Termite hills in Africa: Their characteristics and evolution

Small dome-shaped hills are recurrent and common landforms associated with plateau surfaces in the savanna woodland landscapes, both to the north and south of the Congo Basin. They may be occupied in part by termite colonies or be moribund. Previous ideas on the relationships between termite hills and termite mounds are discussed. The evolution of the hills is discussed in the light of evidence from variious parts of Zambia. It is concluded that the interaction of mound building by termites and mound destruction by rain beat and rain wash is complicated by plant colonisation, interference and use by animals, the incidence of fire and the activities of agricultural man. These are also factors which might explain the distribution of termite hills. The apparent fossilisation of the termite hills through the development of thicket vegetation is not regarded as necessarily dependent on climate change but could be the result of other changing ecosystem factors.     

美国市民农园生态植被景观营建及其启示

美国市民农园是一个值得借鉴的兼具生产、生态和生活等多功能的植被景观模式,本研究针对市民农园的生态服务功能,依据市民农园结构模式及经营群体的不同,随机选取了洛杉矶市14个市民农园,采用样地调查、半结构式访谈等方法,基于植被物种功能组合和乡土植物组成,定量化研究了城市植被物种多样性及其分布格局对种植者族裔背景及营建模式等影响因素的响应,进而评析对我国城市绿地建设和休闲农业的启示。本研究共计调查到439种植物,分属90科,242属,分析结果显示:市民农园是城市生态系统中重要的物种库,能维护较为丰富的乡土植物资源;其植物功能以食用植物为主,观赏植物、药用植物次之,这在保护族裔传统文化、区域乡土文化具有重要价值;其植被景观结构和功能受到族裔背景及营建模式等不同程度影响。研究证明,市民农园作为生态多样性和文化多样性的交汇景观,是实现城镇绿色基础建设和休闲农业发展的重要营建模式。以此为经验,我国在进行绿地规划和生态植被建设时要考虑不同利益相关者,尤其是关注外来者的生活习俗和选择偏好;同时也要注意监测外来物种,以防造成物种入侵,这对于建设文化强国背景下开展城镇生态植被建设和发展休闲农业具有启示意义。     

High performance liquid chromatography studies on the polysaccharides in the walls of the mounds of two species of termite in Senegal,Cubitermes oculatus and Macrotermes subhyalinus: their origin and contribution to structural stability

 The origin, nature and quantity of polysaccharides in the walls of the epigeal mounds of a species of soil-feeding termite, Cubitermes oculatus, and a fungus-growing termite, Macrotermes subhyalinus, found in Senegal, and of soil not considered to be under the influence of termites, were studied to obtain a clearer picture of the structural stability of these materials. The compounds were extractedand analysed by high performance liquid chromatography. We found that the walls of mounds made by soil-feeding species were very rich in sugars soluble in aqueous acid or hot water. Most of the sugars originated from cellulose and hemicellulose, and only a small proportion from microorganisms. There were also significant amounts of stachyose in the mound walls and in the reference soil. This sugar was probably formed by the surrounding vegetation, which was mainly leguminous crops. Comparison of the mineral and organic-mineral particle sizes of samples confirmed that the walls of soil-feeding termite mounds where there is the greatest redistribution of clay have the best aggregating capacity. The results therefore show that the polysaccharides in mound walls of soil-feeding termites are mostly of plant origin. Their influence on the stability of these structure is discussed. The walls of fungus-growing termite mounds contain little organic matter and hence low levels of polysaccharides, which are mainly of plant origin. Received: 19 July 1999     

Chemical,physical and micromorphological properties of termite mounds and adjacent soils along a toposequence in Zona da Mata,Minas Gerais State,Brazil

Little is known about the effects of neotropical mound-building termites in soil chemical and physical properties. The influence of soil termite activity on soil characteristics was studied by assessing chemical, physical and micromorphological properties of a toposequence of Latosols (Oxisols). Soil samples were collected from the walls and inner parts of termite mounds and also from adjacent soil. A high diversity of termite genera was found in the mounds along the toposequence, together with the inquiline termites and other soil-dwelling arthropods. Chemical analyses showed that pH and the contents of organic C and N, P, Ca and Mg were significantly higher in termite mounds compared with adjacent areas, with an inverse trend for Al content. Significant differences in pH and exchangeable Al were observed between soil and mound across the slopes. The mound density across the landscape was higher at the upper slope segment, followed by the hill top, middle slope and lower slope segments. Considering a lifespan of 30 years and dimensions of termite mounds found in the toposequence we conclude that the textural and chemical uniformity of Latosols may be increased, following the pedobiological turnover during mound building, with local rates varying from 2.1 to 7.5 m³ ha^− 1.     

