scholarly journals Vegetation Succession and Environmental Conditions following Catastrophic Lake Drainage in Old Crow Flats, Yukon

ARCTIC ◽  
2017 ◽  
Vol 70 (2) ◽  
pp. 177 ◽  
Author(s):  
Trevor C. Lantz
Keyword(s):  
Vegetation Succession ◽  
Wildlife Habitat ◽  
Soil Conditions ◽  
Field Sampling ◽  
Vegetation Development ◽  
Lake Drainage ◽  
Local Hydrology ◽  
Old Crow Flats ◽  
Lake Basins

Increases in the frequency and magnitude of disturbances associated with the thawing of ice-rich permafrost highlight the need to understand long-term vegetation succession in permafrost environments. This study uses field sampling and remote sensing to explore vegetation development and soil conditions following catastrophic lake drainage in Old Crow Flats (OCF). The data presented show that vegetation on drained lake basins in OCF is characterized by two distinct assemblages: tall willow stands and sedge swards. Field sampling indicates that these alternative successional trajectories result from variation in soil moisture following drainage. Increased willow mortality on older drained basins suggests that intraspecific competition drives self-thinning in shrub thickets. This finding, combined with data from paleoecological studies and contemporary vegetation in OCF, suggests that willow stands on drained lake basins are seral communities. These results also indicate that the increase in number of catastrophic drainages that occurred between 1972 and 2010 will alter regional vegetation in ways that affect wildlife habitat, permafrost conditions, and local hydrology.

scholarly journals Isotopic evidence of increasing water abundance and lake hydrological change in Old Crow Flats, Yukon, Canada

2021 ◽  
Vol 16 (12) ◽  
pp. 124024
Author(s):  
Lauren A MacDonald ◽  
Kevin W Turner ◽  
Ian McDonald ◽  
Mitchell L Kay ◽  
Roland I Hall ◽  
...  
Keyword(s):  
Isotope Composition ◽  
Monitoring Program ◽  
Additive Models ◽  
Water Levels ◽  
Wildlife Habitat ◽  
Ecosystem Monitoring ◽  
International Polar Year ◽  
Monitoring Programs ◽  
Old Crow Flats

Abstract Lake-rich northern permafrost landscapes are sensitive to changing climate conditions, but ability to track real-time and potentially multiple hydrological responses (e.g. lake expansion, drawdown, drainage) is challenging due to absence of long-term, sustainable monitoring programs in these remote locations. Old Crow Flats (OCF), Yukon, is a Ramsar Wetland of International Importance where concerns about low water levels and their consequences for wildlife habitat and traditional ways of life prompted multidisciplinary studies during the International Polar Year (2007–2008) and led to the establishment of an aquatic ecosystem monitoring program. Here, we report water isotope data from 14 representative thermokarst lakes in OCF, the foundation of the monitoring program, and time-series of derived metrics including the isotope composition of input waters and evaporation-to-inflow ratios for a 13 year period (2007–2019). Although the lakes spanned multiple hydrological categories (i.e. rainfall-, snowmelt- and evaporation-dominated) based on initial surveys, well-defined trends from application of generalized additive models and meteorological records reveal that lakes have become increasingly influenced by rainfall, and potentially waters from thawing permafrost. These sources of input have led to more positive lake water balances. Given the documented role of rainfall in causing thermokarst lake drainage events in OCF and elsewhere, we anticipate increased vulnerability of lateral water export from OCF. This study demonstrates the value of long-term isotope-based monitoring programs for identifying hydrological consequences of climate change in lake-rich permafrost landscapes.

scholarly journals Influence of Tillage on the Mollisols Physicochemical Properties, Seed Emergence and Yield of Maize in Northeast China

Agriculture ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 939
Author(s):  
Qiang Chen ◽  
Xingyi Zhang ◽  
Li Sun ◽  
Jianhua Ren ◽  
Yaru Yuan ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Physicochemical Properties ◽  
Northeast China ◽  
Soil Structure ◽  
Aggregate Stability ◽  
Maize Yield ◽  
Conventional Tillage ◽  
Soil Conditions ◽  
Emergence Period

