Extending community ecology to landscapes

Urban, Dean L.; Goslee, Sarah C.; Pierce, Ken; Lookingbill, Todd R.

doi:10.1080/11956860.2002.11682706

Cited by 97 publications

(83 citation statements)

References 52 publications

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“…v www.esajournals.org larly, by including a geographic distance matrix in the partial Mantel tests, we tested for a correlation between variables after accounting for the potential influence of spatial autocorrelation (Urban et al 2002). We used Euclidian distance matrices for the response variables, the standardized environmental variables, and the GPS coordinates of the plots.…”

Section: Discussionmentioning

confidence: 99%

A foundation tree at the precipice:Tsuga canadensishealth after the arrival ofAdelges tsugaein central New England

et al. 2012

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Abstract. Hemlock (Tsuga canadensis) plays a unique role in Eastern forests, producing distinctive biogeochemical, habitat, and microclimatic conditions and yet has begun a potentially irreversible decline due to the invasive hemlock woolly adelgid (Adelges tsugae; HWA) that causes foliar damage, crown loss, and mortality of host trees. Understanding the regional, landscape, site, and stand factors influencing HWA spread and impact is critical for predicting future landscape dynamics and directing effective management. Using aerial photographs, we documented hemlock distribution throughout central Massachusetts and subsampled 123 stands to examine the spatial pattern of HWA and its impact on tree vigor and mortality since its arrival in 1989. In the study region, over 86,000 ha of hemlock forest were mapped in 5,127 stands. White pine (Pinus strobus), red oak (Quercus rubra), red maple (Acer rubrum), and black birch (Betula lenta) were common overstory associates. Hemlock abundance increased from south to north, commonly on western and northwestern slopes. Average stand size was 55 ha, overstory basal area ranged from 23 to 55 m 2 ha À1 and overstory stem densities averaged 993 ha À1 .By 2004, 40% of sampled stands were infested, but most stands remained in good health overall; only 8 stands contained high HWA densities and only two had lost .50% overstory hemlock. Out of fifteen stand and landscape predictor variables examined, only latitude and winter climate variables were related to HWA density. Cold temperatures appear to be slowing the spread and impact of HWA at its northern extent as HWA infestation intensity and hemlock mortality and vigor were significantly correlated with average minimum winter temperature. Contrary to predictions, there was no regional increase in hemlock harvesting. The results suggest that regional HWA-hemlock dynamics are currently being shaped more by climate than by a combination of landscape and social factors. The persistence and migration of HWA continues to pose a significant threat regionally, especially in the northern portion of the study area, where hemlock dominates many forests.

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Section: Discussionmentioning

confidence: 99%

A foundation tree at the precipice:Tsuga canadensishealth after the arrival ofAdelges tsugaein central New England

et al. 2012

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“…We used partial Mantel tests to examine group membership as predicted by the environmental variables while controlling for spatial autocorrelation (Urban et al 2002). Tests of these forms help answer questions like 'Are species that are in the same groups also found in similar environments?'…”

Section: Methodsmentioning

confidence: 99%

“…This test determines whether the distance between species in ordination space corresponds to the distance between groups, thereby highlighting the among-to within-group contrast. In theory, there is an optimal number of groups that maximizes the correlation between these distances (Urban et al 2002). To estimate this maximum correlation, we iterated over all possible numbers of groups, i.e.…”

Section: Methodsmentioning

confidence: 99%

“…We used methods described by Field et al (1982), Clarke (1993), and Urban et al (2002) to perform a multivariate analysis of the species data. After assembling the database(s), we performed NMDS analysis of the data, which we plotted on top of interpolated and smoothed environmental surfaces.…”

Section: Methodsmentioning

confidence: 99%

“…One of our primary analytical goals was to determine if natural groups existed in the species data. To find these groups, we iteratively conducted a group contrast Mantel test (Urban et al 2002) between the species distance in the sites by species matrix and the group distance generated by hierarchical agglomerative clustering. The correlation pattern between these 2 distances helps uncover the optimal number of groups in the species data.…”

Section: Methodsmentioning

confidence: 99%

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Community structure in pelagic marine mammals at large spatial scales

Schick¹,

Halpin²,

Read³

et al. 2011

Mar. Ecol. Prog. Ser.

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The understanding of a species' niche is fundamental to the concept of ecology, yet relatively little work has been done on niches in pelagic marine mammal communities. Data collection on the distribution and abundance of marine mammals is costly, time consuming and complicated by logistical difficulties. Here we take advantage of a data archive comprising many different datasets on the distribution and abundance of cetaceans from Nova Scotia through the Gulf of Mexico in an effort to uncover community structure at large spatial scales (1000s of km). We constructed a multivariate ordination of the species data, tested for group structure that might exist within the ordination space, and determined how these groups might differ in environmental space. We examined 3 biogeographic regions: the oceanic waters north and south of Cape Hatteras, NC, and the Gulf of Mexico. North of Hatteras, we found 2 main groups split along a temperature and chlorophyll gradient, with most piscivores being found in cooler, more productive waters of the continental shelf, and most teuthivores being found farther offshore in warmer, less productive waters at the shelf break (200 m isobath). South of Hatteras, we found 3 groups, with the largest group being in warmer, lower chlorophyll waters that are closest to shore. In the Gulf of Mexico, we found 7 groups arrayed along a bottom depth gradient. We also tested the effect of taxonomically lumping different beaked whale species on ordination results. Results showed that when beaked whales were identified to the species level, they clustered out into distinct niches that are separate from those of other Odontocete groups. These results add to an increasing understanding of wildlife habitat associations and niche partitionings in the community structure of pelagic species, and provide important baseline information for future population monitoring efforts. KEY WORDS: Cetaceans · Group contrast Mantel test · Nonmetric dimensional scaling · Multivariate ordination · Northwest Atlantic OceanResale or republication not permitted without written consent of the publisher

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