Open Woodland Research Articles

Measuring plot scale woodland structure using terrestrial laser scanning

AbstractTerrestrial laser scanning (TLS) can be used to characterize a woodland site by measuring structural attributes of the vegetation community. In Australia, government funded programs monitor vegetation structure using manual field surveys to assess change and ecological condition. In this study, we examined whether structural attributes commonly assessed in woodland ecology surveys can be extracted from a single TLS scan. Attributes of the ground, shrub and overstory vegetation layers were evaluated at nine open woodland sites in central Western Queensland. We used 0.1 m voxels to aggregate returns. Our results show that, compared with field assessment by highly experienced ecologists, TLS can rapidly characterize structural attributes for tree canopy cover, maximum tree height, average tree height (R2 > 0.9) and average diameter at breast height (R2 = 0.77). However, we could not accurately determine shrub height, shrub canopy cover, shrub average height, ground cover (grass, litter and coarse woody debris) or the number of trees per hectare (R2 < 0.45). By analysing local minima in the histogram of the maximum height, we determined height thresholds for canopy strata, and applied these to determine the canopy layer with the most biomass – the ecologically dominant layer (EDL). While these results are promising for overstory assessment and defining canopy strata heights using TLS, they suggest that future research should focus on investigating improved classification methods to separate laser returns into shrub and tree objects for structural assessment at the plot scale.

AUTOMATED MAPPING WITH LiDAR AND SPECTRAL CHARACTERIZATION IN MEDITERRANEAN FOREST AGROECOSYSTEMS

Mapping with LiDAR data is not a standardized practice, though LiDAR databasesare increasing in all countries in Europe. We develop and test a simple method forautomated land-cover mapping. The study area was a farm located at a natural parkof southern Spain. It comprises 502 ha covered by Mediterranean forestagroecosystems, like dehesa (a very open woodland of scattered evergreen treesused by grazing animals), woodland and scrubland, and transitions among them,composing a heterogeneous landscape. This heterogeneity is caused by variationsin holm and cork oak tree density and a sclerophyllous shrub cover, i.e., 3Dstructure of woody vegetation. Using aerial photographs digitization, Landsatimage classification, and image segmentation of tree crowns, land-cover maps weregenerated. Besides, other maps were produced from LiDAR-derived canopy coverand height of tree vegetation and shrub stratum. These 3D variables allowed to awall-to-wall characterization of woody vegetation land-cover classes in the studyarea, that was completed with a NDVI assessment. The results show that automatedmapping with LiDAR is reliable and accurate enough in comparison with othermapping techniques. It outperforms them because its higher spatial resolution, andcan be combined with other remote sensing methods to provides an improvedunderstanding of forest landscapes.

Detection of Forest Disturbance With Spaceborne Repeat-Pass SAR Interferometry

Focusing on open forests and woodlands within the Injune Landscape Collaborative Project research area in central southeast Queensland, Australia, and using dual-pol (HH and HV) ALOS PALSAR repeat-pass InSAR data (temporal baseline of 92 days), this paper explores the detection of forest disturbance from the spaceborne repeat-pass InSAR correlation magnitude by developing a simple and efficient forest disturbance detection approach. In particular, a generic physical InSAR scattering model is derived by accounting for the forest disturbance information as well as the normal temporal decorrelation effects that are later compensated for using the modified Random Volume over Ground model. Based on the generic model, a quantitative indicator of forest disturbance is retrieved, namely, disturbance index that varies from 0 (no disturbance) to 1 (complete deforestation). This index is compared with that identified using a time series of Landsat sensor data over a selective logging area and has a relative root mean square error of 13% at a spatial resolution of 0.8 ha. This paper highlights the use of the co-pol InSAR correlation magnitude for forest disturbance detection, which serves as a complimentary application to using the cross-pol counterpart for forest height inversion in a companion work. Given the global availability of this type of data (e.g., Japanese Aerospace Exploration Agency’s ALOS-1/2 and NASA-ISRO’s NISAR), the method is anticipated to contribute to the range of tools being developed for large-scale forest disturbance assessment and monitoring.

