Next Article in Journal
Diversity and Distribution Characteristics of Culturable Bacteria in Burqin Glacier No. 18, Altay Mountains, China
Previous Article in Journal
Destiny of Two Caddisfly Species under Global Climate Change
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Diversity
Volume 15
Issue 9
10.3390/d15090996
diversity-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Communication

Effect of Long-Term Burning and Mowing Regimes on Ant Communities in a Mesic Grassland

by
Lindiwe R. Khoza
1,
Alan N. Andersen
2 and
Thinandavha C. Munyai
1,*
1
School of Life Sciences, University of KwaZulu-Natal, Private Bag X 01, Scottsville 3209, South Africa
2
Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, NT 0909, Australia
*
Author to whom correspondence should be addressed.
Diversity 2023, 15(9), 996; https://doi.org/10.3390/d15090996
Submission received: 21 July 2023 / Revised: 1 September 2023 / Accepted: 5 September 2023 / Published: 6 September 2023
(This article belongs to the Section Biodiversity Loss & Dynamics)
Browse Figures
Versions Notes

Abstract

:
Ecological disturbance is fundamental for grassland management and the maintenance of its biodiversity. Fire and grazing are the primary habitat disturbances influencing the structure and composition of grassland ecosystems, both acting to remove grass biomass. Little is known about the effects of such grass biomass removal on grassland ants, an ecologically dominant faunal group. Our study assesses the response of ant communities to long-term experimental burning and mowing treatments in a South African mesic grassland. The study’s main objectives were (i) to assess the effect of frequency and season of burning and mowing on ant species richness and composition and (ii) to identify indicator species associated with the various grassland management treatments. The experiment included two fully crossed fire treatments: frequency (annual, biennial, and triennial) and season (late winter and after spring rains), along with annual mowing and an undisturbed control. Ants were sampled using pitfall traps in 27 plots, comprising 18 burnt, 6 mown, and 3 controls. The mean species richness in the burnt plots (22.38 ± 3.71) was far higher than in the control (23 ± 2.0) or mown (21.0 ± 2.28) plots. However, the total richness (combining plots) did not vary among treatments. Four of the nine most common species showed a statistically significant response to experimental treatment, but there were no significant treatment effects on overall species composition. Three indicator species (IndVal > 70%) were identified for the control plots, and detector species (IndVal 50–70%) were identified for annual, biennial, and triennial burning treatments. Our findings demonstrate that ant communities in this grassland system are highly resilient to burning and mowing, and that fire promotes diversity at the plot scale. Our identified indicator and detector species can be used as a focus for ongoing monitoring of biodiversity change in our grassland system, including in response to woody expansion.

1. Introduction

Ecological disturbance, defined as any factor that removes biomass [1,2], is fundamental for the maintenance of grassland biodiversity and therefore its conservation management [3]. The impacts of disturbance on biological communities depend on its frequency, intensity, timing, and patchiness [4,5,6]. Inappropriate disturbance regimes have led to grassland degradation globally [3]. For example, overly frequent or infrequent burning of grasslands can reduce plant diversity, cause significant shifts in species composition, and lead to reduced ecosystem stability [7].
In grassland ecosystems, fire and grazing are the primary agents of disturbance and the most widely used tool for land management [5,8]. Grass biomass removal by fire and grazing affects community dynamics through changes in vegetation structure, food supply, and competitive interactions [4,9]. Fire and grazing both have a direct effect on vegetation through the removal of plant biomass, and grazing has additional effects through its selectivity based on palatability, along with trampling and defecation [10,11]. Trampling by livestock leads to soil compaction and defecation leads to changes in soil nutrients [11]
In managed grasslands, mowing (hay cutting) is another source of biomass removal influencing the biotic composition and community structure [12]. Like any other disturbance, mowing has indirect impacts on fauna through changes in vegetation structure, floristic composition, food supplies, and nesting sites [13,14]. Arthropods can also be directly affected through mortality during mowing.
Most studies of the effects of fire on grassland ecosystems of southern Africa have focused on grass production and biomass plants [15,16,17,18]. Few southern African studies [9,19,20] have examined the effect of fire and mowing on invertebrates. Here, we investigate how ants respond to long-term, experimental burning and mowing regimes in a South African mesic grassland.
Ants are a dominant group of invertebrates that contribute a large proportion of faunal biomass [7,21,22]. They are taxonomically and functionally diverse species that occupy diverse trophic guilds as herbivores, predators, and omnivores [23], playing important roles in nutrient cycling and energy flow [24]. As indicators of ecosystem function, ant communities often reflect the ecological impact of habitat disturbance more generally [8]. The effects of prescribed burning or mowing regimes on ant assemblages are primarily indirect through changes in habitat structure [10,25], which influences microclimate, resource availability, nesting sites, and competitive interactions [10,13].
Disturbance-induced reductions in vegetation cover favour arid-adapted taxa (characterized by high thermophilia) such as those belonging to Dominant Dolichoderinae and Hot-climate Specialists [26,27] at the expense of those that prefer closed habitats such as Cryptic Species, Cold-climate Specialists, and Specialist Predators [7,28]. A global review [28] showed that fire had a negative effect on ant diversity in forests with no effect on deserts, grasslands, and savanna vegetation types. In Kruger National Park, burning had no major effect on the abundance and species richness of savanna ants [25].
Here, we use a long-term (established in 1950) experiment on Ukulinga Research Farm in KwaZulu-Natal [14] to assess the effect of disturbance on ant communities. The objectives of the study were to assess (i) the effect of frequency and season of burning and mowing on ant species richness and composition, and (ii) to identify indicator species associated with the various treatments.

