Microsite Selection Research Articles

Automated precise seeding with drones and artificial intelligence: a workflow

Aerial seeding with drones has great potential in forest restoration but faces enormous challenges to be efficient and scalable. Current protocols use blanket seeding throughout the area to be restored, meaning a high demand for seed since many seeds arrive in sites unsuitable for establishment. High precision seeding directed to safe microsites at submeter scale could reduce seed use per hectare, reducing economic and ecological costs, while increasing establishment success. Here, we propose an alternative, precision approach to make drone seeding more successful and efficient. This requires (1) submeter‐scale selection of target microsites for seeding founded in ecological knowledge; (2) high‐resolution remote sensing imagery to train artificial intelligence (AI) systems in target microsite recognition; and (3) process automation by transferring target microsite coordinates from the AI system to the drone. This will reduce seed inputs per unit area, seedling establishment failure risks, and drone operation costs.

Deer browse deterrents and microsite selection influence Callitropsis nootkatensis and Thuja plicata planting success in Southeast Alaska

Deer browse deterrents and microsite selection influence Callitropsis nootkatensis and Thuja plicata planting success in Southeast Alaska

Nonparametric copula modeling of wind speed-wind shear for the assessment of height-dependent wind energy in China

The joint probability density function can quantitatively describe the statistical characteristics and correlation features between wind speed and shear; this forms the theoretical basis for assessing height-dependent wind energy. Here, a nonparametric copula-based joint probability model of wind speed-wind shear is developed to assess height-dependent wind energy in China. Utilizing the transformation method and optimal bandwidth algorithms, a nonparametric copula model for wind speed/wind shear correlation analysis is proposed. Joint probability density models of wind speed and wind shear are then constructed. Various copula and marginal density models (including single parametric, mixture parametric, and kernel density estimation models) are evaluated at the regional scale. The nonparametric copula model exhibits remarkable superiority and is therefore deemed to be more suitable for wind speed/wind shear correlation analysis and joint probability modeling. When assessing height-dependent wind energy, the average distributions of wind turbine power output and capacity factor are obtained across mainland China. Additionally, this model could accurately analyze variations in wind power density with respect to hub height. These results can effectively facilitate accurate micro-site selection, thereby economically benefiting wind farms.

Optimising conservation translocations of threatened

Context Conservation translocations are increasingly being used in the management of rare plants, yet have low success in maintaining populations through recruitment. Aims We investigated whether the survival of translocated plants, recruitment and, therefore, cost effectiveness, can be improved by selecting optimal microsites for both adults and seedlings. Methods Caladenia colorata plants propagated symbiotically with Serendipita australiana (n = 735) were introduced to four sites where the pollinator was present and vegetation matched wild populations. Plant demography was monitored over 6 years. The relationship between microsite variables and measures of orchid survival, re-emergence, flowering and recruitment were analysed with generalised linear mixed-effects models. We then estimated potential improvement in emergence and recruitment, if microsite selection was optimised. Key results A total of 77% of plants survived translocation, and populations grew by 84% through recruitment (n = 615). Survival was positively associated with cover of leaf litter, graminoids and cryptogams. Recruitment was positively correlated with soil moisture. The majority of recruitment was within 5 cm of adult C. colorata plants. The potential improvement by selecting favourable microsites increased adult survival by up to 8% and recruitment by 10–40%. Conclusions Incorporating both the germination niche and adult plant niche within plant translocations more broadly could significantly improve long-term population persistence and the utilisation of conservation funding. Implications Our results are directly applicable to 58 endangered Caladenia species in the subgenus Calonema, owing to their shared mycorrhizal association with S. australiana. Furthermore, our results are applicable to all plant translocations as understanding germination niche and microhabitat requirements is likely to improve success overall.

