Decomposition of kitchen waste amended with cow manure using an epigeic species (Eisenia fetida) and an anecic species (Lampito mauritii)

An epigeic (surface dweller) earthworm species Eisenia fetida and an anecic (deep burrower) earthworm species Lampito mauritii have been tested for decomposition of kitchen waste plus cow dung. Chemical analyses of worm-worked substrates by both species showed g/kg increases in nitrogen, phosphorus and potassium and decreases in C/N and C/P ratios after 150 days of vermicomposting. However, organic carbon matter showed reduction in their amounts for 3-4 months and afterwards slightly increased up to 150 days. E. fetida produced 0.27%, 156%, 41% and 38% increases in organic carbon, nitrogen, phosphorus, and potassium as well as 61% and 29% decreases in C/N and C/P ratios as compared to control after 150 days of earthworm inoculation. In contrast, L. mauritii produced 14%, 102%, 33% and 42% increases in organic carbon, nitrogen, phosphorus and potassium as well as 43% and 14% decreases in C/N and C/P ratios as compared to control after 150 days of earthworm activity. There was moderate mineralization and faster decomposition by E. fetida in comparison to moderate mineralization and moderate decomposition by L. mauritii. The average numbers of cocoons and adults produced were greater by E. fetida than by L. mauritii after 150 days. These results indicate E. fetida may be a better adapted species for decomposition of kitchen waste plus cow dung under tropical conditions.     

Explaining density-dependent regulation in earthworm populations using life-history analysis

At present there is little knowledge about how density regulates population growth rate and to what extent this is determined by life-history patterns. We compared density dependent population consequences in the Nicholsonian sense based on experimental observations and life-history modeling for the earthworms Lumbricus terrestris and Eisenia fetida . Both species differ in their life-histories, L. terrestris being a relatively long-lived species with slow reproduction and occurring at low densities compared to E. fetida which has a more opportunistic strategy with a high reproductive output. E. fetida is able to colonise new habitats rapidly and may occur at relatively high population densities. Density dependency of population growth rate was estimated by incorporating density dependent effects on reproduction and growth using a modified Euler equation. The results point out that E. fetida was not as strongly impacted by density as compared to L. terrestris . Population growth rate in E. fetida was hardly affected at low and moderate density, being reduced only at high level, this compares to L. terrestris where even relatively small density effects resulted in a strong negative effect on population growth rate. Our findings indicate that density-dependent regulation in earthworms can be quantified using life-history analysis. The outcomes are in agreement with empirical field observations for populations (i.e. L. terrestris occurs ar low density, E. fetida at high density). Consideration of the potential importance of Nicholsonian density dependence for field populations of these two species in light of their known biology however produces counterintuitive conclusions. In E. fetida , although density tolerant, rapid population growth may mean this species may be subject to density dependeny regulation. In L. terrestris , although density sensitive, complex behavioural ecology (surface activity, territoriality) may limit of feedback influence on population size.     

Seasonal population dynamics of Eisenia fetida (Savigny, 1826) (Oligochaeta, Lumbricidae) in the field

In order to assess the response of epigeic earthworms to seasonal changes we monitored the population dynamics of Eisenia fetida (Oligochaeta, Lumbricidae) in a manure heap in the field during a year. Earthworms were hand-sorted from five 0.25 x 0.25 x 0.20 m blocks around the heap in November (autumn) 1999 and in January (winter), April (spring) and August (summer) 2000 to determine earthworm population dynamics. Earthworms of each block were classified into different age classes: mature, preclitellate, juvenile, hatchling and cocoon, and afterwards counted and weighed. Seasonality had a strong effect on the density, biomass and reproductive activity of the population. The population of E. fetida was characterized by a high density of individuals and the predominance of mature individuals throughout the year. Maximum density, mating activity and size of cocoons were achieved in spring, but there were not changes in the number of cocoons per mature earthworm throughout the year. Unexpectedly, the smallest cocoons were produced in winter by the largest individuals. These results suggest that E. fetida is able to allocate resources to growth and/or reproduction in response to environmental fluctuations.     

