Similar Vegetation Cover Research Articles

Pile burning after conifer removal from aspen stands affects tree mortality, regeneration, and understory recovery

Quaking aspen (Populus tremuloides Michx.) stands throughout the western United States provide valuable ecosystem services but can be lost via succession from aspen to conifer. Forest managers are cutting conifers, but disposal of cut wood can be challenging in remote or sensitive areas. Piling and burning is being tested within aspen stands but ecosystem responses to this treatment are understudied. We assessed aspen tree mortality, tree regeneration, and understory vegetation after forest restoration thinning followed by pile burning in seven aspen-conifer stands around Lake Tahoe, California and Nevada, USA. Pile burning was conducted after cut wood had dried (1.5–7.5 years post cutting). Pile burning was more likely to kill aspen trees closer to piles regardless of tree size or pile size. Aspen regenerated rapidly inside the footprint of some burned piles, more often inside piles located in close proximity to other aspen, presumably by suckering from lateral roots beneath burned piles. Similarly, areas where higher densities of conifers were regenerating naturally were indicative of a greater likelihood for conifer regeneration inside pile footprints. Understory vegetation varied within and among study sites, and had similar vegetation cover and species richness inside pile footprints to vegetation in the vicinity of each pile. Overall, understory vegetation had mostly recovered after 2.5–8.5 years since pile burning. Thinning followed by burning of hand piles and smaller machine piles appears to be effective at promoting regeneration of aspen without lasting impact on understory vegetation. However, without further disturbance such as continued cutting and piling or use of prescribed fire, we caution that succession to conifer appears to continue, albeit slowly, via seedling regeneration.

Grassland reconstruction in a factory yard increases biodiversity and reduces costs of installation and maintenance

AbstractAimsThe restoration of unused urban‐industrial areas has great conservation potential as it can sometimes create a win‐win situation in terms of nature conservation and economic benefits. Financial data of restoration projects are rarely published. To close this gap, we report the cost–benefit analysis of different landscaping methods used in the greening of the outskirts of a factory industrial area.LocationThe study area is located in a factory area in Nyíregyháza, Nyírség, Hungary.MethodsIn this study, we compare the costs of the implementation and maintenance of three different types of grasslands (intensively and extensively managed park lawns and semi‐natural grassland, called eco area) and the ecological benefits in terms of vegetation and potential for pollinators.ResultsThe implementation and maintenance costs of the extensively managed park lawn were more than ten‐fold higher than that of the eco area, despite the higher price of native plant material. The construction of the extensive park lawn is the cheapest, but the eco area pays off in ca. 1.5 years compared to it, taking into account the lower maintenance costs. Seven years after implementation, the eco area is the most species‐rich, hosting the highest number of natural constituent species, but with similar vegetation cover as in the intensively managed park lawn without costly maintenance. The cover and species richness of legumes and forbs are also higher in the eco area, ensuring a food source for pollinators.ConclusionsOur results support that introducing species‐rich and diverse grasslands with native, habitat specialist species as an alternative to traditional landscaping in urban‐industrial areas can be economically and ecologically rewarding. The higher costs of planning, plant material, and implementation pay off in a short time due to low maintenance costs and can lead to a win‐win situation for nature as well as for the local economy.

Assessment of soil erosion under long-term projections of climate change in Poland

Soil is a major natural resource fundamental for food production, and a habitat for living organisms. It is therefore extremely important to prevent its erosion. It is assumed that 50% of erosion at the global scale is caused by water. A relatively low number of studies model soil loss in Northern and Eastern Europe. Although that region currently contributes to total soil loss the least, the projected long-term climate change in Europe is likely to affect soil loss due to changes in rainfall characteristics. This study quantifies historical soil loss rates based on high-resolution datasets, and assesses the impact of the projected climate change on long-term average annual soil erosion rates in Poland, located in the temperate climate zone, using the Revised Universal Soil Loss Equation (RUSLE) model. The study investigates the projected changes for two future time horizons, namely: 2021-2050 (near future – NF) and 2071-2100 (far future – FF), under two different Representative Concentration Pathways (RCP) 4.5 and 8.5. To account for the uncertainty of individual climate models, an ensemble of nine EURO-CORDEX model scenarios was used. Based on the multi-model ensemble median, the average soil erosion rate in Poland for the historical period is 0.48 t ha−1 yr−1. The total annual soil loss in Poland is estimated at 14 Mt. The highest soil loss rate is observed in the south of Poland with mean annual erosion rate of 1.7 t ha−1 yr−1. Although it occupies only 16% of the territory of Poland, its share in total soil loss in the country is 62% (8.6 Mt year−1). The average projected potential soil erosion by water in the future increases gradually, reaching +7% (RCP4.5 NF), +8% (RCP8.5 NF), +13% (RCP4.5 FF), and +18% (RCP8.5 FF). The results of this study might be valuable for the development of the national soil conservation policy. The study fills the spatial gap in modelling of changes in soil erosion caused by climate in the Northern and Eastern part of Europe. Due to the lack of other national studies in the region, the directions of such changes could be transferrable to countries in the same climate zones, with a similar vegetation cover structure.