Effects of forest preservation, livestock exclusion, and use of shrubs as potential nurses on planting success of an endangered tree

Domestic livestock are widespread in seasonally dry forests, likely causing forest degradation and limiting tree seedling establishment. Shrubs can play an important role in facilitating tree regeneration, by protecting trees from livestock damage and ameliorating unfavorable abiotic conditions. We aimed at disentangling the relative contribution of grazing exclusion, long‐term forest conservation, and the potential facilitation effect of shrubs on the performance of saplings of the native tree Kageneckia lanceolata. We planted 400 saplings in grazed and ungrazed areas situated both in a preserved and a degraded forest. In each situation, we established planting plots in three accompanying vegetation treatments: herbs, a nonleguminous spiny shrub and a leguminous spiny shrub. Survival of 3‐year‐old saplings was 10‐fold higher in the preserved than in the degraded forest and 2‐fold higher in the ungrazed than in the grazed site. Differences in survival among accompanying vegetation treatments were much smaller than between grazing treatments. Survival significantly increased with increasing protection by shrubs only in the degraded site. Sapling growth patterns were fairly similar to survival patterns, with no growth in the degraded forest, except for limited growth under both shrubs in the ungrazed site. We conclude that, in selecting plantation sites for the study species, forest condition and grazing exclusion should be prioritized over microsite selection based on neighboring vegetation.

Influence of wind energy utilization potential in urban suburbs: a case study of Hohhot

Given the increasing trend of using wind energy in cities, the utilization of distributed wind energy in cities has been widely concerned by researchers. The related research on the micro-site selection of wind turbines, a sub-project of the Task27 project of the International energy agency, was continued in this paper. The wind speed data of an observation station near Hohhot, Inner Mongolia, with a range of 10–19 m were collected. The evaluation included wind direction, Weibull parameter characteristics, and turbulence intensity. The potential energy output in 10 different heights was estimated using commercial horizontal and vertical axis wind turbines of the same power. Results showed that the following: the three-parameter Weibull distribution model can well describe the statistical properties of the wind speed in this site. The wind speed distribution model constructed from extrapolation parameters reflects the wind speed statistical properties out of detection positions to a certain extent. The wind energy density of the vertical axis wind turbine is slightly lower than that of the horizontal axis wind turbine. Furthermore, more power can be generated from March to May.

Seed predation and dispersal by small mammals in a landscape of fear: effects of personality, predation risk and land‐use change

Scatter‐hoarding small mammals act as both seed predators and seed dispersers in forest ecosystems. Their choices regarding consuming or caching seeds must balance the risk of predation with the energy rewards gained from immediate or delayed consumption of seeds. Several factors influence their interaction with seeds, including the individual's personality. Little is known about how personality affects foraging decisions in response to predation risk. This missing information is critical because if foraging decisions differ among individuals in response to perceived risk, then varying combinations of personality types in a population (and varying risks of predation across forest types) may have diverse effects on forest regeneration. Further, land‐use change may influence the interplay of personality, risk perception and foraging decisions by altering the distribution of personality types in the landscape and the risk perceived by individuals. To contribute to filling these knowledge gaps, we designed a large‐scale field experiment to evaluate how personality, perceived predation risk and land‐use change affect the interaction of deer mice Peromyscus maniculatus and seeds. Using infrared cameras, we recorded the choices of individuals of known personality at paired experimental sites with high versus low perceived predation risk (n = 2389 observations from 74 individuals). We found that personality influenced multiple foraging decisions, and perceived risk affected how individuals with different personalities responded to those decisions. Specifically, exploration/activity influenced seed choice, boldness affected the number of seeds selected and docility influenced both foraging site selection and whether mice immediately consumed or removed seeds. Since personality only affected foraging microsite selection in unmanaged forests, our results show that land‐use change decreased the importance of personality in affecting risk perception. We demonstrate the importance of considering personality on foraging decisions under varying levels of risk, and more generally, underscore the importance of considering individual variation in affecting ecological processes.

