Secondary succession of woody plants following sand mining in the Soesdyke-Linden area, Guyana: A Chronosequence study

Sandy soils comprise a large proportion of low productivity areas of Guyana on the Soesdyke-Linden Highway, where there is ecological disturbance and evidence of secondary succession after sand mining activities. This study investigated secondary succession of woody plants on abandoned sand mining locations. Secondary succession was studied inferentially by comparing sites in a homogeneous zone that was abandoned at different times post disturbance due to sand mining. Species diversity and community composition at five (5) sites which included an undisturbed area and areas at 3, 5, 10, and 15 years after the disturbance of sand mining were studied. Fifteen 10m x 10m plots were sampled for woody plants with a DBH of more than 2.5cm, and 1m x 1m sub-plots were randomly selected and sampled for seedlings with a DBH less than 2.5cm. A total of 241 plants were recorded, encompassing 22 species across 16 Families. Tapiria marchandii of the family Anacardiaceae dominated the chronosequences of 5, 10, and 15 years and recorded the highest Importance Value Index (IVI) of 112.88, 154.51, and 215.42, respectively. Dimorphandra conjugata of the family Fabaceae also adapted well to conditions post sand mining in the latter chronosequences of 10 and 15 years with IVIs of 54.17 and 38.83, respectively. The youngest site of three years exhibited the highest species diversity post the disturbance of sand mining; however, the undisturbed site possessed the highest overall species diversity. Species diversity of chronosequences decreased with age as competition for limited resources increased and the dominant species proliferated.

Assessment and Valuation of Commercially Important Bivalves and Gastropods within the Seagrass Beds of Laguindingan, Misamis Oriental and Rizal, Zamboanga del Norte, Philippines

A study was conducted to assess the abundance and value of commercially important bivalves and gastropods within the seagrass beds of Laguindingan, Misamis Oriental and Rizal, Zamboanga del Norte, Mindanao, Philippines. The line transect method was used to assess the diversity of the bivalves and gastropods within the seagrass beds and coring was used in collecting sediment samples. Laguindingan was categorized as undisturbed site, while Rizal as disturbed site. The results identified three families of gastropods in undisturbed and thirteen families in disturbed, comprising a total of seven bivalves and six gastropods. Cyprea sp. Dominated in undisturbed area, while Anadara inequivalves dominated in disturbed area. The diversity index in disturbed (1.57) was greater than in undisturbed (0.88) probably due to high organic matter (2.56ppm) compared to the undisturbed area (1.92ppm). Ironically, the total volume of bivalves and gastropods production in disturbed area was higher at19.84 kg compared with2.23 kg in undisturbed. In terms of total monetary value, the undisturbed production could yield PHP 22,672.32 (USD 466.48) in an approximated area of 165 ha, while PHP 422,130.50 (USD 8,685.37) in 326 ha in the disturbed area. The study revealed that higher diversity resulted in higher production with greater monetary value derived from bivalves and gastropods in disturbed area contributed by higher organic load. Protection and management of the seagrass beds is likely most needed in both disturbed and undisturbed are as to support not only a robust but also a healthy production of shellfish fit for human consumption.

Experimental and Numerical Analyses of the Thermal Regime of a Traditional Embankment in Permafrost Regions

Traditional embankment is widely used in the permafrost regions along the Qinghai-Tibet Railway (QTR) because of its simple construction and lower cost. However, this form of embankment has insufficient ability to resist external thermal disturbance. To clarify the thermal characteristics of traditional embankment under climate warming, the ground temperature change process of section K1068 + 750 of the QTR was analysed in this study. Based on the field monitoring data from 2006 to 2019 and the established heat transfer model, the past and future changes of permafrost thermal regime under the embankment were analysed. The results show that the degradation of permafrost under the embankment is faster than that under the undisturbed site due to the combined of embankment construction and climate warming. The sunny-shady slope effect related to embankment orientation makes the distribution of permafrost temperature under embankment asymmetric. In the long term, permafrost degrades both under the undisturbed site and embankment. The continuous degradation of permafrost causes the settlement and deformation of embankment, especially the asymmetric degradation of permafrost on sunny side and shady side will cause longitudinal cracks on the embankment. Therefore, timely application of strengthening measures which can slow down the degradation of permafrost and adjust the uneven ground temperature on the sunny and shady sides under the embankment is of great significance to the safety of the traditional embankment.

