Clumps Of Trees Research Articles

Basic features of a group selection system modification aimed to sustian regular-uneven-aged stand structure

Proposed modification of group selection system is aimed to successfully combine its elements with biological peculiarities (such as sympodial growth, distinct heliotropism and crown growth plasticity, heavy seeds and difficult dissemination, etc.) of shade-intolerant and mid-tolerant tree species, stands of which may be managed under the same system. Principles, on which the modification is based, are: (i) application of well founded extended rotations in order to increase the proportion of tree groups above 90-100 years age in the stand, where upon the height increment and crown side spread by most of the main tree species in Bulgary drop to considerably lower level, and (ii) optimum systematic spatial positioning of openings in the stand canopy (and tree groups respectively) over the stand area, so that new gaps created by consecutive selection cuttings adjoin to a minimum number of middle aged (40-80 y. age) tree groups. Such clumps of vigorous trees with high growth rates, heliotropism and plasticity carry certain risks of spoiling the target regular-unevenaged stand structure. Factors of significance are discussed by determining the rotation age, size of gaps opened in the stand canopy, selection cutting cycle, a regularuneven- aged stand structure design and the minimum area that enables realisation of full selection system cycle. Definitions and determination of selection system elements in their mutual connections are presented in consecutive steps when designing a particular application of group selection system for exemplary pure stand of common beech (Fagus sylvatica L.). By the proposed group selection system modification the amount of combinations of various factors having impact upon processes in the tree groups are diminished compared to that by random spatial arrangement of the gaps over the stand area. Silvicultural activities aimed to maintain a stable unevenaged stand structures are thus getting more predictable, easier to schedule and efficient.

Assessment of tree layer biomass and structure using aerial photos in lake catchments of the Šumava Mts.

The combination of georeferenced colour aerial photos and limited field measurements of individual trees was used to determine tree stand biomass in forests of prevailing Norway spruce. The technique was carried out in two localities – small catchments of natural lakes in the Bohemian Forest (56 and 76 ha in size, respectively). This method is not so expansive as the inventory based on sample plots, namely in the terrain of high dynamics in the mountains. Tree crown diameters were determined semi-automatically on the basis of orthophotos. The catchment of Plešné jezero Lake can be described by these average values: crown diameter 4.5 ± 1.35 m, mean tree height varying between 19.6 and 30.2 m depending on altitude (tree average and standard deviation are 25.5 ± 3.9 m), tree density 154 ± 67.7 ha and stand biomass 197 t/ha. The Čertovo jezero Lake catchment shows somewhat different values: crown diameter 4.9 ± 1.35 m, mean tree height varying between 20.9 and 25.1 m (dependence on altitude is weak; tree average and standard deviation are 25.6 ± 2.0 m), tree density 200 ± 65.7 ha (all parameters for Norway spruce only), and stand biomass 156 t/ha (Norway spruce) + 17 t/ha (European beech). Some features are common to both catchments: a regular to random tree pattern prevails. Tree clumping is typical of the most extreme stands. Minimum tree density occurs in the zone of the altitudes 1,200–1,250 m a.s.l. The crown diameter to dbh ratio is independent of altitude. Tree height decreases linearly with altitude. The distribution of trees according to crown diameter is skewed to higher values.

Spatial structure of alpine trees in Mountain Baima Xueshan on the southeast Tibetan Plateau