Vegetation Structural Attributes Providing Thermal Refugia for Northern Bobwhites

ABSTRACTThe northern bobwhite (Colinus virginianus; bobwhite) exists at the edge of its thermal tolerance in southern Texas, USA, a region characterized by extreme heat and periodic drought. Extreme heat and drought events are predicted to increase in frequency and intensity in semi‐arid regions, leading biologists to emphasize management of thermal cover. The degree to which temperatures within patches of woody vegetation vary and the specific vegetation structural characteristics that create cooler microclimates within these patches are unknown. We evaluated temperature variation between selected and available sites, vegetation characteristics facilitating cooler microsites, and whether these characteristics in addition to temperature were important predictors of microsite selection within woody patches. We radio‐tracked 83 bobwhites 2–3 times/week during April–August 2017–2018. We recorded operative and ground surface temperatures and measured woody and herbaceous vegetation height, canopy density, and overlapping woody and herbaceous cover at used and paired random locations. Within the same woody patch, 80% of used locations contained operative temperatures lower than or equal to random locations. There was a weak relationship between the vegetation variables we measured and temperature at paired locations, indicating that none of the vegetation variables alone can effectively reduce temperatures. Temperatures within woody patches are likely strongly tied to diurnal variation in solar angle and ability to create shade. Cooler temperatures, dense canopies, and overlapping woody vegetation had the greatest effects on relative probability of microsite use during the middle of the day, whereas warmer temperatures and taller woody vegetation had the greatest relative effects during the morning and evening. Our results suggest that temperature was influential across diurnal periods but foraging and predation avoidance may have also been important. Maintenance and preservation of dense woody vegetation and diverse shrub understories must be prioritized in habitat management for bobwhites in semi‐arid regions. © 2021 The Wildlife Society.

Awn Morphology Influences Dispersal, Microsite Selection and Burial of Australian Native Grass Diaspores

© Copyright © 2020 Cavanagh, Morgan and Godfree. Seed dispersal is a vital part of a plant’s life cycle that enables progeny to reach new sites suitable for burial and establishment. Awns are characteristic of many grass species and enable diaspores to self-disperse. Little is known, however, about the role of different awn morphologies in dispersal or burial. The objective of this study was to investigate the influence of awn morphology on diaspore surface dispersal and burial among representative Australian Poaceae. Surface dispersal, burial and microsite selectivity of diaspores were compared across 30 grass species and ten awn morphological types using laboratory and natural simulation experiments. The presence of an awn significantly facilitated surface dispersal and burial of diaspores, with awn length and hygroscopic activity being positively related to both surface dispersal and burial depth. Geniculate (once-bent) and bigeniculate (twice-bent) awns were the most efficient at surface dispersal. Burial efficiency, however, was influenced by microsite conditions; a surface obstruction increased burial for almost all awn types, while falcate (curved)-awned species were effective at burying without such objects. This study indicates that awn morphologies likely play different functional roles in the success of Australian grass progeny.

Wind Energy Resource Assessment Based on WRF Model and Key Model for Micro-site Selection of Wind Farms

Wind Energy Resource Assessment Based on WRF Model and Key Model for Micro-site Selection of Wind Farms

Improving restoration success through microsite selection: an example with planting sagebrush seedlings after wildfire

Post‐fire restoration of foundation plant species, particularly non‐sprouting shrubs, is critically needed in arid and semi‐arid rangeland, but is hampered by low success. Expensive and labor‐intensive methods, including planting seedlings, can improve restoration success. Prioritizing where these more intensive methods are applied may improve restoration efficiency. Shrubs in arid and semi‐arid environments can create resource islands under their canopies that may remain after fire. Seedlings planted post‐fire in former canopy and between canopies (interspace) may have different survival and growth. We compared planting Wyoming big sagebrush (Artemisia tridentata Nutt. ssp. wyomingensis Beetle & Young) seedlings post‐fire in former sagebrush canopy and interspace microsites at five locations. Four growing seasons after planting, seedling survival was 46 and 7% in canopy and interspace microsites, respectively. Sagebrush cover was 5.8 times greater in canopy compared to interspace microsites. Sagebrush survival and cover were likely greater because of less competition from herbaceous vegetation as well as benefiting from resource island effects in canopy microsites. Initially, post‐fire abundance of exotic annual grasses was less in canopy microsites, but by the third year post‐fire it was substantially greater in canopy microsites, indicating that resource availability to seedlings was greater, at least initially, in canopy microsites. These results suggest microsites with greater likelihood of success should be identified and then utilized to improve restoration success and efficiency. This is important as the need for restoration greatly exceeds resources available for restoration.