Contrary to vertebrates, less aggressive and more consistent individuals are common in disturbed habitats in the colonial spider Metabus gravidus (Araneae: Araneidae)

Habitat disturbance may affect average behavioural types and consistency/plasticity of behaviour. Studies with solitary vertebrates suggest that human-modified habitats may favour bolder, more aggressive and more plastic individuals. We evaluated whether wild colonial spiders, Metabus gravidus, vary in the magnitude, consistency and plasticity of boldness and aggressiveness between an undisturbed forest and an adjacent urban area in Monteverde, Costa Rica. Repeatability of aggressiveness was high at the disturbed site but moderate at the undisturbed site; repeatability of boldness was low at both sites. Individual and population plasticity was similar between sites for both behaviours. Aggressiveness decreases with increasing colony size at the disturbed site; this trend was not observed at the undisturbed site. Boldness did not change with colony size. In contrast to solitary animals, our results indicate that less aggressive and more consistent colonies may have an advantage living in human-disturbed habitats.

Control of downy brome (Bromus tectorum) and Japanese brome (Bromus japonicus) using glyphosate and four graminicides: effects of herbicide rate, plant size, species, and accession

Nonnative annual brome invasion is a major problem in many ecosystems throughout the semiarid Intermountain West, decreasing production and biodiversity. Herbicides are the most widely used control technique but can have negative effects on co-occurring species. Graminicides, or grass-specific herbicides, may be able to control annual bromes without harming forbs and shrubs in restoration settings, but limited studies have addressed this potential. This study focused on evaluating the efficacy of glyphosate and four graminicides to control annual bromes, specifically downy brome and Japanese brome. In a greenhouse, glyphosate and four graminicides (clethodim, sethoxydim, fluazifop-P-butyl, and quizalofop-P-ethyl) were applied at two rates to downy brome plants of different heights (Experiment 1) and to three accessions of downy brome and Japanese brome of one height (Experiment 2). All herbicides reduced downy brome biomass, with most effective control on plants of less than 11 cm and with less than 12 leaves. Overall, quizalofop-P-ethyl and fluazifop-P-butyl treatments were most effective, and glyphosate and sethoxydim treatments least effective. Accessions demonstrated variable response to herbicides: the downy brome accession from the undisturbed site was more susceptible to herbicides than downy brome from the disturbed accession and Japanese brome accessions. These results demonstrate the potential for graminicides to target these annual bromes in ecosystems where they are growing intermixed with desired forbs and shrubs.

The effect of mangrove restoration on avian assemblages of a coastal lagoon in southern Mexico

Background Mangrove forests provide many ecosystem services, including the provision of habitat that supports avian biodiversity. However, hurricanes can knock down trees, alter hydrologic connectivity, and affect avian habitat. In 1995, Hurricanes Opal and Roxanne destroyed approximately 1,700 ha of mangrove forest in Laguna de Términos, Mexico. Since then, hydrological restoration has been implemented to protect the mangrove forest and its biodiversity. Methods Since avian communities are often considered biological indicators of ecosystem quality, avian diversity and species relative abundance were evaluated as indicators of mangrove restoration success by comparing undisturbed mangrove patches with those affected by the hurricanes. Using bird surveys, similarity analyses, and generalized linear models, we evaluated the effects of water quality variables and forest structure on the relative abundance and diversity of the avian community in disturbed, restored, and undisturbed mangrove patches. Results Higher bird species richness and relative abundances were found in disturbed and restored sites compared to the undisturbed site. After restoration, values of frequency of flooding, water temperature, tree density, and the number of tree species were more similar to that of the undisturbed site than to the values of the disturbed one. Such variables influenced the relative abundance of bird guilds in the different habitat conditions. Furthermore, some insectivorous bird species, such as the Yellow Warbler and Tropical Kingbird, were found to be similarly abundant in both undisturbed and restored sites, but absent or very low in occurrence at the disturbed site. Conclusions Collectively, our results strongly suggest that hydrologic restoration helps to enhance niche availability for different bird guilds, including water and canopy bird species. Our work can help inform management strategies that benefit avian communities in mangrove forests and wetland systems.