Municipal solid waste management through vermicomposting employing exotic and local species of earthworms

A comparative study was conducted between exotic and local (epigeic--Eisenia fetida and anaecic--Lempito mauritii, respectively) species of earthworms for the evaluation of their efficacy in vermicomposting of municipal solid waste (MSW). Vermicomposting of MSW for 42 days resulted in significant difference between the two species in their performance measured as loss in total organic carbon, carbon-nitrogen ratio (C:N) and increase in total Kjeldahl nitrogen, electrical conductivity and total potassium and weight loss of MSW. The change in pH and increase in number of earthworms and cocoons and weight of earthworms were non-significant.     

Some effects of soil-moisture availability on above-ground production and reproductive allocation in Larrea tridentata (DC) Cov

Summary Data from the US/IBP Desert Biome validation studies indicate that above-ground production and biomass allocated to reproduction in Larrea tridentata vary from one year to another depending upon the timing and extent of soil-moisture availability. In an attempt to verify these observations and determine to what extent water availability can affect total aboveground production and reproductive allocation in this widely distributed warm desert shrub, a series of soil-moisture augmentation experiments were conducted. High levels of soil moisture had a greater effect on reproductive allocation than on total above-ground production. Enhanced soil moisture during the period of active growth increased total above-ground production and reduced the percentage of biomass allocated to reproduction. Enhanced soil moisture during the normal periods of little or no growth did not increase total above-ground production.     

Predominant role of water in regulating soil and microbial respiration and their responses to climate change in a semiarid grassland

Climate change can profoundly impact carbon (C) cycling of terrestrial ecosystems. A field experiment was conducted to examine responses of total soil and microbial respiration, and microbial biomass to experimental warming and increased precipitation in a semiarid temperate steppe in northern China since April 2005. We measured soil respiration twice a month over the growing seasons, soil microbial biomass C (MBC) and N (MBN), microbial respiration (MR) once a year in the middle growing season from 2005 to 2007. The results showed that interannual variations in soil respiration, MR, and microbial biomass were positively related to interannual fluctuations in precipitation. Laboratory incubation with a soil moisture gradient revealed a constraint of the temperature responses of MR by low soil moisture contents. Across the 3 years, experimental warming decreased soil moisture, and consequently caused significant reductions in total and microbial respiration, and microbial biomass, suggesting stronger negatively indirect effects through warming‐induced water stress than the positively direct effects of elevated temperature. Increased evapotranspiration under experimental warming could have reduced soil water availability below a stress threshold, thus leading to suppression of plant growth, root and microbial activities. Increased precipitation significantly stimulated total soil and microbial respiration and all other microbial parameters and the positive precipitation effects increased over time. Our results suggest that soil water availability is more important than temperature in regulating soil and microbial respiratory processes, microbial biomass and their responses to climate change in the semiarid temperate steppe. Experimental warming caused greater reductions in soil respiration than in gross ecosystem productivity (GEP). In contrast, increased precipitation stimulated GEP more than soil respiration. Our observations suggest that climate warming may cause net C losses, whereas increased precipitation may lead to net C gains in the semiarid temperate steppe. Our findings highlight that unless there is concurrent increase in precipitation, the temperate steppe in the arid and semiarid regions of northern China may act as a net C source under climate warming.     

