Fleshy fungi of grass fields HI. Reaction to different fertilizers and to age of grass turf. Periodicity of fruiting

The fungus flora of an experimental grass field was studied over a ten years period. 48 squares were fertilized with combinations of NPK fertilizers. The nitrogen source was varied over the years. Calcium nitrate was applied in four seasons, ammonium sulphate and calcium ammonium nitrate were each applied in three seasons. Two series of squares had grass turf of different age, in the period ranging from one year to 12 years of age. The 55 species of fungi recorded were clearly divided in a nitrophilous group and a nitrophobous group. In the three first seasons, when an ongoing nitrate programme was continued, the species frequencies in the +N parcels were much higher than in the—N parcels. Most species in the nitrophilous group showed preference for nitrate, and application of ammonium had an almost poisonous effect on a large number of nitrophilous species, including most of the fairy ring formers. Agaricus campestris and two other nitrophilous species reacted positively to potassium. Most of the nitrophobous species were ± attached to moss and to grass debris. A few species had preference for grass turf 1–2 years old while the vaste majority of the fungi were established after 3–5 years.
The fruiting periods of the more common species were found to have a range of several months.     

Fleshy fungi in grass fields. Dependence on fertilization, grass species, and age of field

An experimental field with grass had 48 squares which were treated with combinations of NPK fertilizers. The fungus flora was studied 1978–1980 by numerous yearly observations. A total of 40 species were noted: 36 agarics and 4 gasteromycetes. 24 species were confined to squares where nitrate was applied. 5 of these species were recorded as fairy ring formers. The fairy rings developed exclusively in the +N squares. Some common species grew in both +N and –N squares, while a few species were confined to –N squares. None of the latter group was found in abundance. The squares were divided in parcels sown with 4 species of lawn grasses. Several fungi showed preference for one or two grass species. The field consists of two parts, sown in 1977 and 1972 respectively. The immigration pattern into the new field is described.     

Desiccation tolerance in fully developed embryos of two cicadas, Cryptotympana facialis and Graptopsaltria nigrofuscata

In two Japanese cicadas, Cryptotympana facialis and Graptopsaltria nigrofuscata , with different habitat distributions, fully developed embryos hatch in response to high humidity due to rainfall. Despite the advantage of hatching on rainy days, this trait burdens embryos with an extra period of desiccation until the unpredictable advent of rain. We compared the ability of the fully developed embryos of these cicadas to endure periods of low humidity. Eggs were exposed to a combination of different humidities (43% and 75% relative humidity, RH) and durations (0–15 days), and then transferred to an environment with 100% RH to stimulate hatching. In both species, total hatching rates decreased as duration increased, although there was no significant effect of humidity. In C. facialis , a considerable proportion of the eggs hatched during the desiccation period, and the hatching rate was higher at 75% RH than at 43% RH. After transfer to 100% RH, most hatching occurred within a day regardless of the desiccation level. In G. nigrofuscata , no nymphs hatched during the desiccation periods. However, more eggs required more than a day after transfer to 100% RH to hatch after desiccation at 43% RH than at 75% RH. Consequently, the overall proportion of timely hatching of eggs (eggs hatching within a day of moisture supply) was higher after desiccation at 43% RH in C. facialis , but it was higher after desiccation at 75% RH in G. nigrofuscata . These different physiological responses of the two species may reflect adaptation to habitat dryness.     

Contents of sugars in leaves of drying desiccation tolerant flowering plants, particularly grasses

Sugar complements were analysed in extracts from leaves of desiccation tolerant species in the angiosperm families Cyperaceae, Gesneriaceae, Liliaceae, Poaceae and Velloziaceae. Total sugar content was higher in live air-dry leaves of all desiccation tolerant species (except the grass Eragrostiella nardoides; 22 µmoles/g dw) than in the dead air-dry leaves of the desiccation sensitive grass Sporobolus pyramidalis (36 µmoles/g dw). Sucrose contents rose to high levels (40–98 µmoles/g dw) in live air-dry leaves of all species (except the grass Eragrostiella nardoides in which it rose to only 11 µmoles/g dw) to become the predominant sugar. Glucose and/or fructose contents frequently were lower after leaf drying but usually these were the sugars of next highest contents in live air-dry leaves. Contents of raffinose (that has been postulated to reduce sucrose crystallization) rose to c. 10% of sucrose contents in air-dry leaves of most desiccation tolerant species (but only c. 4% in Tripogon jacquemontii) compared with c. 2% of sucrose contents in the sensitive grass S. pyramidalis. Trehalose (a rare sugar in seed-plants) was present in all but one desiccation tolerant species (Xerophyta villosa) but only in minor amounts. The results are consistent with the views that sugars play a protective role during drying of desiccation tolerant plants in general but that other factors are also involved indesiccation tolerance, that in desiccation tolerant angiospermae sucrose is generally the predominant protective sugar and that raffinose and trehalose may supplement the role of sucrose.     

