scholarly journals Carbon and ecohydrological priorities in managing woody encroachment: An UAV perspective 63 years after a control treatment

2021 ◽  
Author(s):  
Temuulen Tsagaan Sankey ◽  
Jackson Leonard ◽  
Margaret M. Moore ◽  
Joel B Sankey ◽  
Adam Belmonte
Keyword(s):  
Woody Species ◽  
Carbon Accumulation ◽  
Woody Encroachment ◽  
Control Treatment ◽  
Water Yield ◽  
Historical Records ◽  
Aboveground Carbon ◽  
Herbicide Treatment ◽  
Before And After ◽  
Woody Cover

Abstract Woody encroachment, including both woody species expansion and density increase, is a globally observed phenomenon that deteriorates arid and semi-arid rangeland health, biodiversity, and ecosystem services. Mechanical and chemical control treatments are commonly performed to reduce woody cover and restore ecohydrologic function. While the immediate impacts of woody control treatments are well documented in short-term studies, treatment impacts at decadal scales are not commonly studied. Using a controlled herbicide treatment from 1954 in the Sierra Ancha Experimental Forest in central Arizona, USA, we quantify woody encroachment and associated aboveground carbon accumulation in treated and untreated watersheds. Woody encroachment and aboveground carbon are estimated using high resolution multispectral images and photogrammetric data from a fixed-wing unmanned aerial vehicle (UAV). We then combine the contemporary UAV image-derived estimates with historical records from immediately before and after the treatment to consider long-term trends in woody vegetation cover, aboveground carbon, water yield, and sedimentation. Our results indicate that the treatment has had a lasting impact. More than six decades later, woody cover in two treated watersheds are still significantly lower compared to two control watersheds, even though woody cover increased in all four drainages. Aboveground woody carbon in the treated watersheds is approximately one half that accumulated in the control watersheds. The historical records indicate that herbicide treatment also increased water yield and reduced annual sedimentation. Given the sustained reduction in woody cover and aboveground woody biomass in treated watersheds, we infer that the herbicide treatment has had similarly long lasting impacts on ecohydrological function. Land managers can consider legacy impacts from control treatments to better balance carbon and ecohydrological consequences of woody encroachment and treatment activities.

The response of pygmy bluetongue lizards to simulated grazing in the field during three drought years

2012 ◽  
Vol 39 (6) ◽  
pp. 540 ◽  
Author(s):  
Melissa Pettigrew ◽  
C. Michael Bull
Keyword(s):  
Prey Availability ◽  
Careful Consideration ◽  
Grazing Management ◽  
Control Treatment ◽  
Ground Vegetation ◽  
Control Group ◽  
Drought Period ◽  
Before And After ◽  
Simulated Grazing ◽  
Complex Relationships

Context Grazing by domestic stock can directly influence and shape the functions of an ecosystem. Most remaining remnant native grasslands in Australia are under some form of grazing management, with some possible adverse impacts for endemic grassland biota. For the endangered pygmy bluetongue lizard (Tiliqua adelaidensis), grazing of its remnant native grassland habitat has been seen as a potential conservation threat. Aim We aimed to investigate whether lizards altered their basking and foraging behaviour as a response to simulated grazing of the grassland habitat surrounding their burrows. Methods We used field manipulations over 3 years event by manually removing above-ground vegetation in 1 m2 around occupied lizard burrows, to simulate intense grazing events. We video-recorded lizard responses to these manipulations. We filmed lizards before and after the simulated grazing event and monitored basking and foraging response. We also simultaneously filmed a control group of lizards that were not exposed to a simulated grazing event. Key results Although overall time spent basking did not differ between treatment and control groups, the lizards spent more of their basking time completely emerged (bold basking) in the grazing treatment, suggesting they changed behaviour after simulated grazing. Perhaps they were more confident of evading predators that they could more clearly see approaching. In one season lizards made more attempts to catch prey in the grazed treatment than in a control treatment following the treatment, suggesting that grazing might enhance visibility for the ambush predation method that these lizards use. Conclusions The results suggest that grazing may produce some benefits for lizards already established in burrows. This contrasts with some previous results and suggests that management of grazing regimes requires careful consideration of the conditions currently prevalent. In this case, the study was conducted during a drought period, and different results might have emerged in higher rainfall years. Implications Grazing management for lizard conservation requires detailed understanding of the complex relationships among lizard behaviour, vegetation cover and invertebrate prey availability.

