Specific Vegetation Types Research Articles

Variations in Soil Microbial Communities and Residues Along an Altitude Gradient on the Northern Slope of Changbai Mountain, China

Altitudinally-defined climate conditions provide specific vegetation types and soil environments that could influence soil microbial communities, which in turn may affect microbial residues. However, the knowledge is limited in terms of the degree to which microbial communities and residues present and differ along altitude. In this study, we examined the soil microbial communities and residues along the northern slope of Changbai Mountain, China using phospholipid fatty acid (PLFA) and amino sugar analysis, respectively. Soil samples were taken from five different vegetation belts defined by climates. Principal component analysis (PCA) revealed substantial differences in soil microbial community composition among study sites, appeared to be driven primarily by soil pH and C/N ratio on the first principal component (PC1) which accounted for 50.7% of the total sample variance. The alpine tundra was separated from forest sites on the second principal component (PC2) by a signifiscantly higher amount of fungal PLFA (18:2ω6,9). Soil pH and C/N ratio were also correlated with the ratios of Gram-positive to Gram-negative bacteria (Gm+/Gm−), glucosamine to galactosamine (GluN/GalN), and glucosamine to muramic acid (GluN/MurA). Both total PLFAs and amino sugars were positively correlated with soil organic carbon, inorganic nitrogen, available phosphorus and potassium. We concluded that soil pH and C/N ratio were the most important drivers for microbial community structure and amino sugar pattern, while substrate availability was of great importance in determining the concentrations of microbial communities and residues. These findings could be used to facilitate interpretation of soil microbial community and amino sugar data derived from measurements in latitude or managed forests.

Comparison of soil carbon stocks in Scottish soils between 1978 and 2009

SummaryThe change in soil carbon (C) stock over a 19–31‐year period (mean 25 years) has been measured at 179 sites on a 20‐km grid across Scotland. Sampling was by horizon from a profile pit. Although soil bulk density determinations were absent at the first sampling time, we used bulk density values from the second sampling time calibrated against NIR spectra to predict the missing values. There was no detectable change in overall total soil C stock (mean ± standard error, to a depth of 100 cm), which was 266 ± 15 and 270 ± 15 t C ha−1 for the first and second sampling times, respectively, or generally in C stock within specific vegetation or soil types. The exception was for soils under woodland, excluding those on deep peat, which exhibited a significant (P = 0.05) gain of 1.0 t C ha−1 year−1. Soils under woodland (mainly coniferous plantation) also showed a significant (P = 0.04) increase in C content (g kg−1), a significant decrease in bulk density (P = 0.006) and an increase in the thickness of the Litter‐Fermentation‐Humus (LFH) layer (P = 0.06). Recalculating the C stock to a depth of 15 cm showed a significant increase in overall C stock (when deep peat sites were excluded) as well as specifically in moorland and woodland soils, suggesting that had we sampled only to 15 cm, we would have reached a different conclusion. Both improved grassland soils and those initially under arable cultivation showed a significant decrease in C content. However, the mean thickness of Ap horizons increased from 29 to 32 cm, with a concomitant decrease in C content and a slight increase in bulk density; this we ascribe to deeper ploughing between the sample periods. In the context of possible soil C losses, we can be 95% confident that the mean loss does not exceed 0.2% year−1 and 99% confident that it does not exceed 0.4% year−1.

Phytosociological Database of Non-Forest Vegetation in Croatia

Phytosociological investigations based on the Braun-Blanquet approach were begun in Croatia, by Ivo Horvat and Stjepan Horvatic in the first half of the 20th century. They have had many successors, most of whom were active in the period between 1960 and 1990. A considerable amount of data, both from the literature and those newly collected in the field, has been accumulated. Due to the application of this data to scientific purposes, the construction of a phytosociological database has been in progress for more than ten years. TURBOVEG software is used for storage of the data. So far, over 5,700 releves from the territory of Croatia have been collected. Regarding the coverage of specific vegetation types, the best represented are: grassland, marshland, water, halophilous coastal vegetation and the vegetation of trampled habitats. For these vegetation types, almost all available data have been collected. This report describes the available content in the Phytosociological Database of Non-Forest Vegetation in Croatia (GIVD ID EU-HR001).

