Advances in Ecology
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Open Access journal
ISSN (Print) 2356-6647 - ISSN (Online) 2314-761X
Published by Hindawi [333 journals]
[13 followers] Follow
Open Access journal
ISSN (Print) 2356-6647 - ISSN (Online) 2314-761X
Published by Hindawi [333 journals]
- Spatial Distribution of Elephants versus Human and Ecological Variables in
Abstract: An elephant survey was conducted in the Bia-Goaso Forest Block in western Ghana during the wet season month of November 2012 to determine the distribution of elephants and assess the human and ecological variables that affect them. One hundred and thirty 1-kilometre transects were systematically distributed in three strata (high, medium, and low density) based on elephant dung pile density recorded in an initial reconnaissance. Elephant activity was concentrated in southern and mid-Bia Conservation Area, the southern tip of Bia North Forest Reserve, and eastern Mpameso Forest Reserve towards the adjoining Bia Shelter belt, indicating a clumped distribution. Secondary forest, water availability, poaching activity, and proximity to roads and settlements explained a high proportion of variance in elephant distribution. Given that the Bia-Goaso Forest Block forms an important biogeographic corridor between Ghana and Cote d’Ivoire, more effort should be directed at mitigating the problems such as poaching activity, vehicular traffic, and impacts of settlements that hinder seasonal movements of forest elephants between western Ghana and eastern Cote d’Ivoire.
PubDate: Tue, 13 Dec 2016 12:20:46 +000
- Tree Species Composition and Regeneration Status of Shitalpur Forest Beat
under Chittagong North Forest Division, Bangladesh
Abstract: Biodiversity erosion particularly in developing countries is a matter of great concern to the global ecological community. Species composition and regeneration indicate the health of forest. This study explored tree species composition and regeneration of natural hill forest of Shitalpur under Chittagong North Forest Division through 27 sample plots of 20 m × 20 m for trees and 2 m × 2 m for regeneration. A total of 47 tree species belonging to 29 families and 17 regenerating species belonging to 15 families were recorded. The tree stem density, basal area, and wood volume were 0.49 m2/ha, 1425 stem/ha, and 189.9 m3/ha, respectively. Mean regeneration was significantly higher in bottom hill (14374 seedlings/ha) compared to top hill (9671 seedlings/ha). Toona ciliata was highest (4444 seedlings/ha) at the bottom hill compared to other hill positions. The result shows that only 36% of the tree species (17 out of 47) are regenerating in the study area, meaning majority of the tree species (64%) are not getting favorable conditions to regenerate. This might be due to absence of mature tree species as a result of overexploitation by local people. The findings may help in monitoring the species composition changes over time and adopting specific conservation programs for Shitalpur Forest.
PubDate: Thu, 03 Nov 2016 12:48:05 +000
- Estimation of Monetary Values of the Ecosystem Services Flow at the Tidal
Abstract: Most ecosystem services are regarded as free goods (i.e., priceless). This paper estimates monetary value of the ecosystem services after renaturalizing the navigation channel in the Kreetsand’s area along the tidal section of the Elbe River. The river channel is basically reconnected to its floodplain which is currently grassland. The paper used benefit transfer method whereby values from previous studies are adopted to estimate total economic value of the ecosystem services provided by the study area. The results show that total economic value of the ecosystem services flow at the Kreetsand’s shallow water area is 0.83 million/year. Nevertheless, the value seems to be underestimated due to errors inherited during valuation. After 44 years, the value will accumulate to 36.5 million, which is equal to the project investment cost estimated to be around 36.6 million. Based on the cost-benefit analysis results for the project, it is concluded that river renaturalization is the best option because it increases ecosystem services flow. The paper recommends that a similar study should be conducted to include more ecosystem services and ecosystem goods such as fish and water used for industrial purposes.