2. Materials and Methods

2.1. Study Site Description

Our study was conducted on the Ukulinga Research Farm (29°40′ S; 30°24′ E), of the University of KwaZulu-Natal in Pietermaritzburg, South Africa. Ukulinga Research Farm is 8 km south of the University of KwaZulu-Natal, Pietermaritzburg, with an altitude between 715 to 850 m a.s.l. [29]. Mean annual precipitation in this area is approximately 790 mm, occurring mostly during summer (September–April) as convective storms. Summers are warm to hot with a mean maximum temperature of 26.4 °C in February, and winters are mild with occasional frost and a mean maximum temperature of 13.2 °C in July. Ukulinga Research Farm grassland is classified as the Southern Tall Grassveld, which falls under the Midlands Mistbelt Grassland Vegetation unit [29]. This grassland occurs on a hilly landscape dominated by tall grasses such as Themeda triandra, Hyparrhenia hirta, Panicum maximum, and Tristachya leucothrix, along with numerous forb species. The most common woody tree species are Senegalia karoo, S. nilotica, S. mearnsii, and Celtis africana. Soils on the research farm are considered to be acidic and relatively infertile and classified as the Westleigh type (Soil Classification Working Group 1991) [30].

2.2. Experimental Design

The long-term grassland experimental trials at Ukulinga were established by J.D Scott in 1950 as reported by Chambers and Samways [19]. These plots were initially designed to determine the effect of burning and mowing in different seasons and intervals on yield quality, soil nutrient cycles, and grassland composition [15,30]. There are no published studies on the local ant community. The experiment was laid out as three adjacent blocks (three replicates), each divided into randomized experimental plots (13.76 × 18.35 m) that are 4 m apart (Supplementary Material Figure S1). Each plot was subjected to a different combination of burning and mowing regimes with dormant-season removal of treatments. Burning and mowing treatments were separately applied. Treatments range from plots burnt three times annually and plots completely protected from disturbance since 1950 (referred to as control hereafter). Mowing was applied annually, and burning was applied at three frequencies: annual, biennial, and triennial.
Sampling occurred in a total of 27 plots (18 burnt, 6 mown, and 3 undisturbed control plots covering all three blocks that are <50 m (Figure S1). Burning treatments comprised annual burn in spring, annual burn in late winter; biennial burn in spring, biennial burn in late winter; and triennial spring burns. In all cases, burning was conducted after the first spring rain. Mowing treatments consisted of annual mowing in late winter, and annual mowing after the first spring rain (Figure S1).

2.3. Ant Sampling and Species Identification

Standardized pitfall trapping following [31] was used to sample ants during both the wet (March 2019) and dry (July 2019) seasons. Each of the 27 plots had 12 pitfall traps (each trap was 62 mm in diameter, 110 mm in height, and 500 mL volume) laid out in a 3 × 4 grid with 4 m spacing between adjacent traps. To limit edge effects, traps were at least 6 m from a plot edge. Pitfall traps were quarter-filled with 50% propylene glycol solution, which neither repels nor attracts ants [31], and were left open for five days. Traps were then collected and taken to the laboratory, where samples were processed and stored in 70% ethanol. Ants were counted and identified to the species level, and species names were confirmed through comparison with a reference collection kept at the University of KwaZulu-Natal, Pietermaritzburg campus, along with images in AntWeb (http://antweb.org, accessed on 15 February 2020), and AntCat (http://antcat.org, accessed on 25 February 2020). For those that could not be identified to the species level, Fisher and Bolton [32] was used to identify these specimens to the genus level and they were given code numbers (e.g., UKZN_01, etc.). Ant genera and species groups were further classified into functional groups following Andersen [26]. Voucher specimens were mounted and deposited at the Iziko Museum of Cape Town, South Africa.