Factors Affecting Hatch Success of Hawksbill Sea Turtles on Long Island, Antigua, West Indies

Current understanding of the factors influencing hawksbill sea turtle (Eretmochelys imbricata) hatch success is disparate and based on relatively short-term studies or limited sample sizes. Because global populations of hawksbills are heavily depleted, evaluating the parameters that impact hatch success is important to their conservation and recovery. Here, we use data collected by the Jumby Bay Hawksbill Project (JBHP) to investigate hatch success. The JBHP implements saturation tagging protocols to study a hawksbill rookery in Antigua, West Indies. Habitat data, which reflect the varied nesting beaches, are collected at egg deposition, and nest contents are exhumed and categorized post-emergence. We analyzed hatch success using mixed-model analyses with explanatory and predictive datasets. We incorporated a random effect for turtle identity and evaluated environmental, temporal and individual-based reproductive variables. Hatch success averaged 78.6% (SD: 21.2%) during the study period. Highly supported models included multiple covariates, including distance to vegetation, deposition date, individual intra-seasonal nest number, clutch size, organic content, and sand grain size. Nests located in open sand were predicted to produce 10.4 more viable hatchlings per clutch than nests located >1.5 m into vegetation. For an individual first nesting in early July, the fourth nest of the season yielded 13.2 more viable hatchlings than the initial clutch. Generalized beach section and inter-annual variation were also supported in our explanatory dataset, suggesting that gaps remain in our understanding of hatch success. Our findings illustrate that evaluating hatch success is a complex process, involving multiple environmental and individual variables. Although distance to vegetation and hatch success were inversely related, vegetation is an important component of hawksbill nesting habitat, and a more complete assessment of the impacts of specific vegetation types on hatch success and hatchling sex ratios is needed. Future research should explore the roles of sand structure, nest moisture, and local weather conditions.

Global resorption efficiencies and concentrations of carbon and nutrients in leaves of terrestrial plants

Nutrient resorption in plants influences nutrient availability and cycling and is a key process in biogeochemical models. Improved estimates of resorption parameters are needed for predicting long‐term primary productivity and for improving such models. Currently, most models assume a value of 50% resorption for nitrogen (N) and phosphorus (P) and lack resorption data for other nutrients and for specific vegetation types. We provide global estimates of resorption efficiencies and nutrient concentrations for carbon (C), N, and P and the first global‐scale estimates for essential nutrients such as potassium (K), calcium (Ca), and magnesium (Mg). We also examine leaf mass loss during senescence (LML) globally and for different plant types, thus defining a mass loss correction factor (MLCF) needed to quantify unbiased resorption values. We used a global meta‐analysis of 86 studies and ∼1000 data points across climates for green and senesced leaves in six plant types: ferns, forbs, graminoids, conifers, and evergreen and deciduous woody angiosperms. In general, N and P resorption differed significantly from the commonly used global value of 50% (62.1%, 64.9%, respectively; P < 0.05). Ca, C, and Mg showed lower average resorptions of 10.9%, 23.2%, and 28.6%, respectively, while K had the highest resorption, at 70.1%. We also found that resorption of all nutrients except Ca depended on leaf nutrient‐status; globally, C, N, P, K, and Mg showed a decrease in resorption with increased nutrient status. On average, global leaf mass loss was 24.2%. Overall, our resorption data differ substantially from commonly assumed values and should help improve ecological theory and biogeochemical and land‐surface models.

Movement and habitat use of feral swine near domestic swine facilities

AbstractFeral swine (Sus scrofa), a successful invasive species in the United States, have established growing populations in 38 states and are a reservoir of diseases important to domestic swine. An understanding of habitat use and movements is important for the prevention of disease transmission between feral and domestic swine. To assess risk posed to neighboring domestic swine facilities in East and South Texas, we determined habitat use and movement patterns of feral swine within 10 miles of domestic swine facilities, identified similarities in habitat preferences and vegetation types directly surrounding facilities, assessed effects of wet and dry conditions on general habitat use, and determined whether landscape features such as corridors or boundaries influenced movements across utilized habitats. Kernel area values (95% isopleths) for wet and dry periods were different (F2,16 = 6.38, P = 0.005) between East and South Texas. Feral swine preferred habitat characteristics commonly found surrounding domestic swine facilities. Feral swine also demonstrated disproportionate use of specific vegetation types as compared to availability during both wet and dry periods. Additionally, the presence of paved, 2‐lane roads influenced movements of feral swine. The new knowledge of habitat use and landscape movements we present can be used for more efficient application of targeted management and eradication strategies near domestic swine facilities, particularly in emergency situations such as disease outbreaks. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.