PubDate: Mon, 31 Oct 2016 08:26:39 +000
- Butterfly Species Diversity in Protected and Unprotected Habitat of Ise
Forest Reserve, Ise Ekiti, Ekiti State
Abstract: This study investigated butterfly diversity in the protected area (PA) and unprotected area (UPA) of Ise Forest reserve, Ise Ekiti, Ekiti State, using sweep net along existing trails. Butterfly species seen in the study sites were captured and released after proper identification was made. The results indicated that a total of 837 butterflies were identified in the study sites with 661 species observed in PA and 176 species in UPA. Butterfly species diversity was significantly different () between PA and UPA. Shannon diversity index was higher in PA (3.59) than UPA (3.27) as against Menhinick’s index, higher in UPA (2.11) than in PA (1.52). Likewise, 10 families of butterflies were recorded in PA and 8 families in UPA. The family with highest species occurrence was Satyridae (17.9%) in PA and Lycaenidae in UPA with 20.1%. Butterfly families’ diversity was not significant () between the two study sites. Ise Forest Reserve recorded approximately 6.6% of all butterflies recorded in West Africa. The findings indicated that mature secondary and regenerated forests supported high butterfly diversity and species richness, while cultivated land and grassland had a negative impact on butterfly community suggesting the negative effect of agricultural activities on the ecosystem.
PubDate: Sun, 09 Oct 2016 13:35:53 +000
- Tide Management in the Elbe River and Changes in Ecosystem Services
Abstract: Flood currents (tidal pumping) have led to the increase of transportation of sediments to the river’s upper estuary. In the tidal section of the Elbe River, more sediment is transported to the upper estuary with flood currents (tidal pumping) related to tidal asymmetry. This process contributes, amongst others, to dredging in order to obtain the water depth required for navigation safety. Cognizant of the above problems, construction of shallow water area is planned in order to reduce tidal asymmetry while improving ecological integrity at the tidal Elbe areas. The study on which this paper is based was conducted to assess ecological integrity and ecosystem services before and after the shallow water creation. Habitat identification and quality ranking were conducted for current habitat, while model habitats representing future state (after shallow water creation) were designed using HEC-RAS model simulation. The assessment matrix was used to assess ecological integrity and ecosystem services provisioning of the study area’s habitats before and after the shallow water creation, using potential indicators. Results indicate that there is increase in the ecological integrity after the project implementation. Based on the above explanation, it can be concluded that the measure will increase the flow of ecosystem services after its implementation.
PubDate: Wed, 03 Aug 2016 09:47:57 +000
- Carbon Sequestration in Tropical and Subtropical Plant Species in
Collaborative and Community Forests of Nepal
Abstract: Different plant species have different capacity of carbon sequestration but it is not assessed yet in Nepal. Therefore, this study was done to assess the species-wise carbon sequestration in two periods in forests. Three collaborative and three community forests were selected for the study. The selected forests were surveyed using GPS and mapped and stratified into tree, pole, and regeneration. Specifically 32, 33, and 31 samples were collected from Banke-Maraha, Tuteshwarnath, and Gadhanta-Bardibash collaborative forests, respectively, while 30, 25, and 22 samples were collected from Chureparwati, Buddha, and Chyandanda community forests correspondingly. The sample plots were of 25 m 20 m for tree strata. The diameter and height of plants were measured and samples were collected for three consecutive years. The estimated carbon stock of Shorea robusta was the highest 35.93 t ha−1 in 2011 which was slightly decreased to 34.43 t ha−1 in 2012 and reached 32.02 t ha−1 in 2013 in Banke-Maraha collaborative forest but it was the least 7.97, 8.92, and 10.29 t ha−1 in 2011, 2012, and 2013, respectively, in Chyandanda community forest. The highest carbon sequestration was recorded about 5.02 t ha−1 of Shorea robusta in Chyandanda community forest in between t2013 and t2012.
PubDate: Wed, 15 Jun 2016 12:12:02 +000
- Land-Cover Legacy Effects on Arbuscular Mycorrhizal Abundance in Human and
Wildlife Dominated Systems in Tropical Savanna
Abstract: Arbuscular mycorrhizal fungi (AMF) can be important mutualists to plant hosts in acquiring soil nutrients. Past work has not explored whether previous land-cover history influences current AMF abundance in croplands and whether different land-cover histories in grazed but not cultivated areas influence AMF. This study was conducted to assess the effects of land-cover history in and near Serengeti National Park on AMF abundance in areas with three different land uses. The results showed that land-cover history influenced a number of soil physicochemical properties following conversion of grassland to cropland or woodland to cropland during the past 27 years. Different original land cover generally did not significantly influence current AMF abundance in croplands or livestock-grazed soils. However, livestock-grazed current grasslands that were formerly woodlands had lower AMF abundance than sites that had been grasslands since 1984. These results suggest that lower AMF abundance in livestock-grazed and cropland areas as compared to protected wildlife-grazed areas may reflect reduced total carbon inputs and higher disturbance and are not strongly influenced by the legacy of previous land cover. Given that recent studies have detected legacy effects on AMF, such effects may reflect more the impact on the taxonomic composition of AMF rather than their total abundance.
