Testing the Power of a Wetland Vegetation Monitoring Survey Design to Detect Change Based on Visual Cover Estimates

Johns, C.V.; Brownstein, G.; Blick, R. A. J.; Erskine, Peter D.; Fletcher, Andrew

doi:10.1007/s13157-015-0694-7

Cited by 2 publications

(1 citation statement)

References 27 publications

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“…We also generated percent cover estimates for each transect by averaging across all quadrats within a transect. Visual cover estimates, while sometimes not as precise as point counts, are reliable protocols to detect differences in studies such as ours (see discussions in Dethier et al 1993;Johns et al 2015;Nguyen et al 2015). These data are presented cautiously here, as a way to compare relative differences in abundance among taxa and locations.…”

Section: Discussionmentioning

confidence: 82%

Non-native species colonization of highly diverse, wave swept outer coast habitats in Central California

et al. 2018

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More non-native species (NNS) are reported from harbors, estuaries and protected embayments than in wave-exposed, open coast habitats. In California (USA), hundreds of NNS have become established in international ports, and dozens are known from smaller estuaries. In contrast, only 22 NNS are reported from the state's 1350 km of open coast.As a result, the perception that open coast habitats are not vulnerable to invasions has persisted. Management and monitoring focuses on ports and estuaries; the last major monitoring effort on the open coast occurred in 2004. Much of the species-rich Central California coast is now part of a network of marine protected areas (MPAs). We surveyed 12 wave-swept rocky intertidal and eight subtidal sites (from 37°53'40 N 122°42'30 W to 36°31'16 N 121°56'22 W) for NNS. At least one NNS was detected at half of the sites surveyed, but most were not widespread or abundant. One exception, a bryozoan in the Watersipora spp. complex, known primarily from ports and estuaries, was found at multiple sites, and was abundant at some. Another non-native, the alga Caulacanthus ustulatus, was abundant at a single site. MPAs were just as likely as sites outside of MPAs to have NNS. For subtidal sites, proximity to a harbor was correlated with the abundance of non-natives. Our findings suggest that our study area is still relatively uninvaded, but the success of Watersipora within some of these highly diverse rocky shore sites underscores the potential vulnerability of high-value open coast systems to invasions.

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Section: Discussionmentioning

confidence: 82%

Non-native species colonization of highly diverse, wave swept outer coast habitats in Central California

et al. 2018

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Disentangling observer error and climate change effects in long‐term monitoring of alpine plant species composition and cover

Futschik

Winkler

Steinbauer

et al. 2019

J Vegetation Science

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QuestionsLong‐term programs monitoring the impact of climate change on alpine vegetation necessarily involve changing observers. We aim at quantifying observer errors and ask if the signal of alpine vegetation transformation due to climate change exceeds pseudo‐changes caused by observer errors.LocationTwo mountain regions in the Alps, Schrankogel and Hochschwab (both Austria), and one in the High Tatra Mountains (Slovakia).MethodsVascular plant species presence and cover were recorded on 10–12 1‐m2 plots by 13–14 observers per site. Observer errors were calculated as species turnover, and deviations of species cover and the plot thermic vegetation indicator (which is correlated with temperature) from the mean over all observers. Observer errors in estimating species cover were split into a random and systematic part. The influence of plot and species characteristics on observer errors was investigated using (generalized) linear mixed‐effect models. Changes over time from three surveys in species turnover, cover and the thermic vegetation indicator were related to the amount of observer error using a bootstrap approach.ResultsSpecies cover was the most influential factor affecting observer errors in recording species lists and in species cover estimation. Plot attributes and observer identity had a weak but significant influence on errors in the thermic vegetation indicator. Systematic errors in estimating species cover were ≤5%. Changes over time in estimating species cover, as well as in species turnover and the thermic vegetation indicator exceeded observer errors in all cases where the observation period was ≥10 years.ConclusionsThe thermic vegetation indicator, which combines species composition and cover with species’ elevational distributions, provides a reliable estimate of warming‐related vegetation changes. Our results underline the importance of long‐term monitoring and long observation periods, which enable us to account for short‐term fluctuations and observer errors alike.

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Testing the Power of a Wetland Vegetation Monitoring Survey Design to Detect Change Based on Visual Cover Estimates

Cited by 2 publications

References 27 publications

Non-native species colonization of highly diverse, wave swept outer coast habitats in Central California

Non-native species colonization of highly diverse, wave swept outer coast habitats in Central California

Disentangling observer error and climate change effects in long‐term monitoring of alpine plant species composition and cover

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