STUDIES OF THE DIEDERIK CUCKOO CHRYSOCOCCYX CAPRIUS IN THE TRANSVAAL

The migrant Diederik Cuckoo Chrysococcyx caprius was studied on a 72–acre area near the Klein Jukskei River near Johannesburg from 1955–1958. The birds first arrive in early October, after which the males take up territories and call continually until February; subsequent calls up to April are probably made by young birds.
Courtship displays, which involve courtship feeding, and egg-laying follow the birds' arrival by about a month. The Red Bishop Euplectes orix was the species most commonly parasitized, with smaller equal numbers of Cape Sparrows Passer melanurus and Masked Weavers Ploceus velatus . The cuckoos' eggs differ according to the host species and in two cases hatched between ten and 14 days after laying. The chicks normally evict their hosts' offspring on the second or third day after hatching. The fledging period appears to be roughly 19–20 days, and there is a period of post-fledging care lasting between 17 and 38 days, during which the chicks are fed different foods by different host species (grass seeds by bishops; insects of different sizes by weavers and sparrows).
The fact that the eggs and the calls of the chicks vary according to their host species suggest the existence of three separate host-specific strains in this area. The incidence of brood parasitism in Red Bishops' nests varied from 7–50% and averaged 25%.     

Coefficients of digestibility and nutritional values of geophytes and tubers eaten by southern African mole-rats (Rodentia: Bathyergidae)

Subterranean rodents have high energy requirements when they are excavating their burrows. This study investigates the energy available to, and the efficiency with which it can be extracted by, four species of bathyergid mole-rats fed natural diets ranging from the underground storage organs of geophytes to grass roots and leaves.
The digestibility coefficients of geophytes ranged from 53% for the fibrous tuber of the gemsbok cucumber to 95–7% for corms and bulbs. One species, Bathyergus suillus whose diet consists of over 80% grass, had a digestibility coefficient of 87% on an all grass diet.
All species had similar coefficients of digestibility of > 90% when fed on a uniform diet of sweet potato.
Bulbs and corms had a low fibre content (3–3–4%), high calorific value (15–16kJ/g) and high digestibility coefficients (95–7–96%) and on this diet the mole-rats maintained their body mass. Food of lower digestibility tended to have a high fibre content (8–2–45%) and, with the exception of B. suillus , although the mole-rats consumed a greater quantity of food, they lost mass. The sweet potato had a low fibre content (4–1 %) but was energetically very similar to bulbs and corms (15–5 kJ/g).
Geophytes which have low fibre contents are generally small (1–20 g), whereas geophytes with high fibre contents are much larger (30–2000 g) and often occur in more arid zones.     

Enzyme Variation of Eimeria arizonensis from Peromyscus truei and P. boylii

ABSTRACT. Cricetid rodents, Peromyscus truei and P. boylii , were inoculated with sporulated oocysts of Eimeria arizonensis collected from wild P. truei maintained in the lab. In P. truei the prepatent period was 4–5 days, the patent period was 9–11 days, and sporulated oocysts were 21.5 × 25.0 (20–23 × 24–26) μm with sporocysts 7.7 × 12.0 (6–8 × 10–13) pm. In P. boylii the prepatent period was 6–7 days, the patent period was 8–9 days, and sporulated oocysts were 20.1 × 23.2 (18–22 × 21–24) pm with sporocysts 6.8 × 10.0 (5–8 × 9–12) pm. Sporulated oocysts from both host species were used in direct side-by-side comparison of isozyme banding patterns using protein electrophoresis. The parasite has polytypic loci for leucine aminopeptidase (LAP), lactate dehydrogenase (LDH), and 6-phosphogluconate dehydrogenase (6-PGD). In oocysts from P. truei , LAP showed one band with fast migration and LDH and 6-PGD each showed two bands, one with fast and one with slow migration. In oocysts from P. boylii , LAP and LDH each had one band with slow migration and 6-PGD had one band with moderate migration. Oocysts of E. arizonensis collected from P. boylii were used to inoculate P. truei. The prepatent and patent periods, structural measurements, and isozyrne banding patterns of the resultant oocysts were the same as those from P. truei when inoculated with oocysts from P. truei.     

