Terrestrial vegetation monitoring at Cape Hatteras National Seashore: 2019 data summary

The Southeast Coast Network (SECN) conducts long-term terrestrial vegetation monitoring as part of the nationwide Inventory and Monitoring Program of the National Park Service (NPS). The vegetation community vital sign is one of the primary-tier resources identified by SECN park managers, and monitoring is currently conducted at 15 network parks (DeVivo et al. 2008). Monitoring plants and their associated communities over time allows for targeted understanding of ecosystems within the SECN geography, which provides managers information about the degree of change within their parks’ natural vegetation. The first year of conducting this monitoring effort at four SECN parks, including 52 plots on Cape Hatteras National Seashore (CAHA), was 2019. Twelve vegetation plots were established at Cape Hatteras NS in July and August. Data collected in each plot included species richness across multiple spatial scales, species-specific cover and constancy, species-specific woody stem seedling/sapling counts and adult tree (greater than 10 centimeters [3.9 inches {in}]) diameter at breast height (DBH), overall tree health, landform, soil, observed disturbance, and woody biomass (i.e., fuel load) estimates. This report summarizes the baseline (year 1) terrestrial vegetation data collected at Cape Hatteras National Seashore in 2019. Data were stratified across four dominant broadly defined habitats within the park (Maritime Tidal Wetlands, Maritime Nontidal Wetlands, Maritime Open Uplands, and Maritime Upland Forests and Shrublands) and four land parcels (Bodie Island, Buxton, Hatteras Island, and Ocracoke Island). Noteworthy findings include: A total of 265 vascular plant taxa (species or lower) were observed across 52 vegetation plots, including 13 species not previously documented within the park. The most frequently encountered species in each broadly defined habitat included: Maritime Tidal Wetlands: saltmeadow cordgrass Spartina patens), swallow-wort (Pattalias palustre), and marsh fimbry (Fimbristylis castanea) Maritime Nontidal Wetlands: common wax-myrtle (Morella cerifera), saltmeadow cordgrass, eastern poison ivy (Toxicodendron radicans var. radicans), and saw greenbriar (Smilax bona-nox) Maritime Open Uplands: sea oats (Uniola paniculata), dune camphorweed (Heterotheca subaxillaris), and seabeach evening-primrose (Oenothera humifusa) Maritime Upland Forests and Shrublands: : loblolly pine (Pinus taeda), southern/eastern red cedar (Juniperus silicicola + virginiana), common wax-myrtle, and live oak (Quercus virginiana). Five invasive species identified as either a Severe Threat (Rank 1) or Significant Threat (Rank 2) to native plants by the North Carolina Native Plant Society (Buchanan 2010) were found during this monitoring effort. These species (and their overall frequency of occurrence within all plots) included: alligatorweed (Alternanthera philoxeroides; 2%), Japanese honeysuckle (Lonicera japonica; 10%), Japanese stilt-grass (Microstegium vimineum; 2%), European common reed (Phragmites australis; 8%), and common chickweed (Stellaria media; 2%). Eighteen rare species tracked by the North Carolina Natural Heritage Program (Robinson 2018) were found during this monitoring effort, including two species—cypress panicgrass (Dichanthelium caerulescens) and Gulf Coast spikerush (Eleocharis cellulosa)—listed as State Endangered by the Plant Conservation Program of the North Carolina Department of Agriculture and Consumer Services (NCPCP 2010). Southern/eastern red cedar was a dominant species within the tree stratum of both Maritime Nontidal Wetland and Maritime Upland Forest and Shrubland habitat types. Other dominant tree species within CAHA forests included loblolly pine, live oak, and Darlington oak (Quercus hemisphaerica). One hundred percent of the live swamp bay (Persea palustris) trees measured in these plots were experiencing declining vigor and observed with symptoms like those caused by laurel wilt......less

Projected Changes in Terrestrial Vegetation and Carbon Fluxes under 1.5 °C and 2.0 °C Global Warming

