Upland Plots Research Articles

Bat Assemblages Are Shaped by Land Cover Types and Forest Age: A Case Study from Eastern Ukraine

Eastern European broadleaved forests north of the 50th degree of latitude serve as a core breeding area for most migratory bat species wintering in Eastern and Central Europe. The southern border of this region has faced an increase in clear-cutting intensity in recent decades. We conducted a standardized mist-netting survey on eleven heterogeneous oak forest plots in order to assess how land cover types and forest age affect abundance, diversity and the breeding of bats. We found that abundance indices and species richness increased from upland plots surrounded by agricultural lands to riverine or waterside plots with high forest cover. Particularly large mature forests older than 90 years positively affected the breeding activity of bats, their abundance indices and overall species richness. Regarding species associations with specific habitats, we found that Myotis brandtii, Nyctalus leisleri and Pipistrellus pygmaeus were mainly found in mature deciduous forest stands, while Plecotus auritus appeared to be the only species tolerating clearcuts and young stands. Forest-dwelling species such as Nyctalus noctula and Pipistrellus nathusii were additionally associated with water habitats. Thus, the combination of mature forests and water sources is essential in shaping Eastern European assemblages of forest bat species.

Effects of agricultural management regimes on rotating cropland ecosystem respiration and its components in Southeast China

Investigating ecosystem, soil and aboveground respiration under different agricultural management regimes (i.e., fertilization, crop types and plowing practices) is critical for better understanding the processes of agricultural carbon cycles. The effects of agricultural management regimes on ecosystem respiration and its soil and aboveground respiration components have not been well identified. We performed a field experiment to measure ecosystem and soil respiration under different management regimes. Air temperature, soil temperature, soil moisture, crop growth characteristics [aboveground biomass (AB), leaf biomass (LB), leaf area index (LAI), specific leaf area (SLA), plant height (PH)] and crop productivity indexes [i.e., yield and biomass of a thousand seeds (BTS)] were also measured. The WrP4 treatment, where nitrogen was applied as chemical fertilizer and straw, had significantly (P < 0.05) higher seasonal cumulative ecosystem respiration (SCER) than the treatments where only chemical nitrogen was applied. Rice paddies had significantly (P < 0.05) lower SCER and seasonal cumulative soil respiration (SCSR) than upland plots during the 2003 summer growing season. No-till treatment significantly (P < 0.05) increased the SCER compared with plowing treatment. Plowing practices had different effects on the SCSR in the different growing seasons. The highest annual ecosystem respiration during the 2002‒2003 and 2003‒2004 rotation years was higher than that in previous studies that used the eddy covariance (EC) technique in croplands. The percentage of soil to ecosystem respiration varied from 31% to 81% across treatments. The SCER across treatments during the winter wheat growing seasons was significantly (P < 0.05) correlated with temperature, maximum aboveground biomass (MAB), maximum leaf biomass (MLB), maximum specific leaf area (MSLA) and BTS. Seasonal variations in ecosystem and soil respiration could be modelled by temperature, moisture, AB, LAI and PH. Moreover, the aboveground respiration coefficient decreased with increasing LAI and PH in the winter wheat, maize and rice plots.

Effects of short‐interval disturbances continue to accumulate, overwhelming variability in local resilience

AbstractIncreasing rates of short‐interval disturbances have the potential to rapidly transform ecosystems via shifts in post‐disturbance regeneration. While research has explored compound events in multiple biomes, we know little regarding how local site conditions interact with short‐interval disturbances to influence post‐disturbance regeneration. Furthermore, questions remain regarding the consequences of continued high frequency events: What happens when emerging new communities are themselves subject to short‐interval disturbances? To investigate effects of ongoing short‐interval fires on regeneration, we examined post‐fire forest regeneration in two locations in interior Alaska. We established 50 plots across a mosaic of fire histories (one, two, or three fires in &lt;70 yr) in an upland and lowland site in interior Alaska. To investigate how shifts in community driven by short‐interval fires differ according to local site conditions, we quantified abundance, proportion, and density of conifer and deciduous regeneration in a drier upland site and a wetter lowland site. Both sites were dominated by black spruce prior to burning. In the drier upland site, black spruce (Picea mariana) presence declined sharply after two fires, while paper birch (Betula neoalaskana) became increasingly abundant with each additional fire. In the wetter lowland site, less organic soil was consumed by fire and presence of black spruce persisted through an initial single reburn (two fires), indicating local topography may temporarily buffer reburning impacts. However, after three burns, conifers were effectively eliminated in both upland and lowland stands. Deciduous regeneration differed with site: Birch dominated in upland plots, while willow (Salix spp.) and aspen (Populus tremuloides) dominated in lowlands. These results offer strong empirical evidence of the divergence of boreal successional trajectories from previous historic norms. Furthermore, results from this study demonstrate shifts in post‐fire succession in forested ecosystems continue to accumulate with additional short‐interval disturbance events, overwhelming the interactive effects of local site conditions.

