Restoring Forest Landscapes: Important Lessons Learnt

Forest restoration at large scales, or landscapes, is an approach that is increasingly relevant to the practice of environmental conservation. However, implementation remains a challenge; poor monitoring and lesson learning lead to similar mistakes being repeated. The World Wildlife Fund (WWF), the global conservation organization, recently took stock of its 10 years of implementation of forest landscape restoration. A significant body of knowledge has emerged from the work of the WWF and its partners in the different countries, which can be of use to the wider conservation community, but for this to happen, lessons need to be systematically collected and disseminated in a coherent manner to the broader conservation and development communities and, importantly, to policy makers. We use this review of the WWF’s experiences and compare and contrast it with other relevant and recent literature to highlight 11 important lessons for future large-scale forest restoration interventions. These lessons are presented using a stepwise approach to the restoration of forested landscapes. We identify the need for long-term commitment and funding, and a concerted and collaborative effort for successful forest landscape restoration. Our review highlights that monitoring impact within landscape-scale forest restoration remains inadequate. We conclude that forest restoration within landscapes is a challenging yet important proposition that has a real but undervalued place in environmental conservation in the twenty-first century.     

The introduction of Littorina littorea to British Columbia, Canada: potential impacts and the importance of biotic resistance by native predators

Although the establishment and spread of non-indigenous species depends upon survival in the face of novel environmental conditions and novel biological interactions, relatively little attention has been focused on the specific role of native predators in limiting invasion success. The European common periwinkle, Littorina littorea, was recently introduced to the Pacific coast of Canada and provides a case study of an introduction into an area with an important predator guild (sea stars) that is functionally minor in the invader’s native habitat. Here, we assess the likelihood of establishment, spread, and negative ecological impact of this introduced gastropod, with an emphasis on the role of native sea stars as agents of biotic resistance. Size frequency distributions and local market availability suggest that L. littorea was most likely introduced via the live seafood trade. Non-native hitchhikers (e.g., the trematode Cryptocotyle lingua) were found on/in both market and field specimens. Laboratory studies and field observations confirmed that L. littorea can survive seasonal low salinity in Vancouver, British Columbia. Periwinkles also readily consumed native Ulva, suggesting that periwinkles could impact native communities via herbivory or resource competition. Unlike native gastropods, however, L. littorea lacked behavioural avoidance responses to Northeast Pacific predatory sea stars (Pisaster ochraceus and Pycnopodia helianthoides), and sea star predation rates on L. littorea were much higher than predation rates on native turban snails (Chlorostoma funebralis) in common garden experiments. We therefore expect periwinkle establishment in British Columbia to be limited to areas with low predator density, as is seen in its field distribution to date. We caution that this conclusion may understate the importance of the L. littorea introduction if it also serves as a vector for additional non-indigenous species such as C. lingua.     

Background and temperature effects on Uca panacea color change

Organismal coloration is used for communication, camouflage, and thermoregulation. These functions of body coloration may impose conflicting demands upon color-changing organisms. Here, we examined interacting thermoregulatory and camouflage color change responses when fiddler crabs Uca panacea were subject to simultaneously changing temperatures (10, 25, 40 °C) and backgrounds (black, white). Crab coloration lightened on a white background and at high temperatures and darkened on a black background and at low temperatures, reflecting the camouflage and thermoregulatory functions of color change. Synergistic background and temperature treatments (i.e., hot/white or cold/black) induced strong color change responses. When temperature and background were in conflict (i.e., hot/black or cold/white), responses to background coloration constrained thermoregulatory color change such that carapace coloration did not change. Such conflicts are likely to be common in nature, especially in highly heterogeneous environments. Throughout the experiment, males remained lighter than females and showed a greater response to the hot/white treatment, driven by a stronger response to high temperatures. These differences may reflect the physiological, morphological, and behavioral differences associated with sexual selection and sexual dimorphism in this species.     

Corridors promote fire via connectivity and edge effects

Landscape corridors, strips of habitat that connect otherwise isolated habitat patches, are commonly employed during management of fragmented landscapes. To date, most reported effects of corridors have been positive; however, there are long-standing concerns that corridors may have unintended consequences. Here, we address concerns over whether corridors promote propagation of disturbances such as fire. We collected data during prescribed fires in the world's largest and best replicated corridor experiment (Savannah River Site, South Carolina, USA), six -50-ha landscapes of open (shrubby/herbaceous) habitat within a pine plantation matrix, to test several mechanisms for how corridors might influence fire. Corridors altered patterns of fire temperature through a direct connectivity effect and an indirect edge effect. The connectivity effect was independent of fuel levels and was consistent with a hypothesized wind-driven "bellows effect." Edges, a consequence of corridor implementation, elevated leaf litter (fuel) input from matrix pine trees, which in turn increased fire temperatures. We found no evidence for corridors or edges impacting patterns of fire spread: plots across all landscape positions burned with similar probability. Impacts of edges and connectivity on fire temperature led to changes in vegetation: hotter-burning plots supported higher bunch grass cover during the field season after burning, suggesting implications for woody/herbaceous species coexistence. To our knowledge, this represents the first experimental evidence that corridors can modify landscape-scale patterns of fire intensity. Corridor impacts on fire should be carefully considered during landscape management, both in the context of how corridors connect or break distributions of fuels and the desired role of fire as a disturbance, which may range from a management tool to an agent to be suppressed. In our focal ecosystem, longleaf pine woodland, corridors might provide a previously unrecognized benefit during prescribed burning activities, by promoting fire intensity, which may assist in promoting plant biodiversity.     

