Clumps Of Plants Research Articles

KERAGAAN PENYAKIT PADI PADA VARIETAS UNGGUL BARU UNTUK AGROEKOSISTEM RAWA DAN LAHAN KERING

<p><em>Swampand dryland agroecosystems has the potential tobe used as acomplementary effort to improve national food security. This effort washamperedby the disruption of plant disease in new improved varieties of riceasone of the technology to increase rice production. This study aims to determine the performance of rice diseases at new improved varieties for swamp and dryland agro eco systems. Research conducted in 2013 growing season in ICR Rusinga randomized block design with 3 replications. The treatments were13new improved varietiesi.e. Inpara 1, Inpara 2, Inpara 3, Inpara 4, Inpara 5, Inpara 6, Inpara 7, Inpago 4, Inpago 4, Inpago 5, Inpago 6, Inpago 7, Inpago 8, and Inpago 9. For disease survei llance drawn diagonalline in each experimental plot, each diagonalline taken10 samples of plant clumps. Each sample clumps was observed the disease severity that were found by scoring method (IRRI, 2002).The results showed there were six diseases that infect new improved varieties for swampand upland agro ecosystems name lystem rot, sheath blight, red stripe, cercosporaleaf spot, bacterial leaf blight,and bacterialleafstreak. Stem rot with the highest severity found in Inpara3(35.18%) and Inpago4(32.96%). Sheath blight with the highest severity found in Inpara1(6.11%) and Inpago7(5.74%). Red stripe withthe highests everity found in Inpara6 (47.78%) and Inpago9 (40.74%). Cercosporaleaf spotwiththe highestseverity found in Inpara5(40.37%) and Inpago6 (14.82%). Bacterial leaf blight with the highest severity found in Inpara3(24.26%) andInpago9 (32.04%). Bacterial leaf streak with the highest severity found in Inpara3(9.26%) and Inpago6 (30.56%).</em></p><p> </p>

Why mistletoes are more aggregated in disturbed forests? The role of differential host mortality

Mistletoes rely on biotic seed dispersal to ensure their recruitment on appropriate host plants, as their seeds must be deposited on safe sites to allow attachment. As most host-parasite systems, mistletoe’s spatial distribution depends on the spatial arrangement of the hosts and on the seed disperser’s behavior. We used the mistletoe Tristerix corymbosus, which is solely dispersed by the arboreal marsupial Dromiciops gliroides, and it is capable to parasitize a wide range of hosts. We previously found T. corymbosus mistletoes to be more abundant and densely aggregated in disturbed habitats, compared to neighboring native forests, at similar levels of disperser abundance and host availability. To explain this pattern, we tested two non-mutually exclusive hypotheses: (1) the larger resource availability in disturbed habitats modify the disperser behavior reducing its home range, and (2) plant species in disturbed habitats are better hosts and offer higher survival probabilities. We sampled 300 mistletoes (98 at the native forest and 202 at the disturbed habitat), which were followed from November 2011 to March 2015 for estimating survival rates and conducting point-pattern analyses. Besides, we tracked ten Dromiciops gliroides individuals using VHF telemetry at both habitats to estimate the home range areas in the two habitats. Mistletoes were aggregated in both habitat types, being stronger at the disturbed habitat with dense plant clumps. Besides, no differences were found on home range of individual D. gliroides between habitats despite structural and resource availability differences. However, mistletoe survival significantly differed between habitats, as mistletoes had a survival probability of 82.87% at the disturbed habitat, whereas survival probability at the non-disturbed habitat was 53.33%. The most common host species at the non-disturbed habitat is Pluchea absinthioides, a seasonal shrub where mistletoes had a survival probability of 29%. At the disturbed habitat, however, the most common hosts are the shade-intolerant shrubs Aristotelia chilensis and Rhaphithamnus spinosus, which had very low mortality rates. The aggregation pattern found at the disturbed habitat is likely to emerge from differential host mortality rather than behavioral changes on the seed disperser vector.