2.4. Data Analysis

For all analyses, data were analysed at the plot level. Sample coverage for species richness and sample completeness was analysed in the iNEXT online software program [33]. Generalized linear models (GLMMs) using a log link function and Poisson error distribution were used to test the effects of burning frequency and burning/mowing season on ant species richness, abundance, and the abundances of each of the most common species. Only species with >50 individuals occurring across burning/mowing treatments were considered for species-level analysis, as they were common enough for the analysis. Burning frequency and burning/mowing season treatments were included in the model as fixed factors, while replicates were included as random factors in the model to account for pseudoreplication. The GLMMs were run using the vegan and multicomp package in R studio version 3.5.1 program [34].
Variations in species composition among treatments were examined through non-multidimensional scaling (NMDS) based on the Bray–Curtis dissimilarity and square root transformation in the PRIMER version 6 software program [35]. Analysis of similarity (ANOSIM) with 999 permutations was used to test for significant differences in composition among burning frequency (annual, biennial, triennial burn), burning/mowing season (spring, late winter), and unburnt (control) plots.
Indicator species for each treatment type were identified using the Indicator Value Method (IndVal) in the R program version 3.5.1 [34] based on abundance data. IndVal measures the degree to which it fulfils the criteria of uniqueness (specificity) and fidelity (frequency within a treatment) for each treatment type [36]. Species with higher IndVal values (%) are regarded as reliable indicators because of their probability of being sampled [36,37]. In this study, species with IndVal > 70% were considered indicator species for that treatment type, and species with IndVal from 50–70% were regarded as detector species [36,37].

3. Results

3.1. The Ant Fauna

We recorded a total of 14 502 individual ants, comprising 67 species in 29 genera (Table S1). The most specious genera were Tetramorium (14 species), Lepisiota (6), Monomorium, and Solenopsis (5 each). The most abundant species were Pheidole sp. 2 (megacephala gp.), representing 24.7% of total ant abundance, Crematogaster rectinota (8.8%), Acropyga sp. 1 (6.9%), Tetramorium sp. 3 (setigerum gp.) (6.5%), and Lepisiota capensis (4.8%). Species rarefaction curves (Figure 1a,b) based on individuals approximated an asymptote, with a sample coverage > 0.95 for all treatments and seasons of treatments. There were no differences in total species richness among treatments or seasons as the confidence intervals of the curves were overlapping (Figure 1a,b).

3.2. Species Richness and Abundance

There was no significant difference in species richness (F = 0.347, df = 4, p = 0.846; Figure 2) between burnt plots subjected to different burning seasons. The mean species richness in burnt plots (22.38 ± 3.71) was higher than in control (23 ± 2.0) and mown (21 ± 2.28) plots. However, the total richness (combining plots) did not vary among treatments (F = 0.498; p = 0.614; Figure 3).
A total of 27 species were recorded exclusively in the burnt treatments compared with only 2 (Lepisiota UKZN_08 (spinosior gp.) and Tetramorium UKZN_19 (squaminode gp.) in the control plots (Table S2).
Four of the nine most common species showed a statistically significant response to experimental treatments (Table 1, Figure 4). The most marked was for Crematogaster rectinota, which occurred primarily in annually burnt plots and was not recorded at all in control plots. Although occurring across all plots, Pheidole UKZN_02 (megacephala gp.) was most common in control plots. Acropyga UKZN_01 was most abundant in annual burn and least in control plots, whereas Tetramorium UKZN_03 (setigerum gp.) preferred triennial burn plots compared to annual burn plots (Figure 4 and Table S2).

3.3. Species Composition

ANOSIM revealed that ant species composition did not vary significantly with treatment (Global R = 0.07, p = 0.145; Figure 5a) or with the season of treatment (Global R = 0.015, p > 0.05; Figure 5b).

3.4. Indicator Species

IndVal revealed that the control treatment had three indicator species and the biennial and triennial burn treatments each had one detector species (Table 2). No indicator or detector species were found for the annual burn or annual mow treatments.
The burning and mowing treatments varied markedly in functional group composition (Figure 6). The most frequently recorded functional groups were Generalized Myrmicinae (mostly species of Pheidole and Crematogaster) in control plots representing a greater proportion of ants (90.3%). Cryptic species (8%) functional group (mostly Solenopsis and Acropyga) in annual mown plots, Tropical Climate Specialists (mostly Anoplolepis) in annual mown plots, and specialist predators (species of Leptogenys and Mesoponera) in control plots, while subordinate Camponotini (species of Camponotus) was the least frequently recorded functional group in biennial plots (Figure 6).

