Strangler Figs in a Stand of Dry Rainforest in the Lower Hunter Valley,NSW

A complete census was conducted of all hemi-epiphytic Ficus individuals within a single stand of dry rainforest. Substrate analyses were conducted on the material from potential hemi-epiphyte germination sites in an attempt to understand the factors influencing the distribution of hemi-epiphytic Ficus individuals within the stand. In all, 191 individuals of Ficus macrophylla ssp. macrophylla (Moreton Bay fig) and 65 individuals of Ficus superba var. henneana (deciduous fig) were found within the stand, providing a mean hemi-epiphyte density of 13.5/ha. Clear host preferences were shown for both fig species with two species, Olea paniculata (native olive) and Drypetes deplanchei (yellow tulip), shown to host 60 per cent and 21 per cent, respectively, of all hemi-epiphytes within the stand. These host trees are characterised by humus pockets that accumulate in depressions on their branches and trunk, as well as in branch axils. Their host potential is thought to be enhanced by the increased visitation of birds that feed on the fruit from both the hemi-epiphytes and these potential host trees. Substrate analyses revealed that while the highly organic epiphytic and rock-surface substrates had a high field capacity, their moisture holding capacity was low. The ponding of water and the reduced desiccation afforded by the microtopography of the germination sites ensures that these sites are more likely to maintain a viable moisture content. It appears that desiccation of the germination substrate could be the major cause of the high rate of juvenile hemi-epiphytic Ficus mortality.     

A review of soil and geological maps of the Nepean River terraces,NSW

The Nepean River terraces are a sequence of Tertiary and Quaternary alluvial deposits to the west of Sydney, NSW. In the last 85 years over 20 soil and geological maps covering the area have been produced. Errors and interpretations introduced in early regional scale maps were perpetuated for over 40 years despite numerous new editions. Regional scale geological maps in the 1950s and 1960s failed to take account of good detailed work by geographers, soil surveyors and geology students. Detailed geological and soil stratigraphic mapping in the past 10 years drew attention to these problems and has highlighted the important contributions made by the earlier detailed studies. New interpretations can now be tested against a substantial body of data. Contemporary regional soil and geological maps have taken account of these detailed studies and so present a more consistent approach than in the past.     

Rift kinematics preserved in deep-time erosional landscape below the northern North Sea

Our understanding of continental rifting is, in large parts, derived from the stratigraphic record. This record is, however, incomplete as it does not often capture the geomorphic and erosional signal of rifting. New 3D seismic reflection data reveal a Late Permian-Early Triassic landscape incised into the pre-rift basement of the northern North Sea. This landscape, which covers at least 542 km², preserves a drainage system bound by two major tectonic faults. A quantitative geomorphic analysis of the drainage system reveals 68 catchments, with channel steepness and knickpoint analysis of catchment-hosted palaeo-rivers showing that the landscape preserved a >2 Myr long period of transient tectonics. We interpret that this landscape records a punctuated uplift of the footwall of a major rift-related normal fault (Vette Fault) at the onset of rifting. The landscape was preserved by a combination of relatively rapid subsidence in the hangingwall of a younger fault (Øygarden Fault) and burial by post-incision sediments. As such, we show how and why erosional landscapes are preserved in the stratigraphic record, and how they can help us understand the tectono-stratigraphic evolution of ancient continental rifts.     

Water planning priorities and conflicts in The Hunter Valley,NSW

This paper examines the ability of society to develop and allocate water resources during a time of major drought and industrial growth. Water shortage in the upper Hunter became apparent between 1979 and 1983. Even the well watered Newcastle metropolitan area experienced domestic and commercial restrictions. Strategies to deal with the immediate problems in inland areas included temporary water restrictions, cessation of issue of new irrigation licences, institution of volumetric water allocation to agriculture and appeals for public cooperation. Government was placed under pressure to provide sufficient industrial water, maintain supplies to agriculture and distribute water resource information to private and public sector decision makers. Major regional water planning initiatives were almost as slow to eventuate as those for social infrastructure provision. Such crises are likely to recur. Questions remain as to the desirability and sufficiency of current allocative mechanisms to cope with the future diversity of water needs.     

Actual and potential flood damage: a case study for urban Lismore,NSW, Australia

An urban land use survey of Lismore, New South Wales, was undertaken to assess the character of buildings affected by the major flood of March 1974. A questionnaire survey was then carried out on a sample of 140 residential houses, 212 commercial establishments and all 26 industrial concerns in the flood-prone area to assess actual flood damage. Potential flood damage was estimated by a professional valuer and by questionnaire information. Comparison of actual and potential damage showed that actual damage was only 52.4 per cent of potential damage in the residential sector, 23.5 per cent in the commercial sector and 6.1 per cent in the industrial sector. It is concluded that the relatively low levels of actual damage reflect the high degree of preparedness by the urban population, particularly in the commercial and urban sector. The results indicate the level of damage reduction feasible given adequate flood warning schemes and appropriate adjustments by the community.     