Population dynamics of Pulsatilla patens (L.) Mill. in a new locality in Poland

Abstract A new locality of Pulsatilla patens (L.) Mill. in the Wyszków-Jegiel Forest District, in the southern part of Puszcza Biała (ATPOL EC79) is described. This locality is situated on an escarpment, at the edge of Peucedano-Pinetum fresh pine forest with elements of Serratulo-Pinetum mixed pine forest and Potentillo albae-Quercetum steppe oak forest. Good light conditions prevail in the place of plant occurrence. Studies carried out in 2008-2015 showed an increasing trend of P. patens population, though, recently, this population seems to be stable. The number of species accompanying the pasque-flower also increased in this time period. It was found based on the analysis of flora directly neighbouring the clumps of the pasque-flower. During 7 years, the number of taxa increased by 31.5% on plot I and by 25% on plot II. In the years 2011-2013, the pasque-flower was represented both by flowering (1-2) and vegetative individuals. Afterwards, the plant was present only in vegetative stage. The number of its leaves varied in time. The highest number of leaves - 14 per individual - was noted in 2014, and the lowest number (1) - in 2012. The reason for a decline in the number of plant clumps in the site Dalekie and, at the same time, the greatest threat was the excavation of sand from the escarpment. In 2012, this escarpment slid down and several clumps of the pasque-flower were destroyed. Forest management and digging up by wild boars were additional factors limiting the population. To preserve the site of P. patens, measures of active protection should be applied.

HYDROMORPHOLOGICAL EFFECT OF INTRODUCING SMALL WATER STRUCTURES IN RIVER RESTORATION – THE EXAMPLE OF PBHS IMPLEMENTATION

The work attempts to determine the impact of small hydrotechnical structures on channel hydromorphology as a measure of river restoration. The experiment was set up in Flinta River in Polish lowland where extensive hydromorphological survey was competed. At the first stage of restoration project containers filled with plant clumps working as sediment traps (plant basket hydraulic structures – PBHS) were introduced. Those structures were relatively small but at the same time, large enough to change the river flow efficiently – working like low crested weirs. Two year monitoring program provided information about the impact of introducing such structures on river morphology and explained the PBHS impact on flow pattern of the river.

Factors influencing egg parasitism in sub-social insects: insights from the treehopperAlchisme grossa(Hemiptera, Auchenorrhyncha, Membracidae)

Subsocial insects rely on maternal care in order to enhance offspring survival. Subsocial Hoplophorionini treehoppers defend their egg masses from predatory and parasitoid attacks. Egg parasitic wasps are important enemies of the Membracidae. We examined parasitism patterns and female defence mechanisms in the Hoplophorionini treehopper Alchisme grossa (Fairmaire). We examined the effect of aggregations of egg-guarding females, spatial aggregations of host plants and female A. grossa, and host plant identity on the incidence of egg mass parasitism. Additionally, we measured the effect of female maternal care strategies on reducing the amount of parasitism on their egg masses. Aggregation of egg-guarding females on a single host plant was the most important factor affecting egg mass parasitism. Increased numbers of aggregated females lowered both parasitism risk and parasitism levels on their egg masses. When spatial clumping of host plants and egg-guarding females occurred simultaneously, parasitism risk was also reduced. Maternal care strategies such as coverage of the egg mass by the females' pronota and intensity of female defensive behaviour also seemed to lower parasitism on egg masses. A reduction of parasitism by female aggregation on host plants can be explained by a selfish herd dilution effect. This dilution effect was potentiated by a possible cooperation between aggregated egg-guarding females on the host plant. The present study provides a new dimension to sub-sociality in Hoplophorionini treehoppers.

