The impact of 36 years of grazing management on vegetation dynamics in dune slacks

2013 ◽  
Vol 50 (6) ◽  
pp. 1367-1376 ◽  
Author(s):  
Jonathan Millett ◽  
Sally Edmondson
2012 ◽  
Vol 12 (10) ◽  
pp. 3123-3137 ◽  
Author(s):  
C. M. Gouveia ◽  
A. Bastos ◽  
R. M. Trigo ◽  
C. C. DaCamara

Abstract. The present work aims to study the combined effect of drought and large wildfires in the Iberian Peninsula relying on remotely sensed data of vegetation dynamics and leaf moisture content, in particular monthly NDVI, NDWI and NDDI time series from 1999–2009, derived from VEGETATION dataset. The impact of the exceptional 2004/2005 drought on vegetation was assessed for vegetation recovering from the extraordinary fire season of 2003 and on the conditions that contributed to the onsetting of the fire season of 2005. Drought severity was estimated by the cumulative negative effect on photosynthetic activity (NDVI) and vegetation dryness (NDDI), with about 2/3 of Iberian Peninsula presenting vegetative stress and low water availability conditions, in spring and early summer of 2005. Furthermore, NDDI has shown to be very useful to assess drought, since it combines information on vegetation and water conditions. Moreover, we show that besides looking at the inter-annual variability of NDVI and NDDI, it is useful to evaluate intra-annual changes (δNDVI and δNDDI), as indicators of change in vegetation greenness, allowing a detailed picture of the ability of the different land-cover types to resist to short-term dry conditions. In order to assess drought impact on post-fire regeneration, recovery times were evaluated by a mono-parametric model based on NDVI data and values corresponding to drought months were set to no value. Drought has shown to delay recovery times for several months in all the selected scars from 2003. The analysis of vegetation dynamics and fire selectivity in 2005 suggests that fires tended to occur in pixels presenting lower vegetative and water stress conditions during spring and early summer months. Additionally, pre-fire vegetation dynamics, in particular vegetation density and water availability during spring and early summer, has shown to influence significantly the levels of fire damage. These results stress the role of fuel availability in fire occurrence and impact on the Iberian Peninsula.


2016 ◽  
Vol 44 (1) ◽  
pp. 66-73 ◽  
Author(s):  
EMMA L. GREEN ◽  
FELIX EIGENBROD ◽  
KATE SCHRECKENBERG ◽  
SIMON WILLCOCK

SUMMARYMiombo woodlands supply ecosystem services to support livelihoods in southern Africa, however, rapid deforestation has necessitated greater knowledge of tree growth and off-take rates to understand the sustainability of miombo exploitation. We established 48 tree inventory plots within four villages in southern Malawi, interviewed representatives in these same villages about tree management practices and investigated the impact of climate on vegetation dynamics in the region using the ecosystem modelling framework LPJ-GUESS. Combining our data with the forest yield model MYRLIN revealed considerable variation in growth rates across different land uses; forested lands showed the highest growth rates (1639 [95% confidence interval 1594–1684] kg ha–1 year–1), followed by settlement areas (1453 [95% confidence interval 1376–1530] kg ha–1 year–1). Based on the modelled MYRLIN results, we found that 50% of the villages had insufficient growth rates to meet estimated off-take. Furthermore, the results from LPJ-GUESS indicated that sustainable off-take approaches zero in drought years. Local people have recognized the unsustainable use of natural resources and have begun planting activities in order to ensure that ecosystem services derived from miombo woodlands are available for future generations. Future models should incorporate the impacts of human disturbance and climatic variation on vegetation dynamics; such models should be used to support the development and implementation of sustainable forest management.