Heat dissipation behaviour of birds in seasonally hot arid‐zones: are there global patterns?

Quantifying organismal sensitivity to heat stress provides one means for predicting vulnerability to climate change. Birds are ideal for investigating this approach, as they display quantifiable fitness consequences associated with behavioural and physiological responses to heat stress. We used a recently developed method that examines correlations between readily‐observable behaviours and air temperature (Tair) to investigate interspecific variation in avian responses to heat stress in seasonally hot, arid regions on three continents: the southwestern United States, the Kalahari Desert of southern Africa and the Gascoyne region of western Australia. We found substantial interspecific variation in heat dissipation behaviours (wing‐drooping, panting, activity‐reduction, shade‐seeking) across all three regions. However, pooling the data revealed that little of this interspecific variation was systematically explained by organismal traits (foraging guild, diet, drinking dependency, body mass or activity levels) at the scale we tested. After accounting for phylogeny, we found that larger birds engaged in wing‐drooping behaviour at lower Tair and had lower activity levels at high Tair compared to smaller birds, indicating an effect of body mass on heat dissipation behaviour (HDB). In the Kalahari, reliance on drinking was correlated with significantly lower Tair at which panting commenced, suggesting a key role of water acquisition in HDB in that region. Birds also tended to retreat to shade at relatively lower Tair when more active, suggesting a behavioural trade‐off between activity, heat load and microsite selection. Our results imply that the causes underlying interspecific variation in heat dissipation behaviours are complex. While the variation we observed was not systematically explained by the broad scale organismal traits we considered, we predict that the indices themselves will still reflect vulnerability to potential fitness costs of high air temperatures. Further research is needed on a species‐specific basis to establish the functional significance of these indices.

Regional Climate, Edaphic Conditions and Establishment Substrates Interact to Influence Initial Growth of Black Spruce and Jack Pine Planted in the Boreal Forest

In eastern Canada, spruces (Picea spp.) and pines (Pinus spp.) are among the main commercial species being logged for their lumber or wood fiber. Annually, about 175 million seedlings are planted in areas totaling ~100,000 ha. Appropriate microsite selection is essential during reforestation operations, given that it can improve the chances of survival and initial growth of the seedlings. In fir (Abies spp.) and spruce forests of eastern Canada, the optimal characteristics of establishment microsites have yet to be identified; these would be determined by different physical and climatic variables operating at several scales. Our study determined the influence of climatic (regional-scale), edaphic (stand-scale), local (microsite-scale) and planting conditions on the establishment substrate and initial growth of black spruce (Picea mariana Britton, Sterns and Poggenb.) and jack pine (Pinus banksiana Lamb.). Substrate characterization and growth monitoring (three growing seasons) for the two species were conducted on 29 planted cutblocks that were distributed over an east–west climatic gradient (precipitation and temperature) in the balsam fir and black spruce–feather moss forests of Quebec (Canada). Linear mixed models and multivariate analyses (PCAs) determined the effects of climatic, edaphic and micro-environmental variables and their interactions on the establishment substrate and seedling initial growth. The predictive models explained, respectively, 61% and 75% of the growth variability of black spruce and jack pine. Successful establishment of black spruce and jack pine depended upon regional conditions of precipitations and temperature, as well as on their interactions with stand-scale edaphic variables (surface deposit, drainage and slope) and local variables (micro-environmental) at the microsite-scale (establishment substrate types and substrate temperature). Mineral, organo-mineral and organic establishment substrates exerted mixed effects on seedling growth according to regional precipitation and temperature conditions, as well as their interactions with edaphic and local variables at the stand and microsite-scales, respectively.

