Assessing the Relative Efficiency of Termite Sampling Methods along a Rainfall Gradient in African Savannas

Seasonal variations in temperature and moisture are strong drivers of biological activity and diversity. Termites are an important insect group previously shown to respond to seasonal variation, but results are mixed with unclear patterns across habitat types. We investigated seasonal variation in termite species density, activity levels and assemblage composition across three seasons (wet, transitional and dry) and four savanna types across a rainfall gradient (450–900 mm year−1) in South Africa using cellulose baits. Termites responded to seasonality in all savannas investigated, with lower species density and activity levels during the dry season compared to the wet and transitional seasons. In the more arid sites (≤550 mm rainfall per year) activity levels were highest in the wet season, while at wetter sites (≥750 mm rainfall per year) the highest activity was recorded in the transitional season. Assemblage composition did not differ much between seasons across all sites, but differences in both composition and activity levels across seasons were more pronounced in wetter sites compared to drier ones. Our results demonstrate that seasonal patterns in termite diversity vary with mean annual rainfall, with larger variation in wetter habitats where climatic variation between seasons is greater.

Summary1. Fire is an important disturbance in African savannas where it is generally assumed that high levels of pyrodiversity (variation in aspects of the fire regime) are necessary to maintain high levels of biodiversity. There is, however, little empirical evidence in support of this hypothesis for animals. Furthermore, the relationship between pyrodiversity and biodiversity may vary with different savanna types, shaped by mean annual precipitation.2. We made use of a long‐term burning experiment to investigate the effect of interactions between precipitation and pyrodiversity on biodiversity. We sampled termites (major ecosystem engineers in savannas) within experimental plots involving a range of fire seasons and frequencies. Sampling was conducted in three distinct savanna types along a rainfall gradient in South Africa. We explored how termite diversity varied with mean annual precipitation and whether faunal responses to fire regimes varied with rainfall. Termites were sampled comprehensively during the wet season using cellulose baits and active searching in order to sample a variety of functional groups.3. Assemblages differed significantly across savanna types with higher levels of diversity in the wetter site using the active searching method. Diversity was lowest at the most arid site but certain feeding groups (FGs) peaked in the savanna with intermediate rainfall. Differences between these savannas are attributed to broad underlying changes in net primary productivity and temperature, with mammalian herbivores thought to generate a peak in diversity of some faunal groups at the intermediate savanna through their role in facilitating nutrient cycling.4. Overall, termites were highly resistant to fire in all savanna types with little difference between fire regimes (season and frequency), but assemblage composition and some FGs were affected by burning. Differences between fire regimes were more pronounced with increasing rainfall. These differences are likely to be linked to changes in vegetation structure caused by fire, which are more significant in wet savannas.5. Synthesis and applications. Our findings, along with those for other insect taxa, indicate limited support for the pyrodiversity–biodiversity hypothesis; this suggests that, at least for invertebrates, management regimes can be flexible, although more caution is advisable in wetter savannas.

Termites play an important role in the aeration and fertilization of soils where they abound. However, cultural practices influence their ecology. This study, which took place in Azaguié in the south of Côte d'Ivoire, aimed to know the diversity of termites that colonize cocoa plantations in comparison with the natural area. Three age classes of plantations have been defined: PC1 (from 0 to 5 years), PC2 (6 to 10 years old) and PC3 (over 30 years old). In each class of plantations, three transects 100 m long each, subdivided into 20 sections of 10 m2 (10 m x 2 m) have been demarcated. Three (3) monoliths were also dug by transect in order to know the density of hypogeal termites. Old plantations were more diversified with 18 species compared to plots PC1 (14 species) and PC2 (16 species). The natural area recorded the highest specific richness with 21 species sampled. The relative abundance of fungal termites in transects showed a high adaptability of these insects (18 occurrences in plots PC1 to 26 occurrences in natural area). With hypogeal termites, 16 species have been collected in all habitat types. The Jaccard Similarity Index showed large differences between species of hypogenous termites according to habitat types. No significant difference was observed between termite densities in selected plots. However, the distribution of termites in the depth of the soil was unevenly distributed and the surface layer of 0 - 10 cm concentrated the majority of termites. Cocoa production influences termite diversity and density, but the cessation of agricultural activities results in the recomposition of termite biodiversity.

Termites are widely distributed, and the highest number of genera are documented for the Afrotropical region. Nevertheless, data or species lists for southern Africa were mainly compiled by a few scientists during several field surveys between the 1950s and 1970s. However, knowledge about the diversity and endemism of termites in highland areas was not collated during these surveys and has not been assembled to date. Since then, different scientists used these datasets to measure the species richness or the endemic species richness for single countries, e.g., South Africa. Termite species lists for Angola are scarce and were compiled for only a few regions, where 10 of 93 species were found to be endemic. Our current knowledge about the termite species diversity in Namibia is substantially better, with 8 of 54 species from four families being endemic. However, recent molecular studies on single termite species show high genetic diversity. More research on the currently available material in collections as well as molecular studies on species from southern Africa is needed.