Life history of the oligochaete Enchytraeus coronatus (Annelida, Enchytraeidae) in agar culture

Abstract. Life-history attributes and the reproductive biology of Enchytraeus coronatus (Oligochaeta, Enchytraeidae) were studied in agar cultures, as a basis for using this species in toxicity tests and other experimental studies. The use of agar allows daily examination of the behavior, reproduction, and mortality of the worms. At 20°C, E. coronatus had a generation time of 21–22 days and an embryonic period of 7–10 days. Hatch rate was high (>80%) and worms became sexually mature 8–10 days after hatching. Cocoon production and number of eggs per cocoon were positively correlated. Mortality in the first stages of the life cycle (embryonic period and first week after hatching) was about 38%. Three different periods of cocoon production were distinguished: a period characterized by a regular increase in the number of cocoons produced (weeks 4–9), a period of production at a constant high rate of ∼5 cocoons per week (weeks 10–20), and a period of decline in production rate (weeks 21–32), down to a mean value of 1.6 cocoons per adult in the last week. This study showed that synchronized agar cultures of cohorts can provide adults for long-term experimental tests, with the age for optimum reproduction being 8–20 weeks.     

Physiological history may mask the inherent inducible desiccation tolerance strategy of the desert moss Crossidium crassinerve

Shoots of bryophytes collected in the desiccated state from the field are likely to be hardened to desiccation tolerance (DT) to varying degrees. To account for this, most studies on DT include a relatively short deacclimation period. However, no study has experimentally determined the appropriate deacclimation time for any bryophyte species. Our purposes are to (i) determine if ‘field effects’ are biologically relevant to DT studies and how long a deacclimation period is required to remove them; and (ii) utilise field versus cultured shoot responses within the context of a deacclimation period to elucidate the ecological strategy of DT. Our hypothesis (based on an extensive literature on DT) is that a deacclimation period from 24 to 72 h should be sufficient to eliminate historical stress effects on the physiology of the shoots and allow an accurate determination of the inherent ecological DT strategy (constitutive or inducible). We determined, however, using chlorophyll fluorescence and visual estimates of shoot damage, that field‐collected shoots of the desert moss Crossidium crassinerve required an experimental deacclimation period of >7 days before field effects were removed, and revealed an ecological DT strategy of inducible DT. If the deacclimation period was <6 days, the shoot response conformed to an ecological strategy of constitutive protection. Thus the presence of field effects can obscure the ecological strategy of desiccation tolerance exhibited by the species, and this translates into a need to re‐evaluate previous mechanistic and ecological studies of desiccation tolerance in plants.     

Desiccation resistance of bacteria isolated from an air-handling system biofilm determined using a simple quantitative membrane filter method

Twelve strains of bacteria recovered from a biofilm growing on cooling coil fins in an air-handling system, representing recognized members of the coil fin biofilm community, were assessed for their desiccation resistance. A quantitative membrane filter method was used to assess desiccation resistance over a 24 h period. The method proved to be a reliable and inexpensive means of quantitatively assessing desiccation resistance in bacterial isolates. Five pink-pigmented budding rod (PPBR) isolates, related to Methylobacterium , were resistant to desiccation over the test period (47–100% of original viable cfu were recoverable on R3A agar after 24 h desiccation). Methylobacterium -like PPBRs represented the dominant culturable members of the coil fin biofilm community. An unidentified Gram-negative filamentous rod was also somewhat desiccation-resistant (45% of original viable cfu were recoverable on R3A agar after 24 h desiccation). The remaining six strains tested, three Gram-negative isolates and three Gram-positive isolates, were sensitive to desiccation with only 0–11% of the original viable cfu being recoverable on R3A agar after 24 h desiccation. Since the coil fin biofilm is subjected to extended periods of desiccation, the results suggest that desiccation resistance is at least partly responsible for the dominance of the coil fin biofilm community by the Methylobacterium -like PPBR.     

