Limits...
A multi-scale spatial analysis of native and exotic plant species richness within a mixed-disturbance oak savanna landscape.

Schetter TA, Walters TL, Root KV - Environ Manage (2013)

Bottom Line: Exotic richness was better explained at the 120-m extent while native richness was better explained at the 60-m extent.We found that percentage of human-modified land cover (negatively correlated with native richness and positively correlated with exotic richness) was a particularly useful predictor of plant species richness and that human-caused disturbances exert a strong influence on species richness patterns within a mixed-disturbance oak savanna landscape.Our results emphasize the importance of using a multi-scale approach to examine the complex relationships between spatial heterogeneity and plant species richness.

View Article: PubMed Central - PubMed

Affiliation: Metropolitan Park District of the Toledo Area, 5100 West Central Ave., Toledo, OH, 43615, USA. tim.schetter@metroparkstoledo.com

ABSTRACT
Impacts of human land use pose an increasing threat to global biodiversity. Resource managers must respond rapidly to this threat by assessing existing natural areas and prioritizing conservation actions across multiple spatial scales. Plant species richness is a useful measure of biodiversity but typically can only be evaluated on small portions of a given landscape. Modeling relationships between spatial heterogeneity and species richness may allow conservation planners to make predictions of species richness patterns within unsampled areas. We utilized a combination of field data, remotely sensed data, and landscape pattern metrics to develop models of native and exotic plant species richness at two spatial extents (60- and 120-m windows) and at four ecological levels for northwestern Ohio's Oak Openings region. Multiple regression models explained 37-77 % of the variation in plant species richness. These models consistently explained more variation in exotic richness than in native richness. Exotic richness was better explained at the 120-m extent while native richness was better explained at the 60-m extent. Land cover composition of the surrounding landscape was an important component of all models. We found that percentage of human-modified land cover (negatively correlated with native richness and positively correlated with exotic richness) was a particularly useful predictor of plant species richness and that human-caused disturbances exert a strong influence on species richness patterns within a mixed-disturbance oak savanna landscape. Our results emphasize the importance of using a multi-scale approach to examine the complex relationships between spatial heterogeneity and plant species richness.

Show MeSH

Related in: MedlinePlus

Mean plant species richness (per 1,000 m2 plot) among five Oak Openings communities for all, native, and exotic species. Error bars are one standard deviation. Means without shared letters (comparing total, native, and exotic species richness across community type) differ at P < 0.05 (Tukey’s test)
© Copyright Policy - OpenAccess
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3753500&req=5

Fig3: Mean plant species richness (per 1,000 m2 plot) among five Oak Openings communities for all, native, and exotic species. Error bars are one standard deviation. Means without shared letters (comparing total, native, and exotic species richness across community type) differ at P < 0.05 (Tukey’s test)

Mentions: Among five Oak Opening community types, we recorded 406 vascular plant species (349 native, 57 exotic), including 48 species listed as endangered, threatened, or potentially threatened in Ohio (ODNR 2010). This accounted for one-third of the region’s known vascular plant flora (Moseley 1928; Walters 2007) and 34 % of the region’s documented state-listed rare plant species within a sampled area of 3.9 ha (<0.01 % of the Oak Openings region’s total land area). Less than 2 % of specimens observed in the field could not be positively identified to species. Refer to Schetter (2012) for a complete list of recorded species. Total species richness was not significantly different among community types (Fig. 3). Native richness tended to be greatest in mesic prairies while it tended to be lowest in sand barrens. Exotic richness was four to six times greater in dry prairies and sand barrens compared to the other community types. Native richness was positively correlated with exotic richness only among wet prairies (R2 = 0.74, F1,7 = 9.72, P = 0.044, corrected for spatial autocorrelation following Dutilleul (1993)). Among the upland communities and at the three higher levels of the classification hierarchy, there was no statistically significant relationship between native and exotic richness (P < 0.05). Thirty out of 39 research plots occurred within existing managed preserves including all oak savanna, mesic prairie and wet prairie plots; while four of eight dry prairie plots and two of seven sand barrens plots occurred within managed preserves. While the effects of specific management and restoration treatments could not be evaluated from our data, the fact that oak savanna, mesic prairie, and wet prairie sample sites were not found outside of existing managed preserves within our sampling design supports existing evidence that large-scale intact remnants of these communities do not persist in the Oak Openings region without regular ecological management treatments such as prescribed fire (see Schetter and Root 2011).Fig. 3


A multi-scale spatial analysis of native and exotic plant species richness within a mixed-disturbance oak savanna landscape.