Spatial and temporal rockfall activity in a forest stand in the Swiss Prealps—A dendrogeomorphological case study

Rockfall is a major threat to settlements and transportation routes in large parts of the Alps. While protective forest stands in many locations undoubtedly reduce rockfall risk, little is known about the exact frequency and spatial distribution of rockfall activity in a given place or about how these parameters can be assessed. Therefore, the objective of the present study was to reconstruct rockfall events with dendrogeomorphological methods and to analyse the spatial and temporal rockfall activity in a subalpine forest stand. The study site is located in the transit zone of frequently passing, rather small rockfall fragments (mean diameter of 10 to 20 cm). In all, 33 stem discs from previously felled Picea abies trees found at the foot of Schwarzenberg in Diemtigtal (Swiss Prealps) were sampled, and a total number of 301 rockfall events were dated to between A.D. 1724 and 2002.Results showed that the spatial distribution of rockfall changed slightly with time, and that rockfall activity increased considerably over the last century. In contrast, rockfall magnitude presumably remained on a comparable level. The seasonal occurrence of rockfall showed a clear peak during the dormant season of trees, most probably in early spring. Furthermore, on a 10-year moving average basis, rockfall rates were positively correlated with mean annual as well as summer and winter temperatures. This means that higher temperatures resulted in increased rockfall activity. On the other hand, no correlation with annual or seasonal precipitation totals was revealed. Overall, this study provides an appropriate method for the detailed assessment of spatial and temporal variations in rockfall activity in a given place.     

Stone pillar rockfall in Danxia landform area,Mt. Langshan,Hunan Province,China

A typical Danxia stone pillar, Leipishi I, in the World Natural Heritage site at Mt. Langshan, China, collapsed on 2 November 2009. To understand the mechanism controlling this rockfall event, uniaxial compressive strength, tensile strength, resistance against sulfuric acid, and freezing and thawing properties were analyzed from 44 sandstone and conglomerate cores collected from the Lanlong Formation, the only exposed formation on Mt. Langshan. In addition, four rock slices were created for analysis under a polarizing microscope. A detailed reconstruction of the geometry and restraint conditions of the stone pillar in place before the rockfall occurred permitted an estimation of the stress state before collapse using 3D finite-element code. The results show that the rapid retreat of soft, intercalated rock layers due to weathering can profoundly change the stress state within the rock body, causing compressive or tensile stresses to rise above compressive or tensile strengths in specific sections of a rock body, and causing partial or complete collapse.     

Change and adaptation in four rural communities in New England,NSW

The negative image created by a preoccupation with population losses in some rural areas and the decline in some economic and service functions in many small country towns has masked the considerable improvements which have occurred there. Insufficient attention has been given to the raised level of living in many rural locations which has increased the attraction of a rural lifestyle. Local shire councils have played an important role in enhancing the quality of local life through investment in new town facilities, and residents record a high level of community satisfaction. Although past social and economic roles are changing in rural locations, new functions are emerging in four settlements in New England, NSW, and this is facilitating their adaptation to a changing rural environment.     

Global and local policy forces for landscape perennialization in central North American agriculture

Farm production practices often focus on mitigating negative consequences of cropping – particularly annual crops like corn, cereals and oilseeds. Some of North America’s most-intensive farmlands are rapidly converting their remaining perennial cover to annual crops. While perennial cover like woodlands, grasslands and wetlands are valued for the many landscape services they provide, they are vulnerable to conversion to other cover types under drivers of landscape change. Conversions within farms constitute nuances rather than new land uses, yet landscape composition effects can be substantial when considering habitat, biodiversity, soil and water quality, carbon sequestration, and aesthetics. As the farm landscape becomes increasingly dominated by annual crop vegetation, the key drivers behind land cover types and management merit critical examination. This paper reviews recent studies on farmland composition and management in central Canada and the United States, identifying trajectories and magnitudes of landscape changes. To consider forces, both speculative examination of policies and information from farmer interviews help identify motivations for changes in perennial or annual proportions of farm landscapes. The paper concludes with forces that increase perennialization and existing or prospective pathways to improve the balance between annual and perennial vegetation.     