Nam Lot (MIS 5) and Duoi U'Oi (MIS 4) Southeast Asian sites revisited: Zooarchaeological and isotopic evidences

The Nam Lot site in Laos and the hominin-bearing Duoi U'Oi site in Vietnam are dated to MIS 5 (86–72 ka) and MIS 4 (70–60 ka), respectively. Located in the same latitudinal belt ~20°N in the north of the Indochinese area, the faunal assemblages recovered from breccia deposits in a karstic context have the potential to provide information on the palaeoenvironmental conditions faced by earliest modern humans when they entered the Southeast Asian mainland. Here, zooarchaeological evidence of faunas are reviewed combined with a new stable isotope analysis (δ13C and δ18O) of tooth enamel of mammals from Nam Lot (86–72 ka), to explore environmental conditions during MIS 5–4 periods.In both sites, large predators (hyena, tiger, leopard, and dhole) had access to a great diversity of prey among mammals. The Nam Lot isotopic results indicate during MIS 5 a complexity in the forest habitats with closed low-light tropical rainforest, “intermediate” rainforest, and C3–C4 open woodland/‘savanna’. This woodland ecosystem – notably the “intermediate” rainforest – carried most of the ungulate biomass, with a variety of small to large-bodied ground-dwelling animals.

Spatial diversity of clavarioid mycota (Basidiomycota) at the forest-tundra ecotone

The article studies the change of clavarioid mycota species richness along the longitudinal gradient of climatic continentality in the forest tundra ecotone of Eurasia and the results are discussed for continental and regional levels using the basic climatic variables. It was found that species richness declines, both continentally and regionally, with climate continentality increasing. The Fennoscandian sector situated in the mild maritime climate is the richest, whereas Yakutia, with an ultracontinental harsh climate is the poorest. Strong positive correlations were found between species richness and mean annual temperature and precipitation. On the other hand, spatial turnover of species, or beta diversity, has a negative correlation with the macroclimatic gradient. There are European sectors, where clavarioid mycota associating with the birch and pine-spruce open woodlands have high similarity with their boreal variants, whereas in Siberian sectors, east of the Yenisei River, where mycota is associated with larch and cedar elfin bushes, the similarities are more akin to tundra variants. At the continental scale, there is no reliable relationship between mycota diversity with the flora richness and soil pH, but the permafrost thickness is significantly correlated with the studied levels of the clavarioid mycota diversity.

Giraffe Mother-Calf Relationships in the Miombo Woodland of Katavi National Park, Tanzania

Both predator pressure and habitat type influence mother-offspring relationship. Giraffe's herd size and herd composition can be influenced by these two environmental factors. We sought to uncover whether predator pressure and habitat type also have an impact on giraffe mother-calf proximity and time spent together. We studied giraffe mother-calf relationships to compare mother-calf dyadic relationships in dense woodland with those reported in open woodlands. We collected data from three calves (within the first six months after birth) and their mothers at the miombo woodland of Katavi National Park, Tanzania. We observed the mother giraffe leaving or staying with her calf and recorded the initiation and termination of each of these behaviors. We found that the duration of both states was rarely more than 1 h. We never observed a mother leaving her calf for more than 1.5 h, as has been reported in open woodlands. We found that in calf-calf dyads, giraffe were more likely to maintain closer proximity to one another than in female-calf dyads. Our results suggest that the flexibility recorded in mother-calf social relationships is influenced by both social and ecological factors, differing to some extent in tree density, food preference during nursing, and predators' prey preference.

The paleoecology of Pleistocene birds from Middle Bed II, at Olduvai Gorge, Tanzania, and the environmental context of the Oldowan-Acheulean transition

Fossil bird data (community composition and taphonomic profiles) are used here to infer the environmental context of the Oldowan-Acheulean transitional period at Olduvai Gorge, Tanzania. This is the first comprehensive report on the Middle Bed II avifauna and includes fossils excavated by the Olduvai Geochronology and Archaeology Project (OGAP) and recently rediscovered fossils collected by Mary Leakey. Crane, ibis, darter, owl, raptor, crow, and vulture are reported from Bed II for the first time. The presence of these taxa, absent earlier in this Bed, point to a general opening and drying of the landscape with grassland and open woodland expansion. Taxa associated with dense, emergent wetland vegetation, such as dabbling ducks and rails, are uncommon and less diverse than earlier in Bed II. This suggests more mature wetlands with clearer waters. Cormorants continue to be common, but are less diverse. Cormorants and other roosting taxa provide evidence of trees in the area. Compared to lowermost Bed II, the Middle to Upper Bed II landscape is interpreted here as more open and drier (but not necessarily more arid), with matured wetlands, scattered trees, and a greater expansion of grasslands.