Den site selection by golden jackal (Canis aureus) in a semi arid forest ecosystem in western india

The availability of dens in habitat is essential for successful recruitment and it is confining factor for the distribution and abundance of den dependent species. Present study was conducted in Sariska Tiger Reserve, Rajasthan, India. To determine the most influential variable for selectivity of den sites by golden jackal (Canis aureus), data on habitat characteristics were studied at two scales. The physical structure and protective capabilities of dens were studied at small scale (microsite selection) by use- availability design along with discrete choice models. The selection of den in relation to environmental factors was studied at larger scale (macrosite selection) using binary logistic regression in generalized linear model. Thirty six jackal dens were observed in the study area (0.23 den/km2). The hypothesis received support as a factor for den site selection was ‘ease of excavation’ at micro scale (314 m2) and ‘cover and resource’ at macro scale (3.14 km2). Areas with high cover were observed having less number of dens (r = -0.76, p =0.02) at significant level. Variables favoring natal den selection was no different than overall selected den sites. Jackal showed no significant avoidance for large carnivore presence where, rodent abundance and visibility were the important predictors for den- sites selection in the study area.

Landscape influence on the local distribution of western pond turtles

AbstractSpatial and temporal scales are important for understanding habitat associations because organisms have neither unbounded mobility nor perfect knowledge of their environment, but still must make decisions on where to seek food, shelter, and mates. Semi‐aquatic turtles exemplify the need to evaluate potential habitat characteristics at a range of scales, because their ectothermy makes these animals particularly sensitive to local environmental conditions, yet their limited mobility spatially constrains selection of microsites. Microsite choice may also be sensitive to larger geographic context. We explored site occupancy and abundance of western pond turtles (Actinemys [Emys] marmorata) as a function of environmental variables over a range of spatial scales up to that of the entire watershed. We modeled occupancy at ponds and abundance at river sites using data from surveys conducted at 50 ponds and 58 river locations throughout the South Umpqua, Umpqua, and North Umpqua watersheds in western Oregon, USA in 1999–2000. The South Umpqua supported the greatest abundance of western pond turtles in rivers and the highest rates of occupancy in ponds. No turtles were detected in rivers of the North Umpqua, and only low numbers were detected in ponds in that watershed. Increasing amount of potential relative solar radiation was associated with increased probability of pond occupancy, particularly in the North Umpqua watershed. Pond turtle abundance in rivers increased with increasing distance to nearest pond, decreasing area of nearby ponds, and increasing area of nearby wetland habitat of all types, particularly in the Klamath Mountain and Coast Range physiographic provinces, which dominate the South Umpqua and Umpqua watersheds, respectively. Western pond‐turtle occupancy and abundance varied with both broad‐scale and fine‐scale habitat features, not solely to the fine‐scale features that are most often measured.

Selection of rest structures and microsites by fishers in Oregon

ABSTRACTMost previous studies of resting habitat for fishers (Pekania pennanti) in the Pacific coastal region of the western United States and Canada were focused on habitat conditions within rest sites (typically ≤0.5 ha), which include the rest structure (e.g., live tree, snag, log) at its center. Studies of selection for rest structures were sparse and compared characteristics of rest structures to those occurring within rest sites; none investigated selection by sampling resource availability throughout the study area. In addition, limited data were available on the use of rest microsites (e.g., mistletoe brooms, platform branches, cavities) by fishers, and no studies have quantified their availability. To better inform forest management activities designed to improve resting habitat for fishers, we documented use of rest structures and microsites throughout the year by 12 female and 7 male fishers on the west slope of the Cascade Range in southern Oregon, USA from 1995 to 2001, systematically sampled the availability of rest structures and microsites, and used logistic regression modeling to investigate selection of rest structures. Fishers primarily used live trees (65%), snags (14%), and logs (16%) for resting; in all 3 resulting models, the characteristic that best distinguished used from available rest structures was the presence of a suitable rest microsite: mistletoe broom or cavity in live trees, cavity in snags, and hollow end in logs. Only the snag and log models included covariates associated with tree size, likely reflecting the need for enclosed rest microsites (cavities, hollow ends) to be large enough to contain an adult fisher. We then used our availability data to model the ecological characteristics associated with mistletoe brooms in live trees, cavities in snags, and hollow ends in logs. Whether a tree was a hemlock (Tsuga spp.) had the greatest effect on the presence of suitable mistletoe broom microsites, but the most important characteristics of snags with cavities and logs with hollow ends were being in moderate stages of decay and relatively large in diameter at breast height (snags) or diameter 3 m from the large end (logs). Forest structures containing suitable rest microsites for fishers were uncommon in our study and may represent a limited resource. Accordingly, we recommend that management of resting habitat for fishers be focused on retaining relatively large structures that already contain suitable rest microsites, rather than simply retaining the largest available structures. Published 2018. This article is a U.S. Government work and is in the public domain in the USA.