Vegetation succession on Mt. Kenya in relation to glacial fluctuation and global warming

AbstractQuestionsHow has the Mt. Kenya plant community responded to recent glacial retreat? Has the recent glacial retreat been affected by increases in temperature? How have number of plant clumps and proportion of vegetation cover changed with distance from the glacier edge (i.e. till age)?LocationFrom Tyndall Tarn to the foot of Tyndall Glacier of Mt. Kenya (0°6′ S, 37°18′ E), Kenya.MethodsThe topography, soils, vegetation and glacial distribution around the Tyndall Glacier of Mt. Kenya were investigated from 1992 to 2011. The effect of glacial retreat on the rate of movement of leading edge (upper distribution limit) of plant species was examined. The distribution of vegetation was examined in a permanent plot that was surveyed in 1996 and 2011. The effects of temperature variation on glacial retreat were assessed with a least squares regression model.ResultsTyndall Glacier retreated at a rate of ~3 m·yr−1from 1958 to 1997, which increased to 7–15 m·yr−1between 1997 and 2011. The leading edge ofSenecio keniophytum, the first pioneer species to establish after glacial retreat, advanced with glacial recession. It was sparse in 1996; by 2011, the number of clumps and proportion of cover had increased. Clump size was affected by distance from the glacier edge (i.e. till age) in areas of recent deglaciation but not in deglaciated areas >15 yr old. Monthly mean minimum temperature at Mt. Kenya increased by >2 °C from 1963 to 2011, and glacial retreat was related to increase in monthly mean minimum temperature.ConclusionThe glaciers on Mt. Kenya have diminished rapidly in recent years, and pioneer plant species have advanced in response. The movements of some species do not appear to be directly spatially related to glacial retreat but may be related to increases in air temperature, soil development, seed dispersal limitation and interval of masting. Recent unusually high temperatures and precipitation also likely caused the blooming of some species during atypical seasons.

Emerging roles of mistletoes in malignancy management.

Mistletoes are a group of obligate plant semi-parasites in the order Santalales. These clumps of plants growing on a wide range of host plants have been traditionally regarded as medicinal repositories. However, current scientific discoveries have validated their health potentials like never before. Their extracts containing alkaloids, viscotoxins, lectins, and polysaccharides have been evidenced to possess a myriad biological potentials including cancer inhibition. Mistletoes have emerged as promising alternative therapy against colon, oral, lung, and pancreas cancers. The plant extracts bolster immunity, delay tumour initiation and progression, kill malignant tumours, stabilize DNA, alleviate side effects of chemotherapeutics, improve the lifespan, and coping ability of cancer patients and survivors. A range of proprietary formulations viz. Iscador, Eurixor, Helixor, Lektinol, Isorel, Iscucin, Abnoba-viscum and recombinant lectin ML-1 are already being commercialized. This review presents an informative account on the recent developments in mistletoe-mediated cancer management. The underlying mechanisms, possibilities and limitations in cancer therapeutic development are outlined for kindling both researcher and public interest.

Biologi Perbungaan Keladi Tikus (Typhonium flageliforme): Seludang Bunga Menghambat Penyerbukan?

A study on the flower biology on keladi tikus (T. flageliforme) was conducted to uncover if its spathe inhibitspollination from external pollen resources and causes very low fruit set. The spathe box closely envelopes thesexually vital properties of its inflorenscence. Observation was carried out on some plant clump grown on someuniform potting. A hole was made with scalpel about 4 x 5 mm on a side of the spathe to break its isolation. Somenearer flowers in same clump were left without treatment at all as experimental control. Parameter observed waspresence or absence of seeded fruit setting on spadix. The study result showed that almost all treated flowerspadix per potting, set seeded fruits significantly higher (63, 69 ± 37, 64) than that of controls (3, 57 ± 9, 45) so it isa great possibility that spathe can inhibit partially fruit set. Flower structure and its reproductive phenology werealso described.

