Sand Substrate Research Articles

KARAKTERISTIK HABITAT TEMPAT BERTELUR PENYU SISIK (Eretmochelys imbricata ) DI TAMAN WISATA ALAM TANJUNG KELUANG KECAMATAN KUMAI KALIMANTAN TENGAH

This research aimed to discover the characteristics of hawksbill turtle egg-laying place (Eretmochelys imbricata) in the Tanjung Keluang Nature Park of Kumai District Central Kalimantan. The data which is collected to describe the characteristics of the habitat covers the length of the beach, its width, its slope, the distance of the nest with the vegetation, the air humidity, the air temperature, the nest temperature, the moisture content of sand substrate, the texture of sand substrate, the water salinity, and other factors that threaten the hawksbill turtle egg-laying place habitat. From the location of the study, it was found that the length of the beach that becomes the egg-laying place is 5000 meters and 1200 meters that do not become the egg-laying place, the beach width is about 3 – 12 meters at the highest tide and 9 – 20 meters at the lowest tide, the slope of the beach where the nest is found ranges from 10 to 15% and 8 – 11% where the nest cannot be found, the nest distance with the vegetation is about 0 – 2 meters, the air humidity is around 94,7% - 68,8%, the air temperature is about 28,830C - 330C, the nest temperature is about 28,620C, the sand substrate texture is medium with 0,21 – 0,50 µm, and the sea water salinity is 27,5%. At the location of the study there was found that every hawksbill turtle nest located in a shade of sea pandan trees (Pandanus tectorius). Hawksbill turtles are threatened by predators such as monitor lizards (Varanus salvator), ghost crabs (Ocypoda sp), fishing activities, waste bins, and natural factors such as coastal abrasion and the presence of weeds growing on the beach surface. Keyword: Habitat Characteristics, Hawksbill turtle, Tanjung Keluang Natural Park

The influence of willow plantations and soil composition on the process of natural vegetation settlement at oil drilling sites in Western Siberia

Test cultures of various willow species were created in 1997 on a technogenic sandy site of one of oil deposits (62°46’18.36" N, 72°09’48.69" E). Sixty-five isolated plots, including various soil substrates (sand, peat, drilling wastes), were placed in the testing area of 684 m2. Optimum combinations of substrate components were identified, and the tolerance of willow species to drilling wastes was revealed by the results of investigating 1-5-year cultures [1]. In 2016 we investigated the natural settlement of aborigine plants in this test plot. The willow cultures mortality was high according to short offspring vegetative lifetimes and the limitation of feed areas. However, willow cultures and soil reclamation stimulated a settlement of natural plant seedlings. The comparison of phytocenoses, which were formed in various experimental and "background" conditions, has allowed making some conclusions. 44 plant species are growing now in the experimental area. The least number of species is characteristic for pure sand and pure peat substrates, the greatest − for complex substrates with sand, peat and drilling wastes. Thus, the experimental willow cultures and partial soil reclamation accelerated the formation process of forest ecosystems that created a "plant oasis" on a deserted landscape of technogenic sand.

Physicochemical aspects of recycling tree leaf litter in the south of Western Siberia by the Eisenia fetida (Savigny) vermiculture

The utility of the compost worm Eisenia fetida (Savigny) for recycling mixed leaf litter of the tree species characteristic of the forests in the south of Western Siberia and used in the landscaping in the city of Tomsk has been demonstrated. The tree species that are the major contributors to the leaf litter in the examined area include the genera Populus, Salix, and Betula. Two-fraction substrates for leaf litter vermicomposting and conventional composting (decomposition with and without earthworms) were prepared of the harvested and dried leaf litter. The feeding fraction consisted of leaf litter moistened with distilled water and the absorbing fraction, of alluvial river sand. The physicochemical properties of the studied leaf litter were weakly acidic pH of aqueous extracts, a very low content of nitrate nitrogen, and a relatively low K+ concentration. The prevalent cation in the assayed leaf litter was Ca2+. The leaf litter was partially decomposed on the surface of sand substrates during 35-day incubation under humid conditions; accumulation of inorganic ions in the sand was one of the signs indicating this decomposition. Ca2+ was also prevalent among these ions.

