Biodegradation of litter in Eucalyptus pauciflora communities—II. Fungal succession in fungicide- and insecticide-treated leaves

Fungal succession on untreated and fungicide- and insecticide-treated leaves of Eucalyptus pauciflora was compared. Natural succession on untreated leaves fits the general scheme for succession on deciduous tree leaves. Initial colonizers are species of Coelomycetes and Moniliales. When the numbers of Coelomycetes decrease in the late stages of decomposition, the frequency of Penicillium species and species of Zygomycetes increases. The succession is affected only marginally by DDT and dieldrin treatment while benomyl severely restricts the occurrence of most fungal species. The effect of benomyl persists even after exposure for 48 weeks in the field.     

The spread and development of Rhododendron ponticum L. on dunes at Winterton,Norfolk, in comparison with invasion by Hippophaë rhamnoides L. at Saltfleetby,Lincolnshire

A survey was made in 1972, of the status of Rhododendron pronticum L. at Winterton, Norfolk, and aerial photographs were used to assess its spread in recent years. The ecological implications of the continuing presence of this invsive alien shrub on the dunes are discussed. Comparisons with the highly successfull dune shrub Hippophaë rhamnoides L. help put into perspective the present and likely future role of Rhododendron at Winterton. The implications of controls are discussed together with methods by which this may be achieved.     

Effects of a tropical cyclone on littoral and sub-littoral biotic communities and on a population of Dugongs (Dugong dugon (Müller))

The extensive damage to littoral and sub-littoral biotic communities caused by cyclone ‘Althea’, which crossed the tropical coast of Queensland on 24 December, 1971, are described. The effects of high wind speeds (mean 129·7 km/h), turbulent seas, storm surges, and heavy rainfall on mangrove, sea grass, algal, and coral reef communities are discussed. Mangroves withstood the immediate effects of the cyclone and protected coastal areas. However, long-term effects on mangroves are apparent. Severe wave action, shifting sand, and low salinities caused extensive damage to sea grass, algal, and coral reef communities. The effects of the cyclone on a Dugong population are described. The catches of Dugongs in shark nets set off Townsville increased from an average of 12·7 per year before the cyclone to 41 in 1972 (the year following the cyclone). This increase is attributed to increased movements in search of food, following extensive damage to sea grass beds. Associated with increased movements, there occurred a change in diet whereby large amounts of brown algae were eaten in addition to sea grasses. Sex and size (age) distributions of captured Dugongs are given and their possible significance discussed.     

Low dose γ-irradiation as a suitable solution for chestnut (Castanea sativa Miller) conservation: effects on sugars, fatty acids, and tocopherols

Along with dehydration, the development of insects and microorganisms is the major drawback in chestnut conservation. Irradiation has been regaining interest as an alternative technology to increase food product shelf life. In the present work, the effects of low dose gamma irradiation on the sugar, fatty acid, and tocopherol composition of chestnuts stored at 4 °C for different storage periods (0, 30, and 60 days) was evaluated. The irradiations were performed in a 60Co experimental equipment, for 1 h (0.27±0.04 kGy) and 2 h (0.54±0.04 kGy). Changes in sugars and tocopherols were determined by high performance liquid chromatography coupled to refraction index and fluorescence detections, respectively, while changes in fatty acids were analyzed by gas-chromatography coupled to flame ionization detection. Regarding sugar composition, storage time proved to have a higher effect than irradiation treatment. Fructose and glucose increased after storage, with the corresponding decrease of sucrose. Otherwise, the tocopherol content was lower in nonirradiated samples, without a significant influence of storage. Saturated, monounsaturated, and polyunsaturated fatty acids levels were not affected, either by storage or irradiation. Nevertheless, some individual fatty acid concentrations were influenced by one of two factors, such as the increase of palmitic acid in irradiated samples or the decrease of oleic acid after 60 days of storage. Overall, the assayed irradiation doses seem to be a promising alternative treatment to increase chestnut shelf life, without affecting the profile and composition in important nutrients.     

Does moder development along a pure beech (Fagus sylvatica L.) chronosequence result from changes in litter production or in decomposition rates?