Dominant network interactions are not correlated with resource availability: a case study using mistletoe host interactions

Network theory in ecology has been central to understanding species co‐occurrence patterns, specialization and community stability. However, network theory has traditionally focused on the ‘higher’ trophic level where exploitation of network ‘partners’ (i.e. individual interactions in response to resource availability) have remained underappreciated. In this study we tested how clumping and host availability influenced mistletoe–host interactions in a semi‐arid woodland, central Australia. We used a hierarchical approach that evaluated individual interactions by modifying the traditional randomization technique to simulate clumping and host exploitation. Using published literature we then compared our results with mistletoes from other genera. We found that mistletoes clump on fewer trees than predicted, even though interaction strength was no different from random expectations, and we found no evidence that common trees were heavily infected as predicted by the host availability hypothesis. The rate of host exploitation (measured as the proportion of trees infected) in semi‐arid Australia is similar to that for mistletoe genera in other parts of the world. We hypothesize that specific host trees act as a focal point for infection that facilitates the spread and overall population size of mistletoes. Overall our results indicate that resources, such as the number of trees in a mistletoe network, are less important than clumping of individual plants. We suggest that exploitation of available resources may play a similar role in other networks that extend beyond antagonistic relationships such as parasite or herbivore interactions.

Paleozoic mosses: Small, but no longer inconspicuous

The next time you stroll in a wooded area and spot small, green clumps of soft-looking plants, perhaps next to a rotting log or near the bank of a stream, you will probably have found one of several tens of thousands of species of mosses. Today these plants frequent moist areas that extend from the

Distribution and host specificity of the thistle‐feeding tortoise beetle Cassida vibex (Coleoptera: Chrysomelidae) in southwestern Hokkaido, northern Japan

AbstractThe thistle‐feeding tortoise beetle Cassida vibex (Coleoptera: Chrysomelidae) is widespread in the Palearctic region. In Japan, this species has been recorded only from the largest island, Honshu. Here we report the occurrence of this species on Hokkaido, the most northern main island of Japan, along with detailed distributional records from the southwestern part of the island (southern Oshima Peninsula) and information on host plants. We also present the results of laboratory experiments on adult feeding preference and larval developmental performance to determine the specificity of C. vibex for four thistle species (Cirsium grayanum, Cir. alpicola, Cir. yezoense and Cir. aomorense; Asteraceae) common in southwestern Hokkaido. Cassida vibex was detected at only four sites among 97 sites investigated on the Oshima Peninsula, in strong contrast to the common occurrence of the congeneric thistle feeder C. rubiginosa (74 of 97 sites). Cassida vibex was found mainly on Cir. alpicola in the wild, but adult beetles showed no feeding preference for this or three other thistle species when given a choice in the laboratory. Larval performance of C. vibex was similar on Cir. alpicola, Cir. yezoense and Cir. aomorense but significantly lower on Cir. grayanum. Since Cir. alpicola often forms large clumps of individual plants, whereas Cir. yezoense and Cir. aomorense are scattered in their habitats, and C. vibex was collected only at sites where there were dense patches of Cir. alpicola, we postulate that the persistence of C. vibex is possible only where a substantial amount of suitable host plants is available.

Reproduction reduces photosynthetic capacity in females of the subdioecious Honckenya peploides

As a consequence of the different reproductive functions performed by the sexes, sexually dimorphic/polymorphic plants may exhibit gender-related variations in the energy and resources allocated to reproduction, and in the physiological processes that underlie these differences. This study investigated whether the sexes of the subdioecious plant Honckenya peploides differ in ecophysiological traits related to photosynthetic capacity and whether possible differences depend on reproductive status and on the plant’s position (edge or centre) in the population. We registered in three sites in NW Spain, the sex and density of shoots of two segregated clumps of plants. These clumps represent an extreme case of sex-ratio variation across space, with separated single-sex clumps of plants. In two of these sites we measured photosynthetic efficiencies, chlorophyll content, and specific leaf areas. In females, reproduction reduced photochemical efficiency, chlorophyll content and increased the specific leaf area, which is a key leaf trait related to photosynthetic capacity. In males, no differences due to reproduction were detected. The position within the clump affected the specific leaf area of the shoots, with shoots growing at the edge having the lowest values, regardless of the sex. Finally, the effects of position in photosynthetic efficiency and chlorophyll content where highly variable among clumps. We conclude that the differential effects of reproduction on sexes may entail different costs that could be crucial in the outcome of interactions between them, contributing to their spatial segregation.