Atmospheric deposition of pesticides to an agricultural watershed of the Chesapeake Bay

The Choptank River watershed, located on the Delmarva Peninsula of the Chesapeake Bay, is dominated by agricultural land use, which makes it vulnerable to runoff and atmospheric deposition of pesticides. Agricultural and wildlife areas are in close proximity and off-site losses of pesticides may contribute to toxic effects on sensitive species of plants and animals. High-volume air samples (n = 31) and event-based rain samples (n = 71) were collected from a single location in the watershed representing regional background conditions. Surface water samples were collected from eight stations in the tidal portion of the river on five occasions during 2000. Chlorothalonil, metolachlor, atrazine, simazine, endosulfan, and chlorpyrifos were frequently detected in the air and rain, with maximal concentrations during the period when local or regional crops were planted. The wet deposition load to the watershed was estimated at 150 +/- 16, 61 +/- 7, and 51 +/- 6 kg yr(-1) for chlorothalonil, metolachlor, and atrazine, respectively. The high wet deposition load compared with the estimated annual usage for chlorothalonil (13%) and endosulfan (14-90%) suggests an atmospheric source from outside the watershed. Net air-water gas exchange fluxes for metolachlor varied from -44 +/- 19 to 9.3 +/- 4.1 ng m(-2) d(-1) with negative values indicating net deposition. Wet deposition accounted for 3 to 20% of the total metolachlor mass in the Choptank River and was a more important source to the river than gas exchange. Estimates of herbicide flux presented here are probably a low estimate and actual rates may be significantly higher in areas closer to pesticide application.     

Effects of different management strategies on long-term trends of Australian threatened and near-threatened mammals

Monitoring is critical to assess management effectiveness, but broadscale systematic assessments of monitoring to evaluate and improve recovery efforts are lacking. We compiled 1808 time series from 71 threatened and near-threatened terrestrial and volant mammal species and subspecies in Australia (48% of all threatened mammal taxa) to compare relative trends of populations subject to different management strategies. We adapted the Living Planet Index to develop the Threatened Species Index for Australian Mammals and track aggregate trends for all sampled threatened mammal populations and for small (<35 g), medium (35–5500 g), and large mammals (>5500 g) from 2000 to 2017. Unmanaged populations (42 taxa) declined by 63% on average; unmanaged small mammals exhibited the greatest declines (96%). Populations of 17 taxa in havens (islands and fenced areas that excluded or eliminated introduced red foxes [Vulpes vulpes] and domestic cats [Felis catus]) increased by 680%. Outside havens, populations undergoing sustained predator baiting initially declined by 75% but subsequently increased to 47% of their abundance in 2000. At sites where predators were not excluded or baited but other actions (e.g., fire management, introduced herbivore control) occurred, populations of small and medium mammals declined faster, but large mammals declined more slowly, than unmanaged populations. Only 13% of taxa had data for both unmanaged and managed populations; index comparisons for this subset showed that taxa with populations increasing inside havens declined outside havens but taxa with populations subject to predator baiting outside havens declined more slowly than populations with no management and then increased, whereas unmanaged populations continued to decline. More comprehensive and improved monitoring (particularly encompassing poorly represented management actions and taxonomic groups like bats and small mammals) is required to understand whether and where management has worked. Improved implementation of management for threats other than predation is critical to recover Australia's threatened mammals.     