Subsidence of rice paddy and upland crop fields in Shinotsu Peatland, Hokkaido, Japan

Abstract. Agricultural land use on peatlands inevitably causes ongoing land surface subsidence resulting in a reduction of productivity. In addition, oxidation of the peat substrate associated with subsidence is responsible for greenhouse gas emission with the ensuing consequence for global climatic stability. A concept of “paludiculture”, the utilisation of wet or rewetted peatlands for agriculture, has been proposed in European countries to avoid further subsidence and greenhouse gas emission. However, few studies have documented a long-term record of subsidence through agriculture in wet peatlands such as paddy fields for rice cultivation. In this study, we measured the subsidence rates of peatland in rice paddy use and compared them to the rates in peatland with upland crop cultivation. The average subsidence between 2006 and 2016 for the paddy plots was 3.6±1.9 cm (± SE) and significantly less than that of 25.6±1.7 cm for the upland plots, and the subsidence reduced linearly as the period of paddy use increased. These results suggest that paddy use of peatlands can effectively reduce subsidence. Our results will encourage the use of peatlands with a wet environment as one of the valid options for future peatland management in terms of mitigation of land subsidence and peat loss.

Riparian and adjacent upland forests burned synchronously during dry years in eastern Oregon (1650–1900 CE), USA

Riparian forests link terrestrial and freshwater communities and therefore understanding the landscape context of fire regimes in these forests is critical to fully understanding the landscape ecology. However, few direct studies of fire regimes exist for riparian forests, especially in the landscape context of adjacent upland forests or studies of long-term climate drivers of riparian forest fires. We reconstructed a low-severity fire history from tree rings in 38 1-ha riparian plots and combined them with existing fire histories from 104 adjacent upland plots to yield 2633 fire scars sampled on 454 trees. Historically (1650–1900), low-severity fires burned more frequently in upland than in riparian plots, but this difference was not significant (P=0.15). During more than half of the fire years at both sites, fires were extensive and burned synchronously in riparian and upland plots, and climate was significantly dry during these years. However, climate was not significantly dry when fires burned in only one plot type. Historically, entire riparian zones likely burned in these two study sites of the Blue Mountains during dry years. This study suggests that riparian and upland forests could be managed similarly, especially given the projected increases to fire frequency and intensity from impending climate change.

Mowing Effects on Woody Stem Density and Woody and Herbaceous Vegetation Heights Along Mississippi Highway Right-of-Ways

Abstract Roadside right-of-ways (ROWs) undergo regular disturbances such as mowing, maintenance, wrecks, and road developments, which affect soils, groundwater, surface hydrology, and the composition of vegetation. Roadsides can provide and support an environment for diverse plant communities, but management practices have reduced native grasses, wildflowers, and woody plants. Woody plants are not desirable for traffic safety, maintenance, and visibility along road ROWs. Therefore, the objectives of this study were to investigate effects of roadside mowing frequency on native and nonnative herbaceous and woody plant vertical height coverage and native and nonnative woody stem density within plant communities along highway ROWs. We subdivided 10 research plots, systematically situated along Highway 25 in Oktibbeha and Winston counties, Mississippi, to receive 1) four or more mowings annually, 2) one mowing during fall, and 3) one mowing during fall with supplemental native wildflower seeding. We differentiated upland plots on the basis of soil drainage in upward hills. Riparian (lowland) areas were influenced by overbank inundations from streams and drainages, and were typically spanned by bridges or box culverts. We used line transects to sample vegetation. We detected 277 plant species, including native and nonnative forbs, legumes, grasses, rushes, sedges, and woody perennials (vines, shrubs, and trees). Nonnative grasses exhibited the greatest percent coverage (&amp;gt;90%) in all treatments. Woody plants, including vines, trees, and shrubs, comprised &amp;lt;8% coverage throughout the study. Percent coverage of all vegetation in different height categories differed between upland and riparian elevations (F1,59 &amp;gt; 4.65, P ≤ 0.04), seasons (F1,59 &amp;gt; 12.78, P ≤ 0.01), and between years (F1,59 &amp;gt; 4.91, P ≤ 0.03), but did not differ in height categories among treatments. Of the &amp;lt;8% coverage of woody plants, woody vines comprised most (&amp;gt;68%) of the stem counts, whereas 24% were trees and &amp;lt;8% were shrubs. Woody stem density did not differ among treatments or seasons, but between elevations (F1,59 = 3.34, P = 0.07) and during the 2-y study (F1,59 = 3.21, P = 0.08) as the trend was in the predicted direction (α = 0.05). Thickets of woody vines and low-lying trees and shrubs along the roadside ROWs did not compromise height requirements needed for roadside visibility and safety. At least one mowing per year would be needed to control tree and shrub species for visibility along roadside ROWs. We concluded that a 2-y mowing regimen was no different from mowing once annually and/or more than three times annually in the plant communities in east-central Mississippi. However, one mowing/y retained agronomic plant coverage, which is useful for erosion control and soil stabilization during roadside maintenance. Proactive management implementations can include native plantings, selective herbicide use to decrease nonnatives, continual mowing from roadside edge to 10 m, and only one mowing in late fall with an extension of the boundary to reach beyond 10 m from the roadside edge to suppress invasion of woody plants. Adopting this less-frequent mowing regimen could reduce long-term maintenance costs for Mississippi highways.

