A Comparative Diversity Analysis of Soil Nematodes of Rajouri, Jammu and Kashmir, India

Diversity of Nematode communities in Pir Panjal range of Jammu and Kashmir along with nematodes’ driven indices were studied. Himalayan mountainous areas of district Rajouri were selected. Community composition and trophic structure (feeding types) were assessed and were analyzed at various altitudes and across varied habitats, which differ significantly on moving from low elevation to high elevation areas. A total of 47 genera were recorded across mountain clines. In terms of taxonomic groups, in higher elevations, the order Dorylaimids represent 55.18%, followed by Tylenchida 28.85%, Mononchida 2.38%, Rhabditida 2.18%, and Aphelenchida 2.05%, whereas in the lower reaches, the order Rhabditida represent 30.18%, followed by Dorylaimids 28.75%, Tylenchida 15.85%, Mononchida 10.05% and Aphelenchida 1.05%. In terms of trophic groups, in the upper reaches, omnivores (56.6%) predominate, representing highest number, followed by plant parasitic (33.4%), bacterivore (4.2%), predatory (3.2%) and fungivore (2.60%). In the lower reaches, Bacterivores (38.08%) predominates, followed by omnivores (29.85%), plant parasitic (18.5%), predatory (12.5%) and fungivores (1.07%). The total nematode abundance and diversity were found increasing with elevation This pattern applied to most genera and feeding types. Across the regions, nematode diversity and community composition increases positively with elevations and richer habitats as given by Simpson index and Shannon-Weaver index. We conclude that nematode assemblages are potentially good bioindicators of climate change. They reacted sensitively and predictably to the changing environment. Thus, nematodes have suitability for long-term monitoring of biodiversity and community changes. Sampling techniques are well standardized and inexpensive. Furthermore, feeding types of nematodes can be determined with minimal taxonomic skills.

Assessment of benthic environmental disturbance in the Ba Lai estuary using the nematode biomass spectra

The researchs on the biomass spectra - a functional characteristic of biotic communities is still limited. In this study, the nematode biomass spectra in the bottom of Ba Lai estuary was investigated at six subtidal stations from the sea toward the upstream. The result showed that nematode biomass spectra ranged between -8 and 1 being significantly different between stations, and the lowest biomass of those spectras was in station BL4 (< 2 µg) which is upwardly closed to the Ba Lai dam. BL4 was also characterized by the lowest nematode abundance in the studied area. In addition, station BL3 downwardly closed to the dam exhibited low number of individuals. The heterogeneity in the nematode biomass spectra of BL3 and BL4 might due to the disturbance in the sedimentary environment of Ba Lai estuary related to the dam impact. This research again supports the important role of biomass spectra as bioindicator tool for biomonitoring and environmental quality assessment. Therefore, applying nematode biomass spectra is recommended for environmental assessment due to their advantages such as timesaving, not taxonomical expertise-requirement.

Altitudinal gradient affect abundance, diversity and metabolic footprint of soil nematodes in Banihal-Pass of Pir-Panjal mountain range

Despite enormous diversity, abundance and their role in ecosystem processes, little is known about how community structures of soil-inhabiting nematodes differ across elevation gradient. For this, soil nematode communities were investigated along an elevation gradient of 1000–2500 masl across a temperate vegetation in Banihal-Pass of Pir-Panjal mountain range. We aimed to determine how the elevation gradient affect the nematode community structure, diversity and contribution to belowground carbon assimilation in the form of metabolic footprint. Our results showed that total nematode abundance and the abundance of different trophic groups (fungivores, herbivores and omnivores) declined with the increase of elevation. Shannon index, generic richness and evenness index indicated that nematode communities were more diverse at lower elevations and declined significantly with increase in elevation. Nematode community showed a pattern of decline in overall metabolic footprint with the increase of elevation. Nematode abundance and diversity proved to be more sensitive to elevation induced changes as more abundant and diverse nematode assemblage are supported at lower elevations. Overall it appears nematode abundance, diversity and contribution to belowground carbon cycling is stronger at lower elevations and gradually keep declining towards higher elevations under temperate vegetation cover in Banihal-pass of Pir-Panjal mountain range.

Oil Pollution Effects on Nematodes in Mangrove Sediment: A Microcosm Study

The effects of oil pollution on meiobenthic nematode assemblages in a mangrove sediment were investigated. Microcosms comprised 350 ml plastic jars that were filled with 200 g mangrove sediment and subjected to oiling, with or without addition of fertiliser. In the oiled treatments, 15 ml of Bunker fuel oil 180 and 5 ml/L fertiliser (N: P: K: 3: 2: 5) were added to the soil. After four weeks, nematodes were extracted and identified. In the unfertilised oiled treatment, nematode abundance and species richness were significantly reduced by 87% and 53%, respectively, compared to the control. In the fertilised oiled treatment, nematode abundance and species richness increased by 56% and 30% respectively. The eight taxa present in the control but absent in the oiled treatments (Monhystera, Prodesmodora, Plectus, Rhabditis, Koerneria, Rotylenchus, Tobrilus, and Fictor) were characterised as oil-intolerant. The seven taxa present in the oiled treatments (Monhystera, Ethmolaimus, Panagrolaimus, Camacolaimus, Hemicycliophora typica, and H. ripa and a species of the family Xyalidae) were characterised as oil-tolerant and resilient. In all treatments, the dominant species was Ethmolaimus. Taxa such as Rhabditis, Koerneria and Rotylenchus survived oiling, due to the addition of fertiliser. Fertilizer amendment favoured survival of Rhabditis, Koerneria and Rotylenchus and increased reproduction in Camacolaimus.