Arbuscular mycorrhizal fungi in Melocanna baccifera from disturbed and undisturbed sites in Mizoram, India

Melocanna baccifera is a well-known native bamboo species of India belonging to the grass family Poaceae. A study on the presence of arbuscular mycorrhizal fungi (AMF) association with M. baccifera was conducted from a disturbed and undisturbed bamboo forest sites within Mizoram University, Mizoram, India. Soil from the rhizosphere region as well as physico-chemical properties of the soil were taken to study AMF diversity. The roots were observed for percentage colonization by AMF. It was found that undisturbed site had higher colonization percentage (56%) than the disturbed site (46%). The Shannon’s diversity index showed that undisturbed site (1.46) had more diversity than the disturbed site (1.59) while disturbed site showed lower index of dominance (3.34) which indicates higher shared dominance of AMF species than undisturbed site (4.66).

Prevalence, Genotype Richness, and Coinfection Patterns of Hemotropic Mycoplasmas in Raccoons (Procyon lotor) on Environmentally Protected and Urbanized Barrier Islands

ABSTRACT Raccoons (Procyon lotor) are successful urban adapters and hosts to a number of zoonotic and nonzoonotic pathogens, yet little is known about their hemoplasma infections and how prevalence varies across habitat types. This study identifies hemotropic Mycoplasma species infection in raccoons from urban and undisturbed habitats and compares hemoplasma infection in sympatric urban cats (Felis catus) from the same geographic region. We collected blood from raccoons (n = 95) on an urban coastal island (n = 37) and an undisturbed coastal island (n = 58) and from sympatric urban cats (n = 39) in Georgia, USA. Based on 16S rRNA gene amplification, 62.1% (59/95) of raccoons and 17.9% (7/39) of feral cats were positive for hemoplasma. There was a greater percentage of hemoplasma-infected raccoons on the undisturbed island (79.3% [46/58]) than on the urban island (35.1% [13/37]; χ2 = 16.9, df = 1, P = 0.00004). Sequencing of the full-length 16S rRNA gene amplicons revealed six hemoplasma genotypes in raccoons, including five novel genotypes that were distinct from three known hemoplasma species identified in the sympatric cats. In addition, the hemoplasma genotypes detected in raccoons were not identified in sympatric cats or vice versa. Although all six hemoplasma genotypes were found in raccoons from urban and undisturbed islands, coinfection patterns differed between sites and among individuals, with the proportion of coinfected raccoons being greater in the undisturbed site. This study shows that raccoons are hosts for several novel hemoplasmas and that habitat type influences infection patterns. IMPORTANCE This study provides information about novel hemoplasmas identified in raccoons (Procyon lotor), which can be used for assessments of the prevalence of these hemoplasmas in raccoon populations and for future studies on the potential pathogenic impacts of these hemoplasmas on raccoon health. Raccoons from the undisturbed habitat had a higher prevalence of hemoplasma infection than urban raccoons. There does not appear to be cross-species transmission of hemotropic mycoplasmas between urban raccoons and feral cats. Raccoons appear to be hosts for several novel hemoplasmas, and habitat type influences infection patterns.

Phytosocialogical and Ethnomedicinal Studies of Sacred Groves in Konjikuppam Village, Cuddalore District, Tamil Nadu

The konjikuppam village lies on the state highway linking panruti (5 km south) and Neyveli (10 km north). The sacred grove of konjikuppam is also situated on the main read and is proximate to the village. A large bond of about 3 ha. Size lies behind the temple complex and cannel bringing strong water from the neighboring shallow ferralitic terrain runs into it. An extensive floristic survey of carried out in the sacred groves at monthly intervals between December 2011 and October 2012. Specimen flowering plants were collected and identified taxonomically with the help of different floras. Nine plots were established in three different disturbance areas within the sacred groves and it is divided into three site I. Disturbances, II. Moderately disturbance III. Undisturbance. Present study revealed that a total number of 110 plants belonging to 96 genera and 45 families were recorded from three sites (I. Disturbed, II. Moderately Disturbed, III. Undisturbed) of konjikuppam sacred groves Cuddalore district. The present study revealed that more number of species found in undisturbed site III and least number and density in disturbed site I. a total of 24 plants used in herbal preparations. The local health traditions provide immediate and cheaper remedy or relief to the poor and down trodden inhabiting the villages. The devastation of species diversity in the study area there is an urgent need for regeneration of the species for conservation of species and biodiversity.