High Rainfall Years Research Articles

Assessing effect of rainfall on rate of alien shrub expansion in a southern African savanna

Understanding the environmental factors governing the spread of alien shrubs is crucial for conserving biodiversity. In the semi-arid savannas of Africa, alien shrub invasion often occurs simultaneously with native shrub encroachment but climate-dependent differences in encroachments of native and alien shrubs have never been properly quantified. A combination of historical aerial photographs and field measurements was used to compare the spread of the invasive shrub Lantana camara L. with that of native encroaching shrubs over a 31-year period in a protected semi-arid savanna in Zimbabwe, southern Africa. We tested whether the response of this invasive alien shrub to rainfall differs from that of native shrub encroachers. Both the invasive shrub L. camara and native encroaching shrubs spread significantly faster during high rainfall years than in dry years. However, the response of L. camara to annual rainfall was stronger than the response of native encroaching shrubs. During years of above-average rainfall, the mean annual rate of spread of L. camara was at least twice that of native shrub encroachers, whereas in other years natives spread at the same rate as the alien shrub. This is a novel finding suggesting that in water-limited savannas, pulses in rainfall may accelerate the spread of some invasive alien species.

Persistence and productivity of phalaris (Phalaris aquatica) germplasm in dry marginal rainfall environments of south-eastern Australia

Perennial grasses have production and environmental benefits in areas of southern Australia typified by the mixed farming zone of southern New South Wales (NSW). The perennial grass phalaris (Phalaris aquatica L.) is widely used in southern Australia; however, it would find more use in the mixed farming zone if its persistence in marginal rainfall areas (450–500 mm average annual rainfall) were improved. We evaluated a range of germplasm (n = 29) including wild accessions, lines bred from these, and existing cultivars for persistence and production at three sites in a summer-dry area of southern NSW with 430–460-mm average annual rainfall. Two sites were used over 4 years and the third site over 5 years. Summer dormancy, maturity time and seedling growth were also assessed. Analysis of genotype × environment interaction employing factor analytic models and accounting for spatial and temporal correlations indicated that changes in persistence occurred mainly over time rather than between sites. Ranking changes occurred in the dry establishment phase of the experiment and during a severe final summer drought, with few changes occurring in the intervening high-rainfall years. Lines that survived the establishment phase best had vigorous seedlings and earlier maturity, whereas those surviving the final summer best were earlier maturing and higher in summer dormancy with high winter-growth activity. Some later maturing lines within the higher summer dormancy group were less persistent. Some accessions from North Africa were the most persistent; also, populations bred from these and other more persistent accessions generally persisted and produced better than cultivars used presently. However, present cultivars were capable of high yield in the higher rainfall years. We suggest that persistence of higher summer dormancy cultivars over very dry years could be improved by selecting for earlier maturity time.

Inter-annual Variability of Soil Respiration in Wet Shrublands: Do Plants Modulate Its Sensitivity to Climate?

Understanding the response of soil respiration to climate variability is critical to formulate realistic predictions of future carbon (C) fluxes under different climate change scenarios. There is growing evidence that the influence of long-term climate variability in C fluxes from terrestrial ecosystems is modulated by adjustments in the aboveground–belowground links. Here, we studied the inter-annual variability in soil respiration from a wet shrubland going through successional change in North Wales (UK) during 13 years. We hypothesised that the decline in plant productivity observed over a decade would result in a decrease in the apparent sensitivity of soil respiration to soil temperature, and that rainfall variability would explain a significant fraction of the inter-annual variability in plant productivity, and consequently, in soil respiration, due to excess-water constraining nutrient availability for plants. As hypothesised, there were parallel decreases between plant productivity and annual and summer CO2 emissions over the 13-year period. Soil temperatures did not follow a similar trend, which resulted in a decline in the apparent sensitivity of soil respiration to soil temperature (apparent Q10 values decreased from 9.4 to 2.8). Contrary to our second hypothesis, summer maximum air temperature rather than rainfall was the climate variable with the greatest influence on aboveground biomass and annual cumulative respiration. Since summer air temperature and rainfall were positively associated, the greatest annual respiration values were recorded during years of high rainfall. The results suggest that adjustments in plant productivity might have a critical role in determining the long-term-sensitivity of soil respiration to changing climate conditions.