The development of temperate deciduous and conifers forests stands usually results in accumulation of forest floor organic matter and a shift from mull to moder humus forms. It has been suggested that an increase in nutrient uptake by trees during their rapid growth phase leads to topsoil acidification, decrease in earthworm density and thereby a decrease in litter turnover. The focus of this paper was to examine if the mull-moder shift with forest ageing results from higher leaf litter production and/or lower litter decay rates. The objectives of this research were to determine (1) changes in macro-morphological properties of humus forms, leaf litter production, litter decay rates, soil nutrients content and pH along a 130-year pure beech (Fagus sylvatica L.) chronosequence in Normandy (Northwest France), (2) if humus form varied from mull to moder with increasing stand age, and (3) if a shift from mull to moder resulted from increased litter production, decreased litter decay rates, or both. Annual litter production did not change significantly along the chronosequence (mean 2.41 t ha⁻¹). In contrast, litter decay rates decreased significantly during the rapid growth phase of trees. In consequence, the litter turnover time (1/k) was lower in the youngest stands (20 months) compared to the oldest ones (31 months). Even in the absence of a significant pattern of variation, litter production was positively correlated with the thickness of the OF (Oi) horizon. In contrast, litter decay was strongly negatively correlated with maximum thickness of the OH (Oa) horizon, suggesting that the appearance of the humification layer was mainly due to a decrease in litter decay rate. We did not find significant changes in the main properties of the organo-mineral horizon, suggesting that soil nutrient availability may not directly affect litter dynamics. We concluded that moder development along the chronosequence resulted in decreasing litter decay rates during the aggradation phase while litter production was stable. Further studies are required to identify the ecological factors responsible for moder development along forest ageing.     

Effects of wood char and activated carbon on the hydrolysis of cellobiose by β-glucosidase from Aspergillus niger

Biochar amendments to soils have been suggested as a strategy to sequester carbon and therefore mitigate global climate change. The enrichment of soils with charred materials also increases their fertility. This fertilising effect of biochar may be caused by various mechanisms; an acceleration of nutrient cycling has been suggested as one such mechanism. The rate-limiting step in nutrient cycling is thought to be the extracellular enzymatic attack on biological macromolecules. In this study, therefore, the effects of chestnut wood char (specific surface area 2.0 m² g⁻¹) and of activated carbon (specific surface area approximately 900 m² g⁻¹) on an extracellular enzymatic reaction involved in the degradation of cellulose (i.e., hydrolysis of cellobiose by β-glucosidase from Aspergillus niger) were investigated. Cellobiose was not adsorbed by chestnut wood char, whereas activated carbon absorbed more than 97% of it. Both charred materials adsorbed more than 99% of β-glucosidase. For chestnut wood char, adsorption of the enzyme caused a decrease of approximately 30% in the reaction rate, whereas for activated carbon, the nearly complete absorption of both substrate and enzyme entirely inhibited the reaction. These results show that β-glucosidase from A. niger retains most of its activity when adsorbed to chestnut wood char and that the reaction it catalyses in nature is only slightly affected by this charred material. On the other hand, a material characterised by a high specific surface area and high porosity, such as activated carbon, can make even a highly soluble substrate unavailable for soil enzymes and therefore completely inhibit the reaction. Thus, charred materials may affect nutrient cycling mainly by regulating the availability of substrates: the degradation of highly soluble substrates may be accelerated by materials with low specific surface area, which maintain an active and protected enzyme pool, whereas materials with high specific surface and high porosity may slow down the degradation by making substrates unavailable.     

Do oribatid mites (Acari: Oribatida) show a higher preference for ubiquitous vs. specialized saprotrophic fungi from pine litter?

