Canopy arthropod communities on Mexican oaks at sites with different disturbance regimes

We examined the effects of forest disturbance and fragmentation on diversity and composition of canopy arthropod fauna in six oak species in central Mexico. Canopy fogging of 54 trees during rainy and dry seasons was conducted on three temperate forests with different levels of disturbance and habitat fragmentation. In total, we found 831 morphospecies belonging to 20 arthropod orders. Diversity of arthropods was higher in the rainy season. Acari, Hymenoptera and Diptera orders dominated during the dry season, and Acari and Collembola during the rainy season. Oak species distributed in sites with lower disturbance had significantly higher arthropod diversity than those distributed in disturbed and fragmented sites. Mean density of arthropod fauna ranged from 47.0 individuals m⁻² in the dry season to 375.5 m⁻² in the rainy season. Forest disturbance and fragmentation reduced the number of arthropod morphospecies and modified the relative abundance of arthropods at order level.     

基于干、湿筛法下滇中森林土壤团聚体酶活性特征对氮沉降的响应

研究森林土壤团聚体酶活性对氮沉降的响应差异以及团聚体酶活性的影响因素，以滇中亚高山云南松林和华山松林为研究对象，于2020年6月至2021年5月通过野外模拟氮沉降试验，设置对照[CK,0 g/(m²·a)N]、低氮[LN,10 g/(m²·a)N]、中氮[MN,20 g/(m²·a)N]、高氮[HN,25 g/(m²·a)N],分别采集旱季(2021年2月)和雨季(2020年8月)的土壤样品，分析土壤团聚体中脲酶(Ure)、蔗糖酶(Inv)和酸性磷酸酶(AP)的变化特征，以及与环境因子的交互作用，阐明不同筛分方式下土壤团聚体酶活性对氮沉降的响应特征。结果表明：(1)氮沉降对2种林分下土壤团聚体的分布未造成显著影响，而不同筛分方式则影响显著；不同氮沉降水平下，土壤团聚体中3种酶活性均表现出LN促进，MN与HN抑制；(2)与干筛法相比，湿筛法下土壤团聚体中酶活性均有显著下降，Inv和Ure的团聚体酶活性的降幅均在20%以上，AP的降幅可达57.55%;(3)土壤干筛、湿筛团聚体酶活性的几何平均数(GMe...     

Deforestation effects on soil degradation and rehabilitation in western Nigeria. IV. Hydrology and water quality

Hydrological and water-quality measurements were made on a 44·3 ha watershed under forest cover and following deforestation and conversion to an agricultural land-use. Under secondary tropical rainforest, water yield ranged from 2·2 per cent to 3·1 per cent of annual rainfall. Deforestation of 7 per cent of the watershed area increased water yield to 7·0 per cent of annual rainfall. Baseflow increased with deforestation, and increased progressively with time after deforestation. It was 5·1 per cent of annual rainfall in 1979, 15·1 per cent in 1980, 16·4 per cent in 1981 and 17·9 per cent in 1982. In comparison, surface flow was 4·5 per cent in 1979 and 6·2 per cent in 1980, but decreased to 2·3 per cent in 1981 and 2·4 per cent in 1982. Total water yield following deforestation and conversion to agricultural land-use ranged from 9·6 per cent to 21·3 per cent of the annual rainfall received. The dry season flow decreased with time as the dry season progressed, but increased over the years following deforestation. Surface runoff during the rainy season depended on ground cover and soil quality. The extent and severity of soil degradation affected the dynamics of surface flow. Because of actively growing crops, plant nutrient concentrations in surface runoff were low. Forested lysimeters had higher seepage losses than cropped lysimeters, and the water-use efficiency was 1·9–3·6 kg ha⁻¹ mm⁻¹ for cowpeas compared with 6·1–11·0 kg ha⁻¹ mm⁻¹ for maize. The delivery ratio was high immediately after deforestation and decreased to a steady value of about 3·2 per cent within 7 years. The data show five distinct phases of soil degradation in relation to generation of surface runoff. © 1997 John Wiley & Sons, Ltd.     