Short-term Change in Forest Metrics at Grand Portage National Monument, Minnesota

Forest health monitoring programs can provide routine feedback of key indices and periodic updates of ecosystem health. A forest monitoring program was initiated at Grand Portage National Monument in 2007 with plots resampled in 2014. Grand Portage National Monument is within the southern boreal forest and the suitable habitat for most of its common overstorey species is expected to shift northward and out of the park as climate change progresses. We assessed short-term change in forest health on 20 plots by specifically evaluating change in overstorey density and basal area, forest community composition, and White-tailed deer (Odocoileus virginianus) browsing impacts on the herbaceous layer. Pooled across all overstorey species, both density and basal area increased between sampling events, but neither differed among habitats. For individual species of interest, responses were varied, although balsam Fir (Abies balsamea) increased in both density and basal area over the seven years. The frequency of quadrats supporting at least one preferred browse species did not differ between sampling years although this was greater in upland plots (81%) compared with wet mesic sites (66%). The effect of sampling year on species’ richness depended on habitat. In 2007, richness was higher in upland plots, although in 2014, richness was higher in wet mesic plots. Pooled across both sampling years, modified floristic quality index was greater in wet mesic plots. Our work demonstrates the increasing dominance of A. balsamea at Grand Portage National Monument and that notable differences in forest metrics can be observed over relatively short times.

Bumble bee use of post‐fire chaparral in the central Sierra Nevada

ABSTRACTBumble bees (Bombus spp.) are declining across many regions in the Northern Hemisphere, leading to a need for management actions that will protect and enhance their habitats. In the Sierra Nevada of California, USA, montane chaparral is prevalent across the landscape, particularly after forest fires, and may provide important floral resources for pollinators. However post‐fire montane chaparral is often targeted for removal during reforestation efforts, to reduce competition with young trees. In 2015 and 2016, we conducted non‐lethal bumble bee surveys within 2 areas in the Sierra Nevada that burned in forest fires in 2004. Our goals were to describe bumble bee abundance and species richness in a post‐fire landscape, to compare results from chaparral‐dominated upland vegetation with results from interspersed patches of riparian vegetation, and to identify characteristics of individual chaparral stands that might make some stands more valuable to bumble bees than others. We captured 2,494 bumble bees of 12 species, and used Bayesian hierarchical modeling to determine that bumble bee abundance was substantially greater in riparian plots (modeled capture rate = 1.10 ± 0.31 [SD] bees/survey in 2015, and 2.96 ± 0.83 bees/survey in 2016) than in upland plots ( = 0.47 ± 0.07 bees/survey in 2015, and 1.27 ± 0.18 bees/survey in 2016), which comprised a mix of chaparral shrubs and associated herbaceous plants. Modeled species richness was also greater in riparian plots, with an average mean richness of 4.1 ± 1.8 bumble bee species in riparian plots versus 2.3 ± 1.3 species in upland plots across the 2 years of the study. Within upland and riparian areas, plots dominated by herbaceous vegetation had greater abundance and species richness. One chaparral shrub species, bearclover (Chamaebatia foliolosa), was foraged on preferentially over all other shrub species and over all but 1 forb taxon, and was associated with increased occupancy probability in the Vosnesensky bumble bee (Bombus vosnesenskii), the most abundant bumble bee species on our study plots. A complex of closely related herbaceous species in the genus Phacelia, commonly associated with upland chaparral in our study area, was the plant taxon most frequently used by bumble bees, and appeared to be particularly important during mid‐summer after bearclover flowers became scarce. Our findings suggest that post‐fire chaparral communities are generally less intensively used by bumble bees than nearby riparian vegetation but may nevertheless provide important habitat. When chaparral removal is part of post‐fire forest regeneration strategies, bumble bees will likely benefit from retention of a mosaic of upland habitat patches dominated by herbaceous vegetation and, in our study area, bearclover, which may provide foraging resources throughout the life cycle of local bumble bee colonies. Because habitat characteristics affected the occupancy of individual bumble bee species differently, managers should consider foraging preferences of target bumble bee species when making land management decisions. © 2017 The Wildlife Society.