2021 ◽  
Author(s):  
Laura Dziomber ◽  
Lisa Gurtner ◽  
Maria Leunda ◽  
Christoph Schwörer

<p>Current and future climate change is a serious threat to biodiversity and ecosystem stability. With a rapid increase of global temperatures by 1.5°C since the pre-industrial period and a projected warming of 1.5-4°C by the end of this century, plant species are forced to either adapt to these changes, shift their distribution range to higher elevation, or face population decline and extinction. Today, there is an urgent need to better understand the responses of mountain vegetation to climate change in order to predict the consequences of the human-driven global change currently occurring during the Anthropocene and maintain species diversity and ecosystem services. However, most predictions are based on short-term experiments. There is, in general, an insufficient use of longer time scales in conservation biology to understand long-term processes. Palaeoecological data are a great source of information to infer past species responses to changing environmental factors, such as climate or anthropogenic disturbances.</p><p>The last climate change of a similar magnitude and rate as projected for this century was the transition between the last Ice Age and the Holocene interglacial (ca. 11,700 years ago). By analyzing subfossil plant remains such as plant macrofossils, charcoal and pollen from natural archives, we can study past responses to climate change. However, until recently it was not possible to reconstruct changes at the population level. With the development of new methods to extract ancient DNA (aDNA) from plant remains and next generation DNA-sequencing techniques, we can now infer past population dynamics by analyzing the genetic variation through time. Ancient DNA might also be able to reveal if species could adapt to climatic changes by identifying intraspecific variation of specific genes related to climatic adaptations.</p><p>We are currently investigating a palaeoecological archive from a high-altitude mountain lake, Lai da Vons (1991 m a.s.l), situated in Eastern Switzerland. We are presenting preliminary macrofossil, pollen and charcoal results to reconstruct local to regional vegetation and fire dynamics with high chronological precision and resolution. In a next step, we will use novel molecular methods, in order to track adaptive and neutral genetic diversity through the Holocene by analyzing aDNA from subfossil conifer needles. The overarching goal of this large-scale, multiproxy study is to better understand past vegetation dynamics and the impact of future climate change on plants at multiple scales; from the genetic to the community level.</p><p> </p>


2019 ◽  
Vol 41 (6) ◽  
pp. 535 ◽  
Author(s):  
C. M. Waters ◽  
S. E. McDonald ◽  
J. Reseigh ◽  
R. Grant ◽  
D. G. Burnside

Demonstrating sustainable land management (SLM) requires an understanding of the linkages between grazing management and environmental stewardship. Grazing management practices that incorporate strategic periods of rest are promoted internationally as best practice. However, spatial and temporal trends in unmanaged feral (goat) and native (kangaroo) populations in the southern Australian rangelands can result land managers having, at times, control over less than half the grazing pressure, precluding the ability to rest pastures. Few empirical studies have examined the impacts of total grazing pressure (TGP) on biodiversity and resource condition, while the inability to manage grazing intensity at critical times may result in negative impacts on ground cover, changes in pasture species composition, increased rates of soil loss and reduce the ability for soils to store carbon. The widespread adoption of TGP control through exclusion fencing in the southern Australian rangelands has created unprecedented opportunities to manage total grazing pressure, although there is little direct evidence that this infrastructure leads to more sustainable land management. Here we identify several key indicators that are either outcome- or activity-based that could serve as a basis for verification of the impacts of TGP management. Since TGP is the basic determinant of the impact of herbivory on vegetation it follows that the ability for rangeland pastoral management to demonstrate SLM and environmental stewardship will rely on using evidence-based indicators to support environmental social licence to operate.


2019 ◽  
Vol 12 (1) ◽  
pp. 179-193 ◽  
Author(s):  
Chantelle Burton ◽  
Richard Betts ◽  
Manoel Cardoso ◽  
Ted R. Feldpausch ◽  
Anna Harper ◽  
...  