Nature Restoration Shifts the Abundance and Structure of Soil Nematode Communities in Subtropical China

Aims Soil nematode community is an important component of the soil food web, which has been widely recognized as a key bio-indicator for assessing the influence of nature restoration on ecological functions. However, the dynamics of the abundance, diversity and function of soil nematode community remain unclear under different forest succession phases. Methods The soil nematode community of natural secondary forests was investigated using a chronosequence approach. Nature restoration for five succession stages were sampled in this study to represent a wide range of stand age groups.Results Soil nematode abundance gradually increased with forest stand age, which reached a peak value (574 individuals 100 g-1 dry soil) in the older age classes. In contrast, soil nematode diversity was not affected by forest stand age. Soil available nitrogen and phosphorus were key factors influencing soil nematode abundance and diversity during forest secondary succession. The plant parasite index decreased with forest stand age, which indicated that ecosystem function and health would be improved as nature restoration progresses. In addition, the structure of soil nematode community was more sensitive to forest secondary succession compared to plant community and soil microbial community. The bottom-up effects of the plant and microbial communities on soil nematode community were important drivers of nematode community structure in subtropical forests. Conclusions Overall, this study demonstrates the active responses of soil nematode community to nature restoration, and highlights the importance of the above-ground and below-ground interactions to the soil food web.

Short Communication: Nematodes associated with Robusta coffee plantations in Malang District, East Java, Indonesia

Tarno H, Marsudi EW, Widjayanti T, Setiawan Y. 2021. Short Communication: Nematodes associated with Robusta coffee plantations in Malang District, East Java, Indonesia. Biodiversitas 22: 3306-3312. Coffee (Coffea spp.) is an important commodity in Indonesia. Nematodes have different roles, such as plant parasites and non-parasites, and are commonly found in the soil of coffee plantations. This research determined the ecological role, diversity, and abundance of nematodes in three coffee plantations in Malang District, East Java. We used a Whitehead tray to extract and isolate nematodes from the soil and root samples. Nematodes were identified based on their morphological characteristics. Analysis of variance and diversity indices were used to identify the differences among three coffee plantations. We identified eight nematode genera in the Ngantang sub-district site. In the Jatikerto Agrotechnopark and University of Brawijaya Forest sites, six genera were identified. Criconemoides, Pratylenchus, Xiphinema, Helicotylenchus are plant-parasitic nematodes, and Mononchus, Dorylaimus, Rhabditis, and Aphanolaimus are non-plant parasitic nematodes. Non-plant parasitic nematodes were more abundant than plant-parasitic nematodes in all sites. Non-plant parasitic nematode, Dorylaimus was the dominant genus in this study (272 individuals), ca. 35% of the total nematodes collected. In this study, the differences between coffee plantations and soil pH influence nematode abundance. The nematode abundance increases when the soil pH is lower.

Soil Nematode Communities in Managed and Natural Temperate Forest

Forest management and the stand age play key roles in determining the composition of soil biota, including nematodes. We analysed the effect of the interaction between stands of natural forest and stands influenced by human activity on nematode communities, necessary for realistically assessing the specific potentials of forest soils, plant protection, forest management, and land use management. Nematode communities were evaluated and compared in managed beech and spruce forests in three age classes (0–20, 40–60, and 100–120 years old) and an unmanaged old-growth temperate forest. A total of 51 nematode genera were found in the forests. The number of nematode genera was the highest (46) in European beech forests, dominated by Rhabditis and Filenchus. In contrast, the number of nematode genera was the lowest (37) in a Norway spruce forest, but where nematode abundance was the highest due mostly to the high abundance of bacterivorous nematodes such as Acrobeloides, Plectus, and Rhabditis. The unmanaged old-growth forest had the lowest nematode abundance and total biomass but the highest abundance of herbivorous nematodes of the order Tylenchida, especially Filenchus, Malenchus, and Paratylenchus, and a high abundance of identified genera of predators. The number of identified nematode genera, abundance, total biomass, and diversity index were the highest in young 0–20-year-old stands, and the lowest in 100–120-year-old stands. Enrichment, structure, and basal indices were influenced by both the stands and the ages of the forests.

The Communities of the Nematodes, Bacteria, and Fungi and the Soil’s Organic Matter in an Agroforestry Ecosystem in Croatia

An above‐ground plant diversity affects a below-ground biodiversity. A soil fauna diversity is important for the ecosystems’ sustainability. It reflects both the abiotic conditions and the soil’s biotic activity. This study’s objective was to assess the effect of an agroforestry system on the nematode abundance and trophic group distribution and on the bacterial and fungal abundance in the soil, as well as to analyze the links between a nematode abundance, trophic group patterns, soil’s microbiological status and the organic matter. A field experiment was conducted during two years in three treatments and three sampling periods. The treatments were as follows: an agricultural crop (C), a permanent walnut plantation (W), and a permanent walnut plantation with an agricultural crop (C + W). The nematodes were extracted, counted, processed and mounted on slides and ultimately determined and assigned to the trophic groups. The bacteria and fungi were extracted from the soil, grown on the plates, and counted. Our findings suggest that the studied agroforestry system (C+W) has exerted a positive effect on the soil nematodes, bacteria, and fungi, manifested as the statistically highest abundance of bacteria and fungi, but also as the highest abundance of nematodes and of a diversity of the nematode genera. The highest content of the organic matter was detected in the treatment C + W in the first sampling and in the treatments C + W and W in the second sampling. We have concluded that the combination of an agricultural crop and a permanent plantation has a great potential for better ecosystem stability and sustainability regardless of some deviations in our results. We believe that further research is necessary because the different agroforestry ecosystems may have different impacts on the soil fauna.