Oil Palm and Rubber Tree Water Use Patterns: Effects of Topography and Flooding.

Oil palm and rubber plantations extend over large areas and encompass heterogeneous site conditions. In periods of high rainfall, plants in valleys and at riparian sites are more prone to flooding than plants at elevated topographic positions. We asked to what extent topographic position and flooding affect oil palm and rubber tree water use patterns and thereby influence spatial and temporal heterogeneity of transpiration. In an undulating terrain in the lowlands of Jambi, Indonesia, plantations of the two species were studied in plot pairs consisting of upland and adjacent valley plots. All upland plots were non-flooded, whereas the corresponding valley plots included non-flooded, long-term flooded, and short-term flooded conditions. Within each plot pair, sap flux densities in palms or trees were monitored simultaneously with thermal dissipation probes. In plot pairs with non-flooded valleys, sap flux densities of oil palms were only slightly different between the topographic positions, whereas sap flux densities of rubber trees were higher in the valley than at the according upland site. In pairs with long-term flooded valleys, sap flux densities in valleys were lower than at upland plots for both species, but the reduction was far less pronounced in oil palms than in rubber trees (-22 and -45% in maximum sap flux density, respectively). At these long-term flooded valley plots palm and tree water use also responded less sensitively to fluctuations in micrometeorological variables than at upland plots. In short-term flooded valley plots, sap flux densities of oil palm were hardly affected by flooding, but sap flux densities of rubber trees were reduced considerably. Topographic position and flooding thus affected water use patterns in both oil palms and rubber trees, but the changes in rubber trees were much more pronounced: compared to non-flooded upland sites, the different flooding conditions at valley sites amplified the observed heterogeneity of plot mean water use by a factor of 2.4 in oil palm and by a factor of 4.2 in rubber plantations. Such strong differences between species as well as the pronounced heterogeneity of water use across space and time may be of relevance for eco-hydrological assessments of tropical plantation landscapes.

Managing Mixed-Grass Prairies for Songbirds Using Variable Cattle Stocking Rates

Most remaining grasslands are used for livestock grazing; stocking rates could be managed to help stop declining songbird populations. We examined the effects of stocking rates on grassland songbirds in northern mixed-grass prairies using a beyond–Before-After-Control-Impact manipulative experiment in Canada’s Grasslands National Park and adjacent community pastures. The study area consisted of nine 300-ha pastures grazed at a range of stocking rates starting in 2008. We conducted songbird surveys at six upland plots in each pasture from 2006–2010 and measured vegetation structure within each plot from 2008–2010 (n = 54). We evaluated the effects of stocking rates on habitat structure and songbird abundance using linear and generalized linear mixed models. Baird’s sparrow (Ammodramus bairdii) relative abundance declined with increasing stocking rates. Chestnut-collared longspur (Calcarius ornatus) relative abundance increased only at higher stocking rates, indicating a possible threshold effect. Savannah sparrow (Passerculus sandwichensis) relative abundance decreased with stocking rates above 0.4 AUM after a year of grazing. Sprague’s pipit (Anthus spragueii) relative abundance declined with grazing, but the effect was weak and only significant in 1 year. Western meadowlark (Sturnella neglecta) abundance was unaffected by grazing. Stocking rates may be used to benefit grassland songbirds and may alter avian communities after as little as 1 month of livestock grazing. Applying a range of stocking rates regionally may provide habitat for many species.

Groundwater availability mediates the ecosystem effects of an invasion of Prosopis pallida.