Tillage practices are critical for sustaining soil quality necessary for successful crop growth and productivity, but there are only few studies for strip tillage (ST) in the Mollisols region of Northeast China at present. A long-term (≥10-year) study was carried out to investigate the influence of within the tilled row (IR) and between rows (BR) in ST (10-year), conventional tillage (CT, 14-year) and no tillage (NT, 14-year) treatments on soil physicochemical properties. Soil samples were taken in May of 2019 at 0–5, 5–10, 10–20 and 20–30 cm depths and used to analyze bulk density (BD), soil aggregate distribution and stability, and soil organic carbon (SOC). Meanwhile, our study also explored the differences in seed emergence, soil moisture, and temperature during the seed emergence period, and yield of maize (Zea mays L.) among the different treatments. Similar soil properties were observed between ST-BR and NT, which showed they had a significantly greater BD, >0.25 mm water stable aggregate content (WR0.25) (especially in the amount of >2 mm and 1–2 mm size proportion), aggregate stability, and SOC than ST-IR and CT-IR at a depth of 0–20 cm. By improving soil conditions of seedbed, ST-IR and CT-IR increased soil temperature above NT by 1.64 °C and 1.80 °C, respectively, and ST-IR had a slight greater soil moisture than CT-IR in the top 10 cm layer during the seed emergence period. Late maize seed emergence was observed NT in than ST-IR and CT-IR and the average annual yields in ST were slightly greater than NT and CT, but the differences were not significant. Our results also showed that CT-BR had a poor soil structure and lower SOC than other treatments at 0–30 cm depth. We conclude from these long-term experimental results that ST could improve soil water-heat conditions to promote seed germination, maintain soil structure, and increase the maize yield and it should be applied in the Mollisols region of Northeast China.

scholarly journals Identification of the important environmental factors influencing natural vegetation succession following cropland abandonment on the Loess Plateau, China

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e10349
Author(s):  
Zhenguo Zhang ◽  
Mingming Wang ◽  
Jikai Liu ◽  
Xinwei Li
Keyword(s):  
Loess Plateau ◽  
Correspondence Analysis ◽  
Classification Tree ◽  
Detrended Correspondence Analysis ◽  
Vegetation Succession ◽  
Natural Vegetation ◽  
Vegetation Types ◽  
The Loess Plateau ◽  
Cropland Abandonment

Identification of typical vegetation succession types and their important influencing factors is an important prerequisite to implement differential vegetation and soil management after land abandonment on the Loess Plateau, China. However, there is no reported study specifically on the identification of vegetation types and their important factors as well as the thresholds of the important factors for classification of the vegetation types, based on the medium- to long-term succession of natural vegetation after cropland abandonment. We collected vegetation and soil data on the natural vegetation with the longest 60-year-old forest communities that developed after cropland abandonment and analyzed the data using two-way indicator species analysis, detrended correspondence analysis, direct canonical correspondence analysis and classification tree model. The vegetation communities were classified into five distinct vegetation types, including Artemisia scoparia, Lespedeza davurica and Stipa bungeana, Artemisia giraldii pamp, Sophora viciifolia, Quercus liaotungensis and Biota orientalis. The years after cropland abandonment and soil C/N were further identified as important factors determining the types of vegetation. Likewise, it was observed that most of the investigated soil nutrient variables and soil texture-related variables improved with the vegetation succession while soil water in the surface layers showed a decreasing trend. These findings may provide an ecological basis for site-specific management of vegetation types after cropland abandonment in the medium-long term on the Loess Plateau. Our results encourage further exploration of vegetation succession and their important factors based on longer periods of vegetation succession after cropland abandonment under more soil and climatic conditions on the mountainous areas as the Loess Plateau.