Flow characteristics within different configurations of submerged flexible vegetation

Summary The effects of three configurations (aligned, staggered, and columnar) of submerged flexible vegetation on flow structure are investigated experimentally in the laboratory. Time-averaged flow velocity and turbulence behavior are evaluated at different positions in each configuration by using a 3D acoustic Doppler velocimeter (ADV). According to the hydrodynamic regimes in experimental results, the vertical distribution of streamwise velocity can be separated into three layers—the upper non-vegetated layer, middle vegetation layer, and lower sheath layer. This three-layer model, which is associated with different logarithmic equations, can be applied to describe the vertical distribution of streamwise velocity. The local maximum velocity within vegetation occurs at the sheath section of a plant clump (0.10–0.15 vegetation height ( H v )) where the frontal width is minimal. Turbulent intensities in the streamwise ( u rms ) and spanwise ( v rms ) directions peak at the sheath section and at the approximate top of the canopy (0.9 – 1.2 H v ). The maximum Reynolds stresses exist at roughly 0.9 – 1.2 H v , which may be migrated vertically as the frontal width of a plant clump is increased. This high frontal width also increases streamwise velocity above vegetation, leading to increase variations in Reynolds stresses around the canopy top. On the vertical turbulent velocity scale ( w rms ), the vortices above a still canopy rotate faster than those above a waving canopy. Therefore, the experimental results demonstrate that the flow field can vary significantly at the sheath section and at the top of a plant clump due to altered flow pass. These analytical findings will likely prove useful when designing ecological habitats and preventing riverbed erosion.

Short communication: Engineering properties of wetland plants with application to wave attenuation

This technical note presents empirically-derived values for biophysical attributes of several commonly occurring wetland plant species, including plant stem diameter and tapering, plant clump and stem spacing statistics, biomass, Young's modulus of elasticity, and bending strength. These parameters can be used to more realistically configure plant canopies in numerical and laboratory studies to further our understanding of wave attenuation by wetlands.

Significance of the tropical fire ant Solenopsis geminata (hymenoptera: formicidae) as part of the natural enemy complex responsible for successful biological control of many tropical irrigated rice pests

The tropical fire ant Solenopsis geminata (Fabricius) often nests very abundantly in the earthen banks (bunds) around irrigated rice fields in the tropics. Where some farmers habitually drain fields to the mud for about 3-4 days, the ants can quickly spread up to about 20 m into the fields where they collect food, including pest prey such as the eggs and young of the apple snail Pomacea caniculata (Lamarck) and insects such as lepidopterous larvae and hoppers, notably Nilaparvata lugens (Stäl) the brown planthopper (Bph) and green leafhoppers Nephotettix spp. Even in drained fields, the activity of S. geminata is restricted by rainfall in the wet season. The relatively few ant workers that forage characteristically into drained fields and on to the transplanted clumps of rice plants (hills) kill the normally few immigrant Bph adults but are initially slower acting than other species of the natural enemy complex. However, larger populations of Bph are fiercely attacked and effectively controlled by rapidly recruited ant workers; whereas, in the absence of the ant, the other natural enemies are inadequate. In normal circumstances, there is no ant recruitment in response to initially small populations of immigrant Bph and no evidence of incompatibility between ant foragers and other natural enemies such as spiders. However, when many ants are quickly and aggressively recruited to attack large populations of Bph, they temporarily displace some spiders from infested hills. It is concluded that, in suitable weather conditions and even when insecticides kill natural enemies within the rice field, periodic drainage that enables S. geminata to join the predator complex is valuable for ant-based control of pests such as snails and Lepidoptera, and especially against relatively large populations of Bph. Drainage practices to benefit ants are fully compatible with recent research, which shows that periodic drainage combats problems of 'yield decline' in intensively irrigated tropical rice and is also needed in South East Asia to make better use of seriously declining water supplies for irrigation.