Abstract. Disturbance of vegetation is a critical component of land cover, but is generally poorly constrained in land surface and carbon cycle models. In particular, land-use change and fire can be treated as large-scale disturbances without full representation of their underlying complexities and interactions. Here we describe developments to the land surface model JULES (Joint UK Land Environment Simulator) to represent land-use change and fire as distinct processes which interact with simulated vegetation dynamics. We couple the fire model INFERNO (INteractive Fire and Emission algoRithm for Natural envirOnments) to dynamic vegetation within JULES and use the HYDE (History Database of the Global Environment) land cover dataset to analyse the impact of land-use change on the simulation of present day vegetation. We evaluate the inclusion of land use and fire disturbance against standard benchmarks. Using the Manhattan metric, results show improved simulation of vegetation cover across all observed datasets. Overall, disturbance improves the simulation of vegetation cover by 35 % compared to vegetation continuous field (VCF) observations from MODIS and 13 % compared to the Climate Change Initiative (CCI) from the ESA. Biases in grass extent are reduced from −66 % to 13 %. Total woody cover improves by 55 % compared to VCF and 20 % compared to CCI from a reduction in forest extent in the tropics, although simulated tree cover is now too sparse in some areas. Explicitly modelling fire and land use generally decreases tree and shrub cover and increases grasses. The results show that the disturbances provide important contributions to the realistic modelling of vegetation on a global scale, although in some areas fire and land use together result in too much disturbance. This work provides a substantial contribution towards representing the full complexity and interactions between land-use change and fire that could be used in Earth system models.


PLoS ONE ◽  
2016 ◽  
Vol 11 (4) ◽  
pp. e0152883 ◽  
Author(s):  
G. C. Hurtt ◽  
R. Q. Thomas ◽  
J. P. Fisk ◽  
R. O. Dubayah ◽  
S. L. Sheldon

2020 ◽  
Vol 14 (12) ◽  
pp. 4653-4673
Author(s):  
Lianyu Yu ◽  
Simone Fatichi ◽  
Yijian Zeng ◽  
Zhongbo Su

Abstract. The vadose zone is a zone sensitive to environmental changes and exerts a crucial control in ecosystem functioning and even more so in cold regions considering the rapid change in seasonally frozen ground under climate warming. While the way in representing the underlying physical process of the vadose zone differs among models, the effect of such differences on ecosystem functioning and its ecohydrological response to freeze–thaw cycles are seldom reported. Here, the detailed vadose zone process model STEMMUS (Simultaneous Transfer of Energy, Mass and Momentum in Unsaturated Soil) was coupled with the ecohydrological model Tethys–Chloris (T&C) to investigate the role of influential physical processes during freeze–thaw cycles. The physical representation is increased from using T&C coupling without STEMMUS enabling the simultaneous mass and energy transfer in the soil system (liquid, vapor, ice) – and with explicit consideration of the impact of soil ice content on energy and water transfer properties – to using T&C coupling with it. We tested model performance with the aid of a comprehensive observation dataset collected at a typical meadow ecosystem on the Tibetan Plateau. Results indicated that (i) explicitly considering the frozen soil process significantly improved the soil moisture/temperature profile simulations and facilitated our understanding of the water transfer processes within the soil–plant–atmosphere continuum; (ii) the difference among various representations of vadose zone physics have an impact on the vegetation dynamics mainly at the beginning of the growing season; and (iii) models with different vadose zone physics can predict similar interannual vegetation dynamics, as well as energy, water, and carbon exchanges, at the land surface. This research highlights the important role of vadose zone physics for ecosystem functioning in cold regions and can support the development and application of future Earth system models.


2013 ◽  
Vol 53 (8) ◽  
pp. 856 ◽  
Author(s):  
T. Coventry ◽  
H. Sutherland ◽  
M. Waters ◽  
P. Dutton ◽  
B. Gream ◽  
...  