Potential of two epigeic and two anecic earthworm species in vermicomposting of water hyacinth

The potential of two epigeic species (Eudrilus eugeniae Kinberg, and Perionyx excavatus Perrier) and two anecic species (Lampito mauritii Kinberg and Drawida willsi Michaelson) of earthworms was assessed in terms of efficiency and sustainability of vermicomposting water hyacinth (Eichhornia crassipes, Mart. Solm.). In different vermireactors, each run in duplicate with one of the four species of earthworms, and 75 g of 6:1 water hyacinth:cowdung as feed, vermicasts were produced with steadily increasing output in all the reactors. E. eugeniae was by far the most efficient producer of vermicasts, followed by the other epigeic P. excavatus. The two anecics came next, with D. willsi being the least effective which could generate only about half the quantity of vermicasts achieved in a corresponding time by E. eugeniae. In all the reactors, the earthworms grew well, increasing their weights by more than 250%. The maximum net gain of weight (average 30.7 g) was by E. eugeniae, followed by P. excavatus, L. mauritii and D. willsi. This trend, which followed the efficiency of vermicast production, was also shown in terms of reproductive ability as measured by the number of offspring produced by the four species.     

Reproductive allocation strategies in desert and Mediterranean populations of annual plants grown with and without water stress

Reproductive effort (relative allocation of biomass to diaspore production) was compared in matched pairs of Mediterranean and desert populations of three unrelated annual species, Erucaria hispanica (L.) Druce, Bromus fasciculatus C. Presl. and Brachypodium distachyon (L.) Beauv., grown under high and low levels of water availability in a common-environment experiment. Desert populations in all three species showed higher reproductive effort than corresponding Mediterranean populations, as expressed by both a reproductive index (RI= reproductive biomass/vegetative biomass), and a reproductive efficiency index (REI=number of diaspores/total plant biomass). Moreover, in E. hispanica and Brachypodium distachyon, inter-populational differences in reproductive effort were greater under water stress, the main limiting factor for plant growth in the desert. These results indicate that variability in reproductive effort in response to drought is a critical and dynamic component of life history strategies in annual species in heterogeneous, unpredictable xeric environments. When subjected to water stress the Mediterranean populations of E. hispanica and B. distachyon showed greater plasticity (e.g. had a greater reduction) in reproductive effort than the desert populations, while in Bromus fasciculatus both populations showed similar amounts of plasticity.     

Vermiconversion of industrial sludge for recycling the nutrients

The aim of the present study was to investigate the transformation of sugar mill sludge (PM) amended with biogas plant slurry (BPS) into vermicompost employing an epigeic earthworm Eisenia fetida. To achieve the objectives experiments were conducted for 13 weeks under controlled environmental conditions. In all the waste mixtures, a decrease in pH, TOC, TK and C:N ratio, but increase in TKN and TP was recorded. Maximum worm biomass and growth rate was attained in 20% PM containing waste mixture. It was inferred from the study that addition of 30-50% of PM with BPS had no adverse effect on the fertilizer value of the vermicompost as well as growth of E. fetida. The results indicated that vermicomposting can be an alternate technology for the management and nutrient recovery from press mud if mixed with bulking agent in appropriate quantities.     

Mechanism of salt tolerance in wild rice (Oryza coarctata Roxb)

Summary Oryza coarctata, a highly salt-resistant wild rice species, is commonly found on the banks of coastal rivers in India. This species can also withstand saline water (20 to 40 dSm⁻¹ E.C) submergence for quite a long period. It was revealed thatO. coarctata has some special unicellular salt hairs (trichomes) on the adaxial surface of the leaves, by which they efficiently maintain a low concentration of toxic salts in the plant tissue. Sodium and chloride were the dominant ions in the excreted material but they also excrete potassium, magnesium and calcium. With the increase in soil salinity sodium, magnesium and chloride excretion increased.O. coarctata maintained the optimum mineral concentration in its tissues. Maximum accumulation of potassium was observed in the leaves. With the increase in salt stress total biomass production and osmotic potential increased over control but there was no change in the moisture percentage of leaves.     