Groundwater levels in arid environments are dropping worldwide due to human extraction, and precipitation events are predicted to become rarer and more intense in many arid areas with global climate change. These changes will likely alter both primary productivity and plant–soil nutrient cycles. To better understand the nature of such alterations, we examined effects of groundwater availability on plant–soil nitrogen (N) cycling in areas invaded by the N-fixing phreatophyte, Prosopis pallida, on the dry leeward coast of Hawai‘i Island. Our aims were to quantify effects of groundwater availability to P. pallida on rates of litterfall N inputs and accretion in soils and to quantify effects of groundwater availability on N mineralization and leaching rates of inorganic N under natural rainfall conditions and simulated rain events. Stem water δ18O values indicate that P. pallida trees in lowland plots accessed shallow groundwater, while in upland plots they relied solely on rainfall. During drought periods, P. pallida at upland plots experienced water stress, evidenced by lower stem water potentials, higher water-use efficiency, and lower predawn photosynthetic performance than at lowland plots. Prosopis pallida basal area was 5.3 times greater at lowland plots, and these plots exhibited 17 times higher carbon (C), 24 times higher N, and 35 times higher phosphorus (P) additions via litterfall, indicating that productivity of this phreatophyte was decoupled from rainfall where groundwater was present. Total N mass in soils was 4.7 times greater where groundwater was accessible, supporting the case that groundwater access increased N2 fixation at a stand level. In contrast, N mineralization and leaching losses from soils, though substantially greater in lowland relative to upland areas, were strongly controlled by rainfall. Results provide clear examples of how invasive species with particular functional attributes (i.e., N-fixing phreatophytes) exploit otherwise inaccessible resources to dramatically alter the functioning of the systems they invade and how anthropogenic changes to hydrological processes can also alter ecosystem-level impacts of biological invasions. Results also illustrate a mechanism by which regional groundwater drawdown may reduce soil nutrient accretion and availability in arid regions.

Comparison of riparian and upland forest stand structure and fuel loads in beetle infested watersheds, southern Rocky Mountains

Extensive outbreaks of mountain pine beetle (MPB), spruce beetle (SB), and other insects are altering forest stand structure throughout western North America, and thereby contributing to the heterogeneity of fuel distribution. In forested watersheds, conifer-dominated riparian forests frequently occur as narrow linear features in the landscape mosaic and contribute to the spatial complexity of forest stands and fuel complexes. These streamside forests are valued for providing aquatic and terrestrial habitat, serving as sources of instream and floodplain large wood, and maintenance of streamside microclimates and stream water quality. Despite the ecological importance of riparian forests, few data exist on riparian stand attributes and fuel complexes in watersheds affected by recent beetle outbreaks. To address this need, we measured stand characteristics and fuel loads in riparian areas and adjacent uplands. Within beetle-infested watersheds in northern Colorado and southeastern Wyoming, we sampled 30 pairs of riparian and upland plots (0.05ha). Our goal was to identify bark beetle induced differences in forest structure and fuel profiles between riparian and upland stands. Specific objectives were: (1) to quantify and compare riparian and upland forest characteristics, specifically structure, extent of insect-caused canopy mortality and understory regeneration; (2) to characterize and compare riparian and upland fuel profiles. Basal area did not differ significantly for live, dead, or total (live+dead) overstory trees (⩾10cm diameter at breast height (DBH)) between upland and riparian stands, although variability was high between plot types and among plots. Although riparian and upland plots were both dominated by lodgepole pine, Engelmann spruce, and subalpine fir, they differed in relative proportions of lodgepole pine (higher in uplands) and Engelmann spruce (higher in riparian areas). For these two species, bark beetles caused greater than 80% mortality in diameter classes larger than 20cm DBH across all plots. For subalpine fir, which is not directly affected by MBP or SB, live overstory basal area and stem densities were roughly similar in riparian and upland plots. The combination of MPB-and-SB-caused canopy mortality has diminished differences in overstory basal area composition of riparian and upland stands, making them more structurally similar than prior to the beetle outbreaks. Total understory stem densities of poles, saplings and seedlings were largely comparable across plot types. However, understory live subalpine fir densities were significantly higher in both riparian and upland plots compared to lodgepole pine and Engelmann spruce, suggesting that fir will play an increasingly important role in future forest development across the landscape. With the exception of 1-h fuels and herbaceous plant cover (higher in riparian plots), fuel complexes were also similar in riparian and upland plots, with total woody fuel loads of approximately 45Mgha−1. Although current basal area, understory characteristics and surface fuel distribution are largely similar in riparian areas and uplands, fuel distribution and corresponding fire risk will likely change as the SB infestation progresses, stands respond to overstory mortality, and dead trees fall.