Decision-support tools for dynamic management

Spatial management is a valuable strategy to advance regional goals for nature conservation, economic development, and human health. One challenge of spatial management is navigating the prioritization of multiple features. This challenge becomes more pronounced in dynamic management scenarios, in which boundaries are flexible in space and time in response to changing biological, environmental, or socioeconomic conditions. To implement dynamic management, decision-support tools are needed to guide spatial prioritization as feature distributions shift under changing conditions. Marxan is a widely applied decision-support tool designed for static management scenarios, but its utility in dynamic management has not been evaluated. EcoCast is a new decision-support tool developed explicitly for the dynamic management of multiple features, but it lacks some of Marxan's functionality. We used a hindcast analysis to compare the capacity of these 2 tools to prioritize 4 marine species in a dynamic management scenario for fisheries sustainability. We successfully configured Marxan to operate dynamically on a daily time scale to resemble EcoCast. The relationship between EcoCast solutions and the underlying species distributions was more linear and less noisy, whereas Marxan solutions had more contrast between waters that were good and poor to fish. Neither decision-support tool clearly outperformed the other; the appropriateness of each depends on management purpose, resource-manager preference, and technological capacity of tool developers. Article impact statement: Marxan can function as a decision-support tool for dynamic management scenarios in which boundaries are flexible in space and time.     

Sodium bisulfate and a sodium bisulfate/tannin mixture decreases pH when added to an in vitro incubated poultry cecal or fecal contents while reducing Salmonella Typhimurium marker strain survival and altering the microbiome

The objective of the present study was to investigate the ability of animal feed-grade sodium bisulfate (SBS) and a mixture of sodium bisulfate/tannin to inhibit the growth of Salmonella using an anerobic in vitro mixed cecal culture to mimic the conditions within the chicken cecum. An initial inoculum of Salmonella Typhimurium was introduced to an anerobic dilution solution containing 1/3000 diluted cecal bacteria and solids consisting of ground chicken feed and different percentages of solid SBS or SBS/tannin, and surviving organisms were enumerated. Two different experimental designs were employed. In the “unadapted” treatment, the S. Typhimurium was added at the beginning of the culture incubation along with cecal bacteria and chicken feed/SBS or chicken feed/SBS/tannin. In the “adapted” treatment, S. Typhimurium was added after a 24 hour pre-incubation of the cecal bacteria with the chicken feed/SBS or chicken feed/SBS/tannin. Adding SBS resulted in reduction of pH in the cultures which paralleled with the reduction of S. Typhimurium. The SBS alone was found to be inhibitory to S. Typhimurium in the adapted treatment at all concentrations tested (0.25, 0.5, and 0.75%), and the degree of inhibition was concentration-dependent. Salmonella Typhimurium was completely killed in the adapted culture with 0.5% SBS after 24 and 48 h. The SBS/tannin mixture was less inhibitory than SBS alone at the same concentrations in side-by-side comparisons. Testing at a 0.5% SBS concentration, chicken age had little or no effect on log reduction of S. Typhimurium relative to age-matched control cultures without SBS, but age did affect the absolute number of S. Typhimurium surviving, with the greatest decreases occurring at 2 and 4 weeks of age (approx. 10³ S. Typhimurium surviving) compared to 6 weeks of age (approx. 10⁵ Salmonella surviving). Microbiome analysis with an Illumina MiSeq platform was conducted to investigate bacterial compositional changes related to the addition of SBS. The relative abundance of Firmicutes (at the phylum level) was decreased, and genera Lactobacillus and Faecalibacterium were increased when SBS was added to the anaerobic mixed culture containing either fecal or cecal material. The antimicrobial action of feed-grade SBS may represent a potential pre-harvest control measure for Salmonella in poultry production.     

Human maternal and umbilical cord blood concentrations of polybrominated diphenyl ethers

Polybrominated diphenyl ethers (PBDEs), widely used as flame retardants in commercial products, have become ubiquitous environmental contaminants. Although adult human exposure to PBDEs is well documented, developmental exposure is less well characterized. The objectives of this study were to measure maternal and fetal exposure to nine PBDE congeners and to investigate potential associations with birth weight. PBDE congeners were quantified in maternal serum at 24-28 weeks of pregnancy, delivery, and umbilical cord serum (UCS) by gas chromatography-mass spectrometry (GC/MS/MS). Complete blood sample sets were obtained from 97 pregnant women (mean age 33.1 ± 0.5 years). PBDE-28, -47 and -99 were quantified in all samples tested and PBDE-47 was the most abundant congener measured in both maternal (mid-pregnancy and delivery samples geometric mean = 26.9 and 26.9, respectively) and UCS (GM = 56.0 ng g⁻¹ lipid). The UCS concentration for all congeners with the exception of PBDE-153 was higher vs. maternal delivery samples (p < 0.001). Only the UCS concentration of PBDE-17 and -99 were significantly associated (β = −49.860, p = 0.032, and β = −3.645, p = 0.05) with birth weight. However, after adjustment for potential confounders only the association between PBDE-99 and birth weight remained significant (β = −3.951 and p = 0.016). We conclude that: the fetus is exposed to PBDEs from at least the second trimester of pregnancy onward; PBDE congeners are higher in UCS compared to maternal serum samples collected at delivery; and that developmental PBDE exposure is potentially associated with lower birth weight.