Methods to Improve Survival and Growth of Planted Alternative Species Seedlings in Black Ash Ecosystems Threatened by Emerald Ash Borer

Emerald ash borer (EAB) continues to spread across North America, infesting native ash trees and changing the forested landscape. Black ash wetland forests are severely affected by EAB. As black ash wetland forests provide integral ecosystem services, alternative approaches to maintain forest cover on the landscape are needed. We implemented simulated EAB infestations in depressional black ash wetlands in the Ottawa National Forest in Michigan to mimic the short-term and long-term effects of EAB. These wetlands were planted with 10 alternative tree species in 2013. Based on initial results in the Michigan sites, a riparian corridor in the Superior Municipal Forest in Wisconsin was planted with three alternative tree species in 2015. Results across both locations indicate that silver maple (Acer saccharinum L.), red maple (Acer rubrum L.), American elm (Ulmus americana L.), and northern white cedar (Thuja occidentalis L.) are viable alternative species to plant in black ash-dominated wetlands. Additionally, selectively planting on natural or created hummocks resulted in two times greater survival than in adjacent lowland sites, and this suggests that planting should be implemented with microsite selection or creation as a primary control. Regional landowners and forest managers can use these results to help mitigate the canopy and structure losses from EAB and maintain forest cover and hydrologic function in black ash-dominated wetlands after infestation.

Microsite selection and survival of greater sage-grouse nests in south-central Wyoming

Greater sage-grouse (Centrocercus urophasianus; hereafter, sage-grouse) populations have declined across North America because of degradation of sagebrush (Artemisia spp.) ecosystems; thus, management for sage-grouse habitat is a high priority. Expansion of some energy development has put additional pressures on sage-grouse populations and their habitats. However, little is known about the effects wind energy development may have on sage-grouse populations. Population dynamics of sage-grouse are partially related to nest success, which may be influenced by the quality of nesting habitat. Consequently, knowledge of vegetation and structural characteristics associated with selection and survival of sage-grouse nests would help inform management decisions to improve nest success. As part of a study quantifying greater sage-grouse demographics prior to construction of a wind energy facility, we monitored female sage-grouse equipped with 30-g solar Argos global positioning system platform transmitter terminals during the breeding season in Carbon County, Wyoming to assess selection and survival of nests at nest area (30-m radius), nest patch (5-m radius), and nest bowl scales. Sage-grouse selected nest sites with increased visual obstruction from 22.9–45.7 cm in height at all scales, less forb cover at the nest area, and more sagebrush cover at the nest patch. Survival of nests to 27 days (i.e., incubation period) was 43.3% (95% CI: 31.8–59.1%) in 2011 (n = 49), 33.2% (95% CI: 21.5–51.3%) in 2012 (n = 40), and 25.1% (95% CI: 15.0–42.0%) in 2013 (n = 39). Grass height had a positive association with survival of nests at the nest area and nest patch, canopy cover of bunchgrasses and sagebrush had an interactive effect on survival of nests at the nest patch, and visual obstruction from 0–22.9 cm in height had a positive relationship with survival of nests at the nest bowl. The standardized precipitation-evapotranspiration index (SPEI), an index of drought, from the previous growing season was also negatively correlated with survival of nests. Our results suggest management for nesting sage-grouse should focus on a heterogeneous compilation of tall bunchgrasses >15 cm and patches of sagebrush cover >30%. Management for grasses >15 cm tall should be especially diligent during drought years, given SPEI was associated with nest survival the following year. Although there could be other factors important to selection or survival of nests that we did not evaluate, our results suggest scale-dependent management strategies at the microsite level may not be necessary. We encourage researchers and managers to use our baseline results in a before–after control-impact design with future, post-construction data to determine the potential effects of wind energy development on selection and survival of sage-grouse nests. © 2016 The Wildlife Society.