Atmospheric Total Suspended Particulate Trace Element Identification by XRF at Ilha Grande, State of Rio De Janeiro, Brazil

Phosphorus, manganese, sulfur (S), lead, and strontium of atmospheric total suspended particulate matter, sampled during the rainy season and the dry season 2002 at the Ilha Grande Island (Rio de Janeiro State, Brazil) have been analyzed by XRF techniques. The results showed total mean concentrations of 27?±?16 ng P m^-3, 11?±?7 ng Mn m^-3, 159?±?126 ng S m^-3, 4.3?±?2.6 ng Pb m^-3, and 208?±?148 ng Sr m^-3. Generally, there is no clear influence of the two different climatic periods on the concentrations of most analyzed trace elements, with exception of sulfur the mean concentration of which, during the dry season, is about 60% higher than during the rainy season. This is probably due to biomass burning, a common practice in the Brazilian Southeast and Amazon region and/or to the presence of marine aerosols. The linear correlation coefficients strongly suggest the same source for P, Pb, and Mn. Some Pb, Mn, and P concentrations are in the range of typical values of urban areas. Potential sources of such elements are the urban and industrial emissions from the States of Rio de Janeiro and/or São Paulo.     

Woodland structure,destruction and conservation in the Copperbelt area of Zambia

Between 1937 and 1983 a total of 391 400 ha of woodland, representing 51% of the 768 900 ha in the Zambia Copperbelt, had been deforested for industrial and household woodfuel. This has occurred in spite of a forest reservation programme that increased the area in forest reserves from 31 707 ha in 1942 to 252 715 ha in 1965. Between 1965 and 1980 the reserved forests were reduced to 246 930 ha and since then the area has remained static. The rapidly growing demand for charcoal by the increasing urban population, and the growing problem of acid dust and rain pollution from copper smelters, pose serious threats to forest conservation in this industrial region of Zambia. Current forest conservation is restricted to the establishment of exotic forest plantations and recently deforested areas are left to regenerate naturally.Forest destruction and conservation in the Copperbelt area were studied and the structure of old-growth and coppice woodland stands at 9 and 14 sites, respectively, investigated during 1982–1984. The Copperbelt vegetation is dominated by Brachystegia-Julbernardia woodland. Mean species diversity of 24·40·1 ha⁻¹ in coppice stands was higher than that of 18·9 found in old-growth stands. Stem density in coppice was 3·3 times that observed in old-growth woodlands. The majority of species (over 50%) in both old-growth and coppice were represented by less than 11 stems per sampling plot. Mean basal area at breast height in coppice aged 19–23 years was 14·33 m², which was 95% of the mean basal area of 15·15 m² found in old-growth woodlands.     

Nakdong estuary barrage and reclamation project: Preliminary results of the botanical,macrozoobenthic and ornithological studies

The Nakdong Estuary Barrage and Reclamation Project has been investigated by studies on the vegetation, macrozoobenthos and birds in the Nakdong river delta, Republic of Korea. This study deals with the preliminary results, obtained during October to November 1983, while the environmental impacts of the barrage were being discussed.The total biomass of Scirpus triqueter, the estuary's most important foodplant for waterfowl (mainly for swans), was assessed at approximately 38·3 tonnes dry wt. Of this amount only the roots and rhizomes (9·6 tonnes dry wt) are expected to be consumed by birds. Aquatic weeds in the nearby fresh Jukrim branch provided another food source (5·8 tonnes dry wt).The wintering waterfowl also used other feeding areas such as farmland and freshwater impoundments—almost all herbivorous birds participated in nightly feeding migrations.At 12 stations, spread over 20·5 km² of intertidal flats of the estuary, a total of 40 macrozoobenthic species were found. Crustaceans dominated with 19 species, while molluscs and polychaetes were represented by 11 and 10 species, respectively. For all stations together an average biomass of 14·6 g ash-free dry wt (ADW) m⁻² (range 3·1–51·9 g) was calculated, dominated by molluscs with 9·5 g, while the share of crustaceans and polychaetes was only 2·9 g and 2·2 g, respectively. In terms of weight, the bivalve Corbicula japonica was dominant with an average of 4·4 g ADW m⁻².During three censuses 10 000 waders and 25 000 to 30 000 waterfowl were counted. Among them were two species not recorded before in Korea: the ruff and the canvasback. Of all nonpasserines the wigeon (with a peak of 6800) and the dunlin (with a peak of 9100) were most numerous, while the ducks proved to be the most dominant (64%) group of birds.In the beginning of October the wader density in the estuary amounted to 5·2 birds ha⁻¹ intertidal area exposed at low tide.     