Warming effects on shoot developmental growth and biomass production in sympatric evergreen alpine dwarf shrubs Empetrum nigrum and Loiseleuria procumbens

Effects of experimental warming on shoot developmental growth and biomass production were preliminarily investigated in two evergreen dwarf shrubs Empetrum nigrum and Loiseleuria procumbens, using the International Tundra Experiments open-top chamber (OTC) method, in the Tateyama Range, central Japan. An OTC was installed over shrub (E. nigrum and L. procumbens) -dominated vegetation and over shrub-forb (such as Anemone narcissiflora var. nipponica and Solidago virga-aurea ssp. leiocarpa) mixed vegetation, and stem samples of the evergreen shrubs were obtained at 26 months after installing the OTC. The OTC increased the daily mean temperature by 0.1°C to 1.8°C, on average, during the growing season. Shoot developmental growth and biomass production were considerably different between species of different vegetation types. The boreal species E. nigrum generally showed better growth inside the OTC than the arctic and subarctic species L. procumbens. Both species showed significantly larger shoot elongation and biomass production inside the OTC over shrub-dominated vegetation, whereas smaller or reduced growth was detected inside the OTC over shrub-forb mixed vegetation. The variations of growth responses to warming between species of different vegetation types are discussed, especially in relation to interspecific competition under a simulated environmental change.     

羊尿对典型草原不同生活型草地植物生长特性的影响

连续2a研究了施尿量(4,2,1L/m2和0 L/m2)和施尿期(营养期和生殖期)对典型草原多年生密丛型禾本科植物长芒草(Stipa bungeana)、多年生轴根型菊科植物茵陈蒿(Artemisia capillaries)和多年生半灌木豆科植物胡枝子(Lespedeza davurica)生长特性的影响.结果表明,不同植物对畜尿沉积的响应不同,并受施尿量和施尿时期的作用.畜尿对草地植物具短期(4周内)灼烧作用,灼烧主要发生于尿斑中心;畜尿对长芒草生长具长期正效应(4周后),对茵陈蒿和胡枝子生长具持续负效应,此效应持续至少2a且随施尿量降低而降低.一般尿斑中心(4 L/m2)所有植物伤害,尿斑中心至边缘圈植物局部器官(嫩枝叶)伤害(2～4 L/m2),尿斑外渗区域(1～2 L/m2)所有植物无显著伤害.高施尿量(2～4 L/m2)下,长芒草具较高的年均分蘖数和地上生物量,而胡枝子和茵陈蒿与之相反.尿斑处3种植物具较高的分蘖(枝)死亡率和死物质率.茵陈蒿对各时期施尿均反应敏感,胡枝子和长芒草对生殖期施尿更敏感.尿斑处禾草枯黄期延迟,返青期提前.     

Competition between two invasive Hydrocharitaceae (Hydrilla verticillata (L.f.) (Royle) and Egeria densa (Planch)) as influenced by sediment fertility and season

Competition between two invasive plants of similar growth form, Hydrilla verticillata (L.f.) (Royle) and Egeria densa (Planch), was studied in response to season and sediment fertility. These two invasive species were grown in outdoor concrete tanks in monocultures and mixtures. Five fertilization rates were tested for monocultures and two for mixtures where six combinations of planting densities were used in two seasons (spring and fall). Monitoring of plant biomass was made at the end of each of these 2-month-experiments. In contrast to E. densa, clear seasonal patterns in biomass production and in reproductive allocations of H. verticillata were evident. Competitive pressure for both species was lower during the fall experiment. Biomass production increased with fertilization for H. verticillata in monocultures and changes either in allocative ratios or in tuber production patterns were shown in response to nutrient availability. However, E. densa growth was not affected by fertilization. In most cases, H. verticillata was a better competitor than E. densa except when sediment was pure sand. Competition occurred mainly for nutrient uptake rather than for light harvesting. These results suggest that despite the similar ecology, H. verticillata may outcompete E. densa in many situations, probably due to its higher plasticity.     