scholarly journals History, observation and mathematical models in the seismic analysis of the Valadier abutment area in the Colosseum

1995 ◽  
Vol 38 (5-6) ◽  
Author(s):  
G. Croci ◽  
D. D'Ayala ◽  
R. Liburdi
Keyword(s):  
Mathematical Models ◽  
Seismic Analysis ◽  
Numerical Models ◽  
Time History ◽  
Historical Records ◽  
Direct Integration ◽  
Structural Behaviour ◽  
Seismic Behaviour ◽  
Before And After ◽  
Xix Century

The present work aimed to outline the need to investigate different fields of research to interpret the structural behaviour of a monument as complex as the Colosseum. It is shown how defining the numerical models first. then refining them, followed by interpretation of results. is strictly linked with the inforination gathered from historical records and observation of the ~nonumenta s it is today. The study is confined to the area of the Valadier abutment. analysing its state and its seismic behaviour before and after the XIX century restoration using different ilumerical tools, from the elastic modal analysis to the non linear step by step time history direct integration. The procedure comparati\ely evaluates the reliability in the interpretation of the results and identifies future lines or research.

scholarly journals Woody encroachment over 70 years in South African savannahs: overgrazing, global change or extinction aftershock?

2016 ◽  
Vol 371 (1703) ◽  
pp. 20150437 ◽  
Author(s):  
Nicola Stevens ◽  
B. F. N. Erasmus ◽  
S. Archibald ◽  
W. J. Bond
Keyword(s):  
Land Use ◽  
South African ◽  
Woody Encroachment ◽  
Land Uses ◽  
Conservation Areas ◽  
Rainfall Gradient ◽  
Object Based Image Analysis ◽  
Global Factor ◽  
Object Based ◽  
Woody Cover

Woody encroachment in ‘open’ biomes like grasslands and savannahs is occurring globally. Both local and global drivers, including elevated CO 2 , have been implicated in these increases. The relative importance of different processes is unresolved as there are few multi-site, multi-land-use evaluations of woody plant encroachment. We measured 70 years of woody cover changes over a 1020 km 2 area covering four land uses (commercial ranching, conservation with elephants, conservation without elephants and communal rangelands) across a rainfall gradient in South African savannahs. Different directions of woody cover change would be expected for each different land use, unless a global factor is causing the increases. Woody cover change was measured between 1940 and 2010 using the aerial photo record. Detection of woody cover from each aerial photograph was automated using eCognitions' Object-based image analysis (OBIA). Woody cover doubled in all land uses across the rainfall gradient, except in conservation areas with elephants in low-rainfall savannahs. Woody cover in 2010 in low-rainfall savannahs frequently exceeded the maximum woody cover threshold predicted for African savannahs. The results indicate that a global factor, of which elevated CO 2 is the likely candidate, may be driving encroachment. Elephants in low-rainfall savannahs prevent encroachment and localized megafaunal extinction is a probable additional cause of encroachment. This article is part of the themed issue ‘Tropical grassy biomes: linking ecology, human use and conservation’.

scholarly journals Influence of Plantation Establishment on Discharge Characteristics in a Small Catchment of Tropical Forest

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Siti Aisah Shamsuddin ◽  
Zulkifli Yusop ◽  
Shoji Noguchi
Keyword(s):  
Water Yield ◽  
Plantation Establishment ◽  
Forest Plantation ◽  
Small Catchment ◽  
Forested Catchment ◽  
Clear Cut ◽  
Clear Cutting ◽  
Before And After ◽  
Hopea Odorata ◽  
The Impact