The Cicerone Project began as a producer-led partnership that sought, over a period of 8 years, to enhance the profitability and sustainability of livestock enterprises by improving the connection between those producers, research and extension. Following a detailed survey, the research and extension needs of livestock producers were identified and several applied investigations were conducted to meet those needs and delivered through a range of extension activities. This final paper of the Cicerone Special Issue reflects on the entire Project from a wide array of perspectives, including livestock producers, researchers, extension specialists and staff employed by the Project, all of whom are authors of this paper. A notable early successful outcome of the Project was the improved precision of footrot diagnosis, which has been of value to the entire sheep industry, and that flowed from a field investigation of benign and virulent footrot combined with detailed genetic investigations, which led to an improved testing regime. This paper also reflects on the findings of an unreplicated agricultural ecosystem research trial, which measured the impact of pasture renovation, increased soil fertility and grazing management on the profitability and sustainability of three different 53-ha farmlets. Valuable findings from this whole-farmlet trial included the need for a high quality feed supply for increasing stocking rate and animal liveweights; the ability and utility of satellite imagery to detect changes in pasture growth, composition and recent grazing pressure; the value of short grazing and long rest periods for controlling Barber’s pole worms of sheep; the impact of increased stocking rates on whole-farm profitability and risk; methods of optimising decisions relating to pasture renovation, fertiliser applications and grazing management; and an integrated analysis of all key measured components of the farmlet management systems. Collectively, these findings were powerful as they were demonstrated at a scale credible to livestock producers using the ‘compare – measure – learn – adopt’ approach, which was the key philosophy adopted by the Cicerone Project. By comparing and measuring different whole-farm systems, and by ensuring that producers had ownership of the trial process, the Project successfully delivered objective findings that producers trusted and which increased our understanding of important drivers of complex grazing enterprises under variable climatic conditions. Some of these drivers included: the influence of soil phosphorus on botanical composition and subsequent livestock production, the role of pasture renovation and soil fertility on herbage supply, herbage quality and stocking rate, and the improved gastrointestinal nematode control delivered by intensive rotational grazing. The beneficiaries of the Project included the 180 farmer members who participated in some 61 field days and workshops; the research and extension collaborators including four postgraduates who completed their research investigations in conjunction with the Project; and some 500 undergraduate and 300 technical students who benefited from coming to understand the applied field comparisons of the three whole-farmlet systems. Having livestock producers play a significant leadership role led to valuable outcomes achieved with research collaborators; this should encourage the development of other learning partnerships which aim to explore complex farming system issues.


Forests ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 1071 ◽  
Author(s):  
Xian Zhu ◽  
Hong S. He ◽  
Shuoxin Zhang ◽  
William D. Dijak ◽  
Yuanyuan Fu

The interactive effects of climatic factors (precipitation and temperature) on vegetation growth can be characterized by their effect on vegetation seasonal dynamics. The interactive effects, seasonal trend of vegetation growth, and its future consistency (potential for future trend) have not been adequately studied in the literature. In this work, using the Enhanced Vegetation Index (EVI) and gridded climate data at a resolution of 250 m in the central Loess Plateau region, we examined seasonal vegetation dynamics with climate changes and the interactive effects of climatic factors on vegetation growth at the pixel and regional scales from the period 2000 to 2015. Vegetation cover in the Central Loess Plateau in China has dramatically changed due to the Grain-for-Green (GFG) ecological restoration program, which was designed to convert cropland to forestland or grassland since 1999. Our results show that the EVI increased significantly during the 16 year period and is likely to continue to increase in the near future. Relatively small Hurst exponents for forestland suggests that the potential for a future increased trend will be weak for the forest. Large Hurst exponents for grassland indicate its strong potential of further increase. Significant increases in spring precipitation have promoted vegetation growth, while significant decreases in summer temperature have had negative effects on vegetation growth. For temperatures between 10 to 20 °C, the impact of temperature on vegetation growth has a clear positive relationship with the moderator variable precipitation. For precipitation < 200 mm in the growing season, the impact of precipitation on vegetation growth has a clearly positive relationship with the moderator variable temperature. Results of this study will provide useful and important guidelines for designing forestland and grassland restoration plans in arid, semiarid and sub-humid regions.


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