4. Discussion

Fire and mowing are important management tools for grassland maintenance and diversity. We investigated how ants respond to long-term experimental burning and mowing regimes in a South African grassland by determining the effect of burning frequency and burning/mowing season on ant species richness and composition. We further identified indicator species associated with burning and mowing treatments.
We found that mowing had no significant effect on ant species richness, as is the case for grasslands of Central Europe [38]. However, burning dramatically increased ant species richness at the plot scale, as is the case in Australian savannas [21]. This can be explained by fire increasing habitat openness and therefore creating a more thermally favourable microclimate for ants, given that most species are thermophilic [7,39]. However, the intensity and frequency of biomass removal will determine the impact on ant diversity and composition, with the effects on species richness expected to follow the intermediate disturbance hypothesis, where the highest richness occurs at intermediate levels of disturbance [40].
A previous study in South African grassland showed a significant effect of fire season on ant species richness [9]. However, this was not the case in our study. Our findings are congruent with a previous study that investigated grasshoppers in our experimental system. For example, the season of burn similarly did not affect the mean species richness and abundance of grasshoppers [19]. This might be because the fire occurred in autumn and most invertebrate species hibernate during the winter season or are in dormant stages of their life cycles, making them less affected [9].
We found no detectable effect of either mowing or fire treatments on species composition, revealing that ant communities in our study appear to be highly resilient to such disturbances. This is consistent with results from the long-term fire experiment in South Africa’s Kruger National Park, where fire frequency and season had minimal effect on ant species composition [26]. Similarly, savanna ant communities in Australia showed no significant difference between sites burnt annually and biennially, and there was substantial overlap between these sites and those burnt less frequently [41]. Ant species composition has more generally been documented to be resilient to fire [8,27,42], especially those with an evolutionary history of frequent fire [43].
Four of the nine most common species showed a statistically significant response to experimental treatment. Crematogaster rectinota, Acropyga UKZN_01, and Tetramorium UKZN 03 (setigerum gp.) occurred most commonly in disturbed plots. In addition, Tetramorium UKZN_19 (squaminode gp.), Camponotus UKZN_05 (maculatus gp.), and Tetramorium nr grassi were significant indicators of control plots. Pheidole UKZN_02 (megacephala gp.) was most common in control plots. Species of Pheidole, Crematogaster, and Tetramorium are highly generalized ants that can tolerate a wide range of environmental conditions [2,26,44] and are often in terrestrial ecosystems [27]. They would make useful indicator species for ongoing monitoring of fire impacts.
Changes in vegetation structure not only affect ant species diversity, but also affect food resource availability (e.g., presence of plants offering nectar and honeydew-producing hemipterans) and the competitive ability of species [45,46]. Plants supplying nectar at high rates attract many insects, including ant species. In our study, the control plots were mostly dominated by Lantana camara, which is known to attract ants that feed on nectar [47]. This may explain the high abundance of Pheidole UKZN_02 (megacephala gp.) in these plots because they are ecologically dominant species that monopolize food and thereby reduce the abundance of other ant species [39,48]. The genus Pheidole is composed of omnivores that compete for the same food resources as subordinate ants such as Camponotus species; therefore, temporal resource partitioning allows the coexistence of these competitors [48,49].
Three indicator species (Tetramorium sp. (squaminode gp.), Camponotus sp. (maculatus gp.), and Tetramorium nr grassi; IndVal > 70%) along with four detector species (IndVal 50–70%) were identified for control plots, and detector species were identified for annual, biennial, and triennial burning treatments. Detailed biological information is not available for any of these species, but they all appear to be generalist predators and scavengers that nest in the soil.

5. Conclusions

Ant communities in our grassland study system are highly resilient to disturbance by fire and mowing. This is consistent with other disturbance-prone grassy ecosystems in southern Africa [8] and elsewhere in the world [42,50]. This appears to be the case for arthropods more generally [43] and reflects a long evolutionary history in association with disturbance. Our identified indicator and detector species can be used as a focus for ongoing monitoring of biodiversity change in our grassland system, including in response to woody expansion.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/d15090996/s1, Figure S1: Experimental design and sampled treatment plots on Ukulinga Research Farm, Pietermaritzburg, South Africa. Treatments indicated by the following numbers: A1 = control; A2 = annual burn in winter; A3 = annual burn after the first spring rains; A4 = biennial burn in winter, A5 = biennial burn after the first spring rains; A7 = triennial burn in winter, A8 = triennial burn after the first spring rains; A10 = annual mow in winter, A11 = annual mow after the first spring rains; Table S1: Checklist of ant subfamilies and species with their abundances and richness within each treatment type (annual burn (AB); annual mow (AM); biennial burn (BB); control (CON) and triennial burn (TB)) sampled on Ukulinga Research Farm, Pietermaritzburg, KwaZulu-Natal; Table S2: Records of ant species across treatment type and season (late winter, control, and spring) of treatments.

Author Contributions

A.N.A. and T.C.M. designed and conceptualized the study; L.R.K. and T.C.M. collected the data; T.C.M. led the curation and identification of ant species. L.R.K. analysed and led the writing, under the supervision of A.N.A. and T.C.M. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the South African National Research Foundation, grant number 117566 to L.R.K. and grant number 114416 to T.C.M.

Institutional Review Board Statement

Permission to sample ants in the study site (Ukulinga Research Farm of the University of KwaZulu-Natal) was approved by Prof K.P Kirkman from the School of Life Sciences at the University of KwaZulu-Natal.

Informed Consent Statement

Not applicable.

Data Availability Statement

Data used in this study are available in Table S1.

Acknowledgments

We would like to convey our appreciation to the School of Life Sciences for granting us access to the study area, in particular Kevin P. Kirkman. We are grateful to Nokubonga Thabethe, Thandeka Mahlobo, Sphesihle Mkhungo, Sinenhlahla Mntambo, and undergraduate students for assisting with fieldwork.

Conflicts of Interest

The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.