A Holistic Approach to the Evaluation of the Montado Ecosystem Using Proximal Sensors.

The Montado is a silvo-pastoral system characterized by open canopy woodlands with natural or cultivated grassland in the undercover and grazing animals. The aims of this study were to present several proximal sensors with potential to monitor relevant variables in the complex montado ecosystem and demonstrate their application in a case study designed to evaluate the effect of trees on the pasture. This work uses data collected between March and June 2016, at peak of dryland pasture production under typical Mediterranean conditions, in twenty four sampling points, half under tree canopy (UTC) and half outside tree canopy (OTC). Correlations were established between pasture biomass and capacitance measured by a commercial probe and between pasture quality and normalized difference vegetation index (NDVI) measured by a commercial active optical sensor. The interest of altimetric and apparent soil electrical conductivity maps as the first step in the implementation of precision agriculture projects was demonstrated. The use of proximal sensors to monitor soil moisture content, pasture photosynthetically active radiation and temperature helped to explain the influence of trees on pasture productivity and quality. The significant and strong correlations obtained between capacitance and pasture biomass and between NDVI and pasture nutritive value (in terms of crude protein, CP and neutral detergent fibre, NDF) can make an important contribution to determination of key components of pasture productivity and quality and implementation of site-specific pasture management. Animal tracking demonstrated its potential to be an important tool for understanding the interaction between various factors and components that interrelate in the montado ecosystem and to support grazing management decisions.

Livestock grazing reinforces the competitive exclusion of small‐bodied birds by large aggressive birds

Abstract Grazing by domestic livestock is sometimes promoted as a management tool to benefit biodiversity. In many situations, however, it can produce negative outcomes. Here, we examine the impacts of recent and historic livestock grazing on bird communities in the semi‐arid woodlands in eastern Australia, testing the notion that grazing removes the suppressive effect of structurally complex vegetation on miners, thereby reducing the richness and abundance of small birds. We used time‐ and area‐limited searches of 108 sites varying in livestock grazing history and intensity, to explore the direct and indirect effects of grazing, habitat complexity and the abundance of aggressive, large‐bodied birds on smaller‐bodied birds using two‐way analysis of variance and structural equation modelling. Small birds were less abundant and had lower richness in the presence of miners. Our structural equation models indicated that recent grazing had direct suppressive effects on the abundance of miners, and both richness and abundance of all but the largest‐bodied bird groups. However, higher levels of historic livestock grazing reinforced the competitive exclusion of the six small‐bodied bird groups (insectivores, nectarivores, declining woodland birds, small ground‐foraging birds, all small birds and all non‐miners) by aggressive miners via reductions in habitat complexity. Moreover, the strength of any suppressive effects on small birds or positive effects on large birds by miners increased with increasing miner abundance. Synthesis and applications. Our results highlight the importance of vegetation structural complexity, not only for providing habitat for woodland birds, but also as barriers to the invasion and competitive dominance of miners. Our findings suggest that management actions aimed at reducing tree and shrub density to promote open woodlands are likely to have significant negative consequences for the conservation of small woodland birds.

Phylogenetic Relationships, Pathogenic Traits, and Wood-Destroying Properties of Porodaedalea niemelaei M. Fischer Isolated in the Northern Forest Limit of Larix gmelinii Open Woodlands in the Permafrost Area

Phylogenetic Relationships, Pathogenic Traits, and Wood-Destroying Properties of Porodaedalea niemelaei M. Fischer Isolated in the Northern Forest Limit of Larix gmelinii Open Woodlands in the Permafrost Area

The genus Opisthacanthus Peters, 1861 (Scorpiones: Hormuridae), a remarkable Gondwanian group of scorpions