Most of the trees at treeline on the Tibetan Plateau are endemic to the Plateau. Yet little is known about these species. The study focused on the population structure, spatial patterns and associations of the treeline species Abies forestii var. georgei and Juniperus saltuaria at treeline and timberline in Mountain Baima Xueshan on the southeast Tibetan Plateau. These species form monodominant communities on the north- and south-facing slopes, respectively. Stem density, DBH-distribution, distribution pattern of different tree size classes, and intraspecific spatial association between different tree size classes of both species were analyzed. Spatial structure varied between A. forestii var. georgei and J. saltuaria, and for the same species, the spatial structures were also different from timberline to treeline. Stem density, mean tree height and young individuals of A. forestii var. georgei were significantly higher than those of J. saltuaria. For the same species, they were different from timberline to treeline, i.e., stem density and mean tree height of both species became lower. Size classes of both species were mainly clustered either at treeline or at timberline but at different scales, and spatial patterns of young J. saltuaria were mainly dominated by random patterns. Clumps of trees created more favorable microenvironments in harsh environments at treeline and timberline. Most tree size classes showed positive intraspecific spatial associations, but positive associations between size classes of J. saltuaria were not as significant as those of A. forestii var. georgei. The south-facing slope was usually subjected to varying intensities of pastoralism. Livestock disturbance greatly changed the microhabitat and reduced the number of young individuals. The potential of trees to regenerate was greatly inhibited, while A. forestii var. georgei showed greater regeneration potential. Spatial structures of J. saltuaria were also modified by this kind of human impact.

Can stable carbon isotopes (δ13C) in soil carbon be used to describe the dynamics of Eucalyptus savanna-rainforest boundaries in the Australian monsoon tropics?

The history of isolated patches of monsoon rainforest within large tracts of Eucalyptus savanna is poorly understood because of the scarcity of reliable palaeoecological records in the Australian monsoon tropics. Elsewhere in the world, the ratio of the stable isotopes 13C to 12C (δ13C) in soil organic matter has shed light on the dynamics of rainforest–savanna boundaries because tropical grasses with the C4 photosynthetic pathway have a distinct δ13C signature (–17 to –9‰) compared with that of woody plants with the C3 photosynthetic pathway (–32 to –22‰). In order to determine the magnitude of the variation in δ13C, unreplicated soil profiles were sampled beneath different vegetation types on three boundaries between Eucalyptus savanna and rainforest that were both growing on Tertiary age laterite parent material. Replicated (n = 3) soil profiles, which were also derived from Tertiary age laterite, were sampled from beneath: (i) dense stands of African grasses within a frequently burnt Eucalyptus savanna; and within the same long unburnt Eucalyptus savanna, (ii) patches of African and natives grasses and (iii) clumps of Acacia trees. The strongly negative δ13C values of soil organic matter derived from the frequently burnt and long unburnt grassy understoreys in the Eucalyptus savannas showed that a considerable amount of the soil carbon was derived from C3 (woody) species despite the presence of a ground layer dominated by C4 grasses. However, a feature of these data was the considerable variability among the three ‘replicate’ profiles. The surface soil samples from beneath three clumps of Acacia trees in the unburnt Eucalyptus savanna had much less variable δ13C values and were similar to two of the three monsoon rainforests sampled. The pattern of δ13C values from unreplicated soil profiles from different vegetation types across three rainforest boundaries was also very variable and not always obviously related the known disturbance history of the extant vegetation. Given the considerable variability within and between vegetation types with contrasting disturbance histories, it is concluded that the use of carbon stable isotopes to advance understanding of the dynamics of rainforest and Eucalyptus savanna boundaries will require further development, such as determination of the 14C age and δ13C values of different soil carbon fractions.

Edge geometry influences patch-level habitat use by an edge specialist in south-eastern Australia

We investigated patterns in habitat use by the noisy miner (Manorina melanocephala) along farmland-woodland edges of large patches of remnant vegetation (>300 ha) in the highly fragmented box-ironbark woodlands and forests of central Victoria, Australia. Noisy miners exclude small birds from their territories, and are considered a significant threat to woodland bird communities in the study region. Seventeen different characteristics of edge habitat were recorded, together with the detection or non-detection of noisy miners along 129 500-m segments of patch edge. Habitat characteristics ranged from patch-level factors related to patch-edge geometry to site-level floristic factors. Backward (stepwise) logistic regression analyses were used to identify habitat characteristics that were associated with the occupancy of a site by noisy miners. After accounting for the effects of spatial autocorrelation on the occurrence of noisy miners along edges, we identified projections of remnant vegetation from the patch edge into the agricultural matrix (e.g., corners of patches, peninsulas of vegetation) and clumps of trees in the agricultural matrix within 100 m of the edge as significant predictors of the occupancy of edges by noisy miners. This relationship was also confirmed in two other geographically and floristically distinct habitats within Victoria. The use of edges with projections by noisy miners may confer advantages in interspecific territorial defence. In light of these results, we advocate revegetation strategies that attempt to enclose projections within 100 m of the edge, with fencing placed out to this new boundary, to reduce the likelihood of colonisation and domination of an edge by noisy miners. Our study highlights the need for greater consideration to be given to the patterns in habitat use by aggressive edge specialists, particularly in relation to patch-edge geometry and other human-induced components of landscapes.