References

  1. Grime, J.P. Plant Strategies, Vegetation Processes, and Ecosystem Properties; John Wiley and Sons: Chichester, UK, 2006. [Google Scholar]
  2. Andersen, A.N. Global ecology of rainforest ants: Functional groups in relation to environmental stress and disturbance. In Ants: Standard Methods for Measuring and Monitoring Biodiversity; Agosti, D., Majer, J., Alonso, L.E., Schultz, T., Eds.; Smithsonian Institution Press: Washington, DC, USA, 2000; pp. 25–34. Available online: http://hdl.handle.net/102.100.100/207377?index=1 (accessed on 21 March 2023).
  3. Kirkman, K.P.; Collins, S.L.; Smith, M.D.; Knapp, A.K.; Burkepile, D.E.; Burns, C.E.; Fynn, R.W.; Hagenah, N.; Koerner, S.E.; Matchett, K.J. Responses to fire differ between South African and North American grassland communities. J. Veg. Sci. 2014, 25, 793–804. [Google Scholar] [CrossRef]
  4. Socher, S.A.; Prati, D.; Boch, S.; Müller, J.; Klaus, V.H.; Hölzel, N.; Fischer, M. Direct and productivity-mediated indirect effects of fertilization, mowing and grazing on grassland species richness. J. Ecol. 2012, 100, 1391–1399. [Google Scholar] [CrossRef]
  5. Lessard, J.P. Ant community response to disturbance: A global synthesis. J. Anim. Ecol. 2019, 88, 346–349. [Google Scholar] [CrossRef] [PubMed]
  6. Arcoverde, G.B.; Andersen, A.N.; Leal, I.R.; Setterfield, S.A. Habitat-contingent responses to disturbance: Impacts of cattle grazing on ant communities vary with habitat complexity. Ecol. Appl. 2018, 28, 1808–1817. [Google Scholar] [CrossRef]
  7. Andersen, A.N. Responses of ant communities to disturbance: Five principles for understanding the disturbance dynamics of a globally dominant faunal group. J. Anim. Ecol. 2019, 88, 350–362. [Google Scholar] [CrossRef]
  8. Parr, C.; Bond, W.; Robertson, H. A preliminary study of the effect of fire on ants (Formicidae) in South African savanna. Afr. Entomol. 2002, 10, 101–111. Available online: https://hdl.handle.net/10520/EJC31890 (accessed on 23 March 2023).
  9. Uys, C.; Hamer, M. The effect of long-term fire treatments on invertebrates: Results from experimental plots at Cathedral Peak, South Africa. Afr. J. Range Forage Sci. 2007, 24, 1–7. [Google Scholar] [CrossRef]
  10. Philpott, S.M.; Perfecto, I.; Armbrecht, I.; Parr, C.L. Ant diversity and function in disturbed and changing habitats. In Ant Ecology; Lach, L., Parr, C.L., Abbott, K.L., Eds.; Oxford University Press: New York, NY, USA, 2010; pp. 137–156. [Google Scholar]
  11. Abensperg-Traun, M.P.; Smith, G.T.; Arnold, G.; Steven, D. The effects of habitat fragmentation and livestock-grazing on animal communities in remnants of gimlet Eucalyptus salubris woodland in the Western Australian wheatbelt I. Arthropods. J. Appl. Ecol. 1996, 33, 1281–1301. Available online: https://www.jstor.org/stable/2404770 (accessed on 23 March 2023). [CrossRef]
  12. Schmid, J.S.; Huth, A.; Taubert, F. Impact of mowing frequency and temperature on the production of temperate grasslands: Explanations received by an individual-based model. Oikos 2022, 2022, e09108. [Google Scholar] [CrossRef]
  13. Heuss, L.; Grevé, M.E.; Schäfer, D.; Busch, V.; Feldhaar, H. Direct and indirect effects of land-use intensification on ant communities in temperate grasslands. Ecol. Evol. 2019, 9, 4013–4024. [Google Scholar] [CrossRef]
  14. Humbert, J.-Y.; Ghazoul, J.; Walter, T. Meadow harvesting techniques and their impacts on field fauna. Agric. Ecosyst. Environ. 2009, 130, 1–8. [Google Scholar] [CrossRef]
  15. Fynn, R.W.; Morris, C.D.; Edwards, T.J. Effect of burning and mowing on grass and forb diversity in a long-term grassland experiment. Appl. Veg. Sci. 2004, 7, 1–10. [Google Scholar] [CrossRef]
  16. Uys, R.G.; Bond, W.J.; Everson, T.M. The effect of different fire regimes on plant diversity in southern African grasslands. Biol. Conserv. 2004, 118, 489–499. [Google Scholar] [CrossRef]
  17. Trollope, W.; Trollope, L.; Hartnett, D. Fire behaviour a key factor in the fire ecology of African grasslands and savannas. In Forest Fire Research and Wildland Fire Safety; Viegas, D.X., Ed.; Millpress: Rotterdam, The Netherlands, 2002; pp. 1–5. [Google Scholar]
  18. Tsvuura, Z.; Kirkman, K.P. Yield and species composition of a mesic grassland savanna in South Africa are influenced by long-term nutrient addition. Austral Ecol. 2013, 38, 959–970. [Google Scholar] [CrossRef]
  19. Chambers, B.Q.; Samways, M.J. Grasshopper response to a 40-year experimental burning and mowing regime, with recommendations for invertebrate conservation management. Biodivers. Conserv. 1998, 7, 985–1012. [Google Scholar] [CrossRef]