Previous studies of oribatid mite feeding preferences for different saprotrophic fungi were limited to ubiquitous fungal species, whereas saprophytes specialized to decompose particular substrates have been neglected. We examined the preference of seven oribatid mite species (Adoristes ovatus, Eniochthonius minutissimus, Eueremaeus silvestris, Nothrus silvestris, Oppiella subpectinata, Porobelba spinosa and Spatiodamaeus verticillipes) for nine autochthonous saprotrophic fungi from Scots pine litter (Pinus sylvestris). Among the fungal species offered were specific coniferous litter colonizers (Allantophomopsis lycopodina, Ceuthospora pinastri, Hormonema dematioides, Scleroconidioma sphagnicola, Verticicladium trifidum, Marasmius androsaceus and Sympodiella acicola) and two ubiquitous species (Cladosporium herbarum and Oidiodendron griseum). The fungi were inoculated on fragments of pine needles and offered simultaneously and separately to the mites. Our main hypothesis, that oribatid mites (usually occurring in more than one type of ecosystems) would prefer the ubiquitous fungal species rather than those specific to pine litter, was supported only partly. The ubiquitous C. herbarum was highly preferred by all studied mites, but most of them preferred one or more of the specialized fungi with similar intensity. The basidiomycete M. androsaceus along with sterile needles were consistently avoided by all mites in all experiments. Our results do not support the hypothesis, that the “true” fungivorous oribatid mites in traditional sense are more selective fungal feeders than are the “unspecialized” panphytophagous ones. We observed no gradation in preference of fungi for oribatid mites as a group, but rather a discontinuous and dynamic mosaic with particular mites preferring particular fungal species. This heterogeneous mosaic shapes the feeding niches occupied by particular oribatid mite species and probably reduces competition for food source among numerous species coexisting in a given habitat and time.     

Rhizobia in tropical legumes—VII. Effectiveness of different isolates on Psophocarpus tetragonolobus (L.) DC

Rhizobia isolated from fourteen different genera of legumes were tested for their N-fixing effectiveness with Psophocarpus tetragonolobus in standard Leonard jar trials. Isolates from all plants except Pithecellobium jiringa were able to form nodules with P. tetragonolobus although a wide range of effectiveness amongst the different rhizobia was demonstrated. Thus P. tetragonolobus may be considered promiscuous with respect to its rhizobial requirements. Based on this experiment, a group of rhizobia comprising three elite strains (RRIM 56 from P. tetragonolobus, UMKL 36 from Lablab purpureus and CB 756 from Macrotyloma africanum, a moderately effective strain (NGR 258 from P. tetragonolobus), and two strains of low effectivity (RRIM 968 from Centrosema pubescens and UMKL 12 from Phaselus angularis) were selected for further study. When these were used to inoculate P. tetragonolubus growing in soil taken from virgin jungle (less than 1.54 rhizobia g^?1 soil); RRIM 56 and UMKL 36 again performed well, but NGR 258 outperformed CB 756.     

Catalytic Effect of a Semiconductor on the Removal of Hexavalent Chromium from Aqueous Solution by γ-Ray Irradiation

Hexavalent chromium is a type of toxic chemical, it may cause allergies, hereditary genetic defects and cancer in humans by inhalation, and it is also a persistent danger to the environment. However, chromium metal, trivalent chromium and tetravalent chromium have low toxicities. In this study, semiconductor materials (quartz fibre and TiO₂) were added to a hexavalent chromium solution and the removal efficiency of hexavalent chromium as a function of the γ-ray irradiation dose, as well as the catalytic mechanism, was investigated. It was observed that the reduction of hexavalent chromium by γ-ray irradiation was largely promoted in the presence of semiconductor materials; the semiconductor materials act as catalysts under the gamma-ray irradiation. The hexavalent chromium in the solution can be converted to an insoluble precipitate by gamma-ray irradiation. These results are highly beneficial to apply semiconductor materials as catalysts for the removal of contaminants by radiation.     

Variation of soil microbial biomass C and hydrolytic enzyme activities in a rangeland ecosystem: are slope aspect and position effective?

This study was conducted to investigate the effects of slope aspect and position on microbial biomass C (MBC) and some hydrolytic enzyme activities involved in soil N, P, and S cycles in a rangeland ecosystem of west central Iran. Soil samples were collected from three slope positions (summit, backslope, and footslope) of contiguous north- and south-facing slopes. Results indicated higher silt and clay content, soil organic C (SOC), total N (TN), and C/N ratio on the north-facing slope. Furthermore, MBC, alkaline phosphomonoesterase (ALP), acid phosphomonoesterase (ACP), arylsulfatase (ARS), urease (URS), L-asparaginase (LAS), and L-glutaminase (LGL) activities were greater by 46.1, 65.9, 58.6, 59.6, 52.6, 62.8, and 65.7%, respectively, on the north-facing slope compared to the south-facing one. Higher ratios of enzyme activities to MBC were observed on the north-facing slope. In contrast, per cent of inorganic N and microbial quotient were greater on the south-facing slope. The activity of ALP, ACP, ARS along with SOC, TN, and MBC values decreased from summit to footslope. Overall, our findings indicate that north-facing slope and summit position support greater microbial biomass and hydrolytic diversity.     