The terrestrial ecosystem plays a vital role in regulating the exchange of carbon between land and atmosphere. This study investigates how terrestrial vegetation coverage and carbon fluxes change in a world stabilizing at 1.5 °C and 2 °C warmer than pre-industrial level. Model results derived from 20 Earth System Models (ESMs) under low, middle, and high greenhouse emission scenarios from CMIP5 and CMIP6 are employed to supply the projected results. Although the ESMs show a large spread of uncertainties, the ensemble means of global LAI are projected to increase by 0.04 ± 0.02 and 0.08 ± 0.04 in the 1.5 and 2.0 °C warming worlds, respectively. Vegetation density is projected to decrease only in the Brazilian Highlands due to the decrease of precipitation there. The high latitudes in Eurasia are projected to have stronger increase of LAI in the 2.0 °C warming world compared to that in 1.5 °C warming level caused by the increase of tree coverage. The largest zonal LAI is projected around 70° N while the largest zonal NPP is projected around 60° N and equator. The zonally inhomogeneous increase of vegetation density and productivity relates to the zonally inhomogeneous increase of temperature, which in turn could amplify the latitudinal gradient of temperature with additional warming. Most of the ESMs show uniform increases of global averaged NPP by 10.68 ± 8.60 and 15.42 ± 10.90 PgC year−1 under 1.5 °C and 2.0 °C warming levels, respectively, except in some sparse vegetation areas. The ensemble averaged NEE is projected to increase by 3.80 ± 7.72 and 4.83 ± 10.13 PgC year−1 in the two warming worlds. The terrestrial ecosystem over most of the world could be a stronger carbon sink than at present. However, some dry areas in Amazon and Central Africa may convert to carbon sources in a world with additional 0.5 °C warming. The start of the growing season in the northern high latitudes is projected to advance by less than one month earlier. Five out of 10 CMIP6 ESMs, which use the Land Use Harmonization Project (LUH2) dataset or a prescribed potential vegetation distribution to constrain the future change of vegetation types, do not reduce the model uncertainties in projected LAI and terrestrial carbon fluxes. This may suggest the challenge in optimizing the carbon fluxes modeling in the future.

Terrestrial vegetation monitoring at Fort Pulaski National Monument: 2019 data summary

The Southeast Coast Network (SECN) conducts long-term terrestrial vegetation monitoring as part of the nationwide Inventory and Monitoring Program of the National Park Service (NPS). The vegetation community vital sign is one of the primary-tier resources identified by SECN park managers, and monitoring is currently conducted at 15 network parks (DeVivo et al. 2008). Monitoring plants and their associated communities over time allows for targeted understanding of ecosystems within the SECN geography, which provides managers information about the degree of change within their parks’ natural vegetation. 2019 marks the first year of conducting this monitoring effort on four SECN parks, including Fort Pulaski National Monument (FOPU). Twelve vegetation plots were established at Fort Pulaski National Monument in August. Data collected in each plot included species richness across multiple spatial scales, species-specific cover and constancy, species-specific woody stem seedling/sapling counts and adult tree (greater than 10 centimeters [3.9 inches {in}]) diameter at breast height (DBH), overall tree health, landform, soil, observed disturbance, and woody biomass (i.e., fuel load) estimates. This report summarizes the baseline (year 1) terrestrial vegetation data collected at Fort Pulaski National Monument in 2019. Data were stratified across two dominant broadly defined habitats within the park (Maritime Tidal Wetlands and Maritime Upland Forests and Shrublands). Noteworthy findings include: Sixty-six vascular plant taxa were observed across 12 vegetation plots, including six taxa not previously known from the park. Plots were located on both Cockspur and McQueen’s Island. The most frequently encountered species in each broadly defined habitat included: Maritime Tidal Wetlands: smooth cordgrass (Spartina alterniflora), perennial saltmarsh aster(Symphyotrichum enuifolium), and groundsel tree (Baccharis halimifolia) Maritime Upland Forests and Shrublands: yaupon (Ilex vomitoria), southern/eastern red cedar (Juniperus silicicola + virginiana), and cabbage palmetto (Sabal palmetto). Four non-native species identified as invasive by the Georgia Exotic Pest Plant Council (GA-EPPC 2018) were found during this monitoring effort. These species (and their overall frequency of occurrence within all plots) included: Japanese honeysuckle (Lonicera japonica; 17%), bahiagrass (Paspalum notatum; 8%), Vasey’s grass (Paspalum urvillei; 8%), and European common reed (Phragmites australis; 8%). Two rare plants tracked by the Georgia Department of Natural Resources (GADNR 2013) were found during this monitoring effort. These include Florida wild privet (Forestiera segregata) and Bosc’s bluet (Oldenlandia boscii). Southern/eastern red cedar and cabbage palmetto were the most dominant species within the tree stratum of the maritime Upland Forest and Shrubland habitat type. Species that dominated the sapling and seedling strata of this type included yaupon, cabbage palmetto, groundsel tree, and Carolina laurel cherry (Prunus caroliniana). The health status of sugarberry (Celtis laevigata)—a typical canopy species in maritime forests of the South Atlantic Coastal Plain--observed on park plots appeared to be in decline, with most stems experiencing elevated levels of dieback and low vigor. Over the past decade, this species has been experiencing unexplained high rates of dieback and mortality throughout its range in the Southeastern United States; current research is focusing on what may be causing these alarming die-off patterns. Duff and litter made up the majority of downed woody biomass (fuel loads) across FOPU vegetation plots.