A survey of population and habitat of the barbary macaque macaca sylvanus L. in North Morocco

A three-month survey, including systematic censusing of Barbary macaque populations in the Djebala region of North West Morocco, was conducted in 1980. Primary objectives included the assessment of the status of natural populations, and of habitat and anthropogenic factors affecting population sizes and densities. Data were collected on group size, composition and stability of monkey groups within four habitat types (coniferous forests, mixed oak forests, low and high matorral) in five main localities where the monkey was known to exist.Estimated monkey densities and population sizes varied between areas and habitats from 0·37 to 3·38 animals km^?2 and from 12 to 254 monkeys respectively. The highest figures were obtained for the fir forest surrounding Djevel Lakraa. A total maximum population of 383 was estimated for the entire study area. This figure indicates that the species is more abundant than had been suspected before. However, the monkey populations in the Djebala are very depressed when compared with those on the Middle Atlas and Algeria. Unless conservation measures are implemented immediately both to protect and to manage the most suitable habitats, the Barbary macaque in the Rif risks extinction in the near future. Two areas of forest, on Djebel Bouhassim (cork and Portuguese oak) and on Djebel Lakraa (fir) are recommended as Nature Reserves.     

Abundance of soil mites under four agroforestry tree species with contrasting litter quality

 Populations of soil-dwelling mites were monitored in monoculture plots of four agroforestry tree species, Gliricidia sepium, Leucaena leucocephala, Dactyladenia barteri and Treculia africana, and compared to those in grass and secondary forest plots in the dry season (December 1993 to January 1994) and in the wet season (April to June 1994) in southwest Nigeria. Mite populations were very low in all plots during the dry season (500–3000 m^–2), compared to those during the wet season (10 000–30 000 m^–2). The highest mite population was observed in Gliricidia plots (3 044 m^–2) for the dry season and Leucaena plots (30 240 m^–2) for the wet season. Mite genera that were dominant in all the experimental plots were Annectacarus, Haplozetes, Machadobelba, Scheloribates and members of the Galumnidae, Dermanyssidae and Parasitidae. The community structure of mites was similar in the soil for Treculia and Gliricidia plots and for Leucaena and Dactyladenia plots. There were more taxonomic groups of mites under Leucaena than in the other agroforestry plots. Based on the density, diversity and complexity of the mite communities, Leucaena was considered to be better than other agroforestry species in encouraging the growth of mite populations. Received: 28 April 1998     

Seasonal and Diurnal Concentrations of Ambient Formaldehyde and Acetaldehyde in Bangkok

The concentration level of carbonyl compounds in Bangkok ambient air were measured in five roadside sites and five residential sites during July 2007 to April 2008. About 250 samples were collected and ten carbonyls were identified. Formaldehyde and acetaldehyde were the most abundant carbonyl compounds found in Bangkok ambient air. The ambient concentration of formaldehyde at the roadside areas in Bangkok during July 2007 to April 2008 ranged from 5.14 to 17.2 ??g/m³ (average 11.53 ??g/m³) while, the ambient concentrations of formaldehyde in residential areas in Bangkok during the same period ranged from 3.06 to 19.9 ??g/m³ (average 9.65 ??g/m³). The concentrations of acetaldehyde in roadside areas ranged from 1.59 to 7.95 ??g/m³ (average 3.51 ??g/m³) while at the residential areas the concentrations of acetaldehyde during the same period ranged from 1.07 to 8.05 ??g/m³ (average 3.11 ??g/m³). Other compounds showed low concentration. The concentrations of formaldehyde and acetaldehyde were low during the rainy season due to rain washout since these compounds are water soluble. The concentrations were high during the cold season due to stable conditions during these months. The concentrations slightly decreased during the summer due to photochemical reactions and photolysis under extreme temperature. Formaldehyde and acetaldehyde showed good correlation during 17:00 P.M. to 05:00 A.M. due to absence of solar radiation that may enhance photochemical reactions and mobile sources may be the sources of emission in the environment. It was also found that the concentrations of formaldehyde and acetaldehyde were low during the night time.     

不同林地类型土壤水库蓄水特性研究

研究不同林地类型土壤水库的蓄水特性,以期加深对森林土壤水库削洪补枯机理的认识。以裸露地为对照,木荷林地、杉木林地和封山育林地为研究对象,对它们土壤水库的蓄水功能及其动态变化进行研究。结果表明:木荷林地、杉木林地、封山育林地和对照土壤水库的年均蓄水量分别为381.1,368.7,336.9和243.6mm,分别占各自总库容的75.62%,78.18%,74.62%和59.57%。不同季节中不同林地类型土壤水库的月均蓄水量大小顺序均为多雨期>雨量中等期>少雨期,木荷林地、杉木林地和封山育林地土壤水库多雨期的月均蓄水量分别比对照的多124.8,121.9和85.0mm,少雨期的月均蓄水量也分别比对照的多141.0,129.2和91.0mm。     