  20. Parr, C.L.; Chown, S.L. Burning issues for conservation: A critique of faunal fire research in Southern Africa. Austral Ecol. 2003, 28, 384–395. [Google Scholar] [CrossRef]
  21. Andersen, A.N.; Hertog, T.; Woinarski, J.C. Long-term fire exclusion and ant community structure in an Australian tropical savanna: Congruence with vegetation succession. J. Biogeogr. 2006, 33, 823–832. [Google Scholar] [CrossRef]
  22. Arnan, X.; Cerdá, X.; Rodrigo, A.; Retana, J. Response of ant functional composition to fire. Ecography 2013, 36, 1182–1192. [Google Scholar] [CrossRef]
  23. Hölldobler, B.; Wilson, E.O. Journey to the Ants: A Story of Scientific Exploration; Harvard University Press: Cambridge, MA, USA, 1994. [Google Scholar]
  24. Del Toro, I.; Ribbons, R.R.; Pelini, S.L. The little things that run the world revisited: A review of ant-mediated ecosystem services and disservices (Hymenoptera: Formicidae). Myrmecol. News. 2012, 17, 133–146. [Google Scholar]
  25. Parr, C.L.; Robertson, H.G.; Biggs, H.C.; Chown, S.L. Response of African savanna ants to long-term fire regimes. J. Appl. Ecol. 2004, 41, 630–642. [Google Scholar] [CrossRef]
  26. Andersen, A. Functional groups and patterns of organization in North American ant communities: A comparison with Australia. J. Biogeogr. 1997, 24, 433–460. [Google Scholar] [CrossRef]
  27. Andersen, A.N.; Vasconcelos, H.L. Historical biogeography shapes functional ecology: Inter-continental contrasts in responses of savanna ant communities to stress and disturbance. J. Biogeogr. 2022, 49, 590–599. [Google Scholar] [CrossRef]
  28. Hoffmann, B.D.; Andersen, A.N. Responses of ants to disturbance in Australia, with particular reference to functional groups. Austral Ecol. 2003, 28, 444–464. [Google Scholar] [CrossRef]
  29. Mucina, L.; Rutherford, M. The Vegetation of South Africa, Lesotho and Swaziland; Strelitzia: Pretoria, South Africa, 2006; Volume 19. [Google Scholar]
  30. Fynn, R.W.; O’Connor, T.G. Determinants of community organization of a South African mesic grassland. J. Veg. Sci. 2005, 16, 93–102. [Google Scholar] [CrossRef]
  31. Munyai, T.C.; Foord, S.H. Temporal patterns of ant diversity across a mountain with climatically contrasting aspects in the tropics of Africa. PLoS ONE 2015, 10, e0122035. [Google Scholar] [CrossRef] [PubMed]
  32. Fisher, B.L.; Bolton, B. Ants of Africa and Madagascar—A Guide to the Genera; University of California Press: Davis, CA, USA, 2016. [Google Scholar]
  33. Chao, A.; Ma, K.H.; Hsieh, T.C. iNEXT (iNterpolation and EXTrapolation) Online: Software for Interpolation and Extrapolation of Species Diversity. 2016. Available online: http://chao.stat.nthu.edu.tw/wordpress/software_download/ (accessed on 17 May 2021).
  34. R Core Team. R: A Language and Environment for Statistical Computing; R Foundation for Statistical Computing: Vienna, Austria, 2020; Available online: https://www.R-project.org/ (accessed on 11 April 2021).
  35. Clarke, K.R.; Gorley, R.N. PRIMER v6: User Manual/Tutorial (Plymouth Routines in Multivariate Ecological Research); PRIMER-E: Plymouth, UK, 2006. [Google Scholar]
  36. McGeoch, M.A.; Van Rensburg, B.J.; Botes, A. The verification and application of bioindicators: A case study of dung beetles in a savanna ecosystem. J. Appl. Ecol. 2002, 39, 661–672. [Google Scholar] [CrossRef]
  37. Botes, A.; McGeoch, M.A.; Robertson, H.G.; van Niekerk, A.; Davids, H.P.; Chown, S.L. Ants, altitude and change in the northern Cape Floristic Region. J. Biogeogr. 2005, 33, 71–90. [Google Scholar] [CrossRef]
  38. Dahms, H.; Wellstein, C.; Wolters, V.; Dauber, J. Effects of management practices on ant species richness and community composition in grasslands (Hymenoptera: Formicidae). Myrmecol. News. 2005, 7, 9–16. [Google Scholar]
  39. Hölldobler, B.; Wilson, E.O. The Ants; Harvard University Press: Cambridge, MA, USA, 1990. [Google Scholar]
  40. Connell, J.H. Diversity in tropical rain forests and coral reefs. Science 1978, 199, 1302–1310. [Google Scholar] [CrossRef] [PubMed]
  41. Andersen, A.N.; Ribbons, R.R.; Pettit, M.; Parr, C.L. Burning for biodiversity: Highly resilient ant communities respond only to strongly contrasting fire regimes in Australia’s seasonal tropics. J. Appl. Ecol. 2014, 51, 1406–1413. [Google Scholar] [CrossRef]
  42. Parr, C.L.; Andersen, A.N. Fire resilience of ant assemblages in long-unburnt savanna of northern Australia. Austral Ecol. 2008, 33, 830–838. [Google Scholar] [CrossRef]