Natural and anthropogenic sources of extractable organic matter in sediments from the coastal zone of the Arabian Gulf in Saudi Arabia

Surface sediment samples from the Arabian Gulf coast of Saudi Arabia were collected by Van Veen grab sampler to identify the characteristics, distribution, levels, and to discriminate between natural and anthropogenic sources of the total extractable organic matter (TEOM). The dried and sieved sediments were extracted with a dichloromethane/methanol mixture for analysis by gas chromatography-mass spectrometry. The TEOM included n-alkanes (353.9±283.8 ng.g−1), n-alkanols (283.2±296.1 ng.g−1), fatty acid methyl esters (245.2±353.7 ng.g−1), hopanes (100.7±158.2 ng.g−1), steranes (58.5±96.3 ng.g−1), triterpenoids (18.9±21.1 ng.g−1), steroids (15.3±17.0 ng.g−1), polycyclic aromatic hydrocarbons (PAHs) (0.48±1.19 ng.g−1), as well as an unresolved complex mixture (UCM =1633±3151 ng.g−1) and petrochemicals (343.1±424.2 ng.g−1). The major sources of these TEOM compound groups were anthropogenic (petroleum and petrochemical) and natural (lipids from higher plants, marine material, and microbiota) inputs. Anthropogenic contaminants from petroleum products ranged from 46.6-85.6% of the TEOM, whereas petrochemicals varied from 10.7-40.6%. Biogenic influx from terrestrial vegetation ranged from 5.7-19.3%, and marine biotic sources varied from 11.1-37.5%. The continuous accumulation of anthropogenic contaminants will ultimately affect the critical habitats of this marine coastal region. This provides a basis for further studies to understand human and developmental activities on delivery, deposition processes, distribution, and biogeochemical alteration of organic matter in the coastal zones of the Arabian Gulf. Such studies are important for sustainable development and protection of these key regional habitats.

The Indian Ocean SST Link to Solar Induced Chlorophyll Fluorescence Over India During Early Summer Monsoon

This is a maiden attempt to explore the influence of sea surface temperature (SST) variations in the tropical Indian Ocean on the gross primary productivity (GPP) of the terrestrial vegetation of India during the summer monsoon. We studied the productivity of the vegetation across India using solar-induced chlorophyll fluorescence (SIF) as a proxy. Our results demonstrated a strong negative SST–SIF relationship: the productivity decreases (increases) when the SST of the tropical Indian Ocean is higher (lower) than normal. This SST–SIF coupling observed during June can be explained through the atmospheric teleconnections. Positive SST anomalies weaken the land–ocean thermal gradient during the monsoon onset period, reduce the monsoon flow, and hence decrease the moisture transport from the ocean to the Indian mainland. The resultant water stress, along with the high air temperature, leads to a reduction in the GPP. Conversely, negative SST anomalies strengthen the monsoon and increase the availability of moisture for photosynthesis. There is scope for improving regional GPP forecasting studies using the observed SST–SIF relationships.

The Influence of Ozone on Net Ecosystem Production of a Ryegrass–Clover Mixture under Field Conditions

In order to understand the effect of phytotoxic tropospheric ozone (O3) on terrestrial vegetation, we quantified the impact of current O3 concentration ([O3]) on net ecosystem production (NEP) when compared to the conditions of the pre-industrial era. We compared and tested linear mixed-effects models based on [O3] and stomatal O3 flux (Fsto). The managed ryegrass–clover (Lolium perenne and Trifolium pratense) mixture was grown on arable land in the Czech Republic, Central Europe. Values of [O3] and Fsto were measured and calculated based on resistance analogy, respectively, while NEP was calculated from eddy covariance CO2 fluxes. We found the Fsto-based model more precise when compared to measured NEP. High Fsto was found even at low [O3], while broad summer maximum of [O3] was not necessarily followed by significant NEP decline, due to low soil water content leading to a low stomatal conductivity and Fsto. Comparing to low pre-industrial O3 conditions, current levels of O3 resulted in the reduction of cumulative NEP over the entire growing season, up to 29.7 and 13.5% when the [O3]-based and Fsto-based model was applied, respectively. During the growing season, an O3-induced reduction of NEP ranged between 13.1% in May and 26.2% in July when compared to pre-industrial Fsto levels. Looking to the future, high [O3] and Fsto may lead to the reduction of current NEP by approximately 13.3% on average during the growing season, but may increase by up to 61–86.6% in autumn, indicating further O3-induced acceleration of the senescence. These findings indicate the importance of Fsto and its inclusion into the models estimating O3 effects on terrestrial vegetation. The interaction between environmental factors and stomatal conductance is therefore discussed in detail.