Land use effects on termite assemblages in Kenya

A survey was conducted on five farms in former Damaraland, a communal farming area in arid northwestern Namibia. The aims of the survey were to establish termite inventories for each site and to investigate whether termite diversity is determined by land-use history and land-use intensity. Overall, termite diversity in western Namibia is low. The Shannon Index ranged from 0–1.46. Diversity was generally higher at sites under relatively low land-use intensity. On the farm with the most arid climatic conditions, this relationship was reversed, probably as dung and other resource inputs were relatively high at the higher land-use intensity site. Termite species assemblages differed between the various farms, as wellas across the land-use intensity gradients. Whether this was attributable to differing environmental parameters or land-use histories was not clearly discernible.

Termites are ecosystem engineers that play an important role in the biotransformation and re‐distribution of nutrients in soil. The dry forests are endemic repositories, but at same time, they are most threatened by extensive livestock and crop farming, fires, and climate change. In Colombia, the best‐protected dry forests are located in the north. The termite fauna of dry forests are poorly known. The aim was to identify the termite species occurring in tropical dry forests of the Colombian Caribbean coast in relation to diet and precipitation, temperature, elevation, and soil properties. A total of 32 species in 1,103 occurrences were found. Termitidae accounted for 78% of the species richness with the Anoplotermes‐group, Microcerotermes, and Nasutitermes being the dominant genera. Differences in species composition and abundance were found across sites. These differences may be linked to anthropogenic disturbance and polygyny and polydomy. Strikingly, our highest elevation site (334 m) had the highest species richness much higher than the two lower elevation sites. This implies an inversion of the common elevation‐diversity gradient, also found for termites which can be explained by increasing precipitation with elevation in the dry forest. An analysis of termite species richness at the global scale confirms that termite species richness correlates positively with rainfall. Hence, rainfall seems to positively affect termite diversity. In line, the studied Colombian tropical dry forests had low diversity compared to rain forests. A decline of species‐rich soil‐feeding termites with increasing aridity may explain why the highest termite diversity occurs in humid tropical rain forests.Abstract in Spanish is available with online material.

Termite infestation is one of the fundamental problems associated with the loss of urban trees and ecological services. However, no such study has been performed in Pakistan to investigate the termite occurrence and assess such damages to urban trees caused by termites. For Lahore, research and comparable data on urban tree damages are rare or missing. This study surveyed six different microhabitats, including Bagh-e-Jinnah, canal vegetation, Model Town Park, Jallo Forestry, Race-Course Park, and FC College Vegetation employing the three belt transects (100 × 5m) method. We geo-referenced termite-infested trees to investigate the termite occurrence on living and dead standing trees, termite diversity, and the assessment of tree damage by termites' attack. We recorded four termite species (Odontotermes obesus Rambur, Coptotermes heimi Wasmann, Heterotermes indicola Wasmann, and Microtermes obesi Holmgren) representing two families (Rhinotermitidae and Termitidae). However, the diversity indices revealed that O. obesus (higher termite) and C. heimi (lower termite) were dominant with 46.60 and 36% of occurrence among observed trees, respectively. Kernel density function indicated that the Lahore Canal and Bagh-e-Jinnah plantation shared all four termites' infestation evenly compared to other study sites. We observed the maximum number of damaged trees by termites in canal vegetation with the most damaged exotic tree species Populus euramericana along the canal green belt. Additionally, we observed significant (P < 0.05) termite-tree interactions with exotic, living, and dead standing tree species and found termite colony size positively (R = 0.985) correlated with the tree trunk diameter up to breast height (DBH). The average population of termites per unit volume of deadwood log was (0.39/cm3) within all plantation sites. In conclusion, this study provides simple, reckless, and inexpensive knowledge about the assessment of termite damage to trees, which may give a better idea in making decisions on tree selection and management in urban ecosystems.