Effect of clonal reproduction on genetic structure in Pentaclethra macroloba (Fabaceae: Mimosoideae).

The existence of monodominant forests on well-drained soils in tropical regions has been widely reported. Such forests most likely result from a combination of both ecological and evolutionary factors. Under conditions of high seed and seedling mortality, vegetative reproduction could create a reproductive advantage leading to forest dominance, and profoundly affect the distribution of genetic variation in a clonal species. We investigated these effects in a low diversity forest site in Northeastern Costa Rica dominated by the species Pentaclethra macroloba, which sprouts from the root mass of fallen trees and from snapped trunks. We examined the population structure of juvenile P. macroloba growing in different soil types and across an elevational gradient. Using seven molecular markers, we genotyped 173 juvenile P. macroloba from 18 plots (six plots in seasonally inundated swamps, and 12 plots in upland non-swamp) spanning 50-300m in elevation at La Selva Biological Station and the adjacent Reserva Ecológica Bijagual in Northeastern Costa Rica. We answered two specific questions: (1) How extensive is clonal reproduction? and (2) what is the distribution of genetic diversity and structure? We found that clonal reproduction occurred exclusively within inundated swamp areas. However, there was no significant difference between genetic diversity measures in swamp and non-swamp plots, which were both generally low when compared with other tropical forest species. Genetic structure was significant across all plots (F(ST) = -0.109). However, genetic structure among swamp plots (F(ST) = 0.128) was higher than among non-swamp upland plots (F(ST) = 0.093). Additionally, spatial autocorrelation among individuals within non-swamp upland plots was significant from the 25 to 100m spatial scale, but not within swamp plots. The degree of overall genetic structure we found in P. macroloba is high for a tropical forest tree. The incidence of clonal reproduction is a contributing factor in genetic differentiation, but the high structure among plots without clonal reproduction indicates that other factors contribute as well.

Habitat Selection by Bothrops atrox (Serpentes: Viperidae) in Central Amazonia, Brazil

Tropical rainforests often appear relatively homogeneous on satellite images, but responses to landscape characteristics may be found on finer scales if habitat characteristics are considered as continuous variables. In this study, we used 30 uniformly distributed plots and 16 plots beside streams to evaluate the effects of distance from stream, litter depth, altitude, slope, and tree density on abundance of Amazonian Lancehead Pitviper (Bothrops atrox). We estimated densities and probabilities of detection of snakes in riparian and upland plots in Reserva Ducke, Manaus, Amazonas, Brazil. Apparent density of individuals of B. atrox was about 6.4 times higher near streams, but the number of individuals in the landscape more than 10 m away from streams was about 3.9 times higher than the number of individuals within 10 m of streams. Movement data from two adult B. atrox evaluated by radio telemetry indicate that individuals can disperse out of plots and away from streams over a period of several months. Det...

Understorey plant community dynamics following a large, mixed severity wildfire in aPinus ponderosa–Pseudotsuga menziesiiforest,Colorado,USA

AbstractQuestionHow do understorey plant communities ofPinus ponderosa–Pseudotsuga menziesiiforests respond during the first 5 yrs following wildfire, and do responses vary with fire severity?LocationColoradoFrontRange,USA.MethodsIn 2002, theHaymanFire burned across 55 800 ha ofColoradoFrontRangeP. ponderosa–P. menziesiiforest. Also burned in the fire were 20 upland and five riparian plots within a 400‐ha study area. These plots had been surveyed for understorey plant composition and cover 5–6 yrs prior. We re‐measured all plots annually from 2003 to 2007, 1–5 yrs post‐fire. Changes in the occurrence of common understorey plant species and in metrics of understorey plant richness and cover were analysed with regard to fire severity and time since fire using repeated measuresANOVA. Compositional changes were explored using ordination.ResultsFire severity (defined in terms of overstorey mortality, overstorey canopy consumption, and forest floor consumption) in upland plots was highly variable, with 50%, 30% and 20% of plots burning with low, moderate and high severity, respectively. For all severities, total cover in uplands declined in the first post‐fire year relative to pre‐fire levels, but met or exceeded pre‐fire levels by post‐fire year five. Total richness in uplands, however, did not similarly decline immediately following fire, due largely to a high return rate of pre‐fire species, and exceeded pre‐fire levels for all severities from post‐fire years 3–5 due to new species recruitment. Over 90% of the common upland species either were found in a similar number of plots before and after the fire, regardless of fire severity or time since fire, or were found in more plots following the fire in at least 1 yr and one severity class. Temporal changes in upland composition occurred for all severities but were most pronounced following moderate and severe fire. In contrast, riparian plots largely burned with low severity, and the understorey plant communities within them exhibited little change in richness, cover and composition over the 5 yrs.ConclusionsOur results suggest that theHaymanFire had largely neutral or stimulatory impacts on understorey plant communities following the first five post‐fire years.