THE COMPOSITION OF MOUNDS OF THE TERMITE MACROTERMES FALCIGER (GERSTACKER) ON SOIL DERIVED FROM GRANITE IN THREE RAINFALL ZONES OF RHODESIA

Thirty-eight termite mounds (about 1.6 m high and 7.6 m basal diameter) and the same number of adjacent soils were sampled in three rainfall zones: low (below 700 mm annual rainfall), medium (700 to 1000 mm annual rainfall), and high (above 1000 mm annual rainfall). Higher amounts of clay, silt, and fine sand, and lower amounts of coarse sand occurred in termite mounds than in adjacent soils of all rainfall zones. Extractable cations (Ca, Mg, and K), calcium carbonate, pH, electrical conductivity, and organic carbon were also higher in termite mounds than adjacent soils of all rainfall zones. Wide differences in extractable calcium between termite mounds and adjacent soils of low and medium rainfall zones indicated weak leaching of termite mounds; narrow differences in the high rainfall zone indicated strong leaching of the mounds. The ‘umbrella effect’ of termite mounds in shedding rainfall and retarding leaching is clearly displayed in the medium rainfall zone where high concentrations of extractable calcium in termite mounds and low concentrations in adjacent soils indicate weak and strong leaching respectively.     

THE USE OF MOUNDS OF THE TERMITE MACROTERMES FALCIGER (GERSTÄCKER) AS A SOIL AMENDMENT

Twelve termite mounds and adjacent Ah and Ap horizons were sampled at three sites near Salisbury, Rhodesia. The mass of termite mounds occupied by M. falciger at one site was estimated at 620 t/ha, and contained the following amounts of nutrients expressed as percentages of the amounts in mounds and Ap horizon combined: extractable Ca 95%, mineral N 81% extractable K 69%, and available P 69%. Pot experiments using perennial ryegrass gave higher dry matter yields from termite mounds than from the Ap and Ah horizons. Crop production could therefore be increased by mixing termite mounds with the soil.     

Nutrient storage in soils and nests of mound-building <Emphasis Type="Italic">Trinervitermes</Emphasis> termites in Central Burkina Faso: consequences for soil fertility

Nest structures of two termite species (Trinervitermes spp.) with epigeal (above-ground) mounds were analyzed to compare their nutrient status with that of adjacent soils. To take into account soil variability, the observations and samplings were made in three toposequences of different and representative West African savanna soils. The data showed the high degree of adaptation of these termite species to a large range of soil types and environments. Mounds of Trinervitermes geminatus and Trinervitermes trinervius, both grass-feeders, contained more clay, organic matter (OM), and exchangeable cations than the surrounding surface layer soil. The storage of OM and exchangeable cations was determined for T. geminatus nests and compared to the surrounding soil. Despite substantial nutrient storage in mounds, its total weight appeared low when compared to the nutrient storage in the surrounding 0–15 cm of soil surface layer. This illustrates how contradictory points of view on the use of termite mounds in agriculture need to be clarified using a classical approach that takes into account data by species; and this also evaluates the contribution of different termite mounds to nutrient fluxes and storage and the exact stocking rate of living mounds.     