PubDate: Wed, 24 Feb 2016 13:41:05 +000
- Antler and Body Size in Black-Tailed Deer: An Analysis of Cohort Effects
Abstract: For long-lived species, environmental factors experienced early in life can have lasting effects persisting into adulthood. Large herbivores can be susceptible to cohort-wide declines in fitness as a result of decreases in forage availability, because of extrinsic factors, including extreme climate or high population densities. To examine effects of cohort-specific extrinsic factors on size of adults, we performed a retrospective analysis on harvest data of 450 male black-tailed deer (Odocoileus hemionus columbianus) over 19 years in central California, USA. We determined that population density of females had a more dominant effect than did precipitation on body size of males. Harvest of female deer resulted in increases in the overall size of males, even though a 6-year drought occurred during that treatment period. Body size was most influenced by female population density early in life, while antler size was highly affected by both weather early in life and the year directly before harvest. This study provides insights that improve our understanding of the role of cohort effects in body and antler size by cervids; and, in particular, that reduction in female population density can have a profound effect on the body and antler size of male deer.
PubDate: Mon, 14 Dec 2015 07:12:39 +000
- The Potential Spread of Mycobacterium tuberculosis into the Environment in
the Creation of Spondylitis Tuberculosis Rabbit
Abstract: Direct Mycobacterium tuberculosis inoculation on rabbit vertebral body was used in rabbit spinal infection study. The potential spread of Mycobacterium tuberculosis into the environment will be observed in order to create the conditions fulfilling biosafety aspects. Two groups of six New Zealand rabbits were treatment group () and control group (). The treatment group had injection of 0.1 mL (107 cfu/mL) suspension of Mycobacterium tuberculosis into the vertebral body T12. They were incubated for 2 to 14 weeks. One rabbit per period of 2, 4, 6, and 14 weeks was euthanized to collect feces, urine, saliva, and tissue lesions. The control group had only feces, urine, and saliva to detect bacteria using AFB staining, culture, and PCR. Both two groups were kept in individual cages. They were put together in a large cage for 3 hours every day to interact with each other. AFB staining, culture, and radiological examination showed negative result, but in one rabbit, histopathological examination showed positive result and PCR examination in another rabbit of the treatment group. Spreading score was 1.05% and infected score was 0 (null). The procedure did not reveal the potential spread of Mycobacterium tuberculosis into the environment.
PubDate: Thu, 17 Sep 2015 13:47:11 +000
- Resource Selection by an Endangered Ungulate: A Test of Predator-Induced
Abstract: We investigated influences of risk of predation by mountain lions (Puma concolor), topographic metrics at multiple scales, and vegetation, land, and snow cover on resource selection by Sierra Nevada bighorn sheep (Ovis canadensis sierrae), an endangered taxon, during winters 2002–2007, in the Sierra Nevada, California, USA. We hypothesized that those mountain ungulates would trade off rewards accrued from using critical low-elevation habitat in winter for the safety of areas with reduced risk of predation. Sierra Nevada bighorn sheep did not trade off benefits of forage for reduced risk of predation but selected areas of high solar radiation, a correlate of vegetation productivity, where risk of predation by mountain lions was greatest, while mitigating indirect risk of predation by selecting for steep, rugged terrain. Bighorn sheep selected more strongly for areas where mountain lions were active, than for low-elevation habitat in winter, likely because mountain lions were most active in those areas of bighorn sheep winter ranges overlapping ranges of mule deer (Odocoileus hemionus), where both ungulates accrued forage benefits. We demonstrated reduced benefit of migration to low elevation during drought years, providing an alternative explanation to the predator-induced abandonment hypothesis for the disuse of low-elevation winter range observed during drought years.