A study was conducted on the impact of forest clearance on discharge from newly established Hopea odorata plantations catchment (14.4 ha). The stands were two years old when this study commenced in year 2006 and the data collection was carried out for two years. The forested catchment (C3) was clear-cut during the preparation of the forest plantation and catchment C1 was left undisturbed. Discharge and rainfall were measured continuously for two years. The discharge measured from years 1997 to 2003 was used also to determine the water yield before and after forest clear-cut. This study showed that the plantation catchment is more responsive to storm with higher total water yield than in the forested catchment. The effect of forest clear cutting to discharge was clearly shown by the increment in the amount following the clear-cut activities and time taken for the recovery of the discharge back to its original state was almost three years. The peak discharge in C3 also was affected in which the biggest change was obtained during the forest clear-cutting period compared with during calibration and after clearing periods. This study is useful as basis for improving the existing guidelines on forest plantation establishment.

scholarly journals Varroacide Effectiveness of Polyvar Yellow® (Flumethrin 275 mg) Preparation

2021 ◽  
Vol 65 (1) ◽  
pp. 189-193
Author(s):  
Beata Bąk ◽  
Jerzy Wilde ◽  
Maciej Siuda ◽  
Jakub Wilk
Keyword(s):  
Treatment Group ◽  
Oxalic Acid ◽  
Varroa Destructor ◽  
Oxalic Acid Solution ◽  
Control Treatment ◽  
Control Group ◽  
North Eastern ◽  
Before And After ◽  
Bee Colonies ◽  
Veterinary Product

Abstract The aim of the experiment was to check the effectiveness of the varroacide veterinary product called PolyVar Yellow® (flumethrin 275 mg) in field conditions in the area of north-eastern Poland. The experiment was carried out on twenty bee colonies, of which in ten (group PY) were tested with the veterinary product and the remaining ten constituted a control group without anti-varroosis treatment (group C). Treatment began in mid-August and lasted until the end of October when bee flights ceased. A control treatment was then conducted with a 3.2% oxalic acid solution. The effectiveness of Varroacide of PolyVar Yellow® was estimated on the basis of the parasite falls on the Varroa sticky inserts and based on the infestation rate of bees with the parasite before and after the treatment. High varroacide effectiveness of the preparation was obtained at 97%. The tested veterinary product was shown to protect effectively bee colonies against reinvasion of Varroa destructor mites.

scholarly journals FORESTRY RESTORATION IN ABANDONED PASTURES OF Urochloa BY DIFFERENT SIZES OF BRUSHWOOD

CERNE ◽  
2017 ◽  
Vol 23 (1) ◽  
pp. 85-94 ◽  
Author(s):  
Rosimeri de Oliveira Fragoso ◽  
Antonio Aparecido Carpanezzi ◽  
Katia Christina Zuffellato- Ribas ◽  
Henrique Soares Koehler
Keyword(s):  
Natural Regeneration ◽  
Native Species ◽  
Woody Species ◽  
Minimum Size ◽  
Control Treatment ◽  
Plant Residues ◽  
Native Plant ◽  
Safe Sites ◽  
Minimum Width ◽  
And Control

ABSTRACT The brushwood is a technique of environmental complexation, which consists in the use of plant residues. This technique, when well established technically, can exert influence on seedbed quality, fostering native plant establishment and ecosystem restoration. In this way, we aimed to evaluate the efficiency of brushwood for the induction of natural regeneration of native species in an area covered by exotic inhibitory grasses of the genus Urochloa, as well as check the minimum size required to prevent the re-invasion of the forage. As a hypothesis, we adopted the minimum width of 4 m as sufficient for the establishment of natural regeneration prior to the reoccupation of grasses. The experiment was conducted between May 2014 and May 2016 in Morretes-PR in a lowland evergreen rain forest area. Seven different sizes of brushwood were compared: 6 x 1, 6 x 2, 6 x 3, 6 x 4, 6 x 5, 6 x 6 m and control treatment. Woody species were identified and counted and herbaceous cover percentage estimated after 4, 8, 12, 18 and 24 months. There was no resumption of natural succession of native species. At any size, brushwood alone was ineffective to prevent the growth by grasses from the edges of the plots, and, since it constitutes a residue pile, it further complicates the establishment of woody species. For the creation of safe sites and consequent restoration by natural regeneration, there is a need for local elimination of Urochloa forages, without which native species are unlikely to survive.