Propagation of Brazil nut (Humb. y Bonpl) seedlings using seeds in mini-greenhouses

The species Bertholletia excelsa H.B.K., the Brazil nut, is an Amazonian species belonging to the family Lecythidaceae. It has great economic value. One of the principle means of B. excelsa propagation is via sexual reproduction (seeds), but the presence of dormancy makes it difficult to produce seedlings, mainly due to the long germination period, and uncertainties regarding timing. The purpose of the current study was to describe a technology that allows the development, in mini-greenhouses, of all processes involved in Brazil nut seedling propagation. The study evaluated response of B. excelsa seedlings to different substrates in mini- greenhouses at the scarification, germination and growth stages. Germination counts were first was performed five days after sowing, and ended at 40 days, when no further germination was observed. Subsequently, germination percentages of normal and abnormal seedlings, dormant and dead seeds were calculated. Sawdust and forest soil substrates provided a shorter husk removal time, while forest soil substrate had the highest percentage of healthy seeds. Germination rates for B. excelsa seed in mini-greenhouses were not affected by substrate type. The substrates sand and sand+sawdust showed highest B. excelsa seedling development.

Регенераційна здатність зелених живців видів роду Catalpa Scop. у Правобережному Лісостепу України

Вивчено укорінення зеленими живцями представників роду Catalpa Scop. в умовах Правобережного Лісостепу України. Проведено дослідження з визначення регенераційної здатності зелених живців окремих видів роду Catalpa: C. bignonioides Walt., C. speciosa Ward., C. ovata, C. hybrida Spaeth. та C. fargesii. Визначено їхні оптимальні розміри, терміни заготівлі та способи укорінення в умовах досліджень. Заготівлю живців проводили у три терміни: в період інтенсивного (перша-друга декада червня), менш інтенсивного (перша декада липня) та повільного (перша декада серпня) росту пагонів. Живці з 2–6 бруньками завдовжки до 20 см нарізали з вегетуючих однорічних пагонів. Встановлено, що оптимальним терміном заготівлі живців є період інтенсивного росту пагонів – від першої до третьої декади червня, оптимальним терміном проведення зеленого живцювання – від третьої декади червня до першої декади липня. Для стимулювання ризогенезу використовували розчин ІМК різної концентрації. Робочий розчин готували в чотирьох варіантах: І – 20 мг ІМК на 1 л дистильованої води, ІІ – 40 мг/л, ІІІ – 60 мг/л, IV – 80 мг/л. Експозиція оброблення живців становила 12 годин. Доведено, що стимулятори коренеутворення значно підвищують частку отриманого укоріненого садивного матеріалу в досліджуваних видів. Найкращі показники укорінення зелених живців отримано за застосування стимулювальних розчинів ІМК та гетероауксину в концентрації 60 мг/л.

Environmental enrichment influences spatial learning ability in captive-reared intertidal gobies (Bathygobius cocosensis).

Behavioural plasticity is an advantageous trait for animals living in dynamic environments, and can be induced through learning. While some behavioural traits are innate, others are framed by experience and learning during an individual's lifetime. Many studies have investigated cognitive abilities in fish species from contrasting environments, but the relative contribution of natural selection versus behavioural plasticity in cognitive variability remains equivocal. Furthermore, rearing conditions in laboratories are often mundane, failing to encourage natural behaviour in the species used in these studies. Here, we captured juvenile gobies (Bathygobius cocosensis) from intertidal rockpools, and raised them in captivity under varied environmental enrichment treatments that mimic variation observed in coastal habitats. When tested in a simple spatial learning task, individuals from complex rearing treatments (rock or oyster substrate) reached learning criteria faster than those reared in less complex (seagrass) and homogenous environments (sand substrate). Interestingly, gobies reared in complex environments demonstrated longer latencies to start the task than gobies in homogeneous treatments. Our results indicate that cognitive ability is strongly shaped by individual experience during ontogeny, and exposure to reduced environmental complexity in early life leads to reduced cognitive abilities in intertidal gobies.

Evaluation of chronic toxicity of sodium chloride or potassium chloride to a unionid mussel (Lampsilis siliquoidea) in water exposures using standard and refined toxicity testing methods.