Spatio‐temporal patterns of evapotranspiration from groundwater‐dependent vegetation

AbstractUnderstanding hydrological processes in water‐limited systems requires consideration of temporal and spatial vegetation water use patterns at the landscape scale. We used data derived from the MODerate Resolution Imaging Spectroradiometer (MODIS) satellite instrument and interpolated climate data covering a ten‐year period to contrast the spatio‐temporal patterns of actual evapotranspiration (AET) from known phreatophytic and non‐phreatophytic vegetation overlying a large superficial aquifer. We assessed shallow to deeper groundwater habitats and compared AET responses to seasonal and inter‐annual variation in precipitation. Overall, vegetation in shallow groundwater habitats had higher AET rates during the growth season (spring and summer) than vegetation growing in deeper groundwater habitats, suggesting that the former was not physiologically constrained by water deficit. Vegetation in areas of consistently high (ground‐)water availability maintained higher AET, reaching a peak of 95 mm in mid‐summer. In contrast, plantation maritime pines had the highest AET rates at deep groundwater habitats. Inter‐annual variability in AET correlated with rainfall and AET rates peaked two months after the majority of effective rainfall had fallen. During low rainfall years, maximum AET peaked one month earlier relative to higher rainfall years. The results of this study suggest that remote sensing of AET can give a conditional indication of where groundwater is important in supporting vegetation and can be a valuable tool in identifying management focus areas where vegetation is variably sensitive to water deficit. Copyright © 2016 John Wiley & Sons, Ltd.

Spatial and temporal estimation of soil loss for the sustainable management of a wet semi-arid watershed cluster.

The ungauged wet semi-arid watershed cluster, Seethagondi, lies in the Adilabad district of Telangana in India and is prone to severe erosion and water scarcity. The runoff and soil loss data at watershed, catchment, and field level are necessary for planning soil and water conservation interventions. In this study, an attempt was made to develop a spatial soil loss estimation model for Seethagondi cluster using RUSLE coupled with ARCGIS and was used to estimate the soil loss spatially and temporally. The daily rainfall data of Aphrodite for the period from 1951 to 2007 was used, and the annual rainfall varied from 508 to 1351 mm with a mean annual rainfall of 950 mm and a mean erosivity of 6789 MJ mm ha(-1) h(-1) year(-1). Considerable variation in land use land cover especially in crop land and fallow land was observed during normal and drought years, and corresponding variation in the erosivity, C factor, and soil loss was also noted. The mean value of C factor derived from NDVI for crop land was 0.42 and 0.22 in normal year and drought years, respectively. The topography is undulating and major portion of the cluster has slope less than 10°, and 85.3% of the cluster has soil loss below 20 t ha(-1) year(-1). The soil loss from crop land varied from 2.9 to 3.6 t ha(-1) year(-1) in low rainfall years to 31.8 to 34.7 t ha(-1) year(-1) in high rainfall years with a mean annual soil loss of 12.2 t ha(-1) year(-1). The soil loss from crop land was higher in the month of August with an annual soil loss of 13.1 and 2.9 t ha(-1) year(-1) in normal and drought year, respectively. Based on the soil loss in a normal year, the interventions recommended for 85.3% of area of the watershed includes agronomic measures such as contour cultivation, graded bunds, strip cropping, mixed cropping, crop rotations, mulching, summer plowing, vegetative bunds, agri-horticultural system, and management practices such as broad bed furrow, raised sunken beds, and harvesting available water using farm ponds and percolation tanks. This methodology can be adopted for estimating the soil loss from similar ungauged watersheds with deficient data and for planning suitable soil and water conservation interventions for the sustainable management of the watersheds.