Reproductive biology, development, and planula behavior in the Caribbean gorgonian Pseudopterogorgia elisabethae

Abstract. The reproductive biology, development, and planula behavior of the gorgonian Pseudopterogorgia elisabethae were studied at 2 sites in the Bahamas between 1996 and 2001. Colonies were gonochoric, and females brooded planulae on the colony surface. Gonads were observed only in colonies 18 cm high or larger. Spawning was asynchronous within and between sites but was concentrated 2–10 days after the new moons from late November through early January. Fertilized eggs developed into planulae over 1–2 days and the planulae remained attached to the surface of the female colony for an additional 2–4 days. Planulae were negatively buoyant and field observations suggest that larvae may settle within tens of meters of the maternal colony. P. elisabethae is harvested for natural products, and information on the reproduction of this commercially important species is crucial to the understanding of its population biology and to the development of management plans for the conservation of the species.     

Seasonal abundance of macropterous Nilaparvata lugens and Sogatella furcifera based on presumptive macroptery in fifth-instar nymphs

Abstract. 1. The seasonal changes in abundance of macropterous N. lugens (Stal) and S. furcifera (Horvath) (Homoptera: Delphacidae) are described based on observed numbers of adults and presumptive macroptery in fifth-instar nymphs occurring in rice crops in the Philippines.
2. Percentage presumptive macroptery in fifth-instar nymphs was correlated with nymphal density over the range of 0–20 nymphs per hill for females of both species and 5–20 nymphs per hill for male N. lugens.
3. Lunar phase had no effect on wingmorph expression in either species.
4. Comparison of the percentage macroptery in fifth-instar nymphs with subsequent percentage macroptery in N. lugens adults for one season showed net emigration occurred from 60 DAT (days after transplanting) to harvest except for a period of net immigration lasting 7–10 days at approximately 95 DAT for both sexes.     

Observations on the larval development of Mystus macvopterus (Bleeker): Bagridae

From June to July 1988, larvae of Mystus macropterus (Bleeker) were obtained by artificial propagation of spawners collected from the Jialing River, China. Larvae grown in water temperatures ranging from 26 to 29°C were fully developed at approximately 20 days. The newly-hatched larvae measured 6.0–7.5 mm t.l. , exceeding the dimensions of any known newly-hatched larvae of freshwater catfishes indigenous to China. Five days after hatching, when the larvae were 11.4 mm t.l. and the prolarval stage was complete, exogenous feeding commenced. Twelve days after hatching, at 18.4 mm t.l. , the yolk sac disappeared, organogenesis was almost complete and the juvenile period began. At 20 days post-hatching, at 23.0 mm t.l. , the lateral line system had formed and the juveniles resembled the adults with respect to all external features, which signalled the end of thejuvenile period. Comparison of the larval development in eight species ofeconomic freshwater catfishes shows that the most significant aspect of the larval development of M. macropterus is the sustained (6–7 days) mixed nourishment period and the early differentiation of organs, which enhances the survival rate of the larvae.     

Pasture seed dynamics in a dry monsoonal climate,II The effect of water availability,light and temperature on germination speed and seedling survival of Stylosanthes humilis and Digitaria ciliaris

Environmental factors affecting speed of germination and survival of naturally occurring seed of the legume Stylosanthes humilis and the grass Digitaria ciliaris were studied. Previous studies on the seedbed environment had shown that germination speed, defined as the proportion of seeds capable of germinating in the first 12 h period, was likely to be the most relevant laboratory measurement. Ten studies were conducted to compare species performance and to devise a standard technique for the measurement of germination speed under laboratory conditions. For S. humilis, the level and duration of submergence in water in the germination test had a large effect on germination speed (from 0–70% in 12 h). The absence of light delayed germination (7% in 12 h compared to 52% under light), but did not prevent complete germination over 7 days. Optimum temperature was 25°C with a decrease to 0% at 30°C. A standard technique was developed for measuring potential germination speed which gave reproducible results allowing differences in seed lots to be described. D. ciliaris seeds sampled just prior to field germination in the early storm period were less sensitive to environmental control. Temperature optimum for germination decreased from 40 to 30°C with the duration of the germination test. Seeds sampled at the time of seed dispersal (early dry season) had a high fraction (80%) requiring light for germination but this requirement had been lost by the early storm period. Investigations on the role of leaching (water movement) showed that long periods of water movement (12–18 h) increased the speed of germination of both species and in the case of S. humilis overcame environmental blocks to rapid germination (absence of light or 30°C temperature). Root elongation rates in S. humilis were not greatly affected by temperature over the range of seedbed temperatures when moisture is available (25–40°C) in the field. However, D. ciliaris was delayed in development at 25°C, the most likely overnight surface soil temperature. D. ciliaris was more susceptible to death by desiccation once germination had occurred compared to S. humilis. In both species seedling death due to desiccation increased with stage of development. The better relative performance of S. humilis in the germination-establishment phase of the life cycle, which had been observed in a previous study, could be explained by a qualitative comparison of the species' attributes. This suggested that D. ciliaris was more likely to germinate at rainfall events following which there was a greater chance of seedling death     