Effects of epigeic earthworm (Eisenia fetida) and arbuscular mycorrhizal fungus (Glomus intraradices) on enzyme activities of a sterilized soil–sand mixture and nutrient uptake by maize

A pot experiment was conducted to investigate the effect of epigeic earthworm (Eisenia fetida) and arbuscular mycorrhizal (AM) fungi (Glomus intraradices) on soil enzyme activities and nutrient uptake by maize, which was grown on a mixture of sterilized soil and sand. Maize plants were grown in pots inoculated or not inoculated with AMF, treated or not treated with earthworms. Wheat straw was added as a feed source for earthworms. Mycorrhizal colonization of maize was markedly increased in AM fungi inoculated pots and further increased by addition of epigeic earthworms. AM fungi and epigeic earthworms increased maize shoot and root biomass, respectively. Soil acid phosphatase activity was increased by both earthworms and mycorrhiza, while urease and cellulase activities were only affected by earthworms. Inoculation with AM fungi significantly (p?<?0.001) increased the activity of soil acid phosphatase but decreased soil available phosphorus (P) and potassium (K) concentrations at harvest. Addition of earthworms alone significantly (p?<?0.05) increased soil ammonium-N content, but decreased soil available P and K contents. AM fungi increased maize shoot weight and root P content, while earthworms improved N, P, and K contents in shoots. AM fungi and earthworm interactively increased maize shoot and root biomass through their regulation of soil enzyme activities and on the content of available soil N, P, and K.     

Studies on microörganisms and their activities in soil Part. 2. Virgin and cultivated soil of the same origin

The nature of soil is modified differently depending upon the artificial condition such as its utilization or management. It is therefore expected that the microbiological characteristic of soil is changed also. Greaves¹⁾ and Williams²⁾ reported that the reclamation of virgin soil brought about a change of bacterial count. Suzuki et al³⁾ observed that the kind of fungi differed between a virgin and a cultivated soil and that the vegetative mycelium was numerous in the former than in the latter. On the other hand, according to W aksman and Starkey⁴⁾, the bacterial count differed depending upon the fertility of soil. Singh⁵⁾ reported also that the number of fungi and actinomycetes was higher in a fertile than in an infertile soil. Lochhead⁶⁾, and Lochhead and Chasen studied the bacterial flora of a fertile (long-continued application of manure) and an infertile (no fertilizer for many years) soil and found that a certain difference could be observed when morphological, physiological and nutritional classification are tried.     

Rhizobia in tropical legumes—VIII. Serological characteristics of Psophocarpus tetragonolobus (L.) DC. isolates

Antisera were prepared against six inoculant strains of rhizobia for Psophocarpus tetragonolobus, and used to react with 62 different strains in both agglutination and immunodiffusion systems. A wide array of reactions occurred, indicating the extent of heterogeneity amongst strains capable of nodulating the same host. In agglutination reactions, the heat-stable somatic antigens could be arranged in 25 serogroups. In gel diffusion, antigens which produced strong precipitin bands usually showed agglutination relationships, but the corollary was not true. The immunodiffusion technique easily distinguished homologous and cross-reacting reactions and could be reliably used in field experiments with P. tetragonolobus.     

Penicillium bilaii effects on maize growth and P uptake from soil and localized sewage sludge in a rhizobox experiment

With P being a non-renewable resource, the use of microbial inoculants and waste products for more efficient and sustainable P use in plant production has been proposed. We investigated the ability of Penicillium bilaii to mobilize P in a low-fertility soil with or without amendment of sewage sludge as additional P source. Maize was grown for 27 days in rhizoboxes enabling studies of root growth in addition to plant and soil parameters. P. bilaii was inoculated either at the seed or the sewage sludge patch. At early growth stages, P. bilaii inoculation of seeds increased maize shoot length. However, at the end of experiment, the effect had ceased. Root growth was increased by seed P. bilaii inoculation alone and in combination with sewage sludge, whereas patch inoculation was less effective. Colonization studies performed at harvest showed that P. bilaii could not be detected in the maize rhizosphere but stayed at the place of inoculation. In sewage sludge patches, the growth of Penicillium strains other than P. bilaii was stimulated; hence, using sewage sludge for combined P resource and carrier of microbial inoculants is discussed. Unexpectedly, the greater root development of seed-inoculated plants did not result in increased plant P uptake and neither did inoculation at the sewage sludge patch. This study raises the question if the soil P status can be too low for a beneficial effect of additional early root growth and thus a beneficial effect of seed inoculation of P. bilaii.     