Space–time variability of Indonesian rainfall at inter-annual and multi-decadal time scales

We investigated the space–time variability of wet (Nov–Apr) and dry (May–Oct) season rainfall over Indonesia, using monthly gridded rainfall data from the University of East Anglia Climatic Research Unit covering the period 1901–2012. Three complimentary techniques were employed—(1) principal component analysis to identify the dominant modes of variability, (2) wavelet spectral analysis to identify the spectral characteristics of the leading modes and their coherence with large scale climate variables and (3) Bayesian Dynamical Linear Model (BDLM) to quantify the temporal variability of the association between rainfall modes and climate variables. In the dry season when the Inter Tropical Convergence Zone (ITCZ) is to the north of the equator the leading two principal components (PCs) explain close to 50 % of the rainfall. In the wet season the ITCZ moves to the south and the leading PCs explain close to 30 % of the variance. El Nino Southern Oscillation (ENSO) is the driver of the leading modes of rainfall variability during both seasons. We find asymmetry in the teleconnections of ENSO to high and low rainfall years in the dry season. Furthermore, ENSO and the leading PCs of rainfall have spectral coherence in the inter-annual band (2–8 years) over the entire period of record and in the multi-decadal (8–16 years) band in post-1980 years. In addition, during the 1950–1980 period the second mode of variability in both seasons has a strong relationship with Pacific Decadal Oscillation. The association between ENSO and the leading mode of Indonesian rainfall has strengthened in recent decades, more so during dry season. These inter-annual and multi-decadal variability of Indonesian rainfall modulated by Pacific climate drivers has implications for rainfall and hydrologic predictability important for water resources management.

Patterns in arthropod abundance and biomass in the semiarid thorn scrub of Bosque Fray Jorge National Park, north-central Chile: A preliminary assessment

In 2003, we initiated a sampling protocol for arthropods as part of long-term field experiment in a semiarid thorn scrub community in north-central Chile. We utilized pitfall and Malaise traps to sample terrestrial and volant arthropods, respectively. Inventories were conducted for 4 days and nights monthly. We posited that arthropod abundance and biomass would track environmental changes such as high rainfall often due to El Niño Southern Oscillations (ENSOs). Peaks in both abundance and biomass for terrestrial and volant arthropods were in similar months (spring–early summer; August–November); arthropods also tracked high rainfall years in 2004, 2006, and 2011, due mostly to increases in a few dominant groups, i.e., tenebrionid beetles (Coleoptera) in terrestrial sampling, and moths (Lepidoptera: Noctuidae, microlepidoptera) in aerial sampling. However, the same groups increased dramatically in 2008 which was a below-average rainfall year. Numerical decreases in late summer-fall months (January–April) were more abrupt for terrestrial arthropods than for volant ones. Both terrestrial and volant arthropods reached their lowest levels in winter months (June–July). Some evidence suggests long-term shifts in the composition of volant taxa. Arthropods likely are important prey items for insectivorous reptiles (i.e., lizards), birds, and an insectivorous small mammal, the elegant mouse opossum (Thylamys elegans), and future efforts are being directed towards examining the evidence for correlated changes in those consumers with arthropod abundance and biomass.

Ecohydrology of groundwater‐dependent grasslands of the semi‐arid Horqin sandy land of inner Mongolia focusing on evapotranspiration partition

AbstractThe Horqin sandy steppe is an ecosystem where groundwater‐dependent grasslands are main components. To study the dynamics of soil water and evapotranspiration, and its partition into transpiration and soil evaporation, the SIMDualKc model was applied to two sites in the Agula eco‐hydrological study area, Inner Mongolia, China. This model adopts the dual crop coefficient approach to compute daily crop evapotranspiration (ETc) and uses a parametric function to compute capillary rise from a shallow watertable. The application refers to three years of field observations, 2008 with high rainfall and higher watertable, 2009 with low rainfall and lower watertable, and 2011 with average rainfall and watertable conditions. Model calibration and validation were performed comparing simulated against observed soil water content throughout the vegetation seasons, with regression coefficients close to 1.0 and small root mean square errors (RMSE < 0.013 cm3 cm−3). The groundwater contribution represented 41–47% of the actual ETc in the higher rainfall year and 56–59% in the dry year, which clearly shows the role of groundwater in sustaining grasslands in the Horqin steppe. The ratio between transpiration and actual ETc ranged 88 to 94%, which is much higher than observations in other grasslands because capillary rise contributes to extraction by crop roots, not to soil evaporation. Simulations relative to lowering the watertable show that groundwater contribution decreases up to 25% for a dry year with a consequent decrease of transpiration of 24%. Hence, there is the need for developing appropriate groundwater protection measures to preserve the Horqin landscape. Copyright © 2015 John Wiley & Sons, Ltd.

