Synecological effects of cattle grazing riparian ecosystems

In 1978, a ten year project was begun to examine the synecological effects of livestock grazing riparian ecosystems. A multitude of biotic arid physical factors, many which were unique to riparian ecosystems, interacted to form a complex and diverse riparian ecosystem. A total of 256 stands of vegetation representing 60 discrete plant communities were identified. Twenty species of mammals and 81 species of birds were sited utilizing the area from May-October. Approximately one-half of the riparian vegetation bordering Catherine Creek was excluded from livestock grazing. Ten plant communities were intensively sampled in grazed and exclosed areas during three growing seasons to determine some of the impacts a late season grazing scheme has on riparian vegetation. Three plant communities displayed significant species composition and productivity differences. These commmunities were within' the meadow and Doug1az Hawthorne (Crataegus douglasii) vegetation types and were utilized more heavily by livestock than any other communities sampled. In addition succession appeared to be retarded by grazing on gravel bars dominated by black cottonwood (Populus trichocarpa) saplings and willows (Salix spp.). Few differences were recorded in other plant communities sampled. Late season grazing had few short term impacts on avian populations censused from May-October. There was a significant decrease in small mammal populations after grazing in all communities sampled. However, by the following August small mammals had recolonized the grazed plant communities in essentially the same species composition and densities. Grazed areas had significantly greater streambank losses than areas that were not grazed. While overwinter losses accounted for much of the streambank erosion, the erosion and disturbance caused by livestock grazing and trampling was enough to create significantly greater streambank losses in grazed areas compared to ungrazed areas. Positive characteristics of a late season grazing scheme on. the riparian zone included increased late season livestock production, good plant vigor and productivity, minimal soil disturbance, and minimal short term disturbance to wildlife populations dependent on riparian ecosystems

Bison Influences on Composition and Diversity of Riparian Plant Communities in Yellowstone National Park

Riparian zones are among the most biologically diverse ecosystems in the Intermountain West, USA, and provide valuable ecosystem services, including high rates of biotic productivity, nutrient processing, and carbon storage. Thus, their sustainability is a high priority for land managers. Large ungulates affect composition and structure of riparian/stream ecosystems through herbivory and physical effects, via trailing and trampling. Bison (Bison bison) in Yellowstone National Park (YNP) have been characterized as ecosystem engineers because of their demonstrated effects on phenology, aboveground productivity of grasses, and woody vegetation structure. Bison have greatly increased in numbers during the last two decades and spend large periods of time in the broad open floodplains of the Northern Range of the Park, where they are hypothesized to have multiple effects on plant species composition and diversity. We sampled indicators of bison use as well as riparian vegetation composition, diversity, and structure along eight headwater streams within YNP\u27s Northern Range. Total fecal density ranged from 333 to 1833 fecal chips and/or piles/ha, stubble heights ranged from 7 to 49 cm, and streambank disturbance ranged from 9% to 62%. High levels of bison use were positively correlated with exotic species dominance and negatively correlated with species richness, native species diversity, willow (Salix spp.) cover, and wetland species dominance. At three sites, the intensity of bison use exceeded recommended utilization thresholds to avoid degradation of streams and riparian zones on public lands. The influences of large herbivores, principally bison, on vegetation composition and structure suggest the cumulative effects of the current densities on the Northern Range are contributing to biotic impoverishment, representing the loss of ecosystem services that are provided by native riparian plant communities. In addition, contemporary levels of bison use may be exacerbating climate change effects as observed through ungulate-related shifts in composition toward plant assemblages adapted to warmer and drier conditions. However, the resilience of native riparian vegetation suggests that sites currently heavily utilized by bison would have the potential for recovery with a reduction in pressure by this herbivore

Bison influences on composition and diversity of riparian plant communities in Yellowstone National Park

Riparian zones are among the most biologically diverse ecosystems in the Intermountain West, USA, and provide valuable ecosystem services, including high rates of biotic productivity, nutrient processing, and carbon storage. Thus, their sustainability is a high priority for land managers. Large ungulates affect composition and structure of riparian/stream ecosystems through herbivory and physical effects, via trailing and trampling. Bison (Bison bison) in Yellowstone National Park (YNP) have been characterized as “ecosystem engineers” because of their demonstrated effects on phenology, aboveground productivity of grasses, and woody vegetation structure. Bison have greatly increased in numbers during the last two decades and spend large periods of time in the broad open floodplains of the Northern Range of the Park, where they are hypothesized to have multiple effects on plant species composition and diversity. We sampled indicators of bison use as well as riparian vegetation composition, diversity, and structure along eight headwater streams within YNP’s Northern Range. Total fecal density ranged from 333 to 1833 fecal chips and/or piles/ha, stubble heights ranged from 7 to 49 cm, and streambank disturbance ranged from 9% to 62%. High levels of bison use were positively correlated with exotic species dominance and negatively correlated with species richness, native species diversity, willow (Salix spp.) cover, and wetland species dominance. At three sites, the intensity of bison use exceeded recommended utilization thresholds to avoid degradation of streams and riparian zones on public lands. The influences of large herbivores, principally bison, on vegetation composition and structure suggest the cumulative effects of the current densities on the Northern Range are contributing to biotic impoverishment, representing the loss of ecosystem services that are provided by native riparian plant communities. In addition, contemporary levels of bison use may be exacerbating climate change effects as observed through ungulate-related shifts in composition toward plant assemblages adapted to warmer and drier conditions. However, the resilience of native riparian vegetation suggests that sites currently heavily utilized by bison would have the potential for recovery with a reduction in pressure by this herbivore

