scholarly journals Outsized effect of predation: Wolves alter wetland creation and recolonization by killing ecosystem engineers

2020 ◽  
Vol 6 (46) ◽  
pp. eabc5439
Author(s):  
Thomas D. Gable ◽  
Sean M. Johnson-Bice ◽  
Austin T. Homkes ◽  
Steve K. Windels ◽  
Joseph K. Bump

Gray wolves are a premier example of how predators can transform ecosystems through trophic cascades. However, whether wolves change ecosystems as drastically as previously suggested has been increasingly questioned. We demonstrate how wolves alter wetland creation and recolonization by killing dispersing beavers. Beavers are ecosystem engineers that generate most wetland creation throughout boreal ecosystems. By studying beaver pond creation and recolonization patterns coupled with wolf predation on beavers, we determined that 84% of newly created and recolonized beaver ponds remained occupied until the fall, whereas 0% of newly created and recolonized ponds remained active after a wolf killed the dispersing beaver that colonized that pond. By affecting where and when beavers engineer ecosystems, wolves alter all of the ecological processes (e.g., water storage, nutrient cycling, and forest succession) that occur due to beaver-created impoundments. Our study demonstrates how predators have an outsized effect on ecosystems when they kill ecosystem engineers.


2016 ◽  
Author(s):  
Daniel J. Karran ◽  
Cherie J. Westbrook ◽  
Joseph M. Wheaton ◽  
Carol A. Johnston ◽  
Angela Bedard-Haughn

Abstract. Beaver ponds are surface water features that are transient through space and time. Such qualities complicate the inclusion of beaver ponds in local and regional water balances, and in hydrological models, as reliable estimates of surface water storage are difficult to acquire without time and labour intensive topographic surveys. A simpler approach to overcome this challenge is needed, given the abundance of the beaver ponds in North America, Eurasia and southern South America. We investigated whether simple morphometric characteristics derived from readily available aerial imagery or quickly measured field attributes of beaver ponds can be used to approximate surface water storage among the range of environmental settings in which beaver ponds are found. Studied were a total of 40 beaver ponds from four different sites in North and South America. The Simplified V-A-h approach, originally developed for prairie potholes, was tested. With only two measurements of pond depth and corresponding surface area, this method estimated surface water storage in beaver ponds within 5 % on average. Beaver pond morphometry was characterized by a median basin coefficient of 0.91, and dam length and pond surface area were strongly correlated with beaver pond storage capacity, regardless of geographic setting. These attributes provide a means for coarsely estimating surface water storage capacity in beaver ponds. Overall, this research demonstrates that reliable estimates of surface water storage in beaver ponds only requires simple measurements derived from aerial imagery and/or brief visits to the field. Future research efforts should be directed at incorporating these simple methods into both broader beaver-related tools and catchment scale hydrological models.



2017 ◽  
Vol 21 (2) ◽  
pp. 1039-1050 ◽  
Author(s):  
Daniel J. Karran ◽  
Cherie J. Westbrook ◽  
Joseph M. Wheaton ◽  
Carol A. Johnston ◽  
Angela Bedard-Haughn

Abstract. Beaver ponds are surface-water features that are transient through space and time. Such qualities complicate the inclusion of beaver ponds in local and regional water balances, and in hydrological models, as reliable estimates of surface-water storage are difficult to acquire without time- and labour-intensive topographic surveys. A simpler approach to overcome this challenge is needed, given the abundance of the beaver ponds in North America, Eurasia, and southern South America. We investigated whether simple morphometric characteristics derived from readily available aerial imagery or quickly measured field attributes of beaver ponds can be used to approximate surface-water storage among the range of environmental settings in which beaver ponds are found. Studied were a total of 40 beaver ponds from four different sites in North and South America. The simplified volume–area–depth (V–A–h) approach, originally developed for prairie potholes, was tested. With only two measurements of pond depth and corresponding surface area, this method estimated surface-water storage in beaver ponds within 5 % on average. Beaver pond morphometry was characterized by a median basin coefficient of 0.91, and dam length and pond surface area were strongly correlated with beaver pond storage capacity, regardless of geographic setting. These attributes provide a means for coarsely estimating surface-water storage capacity in beaver ponds. Overall, this research demonstrates that reliable estimates of surface-water storage in beaver ponds only requires simple measurements derived from aerial imagery and/or brief visits to the field. Future research efforts should be directed at incorporating these simple methods into both broader beaver-related tools and catchment-scale hydrological models.



2014 ◽  
Vol 3 (1) ◽  
pp. 13-17
Author(s):  
Rachel Anne Kaminsky ◽  
Sara Sirois ◽  
Robert Merritt ◽  
Laura Katz

Beaver ponds act as mercury sinks, exhibiting favorable conditions for the production of neurotoxic methylmercury by sulfate reducing bacteria (SRBs), a group of bacteria that are characterized by function (sulfate reduction) rather than phylogeny.  This study was conducted to explore the diversity of SRB communities inhabiting microenvironments at the sediment-water interface in one beaver pond located on the Avery Brook stream system in the Conway State Forest.  Clone libraries were constructed in order to capture some of the diversity of sulfate-reducing bacteria as well as a biogeographic pattern.  Though the clone libraries did not reveal a biogeographic pattern, the results showed an unprecedented amount of SRB diversity in all sampled microenvironments.



FLORESTA ◽  
2015 ◽  
Vol 45 (3) ◽  
pp. 497
Author(s):  
Silvana Manfredi ◽  
Juliano Pereira Gomes ◽  
Paula Iaschitzki Ferreira ◽  
Roseli Lopes da Costa Bortoluzzi ◽  
Adelar Mantovani

A busca do conhecimento sobre a expansão das florestas em relação aos ecossistemas associados (campestre e banhado) aborda a presença de fatores ambientais como o fogo e o pastejo, frequentemente descritos como determinantes dos processos ecológicos favoráveis à dinâmica sucessional. Dessa forma, objetivou-se verificar se existem diferenças na composição florística do interior de fragmentos florestais e entre setores de transição floresta-campo e floresta-banhado, bem como identificar espécies indicadoras para cada um desses ambientes. O estudo foi realizado em fragmentos florestais situados nos municípios de Bom Jardim da Serra e Lages (Coxilha Rica), onde foram instaladas duas parcelas permanentes de 50x50 m, subdivididas em setores de 10x10 m, categorizados em três setores: Floresta Ombrófila Mista, transição floresta x campo e transição floresta x banhado. Há dissimilaridade florística entre os fragmentos florestais dos locais e, também, entre os setores de transição (ecótonos). As espécies indicadoras dos ecótonos estão vinculadas ao estágio inicial da sucessão florestal, apresentando potencial para colonização do campo, podendo atuar no início do processo de expansão da fronteira florestal.AbstractFloristic dissimilarity and indicator species of Araucaria Forest and ecotones. The search for knowledge about the expansion of forests in relation to associated ecosystems (native grassland and wetland) addresses the presence of environmental factors such as fire and grazing, often described as determinants of ecological processes in favor of succession dynamics. The objective here was to verify if there are differences among the floristic composition of the interior of forest fragments and transition sectors of forest-native grassland and forest-wetland, as well as to identify indicator species for each of these environments. The research was conducted in forest fragments located in the municipalities of Bom Jardim da Serra and Lages (Coxilha Rica), SC, where we installed two permanent plots of 50x50 m, subdivided into sectors of 10x10 m categorized into three sectors: Araucaria Forest, forest transition x native grassland and forest x wetland transition. There is floristic dissimilarity between the local forest fragments and also between the transition areas (ecotones). The indicator species of ecotones are linked to early stages of forest succession, with potential for colonization of the field, they can operate in the start of the expansion of the forest boundary process.Keywords: Araucaria Forest; native grassland; wetland; succession.



1995 ◽  
Vol 52 (6) ◽  
pp. 1318-1326 ◽  
Author(s):  
M. S. Songster-Alpin ◽  
R. L. Klotz

Electron transport system (ETS) activity of sediments as an indication of microbial metabolic activity was measured at four beaver pond sites in central New York State. ETS activity, an indication of microbial biomass and respiration, was measured as the reduction of 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyl tetrazolium chloride (INT) to INT-formazan. Since INT can be reduced by both aerobes and anaerobes, the total microbial respiratory activity in the sediments was measured. The ETS activity increased from means of 11.1–65.0 μg O2∙g−1 dry weight∙h−1 at the free-flowing upstream reaches to means of 221.2–262.6 μg O2∙g−1 dry weight∙h−1 within the beaver ponds. ETS activity decreased with increased depth of sediment probably because of the loss of aerobic activity. When ETS activity was expressed on a per unit area basis (grams O2 per square metre per hour), the increase from upstream reaches to the ponds ranged from 13- to 35-fold. This difference increased to 460- to 2180-fold when the activity was expressed per unit length of stream (micrograms O2 per metre per hour). These data showed that beaver ponds greatly increased microbial activity along streams, likely resulting in changes in biogeochemical cycles controlled directly or indirectly by microorganisms.



Elem Sci Anth ◽  
2014 ◽  
Vol 2 ◽  
Author(s):  
Thomas A. Douglas ◽  
Miriam C. Jones ◽  
Christopher A. Hiemstra ◽  
Jeffrey R. Arnold

Abstract Boreal ecosystems store large quantities of carbon but are increasingly vulnerable to carbon loss due to disturbance and climate warming. The boreal region in Alaska and Canada, largely underlain by discontinuous permafrost, presents a challenging landscape for itemizing carbon sources and sinks in soil and vegetation. The roles of fire, forest succession, and the presence (or absence) of permafrost on carbon cycle, vegetation, and hydrologic processes have been the focus of multidisciplinary research in boreal ecosystems for the past 20 years. However, projections of a warming future climate, an increase in fire severity and extent, and the potential degradation of permafrost could lead to major landscape and carbon cycle changes over the next 20 to 50 years. To assist land managers in interior Alaska in adapting and managing for potential changes in the carbon cycle we developed this review paper by incorporating an overview of the climate, ecosystem processes, vegetation, and soil regimes. Our objective is to provide a synthesis of the most current carbon storage estimates and measurements to guide policy and land management decisions on how to best manage carbon sources and sinks. We surveyed estimates of aboveground and belowground carbon stocks for interior Alaska boreal ecosystems and summarized methane and carbon dioxide fluxes. These data have been converted into similar units to facilitate comparison across ecosystem compartments. We identify potential changes in the carbon cycle with climate change and human disturbance. A novel research question is how compounding disturbances affect carbon sources and sinks associated with boreal ecosystem processes. Finally, we provide recommendations to address the challenges facing land managers in efforts to manage carbon cycle processes. The results of this study can be used for carbon cycle management in other locations within the boreal biome which encompasses a broad distribution from 45° to 83° north.