scholarly journals Predicting Carbon Accumulation in Temperate Forests of Ontario, Canada Using a LiDAR-Initialized Growth-and-Yield Model

2020 ◽  
Vol 12 (1) ◽  
pp. 201
Author(s):  
Paulina T. Marczak ◽  
Karin Y. Van Ewijk ◽  
Paul M. Treitz ◽  
Neal A. Scott ◽  
Donald C.E. Robinson
Keyword(s):  
Carbon Stock ◽  
Temperate Forests ◽  
Species Abundance ◽  
Carbon Accumulation ◽  
Growth And Yield ◽  
Diameter Distribution ◽  
Stem Density ◽  
Yield Model ◽  
Validation Data ◽  
Aboveground Carbon

Climate warming has led to an urgent need for improved estimates of carbon accumulation in uneven-aged, mixed temperate forests, where high uncertainty remains. We investigated the feasibility of using LiDAR-derived forest attributes to initialize a growth and yield (G&Y) model in complex stands at the Petawawa Research Forest (PRF) in eastern Ontario, Canada; i.e., can G&Y models based on LiDAR provide accurate predictions of aboveground carbon accumulation in complex forests compared to traditional inventory-based estimates? Applying a local G&Y model, we forecasted aboveground carbon stock (tons/ha) and accumulation (tons/ha/yr) using recurring plot measurements from 2012–2016, FVS1. We applied statistical predictors derived from LiDAR to predict stem density (SD), stem diameter distribution (SDD), and basal area distribution (BA_dist). These data, along with measured species abundance, were used to initialize a second model (FVS2). A third model was tested using LiDAR-initialized tree lists and photo-interpreted estimates of species abundance (i.e., FVS3). The carbon stock projections for 2016 from the inventory-based G&Y model) were equivalent to validation carbon stocks measured in 2016 at all size-class levels (p < 0.05), while LiDAR-based G&Y models were not. None of the models were equivalent to validation data for accumulation (p > 0.05). At the plot level, LiDAR-based predictions of carbon accumulation over a nine-year period did not differ when using either inventory or photo-interpreted species (p < 0.05). Using a constant mortality rate, we also found statistical equivalency of inventory and photo-interpreted accumulation models for all size classes ≥17 cm. These results suggest that more precise information is needed on tree characteristics than we could derive from LiDAR, but that plot-level species information is not as critical for predictions of carbon accumulation in mixed-species forests. Further work is needed on the use of LiDAR to quantify stand properties before this technique can be used to replace recurring plot measurements to quantify carbon accumulation.

Multi-Resource Effects of Harvest, Site Preparation, and Planting in Pine Flatwoods

1983 ◽  
Vol 7 (1) ◽  
pp. 6-15 ◽  
Author(s):  
Benee F. Swindel ◽  
Wayne R. Marion ◽  
Larry D. Harris ◽  
Larry A. Morris ◽  
William L. Pritchett ◽  
...  
Keyword(s):  
Woody Species ◽  
Site Preparation ◽  
Water Yield ◽  
Multidisciplinary Study ◽  
Pine Flatwoods ◽  
Suspended Sediment Concentrations ◽  
Bedload Sediment ◽  
Natural Stands ◽  
Resource Effects ◽  
Harvest Site

Abstract A multidisciplinary study of the environmental and ecological effects of harvest, site preparation, and planting of pine flatwoods forests under two distinct management regimes is described, and important results are reported for several resources. Bedload sediment production was negligible regardless of treatment. Water yield increased during treatments, but returned to preharvest levels the following year. Stormflow increased--especially for intermediate-sized storms. Peakflow rates increased only when the stream channel was exposed to more intensive site preparation. Water quality alterations were small and transient; potassium, calcium, and suspended sediment concentrations increased. Except for calcium, nutrients in rainfall exceeded nutrients in runoff and pulpwood harvest removals. Soil and nutrient relocation with windrowing was substantial. Floral composition was dramatically altered: woody species diminished; herbaceous species increased. Plant species diversity was initially increased by less intensive practices, not diminished by more intensive practices. Small mammal populations--depauperate in the natural stands--remained so after planting. Winter bird densities increased--especially on the perimeter of undisturbed cypress domes and within clearcut pinelands.

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