Experimental sediment addition in salt-marsh management: Plant-soil carbon dynamics in southern New England

Thin Layer Placement (TLP) is an increasingly used management technique to promote coastal resilience to accelerated sea level rise, but it is unclear how differential thickness of dredged sediment application alters plant-soil carbon dynamics in northeastern Atlantic coast salt marshes. We initiated a field experiment in a microtidal Spartina alterniflora (smooth cordgrass) dominated salt marsh in Connecticut (USA) to examine how a silt-loam dredge applied at different thicknesses (low: +5 cm, medium: +10 cm, and high: +15 cm) altered biological and biogeochemical responses. Over two growing seasons we monitored plant responses (above and belowground biomass, stem height, stem density, leaf area) and soil-biogeochemical parameters (EC, pH, redox, NH4+, sulfides, C:N, decomposition, bulk density, carbon fluxes). We found adding 5–7 cm of dredged sediment promoted rapid revegetation, alleviated phytotoxic sulfides, enhanced CO2 uptake, and reduced CH4 emissions. Low treatments reached similar vegetation cover to controls after one growing season, though sediment treatments greater than 10-cm thick showed delayed growth. Low levels of sediment addition stimulated the highest root biomass in the underlying soil, promoting CO2 efflux, but this was offset by aboveground biomass productivity, promoting net CO2 uptake. Phytotoxic sulfides were reduced in all sediment addition treatments, but our data indicate that coastal managers aiming to promote rapid vegetative recovery while increasing elevation in the short term should target conservative depths (< 10 cm) when using fine-grained dredged material. Collectively, our work will guide wetland managers as they develop restoration specifications for perpetuating coastal marshes in the face of rising seas.

Estimating soil salinity with different fractional vegetation cover using remote sensing

AbstractSoil salinization is a serious restrictive factor affecting sustainable agricultural development. In order to explore the effect of Fractional Vegetation Cover (FVC), we monitored soil salinization in sites different vegetation coverage in Jiefangzha Irrigation District in Inner Mongolia using satellite remote sensing. From May to August 2018, we carried out field sampling at different depths in each month, and calculated FVC and spectral covariates using GF‐1 satellite images in the corresponding sampling period. Based on the FVC division criteria for Inner Mongolia, we took the following steps: (a) setting up a control treatment A (the full data with undivided FVC, TA) and experimental treatments B (bare land, TB), C (mid‐low FVC, TC), D (mid FVC, TD) and E (high FVC, TE); (b) conducting the Best Subset Selection (BSS) for all spectral covariates at different depths of each treatment; and (c) constructing the Soil Salt Content (SSC) inversion models using partial least square regression (PLSR), Cubist, and Extreme Learning Machine (ELM). The results indicated that (a) classifying FVC could improve the stability and predictive ability of the models; (b) the performance of the three modeling methods were different (Cubist was the best, ELM next and PLSR the poorest); (c) the optimal inversion models for TB, TC and TE were constructed by Cubist at 0–20, 0–40 and 0–20 cm, and for TD was constructed by ELM at 0–60 cm, respectively. The results can provide references for soil salinization prevention and agricultural production in Jiefangzha Irrigation District and other areas with the similar vegetation cover.

Long-Term Nitrogen Addition Does Not Increase Soil Carbon Storage or Cycling Across Eight Temperate Forest and Grassland Sites on a Sandy Outwash Plain

Experimental nitrogen (N) deposition generally inhibits decomposition and promotes carbon (C) accumulation in soils, but with substantial variation among studies. Differences in ecosystem properties could help explain this variability: N could have distinct effects on decomposition and soil C due to differences in vegetation characteristics (that is, root C inputs and chemistry) that influence microbial biomass or soil properties like pH that can affect organic matter stabilization. We used a 12-year N addition experiment to determine effects of sustained N addition on soil C pool sizes and cycling across different grassland, conifer and deciduous forest sites in Minnesota, USA, while controlling for soil type and climate. We conducted a year-long soil incubation, and fit one- and two-pool decay models to respiration data to identify C pool sizes and decay rates. Contrary to previous studies, we found no consistent effects of N on soil C across sites: soil C stocks, microbial respiration, soil C decay rates and pool sizes all showed no general response to N in these sandy soils. Nevertheless, microbial biomass, microbial respiration, and the root biomass C pool responses to N addition were highly correlated, suggesting that soil C responses were ultimately driven by fine root biomass C responses to N addition, which in turn affected microbial biomass. However, the inconsistent directional responses to N among sites with similar vegetation cover highlight that N addition effects can be site-specific and raise caution for broad extrapolation of results from individual systems to global models.