Avalanche prediction in Scotland: I. A survey of avalanche activity

Avalanches are a common occurrence throughout the Scottish Highlands and have been responsible for several injuries and deaths amongst climbers and ramblers. The paper describes approximately 1000 avalanches which have been recorded over the last 200 years, the majority being observed in the Cairngorms between the winters of 1977–1978 and 1979–1980. Many different types of avalanche have been recorded, including slab avalanches and loose snow avalanches. Although the majority are comparatively small, a small proportion are extremely large. These may travel over a mile and involve a snow layer up to two or three metres thick and 200–300 m wide. Excluding small-scale sluffing from free faces, most avalanches release from slopes between 35° and 45°. Avalanche activity occurs during many different types of weather conditions, including thaws, cold snaps, storms and calm conditions.     

Consequences of changed water management for Aboriginal Australians in the Murrumbidgee catchment,NSW

In the Murrumbidgee catchment of the Murray-Darling Basin, wetlands, rivers and other waterscapes are important features of Country for Aboriginal peoples. The Murrumbidgee River is the most heavily regulated river system in the Murray-Darling Basin. Discussion around the use of Murrumbidgee water is framed as a conflict between sustaining rural communities and using water to support ecological values, yet the voices of Aboriginal custodians are relatively unheard in this discussion. Using culturally important wetland plants as a starting point, this paper explores the understanding and perception of some Aboriginal people in relation to their Country and water. The grief of participants as they experience the degradation of their Country was palpable. The strong message that Country should be considered in its entirety—including ecological, social and cultural aspects—contrasts with current ownership and other institutional arrangements. Improving opportunities for communities and water managers to share knowledge and information, an openness to use Aboriginal wisdom, and careful ongoing management of environmental and cultural water have the potential to achieve positive cultural and ecological outcomes in the Murrumbidgee.     

Meteorological triggering scenarios of tree-ring-based snow avalanche occurrence on scree slopes in a maritime climate,Eastern Canada

ABSTRACT

Statistical relationships between weather conditions and the release of snow avalanches in the low-elevation coastal valleys of the northern Gaspé Peninsula are still poorly validated. As such, we explored climate–avalanche relationships through classification tree algorithms applied to tree-ring reconstructions of avalanche events. In order to assess the contribution of local factors on avalanche activity, avalanche regimes on east- and west-facing slopes were analyzed and compared. The results showed that avalanches on east-facing slopes appear to be primarily related to large cumulative snowfall in January, February, and March. On west-facing slopes, avalanches are mainly due to episodic snowfall and warming temperatures. However, both sides of the valleys showed the potential for the release of large avalanches in November and December, which is earlier than expected by the literature. Indeed, the weather variability at that time of the year (temperature oscillation around 0ºC) appears to favor the formation of an early, unstable snowpack and subsequent triggering of avalanches, such as the wet slab avalanche recorded by a time-lapse camera in November 2014. This camera provided a useful insight on the capacities of classification-tree models to link the yearly resolution of tree-ring data with weather triggers at different timescales.     

Functional analysis of landscape connectivity at the landscape,component, and patch levels: A case study of Minqing County,Fuzhou City,China

Maintaining forest landscape connectivity is one of the most effective ways to alleviate natural forest fragmentation and biodiversity loss problems. Recently, graph theory based metrics have been used as powerful tools in the assessment of landscape connectivity. However, the functional features of landscape units at different structure levels, based on which outcomes can be enriched and advice can be given for practical applications, have been overlooked. In this study, a series of graph-based connectivity indices was calculated to 1) evaluate the optimal threshold distance, 2) identify the key landscape units at the component and patch levels, and 3) classify the functional types of components and patches and analyze functional patterns at different structural levels. The relationship between patch size and patch functional performance in maintaining landscape connectivity was discussed. With a natural forest area in Minqing County of China as the study area, recommendations regarding forest conservation and connectivity enhancement were provided based on the research conclusions. This study provides a way to comprehensively analyze habitat fragmentation and functional patterns for local forest conservation.     

A method for delineating a hierarchically networked structure of urban landscape

We developed a new approach combining statistical and graphical methods to build a hierarchically networked structure for understanding spatial characteristics of urban landscapes at multiple scales. Natural breaks optimization algorithm is applied to determine the optimal number of urban land hierarchies and assign discrete patches into ordered sub-groups according to a selected geometric or functional attribute. Patches contained in a sub-group are linked to the patches in the next sub-group according to the spatial relationships between the patch centroids and Voronoi cells. The conceptual foundations and technical details of this approach are elaborated in the case study of building a hierarchically networked structure of urban built-up patches in Beijing. This approach can be applied to quantify landscape patterns of other land uses to facilitate assessments of interconnection between various types of land uses at varied hierarchical levels (spatial scales) and to evaluate ecological service functions of urban built infrastructures.     