Schetter TA, Walters TL, Root KV - Environ Manage (2013)

Mean plant species richness (per 1,000 m2 plot) among five Oak Openings communities for all, native, and exotic species. Error bars are one standard deviation. Means without shared letters (comparing total, native, and exotic species richness across community type) differ at P < 0.05 (Tukey’s test)
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3753500&req=5

Fig3: Mean plant species richness (per 1,000 m2 plot) among five Oak Openings communities for all, native, and exotic species. Error bars are one standard deviation. Means without shared letters (comparing total, native, and exotic species richness across community type) differ at P < 0.05 (Tukey’s test)
Mentions: Among five Oak Opening community types, we recorded 406 vascular plant species (349 native, 57 exotic), including 48 species listed as endangered, threatened, or potentially threatened in Ohio (ODNR 2010). This accounted for one-third of the region’s known vascular plant flora (Moseley 1928; Walters 2007) and 34 % of the region’s documented state-listed rare plant species within a sampled area of 3.9 ha (<0.01 % of the Oak Openings region’s total land area). Less than 2 % of specimens observed in the field could not be positively identified to species. Refer to Schetter (2012) for a complete list of recorded species. Total species richness was not significantly different among community types (Fig. 3). Native richness tended to be greatest in mesic prairies while it tended to be lowest in sand barrens. Exotic richness was four to six times greater in dry prairies and sand barrens compared to the other community types. Native richness was positively correlated with exotic richness only among wet prairies (R2 = 0.74, F1,7 = 9.72, P = 0.044, corrected for spatial autocorrelation following Dutilleul (1993)). Among the upland communities and at the three higher levels of the classification hierarchy, there was no statistically significant relationship between native and exotic richness (P < 0.05). Thirty out of 39 research plots occurred within existing managed preserves including all oak savanna, mesic prairie and wet prairie plots; while four of eight dry prairie plots and two of seven sand barrens plots occurred within managed preserves. While the effects of specific management and restoration treatments could not be evaluated from our data, the fact that oak savanna, mesic prairie, and wet prairie sample sites were not found outside of existing managed preserves within our sampling design supports existing evidence that large-scale intact remnants of these communities do not persist in the Oak Openings region without regular ecological management treatments such as prescribed fire (see Schetter and Root 2011).Fig. 3

Bottom Line: Exotic richness was better explained at the 120-m extent while native richness was better explained at the 60-m extent.We found that percentage of human-modified land cover (negatively correlated with native richness and positively correlated with exotic richness) was a particularly useful predictor of plant species richness and that human-caused disturbances exert a strong influence on species richness patterns within a mixed-disturbance oak savanna landscape.Our results emphasize the importance of using a multi-scale approach to examine the complex relationships between spatial heterogeneity and plant species richness.

View Article: PubMed Central - PubMed

Affiliation: Metropolitan Park District of the Toledo Area, 5100 West Central Ave., Toledo, OH, 43615, USA. tim.schetter@metroparkstoledo.com

ABSTRACT
Impacts of human land use pose an increasing threat to global biodiversity. Resource managers must respond rapidly to this threat by assessing existing natural areas and prioritizing conservation actions across multiple spatial scales. Plant species richness is a useful measure of biodiversity but typically can only be evaluated on small portions of a given landscape. Modeling relationships between spatial heterogeneity and species richness may allow conservation planners to make predictions of species richness patterns within unsampled areas. We utilized a combination of field data, remotely sensed data, and landscape pattern metrics to develop models of native and exotic plant species richness at two spatial extents (60- and 120-m windows) and at four ecological levels for northwestern Ohio's Oak Openings region. Multiple regression models explained 37-77 % of the variation in plant species richness. These models consistently explained more variation in exotic richness than in native richness. Exotic richness was better explained at the 120-m extent while native richness was better explained at the 60-m extent. Land cover composition of the surrounding landscape was an important component of all models. We found that percentage of human-modified land cover (negatively correlated with native richness and positively correlated with exotic richness) was a particularly useful predictor of plant species richness and that human-caused disturbances exert a strong influence on species richness patterns within a mixed-disturbance oak savanna landscape. Our results emphasize the importance of using a multi-scale approach to examine the complex relationships between spatial heterogeneity and plant species richness.

Show MeSH
Related in: MedlinePlus