  43. Andersen, A.N.; Muller, W.J. Arthropod responses to experimental fire regimes in an Australian tropical savannah: Ordinal-level analysis. Austral Ecol. 2000, 25, 199–209. [Google Scholar] [CrossRef]
  44. Wilson, E.O. Pheidole in the New World: A Dominant, Hyperdiverse Ant Genus; Harvard University Press: Cambridge, MA, USA, 2003; Volume 1. [Google Scholar]
  45. Vasconcelos, H.L.; Leite, M.F.; Vilhena, J.M.S.; Lima, A.P.; Magnusson, W.E. Ant diversity in an Amazonian savanna: Relationship with vegetation structure, disturbance by fire, and dominant ants. Austral Ecol. 2008, 33, 221–231. [Google Scholar] [CrossRef]
  46. Klimes, P.; Idigel, C.; Rimandai, M.; Fayle, T.M.; Janda, M.; Weiblen, G.D.; Novotny, V. Why are there more arboreal ant species in primary than in secondary tropical forests? J. Anim. Ecol. 2012, 81, 1103–1112. [Google Scholar] [CrossRef]
  47. Barrows, E.M. Nectar robbing and pollination of Lantana camara (Verbenaceae). Biotropica 1976, 8, 132–135. [Google Scholar] [CrossRef]
  48. Hossaert-McKey, M.; Orivel, J.; Labeyrie, E.; Pascal, L.; Delabie, J.; Dejean, A. Differential associations with ants of three cooccurring extrafloral nectary-bearing plants. Ecoscience 2001, 8, 325–335. [Google Scholar] [CrossRef]
  49. Blüthgen, N.; Fiedler, K. Competition for composition: Lessons from nectar-feeding ant communities. Ecology 2004, 85, 1479–1485. [Google Scholar] [CrossRef]
  50. Hoffmann, B.D. Responses of ant communities to experimental fire regimes on rangelands in the Victoria River District of the Northern Territory. Austral Ecol. 2003, 28, 182–195. [Google Scholar] [CrossRef]
Diversity 15 00996 g001
Figure 1. Individual-based rarefaction ant diversity curves showing (a) burning/mowing treatments and (b) season of treatments. Annual burn (AB), annual mow (AM), biennial burn (BB), triennial burn (TB), and control plots on Ukulinga Research Farm.
Figure 1. Individual-based rarefaction ant diversity curves showing (a) burning/mowing treatments and (b) season of treatments. Annual burn (AB), annual mow (AM), biennial burn (BB), triennial burn (TB), and control plots on Ukulinga Research Farm.
Diversity 15 00996 g001
Diversity 15 00996 g002
Figure 2. Box and whisker (95% confidence level) plots showing the effect of burning and mowing treatments and season on ant species richness on the Ukulinga research farm, South Africa. Coloured box plots indicate the season of treatments: annual burn (AB), annual mow (AM), biennial burn (BB), triennial burn (TB), and control (CON) plot treatments. The solid bar denotes median values, and the vertical extending lines denote minimum and maximum values.
Figure 2. Box and whisker (95% confidence level) plots showing the effect of burning and mowing treatments and season on ant species richness on the Ukulinga research farm, South Africa. Coloured box plots indicate the season of treatments: annual burn (AB), annual mow (AM), biennial burn (BB), triennial burn (TB), and control (CON) plot treatments. The solid bar denotes median values, and the vertical extending lines denote minimum and maximum values.
Diversity 15 00996 g002
Diversity 15 00996 g003
Figure 3. Box and whisker (95% confidence level) plot showing ant species richness across burnt, control, and mown treatment plots sampled on Ukulinga research farm, South Africa. The solid bar denotes median values, and the vertical extending lines denote minimum and maximum values.
Figure 3. Box and whisker (95% confidence level) plot showing ant species richness across burnt, control, and mown treatment plots sampled on Ukulinga research farm, South Africa. The solid bar denotes median values, and the vertical extending lines denote minimum and maximum values.
Diversity 15 00996 g003
Diversity 15 00996 g004
Figure 4. Box and whisker plots showing the occurrence of common ants in annual burn (AB), annual mow (AM), biennial burn (BB), triennial burn (TB), and control (CON) plot treatments.
Figure 4. Box and whisker plots showing the occurrence of common ants in annual burn (AB), annual mow (AM), biennial burn (BB), triennial burn (TB), and control (CON) plot treatments.
Diversity 15 00996 g004
Diversity 15 00996 g005
