Reproducibility of vegetation cover estimates in south‐central Alaska forests

Helm, D. J.; Mead, Bert R.

doi:10.1111/j.1654-1103.2004.tb02234.x

Cited by 34 publications

(29 citation statements)

References 8 publications

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“…Plant cover was measured with the step-point intercept method (Helm and Mead 2004). Four transects were randomly placed in each plot parallel to each other and at least 2 m from any fence or other transect line.…”

Section: Plant Cover Measurementsmentioning

confidence: 99%

Fire and plant invasion, but not rodents, alter ant community abundance and diversity in a semi‐arid desert

2018

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Human activities are increasing the size, frequency, and severity of disturbance across earth's ecosystems including deserts. Ants are important drivers of ecosystem function and are good bioindicators of ecosystem sensitivity to disturbance and change. Rodents also play an important role in ecosystem response to disturbance and often compete with ants for resources. The purpose of our study was to test the main and interactive effects of fire, rodent activity, and time on ant forager abundance, species richness, and diversity, as well as changes in ant mound density and disk area in the Great Basin Desert. We experimentally applied burn and rodent exclusion treatments and used pitfall traps to collect ants each month from April through October from 2014 to 2016. Over the three‐year period, burned areas had lower richness and diversity than unburned areas. Rodent exclusion had minimal effects on the ant community, and there was not a significant rodent exclusion interaction with fire. Treatment effects varied by month and year. The western harvester ant, Pogonomyrmex occidentalis, was the most abundant ant species, comprising about 70% of the total ants captured. Shifts in ant diversity following fire were driven by positive responses of harvester ants to burned habitat conditions. In contrast, all other ant species when analyzed together had lower forager abundance in burned plots, which drove lower ant diversity in burned plots. Ant forager abundance, richness, and diversity increased each year of the study in all plots; however, richness and diversity remained lower in burned areas than in unburned areas each year. Structural equation modeling shows that the effects of fire on ant community diversity are partially mediated through the plant community. While rodents affected the plant community, those effects do not seem to transfer over to the ant community. Pogonomyrmex occidentalis mound density was higher in burned areas, but disk area was smaller. Our results suggest that fire has adverse effects on ant community diversity. This could have long‐lasting effects on ecosystem function in the face of a changing fire regime in deserts of North America caused by invasive annual plants.

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Section: Plant Cover Measurementsmentioning

confidence: 99%

Fire and plant invasion, but not rodents, alter ant community abundance and diversity in a semi‐arid desert

2018

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“…In both 2012 and 2013, we visually assessed cover of each species that fell within or over each quadrat. In 2012, cover estimates were made to the nearest 1% for cover values between 1% and 15% and nearest 5% for cover values between 15% and 100% (Helm andMead 2004, Wilson 2011). In 2013, we estimated all cover values to the nearest 1%.…”

Section: Moth and Vegetation Samplingmentioning

confidence: 99%

Plant diversity enhances moth diversity in an intensive forest management experiment

Root

Verschuyl

Stokely

et al. 2017

Ecological Applications

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Intensive forest management (IFM) promises to help satisfy increasing global demand for wood but may come at the cost of local reductions to forest biodiversity. IFM often reduces early seral plant diversity as a result of efforts to eliminate plant competition with crop trees. If diversity is a function of bottom-up drivers, theory predicts that specialists at lower trophic levels (e.g., insect herbivores) should be particularly sensitive to reductions in plant diversity. We conducted a stand-level experiment to test bottom-up controls on moth community structure, as mediated by degrees of forest management intensity. Using a dataset of 12,003 moths representing 316 moth species, moth richness decreased only slightly, if at all, as herbicide intensity increased (P = 0.062); the moderate treatment, which is most commonly applied in the northwestern USA, was estimated to have 4.72 (±2.14 SE, P = 0.039) fewer species than the control. Structural equation modeling revealed strong support for an effect of herbicide on plant abundance, which influenced plant species richness and subsequently moth species richness. Moth species richness was associated with plant species richness and followed a power law function (z = 0.42, P = 0.006), which is surprisingly consistent with a recent large-scale experiment in agricultural systems, and provides support for bottom-up drivers of moth community structure. Moth abundance was not influenced by the direct effects of silvicultural herbicide treatments. Site-level effects and variation in pre-harvest vegetation communities resulted in residual broadleaf and herbaceous vegetation in even the most intensive treatment. Even at low densities, these residual deciduous and herbaceous plants supported higher than expected moth abundance and richness. We conclude that forest management practices that retain early seral vegetation diversity are the most likely to conserve moth communities.