科尔沁沙地15种禾本科植物种子萌发特性比较

在实验室条件下,观测了科尔沁沙地乌兰敖都地区禾本科植物当年新采种子的萌发特点．15种植物中,披碱草、糙隐子草、冠芒草、大油芒、芦苇、虎尾草、野古草、狼尾草的发芽率超过80％,水稗草、牛鞭草、虱子草、狗尾草的发芽率不足10％．1～3d开始发芽的植物有大油芒、画眉、芦苇、虎尾草、披碱草、冠芒草、毛马唐、糙隐子草．超过10d基本不发芽的植物包括狗尾草、虱子草、牛鞭草．发芽持续期小于10d的植物包括毛马唐、水稗草、芦苇、画眉草、大油芒;发芽持续期21～30d的植物有披碱草、冠芒草．发芽种子超过总发芽种子的50％需要天数为虎尾草2d,芦苇3d,大油芒4d,披碱草5d,糙隐子草5d,野古草7d,冠芒草7d,狼尾草10d．与英国Sheffield地区相比,乌兰敖都地区一年生禾草发芽率低的所占比重更大,发芽更为缓慢;乌兰敖都地区多年生禾草的发芽率差别很小,但发芽更为缓慢．杂草植物萌发的风险分摊能力相对明显,因此抗干扰能力相对较强．     

Diapause duration, survival in relation to desiccation and egg-pod morphology of the Senegalese grasshopper, Oedaleus senegalensis

Abstract. The Senegalese grasshopper, Oedaleus senegalensis (Krauss) (Orthoptera: Acrididae), is periodically a devastating pest of subsistence crops in the sahelian zone of West Africa.Egg diapause has been suggested as an important component of the mechanism acting to generate outbreaks and therefore diapause duration, egg survival in relation to desiccation and egg-pod morphology were investigated in this study.
Three months after oviposition, 50% of initially diapausing egg pods maintained in the laboratory exhibited 'partial emergence' and produced hoppers.No difference in diapause duration was evident between egg pods maintained at a constant 30 ± 1°C and those maintained under alternating temperature conditions of 23 ± 1°C and 35 ± 1°C.Laboratory maintained eggs showed significant variation in diapause duration with diapause lasting between 2 months and 4 years.Diapause duration was shorter in the field with only c. 1.4% of eggs remaining in diapause after a single dry season (6–7 months).Survival of eggs in relation to desiccation was high in the field and low in the laboratory, and field eggs lost only c. 20% of their body weight over the dry season.Survival of diapausing and non-diapausing egg pods in the laboratory was similar, indicating that diapause in this species is primarily a mechanism for preventing emergence at an inappropriate time of year, rather than conferring any additional resistance to desiccation.Egg pods oviposited under diapause-inducing conditions (LD 14:10 h, 25°C) were significantly shorter than those laid under non-diapausing conditions (LD 10:14 h, 40°C).These results are discussed both in relation to possible O.senegalensis 'bet-hedging' strategies and to the probable mechanism operating behind major outbreaks of this species.     