Through their role as ‘ecosystem engineers’, termites provide a range of ecosystem services including decomposition, and carbon and nitrogen cycling. Although termite diversity levels differ between regions as a result of variation in regional species pool size, in general, termite diversity is thought to decline with elevation. This study (1) investigated how termite species density, abundance, functional group diversity and termite attack on dead wood vary with altitude along an Amazon–Andes altitudinal gradient in Peru; (2) identified likely environmental causes of this pattern; and (3) explored the implications of termite presence for ecosystem functioning (notably for decomposition). Termites were sampled with a standardized 100 � 2 m straight-belt transect at five undisturbed forest sites along a gradient 190 to 3025 m, as were environmental variables and termite and fungus attack on dead wood. Termite diversity was similar to that found at comparable sites in South America, and there was little turnover of assemblage composition with elevation suggesting that montane specialists are not present. Termite diversity declined with increased elevation, though the upper distribution limit for termites was at a lower elevation than anticipated. We suggest that key drivers of this elevation pattern are reduced temperature with altitude and midelevation peaks in soil water content. Also, attack on dead wood diminished with decreasing termite indirect absolute abundance, while the depth of the soil humic layer increased. We hypothesize that termite abundance is a major accelerant of decomposition rates (and associated mineralization) in Amazonian forests.

BackgroundSavanna ecosystems support a diversity of biota and are influenced by vegetation and edaphic characteristics, shaping resident communities. This study was carried out at Mlawula nature reserve, a protected savanna ecosystem to determine impacts of vegetation and edaphic characteristics on termite species and functional diversity, as well as their activity. Termites were sampled from November 2017 to March 2018 in two habitat types, i.e. encroached and non-encroached by Dichrostachys cinerea over five months.ResultsTwelve genera were collected over the study period, dominated by Microtermes sp. Termite species diversity and populations were significantly between habitat types, with higher numbers and species in non-encroached sites. Four functional groups (FG) were collected from both habitat types, with FGII being the most dominant group in both and no significant differences in FG diversity between the habitat types. Of the vegetational and edaphic variables measured, only canopy cover was significantly different between habitat types and was higher in encroached sites. Intensity and frequency of attack were significantly higher in non-encroached sites, indicating a decline in termite activity in encroached sites.ConclusionsResults indicated that, with the exception of canopy cover, vegetational and edaphic characteristics are not affected by increased woody vegetation invasion within the system assessed. However, due to reduction in termite diversity and activity, increased woody vegetation invasion is a threat to termites and associated ecosystem services they provide. The investigation provided information at both community and ecosystem level for the savanna assessed on the need for insect conservation both within protected areas and surrounding landscapes. Since the study suggested that termite populations and associated activity could be reduced due bush encroachment, monitoring of the impacts of increasing woody plant invasions is essential for insect conservation and maintenance of savanna ecosystem function and heterogeneity.

The aim of this survey was to evaluate three field termite sampling methods to investigate whether there is a method for the evaluation of termite diversity which does not require experienced personnel. The sampling methods included the cattle dung method, toilet paper roll method and the visual searching (scouting) method. The methods were evaluated in a transect of 2 × 100 m in cattle grazing lands during the dry and wet seasons. Thirteen species from eight genera and three subfamilies were recorded with all three methods. The results for the number of species detected revealed differences between the three methods with 57%of the termite species found using the transect search method, 29%of the species were attracted to the cattle dung bait and 14%attracted to the toilet roll bait. The most abundant species, based on the number of encounters, was for individuals in the Odontotermes genus 15 (33 %), followed by Microtermes 12 (27 %). A higher Shannon diversity index (1.80) was recorded with the transect search method, followed by the cattle dung bait method (1.54), while the toilet roll bait method recorded the lowest diversity index (0.95). Results of the Chao2 and Jackknife estimators showed that all the methods underestimated the taxa present. A combination of the transect search method and the cattle dung bait method is recommended for monitoring termite diversity.

Predicting species distributions with changing climate has often relied on climatic variables, but increasingly there is recognition that disturbance regimes should also be included in distribution models. We examined how changes in rainfall and disturbances along climatic gradients determined demographic patterns in a widespread and long-lived tree species, Callitris glaucophylla in SE Australia. We examined recruitment since 1950 in relation to annual (200–600 mm) and seasonal (summer, uniform, winter) rainfall gradients, edaphic factors (topography), and disturbance regimes (vertebrate grazing [tenure and species], fire). A switch from recruitment success to failure occurred at 405 mm mean annual rainfall, coincident with a change in grazing regime. Recruitment was lowest on farms with rabbits below 405 mm rainfall (mean = 0–0.89 cohorts) and highest on less-disturbed tenures with no rabbits above 405 mm rainfall (mean = 3.25 cohorts). Moderate levels of recruitment occurred where farms had no rabbits or less disturbed tenures had rabbits above and below 405 mm rainfall (mean = 1.71–1.77 cohorts). These results show that low annual rainfall and high levels of introduced grazing has led to aging, contracting populations, while higher annual rainfall with low levels of grazing has led to younger, expanding populations. This study demonstrates how demographic patterns vary with rainfall and spatial variations in disturbances, which are linked in complex ways to climatic gradients. Predicting changes in tree distribution with climate change requires knowledge of how rainfall and key disturbances (tenure, vertebrate grazing) will shift along climatic gradients.