Freshwater mussels are generally underrepresented in toxicity databases used to derive water quality criteria, especially for long-term exposures. Multiple tests were conducted to determine the chronic toxicity of sodium chloride (NaCl) or potassium chloride (KCl) to a unionid mussel (fatmucket, Lampsilis siliquoidea). Initially, a 4-wk NaCl test and a 4-wk KCl test were conducted starting with 2-mo-old mussels in water exposures with and without a thin layer of sand substrate. A feeding study was conducted later to refine test conditions for longer-term 12-wk exposures, and 3 chronic NaCl tests were then conducted following the refined method to assess the influence of test duration (4-12 wk) and age of organisms (starting age ∼1 wk to 2 mo) on mussel sensitivity. Biomass (total dry wt of surviving mussels in a replicate) was generally a more sensitive endpoint compared to survival and growth (length and dry wt). In the 4-wk NaCl or KCl test started with 2-mo-old juveniles, a 20% effect concentration (EC20) based on biomass (264 mg Cl/L from the NaCl test or 8.7 mg K/L from the KCl test) in the exposure with sand was 2-fold lower than the EC20 in the exposure without sand. The longer-term 12-wk NaCl tests started with the 1-wk-old and 2-mo-old juveniles were successfully completed under refined test conditions based on the feeding study, and younger juveniles were more sensitive to NaCl than older juveniles. The NaCl toxicity did not substantially change with extended exposure periods from 4 to 12 wk, although the 4-wk EC20s for biomass were slightly greater (up to 37%) than the 12-wk EC20s in the 2 longer-term exposures. Including the toxicity data from the present study into existing databases would rank fatmucket the most sensitive species to KCl and the second most sensitive species to NaCl for all freshwater organisms. Environ Toxicol Chem 2018;37:3050-3062. Published 2018 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

Effect of landscape heterogeneity on termite tunnel pattern: Simulation study

Abstract Although the environment in which termites live is very heterogeneous, most experimental studies on the termite tunnel patterns have been conducted on homogeneous sand substrates. In order to explore how the heterogeneity affects tunnel patterns, I developed an agent-based model to simulate termite tunneling behavior at the individual level. In this model, grid space consists of easy and difficult areas for tunneling. Heterogeneity, H, was defined as the degree of the mixture of the two areas. The tunnel patterns formed by changing the number of termites, N, and H were quantitatively characterized by territory circularity and the territory area. These patterns were categorized into two groups, one with a small territory area and high circularity (group 1) and the other with a large area and low circularity (group 2). Considering the previous study that the termite populations with high N values have high territorial scalability, it can be said that the territories belonging to group 2 have higher foraging abilities and viability than those belonging to group 1. The simulation results showed that the tunnel patterns generated for small N and high H belonged to group 2. This implies that the heterogeneity can make a positive contribution to the expansion of the foraging area by effectively focusing the foraging energy of a termite population. I briefly discussed the mechanism of this positive role and the limitations of this simulation study. In addition, I discussed issues that need to be resolved in the near future to overcome the limitations.

Multidimensional Analysis Associated With Growth Analysis in the Selection of Organic Substrates for the Production of Tomato Seedlings

Tomato (Solanum lycopersicum L.) is a crop whose cultivation is of great importance in economic and social aspects. However, the development of efficient and low-cost technologies is essential for the growth of agricultural activity in the region. Among the most studied technologies, the production of quality seedlings in organic substrates is highlighted. In this context, the objective was to evaluate the development of tomato seedlings produced with organic substrates, using the decomposed stem of babassu palm and goat manure, using the multidimensional technique with the help of canonical functions associated with growth analysis. The treatments consisted of 25%, 50% and 75% sand aggregates, 25% to 50% sand addition, 25% to 50% sand and commercial substrate, established in a completely randomized design with 28 treatments and four replications in a 7 × 4 factorial scheme, the first factor consisting of seven substrates and the second of four evaluation periods (7, 14, 21, 28 days after emergence). Were analyzed shoot length and main root length; dry mass of the aerial part and of the root system and leaf area. These variables were analyzed through multidimensional analysis with the help of canonical functions and growth analysis. In general, the substrates consisting of goat manure and sand were superior to the substrates consisting of the decomposed palm tree stem and the commercial substrate. The alternative substrate formed by the mixture of goat manure, in the proportion of 25% of sterilized sand + 75% goat manure, constitutes the best option for the production of tomato seedlings.