Biomass and nutrient dynamics associated with slash fires in neotropical dry forests

Unprecedented rates of deforestation and biomass burning in tropical dry forests are dramatically influencing biogeochemical cycles, resulting in resource depletion, declines in biodiversity, and atmospheric pollution. We quantified the effects of defores- tation and varying levels of slash-fire severity on nutrient losses and redistribution in a second-growth tropical dry forest ("Caatinga") near Serra Talhada, Pernambuco, Brazil. Total aboveground biomass prior to burning was 74 Mg/ha. Nitrogen and phosphorus concentrations were highest in litter, leaves attached to slash, and fine wood debris (<0.64 cm diameter). While these components comprised only 30% of the prefire aboveground biomass, they accounted for -60% of the aboveground pools of N and P. Three experi- mental fires were conducted during the 1989 burning season. In these treatments con- sumption was 78, 88, and 95% of the total aboveground biomass. As much as 96% of the prefire aboveground N and C pools and 56% of the prefire aboveground P pool was lost during combustion processes. Nitrogen losses exceeded 500 kg/ha and P losses exceeded 20 kg/ha in the fires of the greatest severity. With increasing fire severity, the concentrations of N and P in ash decreased while the concentration of Ca increased. This indicates greater amounts of these nutrients were volatilized (i.e., greater ecosystem losses occurred) with increasing fire severity. Following fire, up to 47% of the residual aboveground N and 84% of the residual aboveground P were in the form of ash, which was quickly lost from the site via wind erosion. Fires appeared to have a minor immediate effect on total N, C, or P in the soils. However, soils in forests with no history of cultivation had significantly higher concentrations of C and P than second-growth forests. Based upon the measured losses of nutrients from these single slash-burning events, it would likely require a century or more of fallow for reaccumulation to occur. However, current fallow periods in this region are 15 yr or less

Carbon stocks of intact mangroves and carbon emissions arising from their conversion in the Dominican Republic

Mangroves are recognized to possess a variety of ecosystem services including high rates of carbon sequestration and storage. Deforestation and conversion of these ecosystems continue to be high and have been predicted to result in significant carbon emissions to the atmosphere. Yet few studies have quantified the carbon stocks or losses associated with conversion of these ecosystems. In this study we quantified the ecosystem carbon stocks of three common mangrove types of the Caribbean as well as those of abandoned shrimp ponds in areas formerly occupied by mangrove—a common land-use conversion of mangroves throughout the world. In the mangroves of the Montecristi Province in Northwest Dominican Republic we found C stocks ranged from 706 to 1131 Mg/ha. The medium-statured mangroves (3–10 m in height) had the highest C stocks while the tall (>10 m) mangroves had the lowest ecosystem carbon storage. Carbon stocks of the low mangrove (shrub) type (<3 m) were relatively high due to the presence of carbon-rich soils as deep as 2 m. Carbon stocks of abandoned shrimp ponds were 95 Mg/ha or ~11% that of the mangroves. Using a stock-change approach, the potential emissions from the conversion of mangroves to shrimp ponds ranged from 2244 to 3799 Mg CO2e/ha (CO2 equivalents). This is among the largest measured C emissions from land use in the tropics. The 6260 ha of mangroves and converted mangroves in the Montecristi Province are estimated to contain 3 841 490 Mg of C. Mangroves represented 76% of this area but currently store 97% of the carbon in this coastal wetland (3 696 722 Mg C). Converted lands store only 4% of the total ecosystem C (144 778 Mg C) while they comprised 24% of the area. By these metrics the replacement of mangroves with shrimp and salt ponds has resulted in estimated emissions from this region totaling 3.8 million Mg CO2e or ~21% of the total C prior to conversion. Given the high C stocks of mangroves, the high emissions from their conversion, and the other important functions and services they provide, their inclusion in climate-change mitigation strategies is warranted.Keywords: Blue carbon, REDD+, Climate-change mitigation, Carbon stocks, Land use, CO₂e emissions, Coastal ecosystems, Mangroves, Shrimp pond

