Effective monitoring of agriculture: a response

The development of effective agricultural monitoring networks is essential to track, anticipate and manage changes in the social, economic and environmental aspects of agriculture. We welcome the perspective of Lindenmayer and Likens (J. Environ. Monit., 2011, 13, 1559) as published in the Journal of Environmental Monitoring on our earlier paper, "Monitoring the World's Agriculture" (Sachs et al., Nature, 2010, 466, 558-560). In this response, we address their three main critiques labeled as 'the passive approach', 'the problem with uniform metrics' and 'the problem with composite metrics'. We expand on specific research questions at the core of the network design, on the distinction between key universal and site-specific metrics to detect change over time and across scales, and on the need for composite metrics in decision-making. We believe that simultaneously measuring indicators of the three pillars of sustainability (environmentally sound, social responsible and economically viable) in an effectively integrated monitoring system will ultimately allow scientists and land managers alike to find solutions to the most pressing problems facing global food security.     

An In Situ Bioreactor for the Treatment of Petroleum Hydrocarbons in Groundwater

Two pilot tests of an aerobic in situ bioreactor (ISBR) have been conducted at field sites contaminated with petroleum hydrocarbons. The two sites differed with respect to hydrocarbon concentrations. At one site, concentrations were low but persistent, and at the other site concentrations were high enough to be inhibitory to biodegradation. The ISBR unit is designed to enhance biodegradation of hydrocarbons by stimulating indigenous microorganisms. This approach builds on existing Bio‐Sep^® bead technology, which provides a matrix that can be rapidly colonized by the active members of the microbial community and serves to concentrate indigenous degraders. Oxygen and nutrients are delivered to the bioreactor to maintain conditions favorable for growth and reproduction, and contaminated groundwater is treated as it is circulated through the bed of Bio‐Sep^® beads. Groundwater moving through the system also transports degraders released from Bio‐Sep^® beads away from the bioreactor, potentially increasing biodegradation rates throughout the aquifer. Groundwater sampling, Bio‐Traps, and molecular biological tools were used to assess ISBR performance during the two pilot tests. Groundwater monitoring indicated that contaminant concentrations decreased at both sites, and the microbial data suggested that these decreases were due to degradation by indigenous microorganisms rather than dilution or dispersion mechanisms. Taken together, these lines of evidence showed that the ISBR system effectively increased the number and activity of indigenous microbial degraders and enhanced bioremediation at the test sites. © 2013 Wiley Periodicals, Inc.     

Dietary exposure to technical hexabromocyclododecane (HBCD) alters courtship, incubation and parental behaviors in American kestrels (Falco sparverius)

Hexabromocyclododecane (HBCD) is a high production volume brominated flame retardant that has been detected in the environment and wildlife at increasing concentrations. This study was designed to determine potential effects of dietary exposure to environmentally relevant levels of HBCD on behavior during reproduction in captive American kestrels. Twenty kestrel pairs were exposed to 0.51 μg technical HBCD g⁻¹ kestrel d⁻¹ from 4 weeks prior to pairing until chicks hatched (∼75 d). Ten pairs of controls received the safflower oil vehicle only and were used for comparison. During the courtship period the chitter-calls were reduced in both sexes (p = 0.038) and females performed fewer bonding displays (p = 0.053). Both sexes showed a propensity to be less active than controls during courtship. The reduction in male courtship behavior was correlated with reduced courtship behaviors of females (p ? 0.008) as well as reduced egg mass (p = 0.019). During incubation, nest temperatures of treatment pairs were lower at mid-incubation (p = 0.038). HBCD-exposed males performed fewer key parental behaviors when rearing nestlings, including entering the nest-box, pair-bonding displays and food-retrievals. HBCD-exposed females appeared to compensate for the reduced parental behavior of their mates by performing these same behaviors more frequently than controls (p = 0.004, p = 0.027, p = 0.025, respectively). This study demonstrates that HBCD affects breeding behavior in American kestrels throughout the reproductive season and behavioral alterations were linked to reproductive changes (egg size). This is the first study to report HBCD effects on reproductive behavior in any animal model.     

Earthquake mortality in Pakistan

A strong earthquake, measuring 7.6 on the Richter scale, hit northern Pakistan on 8 October 2005, causing massive destruction, including an official death toll of 73,276. Four cross-sectional surveys were performed in late 2005 to assess mortality before the event, on the day, and subsequently. Two surveys were community-based and two were situated in camps for internally displaced persons. Crude mortality rates were low in the 3.5 months preceding the earthquake (less than 0.1 deaths per 10,000 per day) and slightly higher in the six-to-eight weeks after the earthquake (ranging from 0.10–0.43 per 10,000 per day). On 8 October 2005, approximately two per cent of the population in one community survey died and around five per cent in the other three surveys. Children less than five years and adults more than or equal to 50 years tended to have a higher risk of mortality on the day of the disaster. These results corroborate the high mortality caused by the earthquake.     

Physical variability among nest foundresses in the polygynous social wasp,Polistes annularis

Summary An individual's rank in a dominance hierarchy is often based on size or weight, especially in insects. Foundresses of the social wasp, Polistes annularis, vary greatly in size as measured by wing length, dry weight, fat weight, and residue weight after fat has been extracted. Females that emerged from the same nest are much more similar in size to each other than they are to females that emerged from other nests. Within nests however queens are usually larger than their subordinates. Queens that emerged from one nest may be smaller than subordinates that emerged from another nest. We found no evidence of a group of females that are forced into being subordinates because of inadequate feeding as larvae. Females are also probably not attempting to begin new nests with females as different in size as possible from themselves since means and variances of winglength of females on new nests do not differ from those of all females emerging from that natal nest.     

