scholarly journals Unassisted invasions: understanding and responding to Australia’s high-impact environmental grass weeds

2017 ◽  
Vol 65 (8) ◽  
pp. 678 ◽  
Author(s):  
Rieks D. van Klinken ◽  
Margaret H. Friedel
Keyword(s):  
Large Scale ◽  
Propagule Pressure ◽  
Natural Disturbance ◽  
Reproductive Rate ◽  
High Impact ◽  
Expert Advice ◽  
Grass Species ◽  
Natural Environments ◽  
Disturbance Regimes ◽  
Large Scale Disturbance

Alien grass species have been intentionally introduced into Australia since European settlement over 200 years ago, with many subsequently becoming weeds of natural environments. We have identified the subset of these weeds that have invaded and become dominant in environmentally important areas in the absence of modern anthropogenic disturbance, calling them ‘high-impact species’. We also examined why these high-impact species were successful, and what that might mean for management. Seventeen high-impact species were identified through literature review and expert advice; all had arrived by 1945, and all except one were imported intentionally, 16 of the 17 were perennial and four of the 17 were aquatic. They had become dominant in diverse habitats and climates, although some environments still remain largely uninvaded despite apparently ample opportunities. Why these species succeeded remains largely untested, but evidence suggests a combination of ecological novelty (both intended at time of introduction and unanticipated), propagule pressure (through high reproductive rate and dominance in nearby anthropogenically-disturbed habitats) and an ability to respond to, and even alter, natural disturbance regimes (especially fire and inundation). Serious knowledge gaps remain for these species, but indications are that resources could be better focused on understanding and managing this limited group of high-impact species. They require new management approaches, especially to counteract the advantages of ecological novelty, reduce propagule pressure and better direct the large-scale disturbance regimes that continue to shape plant communities across Australia.

scholarly journals Predicting the potential for old-growth forests by spatial simulation of landscape ageing patterns

2003 ◽  
Vol 79 (3) ◽  
pp. 621-631 ◽  
Author(s):  
Ajith H Perera ◽  
David J.B. Baldwin ◽  
Dennis G Yemshanov ◽  
Frank Schnekenburger ◽  
Kevin Weaver ◽  
...  
Keyword(s):  
Temporal Variation ◽  
Large Scale ◽  
Simulation Modelling ◽  
Spatial Simulation ◽  
Old Growth ◽  
Disturbance Regimes ◽  
Old Growth Forest ◽  
Large Scale Disturbance ◽  
Old Growth Forests ◽  
Spatio Temporal

Planning for old-growth forests requires answers to two large-scale questions: How much old-growth forest should exist? And where can they be sustained in a landscape? Stand-level knowledge of old-growth physiognomy and dynamics are not sufficient to answer these questions. We assert that large-scale disturbance regimes may provide a strong foundation to understand the spatio-temporal ageing patterns in forest landscapes that determine the potential for old growth. Approaches to describe large-scale disturbance regimes range from scenarios reconstructed from historical evidence to simulation of landscapes using predictive models. In this paper, we describe a simulation modelling approach to determine landscape-ageing patterns, and thereby the landscape potential of old-growth forests. A spatially explicit stochastic simulation model of landscape fire–forest cover dynamics was applied to a 1.8 million-ha case study boreal forest landscape to quantify the spatio-temporal variation of landscape ageing. Twenty-five replicates of 200-year simulation runs of the fire disturbance regime, at a 1-ha resolution, generated a suite of variables of landscape ageing and their error estimates. These included temporal variation of older age cohorts over 200 years, survivorship distribution at the 200th year, and spatial tendencies of ageing. This information, in combination with spatial tendency of species occurrence, constitutes the contextual framework to plan how much old-growth forest a given landscape can sustain, and where such forest could be located. Key words: landscape management, old growth, spatial simulation modelling, landscape ecology, boreal forest, Ontario, fire regime simulation, natural forest disturbances, stochastic models, age-class distribution

Recolonization dynamics of benthic macroinvertebrates after artificial and natural disturbances in an Australian temporary stream