PubDate: Wed, 18 Feb 2015 10:10:28 +000
- Size-Dependent Flowering in relation to Grazing in a Short-Lived
Abstract: In short-lived monocarpic perennials flowering probability depends on size and relative growth. Reproducing at a smaller size results in a higher prereproductive survival and shorter generation time but also may lead to lower fecundity. Conversely, reproducing at a larger size allows greater fecundity but leads to higher mortality during the prolonged vegetative period. Herbivory may influence the above described relationships via alterations in size at reproduction and survival. Here we use field data to explore in detail the reproduction of the short-lived monocarpic perennial C. vulgare under seasonal grazing. Vegetative plants were marked in paddocks with and without winter grazing, and their size, growth, and flowering status were recorded during a growing season in a field grazing experiment. Grazing increased both survival of vegetative plants and flowering probability, but it did not affect flowering size. The increase in flowering probability is a result of differential plant growth and size and may be related to greater resource availability, including light (necessary for flowering induction in C. vulgare) in grazed paddocks.
PubDate: Tue, 30 Dec 2014 07:51:38 +000
- Evidence against the Presence of Wolbachia in a Population of the Crayfish
Species Procambarus clarkii
Abstract: Wolbachia is a genus of intracellular alpha-Proteobacteria that is maternally inherited and is capable of inducing a variety of reproductive alterations in host species. The host range of Wolbachia is not determined completely but is known to contain a number of arthropod taxa, including crustaceans. Wolbachia has not been reported in crayfish, but sampling has been limited to date. We examine a species of crayfish, Procambarus clarkii, for Wolbachia infection using a suite of Wolbachia-specific primers in PCR assays. All specimens yielded negative results for Wolbachia infection and mathematical analysis of sample size shows a near 100% probability of detection for populations with greater than 0.1% infection rate.
PubDate: Mon, 22 Dec 2014 00:10:02 +000
- Effects of Mangrove Zonation and the Physicochemical Parameters of Soil on
the Distribution of Macrobenthic Fauna in Kadolkele Mangrove Forest, a
Tropical Mangrove Forest in Sri Lanka
Abstract: The ecology of the macrobenthic fauna of the mangrove forests has received little attention compared to the mangrove flora. The present study was aimed at filling this information gap and investigated if the diversity and distribution of macrobenthic fauna at Kadolkele mangrove forest, a pristine mangrove forest situated at the Negombo estuary in Sri Lanka, are governed by the mangrove zonation and variation of physicochemical parameters of the mangrove soil. Since the aerial photographs identified three distinct mangrove zones at Kadolkele, namely, Rhizophora, Avicennia, and Lumnitzera zones, fauna were sampled and physicochemical parameters of the soil were measured in belt transects that were established at each mangrove zone. Data were collected and analyzed using appropriate field sampling techniques and statistical methods, respectively. Results revealed that the physicochemical parameters in soil varied between the three mangrove zones and that the distribution of benthic fauna followed the mangrove zonation. Further, the diversity measures of epifauna were found to be higher than those of the infauna of this tropical estuary.
PubDate: Tue, 16 Dec 2014 10:03:36 +000
- Vehicle Collisions Cause Differential Age and Sex-Specific Mortality in
Abstract: As roads continue to be built and expanded, it is important that managers understand the effects that vehicle-related mortality can have on the population dynamics of wildlife. Our objective was to examine the frequency of mule deer (Odocoileus hemionus) vehicle collisions to determine if different demographic groups showed differential susceptibility to mortality when compared with their proportion in the population. We also compared vehicle collision rates of mule deer, elk (Cervus canadensis), and moose (Alces alces) to determine their relative vulnerability to vehicle collisions. We found that 65% of mule deer involved in vehicle collisions were female; of those, 40% were adult does ≥2 yrs. When we compared the proportion of bucks, does, and fawns killed in vehicle collisions to surveys of live deer, we found that bucks were killed at rate of 2.1–3.0 times their proportion in the population. Additionally, when we compared vehicle collision rates for 2010 and 2011, we found that mule deer were 7.4–8.7 times more likely to be involved in collisions than elk and 1.2–2.0 times more likely than moose. However, we were unable to detect a negative correlation () between mule deer abundance and increasing traffic volume.
