100-m Plot Research Articles

Soil organic carbon and nutrient characteristics of Anogeissus groves in old Opara forest reserve, Nigeria.

Forest-savanna transition zones of West Africa are uniquely characterized by forest groves, forest patches, or forest islands, the importance of which for sustainable resource management and their potential for carbon sequestration and nutrient cycling is often underrated. Our study conducted a comparative analysis of the soil organic carbon and nutrient characteristics of the Anogeissus groves in the old Opara forest reserve and their adjoining arable lands. We established 30 sampling frames of 100m × 100m plots with 15 frames per land use type. For each sampling frame, six observation points were randomly selected, and composite soil samples were collected at soil depths of 0-20cm and 20-50cm per observation point. Our results showed Anogeissus groves and their adjoining arable lands to exist on similar landscapes while the groves have enriched soil morphological characteristics (e.g., soil color), higher soil organic carbon (SOC), and better nutrient characteristics. There were strong positive relationships between SOC, effective cation exchange capacity, total nitrogen, calcium, magnesium and calcium, zinc, electrical conductivity, and copper. The significant soil organic matter accumulation in the groves accounts for the overall improved soil characteristics over the adjoining arable lands. Preserving the groves and similar Africanecosystems may be important in climate regulation, resources and biodiversity conservation, and ethnopharmacology for rural communities. Thus, a question arises: should more land be set aside for ecological conservation or for agricultural productivity?

Potential Seed Source for the Preservation of Bitti (Vitex cofassus) in the Community Forest of Burau District, South Sulawesi, Indonesia

Bitti (Vitex cofassus) is one of the most important tree species in Sulawesi, or in some areas, it is also known as gofasa. Bitti wood is also widely used for other uses, such as building timber and carpentry wood. This study aimed to determine the potential source of beetroot (Vitex cofassus) seeds in the Community Forest of Burau Village. This study used the exploratory method by making plots using purposive sampling on a 100m x 100m plot with 38 sampling plots.. Data analysis of potential beetroot seed sources includes measuring diameter, tree height, tillering potential, and determining scoring based on the presence of seeds to determine the possibility of Bitti tree seeds. The results of this study showed that the phenotypic characteristics of the 18 plots that had been selected were a total diameter of 524.44, an entire tree height of 272 m, and a branch-free height of 50.5 m of the 18 parent trees that have been identified, then selected with the criteria of having fruit and saplings. Bitti trees have the most significant tillering potential, found in plot 21 with 0.005% of tillers and 0.0097% of the fruit. Other results obtained the highest value in the parent tree with a score of 73 with a potential class of 5. Genetic and environmental factors can affect plant growth, so the selection of seed source trees to get Bitti mother plants with good phenotypic quality will produce quality seeds.

Diversity and regeneration status of tree species in Binsar Wildlife Sanctuary, Uttarakhand, India

We assessed tree species diversity and regeneration status in the Binsar wildlife sanctuary, Uttarakhand. Six major forest sites were selected for sampling ranging from 1600-2400m asl in north and south aspects. In each forest stand a 100 x 100m plot was laid and trees, saplings and seedlings were recorded following standard ecological methods.The overall tree density ranged from 663 to 1066 individuals ha-1 among the identified forest communities and total basal area from 40.24-71.20 m2 ha-1. Good regeneration was observed in higher altitudinal community.