1991 ◽  
Vol 42 (3) ◽  
pp. 295 ◽  
Author(s):  
SS Brooks ◽  
AJ Boulton
Keyword(s):  
Particle Size ◽  
Species Richness ◽  
Benthic Macroinvertebrates ◽  
Large Scale ◽  
South Australia ◽  
Natural Disturbance ◽  
Small Scale ◽  
Temporary Stream ◽  
Large Scale Disturbance ◽  
Coarse Gravel

The effects of substratum particle size (cobbles, coarse gravel and medium-fine gravel) on recolonization by benthic macroinvertebrates after disturbance was investigated in small plots (0.05 m2) in the Finniss River, an intermittent stream in South Australia. Six weeks after flow resumed, the intermediate particle size (coarse gravel) supported the greatest densities of taxa and individuals. Experimental disturbance reduced species richness by 83% and numbers of individuals by 97%. Rapid recolonizers (e.g. mayfly and stonefly nymphs) showed little substratum specificity and attained predisturbance densities within one day. Slow recolonizers (e.g. chironomid hatchlings) favoured gravel substrata and had not reached predisturbance densities within 4 days. Recolonization of small plots appeared to be by surface movement from neighbouring intact areas. A spate on Day 7 prevented further sampling, destroying all experimental plots, but this permitted a study of macroinvertebrate recolonization following a natural disturbance at a larger spatial scale. The spate reduced species richness by 45% and numbers of individuals by 70%. Vertical migration rather than drift appeared to be the major source of recolonizing fauna. Our data show that results from small-scale experiments can not be extrapolated to large-scale disturbance because the scale of disturbance strongly influences the rate and pathways of recolonization as well as the sources and faunal composition of the recolonists.

scholarly journals ShadingNet: Image Intrinsics by Fine-Grained Shading Decomposition

2021 ◽  
Author(s):  
Anil S. Baslamisli ◽  
Partha Das ◽  
Hoang-An Le ◽  
Sezer Karaoglu ◽  
Theo Gevers
Keyword(s):  
Neural Network ◽  
Large Scale ◽  
State Of The Art ◽  
Image Decomposition ◽  
Natural Environments ◽  
Decomposition Algorithms ◽  
Ambient Light ◽  
Fine Grained ◽  
Large Scale Dataset ◽  
Direct Illumination

AbstractIn general, intrinsic image decomposition algorithms interpret shading as one unified component including all photometric effects. As shading transitions are generally smoother than reflectance (albedo) changes, these methods may fail in distinguishing strong photometric effects from reflectance variations. Therefore, in this paper, we propose to decompose the shading component into direct (illumination) and indirect shading (ambient light and shadows) subcomponents. The aim is to distinguish strong photometric effects from reflectance variations. An end-to-end deep convolutional neural network (ShadingNet) is proposed that operates in a fine-to-coarse manner with a specialized fusion and refinement unit exploiting the fine-grained shading model. It is designed to learn specific reflectance cues separated from specific photometric effects to analyze the disentanglement capability. A large-scale dataset of scene-level synthetic images of outdoor natural environments is provided with fine-grained intrinsic image ground-truths. Large scale experiments show that our approach using fine-grained shading decompositions outperforms state-of-the-art algorithms utilizing unified shading on NED, MPI Sintel, GTA V, IIW, MIT Intrinsic Images, 3DRMS and SRD datasets.

Development and Testing of an Unmanned Aerial Vehicle for Large Scale Particle Image Velocimetry

2014 ◽  
Author(s):  
Christopher Pagano ◽  
Flavia Tauro ◽  
Salvatore Grimaldi ◽  
Maurizio Porfiri
Keyword(s):  
Particle Image Velocimetry ◽  
Large Scale ◽  
Field Experiments ◽  
Particle Image ◽  
Low Cost ◽  
Surface Flow ◽  
Natural Environments ◽  
Natural Stream ◽  
Image Velocimetry ◽  
Scale Particle

Large scale particle image velocimetry (LSPIV) is a nonintrusive environmental monitoring methodology that allows for continuous characterization of surface flows in natural catchments. Despite its promise, the implementation of LSPIV in natural environments is limited to areas accessible to human operators. In this work, we propose a novel experimental configuration that allows for unsupervised LSPIV over large water bodies. Specifically, we design, develop, and characterize a lightweight, low cost, and stable quadricopter hosting a digital acquisition system. An active gimbal maintains the camera lens orthogonal to the water surface, thus preventing severe image distortions. Field experiments are performed to characterize the vehicle and assess the feasibility of the approach. We demonstrate that the quadricopter can hover above an area of 1×1m2 for 4–5 minutes with a payload of 500g. Further, LSPIV measurements on a natural stream confirm that the methodology can be reliably used for surface flow studies.