PubDate: Tue, 11 Nov 2014 11:52:03 +000
- Sympatric Clupeoid Fish Larvae in the Northeastern Mediterranean:
Coexistence or Avoidance'
Abstract: The summer (July 2002 and 2003) larval concentrations of two commercially important clupeoid species (order: Clupeiformes), the European anchovy (Engraulis encrasicolus) and round sardinella (Sardinella aurita), were measured in Kavala Gulf (northern Aegean Sea), in order to examine their distribution patterns. Anchovy was generally most abundant, reaching 13 852 larvae 10 m−2 in 2003 and occurred in more stations compared to round sardinella. Despite the spawning of both species occurring across the entire gulf, the general spatial distribution of their larvae was different, with European anchovy larvae occupying the entire gulf and round sardinella larvae mainly concentrated at offshore stations. The reason proposed for the spatial segregation of their larvae is direct competition for resources. Yet, coexistence of the two species was observed in frontal areas with abundant food resources that prevent competition.
PubDate: Mon, 10 Nov 2014 06:54:33 +000
- Structuring Effects of Deer in Boreal Forest Ecosystems
Abstract: Many deer populations have recently increased worldwide leading to strong direct and indirect ecological and socioeconomical impacts on the composition, dynamic, and functions of forest ecosystems. Deer directly modify the composition and structure of vegetation communities, but they also indirectly affect other species of the ecosystem by modifying the structure of the vegetation. Here we review the results of a research program on overabundant white-tailed deer (Odocoileus virginianus) in the boreal forest of Anticosti Island (Québec, Canada) aimed at identifying deer densities compatible with forest regeneration. Various silvicultural systems and treatments failed to regenerate deer habitat at high deer densities, but planting size-adapted seedlings could be effective at moderate densities. Using a controlled deer density experiment, we found vegetation recovery at deer densities ≤ 15 deer/km2. The same experiment revealed that other groups of organisms such as insects and birds responded favorably to a reduction of deer density. We also found that alternative successional trajectories may occur after a certain period of heavy browsing during early succession. We conclude that one of the most important remaining research gaps is the need to identify habitat-specific threshold densities at which deer impacts occur and then to design effective wildlife and forest management strategies to limit deer impacts and sustain ecosystem integrity.
PubDate: Tue, 16 Sep 2014 08:34:06 +000
- Phosphate-Mediated Remediation of Metals and Radionuclides
Abstract: Worldwide industrialization activities create vast amounts of organic and inorganic waste streams that frequently result in significant soil and groundwater contamination. Metals and radionuclides are of particular concern due to their mobility and long-term persistence in aquatic and terrestrial environments. As the global population increases, the demand for safe, contaminant-free soil and groundwater will increase as will the need for effective and inexpensive remediation strategies. Remediation strategies that include physical and chemical methods (i.e., abiotic) or biological activities have been shown to impede the migration of radionuclide and metal contaminants within soil and groundwater. However, abiotic remediation methods are often too costly owing to the quantities and volumes of soils and/or groundwater requiring treatment. The in situ sequestration of metals and radionuclides mediated by biological activities associated with microbial phosphorus metabolism is a promising and less costly addition to our existing remediation methods. This review highlights the current strategies for abiotic and microbial phosphate-mediated techniques for uranium and metal remediation.
PubDate: Thu, 11 Sep 2014 13:18:45 +000
- Status of Biodiversity at Wetland Ecosystem of Mohangonj Upazila in
Abstract: Species in wetlands provide ecosystem services, and protect the sustainable environment for human beings. The wetland biodiversity has been impacted at Mohangonj in Bangladesh due to the development of major environmental threats. The present research is undertaken to report the species status, wetland properties, and major environmental pressures in each wetland ecosystem. Among the recorded species, the total percentage of visible, threatened, endangered, and extinct species was 69.23, 18.62, 10, and 1.92% in these wetland ecosystems, respectively. The highest number of threatened species was found in the wetland of Aizda (29%); the lowest was in Khalaura (8%). The maximum number of endangered species was noted in the wetland of Sonarthal (16%), and the minimum was in Chadra (4%) wetland. Four percent species were in the extinct category at some of the wetland ecosystems. Wetland biodiversity protects wetland ecosystem services and the sustainable environment for species conservation. Continuous monitoring of wetland biodiversity might be helpful for the conservation of species in the wetland ecosystem.