Paleolimnology in Deep Time: The Evolution of Lacustrine Ecosystems

2003 ◽  
Author(s):  
Andrew S. Cohen
Keyword(s):  
Fossil Record ◽  
World Ocean ◽  
Biological Evolution ◽  
Body Distribution ◽  
Freshwater Organisms ◽  
History Of ◽  
Living Organisms ◽  
Lake Basins ◽  
Lake Beds

Most lakes are geologically ephemeral; even the longest-lived individual lakes persist only for tens of millions of years. However there is a continuity to lake systems that transcends the geologically short history of individual lake basins. This continuity comes from the long-term biological evolution of life in freshwater, and fittingly, forms the final subject of this treatment of paleolimnology. Like the oceans, lakes have provided habitats for living organisms for most of the earth’s history. Yet the patterns of aquatic ecosystem evolution in rivers and lakes have differed dramatically from those of the oceans. In large part this can be traced to the fundamentally ephemeral nature of most continental aquatic habitats and the ‘‘disconnectedness’’ in both time and space that exists between individual lakes and rivers compared with the world ocean. This pattern of temporal and spatial patchiness in water body distribution on the continents has shaped the evolution of lacustrine species and communities. Some understanding of this history can be gleaned from the study of modern ecology and molecular genetics of living freshwater organisms. But to understand long-term trends in lacustrine biodiversity and their relationship to the history of the lacustrine environment we must turn to the pre- Quaternary fossil record. Understanding this history, the timing and tempo of major species diversification and extinction events, and the evolution of key ecological innovations is critical for correctly interpreting ancient lake deposits. The fossil record of pre-Quaternary lakes is more difficult to interpret than that of more recent lake basins. Robust phylogenies are largely unavailable for clades of ancient lacustrine fossils, hindering our ability to test hypotheses of evolutionary ecology, although that situation hopefully will improve in coming years. Many major clades of fossil lacustrine organisms are extinct, and ecologies must be inferred from their depositional context. Even for organisms that have close-living relatives, our certainty in making inferences about habitat and relationship with other species weakens as we go back in time. Also the record we have to work with deteriorates with age, the result of (a) a declining volume of lake beds available for study with increasing age, (b) difficulties associated with processing lithified lake beds for their fossil content, and (c) an increasing likelihood of destruction by diagenesis with increasing age.

MAXIMIZING RESTORATION SUCCESS WHEN THE GOOD GROUND IS GONE

2017 ◽  
Vol 12 (3) ◽  
pp. 115-123
Author(s):  
Alex Zimmerman
Keyword(s):  
Management Practices ◽  
Soil Conditions ◽  
Construction Sites ◽  
Repeated Cycle ◽  
Restoration Success ◽  
Fundamental Causes ◽  
Essential Nutrient ◽  
Living Organisms ◽  
Construction Schedules

INTRODUCTION “The good ground is gone” often refers to the challenging nature of construction sites these days. Building on steeper slopes and within tighter boundaries while accelerating construction schedules is adding to the challenge of construction managers. Often the revegetation and restoration is unfortunately not planned or timed for successful long-term vegetation success. Site soil conditions are frequently overlooked and the timing necessary for seed germination, expression, and establishment are rarely factors in determining the schedule of seeding applications for optimum results. All too often less than desired results or failure is the accepted outcome. This will increase the future maintenance costs and encourage the repeated “finger pointing” while seeking to blame one cause or another. Typically, this often-repeated process fails to address the fundamental causes and thereby rarely fixes the problems moving forward. In an effort to break out of this all too often repeated cycle, let's break down the principle challenges and explore options for successful restoration of challenging sites. Successful, long-term revegetation starts with the soil. Without quality soil that takes years to accumulate naturally, revegetation efforts regularly fail or the outcomes are less than ideal. During construction, mining, and general land disturbing activities the soil will be degraded even while practicing the best topsoil harvesting and stock-piling management practices. Many areas where vegetation is desired are essentially mineral without any organic matter or biological activity. When available, stockpiled topsoil will also degrade; the environment within the pile will create conditions that microbes, essential for plant health, will be negatively affected. The longer the stripped soils are stockpiled, the more living organisms are lost. Recommendations and even requirements for limiting the depth of the pile to reduce the loss of beneficial microbes is rarely possible given the tight boundaries of project limits facing site operators. When the stockpile depth is able to be minimized, the pile must also be turned regularly to reduce the loss of the essential nutrient cycling microbiome present in healthy soils.