植被对多年冻土的影响研究进展

作为冰冻圈的主体,多年冻土是岩石圈与大气圈水热交换的产物,它的存在、分布及水热过程受到多种时空尺度环境因子的控制和影响。植被是生物圈的重要组成部分,是岩石圈与大气圈热量交换的媒介,它的存在和变化影响着多年冻土的水热过程和空间分布。文章综述了近几十年来植被对多年冻土影响的研究。首先,植被参与地气之间的水热周转过程,通过反射太阳辐射、贴地植被的吸水保水作用以及截留积雪作用等,对下伏冻土产生错综复杂的影响。但是不同植被类型的反射太阳辐射能力、保水与截留能力等各不相同,产生的影响大小有别。其次,同一植被类型的不同层次(如乔木层、灌木层等)对多年冻土的影响也不同,其中贴地植被产生的影响最显著。植被截留积雪,使得地面接收的太阳辐射和地表水分重分配复杂化,从而间接地影响多年冻土环境。因此当植被发生扰动后(如森林火灾和砍伐植被),就会对其所处的多年冻土环境产生各种不利影响,引发冻土灾害,甚至导致多年冻土消融。实际上植被与冻土同为寒区自然生态系统和环境的重要组成部分,它们在长期地质和生物演化中形成生态平衡。因此,植被还常常被用于指示多年冻土及其空间分布。最后提出目前研究中存在的问题,并对未来研究方向进行了展望。;As the main body of the earth cryosphere, permafrost is formed as a result of heat-moisture exchanges between the lithosphere and atmosphere. The occurrence, distribution and thermal regime of permafrost are affected by many environmental factors of varied spatiotemporal scales. As the medium, a participant and a buffer layer of heat-moisture exchanges between the lithosphere and atmosphere, vegetation and its changes significantly affect the hydro-thermal regimes and distributive features of permafrost. In this paper, the influences of vegetation on permafrost were systematically reviewed. Vegetation has relatively high albedo and capability for water holding and retention, which vary with different types of vegetation and have great impacts on the heat-moisture regimes of permafrost. In vertical structure, there are distinct layers for a given type of vegetation. Each layer has different influences on the thermal regime of permafrost, especially the ground cover layer. Compared to the area above crown canopy, which usually reflects and absorbs probably 40% of solar radiation, the crown canopy significantly affects net radiation and ground surface temperatures in forest. Vegetation, especially the canopy structure, considerably controls the snow accumulation and redistribution through the interception component of the water budget, wind speed, and solar radiation at the snow surface, resulting in a significant impact on the heat-moisture regimes of permafrost. Therefore, deforestation, such as for farming or fuels, may alter snow accumulation, albedo, surface coverage, and capability of water holding of vegetation. This may greatly modify the permafrost environment, induce many types of permafrost hazards, or even result in the thawing and eventually decaying of permafrost patches. Permafrost and vegetation are key components of ecological system in cold regions. They are interdependent and interactive, and have reached dynamic equilibria in the geological and biological evolutionary processes. In permafrost regions, specific vegetation types or their combinations usually present because of appropriate temperatures and moisture conditions. Therefore, the occurrences of specific plant species or a plant community can largely indicate the occurrence of permafrost. Finally, some problems unresolved in the research at present are identified in this paper, and the prospect for further study is also proposed.

Future Global Soybean Yield Projections

This paper introduces the relationships between climate conditions and global scale soybean yields and their future projections until 2050. Using a combination of historical datasets and climate model projections, yield responses to temperature and precipitation change were discussed together with input of fertilizer. Future climate projection is based on downscale dataset from IPCC, A1 scenario. Datasets used in this study include spatial information but not yield data. To improve the accuracy of estimation, the specific vegetation types were used to obtain climate conditions on crop area. The relationships between soybean yield and climate conditions on crop area were conducted for soybean producing countries and future global soybean yield until 2050 are discussed.