Tree Crowns Cause Border Effects in Area-Based Biomass Estimations from Remote Sensing

The estimation of forest biomass by remote sensing is constrained by different uncertainties. An important source of uncertainty is the border effect, as tree crowns are not constrained by plot borders. Lidar remote sensing systems record the canopy height within a certain area, while the ground-truth is commonly the aboveground biomass of inventory trees geolocated at their stem positions. Hence, tree crowns reaching out of or into the observed area are contributing to the uncertainty in canopy-height–based biomass estimation. In this study, forest inventory data and simulations of a tropical rainforest’s canopy were used to quantify the amount of incoming and outgoing canopy volume and surface at different plot sizes (10, 20, 50, and 100 m). This was performed with a bottom-up approach entirely based on forest inventory data and allometric relationships, from which idealized lidar canopy heights were simulated by representing the forest canopy as a 3D voxel space. In this voxel space, the position of each voxel is known, and it is also known to which tree each voxel belongs and where the stem of this tree is located. This knowledge was used to analyze the role of incoming and outgoing crowns. The contribution of the border effects to the biomass estimation uncertainty was quantified for the case of small-footprint lidar (a simulated canopy height model, CHM) and large-footprint lidar (simulated waveforms with footprint sizes of 23 and 65 m, corresponding to the GEDI and ICESat GLAS sensors). A strong effect of spatial scale was found: e.g., for 20-m plots, on average, 16% of the CHM surface belonged to trees located outside of the plots, while for 100-m plots this incoming CHM fraction was only 3%. The border effects accounted for 40% of the biomass estimation uncertainty at the 20-m scale, but had no contribution at the 100-m scale. For GEDI- and GLAS-based biomass estimates, the contributions of border effects were 23% and 6%, respectively. This study presents a novel approach for disentangling the sources of uncertainty in the remote sensing of forest structures using virtual canopy modeling.

DIVERSITY OF BUTTERFLIES (LEPIDOPTERA) IN MOUNT BROMO FOREST AREA WITH SPECIAL PURPOSE (FASP), KARANGANYAR, CENTRAL JAWA

Butterflies are insects that must be preserved because of their role in balancing ecosystems. The purpose of this study is to know the diversity of butterflies in Mount Bromo FSAP. This research was conducted in May-August 2019. The observation site consisted of four stations, i.e. heterogeneous forest, cultivation field, sonokeling forest, and pine forest. Observation in each station was replicated three times. Time research was applied by making a 200m x 100m plot area in each station. Abiotic factors including humidity, temperature, light intensity, and wind speed were also measured in each station. Several ecological indices of butterflies were determined, including Shannon-Wiener Diversity Index (H'), Evenness Index (E), and Dominance Index (C). They were analyzed descriptively and associated with the nectar plants and abiotic factors. The result showed there are 42 species butterflies belong to five families in Mount Bromo FSAP. The butterfly diversity index is 2.78 or medium category with details 2.38, 2.50, 2.52, and 2.23 for the heterogeneous forest, cultivation field, pine forest, and sonokeling forest respectively. The diversity of butterflies is determined by the number of nectar plant, and abiotic factors suitable for butterfly activity.

Lixo marinho em ambientes costeiros: o caso da Praia Grande no município de São Francisco do Sul/SC

O lixo marinho é uma realidade diagnosticada em diversos estudos ao longo do mundo que apontam impactos nos organismos marinhos, nos processos ecológicos, na paisagem, no turismo e na economia local. O presente estudo tem como objetivo a caracterização desta realidade para o litoral norte catarinense, na Praia Grande, município de São Francisco do Sul/SC. A metodologia de aquisição de lixo marinho em 5 parcelas de 100 m no ambiente praial propiciou a coleta de um total de 137,13 kg de lixo marinho. O plástico foi o material com maior expressividade, com 79,19%, seguido dos seguintes materiais: borracha (6,79%), vidros (6,67%), couro (4,16%), tecido (2,04%). Os demais tipos de materiais possuem baixa representatividade, com peso total inferior a 1%. A pesquisa indicou que na área de estudo podem ocorrer acumulações de lixo marinho na ordem de mais de 7.130 kg em um ano.