Field Evaluation of Cocksfoot, Tall Fescue and Phalaris for Dry Marginal Environments of South‐Eastern Australia. 1. Establishment and Herbage Production

AbstractNewly developed candidate cultivars of cocksfoot (Dactylis glomerata L.), phalaris (Phalaris aquatica L.) and tall fescue (Festuca arundinacea Schreb. = syn. L. arundinaceum (Schreb) Darbysh.) were evaluated over four years for persistence and productivity against current commercial cultivars in small plots at five locations selected for lower and less reliable rainfall and difficult soils (low pH and high Al) in south‐eastern Australia known to be marginally too dry for these grass species. The five locations were ‐ representing summer dominant rainfall, Inverell, in northern New South Wales (NSW); ‐ representing uniform rainfall; Trungley Hall, (medium rainfall), and Beckom (lower rainfall) both in southern NSW; and; representing a winter dominant pattern ‐ Eversley, (higher rainfall), and Bealiba, (lower rainfall), in central Victoria. The objective was to determine if the new candidate cultivars were more likely to persist and to be productive than current commercial cultivars. The study showed that most phalaris and cocksfoot treatments were highly productive in high rainfall years at one or both sites in southern NSW. However, all treatments had become much less productive by the end of the experimental period due to plant loss under hot, dry conditions in the final summer. At Bealiba in central Victoria, cocksfoot was the most productive species with several cocksfoot treatments of both subsp. hispanica and subsp. glomerata still present at the final harvest despite a hot and dry final summer‐autumn. Tall fescue was the most productive species in the two higher rainfall environments (Inverell, Eversley) although most treatments of all species performed well at those sites. Continental tall fescues were more productive on average than Mediterranean tall fescues at the strongly acidic Eversley site. As a result of this work, two of the new cocksfoot candidates (Moroccan Fine and AVH48 Selection) and one of the tall fescue candidates (Summer Active 1) have been licensed for commercial development and release.

Response of Aquatic Invertebrates to Ecological Rehabilitation of Southeastern USA Depressional Wetlands

We assessed aquatic invertebrate response to ecological rehabilitation treatment in 20 depression wetlands on the Savannah River Site, South Carolina, USA. All wetlands had been ditched for 50+ years. Sixteen of the 20 wetlands received rehabilitation treatment, and four wetlands remained untreated as a control group. Treatment included logging of all trees, plugging drainage ditches, and planting wetland trees and grasses. Hydroperiods were consequently extended in most of the treatment wetlands. As part a larger study, we sampled macroinvertebrates and microcrustaceans during the pre-habilitation (1998–2000) and rehabilitation (2001–2003) phases. Our study spanned 2 years of high rainfall (1998 and 2003) and 4 years of low rainfall (1999–2002). Samples were collected bimonthly from any wetlands holding water. Macroinvertebrate assemblages in treatment wetlands in 2003 had changed from previous years (1998–2002) and compared to control wetlands (1998–2003), with abundances of Baetidae, Coenagrionidae, Dytiscidae, Chironomidae, and Chaoboridae driving variation. For microcrustaceans (Copepoda and Branchiopoda, including Cladocera, Anostraca and Laevicaudata), assemblage composition and species richness responded mainly to hydrologic conditions. Rehabilitation efforts in these wetlands induced diverse and abundant invertebrate communities to develop, but some responses appeared opportunistic; several taxa that benefitted were not typical residents of depressional wetlands in the region.

Impacts of agricultural water interventions on farm income: An example from the Kothapally watershed, India

Agricultural water interventions (AWI), e.g. in-situ soil and water conservation strategies, irrigation, and damming of rivers to increase groundwater recharge, have been suggested as important strategies to improve yields in tropical agriculture. Although the biophysical implications of AWIs have been well investigated, the coupling between the biophysical changes and the economic implications thereof is less well understood. In this study we translate the results from a hydrological model, SWAT, on crop yields for different cropping systems with and without agricultural water interventions, to hypothetical farm incomes for a watershed, Kothapally, located in Andhra Pradesh, India. It was found that on average, AWI significantly improved farm incomes by enabling the cultivation of a high value crop during the monsoon season (cotton), supplementary irrigated to bridge dry spells and replacing a traditional crop (sorghum), and also by enhancing the capacity to produce dry season, fully irrigated vegetable crops, in this case exemplified by onion. AWI combined with cotton resulted in more than a doubling of farm incomes compared to traditional sorghum-based systems without AWI during normal and wet years (i.e. for 75% of the years). Interestingly, we observed that the difference between the AWI system and the no intervention system was larger during years of high average rainfall compared to dry years. It was also found that access to irrigation was more important for farm income than crop choice and AWI per se, and thus farms with access irrigation benefitted more from AWI compared to farmers lacking access to irrigation. In conclusion, we suggest that in order to assess equity aspects in terms of farm income generation following the implementation of an AWI project, there is a need for income analyses at the farm level, since income estimates at the watershed level may mask important differences in economic benefits between farms.