scholarly journals Long-Term Effect of Manure and Mineral Fertilizer Application Rate on Maize Yield and Accumulated Nutrients Use Efficiencies in North China Plain

Agronomy ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1329
Author(s):  
Fan Fan ◽  
Hongyan Zhang ◽  
Gabriela Alandia ◽  
Laichao Luo ◽  
Zhenling Cui ◽  
...  
Keyword(s):  
North China Plain ◽  
North China ◽  
Smallholder Farmers ◽  
Mineral Fertilizer ◽  
Organic Manure ◽  
Soil Conditions ◽  
Available N ◽  
Fertilizer Application Rate ◽  
Maize Yields

Overuse of mineral fertilizer has become common at the North China Plain. Simultaneously, more organic manure resources are available for smallholder farmers. In order to increase the use of organic manure and reduce mineral fertilizer applications, a 10-year fertilization experiment with maize took place between 2008 and 2017. We assessed the long-term effects of cattle manure (CM) application and a complete nutrient substitution with mineral fertilizer (MF) at four application levels (3, 6, 9 and 12 t ha−1 CM) on yield, macronutrients (N, P and K) use efficiencies and soil conditions. Results showed that maize yields from CM and MF treatments differed across time and were significantly different in the first year of the experiment to no significant differences with increasing experimental time. In addition, increased MF levels did not result in increased maize yields; this response was different with CM applications. The highest 10-year maize average yield was 7.7 t ha−1 obtained with 9 t ha−1 of CM. Our results also showed that at the lowest application level (3 t ha−1 CM), the partial factor productivity (PFP) and the agronomic efficiency (AE) of all macronutrients were significantly higher with MF than with CM applications. Nevertheless, these differences narrowed with increased fertilizer input levels. The MF and CM recovery efficiency (RE) of N, P and K performed differently. Generally, MF exhibited significantly higher N-RE than CM treatments. CM treatments had significantly higher P-RE, but no K-RE differences were found between CM and MF. Soil available N, P and K significantly increased when fertilizer levels raised. MF treatments exhibited similar levels of soil available N, but lower soil available P and K compared with CM treatments.

scholarly journals ARBOREOUS SPECIES POPULATION IN A TOPOGRAPHIC GRADIENT OF MIXED OMBROPHILOUS FOREST IN RIO GRANDE DO SUL

FLORESTA ◽  
2014 ◽  
Vol 44 (4) ◽  
pp. 553
Author(s):  
Igor Da Silva Narvaes ◽  
Solon Jonas Longhi ◽  
Ricardo De Vargas Kilca ◽  
Tales Eduardo Sangoi Rodrigues
Keyword(s):  
Correspondence Analysis ◽  
Canonical Correspondence Analysis ◽  
Rio Grande ◽  
Soil Conditions ◽  
Rio Grande Do Sul ◽  
Analysis Model ◽  
Environmental Preferences ◽  
Species Population ◽  
Ombrophilous Forest