Comparison of non-destructive LAI determination methods and optimization of sampling schemes in an open Populus euphratica ecosystem

Populus euphratica (P. euphratica) grows in the water-limited Tarim River Basin in spatially heterogeneous open ecosystems; thus, efforts to quantify the leaf area index (LAI) with optical instruments developed for homogeneous closed canopies have a high probability of failure. In this study, we explored methods for designing an acceptable sampling scheme to quantify the tree LAI for open P. euphratica canopies in arid areas. Field data were collected from three 30m×30m plots and one 100m×100m plot. We compared three indirect methods, i.e. i) allometry, ii) LAI-2000 canopy analyser, iii) Tracing Radiation and Architecture of Canopies (TRAC), and a new semi-direct method combining leaf density and crown volume (SDDV) method for quantifying the isolated tree and canopy LAI of a P. euphratica forest. We also analysed the effects of random and grid sampling designs on the accuracy of the LAI estimates obtained with the LAI-2000. The results showed that the allometric method is applicable to isolated trees with regular shapes; however, because the LAI of P. euphratica was calculated from an allometric equation based on the basal area (at 1.3m), the allometric equation is prone to failure if the basal area is beyond a specific range. Because there are no significant differences in the plot size between the allometric and the SDDV method predictions, the proposed SDDV method can be used as an alternative for field measurements. The combination of LAI-2000 and TRAC is found to be more reliable than TRAC only, and the field view of the LAI-2000 sensor and the clumping index are important factors for sparse vegetation LAI retrieval. The results from sampling optimization showed that for the LAI-2000 instrument, the best sampling method is grid sampling, and the sampling interval should not be less than 20m. For random sampling scheme, the number of sampling points in a 100m×100m plot should be greater than 86 with a coefficients of variation of 15% and an allowable error (AE) of 0.15m2m−2, respectively.

Pollen-mediated gene flow in the cultivation of transgenic cotton under experimental field conditions in Spain

In line with current regulations and in order to ensure the feasible coexistence of genetically modified (GM) cotton (Gossypium hirsutum L.) cultivars with conventional cultivars, it is essential to assess the potential for pollen-mediated gene flow (PMGF). Experiments measuring gene flow in cotton were carried out in two locations in the province of Seville, in southern Spain’s region of Andalusia, first in Peñaflor in 2007 and then in Lebrija in 2009 and again in 2010. In 2009 and 2010, the experiment consisted of a 4ha square field of non-GM cotton, in the middle of which a 40×40m central plot of GM cotton was sown. The GM cotton used as pollen source was glyphosate-tolerant cotton and a non-GM counterpart was used as pollen receptor. In 2007, the non-GM field was a 4.8ha rectangle (120×400m) in the middle of which a 20×100m plot was sown with the GM insect-protected Bt Cotton, which displayed tolerance to the herbicide glufosinate due to the presence of the selectable marker gene. Recipient and donor cultivars went into bloom in synchrony and uniformly. The progeny of non-GM plants grown at distances of from 1m to 50m along eight directions radiating from the central GM plot (up to 150m in some directions) was screened for herbicide resistance to measure PMGF frequency. In the Lebrija experiments, putative hybrids recorded after glyphosate screening were confirmed as true hybrids by Polymerase Chain Reaction (PCR), while glufosinate was used for herbicide screening and Enzyme-Linked ImmunoSorbent Assay (ELISA) was used to confirm resistance of the Peñaflor hybrids. In all cases, PMGF declined exponentially as distance from the pollen source increased. Outcrossing differed among locations, with highest values obtained in 2007 in Peñaflor, where the average across the eight directions was 3% (0.9–9.8%) at 1m from the GM source, and with values of 0.2% (0–0.5%) and 0.06% (0–0.3%), at 10m and 25m respectively. In Lebrija, these values, averaged across directions and years, were 0.17% (0–0.64) at 1m, 0.19% (0–0.98) at 10m and 0.01% (0–0.16) at 25m. Although experimental design, cultivars, insect vectors and environmental conditions could be sources of variation, under the circumstances of this assay, PMGF values at 10m distance were always below the 0.9% threshold based on seeds permissible under European Union (EU) regulation.

Effects of habitat loss on taxonomic and phylogenetic diversity of understory Rubiaceae in Atlantic forest landscapes

Habitat loss has been long recognized as a major driver of the current species extinction crisis, but to date few studies have estimated deforestation thresholds above which biodiversity negatively respond to the changes in landscape configuration. In this study, we used a very representative understory plant family (Rubiaceae) to evaluate the effects of forest cover reduction in the landscape on taxonomic and phylogenetic alpha and beta diversity, species originality, and composition. We selected nine Atlantic forest sites in southern Bahia, Brazil, immersed in landscapes ranging from 9% to 71% of remaining forest cover. We established a 50×100m plot in each site and identified all the Rubiaceae individuals. Forest cover reduction at the landscape scale is strongly and negatively related to the number of individuals, species, and genera of Rubiaceae. Our model predicts that every 10% decreasing in landscape forest cover results in the loss of about three species and 74 individuals of understory Rubiaceae. Canopy openness at the plot level increased linearly with the decrease of forest cover in the landscape. A trend of linear decrease of the phylogenetic diversity with the loss of forest cover was also observed, increasing the co-occurrence of close relatives in more deforested landscapes. Furthermore, we found a reduction in the presence of species with higher values of originality along the gradient of forest cover, as a consequence of species richness reduction. Regardless of the geographical distances, areas with similar values of forest cover were different in composition (β-diversity) and phylogenetic relationship (phylogenetic β-diversity), indicating that even highly deforested landscapes contribute to the regional diversity. We concluded that less forested areas are losing species richness and diversity, and as a consequence species originality, and presenting a general trend of phylogenetic impoverishment at the landscape scale. However, regional conservation initiatives should take all landscapes into account, because they all contribute to taxonomic and phylogenetic beta diversity, to ensure the long-term protection of the irreplaceable evolutionary history of Rubiaceae and the numerous organisms it supports.

Succession and environmental variation influence soil exploration potential by fine roots and mycorrhizal fungi in an Atlantic ecosystem in southern Brazil

Abstract:Fast-growing plant species are plentiful at the early stages of succession and possess roots with greater capacity for soil exploration than slow-growing plant species of late stages. Thus, the dynamics of fine-root production, morphological traits and arbuscular mycorrhizal fungal (AMF) infection intensity were assessed monthly over 1 y in the grassland, scrub, secondary and mature forests of the Atlantic Forest ecosystem, amounting to 13 consecutive samplings. Fine roots were sampled in three 100 × 100-m plots at each study site. Each plot was subdivided in five 20 × 100-m subplots and 15 soil samples were randomly taken from a depth of 0–5 cm in soil within each plot. The average of the fine-root dry mass increased from 1.39 mg cm−3 soil in the grassland to 3.37 mg cm−3 in the secondary forest; fine-root tip diameter varied from 146 μm in the grassland to 303 μm in the mature forest; tissue density from 0.24 g cm−3 root in the grassland to 0.30 g cm−3 in the mature forest and fine-root length was 4.52 cm cm−3 soil in the grassland and 6.48 cm cm−3 soil in the secondary forest. On the other hand, fine-root specific length decreased from 43.9 m g−1 root to 18.3 m g−1 root in the mature forest; incidence of root hairs was 67% in the grassland and 30% in the mature forest; the length of root hairs was 215 μm in the grassland and 112 μm in the mature forest; and the intensity of AMF infection decreased from 66% in the grassland to 17% in the mature forest. In addition to AMF infection, the environmental variation also affected dry mass production and morphological traits of fine roots. During the cool season, fine-root dry mass, fine-root length, incidence and length of root hairs and intensity of AMF infection decreased compared with the warm season. We verified that the potential for soil exploration, that expresses the capacity for nutrient acquisition via fine roots and AMF infection intensity, decreased during the cool season and with the advance of the successional groups. These results indicate that fine-root traits and intensity of AMF infection are influenced by the intrinsic nutrient requirements of the plant species in each ecological group.

Damage patterns after Hurricane Dean in the southern Yucatán: Has human activity resulted in more resilient forests?

We investigated how patterns of hurricane damage were related to windspeed, stand characteristics, and land use in a region where forest composition and structure have been strongly influenced by human activities. In 2007 Hurricane Dean hit the biological corridor between the two largest biosphere reserves on the Yucatán Peninsula as a category 5 hurricane. Land use in the corridor has altered both landscape and forest stand structure. Compared to the upland protected areas, forests in the study area were significantly shorter and characterized by smaller stems. Nine months after the hurricane we assessed the damage in a set of 91 plots to test the effect of local stand structure on hurricane resistance. For each 5×100m plot, we calculated the proportion of both stems and basal area damaged using 7 classes (no damage, small branch, major branch, stem bent, stem snapped, tree uprooted and tree death). Interviews with land- owners provided recent land use histories for the past 30years for most study plots. For the two dominant forest types analysis of variance found that canopy height, median dbh and basal area all varied significantly with land use history and forest type. We tested the effect of median stem diameter, canopy height, stem density, basal area and tree species density on damage. Despite the strength of the storm, on average 27% of stems at the stand level showed no signs of damage and only 5% across the study were killed by the hurricane. In step-wise linear regression models, 13–52% of the variation in damage frequency was accounted for by windspeed and stand structure. Canopy height, basal area and median dbh were significant predictors. For moderate to severe damage classes, measures of stand size were generally positively correlated with damage frequency suggesting that stands with higher canopies and/or greater basal area or median dbh suffered the most during this storm event.

Spatial Variability of Particle Sizes of Coastal Plain Sands Soils of Southeastern Nigeria

Geostatistical analysis facilitates site-specific farming, soil and sanitary landfill management, sustainability and health. The objectives of this study were to assess the extent of variability, spatial dependence and structure of soil particle sizes, pedological and management implications in the coastal plain sands soils of southeastern Nigeria. Surface (0 – 15cm) and subsurface (15 – 30cm) soil samples were collected at 10m2 intervals (rigid grid nodes) in a 100m by 100m plot at the one year fallowed portion of Teaching and Research / Commercial Farm of University of Uyo, in Use Offot, Uyo, Nigeria. A total of 100 samples were collected for each depth. Coefficient of variation (CV) of silt: clay ratio (SCR), silt, fine and coarse sand (surface) were highly variable at both soil depths, while coarse sand of subsurface soil was least variable (13.8%). Spatial dependence of the variables ranged from strong to moderate. The moderately spatially dependent variables included fine sand (36.7%), coarse sand (48.7%) on the surface, and SCR (33.7%) on the subsurface, while the remaining variables were strongly spatially dependent. Pearson correlation coefficients between the semivariances of the two depths showed significance in 52.8% of the entire relationships compared to 19.4% observed on the measured values of the particle sizes. Stronger spatially dependent variables correlated with more variables compared to the moderately spatially dependent variables. It was observed that most of the kriged maps produced displayed similarity in the sedimentation or depositional characteristics which now followed the depositional effect of the massive erosive forces. Kriging may combine correlation and spatial dependence to facilitate site specific farming, soil and sanitary landfills management, knowledge of pedogenesis and sustainability in the coastal plain sands soils.Keywords: coastal plain sands, spatial structure, soil variability, particle sizes, pedogenesis

Seasonal changes in the spatial structures of N2O, CO2, and CH4 fluxes from Acacia mangium plantation soils in Indonesia

Abstract We evaluated the spatial structures of nitrous oxide (N2O), carbon dioxide (CO2), and methane (CH4) fluxes in an Acacia mangium plantation stand in Sumatra, Indonesia, in drier (August) and wetter (March) seasons. A 60 × 100-m plot was established in an A. mangium plantation that included different topographical elements of the upper plateau, lower plateau, upper slope and foot slope. The plot was divided into 10 × 10-m grids and gas fluxes and soil properties were measured at 77 grid points at 10-m intervals within the plot. Spatial structures of the gas fluxes and soil properties were identified using geostatistical analyses. Averaged N2O and CO2 fluxes in the wetter season (1.85 mg N m−2 d−1 and 4.29 g C m−2 d−1, respectively) were significantly higher than those in the drier season (0.55 mg N m−2 d−1 and 2.73 g C m−2 d−1, respectively) and averaged CH4 uptake rates in the drier season (−0.62 mg C m−2 d−1) were higher than those in the wetter season (−0.24 mg C m−2 d−1). These values of N2O fluxes in A. mangium soils were higher than those reported for natural forest soils in Sumatra, while CO2 and CH4 fluxes were in the range of fluxes reported for natural forest soils. Seasonal differences in these gas fluxes appears to be controlled by soil water content and substrate availability due to differing precipitation and mineralization of litter between seasons. N2O fluxes had strong spatial dependence with a range of about 18 m in both the drier and wetter seasons. Topography was associated with the N2O fluxes in the wetter season with higher and lower fluxes on the foot slope and on the upper plateau, respectively, via controlling the anaerobic-aerobic conditions in the soils. In the drier season, however, we could not find obvious topographic influences on the spatial patterns of N2O fluxes and they may have depended on litter amount distribution. CO2 fluxes had no spatial dependence in both seasons, but the topographic influence was significant in the drier season with lowest fluxes on the foot slope, while there was no significant difference between topographic positions in the wetter season. The distributions of litter amount and soil organic matter were possibly associated with CO2 fluxes through their effects on microbial activities and fine root distribution in this A. mangium plantation.

Performance of a Metarhizium anisopliae-treated semiochemical-baited trap in reducing Amblyomma variegatum populations in the field

Experiments were carried out to evaluate the efficacy of Metarhizium anisopliae (Metsch.) Sorok. (Ascomycota: Hypocreales)-treated semiochemical-baited traps for control of Amblyomma variegatum Fabriscius (Acari: Ixodidae) under field conditions. Unfed A. variegatum adults (118) were seeded in each 100-m plot and allowed to acclimatise for 3 days. On the fourth day (Day 4), an emulsifiable formulation of M. anisopliae (consisting of 49.5% sterile distilled water, fungal conidia, 49.5% corn oil and 1% Tween 80) titrated at 10 9 conidia ml −1 was applied in semiochemical-baited traps (900 cm 2) which were placed at five spots within the plot. The control and fungal treatments were repeated after 14 and 28 days soon after rotating the traps clockwise (45°) in order to cover different sections of the plot. In the control plots, emulsifiable formulation without fungus was applied in the semiochemical-baited traps. Six weeks after the initiation of the experiments, five semiochemical-baited traps (untreated) were deployed in each plot for 3 successive days to trap ticks in the treated and control plots. The percentage of ticks recovered in the fungus-treated plots were significantly lower (31.1 ± 5.2%) than in the control plots (85.6 ± 3%) ( P < 0.001), which represented a relative tick reduction of 63.7%. Mortality of 93.8 ± 2.3% was observed among the ticks that were recovered from the field and maintained in the laboratory for 2 weeks; while only 3.3 ± 0.9% died from the control plots. The results of this study open up the possibility of developing an environmentally friendly and low cost application strategy to control Amblyomma ticks.

Spatial pattern and heterogeneity of soil organic carbon and nitrogen in sand dunes related to vegetation change and geomorphic position in Horqin Sandy Land, Northern China

To assesses the effect of geomorphology, topography, and vegetation changes on spatial pattern of soil organic carbon (C) and total nitrogen (N) in sand dunes, we used the quantitative methods to examine the spatial heterogeneity of vegetation cover, soil organic C, and total N in an 11-year naturally restored mobile dune (RMD11) and a 20-year naturally restored mobile dune (RMD20) that had been fenced to exclude grazing in Horqin Sandy Land, northern China. Our results showed that the vegetation cover, plant density, species number and diversity, soil organic C, and total N increased from RMD11 to RMD20 and increased from the 50 x 50-m plot (crest) to the 100 x 100-m plot (slope) in each dune. Geostatistical analysis showed that the spatial structural variance accounted for the largest proportion of the total sample variance in vegetation cover, soil organic C, and total N in each dune plot. Calculated spatial autocorrelation ranges of vegetation cover, soil organic C, and total N increased from RMD11 to RMD20, indicating that longer time since vegetation restoration results in a more homogeneous distribution of vegetation cover, soil organic C, and total N in sand dunes. In addition, the spatial continuity of vegetation cover, soil organic C, and total N decreased from the 50 x 50-m plot (crest) to the 100 x 100-m plot (slope) in each dune. These results suggest that the spatial distribution of soil organic C and total N in sand dunes is associated closely with geomorphic position related to the dune crest and slope, relative elevation of sampling site, and vegetation cover. Understanding the principles of this relationship between them may guide strategies for the conservation and management of semiarid dune ecosystems.

Spatial structures of N 2O, CO 2, and CH 4 fluxes from Acacia mangium plantation soils during a relatively dry season in Indonesia

We investigated spatial structures of N 2O, CO 2, and CH 4 fluxes during a relatively dry season in an Acacia mangium plantation stand in Sumatra, Indonesia. The fluxes and soil properties were measured at 1-m intervals in a 1 × 30-m plot (62 grid points) and at 10-m intervals in a 40 × 100-m plot (55 grid points) at different topographical positions of the upper plateau, slope, and valley bottom in the plantation. Spatial structures of each gas flux and soil property were identified using geostatistical analysis. The means (±SD) of N 2O, CO 2, and CH 4 fluxes in the 10-m grids were 0.54 (±0.33) mg N m −2 d −1, 2.81 (±0.71) g C m −2 d −1, and −0.84 (±0.33) mg C m −2 d −1, respectively. This suggests that A. mangium soils function as a larger source of N 2O than natural forest soils in the adjacent province on Sumatra during the relatively dry season, while CO 2 and CH 4 emissions from the A. mangium soils were less than or consistent with those in the natural forest soils. Multiple spatial dependence of N 2O fluxes within 3.2 m (1-m grids) and 35.0 m (10-m grids), and CO 2 fluxes within 1.8 m (1-m grids) and over 65 m (10-m grids) was detected. From the relationship among N 2O and CO 2 gas fluxes, soil properties, and topographic elements, we suggest that the multiple spatial structures of N 2O and CO 2 fluxes are mainly associated with soil resources such as readily mineralizable carbon and nitrogen in a relatively dry season. The soil resource distributions were probably controlled by the meso- and microtopography. Meanwhile, CH 4 fluxes were spatially independent in the A. mangium soils, and the water-filled pore space appeared to mainly control the spatial distribution of these fluxes.

A nested-intensity design for surveying plant diversity

Managers of natural landscapes need cost-efficient, accurate, and precise systems to inventory plant diversity. We investigated a nested-intensity sampling design to assess local and landscape-scale heterogeneity of plant species richness in aspen stands in southern Colorado, USA. The nested-intensity 2 design used three vegetation sampling techniques: the Modified-Whittaker, a 1000-m multiple-scale plot 2 2 (n 5 8); a 100-m multiple-scale Intensive plot (n 5 15); and a 100-m single-scale Extensive plot (n 5 2 28). The large Modified-Whittaker plot (1000 m ) recorded greater species richness per plot than the 2 other two sampling techniques (P , 0.001), estimated cover of a greater number of species in 1-m 2 subplots (P , 0.018), and captured 32 species missed by the smaller, more numerous 100-m plots of the other designs. The Intensive plots extended the environmental gradient sampled, capturing 17 species missed by the other techniques, and improved species-area calculations. The greater number of Extensive plots further expanded the gradient sampled, and captured 18 additional species. The multi- scale Modified-Whittaker and Intensive designs allowed quantification of the slopes of species-area curves in the single-scale Extensive plots. Multiple linear regressions were able to predict the slope of 2 species-area curves (adj R 5 0.64, P , 0.001) at each Extensive plot, allowing comparison of species richness at each sample location. Comparison of species-accumulation curves generated with each technique suggested that small, single-scale plot techniques might be very misleading because they underestimate species richness by missing locally rare species at every site. A combination of large and small multi-scale and single-scale plots greatly improves our understanding of native and exotic plant diversity patterns.

Análise fitossociológica de algumas áreas remanescentes da floresta do Alto Uruguai, entre os rios Ijuí e Turvo, no Rio Grande do Sul.

Para descrever a composição florística e estrutural de algumas áreas remanescentes da floresta do Alto Uruguai foram levantadas oito unidades amostrais de 15 x 100 m entre os rios Ijuí e Turvo, nos municípios de Roque Gonzáles, Porto Lucena, Porto Xavier, Alecrim, Tuparendi, Horizontina, Criciumal e Três Passos, no estado do Rio Grande do Sul. Nas parcelas foram consideradas todas as árvores vivas com circunferência à altura do peito maior ou igual a 30 cm, onde mediram-se a circunferência, altura do fuste e altura total. Foram amostrados 588 indivíduos distribuídos em 26 famílias, 53 gêneros e 66 espécies. As famílias mais importantes foram Leguminosae, Boraginaceae e Sapindaceae, e as espécies mais importantes foram Patagonula americana, Diatenopteryx sorbifolia, Helietta longifoliata, Luehea divaricata, Holocalyx balansae e Chrysophyllum gonocarpum. Os fragmentos florestais analisados demonstraram estar se regenerando de perturbações sofridas o passado.

Composição florística e fitossociologia do componente arbóreo das florestas ciliares da Bacia do Rio Tibagi: 3. Fazenda Bom Sucesso, Município de Sapopema, PR

Foi estudada a composição florística e fitossociologia de lha de floresta ciliar, localizada às margens do rio Tibagi, no município de Sapopema, PR. (24º 01'S e 50º 41'W) e 780m de altitude. Para tanto, foi demarcada uma parcela de 100X100m subdividida em 100 subparcelas contíguas de 10X10m, utilizando como critério de inclusão um DAP mínimo de 5cm. Foram amostrados 1560 indivíduos reunidos em 41 famílias, 82 gêneros e 125 espécies. O índice de diversidade (Shannon-Weaner) foi de H'=4,2. As espécies mais importantes no levantamento foram Anadenanthera colubrina, Casearia sylvestris, Luehea divaricata, Esenbeckia febrífuga e Parapiptadenia rigida. As famílias com maior número de indivíduos amostrados foram Fabaceae (214) e Myrtaceae (209), tendo esta apresentado o maior número de espécies (18).

Cornstalk Borer Control in Nonirrigated Peanuts in Oklahoma, 1982

Abstract Peanuts were planted on Jun 25 with 0.9-m row spacing in light, sandy soil. Insecticide sprays were applied on Aug 13, Sep 10 and 30 using drop pipes from a boom sprayer with 2 flat spray nozzles/row to direct liquid to the soil surface over the pegging zone. Total volume delivered was 30 gpa. One application of the Terraclor &amp; Lorsban granular formulation was made on Sep 10. A randomized complete block design was utilized with treatments replicated 4 times on 2 row x 100-m plots. On each sampling date 20 plants/plot were removed from the soil and roots, pegs, and pods were examined for larvae. Soil around plants was sifted to locate additional larvae or pupae. Plants with 1 or more live larvae or pupae were considered infested.