New comments are proposed on the geographic distribution of genus Opisthacanthus, and the Gondwanian model is further supported. The diversity of the genus is extraordinary in Madagascar, with the same number of species as in continental Africa, but sub-Saharan Africa is home to six out of the nine groups currently recognized of Opisthacanthus. Given the affinities of the Opisthacanthus groups and their current distribution, a center of origin in Africa could be favored for these ancient scorpions. The proposed Gondwana model suggests that the Madagascar Opisthacanthus are closer to those of the New World, which is consistent with the affinities observed in morphological characters. A new species, Opisthacanthus titanus sp. n., is described from the Torotorofotsy Forest, located in Eastern Madagascar. The new species shows affinities with both Opisthacanthus madagascariensis Kraepelin, 1894 known from dry regions in the western portion of the island and Opisthacanthus lavasoa Lourenço, Wilmé & Waeber, 2016 only known from the extreme southeast of the island. The new species and O. madagascariensis have similar external morphologies but the morphometric values are markedly distinct. Moreover, O. madagascariensis is exclusively found in spiny forest thickets and open woodlands, whereas the new species was found in the humid forest of Torotorofotsy. The total number of species in Madagascar is now raised to twelve. Biogeographical scenarios are also proposed to infer the origin of the Opisthacanthus and better understand its distribution in the New World, in Africa and Madagascar.

Open woodland tree and shrub dynamics and landscape function in central Queensland after killing the trees with herbicide

Herbicides are used in savanna to control tree and shrub density, primarily to maintain the value of the country for pastoral enterprises. However, the concomitant effects on biodiversity and landscape functioning need to be recognised and better understood. This study monitored tree and shrub dynamics and eventual landscape functionality in response to tree-killing over 7–8 years at two open eucalypt woodland sites in central Queensland. Paddocks denuded of trees using herbicide or not so treated were subject to three differing grazing pressures by cattle. Similarly treated but ungrazed sets of plots were subjected to either regular spring burns or were rarely burnt. Tree and shrub growth and seedling recruitment were slightly affected by grazing pressure but regular spring burns minimised recruitment of minor woodland species and reduced the population of original saplings and seedlings that survived the herbicide. Few eucalypt seedlings emerged from soil surface samples taken each spring in any treatment, despite the presence of flowering trees in half the treatments. Capture and retention of resources, particularly rainfall and nutrients, were slightly improved by killing the trees, and worsened by grazing. We conclude that killing trees with herbicide at these sites did not adversely affect landscape function and that woody species regeneration was almost inevitable on these open eucalypt woodland native pastures.

Elevated temperatures are associated with stress in rooftop-nesting Common Nighthawk (Chordeiles minor) chicks.

Grasslands and riparian forests in southeastern South Dakota have been greatly reduced since historical times, primarily due to conversion to row-crop agriculture. Common Nighthawk (Chordeiles minor) nesting habitat includes grasslands, open woodlands and urban rooftops, but nesting sites in southeastern South Dakota are confined to rooftops, as natural nesting habitat is limited. Nighthawks nesting on exposed rooftop habitats may encounter thermal conditions that increase operative temperatures relative to vegetated land cover types. Mean humidity has increased and mean wind speed and cloud cover have decreased during the nighthawk breeding season from 1948 to 2016 in southeastern South Dakota. These changes might contribute to increasing operative temperatures at exposed rooftop nest sites and this could influence chick condition. We studied nest micro-climate and the plasma stress response for 24 rooftop-nesting nighthawk chicks from 17 nests during 2015 and 2016. High humidity prior to blood collection reduced both baseline and stress-induced plasma corticosterone (CORT). In contrast, high maximum temperatures during the day before sampling increased stress-induced CORT. The magnitude of the chick stress response was significantly negatively related to maximum wind speed for the week prior to CORT measurement. Other weather and micro-climate variables were not significant effectors of CORT metrics. Most chicks had low baseline CORT and were able to mount a stress response, but a subset of chicks (n = 4) showed elevated baseline CORT and a negative association between the magnitude of stress response and ambient temperature. For this subset, mean ambient temperature for the day before sampling was significantly higher (2.3°C) than for chicks with typical baseline CORT levels. These data suggest that regional climate change trends could affect the ability of nighthawk chicks to mount a stress response, which, in turn, might influence the susceptibility of nighthawk chicks to climate change in the Northern Prairie region.