Figure 5. (a) Non-metric multidimensional scaling (NMDS) showing ant species composition in relation to treatment: annual burn (AB), annual mow (AM), biennial burn (BB), triennial burn (TB), and control (CON) treatments’ effects on ant assemblage sampled on Ukulinga research farm, Pietermaritzburg. (b) Non-metric multidimensional scaling (NMDS) showing ant species composition in relation to season of burning and mowing treatments (data pooled across burnt and mown plots). The two-dimensional plot with stress level = 0.2 was based on presence/absence. Annual burn (AB), annual mow (AM), biennial burn (BB), triennial burn (TB), and control (CON) plots.
Figure 5. (a) Non-metric multidimensional scaling (NMDS) showing ant species composition in relation to treatment: annual burn (AB), annual mow (AM), biennial burn (BB), triennial burn (TB), and control (CON) treatments’ effects on ant assemblage sampled on Ukulinga research farm, Pietermaritzburg. (b) Non-metric multidimensional scaling (NMDS) showing ant species composition in relation to season of burning and mowing treatments (data pooled across burnt and mown plots). The two-dimensional plot with stress level = 0.2 was based on presence/absence. Annual burn (AB), annual mow (AM), biennial burn (BB), triennial burn (TB), and control (CON) plots.
Diversity 15 00996 g005
Diversity 15 00996 g006
Figure 6. Functional group profile of ants between burning and mowing treatments: annual burn (AB), annual mow (AM), biennial burn (BB), triennial burn (TB), and control (CON). Stacked bars show a cumulative percentage of total species records from different functional groups: Cryptic Species (CS); General Myrmicinae (GM); Opportunists (OPP); Subordinate Camponotini (SC); Specialists Predators (SP); Tropical Climate Specialists (TCS).
Figure 6. Functional group profile of ants between burning and mowing treatments: annual burn (AB), annual mow (AM), biennial burn (BB), triennial burn (TB), and control (CON). Stacked bars show a cumulative percentage of total species records from different functional groups: Cryptic Species (CS); General Myrmicinae (GM); Opportunists (OPP); Subordinate Camponotini (SC); Specialists Predators (SP); Tropical Climate Specialists (TCS).
Diversity 15 00996 g006
Table 1. The results of GLM tests of the effect of burning and mowing treatments on the most common species (>50 abundance). The p-values highlighted in bold represent species with a significant response to the treatments.
Table 1. The results of GLM tests of the effect of burning and mowing treatments on the most common species (>50 abundance). The p-values highlighted in bold represent species with a significant response to the treatments.
Speciesp-Value
Acropyga UKZN_010.001
Crematogaster rectinota<0.001
Lepisiota capensis0.119
Monomorium UKZN_010.482
Pheidole UKZN_02 (megacephala gp.)<0.001
Pheidole UKZN_030.907
Solenopsis UKZN_010.969
Tetramorium UKZN_03 (setigerum gp.)0.003
Tetramorium UKZN_09 (simillimum gp.)0.876
Table 2. Indicator values (IndVal) of ant species for burnt, mown, and unburnt treatments on Ukulinga research farm. Species identified as indicators (IndVal > 70%) with significant p-values are highlighted in bold, with others being detector (IndVal < 70%) species.
Table 2. Indicator values (IndVal) of ant species for burnt, mown, and unburnt treatments on Ukulinga research farm. Species identified as indicators (IndVal > 70%) with significant p-values are highlighted in bold, with others being detector (IndVal < 70%) species.
Treatment Type and Species%IndValp-Value
Control
Tetramorium UKZN_19 (squaminode gp.)780.005
Camponotus UKZN_05 (maculatus gp.)770.005
Tetramorium nr grassi730.008
Tapinolepis UKZN_05690.016
Plagiolepis UKZN_01640.031
Camponotus UKZN_02 (cintellus gp.)610.017
Crematogaster rufigena530.048
Annual burn
Crematogaster rectinota400.009
Annual mow--
Biennial burn
Tetramorium UKZN_07 (setigerum gp.)590.037
Triennial burn
Tetramorium UKZN_09 (simillimum gp.)590.023
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Khoza, L.R.; Andersen, A.N.; Munyai, T.C. Effect of Long-Term Burning and Mowing Regimes on Ant Communities in a Mesic Grassland. Diversity 2023, 15, 996. https://doi.org/10.3390/d15090996

AMA Style

Khoza LR, Andersen AN, Munyai TC. Effect of Long-Term Burning and Mowing Regimes on Ant Communities in a Mesic Grassland. Diversity. 2023; 15(9):996. https://doi.org/10.3390/d15090996

Chicago/Turabian Style

Khoza, Lindiwe R., Alan N. Andersen, and Thinandavha C. Munyai. 2023. "Effect of Long-Term Burning and Mowing Regimes on Ant Communities in a Mesic Grassland" Diversity 15, no. 9: 996. https://doi.org/10.3390/d15090996

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop