Long-term functional group recovery of lotic macroinvertebrates from logging disturbance

2010 ◽  
Vol 67 (7) ◽  
pp. 1126-1134 ◽  
Author(s):  
Damon T. Ely ◽  
J. Bruce Wallace

Clear-cut logging rapidly affects stream macroinvertebrates through substantial alteration of terrestrial–aquatic resource linkages; however, lesser known are the long-term influences of forest succession on benthic macroinvertebrate assemblages, which play key roles in stream ecosystem function. We compared secondary production and standing crops of detritus in two mountain headwater streams within Coweeta Hydrologic Laboratory, North Carolina, USA, as part of a long-term, paired-watershed investigation of macroinvertebrate recovery from whole-catchment logging. Mean annual habitat-weighted abundance and biomass in the disturbed stream (catchment entirely logged 26 years prior) did not differ from that of the reference stream, and secondary production was only 0.8 g ash-free dry mass (AFDM)·m–2·year–1 greater in the disturbed stream (disturbed, 10.1; reference, 9.3). Taxonomic composition, shredder–scraper ratios, and North Carolina biotic index scores were more similar between streams than in previous years. However, mean annual standing crops of benthic organic matter (BOM) were much lower in the disturbed stream (167 g AFDM·m–2) than in the reference stream (339 g AFDM·m–2), and the disturbed stream supported greater macroinvertebrate biomass per unit BOM. We suggest that despite similarities in macroinvertebrate structure and function, past logging activity continues to influence consumer–resource relationships in the disturbed stream through enhanced resource quality.

2005 ◽  
Vol 62 (2) ◽  
pp. 301-311 ◽  
Author(s):  
Brent R Johnson ◽  
J Bruce Wallace

The indirect effects that resources can have on higher trophic levels remain poorly understood for detritus-based ecosystems. Our objective was to examine effects of long-term terrestrial litter exclusion on a larval salamander, Eurycea wilderae, in a detritus-based stream. After 4 years of exclusion treatment, we conducted a mark–recapture study and analyzed gut contents of E. wilderae larvae in the litter exclusion reach, a reach downstream of treatment, and in a reference stream. Eurycea wilderae growth rate (per day), density (individuals per square metre), biomass (milligrams ash-free dry mass per square metre), and production (milligrams ash-free dry mass per square metre per year) were all significantly reduced in the litter exclusion reach. Reduced density in the treatment reach was likely due to elevated hatchling drift driven by reduced prey availability. Larvae from the treatment reach had fewer prey items per gut than larvae in the reference stream and their diet consisted of fewer copepods but more midge larvae, nematodes, and terrestrial insects. The reach downstream of treatment was intermediate between reference and litter exclusion reaches for most measured parameters, indicating residual effects of upstream treatment. Our results provide the first comprehensive evidence of bottom-up limitation of a vertebrate predator in a detritus-based ecosystem and further demonstrate the importance of the terrestrial–aquatic linkage.


2009 ◽  
Vol 39 (10) ◽  
pp. 1871-1880 ◽  
Author(s):  
Martin Schmalholz ◽  
Kristoffer Hylander

The recovery process of boreal bryophyte communities after clear-cutting was studied in a chronosequence in south-central Sweden. We hypothesized that high initial grass cover on clearcuts, high litter cover and low light levels during canopy closure, and shortage of coarse woody substrates would constrain recovery in different ways. Instead, both epigeic and epixylic guilds (i.e., species growing on forest floor and deadwood) displayed a gradual increase in similarity over time from the clear-cut phase, perhaps because of the absence of distinct peaks in needle litter and canopy cover. Epixylic species started to recover long before the accumulation of deadwood, indicating that microclimate rather than substrate availability was the most constraining factor during the first 50 years. Since we did not find any other bottlenecks during the succession after clear-cutting, conservation measures aiming at decreasing local extinction rates during clear-cutting may also increase long-term persistence. On the other hand, as the results from the epixylic guild suggest, other factors during the forest succession, such as the development of a suitable microclimate, might be more important for some organisms, thus possibly mitigating such long-term positive effects of adjusted management during the clear-cutting operation.


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Cassandra R. Davis ◽  
Sarah R. Cannon ◽  
Sarah C. Fuller

PurposeThe purpose of this paper is to identify and describe the long-term impacts of hurricanes on schools and discuss approaches to improving recovery efforts.Design/methodology/approachInterviews with 20 school districts in Texas and North Carolina after Hurricanes Harvey (2017) and Matthew (2016). In total, 115 interviews were conducted with teachers, principals, district superintendents and representatives from state education agencies. Interview questions focused on the impact of storms and strategies for recovery.FindingsThe authors uncovered three long-term impacts of hurricanes on schools: (1) constrained instructional time, (2) increased social-emotional needs and (3) the need to support educators.Research limitations/implicationsThis paper focuses on two storms, in two states, in two successive years. Data collection occurred in Texas, one academic year after the storm. As compared to the North Carolina, data collection occurred almost two academic years after the storm.Practical implicationsThis paper illuminates strategies for stakeholders to implement and expedite hurricane recovery through; (1) updating curricula plans, (2) providing long-term counselors and (3) supporting educators in and out of school.Originality/valueTo date, very few studies have explored the ways in which schools face long-term impacts following a disaster. This paper provides insight to the challenges that prolong the impacts of disasters and impede recovery in schools. With hurricanes and related disasters continuing to affect schooling communities, more research is needed to identify the best ways to support schools, months to years after an event.


