Soil Enzyme Activity and Soil Nutrients Jointly Influence Post-Fire Habitat Models in Mixed-Conifer Forests of Yosemite National Park, USA

Disentangling the relative importance of habitat filtering and dispersal limitations at local scales (<1 km2) in shaping species composition remains an important question in community ecology. Previous studies have examined the relative importance of these mechanisms using topography and selected soil properties. We examined both topography and edaphic properties from 160 locations in the recently burned 25.6 ha Yosemite Forest Dynamics Plot (YFDP) in Yosemite National Park, California, USA. In addition to eight soil chemical properties, we included phosphatases and urease enzymes in a definition of habitat niches, primarily because of their rapid changes with fire (compared to soil nutrients) and also their role in ecosystem function. We applied environmental variables to the distributions of 11 species. More species–habitat associations were defined by soil properties (54.5%) than topographically-defined habitat (45.4%). We also examined the relative importance of spatial and environmental factors in species assemblage. Proportions explained by spatial and environmental factors differed among species and demographic metrics (stem abundance, basal area increment, mortality, and recruitment). Spatial factors explained more variation than environmental factors in stem abundance, mortality, and recruitment. The contributions of urease and acid phosphatase to habitat definition were significant for species abundance and basal area increment. These results emphasize that a more complete understanding of niche parameters is needed beyond simple topographic factors to explain species habitat preference. The stronger contribution of spatial factors suggests that dispersal limitation and unmeasured environmental variables have high explanatory power for species assemblage in this coniferous forest.

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Structuring of Dragonfly Communities (Insecta: Odonata) in Eastern Amazon: Effects of Environmental and Spatial Factors in Preserved and Altered Streams

Insects ◽

10.3390/insects10100322 ◽

2019 ◽

Vol 10 (10) ◽

pp. 322 ◽

Cited By ~ 2

Author(s):

Oliveira-Junior ◽

Juen

Keyword(s):

Environmental Factors ◽

Biotic Interactions ◽

Environmental Variation ◽

Relative Importance ◽

Spatial Variables ◽

Spatial Factors ◽

The Past ◽

Analytical Perspective ◽

Physical Features ◽

Natural Communities

The evaluation of the effects of environmental factors on natural communities has been one of the principal approaches in ecology; although, over the past decade, increasing importance has been given to spatial factors. In this context, we evaluated the relative importance of environmental and spatial factors for the structuring of the local odonate communities in preserved and altered streams. Adult Odonata were sampled in 98 streams in eastern Amazonia, Brazil. The physical features of each stream were evaluated and spatial variables were generated. Only environmental factors accounted for the variation in the Odonata community. The same pattern was observed in the suborder Zygoptera. For Anisoptera, environmental factors alone affect the variation in the community, considering all the environments together, and the altered areas on their own. As the two Odonata suborders presented distinct responses to environmental factors, this partitioning may contribute to an improvement in the precision of studies in biomonitoring. We thus suggest that studies would have a greater explanatory potential if additional variables are included, related to biotic interactions (e.g., competition). This will require further investigation on a finer scale of environmental variation to determine how the Odonata fauna of Amazonian streams behaves under this analytical perspective.

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Effects of environmental factors and soil properties on soil organic carbon stock in a natural dry tropical area of Cameroon

SOIL ◽

10.5194/soil-7-677-2021 ◽

2021 ◽

Vol 7 (2) ◽

pp. 677-691

Author(s):

Désiré Tsozué ◽

Nérine Mabelle Moudjie Noubissie ◽

Estelle Lionelle Tamto Mamdem ◽

Simon Djakba Basga ◽

Dieudonne Lucien Bitom Oyono

Keyword(s):

Environmental Factors ◽

Organic Carbon ◽

Soil Organic Carbon ◽

Soil Properties ◽

National Park ◽

Carbon Stock ◽

Forest Reserve ◽

Soil Organic Carbon Stock ◽

Tropical Area ◽

Organic Carbon Stock

Abstract. Research carried out on soil organic carbon stock (SOCS) in the Sudano-Sahelian region of Cameroon is very rare. The few existing studies are mostly available in reports and concern in most cases carbon stocks in plant biomass. In order to contribute to the documentation on soils in this part of the country, the present work was designed to evaluate the SOCS in the main soil types and the influence of environmental factors and soil properties on these stocks under the natural dry tropical area of the Sudano-Sahelian zone of Cameroon. The study was undertaken in four sites, including three natural forest reserves (Laf, Zamai, Kosohon) and one national park (Mozogo), located at different latitudes. Three replicates were collected at each site, giving rise to three sampling points chosen per site, from 0 to 75 cm depth, for the determination of SOCS. At each sampling point, soils were sampled using depth increments of 25 cm from the surface. The studied area is covered by Haplic Vertisols, Dystric Arenosols, Dystric Leptosols and Dystric Planosols. Total SOCS (T-SOCS) content, which refers to a depth of 75 cm, decreases with increasing latitude, with 249±26.26 Mg ha−1 in Vertisols at Laf forest reserve most southerly located, 199±8.00 Mg ha−1 in Arenosols at Zamai forest reserve, 166±16.63 Mg ha−1 in Leptosols at Kosohon forest reserve and 161±8.88 Mg ha−1 in Planosols at Mozogo national park most northerly located, regardless of the altitude. No significant correlation was noted between T-SOCS and the altitude. A good correlation was noted between precipitation which decreases with increasing latitude and T-SOCS, indicating the importance of climate in the distribution of T-SOCS in the study area, which directly influences the productivity of the vegetation. More than 60 % of the SOCS was stored below the first 25 cm from the soil surface, a peculiarity of SOCS in drylands. The SOCS in the Sudano-Sahelian area of Cameroon is mainly influenced by climate and vegetation.

