Diversity2015, 7(3), 318-341; doi:10.3390/d7030318 - published 25 August 2015 Show/Hide Abstract
Abstract: Biodiversity-friendly farming is a growing area of discussion among farmers, as well as in government departments and non-government organizations interested in conservation on private land. Those seeking to encourage biodiversity on farms must understand the production challenges presented by wildlife. Such species destroy agricultural commodities or present threats to family, pets, or infrastructure. A survey of farmers in the Canadian Maritime provinces sought to understand the drivers of tolerance. Our results demonstrated that estimated monetary losses from a species were largely unrelated to the perceived acceptability of those losses. Rather, the type of nuisance—damage to crops/property or threat to the safety of people, pets, or livestock—determined whether a loss would be perceived as acceptable and if that acceptability would influence tolerance. For damaging species, the perception of cultural benefits seemed able to convert high estimated economic losses to acceptable ones, for overall tolerance. For threatening species, however, minor perceived financial losses seemed augmented by low perceived benefits and made unacceptable, leading to intolerance. Female, older, and part-time farmers were most likely to identify threatening species as a nuisance. The use of an elicitation-based survey design provided novel insight as a result of the lack of prompts, but also presented analytical challenges that weakened predictive power. Recommendations are given for further research and management.
Diversity2015, 7(3), 307-317; doi:10.3390/d7030307 - published 20 August 2015 Show/Hide Abstract
Abstract: The loss of global biological diversity continues despite on-going conservation efforts. Agriculture is the major terrestrial land use in Europe and any conservation efforts to protect biological diversity must address sustainable use of these food production systems. Using Ireland, within the European Union policy framework, as an example, the declines in farmland birds are discussed. The opportunities afforded to farmland bird conservation as a result of the recent reform to the Common Agricultural Policy (CAP) are outlined. The potential for revised and refined CAP, specifically agri-environment schemes, to deliver benefits for biodiversity and for farmland bird species within Irish agricultural ecosystems is explored. Despite all the efforts to date and the significant resources invested in implementing agri-environment measures and schemes, few attempts have been made to collect monitoring and surveillance data with which to quantitatively assess the effectiveness of schemes, and measures that are designed to assist in the recovery of farmland biodiversity, including bird species, in Ireland.
Diversity2015, 7(3), 295-306; doi:10.3390/d7030295 - published 30 July 2015 Show/Hide Abstract
Abstract: Habitat fragmentation can promote patches of small and isolated populations, gene flow disruption between those populations, and reduction of local and total genetic variation. As a consequence, these small populations may go extinct in the long-term. The ocelot (Leopardus pardalis), originally distributed from Texas to southern Brazil and northern Argentina, has been impacted by habitat fragmentation throughout much of its range. To test whether habitat fragmentation has already induced genetic differentiation in an area where this process has been documented for a larger felid (jaguars), we analyzed molecular variation in ocelots inhabiting two Atlantic Forest fragments, Morro do Diabo (MD) and Iguaçu Region (IR). Analyses using nine microsatellites revealed mean observed and expected heterozygosity of 0.68 and 0.70, respectively. The MD sampled population showed evidence of a genetic bottleneck under two mutational models (TPM = 0.03711 and SMM = 0.04883). Estimates of genetic structure (FST = 0.027; best fit of k = 1 with STRUCTURE) revealed no meaningful differentiation between these populations. Thus, our results indicate that the ocelot populations sampled in these fragments are still not significantly different genetically, a pattern that strongly contrasts with that previously observed in jaguars for the same comparisons. This observation is likely due to a combination of two factors: (i) larger effective population size of ocelots (relative to jaguars) in each fragment, implying a slower effect of drift-induced differentiation; and (ii) potentially some remaining permeability of the anthropogenic matrix for ocelots, as opposed to the observed lack of permeability for jaguars. The persistence of ocelot gene flow between these areas must be prioritized in long-term conservation planning on behalf of these felids.