Sieving crusts and macrofaunal activity control soil water repellency in semiarid environments: Evidences from SE Spain

Quick overland flow peaks observed in runoff hydrographs from rainfall experiments carried out on mica schist soils in Rambla Honda (SE Spain) suggest development of soil water repellency (SWR). In order to spatially characterize its occurrence and severity and the factors controlling it, potential water repellency was measured in 120 soil samples using the WDPT test at laboratory conditions. Actual water repellency measurements were additionally performed at field conditions in order to increase our knowledge about the occurrence of this phenomenon. Samples were taken in bare soils ( n = 23), beneath plant clumps of Retama sphaerocarpa ( n = 23) and Anthyllis cytisoides ( n = 10) and from soils affected by rabbit latrines ( n = 9). Soil organic matter was also determined in 47 selected samples with a broad range of potential water repellency values. Results indicate that occurrence of SWR in Rambla Honda (potential water repellency values) varies in the three soil dimensions, areal and depth. The areal variation is due to the patchy pattern of organic matter and the variation with depth of the washed-in layer of sieving crusts developed in colluvial and alluvial soils after abandonment by agriculture. These layers act as physical barriers that restrict or impede the translocation of hydrophobic compounds to deeper layers. Such three-dimensional heterogeneity stresses the importance of the sampling scheme used for adequate SWR assessment. The severity of water repellency is generally reduced in this area because of the relatively scarce organic matter content and its spatial variability. A weak exponential relationship was found between the severity of potential water repellency and total organic carbon ( r 2 = 0.38; p-value < 0.01). Extreme values of actual and potential water repellency were found in rabbit latrines, stressing the importance of macrofauna in its development. Water repellency has an important impact on the local hydrology controlling runoff–runon between vegetated and bare patches, and possibly flash flooding during heavy rains in early autumn or after long dry periods. Review of a series of runoff hydrographs from previous rainfall simulations has distinguished four types of runoff patterns based on the occurrence of SWR.

Spatial structure and diversity of woody plants and ectomycorrhizal fungus sporocarps in a natural subtropical forest

Spatial patterns of ectomycorrhizal fungi, ectomycorrhizal plants, and non-ectomycorrhizal plants were investigated in a natural subtropical forest using second-order analysis. The results of spatial pattern analysis showed that the degree of clumping of woody plants and ectomycorrhizal sporocarps were correlated. There was a significantly positive correlation of relative aggregation indices between ectomycorrhizal fungi and both non-ectomycorrhizal trees and ectomycorrhizal saplings. Correlations between percentage of ectomycorrhizal trees and sporocarp occurrence of ectomycorrhizal fungi and between diversities of woody plants and ectomycorrhizal fungi were distance-dependent or scale-related. A significantly high percentage of ectomycorrhizal trees was found only at relatively short distance from ectomycorrhizal fungal sporocarps, and significantly positive correlation of the diversity between woody plants and ectomycorrhizal fungi was found only at relative long distance, which implied that ectomycorrhizal sporocarps prefer ectomycorrhizal-tree-dominant micro-sites at near distances and at relatively large scales, diverse ectomycorrhizal sporocarps could be found in woodlands with high diversity of woody plants. Important factors affecting the spatial distribution, occurrence, and diversity of ectomycorrhizal fungi include spatial pattern of ectomycorrhizal plants and non-ectomycorrhizal plants, percentage of ectomycorrhizal plants, and plant diversity in a natural forest.