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Environmental and spatial factors affect the composition and morphology of tadpole assemblages

Canadian Journal of Zoology ◽

10.1139/cjz-2017-0313 ◽

2018 ◽

Vol 96 (10) ◽

pp. 1130-1136

Author(s):

N.C.S. Marques ◽

F. Nomura

Keyword(s):

Environmental Factors ◽

Morphological Variation ◽

Environmental Conditions ◽

Environmental Variables ◽

Morphological Diversity ◽

Oviposition Site ◽

Spatial Factors ◽

Assemblage Composition ◽

Different Types ◽

Spatial Coordinates

Understanding how community compositions are affected by environmental and spatial factors are essential to provide knowledge about the distributions of species. Furthermore, these factors can play a role in species morphological variation. Tadpoles can be found in different types of aquatic microhabitats, showing a considerable amount of morphological diversity. We hypothesized that tadpole morphological diversity is controlled by ecological and spatial factors other than assemblage attributes, and that tadpole assemblage composition is affected by spatial factors. To test these hypotheses, we recorded the abundance of tadpoles from different ponds, identified eight environmental variables that represented local and landscape descriptors of the ponds, recorded the spatial coordinates of the ponds, and measured the morphological variation of assemblages. Spatial factors significantly affected the composition of tadpole assemblages, while both spatial and environmental factors affected morphological variation. The ability of tadpoles to alter their morphology in response to environmental factors might be a result of poor oviposition site choice, and this probably interacts with spatial factors to control the assemblage composition of tadpoles. Morphological variation is advantageous for tadpoles because it allows them to adjust their morphology to environmental conditions. This study has demonstrated how factors that control the assemblage composition of tadpoles also drive their morphological diversity.

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The Relative Importance of Human Disturbance, Environmental and Spatial Factors on the Community Composition of Wetland Birds

Water ◽

10.3390/w13233448 ◽

2021 ◽

Vol 13 (23) ◽

pp. 3448

Author(s):

Seid Tiku Mereta ◽

Pieter Lemmens ◽

Luc De Meester ◽

Peter L. M. Goethals ◽

Pieter Boets

Keyword(s):

Community Composition ◽

Human Disturbance ◽

Environmental Variables ◽

Variation Partitioning ◽

Bird Species ◽

Bird Community ◽

Minor Role ◽

Compositional Variation ◽

Relative Importance ◽

Spatial Factors

The present study investigates the relative importance of human disturbance, local environmental and spatial factors on variations in bird community composition in natural Ethiopian wetlands with high biodiversity conservation value. We quantified bird abundances, local environmental variables and human disturbances at 63 sites distributed over ten wetlands in two subsequent years. Variation partitioning analyses were used to explore the unique and shared contributions of human disturbance, local environmental variables and spatial factors on variations in community compositions of wetland bird species. Local environmental variables explained the largest amount of compositional variation of wetland bird species. Productivity-related variables were the most important local environmental variables determining bird community composition. Human disturbance was also an important determinant for wetland bird community composition and affected the investigated communities mainly indirectly through its effect on local environmental conditions. Spatial factors only played a minor role in variations in bird community composition. Our study highlights the urgent need for integrated management approaches that consider both nature conservation targets and socio-economic development of the region for the sustainable use and effective conservation of wetland resources.

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Impact of fire frequency on woody community structure and soil nutrients in the Kruger National Park

Koedoe ◽

10.4102/koedoe.v43i1.210 ◽

2000 ◽

Vol 43 (1) ◽

Cited By ~ 33

Author(s):

C.M. Shackleton ◽

R.J. Scholes

Keyword(s):

Community Structure ◽

Soil Nutrients ◽

National Park ◽

Basal Area ◽

Fire Frequency ◽

Kruger National Park ◽

Fire Season ◽

Soil Variables ◽

And Function

Although fire is recognised as an important determinant of the structure and function of South African savannas, there are few studies of long-term impacts. Controlled burning blocks of contrasting fire season and frequency have been maintained throughout the Kruger National Park for almost 50 years. This paper reports on a quantitative study of the Satara plots to determine the long-term impacts of fire frequency on woody community structure and soil nutrients. Increasing fire frequency significantly decreased woody plant basal area, biomass, density, height, and mean stem circumference. The number of stems per plant and the proportion of regenerative stems increased with increasing fire frequency. Effects on species richness of woody plants were inconsistent. There were no significant differences attributable to fire frequency for any of the soil variables except organic matter and magnesium. Organic carbon was highest in the fire exclusion treatment and lowest in soils from plots burnt triennially. Magnesium levels were greatest in the annually burnt soils and least in the triennial plots.