Sexual dimorphism and cost of reproduction in the dioecious shrub Lindera benzoin (Lauraceae)>

We examined sexual dimorphism in reproductive allocation and its effects on growth and subsequent reproduction in a natural population of the dioecious woody shrub Lindera benzoin (L.) Blume. In addition to comparing natural patterns of growth and reproduction in a marked population of 251 females and 87 males, we experimentally examined the effect of reduced reproduction on future growth and reproduction in female plants and examined sexual dimorphism in carbon/nutrient balance. Our results suggest that females of L. benzoin bear greater reproductive costs in terms of both biomass and minerals. These costs were measurable in terms of current biomass and allocation of nitrogen to reproduction, as well as subsequent growth, reproduction, and tissue carbon/nutrient balance. Based upon the results of a fruit-thinning experiment and path analysis, fruit production in 1991 appeared to have direct negative effects on fruit production in 1992, an effect that was not necessarily mediated through effects on plant growth. We discuss our results in the context of other intrinsic and extrinsic factors that can influence growth, reproductive costs, and mortality in this species.     

两种入侵植物与三种本地植物根系特征的比较研究

以菊科2种入侵植物飞机草(Chromolaena odorata (L.)R. M. King & H. Rob)和紫茎泽兰( Eupatorium adenophorum Speng)以及生活型相似的3种本地植物异叶泽兰(Eupatorium heterophyllum DC.)、佩兰(Eupa-torium for...     

Effects of environmental stress and nutlet morph on proportion and within-flower number-combination of morphs produced by the fruit-dimorphic species Lappula duplicicarpa (Boraginaceae)

Phenotypic plasticity in species with heteromorphic diaspores is considered to be a plastic bet-hedging strategy in environmentally fluctuating habitats. The primary aim of this study was to determine the influence of level of abiotic (soil moisture and nutrient availability) and biotic (pure and mixed density) factors on the long-glochid (LN; high dispersal, low dormancy)/short-glochid (SN; low dispersal, high dormancy) nutlet ratio and on nutlet combination of the fruit-dimorphic cold desert winter annual/spring ephemeral Lappula duplicicarpa derived from different nutlet morphs. We hypothesized that stress would decrease the LN: SN ratio. All levels of the four treatments resulted in significant variation in the LN: SN ratio and in the proportion of each nutlet combination. Reproductive biomass varied less than plant mass in plants from both morphs. In favorable environments, the LN: SN ratio and number of SN–3LN and 4LN combinations were relatively high, while in unfavorable environments they were relatively low, thus supporting our hypothesis. Relative allocation to reproductive biomass was significantly negatively correlated with allocation to vegetative biomass. The downward shift that occurred in the LN: SN diaspore ratio in response to stressful growth conditions in Lappula duplicicarpa is assumed to be a bet-hedging strategy.     

Thermal performance curves identify seasonal and site-specific variation in the development of Ecklonia radiata (Phaeophyceae) gametophytes and sporophytes

Rapid ocean warming is affecting kelp forests globally. While the sporophyte life stage has been well studied for many species, the microscopic life stages of laminarian kelps have been understudied, particularly regarding spatial and temporal variations in thermal tolerance and their interaction. We investigated the thermal tolerance of growth, survival, development, and fertilization of Ecklonia radiata gametophytes, derived from zoospores sampled from two sites in Tasmania, Australia, throughout a year, over a temperature gradient (3–30°C). For growth we found a relatively stable thermal optimum at ~20.5°C and stable thermal maxima (25.3–27.7°C). The magnitude of growth was highly variable and depended on season and site, with no consistent spatial pattern for growth and gametophyte size. Survival also had a relatively stable thermal optimum of ~17°C, 3°C below the optimum for growth. Gametophytes grew to single cells between 5 and 25°C, but sporophytes were only observed between 10 and 20°C, indicating reproductive failure outside this range. The results reveal complex effects of source population and season of collection on gametophyte performance in E. radiata, with implications when comparing results from material collected at different localities and times. In Tasmania, gametophytes grow considerably below the estimated thermal maxima and thermal optima that are currently only reached during summer heatwaves, whereas optima for survival (~17°C) are frequently reached and surpassed during heatwaves, which may affect the persistence and recruitment of E. radiata in a warmer climate.     