Diversity2015, 7(3), 270-294; doi:10.3390/d7030270 - published 30 July 2015 Show/Hide Abstract
Abstract: Over the last half century the Iberian peninsula has seen the large scale planting of exotic gum trees (Eucalyptus sp.) therewith reducing space for native wildlife. An additional effect of the gum tree plantations may be the lowering of the water table in adjacent streams, to which amphibian species with a larval niche in the running sections of small streams would be especially susceptible. In northwestern Iberia that niche is occupied by the Golden-striped salamander, Chioglossa lusitanica. I here report on the demographic trends of two C. lusitanica populations over a forty-year period, in two areas of one mountain range near Porto in northwestern Portugal. In both areas advantage was taken of the migration pattern of C. lusitanica to sites for aestivation and breeding in summer and fall. The area of the Silveirinhos brook was transformed in a plantation of gum trees shortly after the research started, while the area of Poço do Inferno remained virtually unaffected. At Silveirinhos the adult C. lusitanica population declined by one or two orders of magnitude, from ca. 1500 individuals to less than 50 at present. Demographic models that operate under a uniform larval mortality yielded population sizes that are compatible with field observations, including the late onset of the decline at 14 or more years after the planting of the gum trees and the near-extinction at year 32. An alternative reason for the relatively recent population collapse of C. lusitanica may have been disease, but no sick individuals or corpses have become available for clinical investigation. Conversely, the control population at Poço do Inferno increased in size by a factor of five or more. These data support the hypothesis that gum tree plantations have a strong negative effect on C. lusitanica. The population size increase at Poço do Inferno is probably attributable to the installation of wastewater treatment in the adjacent town of Valongo, with a discharge in the Simão river and closely connected to Poço do Inferno. This result suggests that the Simão river contributes to the Poço do Inferno population and that medium-large streams may constitute prime C. lusitanica habitat. Larval mortalities estimated for stable and declining populations are remarkable close (0.69 and 0.73, respectively), but dissimilar to the larval mortality at ca. 0.51 of an increasing population such as at Poço do Inferno. Suggestions for further research include (i) the continued monitoring of the Silveirinhos population with inspections at 5–10 year intervals, and (ii) checking for the persistence of C. lusitanica populations in and around gum tree plantations where the species was reported decades ago.
Diversity2015, 7(3), 242-269; doi:10.3390/d7030242 - published 10 July 2015 Show/Hide Abstract
Abstract: The Sundarbans is a deltaic mangrove forest, formed about 7000 years ago by the deposition of sediments from the foothills of the Himalayas through the Ganges river system, and is situated southwest of Bangladesh and south of West Bengal, India. However, for the last 40 years, the discharge of sediment-laden freshwater into the Bay of Bengal through the Bangladesh part of the Sundarbans Mangrove Forests (BSMF) has been reduced due to a withdrawal of water during the dry period from the Farakka Barrage in India. The result is two extremes of freshwater discharge at Gorai, the feeding River of the BSMF: a mean minimum monthly discharge varies from 0.00 to 170 m3·s−1 during the dry period with a mean maximum of about 4000 to 8880 m3·s−1 during the wet period. In the BSMF, about 180 km downstream, an additional low discharge results in the creation of a polyhaline environment (a minimum of 194.4 m3·s−1 freshwater discharge is needed to maintain an oligohaline condition) during the dry period. The Ganges water carries 262 million ton sediments/year and only 7% is diverted in to southern distributaries. The low discharge retards sediment deposition in the forestlands’ base as well as the formation of forestlands. The increase in water flow during monsoon on some occasions results in erosion of the fragile forestlands. Landsat Satellite data from the 1970s to 2000s revealed a non-significant decrease in the forestlands of total Sundarbans by 1.1% which for the 6017 km2 BSMF is equivalent to 66 km2. In another report from around the same time, the estimated total forestland loss was approximately 127 km2. The Sundarbans has had great influence on local freshwater environments, facilitating profuse growth of Heritiera fomes (sundri), the tallest (at over 15 m) and most