Ecological processes maintaining differential tree species distributions in an Australian subtropical rain forest: implications for models of species coexistence

2000 ◽  
Vol 16 (3) ◽  
pp. 387-415 ◽  
Author(s):  
Igor Debski ◽  
David F. R. P. Burslem ◽  
David Lamb
Keyword(s):  
Species Composition ◽  
Tree Species ◽  
Rain Forest ◽  
Large Scale ◽  
Species Coexistence ◽  
Common Species ◽  
Size Class ◽  
Differential Mortality ◽  
Mixed Composition ◽  
Large Scale Disturbance

All stems ≥ 1 cm dbh were measured, tagged, mapped and identified on a 1-ha plot of rain forest at Gambubal State Forest, south-east Queensland, Australia. The spatial patterns and size class distributions of 11 common tree species on the plot were assessed to search for mechanisms determining their distribution and abundance. The forest was species-poor in comparison to many lowland tropical forests and the common species are therefore present at relatively high densities. Despite this, only limited evidence was found for the operation of density-dependent processes at Gambubal. Daphnandra micrantha saplings were clumped towards randomly spaced adults, indicating a shift of distribution over time caused by differential mortality of saplings in these adult associated clumps. Ordination of the species composition in 25-m × 25-m subplots revealed vegetation gradients at that scale, which corresponded to slope across the plot. Adult basal area was dominated by a few large individuals of Sloanea woollsii but the comparative size class distributions and replacement probabilities of the 11 common species suggest that the forest will undergo a transition to a more mixed composition if current conditions persist. The current cohort of large S. woollsii individuals probably established after a large-scale disturbance event and the forest has not attained an equilibrium species composition.

scholarly journals Ecological Impacts of Megaprojects: Species Succession and Functional Composition

Plants ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 2411
Author(s):  
Hamada E. Ali ◽  
Solveig Franziska Bucher
Keyword(s):  
Plant Species ◽  
Large Scale ◽  
Invasive Plant ◽  
Species Traits ◽  
Natural Vegetation ◽  
Ecological Impacts ◽  
Imperata Cylindrica ◽  
Dry Matter Content ◽  
Large Scale Disturbance ◽  
The Impact

Land-use changes have huge impacts on natural vegetation, especially megaprojects, as the vegetation layer is destroyed in the course of construction works affecting the plant community composition and functionality. This large-scale disturbance might be a gateway for the establishment of invasive plant species, which can outcompete the natural flora. In contrast, species occurring in the area before the construction are not able to re-establish. In this study, we analyzed the impact of a pipeline construction on a wetland nature reserve located in northern Egypt. Therefore, we analyzed the plant species occurrence and abundance and measured each plant species’ traits before the construction in 2017 as well as on multiple occasions up to 2 years after the construction had finished on altogether five sampling events. We found that the construction activity led to the establishment of an invasive species which previously did not occur in the area, namely, Imperata cylindrica, whereas five species (Ipomoea carnea, Pluchea dioscoridis, Polygonum equisetiforme, Tamarix nilotica, and Typha domingensis) could not re-establish after the disturbance. The functionality of ecosystems assessed via the analysis of plant functional traits (plant height, specific leaf area, and leaf dry matter content) changed within species over all sampling events and within the community showing a tendency to approximate pre-construction values. Functional dispersion and Rao’s quadratic diversity were higher after the megaproject than before. These findings are important to capture possible re-establishment and recovery of natural vegetation after construction and raise awareness to the impact of megaprojects, especially in areas which are high priority for conservation.

scholarly journals A Multi-Site Evaluation of Winter Hardiness in Indigenous Alfalfa Cultivars in Northern China