Phytosociology of Sinharaja—A contribution to rain forest conservation in Sri Lanka

The structure and floristic composition of the vegetation over 30 cm girth at breast height (gbh) in five relatively undisturbed forest sites, each 5 ha in extent, in the Sinharaja International Man and Biosphere rain forest reserve investigated reveal a similarity in their (a) mean density of individuals (594–769) per ha, (b) basal area (36·0–41·6 m²) per ha and vertical distribution of individuals. The 17 427 individuals enumerated were identified into 211 species, 119 genera and 43 families. Contribution of endemic species to density, basal area and floristic richness in terms of total species complement ranged between 75–93%, 87–93% and 64–75% respectively.Clusiaceae [Improtance Value Index (IVI) = 27·3–78·1] and Dipterocarpaceae (IVI = 39·9–50·3) were the two most dominant families in this forest. Based on height attained by mature individuals of a species, 59 canopy, 49 subcanopy and 103 understorey tree species were discerned. In all except sample site 2, Garcinia hermonii (Clusiaceae) followed by Xylopia championii (Annonaceae) dominated the understorey tree stratum, but in the subcanopy and canopy the dominants were more diverse.Of the 211 species recorded, 40% had population densities of 10 individuals or less per 25 ha and 43% were restricted either to one or two sites sampled. These species, particularly the endemics among them, may be considered vulnerable species and further encroachments into the reserve will jeopardise their survival. Even for those endemics once widespread in the lowland wet zone of the island, Sinharaja has now become the last refugium as most of their habitats have been modified, leaving a mere 9% of the wet zone land area under natural forest cover. This too, is fragmented and inadequately protected. Conserving Sinharaja in its entirety is therefore all the more important and is highlighted in this phytosociological survey.     

The status of the forest elephant Loxodonta africana cyclotis,Matschie, 1900, in the Gola Forest reserves,Sierra Leone

From March until December 1982 a survey of elephants Loxodonta africana cyclotis in the Gold Forest complex, Sierra Leone, was carried out. The aim of the study was to deterine the density and the home ranges of the elephant population in the Gola Forest Reserves. There are two separate populations, in Gola North and in Gola East. In Gola North the mean density was estimated to be 0·1 km⁻², in Gola East 0·27 km⁻². The size of the home range in Gola North was 8500 ha in the dry season and 21 000 ha in the wet season; the home range in Gola East covered 13 000 ha in the dry season and 29 000 ha in the wet season. The results are compared with those of other forest elephant areas in West Africa.     

Fish Diet and Mercury Exposure in a Riparian Amazonian Population

The incorporation of mercury into the food chain and its assimilation by humans is a universally recognized potential health hazard. Studies carried out in the Amazon Basin have shown that mercury (Hg) is present in fish and in humans, however, the relation between fish diet and human exposure has received limited attention in this region. The present study focused on a small village, Brasília Legal (3°59′00″S, 55°30′00″W), situated on the banks of the Rio Tapajós. A total of 181 fish (40 species) were captured in March, 1995 and analysed for Hg concentration. Of these, 132 fish were among species consumed by the population during the rainy season (mid-November to mid-May) and the dry season (mid-May to mid-November). Wide intra- and inter-species variations in Hg concentrations were observed. Thirty four fish (25.8% of the consumed species) had levels above 0.5 μg/g Hg fresh weight; all were among the piscivorous and omnivorous species. Hair Hg concentrations (HHg), showed that villagers with a high fish diet (n=31; median HHg=16.1 μg/g) and mixed fish diet (n=36; median HHg=14.8 μg/g) had significantly higher HHg concentrations compared to the low fish diet group (n=29; mean HHg=7.8 μg/g). Time series function of HHg measurements, made for 26 persons with over 24 cm of hair, revealed sinusoidal variations, with peaks during the rainy season and troughs during the low water period, paralleling the seasonal shift in dietary habits. Piscivorous and omnivorous fish species, with higher mercury levels, are the main component of the fish diet during the rainy season, while herbivorous fish species predominate during the dry season. Preventive actions should take into account the risk to human health, particularly for fetal and neonatal development, the importance of fish in the riparian diet, the wide intra- and inter-species variations in mercury content and seasonal fluctuations in diet.     