2021 ◽  
Author(s):  
V.A. Martynenko ◽  
◽  
B.I. Gruzdev

The results of a long-term studu of the flora of technologenichabitats of the taiga zone of the Komi Republic are summarized. An annotated list of vascular plants is presented, including 406 species from 222 genera and 52 families. For each of them, it is indicated that they belong to a life from, an element of the flora and type of area, an ecologicsl group, zonal and ecotopic affinity. Data on the taxonomic composition of vascular plants, the biomorphrological, geographical, and ecological structures of synanthropic flora, the diversity of synanthropic plant communities, and the stages of vegetation restoration in disturbed areas are presented.


PLoS ONE ◽  
2021 ◽  
Vol 16 (7) ◽  
pp. e0253253
Author(s):  
Sung Han Rhew ◽  
Julia Kravchenko ◽  
H. Kim Lyerly

Alzheimer’s disease (AD), non-AD dementia, and Parkinson’s disease (PD) are increasingly common in older adults, yet all risk factors for their onset are not fully understood. Consequently, environmental exposures, including air pollution, have been hypothesized to contribute to the etiology of neurodegeneration. Because persistently elevated rates of AD mortality in the southern Piedmont area of North Carolina (NC) have been documented, we studied mortality and hospital admissions for AD, non-AD dementia, and PD in residential populations aged 65+ with long-term exposures to elevated levels of ambient air particulate matter 2.5 (PM2.5) exceeding the World Health Organization (WHO) air quality standards (≥10μg/m3). Health data were obtained from the State Center for Health Statistics and the Healthcare Cost and Utilization Project. PM2.5 levels were obtained from the MODIS/MISR and SeaWiFS datafiles. Residents in the Study group of elevated air particulate matter (87 zip codes with PM2.5≥10μg/m3) were compared to the residents in the Control group with low levels of air particulate matter (81 zip codes with PM2.5≤7.61μg/m3), and were found to have higher age-adjusted rates of mortality and hospital admissions for AD, non-AD dementia, and PD, including a most pronounced increase in AD mortality (323/100,000 vs. 257/100,000, respectively). After adjustment for multiple co-factors, the risk of death (odds ratio, or OR) from AD in the Study group (OR = 1.35, 95%CI[1.24–1.48]) was significantly higher than ORs of non-AD dementia or PD (OR = 0.97, 95%CI[0.90–1.04] and OR = 1.13, 95%CI[0.92–1.31]). The OR of hospital admissions was significantly increased only for AD as a primary case of hospitalization (OR = 1.54, 95%CI[1.31–1.82]). Conclusion: NC residents aged 65+ with long-term exposures to ambient PM2.5 levels exceeding the WHO standard had significantly increased risks of death and hospital admissions for AD. The effects for non-AD dementia and PD were less pronounced.


Forests ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1181
Author(s):  
Guy R. Larocque ◽  
F. Wayne Bell

Environmental concerns and economic pressures on forest ecosystems have led to the development of sustainable forest management practices. As a consequence, forest managers must evaluate the long-term effects of their management decisions on potential forest successional pathways. As changes in forest ecosystems occur very slowly, simulation models are logical and efficient tools to predict the patterns of forest growth and succession. However, as models are an imperfect representation of reality, it is desirable to evaluate them with historical long-term forest data. Using remeasured tree and stand data from three data sets from two ecoregions in northern Ontario, the succession gap model ZELIG-CFS was evaluated for mixed boreal forests composed of black spruce (Picea mariana [Mill.] B.S.P.), balsam fir (Abies balsamea [L.] Mill.), jack pine (Pinus banksiana L.), white spruce (Picea glauca [Moench] Voss), trembling aspen (Populus tremuloides Michx.), white birch (Betula papyrifera Marsh.), northern white cedar (Thuja occidentalis L.), American larch (Larix laricina [Du Roi] K. Koch), and balsam poplar (Populus balsamefera L.). The comparison of observed and predicted basal areas and stand densities indicated that ZELIG-CFS predicted the dynamics of most species consistently for periods varying between 5 and 57 simulation years. The patterns of forest succession observed in this study support gap phase dynamics at the plot scale and shade-tolerance complementarity hypotheses at the regional scale.


2014 ◽  
Vol 2 (3) ◽  
pp. 33-46
Author(s):  
Zuzanna Bielec-Bąkowska

AbstractThis paper addresses spatial and temporal variability in the occurrence of thunderstorms and related precipitation in southern Poland between 1951 and 2010. The analysis was based on thunderstorm observations and daily precipitation totals (broken down into the few ranges) from 15 meteorological stations. It was found that precipitation accompanied an overwhelming majority of thunderstorms. The most frequent range of thunderstorm precipitation totals was 0.1–10.0 mm which accounted for 60% of all values while precipitation higher than 20.0 mm accounted only for ca. 8%. During the study period, long-term change in the number of days with thunderstorm precipitation within a certain range displayed no clear-cut trends. Exceptions included: 1) an increase in the number of days with thunderstorm precipitation in the lowest range of totals (0.1–10.0 mm) at Katowice, Tarnów, Rzeszów and Lesko and decrease at Mt. Kasprowy Wierch, 2) an increase in the range 10.1–20.0 mm at Zakopane and 20.1–30.0 mm at Opole, 3) a decrease of the top range (more than 30.0 mm) at Mt. Śnieżka. It was found that the heaviest thunderstorm precipitation events, i.e. totalling more than 30 mm, and those events that covered all or most of the study area, occurred at the time of air advection from the southern or eastern sectors and a passage of atmospheric fronts.


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