Antifungal Activity and Phytotoxicity of Vitex simplicifolia Oliv. Leaves Essential Oil

Agriculture faces many difficulties related to phytopathogenic fungi leading to quantitative and qualitative losses of crops. The use of essential oils against these fungi is one of the alternatives. This study focused on the antifungal activity and phytotoxicity of Vitex simplicifolia Oliv. leaves essential oil. Firstly, we extracted the essential oil from the leaves by hydrodistillation. Subsequently, seven fungal isolates were evaluated for their sensitivity to the essential oil on Potato Dextrose Agar (PDA) media at 0.1; 0.25 and 0.50%. Evaluation of the phytotoxicity of the essential oil was performed on sorghum seeds on a sterilized sand substrate. At the seventh day after incubation, the most sensitive fungi to the essential oil are Fusarium moniliforme, Colletotrichum graminicola and Curvularia lunata. The most sensitive fungus to the essential oil at 0.50% is Colletotrichum graminicola with 77.21% inhibition rate at the seventh day after incubation. Phytotoxicity evaluation showed that for all biomass parameters measured there is no significant difference between treatment with the essential oil and treatment with the fungicide control. At the end of this study, it appears that Vitex simplicifolia essential oil has a high antifungal activity. This essential oil has not shown toxicity on sorghum growth parameters. Therefore, this oil can be used in organic farming.

Molecular diet analysis reveals predator-prey community dynamics and environmental factors affecting predation of larval lake sturgeon Acipenser fulvescens in a natural system.

This study utilized molecular tools to quantify the prevalence of predation during the vulnerable drifting larval life-history stage of lake sturgeon Acipenser fulvescens. How predators, the co-distributed prey community and abiotic environmental conditions (e.g., stream substrata) affected predation levels was quantified. Nightly D-frame drift net surveys were used to estimate the biomass of A. fulvescens and co-distributed prey. Gastrointestinal diet samples (n = 1,140) from 28 species of potential fish predators were collected during electrofishing surveys. Sampling was conducted for 17 days across 2015 and 2016. Based on DNA barcode analysis using sturgeon-specific mtDNA cytochrome oxidase I primers, A. fulvescens DNA was detected in 73 of 1,140 diet samples (6.40%) from 16 of the 28 predator species examined. A logistic regression model was used to analyse the effects of biotic and abiotic variables associated with the likelihood a predator had consumed larval A. fulvescens. Increasing lunar illumination and biomass of larval A. fulvescens increased predation rates on larval A. fulvescens. Higher discharge and greater biomass and proportions of alternative prey decreased predation rates of larval A. fulvescens. Predation rates were slightly higher in habitats with sand substrata. Most predator species preyed upon larval A. fulvescens at similar rates. The study revealed considerably higher incidence of predation on larval A. fulvescens than previous studies had documented using traditional morphological diet analysis. Co-distributed prey and abiotic environmental variables that affected the predation rates of a species of regional conservation concern can inform future management actions.

Effect of pH and Silicon in the Fertigation Solution on Vegetative Growth of Blueberry Plants in Organic Agriculture

The effect of pH and silicon (Si) in the nutrient solution on the vegetative development of 2-year-old blueberry plants (Vaccinium corymbosum L. cv. Ventura) was studied. Two independent experiments were performed on coir fiber (CF) and sand as substrates. In experiment 1, Si was applied in the nutrient solution at a dose of 0.0, 0.3, 0.6, and 1.2 mm. In experiment 2, plants were treated with nutrient solution at pH 4.00, 4.75, 5.50, and 6.25, using two sources of acidification: nitric acid and citric acid. The parameters of plant growth, foliar surface, and stem biomass were measured. With the application of 1.2 mm Si to CF, plant height registered a significant increase of 8%, and shoot dry and fresh biomass increased by 21% and 25%, respectively. The results of experiment 1 indicated that the application of Si benefits the vegetative growth of blueberry plants in CF, but no effect was observed in the sand substrate. In the results of experiment 2, the pH level of 6.25 in CF decreased the dry weight of stems and leaves by 21% and 18%, respectively. A significant increase in the pH range of 4.00 to 5.50 was recorded in both the citric acid and nitric acid treatments, but these significant effects were not found in sand. Citric acid presented a similar behavior to nitric acid, which indicates that it can be a good source of acidification in organic and ecologically friendly crops.