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“…Observers positioned perpendicularly intersecting ruled ropes over the nest, stood outside the 1-m markers of the ropes, and visually estimated the percent cover of each vegetation type, the sum of which could not exceed 100%. Some studies suggest that visual estimation produces unreliable results from observer bias (Luscier et al 2006), however we believe visual estimation yielded a valid index of vegetative cover because we collaboratively developed standardized protocols, trained all observers, and worked in groups of two or more to collect vegetation data (Kercher et al 2003, Helm and Mead 2004, Symstad et al 2008. Furthermore, plots smaller than 1-m radius were successfully used to describe Golden-winged Warbler habitat (Confer et al 2003).…”

Section: Vegetation Samplingmentioning

confidence: 99%

Variables associated with nest survival of Golden-winged Warblers (Vermivora chrysoptera) among vegetation communities commonly used for nesting

Aldinger¹,

Terhune²,

Wood³

et al. 2015

ACE

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ABSTRACT. Among shrubland-and young forest-nesting bird species in North America, Golden-winged Warblers (Vermivora chrysoptera) are one of the most rapidly declining partly because of limited nesting habitat. Creation and management of high quality vegetation communities used for nesting are needed to reduce declines. Thus, we examined whether common characteristics could be managed across much of the Golden-winged Warbler's breeding range to increase daily survival rate (DSR) of nests. We monitored 388 nests on 62 sites throughout Minnesota, Wisconsin, New York, North Carolina, Pennsylvania, Tennessee, and West Virginia. We evaluated competing DSR models in spatial-temporal (dominant vegetation type, population segment, state, and year), intraseasonal (nest stage and time-within-season), and vegetation model suites. The best-supported DSR models among the three model suites suggested potential associations between daily survival rate of nests and state, time-within-season, percent grass and Rubus cover within 1 m of the nest, and distance to later successional forest edge. Overall, grass cover (negative association with DSR above 50%) and Rubus cover (DSR lowest at about 30%) within 1 m of the nest and distance to later successional forest edge (negative association with DSR) may represent common management targets across our states for increasing Golden-winged Warbler DSR, particularly in the Appalachian Mountains population segment. Context-specific adjustments to management strategies, such as in wetlands or areas of overlap with Blue-winged Warblers (Vermivora cyanoptera), may be necessary to increase DSR for Golden-winged Warblers. Variables associées à la survie des nids de Paruline à ailes dorées (Vermivora chrysoptera) parmi les communautés végétales fréquemment utilisées pour nicherRÉSUMÉ. Parmi les espèces d'oiseaux d'Amérique du Nord qui nichent dans les milieux arbustifs et les jeunes forêts, la Paruline à ailes dorées (Vermivora chrysoptera) est l'une de celles dont les populations diminuent le plus rapidement en raison du peu de milieux de nidification. Afin de freiner cette baisse, la création et l'aménagement de communautés végétales de qualité sont nécessaires pour la nidification de l'espèce. Nous avons examiné s'il était possible d'aménager sur la base de caractéristiques communes dans une grande partie de l'aire de reproduction de cette paruline pour augmenter le taux de survie quotidien des nids (TSQ). Nous avons suivi 388 nids dans 62 stations réparties au Minnesota, au Wisconsin, dans l'État de New York, en Caroline du Nord, en Pennsylvanie, au Tennessee et en Virginie occidentale. Nous avons évalué trois séries de modèles de TSQ fondés sur les caractéristiques spatio-temporelles (type de végétation dominante, segment de la population, État et année), intrasaisonnières (stade du nid et moment durant la saison) et végétales. Parmi tous les modèles, les meilleurs montraient une association potentielle du taux de survie quotidien des nids avec l'État, le moment durant la saison, le pourcent...

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Reproducibility of vegetation cover estimates in south‐central Alaska forests

Cited by 34 publications

References 8 publications

Fire and plant invasion, but not rodents, alter ant community abundance and diversity in a semi‐arid desert

Fire and plant invasion, but not rodents, alter ant community abundance and diversity in a semi‐arid desert

Plant diversity enhances moth diversity in an intensive forest management experiment

Variables associated with nest survival of Golden-winged Warblers (Vermivora chrysoptera) among vegetation communities commonly used for nesting

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