Bird Population Changes Following the Establishment of a Diverse Stand of Woody Plants in a Former Crop Field in North Dakota, 1975–2015

Changes in the coverage of trees and shrubs on the North Dakota landscape since Euro-American settlement have likely had a pronounced impact on bird species that favor woody vegetation. Long-term data sets on breeding bird populations in wooded habitats in North Dakota or in the Great Plains are scarce. In 1975 a wildlife habitat plot was established in a 10.5 ha cropland field with a long history of small-grain production. The objective of this article is to evaluate the successional changes in bird populations as the habitat at this site became more biologically and structurally complex after the establishment of a diverse stand of shrubs and trees. Between 1975 and 2015, 103 species or varieties of native and non-native trees, shrubs, or vines were planted in this wildlife habitat plot (hereafter woodlot); 58.2% of those species were still present in 2016. The avian community in the woodlot increased in abundance and diversity as the woody vegetation increased in complexity and maturity, but the changes in abundance varied among ecological bird groups. Grassland bird abundance remained relatively constant but uncommon throughout the four decades after woody vegetation was first established. Bird species associated with shrublands and open woodlands and edges responded positively and showed the greatest increases in abundance during the 41-year period. The abundance of bird species associated with open areas with scattered trees or shrubs (i.e., savanna habitat) increased during the first half of the study but declined during the second half. Bird species associated with forest habitats were rare throughout the 41-year period, but their abundance increased during the most recent two decades. Results of this study are important for informing decisions about restoration efforts of riparian forests and other native wooded areas in the Great Plains and setting expectations for the time-scale required for the return of assemblages of species of woodland birds.

Relationships between mature trees and fire fuel hazard in Australian forest

Increasing density of mid-storey vegetation since European settlement has been observed in forests and woodlands in several parts of the world and may result in greater fire fuel hazard. This phenomenon is often attributed to a longer interval between fires since European settlement, but may also be influenced by tree removal during the same period. We hypothesised that the number of mature trees in a stand reduces mid-storey vegetation cover and the associated fire fuel hazard through competition. To test this hypothesis, we examined associations between mid-storey cover and fire fuel hazard and the mean diameter of trees within stands of open forest and woodland in south-eastern Australia, a region prone to wildfires. We found that vegetation cover between 2 and 4 m and 4 and 6 m above the ground and two measures of fire fuel hazard were negatively associated with the quadratic mean tree diameter. Our results suggested that the removal of mature trees since European settlement may have triggered tree and shrub regeneration, resulting in higher mid-storey cover and fire fuel hazard. Thus, managing stands for the persistence and replacement of mature trees may contribute to long-term fuel reduction in Australian forests and woodlands.

Confirmation of little eagle (Hieraaetus morphnoides) migration by satellite telemetry

The post-breeding migration of an adult male little eagle (Hieraaetus morphnoides) was followed from south-eastern Australia to the Northern Territory using a GPS satellite transmitter. The bird bred in open woodland habitat on the edge of the city of Canberra, Australian Capital Territory (ACT), before it flew more than 3300km in 18 days, to winter in an area of eucalypt savannah in the Northern Territory. It remained there for 59 days, within a range of ~30km2, after which the last signal was transmitted. The bird was subsequently resighted back in its ACT territory at the end of winter, thus completing a return migration. This is the first confirmation of post-breeding migration for the species.

Assessing large area forest cover products derived from the same imaging source across Victoria, Australia

SummaryForest cover products are an essential tool for land managers and policy makers. They are used at a variety of spatial scales to inform decision‐making and policy across a range of ecosystem drivers and services. This article compares three forest cover products (FCP), all of which were created using Landsat satellite imagery, but using different methodologies and covering different spatial extents that range from global to state. It also explores their use and utility across the state of Victoria, Australia. It asks the question, how interchangeable are the forest cover maps? FCP are also validated against a very high‐resolution reference data set. Overall accuracy was around 89% for the state and national FCP, and 84% for the global FCP. The global map produced the lowest estimate of total forest cover, while estimates obtained by the national and state FCP were similar across the study area. Spatially, differences, however, were apparent. The national forest cover map obtained higher estimates across most of Victoria except in the most arid region which is dominated by low open woodland. While the national and global scale forest cover maps were found to have good diagnostic ability for large area assessment and reporting, their use for land management is not optimal and can lead to gross error.