Molecular diversity of restriction enzyme sites, Indels and upstream open reading frames (uORFs) of 5′ untransalted regions (UTRs) of Waxy genes in Triticum L. and Aegilops L. species

5′ Untransalted regions (UTR) sequences of Waxy genes were amplified from all 81 Triticum L. and Aegilops L. species by PCR with specific primers. It was found that the sequence length at 7D loci was longer than that 7B and 7A. These sequences contained 170 singleton variable sites and 484 polymorphic sites and that the average length of Indels was 8.5?bp. There were abundant regions of restriction enzyme sites and two regions of simple sequence repeat, “GAA” and “CTGA”, in all sequences. A total of 65 uORFs were detected and classed into 37 types, with the variation in uORFs mainly due to single nucleotide polymorphisms (SNPs), and also to the presence of Indels. All sequences in tetraploids and hexaploids could be grouped into Types A, B, I, II, GI and GII based on sequence variation. Restriction enzyme sites, Indel polymorphisms and the classes of uORFs present together indicated that Type I was more similar to Ae. tauschii whereas Type II was more similar to Type B, and both more similar to Ae. longissima; Type A was more similar to Ae. speltoides. Population analysis was performed and Neighbour-joining trees derived from different species, types and accessions further confirmed that the ancestors of T. urartu, Ae. speltoides, Ae. longissima and Ae. tauschii were involved to the evolution of common wheat, and also implied that Ae. longissima might have participated later than Ae. speltoides. 5′ UTRs of Waxy genes in tetraploid and hexaploid species conserved characters from their respective progenitors when compared with diploid. For the first time, we are able to conclude there is abundant variation in SNPs, Indels and uORFs between 5′ UTRs of Waxy genes from different species related to common wheat, and suggest that further research could help to understand Waxy gene function more deeply and hence improve wheat breeding. Our results also show that three hexaploid species in China have unique diversity in the 5′ UTR of their Waxy gene.     

Is the western population of the European mink, (Mustela lutreola), a distinct Management Unit for conservation?

The European mink (Mustela lutreola) is one of the most threatened carnivores in Europe, with fragmented populations in Belarus, Russia and Romania, as well in south-western France and northern Spain. Many populations have become extinct recently, or are declining. We investigated mitochondrial DNA variation, using the complete D-loop region, and concentrating on the west European population. The aim was two-fold: to use the genetic information to advise on the conservation of European mink, and to begin to understand their history through the Pleistocene. Captive breeding and re-introduction programmes are underway, so it is particularly vital to know whether the West European population should be treated separately. We find that European mink probably colonised from a single refugium after the last glaciation. West European populations may be fixed for a single haplotype, also suggesting a common origin. Despite this evidence for gene flow, following the precautionary principle we suggest that mink from the three geographically separate populations (Romania, Eastern and Western Europe) should be managed separately, for the moment.     

Land use effects on microbial biomass C, β-glucosidase and β-glucosaminidase activities,and availability,storage, and age of organic C in soil

Microbial biomass, β-glucosidase and β-glucosaminidase activities, and availability, storage, and age of soil organic C were investigated after 26 years of conversion from sugarcane (Saccharum officinarum) to forest (Eucaliptus robusta or Leucaena leucocephala), pasture (mixture of tropical grasses), and to vegetable cropping (agriculture) in a vertisol in Puerto Rico. Soil organic C (SOC) at 0–100 cm was similar under Leucaena (22.8 kg C/m²), Eucalyptus (18.6 kg C/m²), and pasture (17.2 kg C/m²), which were higher than under agriculture (13.0 kg C/m²). Soil organic N (SON) at 0–100 cm was similar under the land uses evaluated which ranged from 1.70 (under agriculture) to 2.28 kg N/m² (under Leucaena forest). Microbial biomass C (MBC) and N (MBN) of the 0–15-cm soil layer could be ranked as: pasture > Leucaena = Eucalyptus > agriculture. The percentages of SOC and SON present as MBC and MBN, respectively, were nearly 1% in pasture and less than 0.50% in forest under Leucaena or Eucalyptus and agricultural soil. The activity of β-glucosidase of the 0–15-cm soil layer could be ranked as: Leucaena = Eucalyptus > pasture > agriculture; while β-glucosaminidase activity was ranked as: Eucalyptus > Leucaena = pasture > agriculture. The soil δ ¹³C changed from 1996 to 2006 in forest under Eucalyptus (18.7‰ to 21.2‰), but not under Leucaena (20.7‰ to 20.8‰). The soil under Leucaena preserved a greater proportion of old C compared to the forest under Eucalyptus; the former had an increased soil mineralizable C from the current vegetation inputs. The soil under agriculture had the lowest enzyme activities associated with C cycling, lowest percentage of SOC as MBC, highest percentage of SOC present as mineralizable C, and highest percentage of MBC present as mineralizable C compared to the other land uses.     