PubDate: Tue, 02 Sep 2014 06:28:06 +000
- Microevolutionary Effects of Habitat Fragmentation on Plant-Animal
Abstract: Plant-animal interactions are a key component for biodiversity maintenance, but they are currently threatened by human activities. Habitat fragmentation might alter ecological interactions due to demographic changes, spatial discontinuities, and edge effects. Also, there are less evident effects of habitat fragmentation that potentially alter selective forces and compromise the fitness of the interacting species. Changes in the mutualistic and antagonistic interactions in fragmented habitats could significantly influence the plant reproductive output and the fauna assemblage associated with. Fragmented habitats may trigger contemporary evolution processes and open new evolutionary opportunities. Interacting parties with a diffuse and asymmetric relationship are less susceptible to local extinction but more prone to evolve towards new interactions or autonomy. However, highly specialized mutualisms are likely to disappear. On the other hand, ecological interactions may mutually modulate their response in fragmented habitats, especially when antagonistic interactions disrupt mutualistic ones. Ecoevolutionary issues of habitat fragmentation have been little explored, but the empiric evidence available suggests that the complex modification of ecological interactions in fragmented habitats might lead to nonanalogous communities on the long term.
PubDate: Mon, 25 Aug 2014 10:54:50 +000
- Saltcedar (Tamarix ramosissima) Invasion Alters Decomposer Fauna and Plant
Litter Decomposition in a Temperate Xerophytic Deciduous Forest
Abstract: Plant invasions may alter the soil system by changing litter quality and quantity, thereby affecting soil community and ecosystem processes. We investigated the effect of Tamarix ramosissima invasion on the decomposer fauna and litter decomposition process, as well as the importance of litter quality in decomposition. Litter decomposition and decomposer communities were evaluated in two monospecific saltcedar forests and two native forests in Argentina, in litterbags containing either local litter (saltcedar or dominant native species) or a control litter. Saltcedar invasion produced an increase in Collembola, Acari, and total mesofauna abundance, regardless of the litter type. Control litter decomposition was higher in the native forest than in the saltcedar forest, showing that increased abundance of decomposer fauna does not necessarily accelerate decomposition processes. Local litter decomposition was not different between forests, suggesting that decomposer fauna of both ecosystems is adapted to efficiently decompose the autochthonous litter. Our results suggest that the introduction of a resource with higher quality than the local one has a negative effect on decomposition in both ecosystems, which is more pronounced in the invaded forest than in the native forest. This finding stresses the low plasticity of saltcedar decomposer community to adapt to short-term environmental changes.
PubDate: Thu, 21 Aug 2014 05:32:43 +000
- Community Structure and Distribution Pattern of Intertidal Invertebrate
Macrofauna at Some Anthropogenically Influenced Coasts of Kathiawar
Abstract: Present communication reports the community structure and distribution pattern of intertidal invertebrate macrofauna at four shores of the Kathiawar peninsular coastline off the Arabian Sea (India). The selected shores have different levels of human activities. Present report tests three hypotheses; that is, (i) distribution of invertebrate macrofauna in these shores is influenced by space and time, (ii) abiotic factors have a profound influence on the distribution pattern of intertidal macrofaunal assemblages, and (iii) human activities influence the community structure of the intertidal invertebrate macrofauna at these shores. To test these hypotheses, spatiotemporal variations in different ecological indices were studied. A total of 60 species from six phyla were considered for the study. High species diversity was recorded during winter and monsoon seasons in almost all the shores studied. It was also evident that a few environmental factors had a cumulative influence on the distribution pattern of intertidal macrofauna. Significant spatial variations in the species diversity and evenness were also observed. Though the shores studied have similar coast characteristics and climatic conditions, they face different levels of human activities. Therefore, the observed variations in the intertidal faunal assemblage were possibly caused by anthropogenic stress.