Water deficit increases the susceptibility of yellow passion fruit seedlings to Fusarium wilt in controlled conditions

Fusarium wilt is considered the main fungal disease of yellow passion fruit plants in Brazil. There is ample anecdotal evidence of greater intensity of Fusarium wilt after water shortage in field conditions, but this association needs scientific confirmation. There is also a need to increase the efficiency of inoculation with Fop (Fusarium oxysporum f. sp. passiflorae) under controlled conditions for research purposes. Therefore, in this study we evaluated the effect of propagation method (from cuttings or seedlings) associated with controlled water deficit on the incidence of Fusarium wilt in yellow passion fruit plants. The artificial inoculation with Fop involved application of a spore suspension of 106 conidia mL−1 and infestation of the potting media with Fop grown in sand and cornmeal substrate. For anatomical analysis, root segments were used from inoculated and non-inoculated plants (control). Seedlings that were submitted to water deficit presented the highest incidence of Fusarium wilt, 75.0%, while in the irrigated control the incidence was below 40.0%. The mortality associated with Fop in cutting-propagated plants did not differ from non-inoculated plants. The plants subjected to water stress had greater presence of hyphae and chlamydospores and reduced starch concentration in the root cortex region. Propagation by seeds associated with controlled water stress can be used to screen accessions of P. edulis for resistance to Fusarium wilt.

Physiological potential of soybean seeds over storage after industrial treatment

Abstract: The aim of this study was to evaluate the effect of industrial seed treatments on the physiological potential of soybean seeds over storage. Four mixtures of agrochemical products in association with two fertilizers were tested. The agrochemical product mixtures were carbendazim/thiram + imidacloprid/thiodicarb; pyraclostrobin, thiophanate-methyl, and fipronil; thiophanate-methyl/fluazinam + bifenthrin/imidacloprid; and metalaxyl-m/fludioxonil + thiamethoxam. The two fertilizers were 7% N, 16% P2O5, 0.6% Co, and 2.5% Mo; and 1% Co, 10% Mo, and 7% P2 O5. The experiment was carried out in a completely randomized design in a split-plot arrangement in time, with four replications. The treatments were allocated in the plots, while the storage periods (0, 30, 60, 90, and 120 days) constituted the split-plots. The following tests were carried out in each period: first count of germination, germination, accelerated aging, emergence speed index in sand substrate, and final seedling emergence in sand substrate. Seed germination and vigor declined over the storage period, especially after industrial treatment. Pesticide mixtures of a carbendazim/thiram fungicide base and an imidacloprid/thiodicarb insecticide base most impaired seed physiological potential throughout storage, regardless of fertilizer use in the industrial treatment.

Evaluation of the effects of onboard sorting and experimental holding practices on the post-catch survival of brown shrimp (Crangon crangon L.)

ABSTRACTEuropean brown shrimp (Crangon crangon) have great commercial value. Recently, an increasing demand for fresh shrimp has led fishermen to land part of their catch alive. In the present study, the effects of various parameters on the post-catch survival of brown shrimp were investigated by housing them in natural seawater and monitoring survival for two weeks. In a first experiment shrimp survival was tested under high population densities at different temperature settings ranging between 8°C and 21°C. A second experiment investigated the effect of a sand layer in the holding tanks when shrimp were housed at low population densities. Finally, the impact of onboard sorting with a rotary sorting riddle on subsequent survival was assessed. A higher survival rate was found at lower water temperatures. The use of a sand substrate did not significantly improve survival but did result in a more even distribution of shrimp across the bottom of the holding tanks. Onboard sorting with a mechanical rotary sorting riddle did not significantly affect the survival of brown shrimp during the first four days of holding although injuries sustained during onboard handling resulted in high mortality at the time of landing.