Evaluation of six satellite-derived Fraction of Absorbed Photosynthetic Active Radiation (FAPAR) products across the Australian continent

Satellite remote sensing products of the Fraction of Absorbed Photosynthetically Active Radiation (FAPAR) are routinely used for diverse applications in Earth-System and land-surface modelling and monitoring. The availability of numerous products creates a need to understand the level of consistency between products, and reasons for inconsistencies. We evaluate the consistency of six FAPAR products (MODIS, MERIS, SeaWIFS, MODIS-TIP, SPOT-VEG, and AVHRR) across the Australian continent, using multi-year records. We find that seemingly large differences in FAPAR products over much of Australia can be explained by a simple offset present in certain products. Additional inconsistencies arise from different sensitivities in FAPAR to changes in vegetation cover. These inconsistencies can in turn be partially attributed to changes in biome type that are relevant to certain products and related model-specific assumptions.The satellite FAPAR products are compared to ~800 observation-based estimates of fractional vegetation cover at field sites across Australia. After accounting for offsets in FAPAR, relatively high agreement occurs at sites classified as grasslands, shrublands and managed land (agriculture). Significant disagreement occurs at sites correctly classified as forests. Consequently, some products show significant differences in FAPAR between regions of similar vegetation cover but different biome classification. We find that all products show a much lower sensitivity to fractional vegetation cover (range in coefficient of linear regression: 0.28–0.61) than is predicted theoretically (0.96–1.18) using a canopy radiative transfer model. Reasons for this discrepancy are discussed.

The hydrology of the Bois-des-Bel bog peatland restoration: 10 years post-restoration

Restoration measures (ditch blocking, bund construction, etc.) were applied to a cutover part of the Bois-des-Bel (BdB) bog peatland in autumn 1999; since then a near complete cover of Sphagnum rubellum (∼15cm) has developed over the old cutover peat, along with a suite of bog vegetation. This research assesses the restored site's (RES) hydrological condition after 10 growing seasons (May 15th–August 15th, 2010) through comparison with an adjacent unrestored site (UNR) and a natural site (NAT) located elsewhere in the peatland. Evapotranspiration (ET) from RES (242mm) has not noticeably changed since the first 3 years post-restoration (2000–2002) still maintaining lower ET rates than UNR (290mm). The highest ET occurred at NAT (329mm), dissimilar to RES despite similar vegetation cover. UNR generates more runoff (37mm) than RES (7mm), similar to the initial assessments. However, since the initial assessments the average water table has continued to rise, from −35.3 (±6.2)cm (2000–2002) to −27.3 (±14.9)cm (2010) below the cutover peat surface but still fluctuates predominantly within the cutover peat and not the regenerated Sphagnum. The regenerated Sphagnum at RES has increased the surface elevation by ∼15–20cm, and with respect to its surface the average water table was at ∼−42.3 (±20.9)cm. However, its water table was still lower (and more variable) than at NAT (33.2±9.0cm), with respect to the moss surface. Average soil water pressures in 2010 were similar to the early post-restoration condition at depths of 10cm (−43.0±12.2 and −44.1±13.1mb) and 20cm (−41.4±13.0 and −40.6±10.5mb) below the cutover surface at RES and UNR, respectively. Volumetric soil moisture contents (θ) at 2.5, 7.5 and 17.5cm depths were higher in the Sphagnum moss at NAT (0.23, 0.31, and 0.71) compared to RES (0.12, 0.11, and 0.23), where the underlying cutover peat had a relatively high θ of 0.74. The low moisture content in the new moss overlying the relatively moist cutover peat indicates there was restricted connectivity between the two layers. Ten years following the implementation of restoration measures and the development of a near complete 15cm thick Sphagnum moss layer, further time is required for the moss layer to develop (increase in thickness and bulk density, hence water retention capacity) and more consistently host the water table, so that the average water content more closely mimics NAT.

Measurement of the connectivity of runoff source areas as determined by vegetation pattern and topography: A tool for assessing potential water and soil losses in drylands

The connectivity of runoff sources is considered one of the main factors controlling the hydrology of sparsely vegetated landscapes. However, the empirical demonstration of this role is very limited, partly because of the scarcity of suitable connectivity metrics. In this work, we derived and tested a spatial metric, Flowlength, for quantifying the connectivity of runoff source areas considering both vegetation pattern and topography. Flowlength is calculated as the average of the runoff pathway lengths from all the cells in a raster‐based map of the target site. We evaluated the relationships between the connectivity of runoff sources, measured with Flowlength, and the runoff and sediment yields from six plots and three catchments in semiarid southeast Spain. Flowlength distinguished varying degrees of connectivity between differing vegetation patterns with similar vegetation cover. The connectivity increased with the grain size of the bare areas and was positively related to plot runoff and sediment yields. Flowlength also correctly ranked the three catchments according to total runoff yielded during the study period. The inclusion of microtopographic information in the quantification of Flowlength improved the relationships between the pattern of runoff sources and the measured fluxes, highlighting the importance of topographic features in the connectivity of surface flows. In general, the microtopography had a net decreasing effect on the connectivity, which was mainly attributed to an increase in the amount of runoff sink areas caused by the sediment terracettes developed upslope of plants. Our results confirm that the connectivity of runoff sources is a key factor controlling runoff and erosion in semiarid lands and support the potential of Flowlength as a surrogate for the hydrological functioning of ecosystems with patchy vegetation.