Mile-a-minute weed (Persicaria perfoliata) and weevil (Rhinoncomimus latipes) response to varying moisture and temperature conditions

The combined effects of herbivory and water stress on growth and reproduction of mile-a-minute weed (Persicaria perfoliata (L.) H. Gross) were investigated in greenhouse trials over two years, with well-watered or water-limited plants either exposed or not exposed to herbivory by the mile-a-minute weevil (Rhinoncomimus latipes Korotyaev). Moisture limitation and weevil herbivory significantly reduced the number of seeds produced by P. perfoliata, with the fewest seeds produced when both factors were present. Seed weight was reduced by moisture limitation and weevil herbivory the second year, and seed viability was reduced by herbivory both years. Plant biomass was lower both years under conditions of water limitation, with an additional effect of herbivory the second year. Well-watered plants the second year also produced substantially more weevils than water-limited plants by the end of the season. Results are consistent with field observations suggesting that years of high rainfall allow resurgence of P. perfoliata plant populations that were previously suppressed by R. latipes. An additional environmental chamber trial assessed the interaction between the weed and weevil at two different temperatures. Here, plant mortality occurred only at the higher temperature with weevil herbivory, suggesting that herbivory has a greater negative effect on P. perfoliata under warm conditions. Additional studies on temperature effects are needed for a more complete understanding of interactions between P. perfoliata and R. latipes under different abiotic conditions.

Using Monte Carlo Method for Predicting Rainfall -- Taking Xi'an Area, Shaanxi Province, China, as an Example

Rainfall forecasting plays a vital role in the national economy, social development and human life. Based on Monte Carlo method, this paper uses P- III distribution function to fitting precipitation data in the past 63 years so as to forecast precipitation. Using this model to forecast the rainfall for the past ten years (2003 ~~2013) in Xi'an city, Shaanxi province, China, based on the past 63 years data. The predicted results indicate that the prediction has a high accuracy in normal rainfall year, but in extremely in dry condition and high rainfall year, the relative error is huge. So that，the method is more suitable for the prediction of rainfall in the flat water.

On the natural history and functional morphology of the clam shrimp, Lynceus brachyurus Müller (Branchiopoda: Laevicaudata)

The small bivalved clam shrimp, Lynceus brachyurus Muller, 1776, is seasonally abundant in two long-duration vernal pools in central Ohio, USA. Previously unrecognized anatomical features include dorsal patches of spines or filaments on posterior trunk segments, diverse medial spines on the dorsal lobes of the leg exopods, two-segmented dorso-lateral appendages on the male eleventh segment, and brown coloration on portions of male legs. It can swim actively, but is basically benthic. Females are sometimes totally quiescent. Gut contents, observation, and experiments showed a diet of substrate scrapings, suspended detritus, and small zooplankton. Females ovulate following male stimulation and produce new egg batches without an intervening molt. Repeated matings are needed to produce the large egg masses often carried. Larvae were first collected in late February, and adults in late April. Lynceus was found in nine of the eleven years studied, being absent in the years that followed two years of high rainfall.