Shoreline displacement and human resource utilization in the southern Baltic Basin coastal zone during the early Holocene: New insights from a submerged Mesolithic landscape in south-eastern Sweden

Along parts of the Hanö Bay coast in south-eastern Sweden, remains of a submerged landscape can be found down to depths of almost 25 m b.s.l. The coastal landscape was formed during two periods of lowered water levels in the Baltic Basin: the Yoldia Sea and the Initial Littorina Sea stages. In order to reconstruct the local environment and shoreline displacement during the Yoldia Sea and Ancylus Lake stages, sediment sequences were obtained at 4.5, 17.5 and 18.7 m b.s.l. Detailed bathymetric mapping was based on multi-beam echo-sounding while surveillance and sampling of tree remains and archaeological findings were performed through diving. The Yoldia Sea low-stand reached its minimum level at 24–25 m b.s.l. just before 10,800 cal. BP. During the subsequent Ancylus transgression, a slow-flowing river passed through the area, accumulating thick deposits of fine-grained organic sediments in lagoonal basins. The river was surrounded by open woodland dominated by pine. Based on successive flooding of rooted tree stumps, the transgression rate was estimated at 4 cm·yr−1, until the Ancylus high-stand was reached at 5 m b.s.l. at 10,400–10,300 cal. BP. Findings of worked aurochs and beaver bones provide evidence of human presence in the landscape and show the importance of terrestrial resources for their subsistence. These integrated palaeoecological and archaeological investigations demonstrate the importance of submerged landscapes with well-preserved sediment, wood and bone material for our understanding of southern Baltic coastal landscapes and their inhabitants during the Early Mesolithic.

Melanoplus nossi Hill (Orthoptera: Acrididae): A Grasshopper Species Endemic to the North American Coastal Plain ?

ABSTRACT Additional distribution records and habitat information is presented for Melanoplus nossi. Based on the information currently available, M. nossi appears to be endemic to the North American Coastal Plain where it inhabits a variety of open forest or woodland conditions.

Shading, nitrogen and soil texture rule a sandy savanna: Does facilitation rule its patchy physiognomy as well?

Oligotrophic sandy ecosystems have been the subject of investigations into understanding assembly rules because of their harsh conditions. Light, nitrogen availability and soil texture can cause constraints in oligotrophic sandy ecosystems, but can be attenuated by shading. This work aimed to answer the following questions. How do light (shading), soil texture and nitrogen interact in ruling an oligotrophic sandy savanna? Does the assemblage of patchy savanna differ from the assemblage of other physiognomies? If it differs, could the assemblage of patchy savanna be explained by plant–plant facilitation? Five circular plots (radius=3m) were established in each of five different physiognomies (25 plots in total): grassland, open savanna, patchy savanna, closed savanna and woodland. We identified and collected adult leaves of every individual plant inside the plots for measuring nitrogen (leaf nitrogen concentration, δ15N and C/N). We took hemispherical photos for quantification of light and collected compound soil samples for measuring soil nitrogen and soil texture. We performed generalized linear mixed models and richness estimates in order to test the influences of light (shading), nitrogen (leaf concentration, soil content, δ15N and leaf C/N) and soil properties on communities of a tropical sandy savanna. Light was not related to soil nitrogen, but was negatively related to leaf nitrogen concentration, to clay and to coarse sand, and positively related to fine sand. Leaf nitrogen concentration was negatively related to C/N and to δ15N. Compared to grassland and open savanna, patchy savanna, closed savanna and woodland were significantly richer in species and had higher leaf nitrogen concentration, higher leaf δ15N and lower leaf C/N. Patchy savanna was more shaded and had more species than expected, according to the relationship of light and species richness with fine sand. Compared to other physiognomies, the distinctive assemblage of patchy savanna suggests plant–plant facilitation as an assembly rule.