PubDate: Wed, 06 Aug 2014 00:00:00 +000
- Ecological Speciation and the Intertidal Snail Littorina saxatilis
Abstract: In recent decades biologists studying speciation have come to consider that the process does not necessarily require the presence of a geographical barrier. Rather, it now seems to be possible for reproductive barriers to evolve within what was hitherto a single ‘‘species.’’ The intertidal snail Littorina saxatilis has been the focus of a considerable amount of work in this context, and it is now thought of as a good case study of ‘‘ecological speciation.’’ We review some of this work and briefly consider prospects for future developments.
PubDate: Tue, 22 Jul 2014 07:29:46 +000
- Experiments Are Revealing a Foundation Species: A Case Study of Eastern
Hemlock (Tsuga canadensis)
Abstract: Foundation species are species that create and define particular ecosystems; control in large measure the distribution and abundance of associated flora and fauna; and modulate core ecosystem processes, such as energy flux and biogeochemical cycles. However, whether a particular species plays a foundational role in a system is not simply asserted. Rather, it is a hypothesis to be tested, and such tests are best done with large-scale, long-term manipulative experiments. The utility of such experiments is illustrated through a review of the Harvard Forest Hemlock Removal Experiment (HF-HeRE), a multidecadal, multihectare experiment designed to test the foundational role of eastern hemlock, Tsuga canadensis, in eastern North American forests. Experimental removal of T. canadensis has revealed that after 10 years, this species has pronounced, long-term effects on associated flora and fauna, but shorter-term effects on energy flux and nutrient cycles. We hypothesize that on century-long scales, slower changes in soil microbial associates will further alter ecosystem processes in T. canadensis stands. HF-HeRE may indeed continue for >100 years, but at such time scales, episodic disturbances and changes in regional climate and land cover can be expected to interact in novel ways with these forests and their foundation species.
PubDate: Thu, 17 Jul 2014 07:51:02 +000
- Distribution and Diversity of Oligochaetes in Selected Ponds of
Thiruvananthapuram District, Kerala, South India
Abstract: The present study was carried out to evaluate the distribution and diversity of oligochaete fauna in selected ponds of Thiruvananthapuram district in Kerala, South India. The sediment samples were collected from three ponds seasonally during the period December 2006 to November 2008. In the study, 10 oligochaete species which belong to 8 genera were identified in three selected ponds. These include Dero digitata, Dero nivea, Dero obtusa, Pristina longiseta, Aulophorus furcatus, Stylaria fossularis, Chaetogaster spp., Aeolosoma spp., Tubifex tubifex and Limnodrilus hoffmeisteri. Tubifex tubifex and Limnodrilus hoffmeisteri are the pollution-indicator oligochaete species identified in the fresh water ponds, which reveals that the studied ponds are subjected to pollution.
PubDate: Thu, 17 Jul 2014 07:44:18 +000
- Leopard Panthera pardus fusca Density in the Seasonally Dry, Subtropical
Forest in the Bhabhar of Terai Arc, Nepal
Abstract: We estimated leopard (Panthera pardus fusca) abundance and density in the Bhabhar physiographic region in Parsa Wildlife Reserve, Nepal. The camera trap grid, covering sampling area of 289 km2 with 88 locations, accumulated 1,342 trap nights in 64 days in the winter season of 2008-2009 and photographed 19 individual leopards. Using models incorporating heterogeneity, we estimated 28 (±SE 6.07) and 29.58 (±SE 10.44) leopards in Programs CAPTURE and MARK. Density estimates via 1/2 MMDM methods were 5.61 (±SE 1.30) and 5.93 (±SE 2.15) leopards per 100 km2 using abundance estimates from CAPTURE and MARK, respectively. Spatially explicit capture recapture (SECR) models resulted in lower density estimates, 3.78 (±SE 0.85) and 3.48 (±SE 0.83) leopards per 100 km2, in likelihood based program DENSITY and Bayesian based program SPACECAP, respectively. The 1/2 MMDM methods have been known to provide much higher density estimates than SECR modelling techniques. However, our SECR models resulted in high leopard density comparable to areas considered better habitat in Nepal indicating a potentially dense population compared to other sites. We provide the first density estimates for leopards in the Bhabhar and a baseline for long term population monitoring of leopards in Parsa Wildlife Reserve and across the Terai Arc.