Does forest structure affect reproduction of northern goshawks in ponderosa pine forests?

Summary Many management prescriptions are based on ecological hypotheses; evaluating empirical support for these hypotheses can improve management. There has been considerable dispute about the potential response of the northern goshawk to three management‐driven forest structures in ponderosa pine forests of the south‐western United States: (i) the structure recommended by US Forest Service's goshawk guidelines, designed to increase the abundance of 14 goshawk prey species and thus benefit goshawks; (ii) preferred foraging habitat as suggested by empirical evidence that goshawks forage selectively in areas with abundant large trees and dense canopy closure, rather than areas of highest prey abundance; and (iii) presettlement (i.e. prior to Euro‐American settlement) structure characterized by clumps of large trees, canopy closure < 40% and dense herbaceous understorey, which could have negative effects on goshawks. To evaluate empirical support for hypotheses that goshawk reproduction is affected by each of these three forest structures, we measured forest structure in a 1215‐ha nest‐centred circular area in each of 13 goshawk breeding areas on the Apache–Sitgreaves National Forest, Arizona. The breeding areas were selected to span the full range of productivity (fledglings per year monitored) over the previous 9‐year period. Forest structure had a moderate effect on goshawk productivity (r2 ≤ 0·46). Contrary to expectation, goshawk productivity decreased with increasing similarity to the goshawk guidelines. Goshawk reproduction was not correlated with resemblance of the breeding area to preferred foraging habitat or resemblance to presettlement forest conditions. Synthesis and applications. Because the goshawk guidelines may not improve goshawk reproduction, the Forest Service should reconsider its decision to apply the guidelines to most forested lands in Arizona and New Mexico. Managers should evaluate empirical support routinely for the major ecological hypotheses that underlie forest prescriptions.

Restoring plant species diversity and community composition in a ponderosa pine-bunchgrass ecosystem

Monitoring of ecological restoration treatments often focuses on changes in community structure and function. We suggest that long-term changes in community composition also need to be explicitly considered when evaluating the success of restoration treatments. In 1992, we initiated an experiment in a ponderosa pine-bunchgrass ecosystem to evaluate responses to restoration treatments: (a) thinning the overstory vegetation (‘thinning’), (b) thinning plus forest floor manipulation with periodic prescribed burning (‘composite’), and (c) untreated ‘control.’ Treatments were further stratified by forest patch type: presettlement tree clumps (trees that established prior to the onset of fire exclusion in 1876), patches of retained postsettlement trees, patches where all postsettlement trees were removed, and remnant grass openings. Species richness did not differ among treatments for 10 years, but was highest in the composite treatment in 11th and 12th year after initial treatment. Community composition diverged among treatments 5 years after initial treatment, and compositional changes were greatest in the composite treatment. Species richness and composition differed among patch types prior to treatment. Remnant grass patches were the most diverse and presettlement patches were the least diverse. Following treatment, species richness in the postsettlement removed and retained patches, gradually approached levels found in remnant grass patches. Compositional differences among patch types changed a little by 2005. Species richness at the 2 m2 scale increased only where the overstory was thinned and the understory was burned. However, these changes may not be detectable for many years, and can vary temporally in response to events such as severe droughts. Nonnative species establishment may be reduced by scheduling longer burn intervals or by refraining from burning where fuel loads are not hazardous, though these options may hinder goals of increasing diversity. Restoring species diversity and community composition continues to be more difficult than restoring ecosystem structure and function.

Changing scale in ecological modelling: A bottom up approach with an individual based vegetation model

Net primary production (NPP) depends crucially on the sun radiation absorption, and hence its prediction on the modelling of the radiation. In heterogeneous systems such as savannas, the photosynthetically active radiation (PAR) absorption is more difficult to predict than in homogeneous systems, due to the presence of tree clumps and open grass areas. Using a detailed 3D model, we propose new formulations of PAR absorption derived from the Beer–Lambert law for heterogeneous vegetation. To account for intra-plot vegetation heterogeneity we assume an intra-plot partition of space into two or three zones, based on tree location. We develop two models derived model from the Beer–Lambert law: (1) a simple partition of space below and outside trees, (2) a partition in three zones, including the tree shading area. The only model to predict PAR interception for all types of spatial patterns was the most complex one (including tree + tree shading zone + open grass areas). In this model, extinction coefficients can be derived from vegetation structural parameters like tree cover, and tree shading area. Tree shading area could be computed from geometric site parameters (latitude, longitude, tree height). With increasing satellite resolution it can be possible to obtain these structural parameters of vegetation (cover, overlap, tree height) needed by this Beer–Lambert derived model. Such an absorption model could then be used as a basis for a Monteith-style model of vegetation functioning for heterogeneous vegetation.

Recent surveys for Bursaphelenchus xylophilus in the Czech Republic1

The State Phytosanitary Administration of the Czech Republic (SPA) conducted a survey of Bursaphelenchus xylophilus in 2004 and 2005. In 2004 97 locations were surveyed and 60 samples were taken. B. xylophilus was not found in any of the samples. In 2005, the SPA performed 120 phytosanitary inspections on solitary conifers, and in forest stands and clumps of trees. Checks were performed on Pinus sylvestris and Pinus nigra trees and in coniferous woodland mainly in areas at risk of invasion from B. xylophilus. Of 70 phytosanitary inspections performed in at risk areas, 13 samples were taken for laboratory processing and analysis. Fifty phytosanitary inspections were carried out outside risk areas, mainly in forests and parks, and 28 samples were taken. The Czech University of Agriculture in Prague together with the diagnostic laboratory of the SPA carried out a second survey in 2005. Fifty‐eight samples were taken from 58 surveyed locations in forests where coniferous trees with symptoms had been found. Laboratories performed a survey of B. xylophilus vectors to find only one vector species, Monochamus galloprovincialis subsp. pistor. In total in 2005, 178 phytosanitary inspections were carried out in the Czech Republic. B. xylophilus was not detected in either samples or vectors. Thus the results of the surveying were negative in both 2004 and 2005. The status of Bursaphelenchus xylophilus in the Czech Republic is: absent, confirmed by survey.

Tree dynamics in canopy gaps in old-growth forests of Nothofagus pumilio in Southern Chile

The gap dynamics of two Nothofagus pumilio lenga stands have been investigated. We evaluated and compared tree diameter distributions, spatial patterns, tree fall and gap characteristics and regeneration responses in gaps in two old-growth forests of Nothofagus pumilio in Southern Chile Shangri-La: 36°60' S, 71°30' W; Reserva Coyhaique: 45°52' S, 72°00' W. In addition, we describe relationships between gap size and regeneration characteristics. We detected some differences in tree and sapling densities between sites. The causes of gap formation and the gap size distribution, mean gap area, and gap fraction were similar, but gap abundance was different at the two sites. The Reserva Coyhaique site had 15 gaps/ha compared to 10 gaps/ha for Shangri-La. Sizes of clumps of trees were within the range of sizes of canopy gaps at both sites. The density of saplings was higher in gaps than under closed forest at R. Coyhaique, but not at Shangri-La. We found that sapling densities were unrelated to gap size in both sites. The lower sapling density in gaps at Shangri-La might be explained by the presence of Chusquea quila, a competitive pioneer bamboo species. The height increment was related to gap size at ShangriLa, but not at R. Coyhaique. Gap size itself does not account for all the variation in recruitment performance in these Southern beech stands.