Nitrogen mineralization potential in rewetted soils from a semi-arid stream landscape,north-west Australia

Drying-rewetting pulses stimulate nitrogen (N) mineralization in semi-arid systems and enhance N availability. Intermittent stream landscapes encompass a mosaic of soils of different textures and composition, and may support intense N transformation after rainfall. We modelled N mineralization potential by measuring accumulation of inorganic N (KCl extractable NO₃^? and NH₄⁺) in response to sustained flooding in soils from a small intermittent stream in semi-arid, north-west Australia. To test the relative importance of landscape position compared to flood pulse size, we incubated soils and sediments from six landscape positions, including three riparian vegetation types, rewetted to four different water potentials. Selected water potentials represented a light rain, heavy rain, single flood and successive flood event for the study site. The total amount of N mineralized was significantly affected by landscape position but not by saturation level. Riparian soils produced the greatest mineralization flush – over 70% of the total amount of N mineralized accumulated within 48 h of rewetting – however there was no difference among riparian vegetation types in N mineralization potential. N mineralized was a half to two-thirds lower in channel, floodplain and bank soils in comparison with riparian soils. We conclude that in systems subject to prolonged drought, N mineralization is predominantly determined by soil characteristics rather than the size of the rewetting pulse.     

Combining field and modelling techniques to assess rockfall dynamics on a protection forest hillslope in the European Alps

Adequate management of a mountain forest that protects downslope areas against impacts of rockfall requires insight into the dynamics of the hillslope environment. Therefore, we applied a combined approach, using field and modelling techniques, to assess the determining factors for rockfall source areas, rockfall tracks and rockfall runout zones on a forested slope in mountainous terrain. The first objective of this study was to understand why rockfall occurs in the study area. The second objective was to translate the knowledge obtained in the field into a model that simulates rockfall dynamics on a forested slope realistically. The third objective was to assess which hillslope characteristics primarily determine the distribution of active rockfall tracks. To achieve these objectives, we made a geomorphological map of the whole study area, and we measured the major discontinuity planes in the bedrock that are exposed in the rockfall source areas. Furthermore, a test site for simulation modelling within the larger study area was defined in which both a forest and a hillslope inventory were carried out. The available data and our developed rockfall simulation model allowed us to assess the slope characteristics that mainly determine the distribution of areas affected by rockfall. We found that in decreasing order of importance, both standing and felled trees, the surface roughness and rockfall resistant shrubs primarily determine the distribution of rockfall-affected areas. Simulation tests without a forest cover produced similar rockfall runout zones as fossil rockfall events identified in the field. We believe that the combined field and modelling approach is a prerequisite for understanding how forests can protect against rockfall.     

Discrimination of fluvial, eolian and neotectonic features in a low hilly landscape: A DEM-based morphotectonic analysis in the Central Pannonian Basin, Hungary

The Gödöllő Hills, a low-relief terrain within the Central Pannonian Basin in Hungary, is characterised by moderate tectonic deformation rates. Although typical tectonic landforms are not clearly recognisable in the study area, this paper succeeded in discriminating between tectonically controlled landforms and features shaped by fluvial erosion or deflation with no tectonic control.DEM-based morphometric parameters including elevation, slope and surface roughness, enabled the delineation of two NW–SE trending spearhead-shaped ridges separated by a wide rectilinear valley of the same strike. Although directional statistics suggested possible tectonic control of NW–SE striking landforms, precise morphometry completed with an analysis of subsurface structures rejected their tectonic preformation. Deflation plays a significant role in shaping the area, and the presence of two large-scale yardangs separated by a wind channel is proposed. In temperate-continental areas of Europe, no deflational landforms of such scale have been described so far, suggesting that Pleistocene wind power in periglacial areas was more significant than it was previously thought.Characteristic drainage patterns and longitudinal valley profiles enabled the recognition of areas probably affected by neotectonic deformation. A good agreement was observed between locations of Quaternary warping predicted by the morphometric study and subsurface structures revealed by the tectonic analysis. Zones of surface uplift and subsidence corresponded to anticlinal and synclinal hinges of fault-related folds. In low-relief and slowly-deforming areas, where exogenous forces may override tectonic deformation, only the integrated application of morphometric and subsurface-structural indications could assure correct interpretation of the origin of various landforms, while a morphometric study alone could have led to misinterpretation of some morphometric indices apparently suggesting tectonic preformation. On the other hand, the described morphological expression of subsurface structures could verify Quaternary age of the deformation.