DISTRIBUCIÓN DE LOS CULTIVOS PIAROA Y SU RELACIÓN CON LAS PROPIEDADES Y CARACTERÍSTICAS EDÁFICAS, EN LOS CONUCOS DE LA ORINOQUIA VENEZOLANA

El sistema de agricultura migratoria, determinante en la soberanía alimentaria de los indígenas Piaroa en la orinoquia venezolana, es una actividad antropocéntrica que ha permitido conservar la dinámica del bosque húmedo tropical. En la actualidad, los cambios ocasionados por los procesos de globalización amenazan la sostenibilidad del sistema. Por tal motivo, el estudio a detalle de su funcionamiento es preponderante para la toma de decisiones referentes al manejo del bosque. Esta investigación planteó determinar la relación existente de las especies cultivadas con algunas propiedades y características físicas y químicas del suelo, en la etapa de siembra. Para ello, 40 unidades de muestreo (suelo y vegetación) se ubicaron en diferentes conucos Piaroa, en dos periodos distintos después de la quema. Con base en los datos de campo, se desarrolló un modelo para explicar la distribución espacial de cada una de las especies cultivadas a partir de las características edáficas. El modelo aplicado presentó distintas respuestas en función de las especies cultivadas por los indígenas. Sin embargo, explica la selección de micrositios para la siembra a través de las propiedades físicas del suelo, la distribución de la hojarasca y la distribución de la biomasa después de la tumba y quema en el conuco.

Seed moisture content affects afterripening and smoke responsiveness in three sympatric Australian native species from fire‐prone environments

AbstractGermination of freshly collected seeds of three sympatric herbaceous species native to fire‐prone environments in south‐western Australia was significantly improved through the application of novel combinations of dry heat, gibberellic acid, smoke water and dry afterripening. For fresh seeds, combinations of dry heat, gibberellic acid and/or smoke water resulted in >80% germination in Austrostipa elegantissima (Poaceae) and Stylidium affine (Stylidaceae) seeds and >60% germination in Conostylis candicans (Haemodoraceae) seeds, compared with <10% germination of control seeds. For fresh seeds, two broad germination patterns were observed in response to smoke water: nil – low germination for both control and smoke water‐treated seeds (A. elegantissima and S. affine); and a significant smoke response (35%) compared with control seeds (1%) (C. candicans). During afterripening, high germination for A. elegantissima seeds was achieved following 3 months storage of seeds at equilibrium relative humidities of 23–75%, but seeds stored at 5–13% equilibrium relative humidities took 6–36 months to achieve similar levels of germination. Germination of C. candicans seeds also increased after 3 months storage, to >60% at each equilibrium relative humidity and further increases over time were slight. For S. affine seeds >60% germination was achieved only after 36 months storage at 50% equilibrium relative humidity. Seeds from all three species were smoke‐responsive at some point, but the interaction/effects of afterripening on the smoke response varied significantly between species. This study highlights an apparent effect of seed dormancy status on response to smoke and a surprisingly high level of ecological variation in pre‐germination requirements (cues) for these co‐occurring species that may relate to variation(s) in microsite selection forces operating on the soil seed bank of the different species.