scholarly journals Long‐term vegetation changes in Nardus grasslands indicate eutrophication, recovery from acidification, and management change as the main drivers

2020 ◽  
Vol 23 (4) ◽  
pp. 508-521
Author(s):  
Cord Peppler‐Lisbach ◽  
Nils Stanik ◽  
Natali Könitz ◽  
Gert Rosenthal
Keyword(s):  
Vegetation Changes ◽  
Management Change ◽  
Recovery From Acidification

A 1 Ma record of climate-induced vegetation changes using sed aDNA and pollen in a biodiversity hotspot: Lake Towuti, Sulawesi, Indonesia

2021 ◽  
Author(s):  
Akhtar-E Ekram ◽  
Rebecca Hamilton ◽  
Matthew Campbell ◽  
Chloe Plett ◽  
Sureyya Kose ◽  
...  
Keyword(s):  
Relative Abundance ◽  
Carbon Fixation ◽  
Biodiversity Hotspot ◽  
Fossil Pollen ◽  
Vegetation Changes ◽  
Pollen Record ◽  
River Channels ◽  
Sedimentary Record ◽  
Lake Towuti

<p>Several studies have shown that ancient plant-derived DNA can be extracted and sequenced from lake sediments and complement the analysis of fossil pollen in reconstructing past vegetation responses to climate variability and anthropogenic perturbations. The majority of such studies have been performed on Holocene lakes located in cooler higher latitude regions whereas similar studies from tropical lakes are limited. Here, we report a ~1 Ma record of vegetation changes in tropical Lake Towuti (Sulawesi, Indonesia) through parallel pollen and sedimentary ancient DNA (sed aDNA) analysis. Lake Towuti is located in a vegetation biodiversity hotspot and in the centre of the Indo Pacific Warm Pool (IPWP), which comprises the world’s warmest oceanic waters and influences globally important climate systems. In the context of global change, the surface area of the IPWP is rapidly expanding. Lake Towuti is of particular interest since it provides a unique opportunity to obtain a long-term record of IPWP-controlled climate-ecosystem interactions and ecosystem resilience. Stratigraphic analysis of fossil pollen vs. sequencing of preserved chloroplast DNA (cpDNA) signatures (i.e., trnL-P6) both revealed that Lake Towuti experienced significant vegetation changes during the transition from a landscape initially characterized by active river channels, shallow lakes and swamps into a permanent lake ~1 Ma ago. Both proxies marked a predominance of trees or shrubs during most of Lake Towuti’s history, but the trnL-P6 barcoding approach revealed a much higher relative abundance of remote montane conifers, which likely have produced large amounts of chloroplast-rich airborne pollen that were subsequently buried in the sedimentary record. The pollen record showed a higher relative abundance of evergreen tropical forest vegetation, whereas the trnL-P6 record revealed a higher relative abundance of predominantly wetland herbs that must have entered the lake from the local catchment in the form of chloroplast-rich litter. Furthermore, the sedimentary record was rich in presumably wind-derived chloroplast-lacking fern spores, while fern trnL-P6 was only sporadically detected. Only through trnL-P6 barcoding, fern-derived biomass in the sedimentary record could be identified as Schizaeaceae, which is a primitive tropical grass-like fern family often associated with swampy or moist soils. Unlike pollen, trnL-P6 could identify grasses at clade and subfamily levels and confirmed that the majority of grasses in the area represented wet climate C3 grasses or those that can switch between C3 and C4 carbon fixation pathways, whereas grasses that can only perform C4 carbon fixation, indicative of dry climate conditions, were not detected. At least for sediments deposited prior to the Last Glacial Maximum, neither pollen nor trnL-P6 revealed significant vegetation changes between alternating layers of lacustrine green and red sideritic clays thought to have been deposited during orbitally controlled wetter vs. drier periods. These preliminary results suggest that vegetation in this tropical biodiversity hotspot may be relatively resilient to long-term variations in IPWP hydrology.</p>

scholarly journals Land use influences on acidification and recovery of freshwaters in Galloway, south-west Scotland

2001 ◽  
Vol 5 (3) ◽  
pp. 451-458 ◽  
Author(s):  
R. C. Helliwell ◽  
R. C. Ferrier ◽  
L. Johnston ◽  
J. Goodwin ◽  
R. Doughty
Keyword(s):  
Surface Waters ◽  
Chemical Recovery ◽  
Dry Period ◽  
Sulphur Deposition ◽  
South West ◽  
Recovery From Acidification ◽  
Long Term Trends ◽  
Acid Status ◽  
Annual Discharge

Abstract. The long term response of surface waters to changes in sulphur deposition and afforestation is investigated for three upland river systems in the Galloway region of south-west Scotland. From 1984-1999, these rivers exhibited a statistically significant decline in non-marine sulphate concentrations in response to reduced acid deposition. This reduction in non-marine sulphate was, however, insufficient to induce a pH recovery over the period. A statistically significant increase in river pH was observed between 1956-1970 (0.05 yr-1) when subsidised agricultural lime payments were at a maximum. In 1976, this subsidy ceased and surface waters have progressively acidified. In addition, climatic change is found to influence long-term trends in pH. Mean annual pH was greatest during a dry period between 1969-1973 when total annual discharge was low. Thereafter, pH declined gradually in response to higher rainfall and increased total annual discharge. Overall, surface waters draining the afforested catchments of the Rivers Cree and Bladnoch are more acid than those draining the moorland catchment of the Luce. These results indicate that in afforested catchments, current reductions in sulphur emissions have not led to an observed improvement in the acid status of surface waters. Forestry, therefore, represents a confounding factor with regard to chemical recovery from acidification in this region. Keywords: acidification, afforestation, deposition, rivers, lochs, non-marine sulphate, pH

scholarly journals Decoupled trophic responses to long‐term recovery from acidification and associated browning in lakes