Atmosphere ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1538
Author(s):  
Lijun Xu ◽  
Qian Liu ◽  
Yingying Nie ◽  
Feng Li ◽  
Guixia Yang ◽  
...  
Keyword(s):  
Large Scale ◽  
Production Systems ◽  
Comprehensive Evaluation ◽  
Perennial Grass ◽  
Cropping System ◽  
Northern China ◽  
Winter Hardiness ◽  
Grass Species ◽  
Average Score ◽  
Field Evidence

Integration of perennial grass species into the current food production systems, especially in the agropastoral regions worldwide, may produce multiple benefits including, among others, a more stable productivity and a smaller eco-environmental footprint. However, one of the fundamental challenges facing the large-scale adoption of such grass species is their ability to withstand the vagaries of winter in these regions. Here, we present a comprehensive evaluation of the winter hardiness of 50 indigenous Chinese cultivars of alfalfa, a high-quality leguminous perennial grass, in comparison with six introduced U.S. cultivars in a multi-site field experiment in northern China. Our results reveal that indigenous cultivars have stronger winter hardiness than introduced cultivars. Cultivars native in the north performed better than southern cultivars, suggesting that suitability evaluation is an unavoidable step proceeding any regional implementations. Our results also show that the metric we used to assess alfalfa’s winter hardiness, the average score index (ASI), produced more consistent results than another more-widely used metric of winter survival rate (WSR). These findings offer a systematic field evidence that supports regional cropping system adjustment and production system betterment to ensure food security under climate change in the region and beyond.

scholarly journals Genetic Transformation of Apomictic Grasses: Progress and Constraints

2021 ◽  
Vol 12 ◽  
Author(s):  
Andrés M. Bellido ◽  
Eduado D. Souza Canadá ◽  
Hugo R. Permingeat ◽  
Viviana Echenique
Keyword(s):  
Genetic Transformation ◽  
Plant Transformation ◽  
Large Scale ◽  
Crop Improvement ◽  
Current Status ◽  
Grass Species ◽  
Brachiaria Brizantha ◽  
Apomictic Species ◽  
Transformation Methods

The available methods for plant transformation and expansion beyond its limits remain especially critical for crop improvement. For grass species, this is even more critical, mainly due to drawbacks in in vitro regeneration. Despite the existence of many protocols in grasses to achieve genetic transformation through Agrobacterium or biolistic gene delivery, their efficiencies are genotype-dependent and still very low due to the recalcitrance of these species to in vitro regeneration. Many plant transformation facilities for cereals and other important crops may be found around the world in universities and enterprises, but this is not the case for apomictic species, many of which are C4 grasses. Moreover, apomixis (asexual reproduction by seeds) represents an additional constraint for breeding. However, the transformation of an apomictic clone is an attractive strategy, as the transgene is immediately fixed in a highly adapted genetic background, capable of large-scale clonal propagation. With the exception of some species like Brachiaria brizantha which is planted in approximately 100 M ha in Brazil, apomixis is almost non-present in economically important crops. However, as it is sometimes present in their wild relatives, the main goal is to transfer this trait to crops to fix heterosis. Until now this has been a difficult task, mainly because many aspects of apomixis are unknown. Over the last few years, many candidate genes have been identified and attempts have been made to characterize them functionally in Arabidopsis and rice. However, functional analysis in true apomictic species lags far behind, mainly due to the complexity of its genomes, of the trait itself, and the lack of efficient genetic transformation protocols. In this study, we review the current status of the in vitro culture and genetic transformation methods focusing on apomictic grasses, and the prospects for the application of new tools assayed in other related species, with two aims: to pave the way for discovering the molecular pathways involved in apomixis and to develop new capacities for breeding purposes because many of these grasses are important forage or biofuel resources.

scholarly journals Large-scale disturbance legacies and the climate sensitivity of primary Picea abies forests

2018 ◽  
Vol 24 (5) ◽  
pp. 2169-2181 ◽  
Author(s):  
Jonathan S. Schurman ◽  
Volodymyr Trotsiuk ◽  
Radek Bače ◽  
Vojtěch Čada ◽  
Shawn Fraver ◽  
...  
Keyword(s):  
Picea Abies ◽  
Climate Sensitivity ◽  
Large Scale ◽  
Large Scale Disturbance
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