Biocontrol and epidemiology of lettuce drop caused bySclerotinia minorat Bacchus Marsh, Victoria

The mycoparasite Coniothyrium minitans, but not a commercial preparation of Trichoderma or a local isolate of Trichoderma virens, significantly increased the percentage of sclerotia infected and reduced the percentage viability of sclerotia when applied to lettuce plants showing the earliest symptoms of lettuce drop caused by Sclerotinia minor in commercial crops. C. minitans always infected untreated controls in these experiments and was evidently a natural resident in the soils; it is likely that it effects a degree of natural biocontrol of sclerotia of S. minor in these soils. In spring and summer, the viability of untreated sclerotia among plant debris on the surface of the soil declined greatly, providing evidence that prolonging the exposure of sclerotia on the soil surface before cultivation for the next crop can greatly reduce sclerotial inoculum. Far fewer sclerotia were formed on infected, untreated plants in late spring to summer than in autumn and early spring. Epidemics of lettuce drop caused by S. minor on salad lettuces developed rapidly in the last 1 or 2 weeks before harvest. This was as a result of infection mainly via the lower leaves drooping onto the surface of the soil or touching adjacent infected plants. Clumping of diseased plants was evident only late in the epidemic. Cutting of infected mature plants at an early stage of symptom development and leaving them in the field did not reduce the number of sclerotia formed on them compared to plants left in the ground, indicating that cut plants should be removed from the field. Possibilities for disease control are discussed.

Do plant clumps constitute microbial hotspots in semiarid Mediterranean patchy landscapes?

Three semiarid Mediterranean patchy landscapes were investigated to test the existence of a microsite effect (i.e. plant canopy vs. inter-canopy) on soil microbial communities. Surface soil samples were independently taken from both microsites under naturally changing conditions of humidity and temperature through the year. In gypsiferous soils covered with a shrub steppe, improved physical and chemical soil properties were registered underneath the plant canopy, where the densest and most active microbial communities were also detected (e.g. microbial biomass C averaged 531 and 202 mg kg −1 in canopy and inter-canopy areas, respectively). In calcareous perennial tussock grasslands, either growing on soils over limestones or alluvial deposits, the microsite effect was not so marked. Soil humidity, temperature and total organic C were homogeneously distributed over the landscape conditioning their uniform microbial activity under field moisture conditions (ATP content averaged 853 and 885 nmol kg −1 in canopy and intercanopy areas, respectively). However, readily mineralizable C and microbial biomass C were preferentially accumulated in soils underneath the tussocks determining their larger potential microbial activity (e.g. C hydrolysis capacity under optimal conditions). In conclusion, plant clumps either functioned as microbial hotspots where enhanced microbially driven ecosystem processes took place or as microbial banks capable of undergoing a burst of activity under favourable climatic conditions. Our results provide experimental evidence of a non-patchy distribution of certain soil microbial properties in semi-arid Mediterranean patchy ecosystems.

Beyond Water Harvesting: A Soil Hydrology Perspective on Traditional Southwestern Agricultural Technology

This article presents a hypothetical, general model that describes the processes involved in one aspect of traditional Southwestern agriculture: the interactions between soil hydrology and farming technology. In conjunction with extensive participation in hand cultivation with Hopi farmers, studies of soil hydrologic processes in Hopi maize fields have identified hydrological processes directly linked to Hopi field location criteria and farming practices. Field location criteria select for locations where soil textures and soil profile heterogeneity control rates of moisture infiltration, as well as loss to runoff, bare soil evaporation, and drainage. Farming practices, including clearing, maintenance, plant spacing, seed depth, and planting pit morphology, operate in conjunction with soil profile attributes to increase the amount of moisture available to plants and the mobility of that moisture. Effects of both soil profile attributes and farming practices are integrated into the discrete soil volume model of hydrologic processes occurring in the basic unit of Hopi farming, the individual plant clump. This information provides basic insights on ways archaeologists might evaluate the productive potentials of soils, the extent of farmable land around prehistoric communities, and the ranges of climate conditions that permit crop growth on that land.