Fire plays an integral role in shaping the vegetation structure of savanna ecosystems. However, the effects of fire regime characteristics, such as frequency and season of burn, on savanna vegetation structure, biomass and tree abundance across landscape types are largely unknown. We used high‐resolution airborne light detection and ranging (LiDAR) to investigate the long‐term effects of fire manipulation on savanna vegetation in Kruger National Park, South Africa. We analysed the effects of fire exclusion and experimental burns every 1, 2, 3, 4 and 6 years and during different seasons on aboveground biomass (AGB), tree stem densities and vegetation vertical height profiles across a rainfall gradient and on contrasting geologies. Across savanna types, and especially in drier savannas, fire season was more influential for constraining AGB than fire frequency. Plots experiencing fires during the late‐ and mid‐dry season had 44.50% and 43.60%, respectively, lower AGB relative to unburnt plots than wet‐season fires. However, in mesic savannas, fire frequency interacted with fire season to influence AGB: plots subjected to high frequency, dry‐season fires had 55.35% lower AGB than unburnt plots, whereas plots burnt in the wet season at lower frequencies had lower AGB (24.40% lower than unburnt plots) than plots subjected to high frequency, wet‐season fires (13.74% lower AGB than unburnt plots). Fire regimes had variable effects on tree densities, and effects varied with the savanna type. Woody vertical vegetation profiles showed the largest differences in response to dry‐season fires, with the greatest divergence in vegetation height classes &lt;5 m. Synthesis and applications. Understanding the influence of fire regimes on vegetation structure has important implications for the management of savanna heterogeneity and for predicting trajectories of change in savanna vegetation as fire regimes vary with climate change. We show that the magnitude of the effect of fire on woody vegetation structure varies with savanna context. Our results suggest that heterogeneous vegetation structure can be achieved by applying fires in the dry season in mesic savannas, whereas in dry savannas, variation in fire regimes is less consequential for constraining biomass accumulation and altering vegetation structure.

Termites are gradually being recognized as emerging pests and a major constraint to the sustainable production of cocoa in Côte d’Ivoire, the world’s leading cocoa producer. In order to develop environmentally compatible management strategies against the pest species, it is important to identify the termite species in these systems and have a better understanding of their functional diversity. This study was conducted to evaluate the effect of shade management on the diversity of termites in different cocoa growing systems in the Nawa area, one of the main cocoa producing areas in Côte d'Ivoire. The study also evaluated the effect of shade cover on termite damage to cocoa. Sampling was done using a modified standardized transect method, where termites were collected in 25 m x 2 m transects, placed in 30 m x 30 m quadrats. Termites sampled were identified and grouped according to feeding habits. Twenty-nine (29) termite species, in 17 genera and 7 subfamilies under 3 families were sampled. These termite species are distributed among the four feeding groups. Fungus-growers and wood-feeders were the most diversified. The intermediate shade systems were the least attacked by termites compared to the full sun system and shaded system. Shade therefore, seems to influence termite biodiversity and damage in cocoa agroforestry systems. We recommend awareness-raising and assistance from cocoa farmers on shade management and the choice of an appropriate cropping system such as an intermediate shade system that would reduce termite attacks, produce long term and preserve biodiversity.

Termites are generally regarded as pests, although they have some beneficial roles to play in the ecosystem, particularly in the soil. This study was conducted between January 2018 and April 2018, to determine the effect of physico-chemical parametrs on abundance and diversity of termites and other arthropods in termite mounds in Uinversity of Uyo Community. Soil samples were randomly collected from six termite mounds from two sites for physiochemical parameters analysis and these were temperature, pH, moisture content, nitrogen, phosphorus, magnesium, copper, sodium, potassium, manganese and iron.. The termites and other arthropods were preserved in 70% ethanol. Temperature and moisture content, copper, sodium and iron were significant. The results revealed that the physicochemical parameters affected the termite species abundance as station 1 (539) had relatively more of the termite species than station 2 (551), and also affected the diversity of the termites as station 1 (0.89) had relatively more diversity of the termites than station 2 (0.66). Also from the results, station 1 (2.06) had relatively more diversity of the other arthropod species identified in the study area than station 2 (1.59). Macrotermes bellicosus and Odontermes badius termite species were identified. Musca domestica, Anopheles gambiae, Lasius sp, Archispirostreptus sp, Camponotus sp, Missulena sp, Chorthippus sp, Acheta sp and Blatta orientalis were the other arthropods collected and identified. Macrotermes bellicosus (59.93 %; 63.52 %) was the most abundance and dorminant of the termite species identified in the study areas. Lasius sp (45; 25.93 %)