湄公河流域生态系统服务与利益补偿机制

湄公河流域是中国"一带一路"沿线的重要门户,核算流域各国的生态系统服务价值(Ecosystem Service Value,ESV)与利益补偿量,对建立各国资源利用与经济补偿的联动关系、促进流域协调发展具有重要意义。基于生态足迹理论,对湄公河流域1995—2015年的ESV和生态盈余(或赤字)状况进行了动态评估,结合流域各国的实际经济发展水平对生态补偿优先级进行量化分析,初步建立了各国ESV与实际生态补偿量的转化关系,并对"生态消费型"国家在现状年(2015年)的实际生态补偿量进行了确定。结果表明:1)湄公河流域ESV由1995年的1 289.76亿美元下降至2015年的1 259.21亿美元,各国ESV从大到小依次为:泰国、老挝、柬埔寨、越南、缅甸;各国林地ESV的比例最大(60.0%),水域和湿地ESV比例的增幅最快,近20 a增加了4.5%。2)1995-2015年间,流域境内的缅甸、老挝两国为生态盈余状态,其他3国为生态赤字状态,且赤字水平呈逐年加重趋势,其中泰国、越南两国对全流域生态足迹(Ecological Footprint,EF)的贡献比例高达80.1%。3)流域上游的缅甸、老挝两国为"生态输出型"国家,下游的3个国家为"生态消费型"国家,其中泰国、越南两国经济发展水平较好且生态补偿优先级系数(Ecological Compensation Priority Sequence,ECPS)更低(分别为0.05和0.09),均低于其他3个湄公河流域国家(缅甸:2.67,老挝:1.16,柬埔寨:0.55),应率先进行生态支付。4)结合流域各国的实际经济发展水平,初步确定下游"生态消费型"国家应支付实际生态补偿合计680.63亿美元,泰国、越南和柬埔寨分别支付507.73、167.61和5.29亿美元。该研究结果可为湄公河流域资源管理和生态补偿政策的建立提供理论支撑,并为其他跨境流域相关的研究提供借鉴与参考。     

The spatial extent of termite influences on herbivore browsing in an African savanna

Termite mounds form islands of fertility in savanna landscapes and create foraging hotspots for herbivores, but the magnitude and spatial extent of these influences is unknown. We mapped terrain, termite mound and woody vegetation three-dimensional (3-D) structure at 56 cm resolution across a large-scale (254 ha), long-term (34 years) herbivore exclusion experiment in the Kruger National Park, with the Carnegie Airborne Observatory (CAO). We compared vegetation 3-D structure in areas protected from herbivores with those accessible to herbivores, both on termite mounds and in the landscape matrix between termite mounds. Termite mound density was 1.1 ha⁻¹ across the study area and mound size did not differ between protected and accessible areas. Woody vegetation canopy cover was ∼100% greater on protected than accessible mounds, but was only ∼20% greater in the protected inter-mound matrix when compared to the accessible matrix. Woody canopy height class distributions differed significantly between protected and accessible areas, with the tallest vegetation (>10 m) occurring on protected termite mounds. The impacts of herbivore browsing were evident at distances of up to 20 m from termite mound centres. Spatial analysis of mound distribution revealed that the sphere of termite mound influence constitutes ∼20% of the total landscape. Termite influences on herbivore browsing operate at scales much larger than the spatial extent of their mound building activities.     

Use of RAPD markers for the study of microbial community similarity from termite mounds and tropical soils

In this study, we test the use of the RAPD (Random Amplified Polymorphic DNA) molecular markers as a way to estimate the similarity of the microbial communities in various termite mounds and soils. In tropical ecosystems, termite activities induce changes in the chemical and physical properties of soil. The question then arises as to whether or not termites affect the presence of natural microbial communities. Successful 16S rDNA amplifications provided evidence of the occurrence of bacterial DNA in termite constructions including both soil feeder and fungus grower materials. A phenetic dendrogram using the similarity distance calculated from pairwise data including 88 polymorphic RAPD markers was reconstructed and bootstrap scores mapped. The microbial communities of the mounds of the four soil-feeding termites were clustered in the same clade, while those of the mounds of the fungus-growing species were distinct like those of control soils. Microbial changes in nests result from termite building behavior, depending on whether they include feces in their constructions for soil-feeders or use saliva as particle cement for fungus-growers. It is argued that RAPDs are useful markers to detect differences in microbial community structure not only between termitaries and control soils but also between mounds of soil-feeders.     

