically agricultural and forested landscapes were inspected for treatment by termiticide application or bait stations. Contemporary and historical aerial imagery were analyzed using GIS software, and patterns of colonization were compared among subdivisions. The genetic structure of termite colonies collected in undeveloped landscapes and residential subdivisions was compared using microsatellite DNA. Twenty-year-old subdivisions had significantly higher treatment proportions than 10-year-old subdivisions. At year 10, historically forested subdivisions had a higher treatment proportion than historically agricultural subdivisions. By year 20, there was no significant difference in treatment proportion between historical landscape types, indicating that subdivisions built on agricultural landscapes eventually catch up to subdivisions built on forest landscapes. Although there was not strong statistical support, treated homes in historically agricultural subdivisions tended to be close to forest patches, but there was less of an association in historically forested subdivisions. Colonies in undeveloped landscapes were more inbred compared to colonies in residential subdivisions, indicating that colonies sampled in subdivisions had fewer secondary reproductive and were potentially younger than those sampled in undeveloped landscapes. This study provides some correlative support for the role of dispersing alates as urban colonizers, because treatments were often located at relatively long distances from undisturbed forest patches in historically agricultural subdivisions

Growth of two peat-forming mosses in subarctic mires: species interactions and effects of simulated climate change

In patches of co-occurring species in natural plant communities, there is a finely poised balance between species in the ways in which they respond to prevailing moisture and temperature regimes. However, environmental change scenarios, in which temperature, moisture and ultraviolet-B radiation are suggested to increase, may favour one of the species. The imbalance is likely to occur at the levels of interactions between patches of the different species and at the shoot level when neighbouring shoots belong to different species. We increased temperature and UV-B in a two-way factorial experiment and increased water supply independently in two subarctic mire communities dominated by the mosses Sphagnum fuscum and Dicranum elongatum. The effects of simulated increase in UV-B were studied using two separate radiation systems, i.e. a square wave system and a modulated system. When precipitation was enhanced, both species showed an increase in growth but this was not sustained beyond 5 mm per day. S. fuscum showed a 50 greater response to enhanced precipitation than did D. elongatum, as would be expected from their habitat preferences. Under ambient temperature, S. fuscum grew 67 faster than D. elongatum and this relative difference in response was maintained after one year under a temperature enhancement. The response by species over the winter period was moderated by their neighbours. S. fuscum growth was enhanced when it grew next to D. elongatum whereas D. elongatum grew better with neighbours of its own species. Increased temperature and UV-B radiation did not affect the interaction between the species. Although a balance was maintained between the two species over the short duration of the experiment, potential was shown for an imbalance to occur over longer periods and particularly if winter warming and precipitation are greater than those in summer. During the peak growing season 20 increased UV-B over ambient had a negative effect on S. fuscum under increased temperature but there were no overall seasonal effects on either species, irrespective of method of UV supplementation

Ab initio characterization of several states of nitroxylium (NO 3 + ). Comparison of fragmentation energies of nitroxylium, nitroxyl (NO 3 ), and nitrate

Ab initio calculations have been performed at the self-consistent field (HF) level, and its perturbative extensions up to fourth-order (MPn), for several electronic states of nitroxylium (NO 3 + ) as well as for a large number of reference species. Geometries are optimized at the HF/DZ and HF/DZP levels (double zeta and double zeta plus polarization bases). The ground state is found to be the D 3 h 1 A 1 ′ state, with the C 2 v 1 A 1 (closed Y ) state higher by 0.94 eV. The relationship between adding electrons or oxygen atoms to NO + and NO 2 + is explored, especially in relation to fragmentation energies of NO 3 ± q ( q = 0 or 1). A comparison is drawn between NO 3 + and two isoelectronic species, CO 3 and C(CH 2 ) 3 , where no surprises are found.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/38282/1/540120113_ftp.pd

Effect of Terrain Characteristics on Soil Organic Carbon and Total Nitrogen Stocks in Soils of Herschel Island, Western Canadian Arctic

Permafrost landscapes experience different disturbances and store large amounts of organic matter, which may become a source of greenhouse gases upon permafrost degradation. We analysed the influence of terrain and geomorphic disturbances (e.g. soil creep, active-layer detachment, gullying, thaw slumping, accumulation of fluvial deposits) on soil organic carbon (SOC) and total nitrogen (TN) storage using 11 permafrost cores from Herschel Island, western Canadian Arctic. Our results indicate a strong correlation between SOC storage and the topographic wetness index. Undisturbed sites stored the majority of SOC and TN in the upper 70 cm of soil. Sites characterised by mass wasting showed significant SOC depletion and soil compaction, whereas sites characterised by the accumulation of peat and fluvial deposits store SOC and TN along the whole core. We upscaled SOC and TN to estimate total stocks using the ecological units determined from vegetation composition, slope angle and the geomorphic disturbance regime. The ecological units were delineated with a supervised classification based on RapidEye multispectral satellite imagery and slope angle. Mean SOC and TN storage for the uppermost 1 m of soil on Herschel Island are 34.8 kg C m-2 and 3.4 kg N m-2, respectively. Copyright © 2015 John Wiley & Sons, Ltd