Radiation and energy balance dynamics over young chir pine (Pinus roxburghii) system in Doon of western Himalayas

The regional impacts of future climate changes are principally driven by changes in energy fluxes. In this study, measurements on micrometeorological and biophysical variables along with surface energy exchange were made over a coniferous subtropical chir pine (Pinus roxburghii) plantation ecosystem at Forest Research Institute, Doon valley, India. The energy balance components were analyzed for two years to understand the variability of surface energy fluxes, their drivers, and closure pattern. The period covered two growth cycles of pine in the years 2010 and 2011 without and with understory growth. Net short wave and long wave radiative fluxes substantially varied with cloud dynamics, season, rainfall induced surface wetness, and green growth. The study clearly brought out the intimate link of albedo dynamics in chir pine system with dynamics of leaf area index (LAI), soil moisture, and changes in understory background. Rainfall was found to have tight linear coupling with latent heat fluxes. Latent heat flux during monsoon period was found to be higher in higher rainfall year (2010) than in lower rainfall year (2011). Higher or lower pre-monsoon sensible heat fluxes were succeeded by noticeably higher or lower monsoon rainfall respectively. Proportion of latent heat flux to net radiation typically followed the growth curve of green vegetation fraction, but with time lag. The analysis of energy balance closure (EBC) showed that the residual energy varied largely within ±30% of net available energy and the non-closure periods were marked by higher rainspells or forced clearance of understory growths.

Wildlife Habitat Quality (Sward Structure and Ground Cover) Response of Mixed Native Warm-Season Grasses to Harvesting

Agricultural intensification in America has replaced native warm-season grasses (NWSG) with introduced forages causing wildlife habitat loss and population declines for the northern bobwhite (Colinus virginianus) and similar ground-nesting birds. Reintroducing NWSGs onto managed grasslands to reverse grassland bird population declines lacks information about appropriate multi-purpose management. Post-season nesting habitat quality of mixed NWSGs (indiangrass (IG, Sorghastrum nutans), big bluestem (BB, Andropogon gerardii) and little bluestem (LB, Schizachyrium scoparium)) responding to previous-year(s) harvest intervals (treatments, 30-, 40-, 60-, 90 or 120-d) and duration (years in production), were assessed on late-spring-early-summer re-growths. Yearly phased harvestings were initiated in May on sets of randomized plots, ≥90-cm apart, in five replications (blocks) to produce one-, two-, and three-year old stands by the third year. Sward heights and canopy closure were recorded a day before harvest, followed a week after by visual estimates of ground cover of plant species and litter. Harvesting increased post-season grass cover and reduced forbs following a high rainfall year. Harvested plot swards showed no treatment differences, but were shorter and intercepted more sunlight. Similarly, harvest duration increased grass cover with no year effect but reduced forbs following a high rainfall year. One- or two-year full-season harvesting of similar stands may not compromise subsequent bobwhite nesting-cover provided post-season harvesting starts after the breeding cycle is completed.

Contrasting above‐ and belowground sensitivity of three Great Plains grasslands to altered rainfall regimes

Intensification of the global hydrological cycle with atmospheric warming is expected to increase interannual variation in precipitation amount and the frequency of extreme precipitation events. Although studies in grasslands have shown sensitivity of aboveground net primary productivity (ANPP) to both precipitation amount and event size, we lack equivalent knowledge for responses of belowground net primary productivity (BNPP) and NPP. We conducted a 2-year experiment in three US Great Plains grasslands--the C4-dominated shortgrass prairie (SGP; low ANPP) and tallgrass prairie (TGP; high ANPP), and the C3-dominated northern mixed grass prairie (NMP; intermediate ANPP)--to test three predictions: (i) both ANPP and BNPP responses to increased precipitation amount would vary inversely with mean annual precipitation (MAP) and site productivity; (ii) increased numbers of extreme rainfall events during high-rainfall years would affect high and low MAP sites differently; and (iii) responses belowground would mirror those aboveground. We increased growing season precipitation by as much as 50% by augmenting natural rainfall via (i) many (11-13) small or (ii) fewer (3-5) large watering events, with the latter coinciding with naturally occurring large storms. Both ANPP and BNPP increased with water addition in the two C4 grasslands, with greater ANPP sensitivity in TGP, but greater BNPP and NPP sensitivity in SGP. ANPP and BNPP did not respond to any rainfall manipulations in the C3 -dominated NMP. Consistent with previous studies, fewer larger (extreme) rainfall events increased ANPP relative to many small events in SGP, but event size had no effect in TGP. Neither system responded consistently above- and belowground to event size; consequently, total NPP was insensitive to event size. The diversity of responses observed in these three grassland types underscores the challenge of predicting responses relevant to C cycling to forecast changes in precipitation regimes even within relatively homogeneous biomes such as grasslands.

Life-history traits predict perennial species response to fire in a desert ecosystem.