Impacts of Pig Manure-Based Liquid Fertilizer Agricultural Application on the Water Quality of Agricultural Catchment

This study was conducted to understand the effect of the livestock liquid fertilizer treatment at field-scale up to catchment-scale on the water quality properties. Cultivated paddy rice and upland plots located in Gyeonggi province, Korea were treated with two different liquid fertilizers, SP (Liquid fertilizer with storage process) and SCB (Liquid fertilizer with slurry composting and bio-filtration process). Plots with no fertilizer (control A) and chemical fertilizer (control B) were also prepared for comparison. Water quantity and quality were monitored at the catchment outlet for assessing the effect on water quality of stream water. As a result, the losses of N and P and the values of EC (Electronic Conductivity) in the surface drainage water from paddy rice plots treated with SP and SCB were higher than those from the control plots (A and B). In addition, the losses of N and P by the runoff water from upland plots with SP and SCB treatment were higher than those from control plots (A and B). The nutrient outflow from paddy rice fields and uplands with application of liquid pig manure was higher than those from the control plots (A and B). Particularly, the outflow from uplands may directly affect the water quality in neighboring streams. This caused the major eutrophication problem in stream water. In conclusion, it is necessary to establish the proper management practices to prevent the nutrient losses from agricultural fields and the pollutants against water environments.

Emissions of carbon dioxide, methane, and nitrous oxide from short- and long-term organic farming Andosols in central Japan

Here we have investigated the emission of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) from long- and short-term organic farming Andosols in Matsumoto city of Nagano, in central Japan. We focus on three upland plots in Matsumoto, distinguished by how long they had each experienced continuous organic farming (OF)—in these three cases, since 1971, 2009, and 2010 (plots hereafter termed M39-OF, M1-OF, and M1F-OF, respectively). Since 2001, in M39-OF, mainly rye (Secale cereale L., as green manure) and soybeans [Glycine max (L.) Merril, as crop] were cultivated, in winter and summer respectively, without tillage, other fertilizers and agro-chemicals. In contrast, from 2001 to 2008 in M1-OF, and from 2001 to 2009 in M1F-OF, these plots underwent conventional farming of some vegetables with tillage, fertilizer and agro-chemicals. Soils sampled from M39-OF and M1-OF in August 2009 were incubated for 4 weeks in darkness at 25°C. During these 4 weeks, M39-OF emitted 8.0 times more CO2 and 274 times more N2O than M1-OF. Less than 2 µg carbon (C) kg–1 dry soil of CH4 was emitted from both soils. From February 2010 until January 2011, CO2, CH4, and N2O emission rates of M39-OF and M1F-OF were measured almost monthly, using a closed-chamber method. Annual CO2, CH4, and N2O emissions were 317, –1.7, and 27 g CO2-C equivalent m–2 in M39-OF, and 138, –0.2, and 21 g CO2-C equivalent m–2 in M1F-OF, respectively. The rye yield in M39-OF was 334 g C m–2. Soybeans in M39-OF and M1F-OF yielded 290 and 286 g C m–2, and withdrew 230 and 224 g C m–2, respectively. Greenhouse gas (GHG) balance was calculated at –52 and 97 g CO2-C equivalent m–2 in M39-OF and M1F-OF, respectively. Negative GHG balance indicated that M39-OF was acting as a GHG sink, with higher CH4 absorption than M1F-OF. Further, this beneficial function for global warming was thought to be based on its cultivation system, which had included green manure application since 2001. The difference in gas exchange between incubation and field experiments was considered a reason for the difference in N2O emission between incubation and field experiments.