Laboratory spawning, larval development, and metamorphosis of the limpets Lottia digitalis and Lottia asmi (Patellogastropoda, Lottiidae)

Abstract. This study describes and compares laboratory spawning, larval development, and metamorphosis in the patellogastropod limpets Lottia digitalis and Lottia asmi. Both species were dioecious and freely spawned their gametes, which were fertilized externally. Eggs from L. digitalis and L. asmi averaged 155 and 134 μm in diameter, respectively. Early cleavage patterns were typical of other patellogastropods. Swimming trochophore larvae had developed ∼ 15 hours after fertilization, and ultimately developed into lecithotrophic veliger larvae that reached metamorphic competence at 5.25–5.5 days after fertilization (13°C). Food particles were frequently visible in the gut of newly metamorphosed individuals one day after settlement, and adult shell growth was typically initiated within 2–4 days of settlement. Small egg size in L. asmi , relative to other eastern Pacific lottiids, may be directly related to the need for high fecundity in this small-bodied species; however, developmental information is available for relatively few lottiid species. Because broadcasting lottiids do not secure egg masses in safe microhabitats for development, this reproductive mode may have been conducive to their ecological radiation into novel habitats.     

The lack of control of water loss in micropropagated plants is not related to poor cuticle development

To assess if cuticular transpiration could contribute significantly to the high rates of water loss often observed in micropropagated plants after transfer to the nursery, it was tested whether adaxial cuticular water permeance (P) of leaves grown in vitro was higher than that of leaves grown ex vitro. For four species of micropropagated plants with hypostous leaves ( Delphinium elatum hybrid, Doronicum hybrid, Hosta sieboldiana var. elegans, Rodgersia pinnata ), P was determined with two independent techniques which gave similar results. Minimum adaxial overall conductance was measured with the same methods for a Heuchera hybrid which had amphistomatous leaves. Leaves of all species except Heuchera lost 36–65% of their original weight within 25 min after excision. Detached leaves whose abaxial surfaces had been coated lost only 25–38% of their original weight within 5–9 h. Permeances (P) were between 1 × 10⁻⁵ m s⁻¹ and 1 × 10⁻⁴ m s⁻¹, which was within the range of typical values found with leaves grown ex vitro. From these results and a critical assessment of the literature it is concluded that there is no evidence that P of micropropagated plants was high enough to contribute significantly to the desiccation problem at the transfer stage.     

Survival of Schismus arabicus seedlings exposed to desiccation depends on annual periodicity

Schismus arabicus, a desert annual grass, is one of the most common pasture annuals in the deserts of Israel and Asia. S. arabicus exhibits a unique set of adaptations and survival strategies, which enable it to germinate, develop and produce seeds even in years with annual rainfall of less than 100 mm. The current study examined whether an annual rhythm exists in the survival ability of S. arabicus seedlings exposed to desiccation. Our results indicate that survival of S. arabicus seedlings after six different periods of 7 to 42 days of desiccation depended on the month of germination of the caryopses (seeds). Seed germination was 80–100% in all experiments, regardless the month of germination; however, seedlings that germinated in different months varied in their root and shoot elongation rates. None of about 2,500 seedlings that germinated in July (in each of the 4 years) survived the desiccation treatment. The percentages of surviving seedlings in each month of June from 2002 to 2005 were less than 40%. In contrast, over 80% of the seedlings that germinated in each of the months of December and January survived after the desiccation periods of 7–42 days. Seedlings that survived were transferred to 5 L soil pots in which the seedlings developed into mature plants, completed their life cycle and produced seeds that germinated well. The current study demonstrated a novel phenomenon indicating that seedling survival in plants may depend on an annual periodicity according to the date of germination.     

Effect of burning and mowing on grass and forb diversity in a long‐term grassland experiment

Abstract. Disturbance may be an important determinant of plant community composition and diversity owing to its effects on competitive interactions, resources, dominance and vigour. The effect of type, timing and frequency of disturbance on grass and forb species richness was examined using data from a long‐term (> 50 yr) grassland burning and mowing experiment in KwaZulu‐Natal, South Africa. Grass species richness declined considerably (> 50%) in the absence of disturbance, whereas forb species richness was unaffected. Annual burning in sites not mown in summer tended to increase grass species richness relative to triennial burning (22% increase) with the reverse being true in sites mown twice in summer (37% decline). Forb species richness declined by 25% in sites mown twice in summer relative to sites mown in early summer only. Disturbance was necessary to achieve maximum grass species richness presumably by removing litter and increasing the availability of light. The interaction of time of mowing in summer (early versus late) and time of burning during the dormant period (spring versus winter) had the most dramatic effect on species richness. Time of burning had no effect on richness in sites mown in early summer, but winter burning resulted in a dramatic decline (27–42%) in richness in sites mown in late summer. This effect may be related to possible greater soil desiccation with this combination of disturbances.