The importance of the gravel excavation industry for the conservation of grassland butterflies

Conservation biology often relies on the protection of (semi)natural habitat remnants. However, the ever increasing human population is taking over natural resources and habitats. Here, contrary to most other studies, we ask how human-associated severe changes in the environment can be used to enrich local biodiversity. We tested if industrial activity (gravel excavation) leads to the creation of habitats that support grassland butterflies and how these areas add to the richness of local species when compared to typical semi-natural habitats (grasslands). We also identified key factors affecting the richness, abundance, diversity and commonness of butterfly species to provide practical recommendations. Species richness, diversity index and the occurrence of rare species were higher in gravel-pit shores than in grasslands. The richness of butterfly species and their abundance were positively affected by the richness of plant species, shrub density and age of the gravel-pit but negatively by the cover of water reservoirs in the surrounding area and the isolation of gravel-pits from grasslands. Butterfly diversity was positively influenced by the richness of plant species and proximity of human settlement but negatively by area of the shore and isolation. Our study is the first one to show the high value of gravel-pits for the conservation of butterflies. We recommend the inclusion of gravel-pits in a system of ecological networks and management of their surroundings to improve the colonization rate of rare species. We suggests that directing interest to the possible positive effects of industrial development on biodiversity may support conservation efforts.     

Spatial congruence between biodiversity and ecosystem services in South Africa

Ecosystems services sustain humans all over the world. The unsustainable use of ecosystem services around the world has led to widespread degradation which now threatens human health and livelihoods. Although the maintenance of ecosystem services is often used to justify biodiversity conservation actions, it is still unclear how ecosystem services relate to different aspects of biodiversity and to what extent the conservation of biodiversity will ensure the provision of services. The aim of this study was to find out whether biodiversity priorities, biomes, species richness and vegetation diversity hotspots co-occur in space with ecosystem services. The distribution of the ranges and hotspots of five ecosystem services (surface water supply, water flow regulation, carbon storage, soil accumulation, and soil retention) was assessed in South African biomes. Coincidence, overlap, and correlation analyses were used to assess spatial congruence between ecosystem services and species richness (plants and animals) and vegetation diversity hotspots. The grassland and savanna biomes contained significant amounts of all five ecosystem services. There was moderate overlap and a generally positive but low correlation between ecosystem services hotspots and species richness and vegetation diversity hotspots. Species richness was mostly higher in the hotspots of water flow regulation and soil accumulation than would be expected by chance. The water services showed varying levels of congruence with species richness hotspots and vegetation diversity hotspot. These results indicate that actions taken to conserve biodiversity in South Africa will also protect certain ecosystem services and ecosystem services can be used to strengthen biodiversity conservation in some instances.     

The composition of termite (macrotermes spp.) mounds on soil derived from basic rock in three rainfall zones of Rhodesia

Termite mounds and adjacent soils were sampled in three rainfall zones: < 700 mm, 700–1000 mm and > 1000 mm per annum. Electrical conductivity, and extractable calcium, magnesium and potassium are significantly higher in termite mounds than adjacent soils in all rainfall zones.Values of pH, electrical conductivity and extractable calcium show large differences between termite mounds and adjacent soils in the low- and medium-rainfall zones, and small differences in the high-rainfall zone. Differences in the absolute concentration of extractable calcium (extract. Ca mounds - extract. Ca soils) between termite mounds of the three rainfall zones were probably caused mainly by leaching.     

东北平原典型玉米种植区农业景观植物多样性研究——以昌图县为例

非耕作生境是农业景观中的重要组成部分,为生物提供食物和栖息地,对生物多样性保护具有重要意义。本文以辽宁省昌图县为例,选取了20个非耕作生境比例为0~50%的网格(1 km?1 km)为样区,采用典型样地法对调查区域内农业景观中的林地、田间路、草地、沟渠、果园5类主要非耕作生境中的植物群落进行调查,探讨不同非耕作生境类型和比例中植物多样性及其与景观异质性之间的关系。研究结果表明,随着非耕作生境比例增加,植物物种多样性和均匀度先增加后减小,在20%~30%时达到峰值;非耕作生境比例在0~40%范围内时,植物物种丰富度同样呈现先增加后减小,且在20%~30%时达到峰值;非耕作生境比例高于40%时,植物物种丰富度再次出现峰值且高于20%~30%。随着非耕作生境比例的增加,农业景观香浓多样性、香浓均匀度指数和景观斑块形状复杂程度逐渐增加,蔓延度恰好相反。不同生境中重要值最高的均为禾本科植物,但植物种不同;优势种优势度为果园沟渠草地田间路林地。果园、草地和沟渠的物种多样性和均匀度指数显著高于林地和田间路,丰富度指数为草地林地沟渠果园田间路,且草地、果园和田间路的不同调查区域间植物群落指数存在较大的变异性。草地、果园、沟渠、田间路和林地中景观异质性与物种多样性相关性顺次降低。研究结论表明,东北平原典型玉米种植区农业景观中,最适宜非耕作生境比例为20%~30%;非耕作生境中林地、沟渠对物种多样性维持、湿生植物多样性保护具有积极作用;不同生境干扰类型和方式不同,景观异质性与植物物种多样性相关性程度也不同。在今后农业景观生物多样性保护中应综合考虑非耕作生境的类型和比例,干扰的类型和方式等多种因素对生物多样性、生态服务及农业产量的影响。     