A Summary of Fire Frequency Estimates for California Vegetation before Euro-American Settlement

California fire regimes have been altered from those that occurred prior to Euro-American settlement, and are predicted to continue to change as global climates warm. Inclusion of fire as a landscape-level process is considered essential to successful ecological restoration in many ecosystems, and presettlement fire regimes provide foundational information for restoration or “realignment” of ecosystems as climate change and land use changes progress. The objective of our study was to provide an up-to-date, comprehensive summary of presettlement fire frequency estimates for California ecosystems dominated by woody plants, and to supply the basis for fire return interval departure (FRID) mapping and analysis in California. Using the LANDFIRE Biophysical Settings (BpS) vegetation-fire regime types as a framework, we used literature review and the outcomes of regional expert workshops to develop twenty-eight presettlement fire regime (PFR) groups based on similarity of their relationships with fire. We then conducted an exhaustive review of the published and unpublished literature pertaining to fire return intervals (FRIs) observed prior to significant Euro-American settlement in the twenty-eight PFRs, and summarized the values to provide a single estimate of the mean, median, mean minimum, and mean maximum FRI for each PFR.Much variability was evident among PFRs, with mean FRIs ranging from 11 yr to 610 yr, and median FRIs ranging from 7 yr to 610 yr; mean minimum FRIs ranged from 5 yr to 190 yr, and mean maximum FRIs ranged from 40 yr to 1440 yr. There was also high variability within many PFRs, and differences between minimum and maximum FRIs ranged from 32 yr to 1324 yr. Generally, median FRIs were lowest for productive drier forests such as yellow pine, dry and moist mixed conifer, and oak woodland (7 yr, 9 yr, 12 yr, and 12 yr, respectively). Median FRIs were highest for less productive woodlands such as pinyon-juniper (94 yr), high elevation types such as subalpine forest (132 yr), very dry types such as desert mixed shrub (610 yr), and productive moist forests such as spruce-hemlock (275 yr mean FRI). Our summary of California’s presettlement fire regimes should be a useful reference for scientists and resource managers, whether they are seeking a general estimate of the central tendency and variability of FRIs in a broadly defined vegetation type, background information for a planned restoration project or a mechanistic model of vegetation-fire interactions, or a list of literature pertaining to a specific vegetation type or geographic location.

Vegetation during UMBI and deposition of Tuff IF at Olduvai Gorge, Tanzania (ca. 1.8 Ma) based on phytoliths and plant remains

As part of ongoing research at Olduvai Gorge, Tanzania, to determine the detailed paleoenvironmental setting during Bed I and Bed II times and occupation of the basin by early hominins, we present the results of phytolith analyses of Tuff IF which is the uppermost unit of Bed I. Phytoliths were identified in most of the levels and localities on the eastern paleolake margin, but there are not always sufficient numbers of identifiable morphologies to infer the specific type of vegetation due to dissolution. Some surge surfaces and reworked tuff surfaces were vegetated between successive ash falls, as indicated by root-markings and the presence of a variety of phytolith morphotypes. Dicotyledonous wood/bark types were dominant except at the FLK N site just above Tuff IF when monocots are dominant and for the palm-dominated sample from the reworked channel cutting down into Tuff IF at FLK N. The area between the two fault scarps bounding the HWK Compartment, approximately 1 km wide, was vegetated at various time intervals between some of the surges and during the reworking of the Tuff. By lowermost Bed II times the eastern margin was fully vegetated again. Climate and tectonic activity probably controlled the fluctuating lake levels but locally the paleorelief and drainage were probably the controlling factors for the vegetation changes. These data support a scenario of small groups of hominins making brief visits to the paleolake during uppermost Bed I times, followed by a more desirable vegetative environment during lowermost Bed II times.

Exploring large vegetation databases to detect temporal trends in species occurrences

Question: Can vegetation releve databases be used to analyse species losses and gains in specific vegetation types in Germany over time? Does the type of response (increase or decline in relative frequency) conform to observed large-scale environmental trends in the last decades? Location: Germany. Exploring the German Vegetation Reference Database Halle (GVRD) that was established for forest and grassland vegetation within the framework of German Biodiversity Exploratories. Methods: Use of generalized linear models (GLMs) for testing changes in temporal frequency of plant taxa in a semi-dry grassland data set (Mesobromion) and a beech forest data set (Fagion). Data were either aggregated by year, decade or by a balanced re-sampling approach. Interpretation of the observed changes was based on species traits. Results: In both data sets significant temporal changes were observed, although the frequency of the majority of species remained unchanged. In both data sets, species with a temporal increase in frequency had higher Ellenberg N and F indicator values, compared to species that decreased, thus indicating effects of widespread atmospheric nitrogen deposition. In the forest data set, the observed increase in recruitment of deciduous trees pointed to a change in management, while trends in the grassland data set suggested use abandonment, as seen in an increased frequency of woody species. Conclusion: We demonstrate that vegetation databases represent very valuable resources for analysis of temporal changes in species frequencies. GLMs proved their value in detecting these trends, as also shown by the interpretability of model results with species traits. In contrast, the method of aggregation or re-sampling had little influence on the general outcome of analyses.