commercially important plant, but now has more polyhaline areas threatening the sundri, affecting growth and distribution of other mangroves and biota. Landsat images and GIS data from 1989 to 2010 at the extreme northern part of Khulna and Chandpai Ranges revealed the formation of a large number of small rivers and creeks some time before 2000 that reduce the 443 km2 forestland by 3.61%, approximately 16 km2, and decreasing H. fomes by 28.75% and total tree cover by over 3.0%. The number of the relatively low-priced plants Bruguiera sexangula, Excoecaria agallocha and Sonneratia apetala,has, on the other hand, increased. Similar degradation could be occurring in other ranges, thereby putting the survivability of the Bangladesh Sundarbans at risk. The growing stock of 296 plants per ha in 1959 had been reduced to 144 by 1996. Trend analysis using “Table Curve 2D Programme,” reveals a decreased number of 109 plants by the year 2020. The degradation of the Bangladesh Sundarbans has been attributed to reduced sediment-laden freshwater discharge through the BSMF river system since commissioning the Farakka Barrage on 21 April 1975 in India. To reduce salinity and forestland erosion, the maintenance of sediment-laden freshwater discharge through its river system has been suggested to re-create its pre-1975 environment for the growth of H. fomes, a true mangrove and the highest carbon-storing plant of the Sundarbans. This may possibly be achieved by proper sharing of the Ganges water from the Farakka Barrage, forming a consortium of India, Nepal, Bhutan and China, and converting parts or whole of the Ganges River into water reservoir(s). The idea is to implement the Ganges Barrage project about 33 km downstream, dredging sediments of the entire Gorai River and distributaries in the Ganges floodplain, thus allowing uniform sediment-laden freshwater flow to maintain an oligohaline environment for the healthy growth of mangroves. The system will also create healthy hinterlands of the Ganges floodplain with increased crop production and revenue. The expenditure may be met through carbon trading, as Bangladesh is a signatory of the Copenhagen Accord, UN Framework Convention on Climate Change. The total carbon reserve in the BSMF in 2010 was measured at about 56 million metric tons, valued at a minimum of US$ 280 million per year. The forest is rich in biodiversity, where over 65 species of mangroves and about 1136 wildlife species occur. The BSMF acts as a natural wall, saving property as well as millions of lives from natural disasters, the value of which is between 273 and 714 million US$. A 15 to 20 km band impact zone exists to the north and east of the BSMF, with a human settlement of about 3.5 million that is partly dependent on the forests. Three wildlife sanctuaries are to the south of the BSMF, the home of the great royal Bengal tigers, covering a total area of about 1397 km2. Construction of a coal-fired power plant at Rampal will be the largest threat to the Sundarbans. It is a reserve forest, declared as a Ramsar site of international importance and a UNESCO natural world heritage site.
Diversity2015, 7(3), 229-241; doi:10.3390/d7030229 - published 26 June 2015 Show/Hide Abstract
Abstract: Community saturation can help to explain why biological invasions fail. However, previous research has documented inconsistent relationships between failed invasions (i.e., an invasive species colonizes but goes extinct) and the number of species present in the invaded community. We use data from bird communities of the Hawaiian island of Oahu, which supports a community of 38 successfully established introduced birds and where 37 species were introduced but went extinct (failed invasions). We develop a modified approach to evaluate the effects of community saturation on invasion failure. Our method accounts (1) for the number of species present (NSP) when the species goes extinct rather than during its introduction; and (2) scaling patterns in bird body mass distributions that accounts for the hierarchical organization of ecosystems and the fact that interaction strength amongst species varies with scale. We found that when using NSP at the time of extinction, NSP was higher for failed introductions as compared to successful introductions, supporting the idea that increasing species richness and putative community saturation mediate invasion resistance. Accounting for scale-specific patterns in body size distributions further improved the relationship between NSP and introduction failure. Results show that a better understanding of invasion outcomes can be obtained when scale-specific community structure is accounted for in the analysis.