ANALYSIS OF BIODIVERSITY AND QUALITY OF METRO RIVER IN MALANG CITY (PLANKTON AND BENTOS BIOINDICATOR STUDY)

Metro River is a river that passes through Malang City and empties into Karangkates Dam. The increasing number of residents of Malang City resulted in more volume of waste water produced, and one of them is dumped on the Metro River. This affects the increasing pollution load received by the river so that it affects the decreasing of tamping capacity of river pollution load. Changes in water quality in rivers lead to changes in macrozoobenthic community composition. Therefore, it is necessary to monitor the quality status of Metro River by using macrozoobentos animals. The purpose of this research is to make the classification of Metro River based on macrozoobentos animal community in determining the water quality status of Metro River based on macrozoobentos and the classification of pollution level that happened. The research method is field observation, water quality measurement of Metro river and macrozoobentos sampling. The results showed that the distribution of macroinvetebrata in the Site of group of Banana Temple was from Gastropoda family, Leptophlebiidae, Chloroperliidae, and Baetidae on rocks with fast current velocity (1.02 m3 / s), 17-27 ° C, BOD level 3.7 mg / l, and COD content of 20.8 mg / l. While on the Site of group Merjosari, Karang Besuki, Bandulan and Sitirejo were found macrozoobentos from Chironomidae, Hydrop sychidae and Lumbri cullidae families, on the substrate of mud and sand, with slow flow rate (0.0052 - 0.0675 m3 / s), BOD 21, 8 - 45.7 mg / l, and COD content 107.8 -267.2 mg / l. The status of upper Brantas river waters determined by using the BMWP Index of the Pisang Candi, Merjosari, Karang Besuki, Bandulan and Sitirejo groups has medium gray water status with ASPT values ranging from 4 to 6.2. Keywords: macrozoobentos, Water Quality Status of River, BOD, COD

Identifying key habitat and spatial patterns of fish biodiversity in the tropical Brazilian continental shelf

Knowledge of the spatial distribution of fish assemblages biodiversity and structure is essential for prioritizing areas of conservation. Here we describe the biodiversity and community structure of demersal fish assemblages and their habitat along the northeast Brazilian coast by combining bottom trawl data and underwater footage. Species composition was estimated by number and weight, while patterns of dominance were obtained based on frequency of occurrence and relative abundance. A total of 7235 individuals (830 kg), distributed in 24 orders, 49 families and 120 species were collected. Community structure was investigated through clustering analysis and by a non-metric multidimensional scaling technique. Finally, diversity was assessed based on six indices. Four major assemblages were identified, mainly associated with habitat type and depth range. The higher values of richness were found in sand substrate with rocks, coralline formations and sponges (SWCR) habitats, while higher values of diversity were found in habitats located on shallow waters (10–30 m). Further, assemblages associated with sponge-reef formations presented the highest values of richness and diversity. In management strategies of conservation, we thus recommend giving special attention on SWCR habitats, mainly those located on depths between 30 and 60 m. This can be achieved by an offshore expansion of existing MPAs and/or by the creation of new MPAs encompassing those environments.

Morfoanatomía de las plántulas de dos especies de lupinos graníferos: Lupinus albus y L. angustifolius (Fabaceae, Faboideae)

The morphoanatomy of seedlings of two cultivated grain lupines is described and compared ( Lupinus albus L. and L. angustifolius L.). To obtain the seedlings, 60 seeds of each species were sown in terrines with a coarse sand substrate. After 20 days from sowing, 15 seedlings were selected and the lengths of hypocotyl, epycotyl were measured as well as, the length and width of leaflets, which showed significant differences except in the lengths of the leaflets. Optical microscope slides were done for the epidermis and cross-sections of primary root, hypocotyl, epycotyl, petiole and leaflet, the sections were analyzed, illustrated and photographed. Both species share the same structure of diarch root, glabrous adaxial face and anfistomatics characteristics with anomocytic stomata in leaflets epidermal layers. The most noticeable differences between the species seedlings are the presence of a laminar collenchyma layer and the larger number of vascular bundles in the hypocotyl and epycotyl of L. angustifolius and a starchy layer sheath in the hypocotyl of L. albus . The cordate form and the two lobes emerging from a center channel in the petiole of L. angustifolius, reaffirm other morphological similarities with the species L. gibertianus . The major differences in the leaflets are the width and the structure of the mesophyll which is dorsiventral in L. albus and is isobilateral in L. angustifolius . The structure of an epitricopodium in tricelular trichomes are described for the first time for the genus Lupinus . The anatomical structures were com- pared and discussed with those of other species of the genus, with environmental conditions and with modifications by plant breeding. This work serves as a basic knowledge for further research to find if there are relationship between support tissues and transport system with the plant protection strategies against pathogen infections and water stress.