The Mojave Desert of North America has become fire-prone in recent decades due to invasive annual grasses that fuel wildfires following years of high rainfall. Perennial species are poorly adapted to fire in this system, and post-fire shifts in species composition have been substantial but variable across community types. To generalize across a range of conditions, we investigated whether simple life-history traits could predict how species responded to fire. Further, we classified species into plant functional types (PFTs) based on combinations of life-history traits and evaluated whether these groups exhibited a consistent fire-response. Six life-history traits varied significantly between burned and unburned areas in short (up to 4 years) or long-term (up to 52 years) post-fire datasets, including growth form, lifespan, seed size, seed dispersal, height, and leaf longevity. Forbs and grasses consistently increased in abundance after fire, while cacti were reduced and woody species exhibited a variable response. Woody species were classified into three PFTs based on combinations of life-history traits. Species in Group 1 increased in abundance after fire and were characterized by short lifespans, small, wind-dispersed seeds, low height, and deciduous leaves. Species in Group 2 were reduced by fire and distinguished from Group 1 by longer lifespans and evergreen leaves. Group 3 species, which also decreased after fire, were characterized by long lifespans, large non-wind dispersed seeds, and taller heights. Our results show that PFTs based on life-history traits can reliably predict the responses of most species to fire in the Mojave Desert. Dominant, long-lived species of this region possess a combination of traits limiting their ability to recover, presenting a clear example of how a novel disturbance regime may shift selective environmental pressures to favor alternative life-history strategies.

Seedbank dynamics after masting in mulga (Acacia aptaneura): Implications for post-fire regeneration

Members of the arid Australian mulga (Acacia aneura) complex are fire-sensitive shrubs that produce mast seed crops after exceptionally high rainfall years. Such years also drive widespread wildfires in inland Australia, as high rainfall causes grassy fuels to accumulate, thereby enabling fuel contiguity to occur. Despite seedling regeneration playing an important role in mulga post-fire recovery, a dearth of information exists on the dynamics of its seedbanks. Here we examine the temporal and spatial dynamics of mulga seedbanks after a region-wide masting event at Laycock's Sandplain, central Australia. Masting had a profound effect on seedbanks, producing massive but short-lived pulses of seed in upper soil layers. After seed fall, seedbanks declined rapidly, and within 18 months had been reduced by predator depredations to low pre-mast levels. Our results suggest that mulga masting should enhance resilience to burning by providing transient seed pulses during periods of high flammability (i.e. after heavy rainfalls). The results also suggest that burn intensity will influence post-fire regeneration, by interacting with seed germination biology and post-mast seedbank dynamics. In our discussion, we examine possible evolutionary drivers behind mulga seeding periodicity, and hypothesize that rain-driven masting in mulga is a fire-related form of environmentally predictive masting.

Timing of predispersal prospecting is influenced by environmental, social and state-dependent factors in meerkats

Extraterritorial prospecting forays are an important route to fitness in many species, allowing the assessment of dispersal opportunities and often extragroup mating prior to dispersal. However, few studies have examined the factors affecting individual variation in prospecting effort and the extent to which individuals time their forays so as to maximize the benefits and mitigate the costs of prospecting. We used 11 years of prospecting data from a wild population of cooperatively breeding meerkats, Suricata suricatta, to investigate how subordinate males modulate their prospecting effort according to their social and physical environment and internal state. Prospecting effort showed strong seasonal variation, in which peak prospecting broadly coincided with the breeding season. When we controlled for this seasonal variation, we found that males were more likely to prospect when there were larger numbers of females evicted from foreign groups (with whom prospecting males found new groups) and on days when they encountered another social group (to which they could then prospect at minimal cost). Males were also more likely to prospect when older, in stronger body condition and in years of higher rainfall (when greater food availability may reduce prospecting costs and improve the chance of encountering fertile females). Finally, although travelling in larger coalitions can mitigate the costs of prospecting, males with more potential coalition partners were less likely to prospect. Together, our results indicate that individual investment in predispersal prospecting forays is influenced by social, environmental and state-dependent factors that may shape the benefits and mitigate the costs of extraterritorial prospecting. Our findings suggest that males rely more on extragroup than within-group social cues when timing their forays, and provide new insights into the likely drivers of spatiotemporal patterns of dispersal and extragroup mating in social species.