干热河谷不同土地利用类型坡面土壤水分时空变异

为探究干热河谷区不同土地利用类型坡面土壤水分的时空变化规律,以元谋干热河谷老城小流域水土保持综合治理示范区内的银合欢人工林地、扭黄茅草丛地和坡耕地为研究对象,采用经典统计学和地统计学克里格插值相结合的分析方法,对3种土地类型坡面土壤水分的时间和空间异质性进行研究。结果表明:元谋干热河谷区土壤含水量较低(林地旱季7.56%,雨季12.80%;草地旱季8.05%,雨季12.66%;坡耕地旱季19.37%,雨季22.95%),雨季显著大于旱季。旱、雨季均表现为坡耕地草地林地,呈中等至强度变异(0.14~0.72之间);不同土地利用类型下各层土壤水分的自相关系数均由正向负转化的相同趋势,但拐点有所不同,且雨季大于旱季;不同土地利用类型下旱、雨季土壤水分的最佳拟合模型林地与草地相同(林地与草地旱雨季均为球状模型,坡耕地旱雨季为指数模型),均呈中等或强等空间相关性(0.05~0.39之间),且旱季大于雨季;同一土地类型下旱、雨季不同土层的土壤水分空间分布相似,不同土地利用类型下相同土层分布格局则不同。     

Substantial net N mineralization during the dormant season in temperate forest soils

In temperate forest soils, N net mineralization has been extensively investigated during the growing season, whereas N cycling during winter was barely addressed. Here, we quantified net ammonification and nitrification during the dormant season by in situ and laboratory incubations in soils of a temperate European beech and a Norway spruce forest. Further, we compared temperature dependency of N net mineralization in in situ field incubations with those from laboratory incubations at controlled temperatures. From November to April, in situ N net mineralization of the organic and upper mineral horizons amounted to 10.9 kg N (ha · 6 months)^–1 in the spruce soil and to 44.3 kg N (ha · 6 months)^–1 in the beech soil, representing 65% (beech) and 26% (spruce) of the annual above ground litterfall. N net mineralization was largest in the Oi/Oe horizon and lowest in the A and EA horizons. Net nitrification in the beech soil [1.5 kg N (ha · 6 months)^–1] was less than in the spruce soil [5.9 kg N (ha · 6 months)^–1]. In the range of soil temperatures observed in the field (0–8°C), the temperature dependency of N net mineralization was generally high for both soils and more pronounced in the laboratory incubations than in the in situ incubations. We suggest that homogenization of laboratory samples increased substrate availability and, thus, enhanced the temperature response of N net mineralization. In temperate forest soils, N net mineralization during the dormant season contributes substantially to the annual N cycling, especially in deciduous sites with large amounts of litterfall immediately before the dormant season. High Q₁₀ values of N net mineralization at low temperatures suggest a huge effect of future increasing winter temperature on the N cycle in temperate forests.     

灌溉施肥对壤质潮土硝态氮淋溶的影响

在衡水市邓庄乡壤质潮上上进行了以灌水为主处理、氮用量为副处理,各五水平的定位试验。结果表明,氮肥用量是硝态氮淋溶损失的决定因素,冬小麦施氮150kghm-2不发生淋溶,施氮225～300kghm-2则硝态氮的淋溶增强。小麦播前基施氮肥量过高会使冬季发生硝态氮的淋溶。小麦拔节期和灌浆期灌溉一般不会引起硝态氮的淋溶损失;尽管一次灌水1350m3hm-2硝态氮的淋失量不高,但土壤剖面中的硝态氮含量显著比低灌水量的低。为降低硝态氮的损失,应控制一次灌水量不超过1050m3hm-2。雨季降水导致大量硝态氮淋溶损失,防治雨季土壤硝态氮的淋溶损失至关重要。     

Conservation of Pteropus livingstonii based on roost site habitat characteristics on Anjouan and Moheli, Comoros islands

Livingstone's fruit bats, Pteropus livingstonii, (Pteropodidae: Chiroptera) are endemic to only two islands, Moheli and Anjouan of the Comoros Islands in the West Indian Ocean. With an estimated population of less than 2000 individuals, P. livingstonii is listed as Critically Endangered on the International Union for the Conservation of Nature's Red List. Yet the habitat characteristics of these giant fruit bats, or flying foxes, are poorly known. I conducted field research during 5 months in 1998 focused on finding new roost sites, measuring characteristics of both roost sites and roost trees at new as well as previously identified roost sites, and recording the same characteristics for a set of absence sites. I identified six new roost sites allowing me to measure the characteristics of 15 known roost sites and seven absence sites. The study spanned both dry and rainy seasons and I found a significant increase in the number of individuals at roost sites during the rainy season. Bat roost sites were associated with presence of water, southeast aspect, steep slopes, and presence of several native tree species. Roost habitat was characterized based on biotic, abiotic and human factors. This research on habitat characteristics is contributing to the development of a conservation action plan for the Livingstone's fruit bats. However, further research on dry season roost sites and distribution as well as feeding sites is necessary in order to better understand their seasonal habitat requirements and therefore ensure the conservation of P. livingstonii.     