Imaging analysis of biological soil crusts to understand surface heating properties in the Mojave Desert of California

Biological soil crusts (biocrusts) are composed of a combination of cyanobacteria, green algae, lichens, and mosses that can protect arid soil surfaces from erosive forces. The presence of biocrusts in desert regions is influenced by a complex interaction of climatic, edaphic, and topographic variables, but their distribution and coverage densities in southern California deserts are not precisely mapped. Visible satellite bands (red-green-blue; RGB) and infra-red image resolution are generally too coarse to distinguish between biocrusts and their interstitial sand substrates, limiting most remote sensing analysis of these soil biotic assemblages. The purpose of this study was to better understand the relationships between biocrust cover, surface coloration and roughness, and the thermal infra-red (TIR) emission properties of biocrusts to determine if new types of imaging of desert surfaces could be used to more accurately detect biocrust presence. Based on the results from megapixel digital photos and TIR imaging for nearly 130 different, well-developed biocrust surfaces in the Mojave and Lower Colorado Deserts of California, we designed laboratory heating experiments to test the effect of biocrust cover on the heating properties of sandy wash habitats. Biocrust samples collected from the field were subjected to artificial heating and cooling to simulate the Mojave Desert diurnal cycle. We used image segmentation algorithms to separate true-color biocrust images from their sandy substrates, and to map the heating and cooling patterns of these surfaces with different levels of biocrust coloration and roughness. The major findings of this study showed that biocrust patch images in the field had Red texture mean values between digital numbers of 95 and 131 with moderate positive tail shewness levels, indicative of a highly rugose surface of the biocrust cover. Such patches were also well-compacted overall, with moderate skewness toward negative tails. In controlled laboratory temperature experiments to simulate the desert diurnal cycle, surface wetting with a fine mist of water resulted in significantly lower peak surface temperatures of biocrust samples compared to dry biocrust heating results of the same crust and sand samples. The findings of this study can improve future mapping for lichen-dominated biocrust surfaces in the Mojave Desert.

Growth of the Aquatic Plant Southern Naiad in Varying Percentages of Sand and Controlled-release Fertilizer

Native aquatic plants are important to maintaining a balanced ecosystem, but they often are displaced by exotic invasive plant species. The research on the control and growth of the invasive aquatic species hydrilla (Hydrilla verticillata) using sand substrates and controlled-release fertilizers (CRF) provides a potential production technique for other aquatic plants. We questioned if we could use hydrilla production techniques to grow southern naiad (Najas guadalupensis), a Florida-native aquatic plant that is often mistaken for hydrilla. We grew southern naiad cuttings in containers filled with 100:0, 75:25, 50:50, 25:75, or 0:100 coarse builder’s sand and sphagnum moss (by volume). Before planting, containers were fertilized with 0, 1, 2, or 4 g·kg−1 CRF (15N–4P–10K). Containers were submerged in large storage tubs filled with rainwater and grown for 8 weeks. Southern naiad shoot dry weight was greater in the 100% sand substrate than that in the 0% sand substrate. Substrate electrical conductivity (EC) levels were greater in the 0% sand with no difference among the other substrates. Shoot and root dry weight of plants fertilized with 1–2 g·kg−1 CRF were greater than 0 or 4 g·kg−1 CRF. Substrate EC also increased as fertilizer rate increased, with the highest EC observed at 4 g·kg−1 CRF. Based on our results, we would suggest growing southern naiad in substrates with 100% sand and fertilized with 1–2 g·kg−1 CRF.