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Effects of environmental factors and soil properties on soil organic carbon stock in a natural dry tropical area of Cameroon

10.5194/soil-2021-12 ◽

2021 ◽

Author(s):

Désiré Tsozué ◽

Nérine Mabelle Moudjie Noubissie ◽

Estelle Lionelle Tamto Mamdem ◽

Simon Djakba Basga ◽

Dieudonne Lucien Bitom Oyono

Keyword(s):

Environmental Factors ◽

Organic Carbon ◽

Soil Organic Carbon ◽

Soil Properties ◽

National Park ◽

Carbon Stock ◽

Forest Reserve ◽

Soil Organic Carbon Stock ◽

Tropical Area ◽

Organic Carbon Stock

Abstract. Researches carried out on soil organic carbon stock (SOCS) in the Sudano-Sahelian part of Cameroon are very rare. The few existing ones are mostly available in reports and concern in most cases carbon stocks in plant biomass. In order to contribute to the documentation on soils in this part of the country, the present work was designed to evaluate the SOCS in the main soil types and the influence of environmental factors and soil properties on these stocks under the natural dry tropical area of the Sudano-Sahelian zone of Cameroon. The study was undertaken in four sites, including three natural forest reserves (Laf, Zamai, Kosohon) and one national park (Mozogo), located at different latitudes. Two replications were thereafter made, thus, giving rise to three sampling points chosen per site, from 0 to 75 cm depth, for the determination of the SOCS. At each sampling point, soils were sampled using depth increments of 25 cm from the surface. The studied area is covered by Haplic Vertisols, Dystric Arenosols, Dystric Leptosols and Dystric Planosols. T-SOCS content, which refers to a depth of 75 cm, decreases with increasing latitude, with 249±26.26 Mg.ha-1 in Vertisols at Laf forest reserve in the low latitude, 199±8.00 Mg.ha-1 in Arenosols at Zamai forest reserve, 166±16.63 Mg.ha-1 in Leptosols at Kosohon forest reserve and 161±8.88 Mg.ha-1 in Planosols at Mozogo national park in the high latitude, regardless of the altitude. No significant correlation was noted between T-SOCS and the altitude. A good correlation was noted between precipitation which decreases with increasing latitude and T-SOCS, indicating the importance of climate in the distribution of T-SOCS in the study area, which directly influence the productivity of the vegetation. More than 60% of the SOCS was stored below the first 25 cm from the soil surface, a peculiarity of SOCS in the drylands. The SOCS in the Sudano-Sahelian area of Cameroon is mainly influenced by climate and vegetation.

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The relative importance of competition, microsite, and climate in controlling the stem taper and profile shape in jack pine

Canadian Journal of Forest Research ◽

10.1139/x92-261 ◽

1992 ◽

Vol 22 (12) ◽

pp. 1999-2003 ◽

Cited By ~ 11

Author(s):

Dave M. Morris ◽

R.R. Forslund

Keyword(s):

Environmental Factors ◽

Basal Area ◽

Jack Pine ◽

Stand Age ◽

Relative Importance ◽

Stem Size ◽

Profile Shape ◽

Total Height ◽

Canopy Opening ◽

Stem Taper

The purpose of this study was to identify the relative importance that environmental factors have on the taper and profile shape of mature jack pine (Pinusbanksiana Lamb.) stems. A total of 60 dominant trees from six different stands (10 per stand) were felled and measured to determine stem size, taper, and profile shape. Total height, basal age, and diameters at three locations (breast height, 20% total height, and 70% total height) were collected. The last two diameters were then used to calculate stem taper and profile shape. Data on competition (4 variables) and microsite (10 variables) were collected. Climatic variables (6) were interpolated from nearby weather station data. From the regression results, several environmental factors from all three categories (competition, microsite, and climate) proved to be important in determining taper and shape. The most relevant measures from each category, respectively, were percent canopy opening (taper) or total basal area (shape), slope, and growing degree-days. When combined in a multiple linear regression, these environmental variables, along with stand age, explained 61.9% of the variation in stem taper and 38.6% in stem shape. Although these values represent a significant portion of the variation in stem profile characteristics, further exploration into additional factors (e.g., bending and stress caused by wind action, nutrition, genetics) affecting stem taper and shape is required.

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