가축분뇨 퇴.액비가 시용된 옥수수 밭토양 특성 변화

A wide diversity of liquid fertilizers and composts produced from the livestock manure in Korea is commonly applied to agricultural lands as an alternative of chemical fertilizers. However, their effects on the crop production and environmental impacts are still vague. The current study was conducted to understand the effects of the pig manure-based liquid fertilizer on the growth of Zea mays L. and soil properties. Four different liquid fertilizers were treated to each cultivated upland plot located in Gyeong-gi province, Korea while no fertilizer (control A) and a chemical fertilizer (control B) were treated to separate plots for comparison. The liquid fertilizer treatment did not make a significant difference in the fresh weight of Zea mays L. compared to the controls. This is probably due to the nutrient residues carried over from the last year fertilization. Electric conductivity (EC) and organic matter contents in soils were increased right after the liquid fertilizer treatments compared to the controls. However, soil pH was maintained as the same as the level of control A. A long-term effect of the continuous treatment of the manure based liquid fertilizer will be carried out in the successive study.

Stand structure, fuel loads, and fire behavior in riparian and upland forests, Sierra Nevada Mountains, USA; a comparison of current and reconstructed conditions

Fire plays an important role in shaping many Sierran coniferous forests, but longer fire return intervals and reductions in area burned have altered forest conditions. Productive, mesic riparian forests can accumulate high stem densities and fuel loads, making them susceptible to high-severity fire. Fuels treatments applied to upland forests, however, are often excluded from riparian areas due to concerns about degrading streamside and aquatic habitat and water quality. Objectives of this study were to compare stand structure, fuel loads, and potential fire behavior between adjacent riparian and upland forests under current and reconstructed active-fire regime conditions. Current fuel loads, tree diameters, heights, and height to live crown were measured in 36 paired riparian and upland plots. Historic estimates of these metrics were reconstructed using equations derived from fuel accumulation rates, current tree data, and increment cores. Fire behavior variables were modeled using Forest Vegetation Simulator Fire/Fuels Extension. Riparian forests were significantly more fire prone under current than reconstructed conditions, with greater basal area (BA) (means are 87 vs. 29 m 2/ha), stand density (635 vs. 208 stems/ha), snag volume (37 vs. 2 m 3/ha), duff loads (69 vs. 3 Mg/ha), total fuel loads (93 vs. 28 Mg/ha), canopy bulk density (CBD) (0.12 vs. 0.04 kg/m 3), surface flame length (0.6 vs. 0.4 m), crown flame length (0.9 vs. 0.4 m), probability of torching (0.45 vs. 0.03), predicted mortality (31% vs. 17% BA), and lower torching (20 vs. 176 km/h) and crowning indices (28 vs. 62 km/h). Upland forests were also significantly more fire prone under current than reconstructed conditions, yet changes in fuels and potential fire behavior were not as large. Under current conditions, riparian forests were significantly more fire prone than upland forests, with greater stand density (635 vs. 401 stems/ha), probability of torching (0.45 vs. 0.22), predicted mortality (31% vs. 16% BA), and lower quadratic mean diameter (46 vs. 55 cm), canopy base height (6.7 vs. 9.4 m), and frequency of fire tolerant species (13% vs. 36% BA). Reconstructed riparian and upland forests were not significantly different. Our reconstruction results suggest that historic fuels and forest structure may not have differed significantly between many riparian and upland forests, consistent with earlier research suggesting similar historic fire return intervals. Under current conditions, however, modeled severity is much greater in riparian forests, suggesting forest habitat and ecosystem function may be more severely impacted by wildfire than in upland forests.

Interannual, seasonal, and diel variation in soil respiration relative to ecosystem respiration at a wetland to upland slope at Harvard Forest

Soil carbon dioxide efflux (soil respiration, SR) was measured with eight autochambers at two locations along a wetland to upland slope at Harvard Forest over a 4 year period, 2003–2007. SR was consistently higher in the upland plots than at the wetland margin during the late summer/early fall. Seasonal and diel hystereses with respect to soil temperatures were of sufficient magnitude to prevent quantification of the influence of soil moisture, although apparent short‐term responses of SR to precipitation occurred. Calculations of annual cumulative SR illustrated a decreasing trend in SR over the 5 year period, which were correlated with decreasing springtime mean soil temperatures. Spring soil temperatures decreased despite rising air temperatures over the same period, possibly as an effect of earlier leaf expansion and shading. The synchronous decrease in spring soil temperatures and SR during regional warming of air temperatures may represent a negative feedback on a warming climate by reducing CO2 production from soils. SR reached a maximum later in the year than total ecosystem respiration (ER) measured at a nearby eddy covariance flux tower, and the seasonality of their temperature response patterns were roughly opposite. SR, particularly in the upland, exceeded ER in the late summer/early fall in each year, suggesting that areas of lower efflux such as the wetland may be significant in the flux tower footprint or that long‐term bias in either estimate may create a mismatch. Annual estimates of ER decreased over the same period and were highly correlated with SR.