Carbon storage in terrestrial ecosystems: do browsing and grazing herbivores matter?

Large mammalian herbivores manifest a strong top-down control on ecosystems that can transform entire landscapes, but their impacts have not been reviewed in the context of terrestrial carbon storage. Here, we evaluate the effects of plant biomass consumption by large mammalian herbivores (>10 kg adult biomass), and the responses of ecosystems to these herbivores, on carbon stocks in temperate and tropical regions, and the Arctic. We calculate the difference in carbon stocks resulting from herbivore exclusion using the results of 108 studies from 52 vegetation types. Our estimates suggest that herbivores can reduce terrestrial above- and below-ground carbon stocks across vegetation types but reductions in carbon stocks may approach zero given sufficient periods of time for systems to respond to herbivory (i.e. decades). We estimate that if all large herbivores were removed from the vegetation types sampled in our review, increases in terrestrial carbon stocks would be up to three orders of magnitude less than many of the natural and human-influenced sources of carbon emissions. However, we lack estimates for the effects of herbivores on below-ground biomass and soil carbon levels in many regions, including those with high herbivore densities, and upwards revisions of our estimates may be necessary. Our results provide a starting point for a discussion on the magnitude of the effects of herbivory on the global carbon cycle, particularly given that large herbivores are common in many ecosystems. We suggest that herbivore removal might represent an important strategy towards increasing terrestrial carbon stocks at local and regional scales within specific vegetation types, since humans influence populations of most large mammals.

Natal Dispersal and Sociality of Young Galapagos Hawks on Santiago Island

The Galapagos Hawk (Buteo galapagoensis) is the only diurnal resident raptor in the Galapagos Archipelago, where it exhibits a cooperatively polyandrous mating system. Before breeding, young hawks spend 3-4 years as non- territorial floaters. Individuals in this age class are highly gregarious on the island of Santiago. Here we examine patterns in natal dispersal and ask whether they appear to develop social affiliations with particular individuals during their juvenile years. Using data collected between 1998 and 2009 from a banded population of 25 territorial groups, we found that natal dispersal is more likely to be to territories adjacent to natal territories than expected by chance, and is not significantly related to the specific type of vegetation of the natal territory. We found no evidence of social affiliations or stable coalitions among particular juveniles; instead they moved in opportunistic aggregations.

Habitat suitability of patch types: A case study of the Yosemite toad

Understanding patch variability is crucial in understanding the spatial population structure of wildlife species, especially for rare or threatened species. We used a well-tested maximum entropy species distribution model (Maxent) to map the Yosemite toad (Anaxyrus (= Bufo) canorus) in the Sierra Nevada mountains of California. Twenty-six environmental variables were included in the model representing climate, topography, land cover type, and disturbance factors (e.g., distances to agricultural lands, fire perimeters, and timber harvest areas) throughout the historic range of the toad. We then took a novel approach to the study of spatially structured populations by applying the species-environmental matching model separately for 49 consistently occupied sites of the Yosemite toad compared to 27 intermittently occupied sites. We found that the distribution of the entire population was highly predictable (AUC = 0.95±0.03 SD), and associated with low slopes, specific vegetation types (wet meadow, alpine-dwarf shrub, montane chaparral, red fir, and subalpine conifer), and warm temperatures. The consistently occupied sites were also associated with these same factors, and they were also highly predictable (AUC = 0.95±0.05 SD). However, the intermittently occupied sites were associated with distance to fire perimeter, a slightly different response to vegetation types, distance to timber harvests, and a much broader set of aspect classes (AUC = 0.90±0.11 SD). We conclude that many studies of species distributions may benefit by modeling spatially structured populations separately. Modeling and monitoring consistently-occupied sites may provide a realistic snapshot of current species-environment relationships, important climatic and topographic patterns associated with species persistence patterns, and an understanding of the plasticity of the species to respond to varying climate regimes across its range. Meanwhile, modeling and monitoring of widely dispersing individuals and intermittently occupied sites may uncover environmental thresholds and human-related threats to population persistence.