AbstractThis study was part of the Long Term Ecological Project (PELD) conducted in the São Francisco de Paula National Forest, RS where Mixed Ombrophilous Forest is predominant. The aim was to identify distribution of arboreous species depending on different soil conditions occurring in the low, medium and upper slopes of the studied area. 180 sample units of 100 m2 distributed along the topographical gradient were installed, with identification of the totality of arboreous species with 3 cm ≤ CBH < 30 cm and height exceeding 1.30 meters. In addition, thirteen environmental variables were collected in each sub-unit. The Canonical Correspondence Analysis model (CCA) indicated that only the slope, the topographic position, the stoniness and the soil color (up to 50 cm in depth) were the variables that best distinguished the sample groups of the slope environments. Out of the 53 species included in the model, ten species showed best correlations with the typical environments of upper slopes and 12 species were most characteristics of the lower positions, while the remaining resulted well adapted to different hillside topographic conditions. Environmental preferences of the species could be considered in silvicultural and recuperation programs applied to hillside environments of the region.Keywords:  Araucarian Forest; species distribution pattern, edaphic characteristics; canonical correspondence analysis. ResumoOcupação de espécies arbóreas em um gradiente topográfico na Floresta Ombrófila Mista no Rio Grande do Sul. O presente estudo foi parte do Projeto Ecológico de Longa Duração (PELD), realizado na Floresta Nacional de São Francisco de Paula, RS, onde predomina a Floresta Ombrófila Mista. O objetivo foi identificar relações de distribuição das espécies arbóreas em diferentes condições edáficas que ocorrem em posições inferiores, médias e superiores em encostas na área de estudo. Foram instaladas 180 subunidades amostrais de 100 m2 distribuídas ao longo dessas encostas, identificados todos os indivíduos arbóreos com 3 cm ≤ CAP < 30 cm e altura superior a 1,30 metros, além de13 variáveis ambientais inventariadas em cada subunidade. O modelo de Análise de Correspondência Canônica (ACC) indicou que a variação na declividade, na posição topográfica, na pedregosidade e na cor dos solos (na profundidade de até 50 cm) foram as variáveis que melhor distinguiram os grupos de parcelas que caracterizaram os ambientes das encostas. Das 53 espécies inseridas no modelo, dez espécies demonstraram maiores correlações com os ambientes típicos das encostas superiores e 12 espécies foram mais características das posições inferiores, enquanto que as demais apresentaram ampla adaptação às diferentes posições das encostas. As preferências ambientais das espécies poderiam ser consideradas em programas silviculturais e de recuperação nos ambientes de encostas na região.Palavras-chave:  Floresta com Araucária; padrão de distribuição de espécies; características edáficas; análise de correspondência canônica. 

scholarly journals After-effect of long-term soil management on soil respiration and otherqualitative parameters under prolonged dry soil conditions

2015 ◽  
Vol 39 ◽  
pp. 633-651 ◽  
Author(s):  
Dalia FEIZIENE ◽  
Dalia JANUSAUSKAITE ◽  
Virginijus FEIZA ◽  
Agne PUTRAMENTAITE ◽  
Ausra SINKEVICIENE ◽  
...  
Keyword(s):  
Soil Respiration ◽  
Soil Management ◽  
Soil Conditions ◽  
After Effect ◽  
Dry Soil

scholarly journals Can Selection Thinning Convert Even-Age Douglas-Fir Stands to Uneven-Age Structures?

2001 ◽  
Vol 16 (1) ◽  
pp. 35-43 ◽  
Author(s):  
Mark Miller ◽  
Bill Emmingham
Keyword(s):  
Douglas Fir ◽  
Wildlife Habitat ◽  
Good Growth ◽  
Structural Development ◽  
Growing Stock ◽  
Harvest Frequency ◽  
Reconstruction Methods ◽  
Understory Trees ◽  
Long Term Experience

Abstract Uneven-age management of Douglas-fir (Pseudotsuga menziesii) stands can be used to address aesthetic, wildlife habitat, biodiversity, and sustainability concerns, but there has been little long-term experience with this type of management. To develop timely information on converting even-age stands to uneven-age forests, we used retrospective stand reconstruction methods to document harvest frequency, intensity, and stand structural development at four sites in western Oregon. We studied stands managed by selection thinning and identified strategies for creating and managing uneven-age forests. Selection thinning benefited mid- and understory trees and stimulated natural regeneration. Although stand growth was less than expected from low thinning, growth per unit of growing stock was similar to that in unmanaged stands. Douglas-fir often dominated regeneration and had satisfactory vigor at stocking levels about half that considered full stocking for even-age management, but good growth of regeneration may require even lower overstory stocking. Shade-tolerant grand fir and western hemlock, however, were more abundant at higher stocking levels. Selection thinning of young Douglas-fir stands can sometimes be effective in promoting viable regeneration while providing regular income and biodiversity. Because this was a retrospective study only, further, long-term testing is necessary. West. J. Appl. For. 16(1):35–43.

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