PubDate: Wed, 16 Jul 2014 15:57:57 +000
- Occurrence of Malabar Snakehead, Channa diplogramma (Perciformes:
Channidae) from River Valapattanam, Western Ghats of Kerala, India
Abstract: We report the occurrence of Channa diplogramma in the Valapattanam River in March 2013 and this study adds to the species record of C. diplogramma in terms of diversity and range distribution in the River Valapattanam and South India.
PubDate: Tue, 08 Jul 2014 11:53:58 +000
- Harvesting as an Alternative to Burning for Managing Spinifex Grasslands
Abstract: Sustainable harvesting of grasslands can buffer large scale wildfires and the harvested biomass can be used for various products. Spinifex (Triodia spp.) grasslands cover ≈30% of the Australian continent and form the dominant vegetation in the driest regions. Harvesting near settlements is being considered as a means to reduce the occurrence and intensity of wildfires and to source biomaterials for sustainable desert living. However, it is unknown if harvesting spinifex grasslands can be done sustainably without loss of biodiversity and ecosystem function. We examined the trajectory of plant regeneration of burned and harvested spinifex grassland, floristic diversity, nutrient concentrations in soil and plants, and seed germination in controlled ex situ conditions. After two to three years of burning or harvesting in dry or wet seasons, species richness, diversity, and concentrations of most nutrients in soil and leaves of regenerating spinifex plants were overall similar in burned and harvested plots. Germination tests showed that 20% of species require fire-related cues to trigger germination, indicating that fire is essential for the regeneration of some species. Further experimentation should evaluate these findings and explore if harvesting and intervention, such as sowing of fire-cued seeds, allow sustainable, localised harvesting of spinifex grasslands.
PubDate: Sun, 06 Jul 2014 06:29:16 +000
- Effects of Climate Change and Various Grassland Management Practices on
Grasshopper (Orthoptera) Assemblages
Abstract: Influence of different grassland management practices on Orthoptera assemblages inhabiting humid grassland areas was studied since 2003 to 2011. The examined sites were within the protected area of Balaton Uplands National Park. The physiognomy and climatic conditions of the studied habitats were similar but their land use types were significantly different. After the preliminary analyses of Nonmetric multidimensional scaling, neighbour joining clustering, and Spearman rank correlation, we examined the possible effects of such independent variables as land use (nonmanagement, mowing, grazing), microclimate (humidity and temperature), regional macroclimate (annual and monthly mean temperatures and rainfall), using General Linear Mixed Models, and canonical correlation analysis. Our results showed that the effect of grassland management practices on the organization of Orthoptera assemblages was at least as important as that of macro- and microclimate. Furthermore, grassland management could intensify the influence of several local and regional parameters. These results can help finding the most suitable type of grassland management to conserve the grasshopper assemblages.
PubDate: Wed, 02 Jul 2014 09:11:28 +000
- Living at the Limits: Evidence for Microbial Eukaryotes Thriving under
Pressure in Deep Anoxic, Hypersaline Habitats
Abstract: The advent of molecular tools in microbial ecology paved the way to exploit the diversity of microbes in extreme environments. Here, we review these tools as applied in one of the most polyextreme habitats known on our planet, namely, deep hypersaline anoxic basins (DHABs), located at ca. 3000–3500 m depth in the Eastern Mediterranean Sea. Molecular gene signatures amplified from environmental DHAB samples identified a high degree of genetic novelty, as well as distinct communities in the DHABs. Canonical correspondence analyses provided strong evidence that salinity, ion composition, and anoxia were the strongest selection factors shaping protistan community structures, largely preventing cross-colonization among the individual basins. Thus, each investigated basin represents a unique habitat (“isolated islands of evolution”), making DHABs ideal model sites to test evolutionary hypotheses. Fluorescence in situ hybridization assays using specifically designed probes revealed that the obtained genetic signatures indeed originated from indigenous polyextremophiles. Electron microscopy imaging revealed unknown ciliates densely covered with prokaryote ectosymbionts, which may enable adaptations of eukaryotes to DHAB conditions. The research reviewed here significantly advanced our knowledge on polyextremophile eukaryotes, which are excellent models for a number of biological research areas, including ecology, diversity, biotechnology, evolutionary research, physiology, and astrobiology.
PubDate: Thu, 08 May 2014 13:08:06 +000