2021 ◽  
Author(s):  
Thomas A. Douglas ◽  
Christopher A. Hiemstra ◽  
Miriam C. Jones ◽  
Jeffrey R. Arnold

Boreal ecosystems store large quantities of carbon but are increasingly vulnerable to carbon loss due to disturbance and climate warming. The boreal region in Alaska and Canada, largely underlain by discontinuous permafrost, presents a challenging landscape for itemizing carbon sources and sinks in soil and vegetation. The roles of fire, forest succession, and the presence/absence of permafrost on carbon cycle, vegetation, and hydrologic processes have been the focus of multidisciplinary research in boreal ecosystems for the past 20 years. However, projections of a warming future climate, an increase in fire severity and extent, and the potential degradation of permafrost could lead to major landscape and carbon cycle changes over the next 20 to 50 years. To assist land managers in interior Alaska in adapting and managing for potential changes in the carbon cycle, this paper was developed incorporating an overview of the climate, ecosystem processes, vegetation, and soil regimes. The objective is to provide a synthesis of the most current carbon storage estimates and measurements to guide policy and land management decisions on how to best manage carbon sources and sinks. We provide recommendations to address the challenges facing land managers in efforts to manage carbon cycle processes. The results of this study can be used for carbon cycle management in other locations within the boreal biome which encompasses a broad distribution from 45° to 83° north.



1992 ◽  
Vol 49 (4) ◽  
pp. 783-789 ◽  
Author(s):  
Thomas E. Nickelson ◽  
Jeffrey D. Rodgers ◽  
Steven L. Johnson ◽  
Mario F. Solazzi

Habitat use by juvenile coho salmon (Oncorhynchus kisutch) during spring, summer, and winter was examined in Oregon coastal streams. Coho salmon fry were most abundant in backwater pools during spring. During summer, juvenile coho salmon were more abundant in pools of all types than they were in glides or riffles. During winter, juvenile coho salmon were most abundant in alcoves and beaver ponds. Because of the apparent strong preference for alcove and beaver pond habitat during winter and the rarity of that habitat in coastal streams, we concluded that if spawning escapement is adequate, the production of wild coho salmon smolts in most coho salmon spawning streams on the Oregon Coast is probably limited by the availability of adequate winter habitat.



Author(s):  
Carol A. Johnston


2021 ◽  
Vol 4 ◽  
Author(s):  
Marcus Vinícius C. Schmidt ◽  
Yakuna Ullillo Ikpeng ◽  
Tariaiup Kayabi ◽  
Rosely Alvim Sanches ◽  
Katia Yukari Ono ◽  
...  

The indigenous systems of agricultural and forest management in the Amazon are characterized by a deep knowledge of ecological processes, biodiversity, and the use and management of fire. The influence of these systems on the distribution of biodiversity includes semi-domesticated and domesticated species and landscapes, which have led to extensive anthropogenic or cultural forests. However, in many places, the livelihoods of indigenous peoples are being transformed by the intensification of agriculture and social, ecological, and economic changes, putting at risk the sustainability of production systems and food security and sovereignty of these peoples. In the last years, in the Xingu Indigenous Territory (XIT), the food production systems and the form of occupation of territories have changed, affecting the recovery of secondary forests, which now demand a too long period. The increase in the number and frequency of fires has aggravated this situation, due to a drier climate that has become predominant in the region. Changes in climate are attributed to deforestation in the neighboring municipalities, especially in the headwaters of the Xingu river basin. This study was conducted among the Kawaiwete (Tupi-Guarani) and the Ikpeng (Carib-Arara) peoples in the XIT, in the state of Mato Grosso, Brazil. The main objective was to develop alternative techniques of forest management based on indigenous and scientific knowledge more adapted to the new livelihood contexts, aiming to favor forest regeneration in areas dominated by shifting cultivation. We sought to answer the following questions: (I) How do forests regenerate during the fallow period? (II) How can local management improve forest regeneration? (III) Are there indicator species for secondary succession, soil recovery, and vulnerability to fires? (IV) Is the increase in the number of fires affecting the sustainability of the shifting cultivation systems? Our results show that some local practices based on indigenous knowledge have the potential to facilitate natural regeneration, such as choosing forest areas that have been recovered for agricultural use, limiting the number of cultivation cycles, protecting and selecting of individual trees during cultivation period, and attracting seed dispersers. Assisted natural regeneration strategies grounded on indigenous knowledge are promising ways to restore degraded lands of the XIT.



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