Methods for conservation outside of formal reserve systems: The case of ants in the seasonally dry tropics of Veracruz, Mexico

Like most ecosystems of the world, tropical dry forests of the central coast of the Gulf of Mexico are inadequately preserved. Given that reserve expansion is unlikely, it is imperative that the conservation capacity of the matrix surrounding reserves is enhanced. Here, we examine the habitat value of isolated pasture trees and patches of secondary regrowth in terms of their terrestrial and arboreal ant assemblages in both a wet and dry season. These simplified wooded systems increase species densities within the agricultural matrix and provide habitat for some forest ant species. Estimated species richness of arboreal ants was particularly low on isolated trees, highlighting an important limitation. This was not the case for terrestrial ants, which were particularly species rich under isolated trees. We also found that the inter-site variations in species densities and similarity to the forest ant assemblage for terrestrial and arboreal strata were not correlated, suggesting that responses to restoration may not be as uniform as often thought. This has important implications for the use of indicator taxa in suggesting the response of other taxa. In terms of species composition, neither secondary regrowth nor isolated trees were appropriate replacements for forest fragments, even though the studied forest fragments were small (13-32 ha). The ant assemblages did not exhibit a seasonal change in composition. However, season influenced the contrast between habitats, with isolated trees being more distinct from pasture, and regrowth more closely resembling forests, during the wet season. Microclimatic variables indicate that the forests were least affected by the tropical dry season, and this may contribute to their characteristic fauna. We conclude that even small forest patches make a unique contribution to landscape conservation and that, where reserves are limited, conscientious management of the landscape matrix may provide some species with sufficient new habitat to survive outside of reserve systems. These conclusions are influenced by both season and strata studied.     

Effect of Raindrop Temperatures on Soil Runoff and Erosion in Dry and Wet Soils. A Laboratory Experiment

The effect of raindrop temperatures on runoff generation and erosion on clayey soil was investigated in sprinkling experiments with a laboratory rotating disk rain simulator. The experiments were applied to Rhodoxeralt (Terra Rossa) soil with two pre‐prepared moisture contents: hygroscopic and field capacity. For each moisture content, three rainfall temperatures were applied: 2, 20, and 35 °C. Erosion was generally lower in the pre‐wetted soil than in the dry soil (12.5 and 24.4 g m⁻² per 40 mm of rain, respectively). Whereas there was no significant effect of raindrop temperature on the dry soil, the soil that was pre‐moistened to field capacity was affected by rainwater temperature: runoff and erosion were high when the temperature difference between rainfall and soil surface was high, and sediment yields were 13·9, 5·2, and 18·3 g m⁻² per 40 mm of rain, for rain temperature of 2, 20, and 35 °C, respectively. It is reasonable to conclude that thermophoresis caused by thermal gradients within the soil solution reduces the stability of aggregates and then increases the soil losses. Copyright © 2016 John Wiley & Sons, Ltd.     

Ants (Hymenoptera: Formicidae) diversity in agricultural ecosystems at Mezquital Valley,Hidalgo, Mexico

We studied the changes in ant communities within agricultural ecosystems according with their seasonal variation and type of irrigation (well water and wastewater) in five plots. Plots were located in the Mezquital Valley, in the central Mexico. Collects were carried out in 2003, from February to March (dry season) and August (rainy season) using Pitfall traps. A total of 1638 organisms were collected (477 and 1161, dry and rainy season, respectively), corresponding to 16 genera, Pheidole (42.38%) and Monomorium (26.67%) were the most frequently collected. The capture frequency of ants was 0.58 throughout the whole study (0.45 and 0.71, dry and rainy season, respectively). An ANOVA two-ways analysis shows a significant season, plot and interaction effect on the ant capture frequency. A high diversity was observed during the rainy season (14 species). The plots with low disturbances show more species richness and abundance, indicating that the quality of the water is a determining factor for the community structure. The genera Tapinoma and Odontomachus could be indicators of low disturbance levels.