Effects of K-Mg ratio on growth and cation nutrition of Vitis vinifera L. cv. “Dattier de Beiruth” grafted on SO4 rootstock

The area of planting of Vitis vinifera L. cv. “Dattier de Beiruth” (DB) grafted on the SO4 (Selection OPPENHEIM 4) rootstock is significant and constantly growing in Northern Algeria. A hydroponic culture was carried out with DB to investigate the effects of potassium-magnesium (K-Mg) ratio on plant growth and mineral nutrition. Four nutrient solutions were tested on which the K-Mg ratio is variable (nutritive solution (NS)1 = 0.3 K: 3.8 Mg, NS2 = 2.1 K: 2 Mg, NS3 = 2.6 K: 1.5 Mg and NS4 = 3.8 K: 0.3 Mg). The results showed that DB was characterized by a high capacity for K uptake. No significant differences among the treatments were detected in the leaf concentrations of calcium (Ca), however Mg uptake was inhibited by increase of K: Mg in the nutrient solution. Results showed that DB is sensitive to the variation of the cation composition in the nutrient solution. Antagonism between K-Mg was apparent.     

Rhizobia in tropical legumes—IX. pot and field trials with inoculants for Psophocarpus tetragonolobus (L.) DC.

Antigenically identifiable inoculants for Psophocarpus tetragonolobus were evaluated in three non-sterile soils contained in pots (sandy-clay, Renggam series; a loamy-sand, Sungei Buloh series; silty-clay, Munchong series). Most-probable-numbers of indigenous rhizobia ranged from 4 (Renggam series) to 13 (Munchong series) g^?1. Only two (RRIM 56 and 968) of the eight rhizobia tested formed > 50% of the nodules in all soils. Recovery of two strains (RRIM 968 and UMKL 12) was significantly poorer from the Munchong series soil which had the most indigenous rhizobia and the highest silt plus clay content. In a field trial using a Sungei Buloh series soil containing 700 rhizobia g^?1 capable of nodulating P. tetragonolobus, none of the applied strains formed > 18% of the nodules; two formed no nodules. There were no significant increases in plant yield in response to inoculation in the field trial and in two soils in the pot trials. In Sungei Buloh series soil, RRIM 56 formed 90% of the nodules when the indigenous rhizobia were 5 cells g^?, and 14% when the population was 700 g^?1. This raises the question of the need to inoculate seed sown into soils with high indigenous rhizobial populations, but there was some indication of increasing representation of inoculant strains in nodules with time.     

Lestes dryas kirby—a declining species of dragonfly (odonata) in need of conservation: Notes on its status and habitat in England and Ireland

A study of Lestes dryas was made in 1978. None was found in ten localities in south east England, which had held populations in the period 1940–1947. Major changes had occurred in eight of the localities, and these could readily account for the disappearance of the insect from them. A search for L. dryas was made in apparently suitable habitat in the Cambridgeshire Fens but none was found. L. dryas was found on three out of eighty waterbodies visited in the west and south of Ireland. Neutral or slightly acid waters with extensive emergent vegetation, notably Equisetum fluviatile, Scirpus lacustris and Typha sp., and supporting the dragonflies Sympertrum sanguineum and/or Coenagrion pulchellum, appear to indicate a suitable habitat for the species. The decline of L. dryas appears to have been caused by a combination of factors: loss of habitat, periods of drought and small population numbers.