Modeling seed dispersal in a variable environment: a case study of the fleshy-fruited savanna shrub Grewia flava

In ecology much attention has been paid towards seed dispersal of fleshy-fruited plants, however, knowledge is lacking about the long-term demographic consequences of variation in dispersal distance and fruit removal rate, particularly given the natural variability of the environment the organism lives in. In this study we used a spatially explicit, two-level stochastic computer model to simulate population dynamics of a fleshy-fruited shrub living in the sub-canopy of solitary savanna trees. On the landscape level we implemented three realistic scenarios of savanna landscape dynamics for a period of 500 years with equal inter-annual mean of environmental variables. The first scenario is representative of a relatively constant environment with normal variability in precipitation, constant tree density and random tree recruitment pattern. The second and third scenarios represent positive auto-correlated, cyclic patterns with alternating phases of tree cover increase and decrease corresponding with favorable and unfavorable rain phases. Our simulation experiments show that when fruit removal rate is extremely low, population persistence is enhanced under relatively constant rain conditions, while alternating rain phases of the cyclic scenarios lead to a significant population decrease. This result confirms previous findings that periodically fluctuating environments may increase local extinction risk. However, when dispersal distance is a limiting factor (whilst removal rate was sufficiently high), tree clumps typically forming in wet phases of both cyclic scenarios compensated for the negative effect of low dispersal distances, while the constant scenario with random tree pattern and larger inter-tree distances resulted in a significant population decline.

Distribution and stand structure of Taxus baccata populations in Greece; Results of the first national inventory

Yew, Taxus baccata L. is a declining species that occupies a limited range throughout the Mediterranean basin. The community structure and spatial distribution of yew trees were investigated in Greece by means of a questionnaire survey administered to Forest District Offices nationwide. The results of the survey show that the species population is confined mainly to mountainous areas extending from south Peloponnese to Evros prefecture. Findings suggest yew as a rare and potentially endangered species that occurs at different degrees of population fragmentation ranging from individual trees to more rarely clumps of trees. Yew distribution is formed by isolated populations, mostly in mountain ravines at an altitudinal range between 500 and 1 500 metres ; it increasingly becomes an isolated storey tree within fir pure forests (Abies cephalonica) and various kinds of mixed woodlands of beech and oak, as well as mixed forests of fir and beech. Populations are small , most in shrubby groups of 5 to 50 individuals with height ranging between 3 and 6 metres and low proportion of saplings and seedlings. The rarity of yew populations and biochemical interest implicate the adoption of appropriate management actions to facilitate broader expansion, aiming at restoring existing Taxus woodland areas and increasing the share of Taxus forests under statutory protection within the Natura 2000 network of protected areas.

Colony structure in a plant-ant: behavioural, chemical and genetic study of polydomy in Cataulacus mckeyi (Myrmicinae).

Social organisation of colonies of obligate plant-ants can affect their interaction with myrmecophyte hosts and with other ants competing for the resources they offer. An important parameter of social organisation is whether nest sites of a colony include one or several host individuals. We determined colony boundaries in a plant-ant associated with the rainforest understorey tree Leonardoxa africana subsp. africana, found in coastal forests of Cameroon (Central Africa). This myrmecophyte is strictly associated with two ants, Petalomyrmex phylax and Cataulacus mckeyi. Plants provide food and nesting sites for P. phylax, which protects young leaves against insect herbivores. This mutualism is often parasitised by C. mckeyi, which uses but does not protect the host. The presence of C. mckeyi on a tree excludes the mutualistic ant. Because Petalomyrmex-occupied trees are better protected, their growth and survival are superior to those of Cataulacus-occupied trees, giving P. phylax an advantage in occupation of nest sites. C. mckeyi often colonises trees that have lost their initial associate P. phylax, as a result of injury to the tree caused by disturbance. Polydomy may allow C. mckeyi to occupy small clumps of trees, without the necessity of claustral colony foundation in each tree. Investigating both the proximate (behavioural repertoire, colony odour) and the ultimate factors (genetic structure) that may influence colony closure, we precisely defined colony boundaries. We show that colonies of C. mckeyi are monogynous and facultatively polydomous, i.e. a colony occupies one to several Leonardoxa trees. Workers do not produce males. Thus, the hypothesis that polydomy allows workers in queenless nests to evade queen control for their reproduction is not supported in this instance. This particular colony structure may confer on C. mckeyi an advantage in short-distance dispersal, and this could help explain its persistence within the dynamic Leonardoxa system.