Butyltin and copper monitoring in a Northern Chesapeake Bay marina and river system in 1989: An assessment of tributyltin legislation

This study was designed to: (1) evaluate dibutyltin (DBT) and tributyltin (TBT) bi-weekly in the water column for four months during the peak boating season (June–September, 1989) at seven stations in the Back Creek and Severn River area of Maryland waters of Chesapeake Bay; (2) compare butyltin values from the 1989 study with values obtained from a similar butyltin monitoring study conducted in 1988 (after Maryland TBT legislation) and 1986 (before Maryland TBT legislation); (3) determine the extent of TBT paint use in the Back Creek area by surveying boat owners; (4) determine dissolved copper concentrations from three of the seven stations bi-weekly during the four-month study; and (5) compare dissolved copper concentrations at these stations with previous copper data collected in 1988.Mean four-month DBT concentrations ranged from 10 to 73 ng/L at the seven stations. Highest DBT concentrations occurred at Station 1 in a marina; lowest concentrations occurred at Station 7 in the Severn River. Mean four-month TBT concentrations ranged from 177 ng/L at Station 1 (marina) to 21 ng/L at Station 7 (Severn River). Maximum TBT concentrations of 361 and 570 ng/L occurred at marina SDtations 1 and 3, respectively. Temporal trends in both DBT and TBT (station mean concentrations by date) showed that peak concentrations occurred during the early part of the boating season followed by reductions in late summer and early fall. Spike concentrations of both DBT (117 and 62 ng/L) and TBT (308 and 366 ng/L) were reported on two sampling dates near a boat maintenance facility in Back Creek.There was a significant reduction in DBT concentrations from 1986 to 1989 when date was treated as a fixed effect. However, TBT concentrations were not significantly reduced between 1986 and 1989 when mean concentrations of TBT were averaged across stations and dates for each year. A significant reduction was reported at Station 1 (marina station) when each station was examined for differences between years. TBT was also reported to significantly decrease (p=0.0442) at Station 7 between 1988 and 1989. A boat owner survey in the study area showed that 6% of the recreational boats that were surveyed were painted with TBT paint in 1989. This was a significant decrease in TBT paint use from the previous year when 31% of recreational boat owners surveyed used TBT paints.An evaluation of dissolved copper concentrations at three stations in the study area in 1989 showed that mean concentrations from bi-weekly sampling for four months was 10 g/L at Station 1, 7.8 g/L at Station 4 and 2.7 g/L at Station 7. Copper concentrations decreased with distance away from the Back Creek marinas. Copper concentrations at all three stations were significantly lower in 1989 than in 1988.     

Financial viability of reforesting reclaimed surface mined lands, the burden of site conversion costs, and carbon payments as reforestation incentives

US Federal law mandates that mined land be returned by mine operators to a condition capable of supporting its pre-mining use or a higher use. Previously forested lands have commonly been reclaimed to hayland/pasture or wildlife habitat, and most of these lands have been abandoned from management and rendered non-productive. This situation has left landowners in the position of converting these reclaimed mined lands to forests at a later date, if they choose to make them economically productive. Such land-use conversion, however, comes with a substantial up-front cost to the landowner, which makes the financial viability of such a conversion questionable. We examine the financial viability of reforestation of these previously reclaimed mine lands by calculating land expectation value (LEV) under a range of conditions that include forest type, site quality, and reforestation intensity. We find that conversion to white pine is viable on higher quality sites under low to moderate interest rates with low or high timber prices, but conversion to mixed hardwoods is only profitable under the high price scenario with low interest rates, and only on higher quality sites. We also consider the implications of a shift in reforestation burden from the landowner to the mine operator, and results suggest that including costs of reforestation as part of the mining operation creates a financially viable forest enterprise for landowners under all scenarios for both white pine and mixed hardwoods. Two forms of carbon payments that could encourage reforestation of previously reclaimed mined lands also are examined: an annual payment based upon the total accumulated carbon found on-site in a given year, and an annual payment based on only the increment of carbon storage each year. Our carbon payment results indicate that annual values of up to $5.17 per ton of carbon stored in hardwoods and $9.39 per ton of carbon stored in pines would be required to make reforestation profitable under the poorest conditions (high interest rates, low prices, and poor quality site) when the payment is based on accumulated on-site carbon, although lower values are required under more favorable scenarios. Payments that are based upon the annual increment of carbon must fall in the range of $8.66–$71.88 per ton of carbon stored in hardwoods and $0–$83.29 per ton of carbon stored in pines to make reforestation financially viable.     

Prediction and uncertainty source analysis of the spatial and temporal disturbance from off-road vehicular traffic in a complex ecosystem

Vehicle use during military training activities results in soil disturbance and vegetation loss. The capacity of lands to sustain training is a function of the sensitivity of lands to vehicle use and the pattern of land use. The sensitivity of land to vehicle use has been extensively studied. Less well understood are the spatial patterns of vehicle disturbance. Since disturbance from off-road vehicular traffic moving through complex landscapes varies spatially, a spatially explicit nonlinear regression model (disturbance model) was used to predict the pattern of vehicle disturbance across a training facility. An uncertainty analysis of the model predictions assessed the spatial distribution of prediction uncertainty and the contribution of different error sources to that uncertainty.For the most part, this analysis showed that mapping and modeling process errors contributed more than 95% of the total uncertainty of predicted disturbance, while satellite imagery error contributed less than 5% of the uncertainty. When the total uncertainty was larger than a threshold, modeling error contributed 60% to 90% of the prediction uncertainty. Otherwise, mapping error contributed about 10% to 50% of the total uncertainty. These uncertainty sources were further partitioned spatially based on other sources of uncertainties associated with vehicle moment, landscape characterization, satellite imagery, etc.