Acute toxicity of commonly used forestry herbicide mixtures to Ceriodaphnia dubia and Pimephales promelas

Because many herbicides selectively control specific species or types of vegetation, they are often applied as mixtures to achieve better control over undesirable vegetation. When herbicides are applied in forest ecosystems, streams, ponds, and other bodies of water are typically protected by buffer zones in which no herbicide is applied. However, in some landscapes, small wetlands and streams are difficult to see and avoid, thus the potential acute toxicity of herbicide mixtures to aquatic organisms is of interest, yet it has not been well-studied. We examined the acute toxicity of 23 different herbicide mixtures to Ceriodaphnia dubia and fathead minnows (Pimephales promelas) at environmentally relevant concentrations, and, where possible, characterized mixture interactions using Marking's Additive Index. Maximum exposure concentrations were equivalent to applying the maximum allowable rate for each component directly to the surface of a 6-in. deep pond with no dissipation following application. Under the conditions of this study, herbicide formulations containing Accord Concentrate (glyphosate), Arsenal AC (imazapyr), Chopper (imazapyr), Escort (metsulfuron methyl), Oust XP (sulfometuron methyl), and Velpar L (hexazinone) were not associated with appreciable acute toxicity to fathead minnows or C. dubia when used alone or in mixtures with each other and various surfactants and adjuvants. Herbicide mixtures for which Additive Indexes could be calculated exhibited primarily antagonistic or simple additive toxicity. In the few cases where synergistic toxicity was observed, the degree of synergism was slight, never exceeding approximately twice the effect estimated based on additive toxicity. Based on the results of this study, neither acute toxicity nor enhanced acute aquatic toxicity due to synergistic mixture effects appears to be a significant concern for applications of the herbicide mixtures most commonly used in forestry.

Diversity and ecology of tropical African fungal spores from a 25,000-year palaeoenvironmental record in southeastern Kenya

Fossil fungal spores and other non-pollen palynomorphs (NPPs) are powerful environmental proxies in European palaeoecological and archaeological contexts. However, their application on other continents, and particularly in the tropics, is hampered by uncertain equivalence with morphologically similar taxa in Europe, and incomplete knowledge of their ecology in the new local contexts. Here we use fossil NPP assemblages in a 25,000-year sediment record from Lake Challa, a steep-sided crater lake near Mt. Kilimanjaro in southeastern Kenya, to assess NPP diversity in a tropical-African context and the equivalence of African taxa with their European counterparts. We recovered a total of 65 well-defined NPP types, of which 61 are fungal spores, and 42 could be linked to known taxa. We provide diagnoses and illustrations of 61 recovered taxa, 58 of which have not been documented before. Using the Challa pollen record of past regional vegetation dynamics and two independent proxies of past temperature and rainfall, we also assessed the association of individual fungal taxa with particular species and biomes of tropical-African vegetation, and with the history of regional climate change. We often found strong correspondence between the stratigraphic distribution of individual fungal spore taxa and the occurrence of specific vegetation types. Changing climate conditions appear to have had a strong impact on the ability of fungi to play a role in the decomposition of dead plants. For fungal spore assemblages, the most prominent change in regional palaeoenvironments over the past 25,000 years occurred at the start of the wet early Holocene, following Younger Dryas drought. Epicoccum purpurascens is common in the Glacial and Late-Glacial parts of the sequence, but shows a strong decline during the early Holocene. Coniochaeta cf. ligniaria occurs throughout the record but shows dramatic fluctuations that appear to relate to major changes in humidity. Correlation between fungal abundance and humidity is also observed in taxa for which the Challa region provided suitable habitat from ca. 16,500 cal. yr BP (e.g., Curvularia) or from the Late-Glacial to Holocene transition (e.g., Tetraploa aristata, Dictyoarthrinium cf. sacchari, cf. Byssothecium, types HdV-1032 and HdV-1033, cf. Alternaria, cf. Brachysporium, cf. Helminthosporium, Spegazzinia tessarthra and cf. Lasiodiplodia theobromae). Many of these taxa did not occur, or were rare, during both wet and dry phases of the Glacial period, suggesting an additional temperature effect on their occurrence in tropical African environments. A possibly dominant role of temperature is revealed in the stratigraphic distribution of Acrodictys, which appears at the onset of deglacial climate warming ca. 17,500 cal. yr BP and remains common throughout both wet and dry phases of the Holocene. Spores of the dung-inhabiting fungus Sporormiella occur throughout the 25,000-year record without notable fluctuations, suggesting little changes in the overall population density of large herbivores in the region.