Effects of vineyard management on biodiversity at three trophic levels

In annual crops, where disturbance intensities are generally high, numerous investigations demonstrated beneficial effects of organic and other extensive farming practices on biodiversity. It is however unclear if organic farming has the same beneficial effect in perennial crops (e.g. vineyards) because of a generally reduced background disturbance level. Moreover, the impact of farming practices on biodiversity may differ between trophic levels. We tested the effect of farming practices differing in disturbance intensity on the abundance, species richness and community composition of three trophic levels (plants, grasshoppers and spiders) in Swiss vineyards. Organic and conventional vineyards were compared, and within the latter different options of weed control (mowing vs. mulching) and pest management (hand spraying vs. helicopter spraying) were investigated. In contrast to findings in annual crops, organic farming promoted neither diversity nor abundance at any trophic level. Grasshopper diversity was even significantly lower in organic compared to conventional vineyards. Weed control as well as pest management differed in their effects, depending on the trophic level. Within conventionally managed vineyards, spider and grasshopper diversity were enhanced by mulching, while plants benefited from the lower disturbance of mowing. The greater disturbance of fungicide spraying by hand than by helicopter was disadvantageous for grasshoppers, but did not affect spiders and plants. Thus, different taxa respond differently not only to an increase in disturbance but also to different types of disturbance and local site conditions. We conclude that disturbance in organically farmed vineyards appears to be too low to be beneficial for biodiversity.     

Impacts of termites on selected soil physicochemical characteristics in the highlands of Southwest Ethiopia

Termites are reported to improve soil physicochemical properties thereby enhance soil fertility of their mound and foraging areas. Empirical study pertaining to these effects is missing in Southwest Ethiopia. For this study, soil samples affected by termite activities were collected at 1 m interval within 0–3 m distance from the base of six termite mounds on gently sloping and sloping land and analyzed for physicochemical parameters. The result of the analysis depicted that soil bulk density (1.38–1.15 g cm^?3) and moisture content (21.1–9.9%) decreased with increased distance from the mound base. While clay content decreased with increased distance from the mound base from72.0% to 45.5%, sand and silt contents increased from 8.0% to 21.3% and 19.3% to 28.5%, respectively. PH (6.23), organic carbon (3.85%), total nitrogen (0.4%), cation exchange capacity CEC (30.43 cmol kg^?1), exchangeable Ca (13.73 cmol kg^?1), Mg (3.15 cmol kg^?1), and PBS (56.8%) were higher on termite mounds. While, electrical conductivity (0.03 dS m^?1–0.06 dS m^?1), exchangeable K (0.52–0.93 cmol kg^?1) and Na (0.02–0.03 cmol kg^?1) showed increasing trend with the distance from the mound base. Our results indicated that termite mounds are important sinks of organic matter and mineral nutrients, and hence contribute to the enhancement of soil fertility. Thus, for subsistent farmers the uses of termite mounds as a fertilizer present an opportunity to improve agricultural production.     

稻鸭共作对稻田水体底栖动物生物多样性的影响

在水稻不同生育时期对稻鸭共作稻田和常规稻田的土壤取样,研究不同稻田生态系统水体底栖动物的生物多样性。结果表明：与常规稻田相比,稻鸭共作使水体底栖动物的种类数减少。水稻生育前期,稻鸭共作使底栖动物的个体总数减少较大,后期与常规稻田差异较小。水稻各生育时期常规稻田和稻鸭共作稻田底栖动物的Shannon-Wiener多样性指数、Simpson多样性指数和Pielou均匀度指数变化趋势相似,均为水稻生育前期稻鸭共作稻田的生物多样性指数和均匀度指数高于常规稻田,而后期低于常规稻田。研究结果为规范稻鸭共作稻田水分管理和稻鸭共作技术提供理论指导,促进稻鸭共作技术的推广和应用。     