2019 ◽  
Vol 25 (5) ◽  
pp. 1779-1792 ◽  
Author(s):  
Taylor H. Leach ◽  
Luke A. Winslow ◽  
Nicole M. Hayes ◽  
Kevin C. Rose
Keyword(s):  
Recovery From Acidification ◽  
Trophic Responses

Historical forest survey data from Eucalyptus - Callitris forests: a valuable resource for long-term vegetation studies

2009 ◽  
Vol 57 (7) ◽  
pp. 541 ◽  
Author(s):  
Robyn K. Whipp ◽  
Ian D. Lunt ◽  
Andrew Deane ◽  
Peter G. Spooner
Keyword(s):  
Survey Data ◽  
Survey Methods ◽  
Quantitative Information ◽  
Data Sources ◽  
Stem Density ◽  
Vegetation Changes ◽  
Management Interventions ◽  
Eastern Australia ◽  
Historical Forest

Quantitative information about historical changes in natural ecosystems is important for guiding management interventions. However, few accurate data sources are available for documenting long-term vegetation changes. In this paper, we describe a neglected source of quantitative information on historical forest structure: forest inventory strip surveys, which were widely used in eastern Australia from 1915 to the 1940s. Strip surveys provide quantitative information on the species composition, stem density, basal area, stem form and size class distributions of dominant tree species. Such information is not available from other widespread data sources. Strip surveys usually surveyed 10% of the total forest area. In this paper, we describe the original survey methods, demonstrate how to decode data-book entries, and analyse a sample dataset from the Pilliga State Forests in northern New South Wales to illustrate the information that can be obtained from this material. Strip survey data-books are poorly archived. Many books exist for Eucalyptus–Callitris forests in northern and central NSW, and additional books may exist for many other forest types in eastern Australia. Strip surveys provide a valuable data source for studying long-term vegetation changes in forest ecosystems. We urge forest managers to search for and preserve this precious archival material.

scholarly journals Recovery from acidification of lochs in Galloway, south-west Scotland, UK: 1979-1998

2001 ◽  
Vol 5 (3) ◽  
pp. 421-432 ◽  
Author(s):  
R. C. Ferrier ◽  
R. C. Helliwell ◽  
B. J. Cosby ◽  
A. Jenkins ◽  
R. F. Wright
Keyword(s):  
General Pattern ◽  
Base Cations ◽  
Rapid Decline ◽  
Sea Salts ◽  
South West ◽  
Acid Neutralising Capacity ◽  
Sulphate Deposition ◽  
Recovery From Acidification ◽  
Chloride Concentrations

Abstract. The Galloway region of south-west Scotland has historically been subject to long-term deposition of acidic precipitation which has resulted in acidification of soils and surface waters and subsequent damage to aquatic ecology. Since the end of the 1970s, however, acidic deposition has decreased substantially. The general pattern is for a rapid decline in non-marine sulphate in rainwater over the period 1978-1988 followed by stable concentrations to the mid-1990s. Concentrations of nitrate and ammonium in deposition have remained constant between 1980 and 1998. Seven water quality surveys of 48 lochs in the Galloway region have been conducted between 1979 and 1998. During the first 10 years, from 1979, there was a major decline in regional sulphate concentrations in the lochs, which was expected to have produced a decline in base cations and an increase in the acid neutralising capacity. But sea-salt levels (as indicated by chloride concentrations) were approximately 25% higher in 1988 than in 1979 and thus short-term acidification due to sea-salts offset much of the long-term recovery trend expected in the lochs. During the next 10 years, however, the chloride concentrations returned to 1979 levels and the lochs showed large increases in acid neutralising capacity despite little change in sulphate concentrations. From the observed decline in sulphate deposition and concentrations of sulphate in the lochs, it appears that approximately 75% of the possible improvement in acid neutralising capacity has already occurred over the 20-year period (1979-1998). The role of acid deposition as a driving factor for change in water chemistry in the Galloway lochs is confounded by concurrent changes in other driving variables, most notably, factors related to episodic and year-to-year variations in climate. In addition to inputs of sea-salts, climate probably also influences other chemical signals such as peaks in regional nitrate concentrations and the sharp increase in dissolved organic carbon during the 1990s. Keywords: acidification, recovery, Galloway, sulphur, nitrogen

scholarly journals Conserving the endemic birds on the Comoro Islands, II: population fluctuations on Ngazidja

1992 ◽  
Vol 2 (1) ◽  
pp. 81-91 ◽  
Author(s):  
Jan Stevens ◽  
Marc Herremans ◽  
Michel Louette
Keyword(s):  
Vegetation Changes ◽  
Population Fluctuations ◽  
Population Changes ◽  
Point Counts ◽  
Shrub Layer ◽  
Forest Exploitation ◽  
Endemic Birds ◽  
Land Bird ◽  
Comoro Islands

SummaryLand bird abundances on Ngazidja, Comoro Islands, obtained by point counts in September 1985 and November–December 1989 are compared. The overall abundance of most species did not differ significantly. Most differences can be interpreted as normal within-year fluctuations. Some important changes are identified and attributed to shortterm vegetation changes: increase of Columba polleni, Coracopsis vasa, Zoonavena grandidieri, Coracina cinerea in Nioumbadjou after abandonment of forest exploitation; decrease of Coracina cinerea at M'Lima Mani North after replacement of the natural shrub layer by bananas. Genuine long-term population changes occur in Coracopsis nigra (increase) and Corvus albus (decrease).

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