Assessing Performance of Bioretention Boxes in Hot and Semiarid Regions

This paper presents the performance results of bioretention pilot experiments conducted in Bryan, Texas, a hot and semiarid area. Five steel boxes were constructed. Each of four boxes was filled with an underdrain pipe, gravel, pea gravel, and soil–compost media and planted with a specific type of vegetation, including shrubs, grass species specified for highways in Texas, native grasses, and Bermuda grass (Cynodon dactylon). The fifth box, the control, had no vegetation planting but contained the other materials. Performance testing was conducted 14 months after construction. Synthetic runoff that mimicked highway storm water runoff characteristics was placed into the pilot boxes, and the concentrations of various pollutants in influent and effluent samples were measured. The results suggested that the pilot boxes effectively removed zinc, lead, total suspended solids, and ammonia–nitrogen, but exported copper, nitrate–nitrogen (NO3-N), total nitrogen (TN), and total phosphorus. The leaching out of the boxes by pollutants could be attributed to the use of compost incorporated in the soil–compost media. Vegetation plays an important role in NO3-N and TN removals through root uptake and denitrification processes in the root zone. This paper, based on the results of the study, discusses implications for designing bioretention facilities in a hot, semiarid region.

A General Characterization for Polarimetric Scattering From Vegetation Canopies

Current polarimetric model-based decomposition techniques are limited to specific types of vegetation because of their assumptions about the volume scattering component. In this paper, we propose a generalized probability density function based on the nth power of a cosine-squared function. This distribution is completely characterized by two parameters; a mean orientation angle and the power of the cosine-squared function. We show that the underlying randomness of the distribution is only a function of the power of the cosine-squared function. We then derive the average covariance matrix for various different elementary scatterers showing that the result has a very simple analytical form suitable for use in model-based decomposition schemes.

Importance of habitat type classifications for predicting ruffed grouse use of areas for drumming

To incorporate ruffed grouse ( Bonasa umbellus) habitat planning in forest management, it is necessary for managers to understand factors contributing to grouse habitat use. Previous studies examining ruffed grouse drumming habitat documented relationships between drumming grouse and broad vegetation categories (e.g., northern hardwoods, young aspen [P opulus spp.], oak [ Quercus spp.]), but few studies have documented how drumming grouse respond to ecological variations in site conditions of aspen or other vegetation types that might be used. Our objectives were to determine the utility of habitat type classifications in predicting the occurrence of ruffed grouse drumming habitat in the western Upper Peninsula of Michigan, and demonstrate how classifications may be used to understand how forest management may affect ruffed grouse habitat. We used survey routes on state land and conducted drumming surveys during mid-April and early May at 78 points in 2005 and 2006. We recorded the number of drumming males heard at each point, the azimuth to where the grouse was heard, and a qualitative measure of distance to determine in which forest stands grouse were drumming. Using GIS, we determined the specific vegetation type, age class, and habitat type, evaluated habitat suitability, and determined a suitability score for areas in which grouse were drumming. We constructed a logistic regression model that calculated the probability of grouse use of areas for drumming based on vegetation characteristics at used and random locations. Our results indicated that the probability of grouse use of an area for drumming is based on inherent site characteristics (i.e., habitat type) and habitat suitability. The model is useful for planning forest management activities and understanding how grouse may respond to spatial or temporal changes in vegetation through succession or manipulation.

Landholder views on the boundaries of the Macquarie Marshes

The Macquarie Marshes are an extensive wetland system, situated at the lower end of the Macquarie River in central western NSW. The marshes are the focus of considerable debate over management issues. The Macquarie Marshes Catchment Committee is preparing a Land and Water Management Plan to deal with these issues. The necessary first step in this planning process was exploring the concept of a boundary of marshes and defining a boundary of an appropriate planning area, including the marshes. Community views on wetland boundaries were determined from the results of semi-structured interviews and a landholder questionnaire. Following negotiations, particularly with landholders who considered that they did not own marsh country, an acceptable planning area was defined for the purpose of the planning process. With the outer planning area boundary determined, specific management options can then be considered for either the whole are or for components of this study area e.g. for specific vegetation types. Scientific data and the political context were also explored to provide a background to the decision on a planning area. The interaction of factors which led to the decision as well as difficulties in delineating a boundary are discussed.