Carbon accumulation of tropical peatlands over millennia: a modeling approach

Tropical peatlands cover an estimated 440,000 km² (~10% of global peatland area) and are significant in the global carbon cycle by storing about 40–90 Gt C in peat. Over the past several decades, tropical peatlands have experienced high rates of deforestation and conversion, which is often associated with lowering the water table and peat burning, releasing large amounts of carbon stored in peat to the atmosphere. We present the first model of long-term carbon accumulation in tropical peatlands by modifying the Holocene Peat Model (HPM), which has been successfully applied to northern temperate peatlands. Tropical HPM (HPMTrop) is a one-dimensional, nonlinear, dynamic model with a monthly time step that simulates peat mass remaining in annual peat cohorts over millennia as a balance between monthly vegetation inputs (litter) and monthly decomposition. Key model parameters were based on published data on vegetation characteristics, including net primary production partitioned into leaves, wood, and roots; and initial litter decomposition rates. HPMTrop outputs are generally consistent with field observations from Indonesia. Simulated long-term carbon accumulation rates for 11,000-year-old inland, and 5,000-year-old coastal peatlands were about 0.3 and 0.59 Mg C ha⁻¹ yr⁻¹, and the resulting peat carbon stocks at the end of the 11,000-year and 5,000-year simulations were 3,300 and 2,900 Mg C ha⁻¹, respectively. The simulated carbon loss caused by coastal peat swamp forest conversion into oil palm plantation with periodic burning was 1,400 Mg C ha⁻¹ over 100 years, which is equivalent to ~2,900 years of C accumulation in a hectare of coastal peatlands.This is the publisher’s final pdf. The published article is copyrighted by John Wiley & Sons Ltd. and can be found at: http://onlinelibrary.wiley.com/journal/10.1111/%28ISSN%291365-2486.Keywords: oil palm, peat swamp forests, peat carbon stocks, carbon sequestration, holocene, land-use chang

Ecology and plant communities of the riparian area associated with Catherine Creek in northeastern Oregon

Published March 1985. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalo

Carbon Stocks of Tropical Coastal Wetlands within the Karstic Landscape of the Mexican Caribbean

Coastal wetlands can have exceptionally large carbon (C) stocks and their protection and restoration would constitute an effective mitigation strategy to climate change. Inclusion of coastal ecosystems in mitigation strategies requires quantification of carbon stocks in order to calculate emissions or sequestration through time. In this study, we quantified the ecosystem C stocks of coastal wetlands of the Sian Ka'an Biosphere Reserve (SKBR) in the Yucatan Peninsula, Mexico. We stratified the SKBR into different vegetation types (tall, medium and dwarf mangroves, and marshes), and examined relationships of environmental variables with C stocks. At nine sites within SKBR, we quantified ecosystem C stocks through measurement of above and belowground biomass, downed wood, and soil C. Additionally, we measured nitrogen (N) and phosphorus (P) from the soil and interstitial salinity. Tall mangroves had the highest C stocks (987 ± 338 Mg ha⁻¹) followed by medium mangroves (623 ± 41 Mg ha⁻¹), dwarf mangroves (381 ± 52 Mg ha⁻¹) and marshes (177 ±73 Mg ha⁻¹). At all sites, soil C comprised the majority of the ecosystem C stocks (78-99%). Highest C stocks were measured in soils that were relatively low in salinity, high in P and low in N: P, suggesting that P limits C sequestration and accumulation potential. In this karstic area, coastal wetlands, especially mangroves, are important C stocks. At the landscape scale, the coastal wetlands of Sian Ka'an covering approximate to ≈172,176 ha may store 43.2 to 58.0 million Mg of C.Keywords: Ignition, Sea level, Mangrove forests, Enrichment, Organic matter, Florida, Biomass, Sediments, Nutrient dynamics, Brazilian AmazonKeywords: Ignition, Sea level, Mangrove forests, Enrichment, Organic matter, Florida, Biomass, Sediments, Nutrient dynamics, Brazilian Amazo

The potential of Indonesian mangrove forests for global climate change mitigation

Mangroves provide a wide range of ecosystem services, including nutrient cycling, soil formation, wood production, fish spawning grounds, ecotourism and carbon (C) storage¹. High rates of tree and plant growth, coupled with anaerobic, water-logged soils that slow decomposition, result in large long-term C storage. Given their global significance as large sinks of C, preventing mangrove loss would be an effective climate change adaptation and mitigation strategy. It has been reported that C stocks in the Indo-Pacific region contain on average 1,023 MgC ha⁻¹ (ref. 2). Here, we estimate that Indonesian mangrove C stocks are 1,083 ± 378 MgC ha⁻¹. Scaled up to the country-level mangrove extent of 2.9 Mha (ref. 3), Indonesia’s mangroves contained on average 3.14 PgC. In three decades Indonesia has lost 40% of its mangroves⁴, mainly as a result of aquaculture development⁵. This has resulted in annual emissions of 0.07–0.21 Pg CO₂e. Annual mangrove deforestation in Indonesia is only 6% of its total forest loss⁶; however, if this were halted, total emissions would be reduced by an amount equal to 10–31% of estimated annual emissions from land-use sectors at present. Conservation of carbon-rich mangroves in the Indonesian archipelago should be a high-priority component of strategies to mitigate climate change