DIFFERENCES IN BIOMASS ALLOCATION TO REPRODUCTIVE AND VEGETATIVE STRUCTURES OF MALE AND FEMALE PLANTS OF A DIOECIOUS,PERENNIAL HERB,SILENE ALBA (MILLER) KRAUSE

The pattern of biomass allocation of males and females and the sex ratio and growth characteristics of plants from three seed-size classes in Silene alba were investigated in a greenhouse study. Seed size significantly affected adult plant size and flower production of both male and female plants, but there was no significant difference in the proportion of males and females emerging in three seed-size categories. Male and female plants differed in the proportion of total biomass allocated to vegetative and reproductive structures and these differences were consistent across all seed-size categories. Males allocated a greater proportion of their biomass to flowers than did females. Female reproductive effort was dependent upon the percentage of flowers producing mature capsules. Only females with greater than 20% fruit set have a higher reproductive expenditure than males. Consequently, female expenditure is potentially greater than males, but is spread out over a longer portion of the growing season. This difference in the timing of reproductive expenditures by males and females allows females to allocate more biomass to growth during the early flowering period and may therefore account for the common pattern in herbaceous perennial dioecious species in which adult females are larger than adult males.     

Earthworm Communities in the Pineapple (Ananus comosus) and Mixed Fruit Plantations of West Tripura, India

Present studies on the community characteristics of earthworms revealed the occurrence of 11 species of earthworms in the pineapple (Ananus comosus) and 14 species in the mixed fruit plantations of west Tripura (India). While 9 species of earthworms namely Drawida assamensis, Drawida papillifer papillifer, Drawida nepalensis, Kanchuria sp., Metaphire houlleti, Eutyphoeus gigas, Eutyphoeus scutarius, Eutyphoeus comillahnus and Pontoscolex corethrurus are of common occurrence to both the pineapple and the mixed fruit plantations, two and five earthworm species namely Kanchuria sumerianus, Eutyphoeus sp. and Metaphire posthuma, Perionyx excavatus, Lampito mauritii, Amynthus alexandri, Eutyphoeus gammiei are restricted to the pineapple and the mixed fruit plantations respectively. Earthworms were found mostly within 15 cm depth of soils having temperature 25–25.8 °C, moisture 18.8–22.4 %, water holding capacity 26–31.7 % and organic matter content 2.4–4.0 %. Mean earthworm densities (158 ind. m^?2) was significantly higher (p < 0.01, t = 9.67) and biomass (36.67 g m^?2) significantly lower (p < 0.01, t = ?5.98) in the pineapple plantation than the mixed fruit plantation (density 93 ind. m^?2, biomass 56 g m^?2). High density value of earthworms in pineapple plantation is linked with dominance of D. assamensis and high biomass value in mixed fruit plantation was due to the higher relative abundance of larger species like E. gigas, E. scutarius, E. comillahnus and E. gammiei. Compared to the mixed fruit plantation, significantly (p < 0.05) higher index of dominance, lower index of diversity, species richness index and species evenness were recorded in the pineapple plantation.     

The annual pattern of reproduction of Talitrus saltator (Crustacea: Amphipoda: Talitridae)

The reproductive cycle and breeding biology of Talitrus saltator (Montagu), a supralittoral talitrid amphipod, were investigated over a 15 month period on a sandy beach in the Isle of Man. The species is shown to have an annual, univoltine reproductive cycle with a period of high reproductive activity between May and late August. Two generations are present throughout most of the year and the life spans of female and male T. saltator were calculated to be approximately 18 months and 21 months respectively. Initial juvenile growth was rapid, juveniles attaining sexual differentiation within three to four months of hatching. Juvenile growth rates averaged 5–5 mm in 100 days decreasing to 1–3 mm in 100 days after sexual differentiation at around 8.0 mm.
The relative brood size of incubating females was shown to be dependent on at least two factors, the length of the female and the stage of embryological development of the brood.
It is suggested that photoperiod is the major exogenous factor controlling gonadal maturation and the duration of reproductive activity in T. saltator.