Management strategies to increase stand structural diversity and enhance biodiversity in coastal rainforests of Alaska

Coastal rainforests of southeast Alaska have relatively simple species composition but complex structures with high diversity of tree ages, sizes and forest canopy layers, and an abundant understory plant community. Wildlife and fisheries resources also play an important role in the ecological functioning of forest and aquatic systems. Clearcutting has greatly altered these forest ecosystems with significant decreases in structural diversity of forest stands and greatly reduced wildlife habitat. This paper synthesizes information on management options in older forests that have never been actively managed, and in younger forests to increase diversity of stand structures and their associated effects on biodiversity. Light to moderate levels of partial cutting in old-growth forests can maintain the original diversity of overstory stand structures and understory plant communities. In younger forests that develop after clearcutting, mixed alder-conifer stands provide more heterogeneous structures and significantly higher understory biomass than in pure conifer forests. Research has shown that red alder increases diversity and abundance of understory plants, and provides forage for deer and small mammals. Results also show a clear linkage between alder and improved invertebrate diversity in aquatic systems. A combination of light partial cutting in older forests along with inclusion of red alder in conifer-dominated forests could provide the greatest amount of diversity and maintain the complex stand structures that are an important component of these forest ecosystems.     

Effects of the annual invasive plant Impatiens glandulifera on the Collembola and Acari communities in a deciduous forest

Invasive plants can disturb interactions between soil organisms and native plants and thereby alter ecosystem functions and/or reduce local biodiversity. Collembola and Acari are the most abundant microarthropods in the leaf litter and soil playing a key role in the decomposition of organic material and nutrient cycling. We designed a field experiment to examine the potential effects of the annual invasive plant Impatiens glandulifera on species diversity, abundance and community composition of Collembola and Acari in leaf litter and soil in a deciduous forest in Switzerland. Leaf litter and soil samples were obtained from plots invaded by I. glandulifera since 6 years, from plots in which the invasive plant had been removed for 4 years and from plots which were not yet colonized by the invasive plant. The 45 leaf litter and soil samples were equally distributed over three forest areas, which were differently affected by a wind throw 12 years prior to sampling representing a natural gradient of disturbance. Collembola species richness and abundance in the leaf litter and soil samples were not affected by the presence of the invasive plant. However, the species composition of Collembola was altered in plots with I. glandulifera. The abundance of leaf-litter dwelling Acari was increased in invaded plots compared to the two other plot types. Furthermore, the presence of the invasive plant shifted the composition of Acari individuals belonging to different groups. Our field experiment demonstrates that an annual invasive plant can affect microarthropods which are important for nutrient cycling in various ecosystems.     

Different microhabitats affect soil macroinvertebrate assemblages in a Mediterranean arid ecosystem

Spatio-temporal variability is a key factor in conservation, management and restoration of ecosystems. Spatial heterogeneity is caused in many cases by organisms that are able to modify their environments. This is especially relevant in arid systems, where organisms such as shrubs and ants create patches of high nutrient availability (fertile islands) surrounded by a low-nutrient matrix. Although variations in structure and physiology among shrubs provoke differences in their effects as fertile islands, whether different microhabitats vary in their influence on animal communities is poorly known. The principal aim of our study is to analyse the effects of different shrub species and Messor harvester ant-nest mounds on the structure of soil macroarthropod assemblages in a strongly seasonal desert location of SE Spain. Shrub microhabitats and ant-nest mounds maintained higher species density, abundance and biomass of soil macroinvertebrates than the surrounding soil matrix. The different microhabitats differed in taxonomic and trophic composition, abundance, and biomass of soil macroinvertebrates, at both litter and belowground levels. Also, variations of invertebrate abundance among microhabitats changed throughout sampling periods. Thus the spatio-temporal heterogeneity of the study site affected the distribution and dynamics of the macroinvertebrate community. The above results indicate that the spatio-temporal mosaic created by microhabitat and seasonal variations on macroinvertebrate assemblages is a relevant issue to be considered in conservation, sustainable management and environmental restoration in heterogeneous arid systems to preserve their biodiversity and ecosystem functioning.