On Surveying the Whole Legal Forest

I am always amazed by newspaper reports of the way that geologists and space scientists draw complex conclusions about the origin or nature of a planet from data sent back by a probe of one tiny part of the planet's surface. They seem to have a lot of confidence in their underlying theories. The same is not true for sociolegal scholars. We don't have full-fledged theories about how legal systems actually work, and hence it seems risky to make big generalizations about a system as a whole based on a study of one or two legal institutions or processes. Making generalizations about the in action for whole legal systems is especially risky if the subject is the United States, with its 50 different state legal systems, from Mississippi to Montana to Massachusetts, and with its proliferation of different kinds of courts, law enforcement bodies, police departments, administrative tribunals, and regulatory agencies, state, federal and local. Small wonder that most empirical sociolegal scholarship is relatively narrowly focused on specific legal policy areas and processes. While these case studies are immensely valuable, occasionally it seems worthwhile to use the scholarly close-ups of particular clumps of trees to draw some wide-angle conclusions, however tentative, about the shape and dynamics of the legal forest. That, however quixotic the effort, is what I sought to do in Adversarial Legalism: The American Way of Law (hereinafter AL). But just as Don Quixote needed the skeptical realism of Sancho Panza, the essays on AL in this issue, paying close attention to text, empirical detail, and analytic precision, serve as a reminder of the pitfalls attending the quest for generality. Yet I am not quite willing to don the Quixote costume. In this essay I will argue that AL, even if a bit ambitious, is reasonably realistic, and that the questions raised by the other essays raise meaningful but not

Territoriality and singing-site preferences in the cricket, Cyphoderris monstrosa (Orthoptera: Haglidae) in western North America

Many male orthopterans prefer to stridulate from certain microhabitats. However, it is unknown if such preferences exist in Cyphoderris monstrosa Uhler (Haglidae). Choice tests indicated that C. monstrosa strongly prefer to sing from large trees and clumps of trees, but a survey of singing C. monstrosa suggested indifference to tree species. The observed preferences may have implications for understanding the evolution of territoriality in C. monstrosa.

Population density and species composition changes for breeding bird species in farmland woodlots in western Poland between 1964 and 1994

Intensive farming practices can impact on bird species richness and density. The paper analyses long-term changes in the breeding avifauna of small mid-field woodlots (avenues, shelterbelts and tree clumps) in intensively used farmland in Wielkopolska region (western Poland). It is the only set of data allowing the analysis of long-term trends in bird breeding in the Polish agricultural landscape. The estimation of population density was done with the mapping method in three periods: 1964–1966, 1984 and 1991–1994. Since 1960 farming systems in Wielkopolska have been strongly intensified: e.g. the yield of wheat ( Triticum sp.) have risen from 2 to 5 Mg ha −1 and the number of tractors per 100 ha from 0.5 to 8. The number of breeding species was found to have increased from 44 in the 1960s to 51 in the 1990s. Total density of breeding birds was lower only in woodlots where trees had been cut before 1990s, remaining unchanged in other woodlots (at 23–24 pairs ha −1). However, there has been a significant decrease in number of some ‘farmland specialists’ like Corn Bunting ( Miliaria calandra) and Ortolan Bunting ( Emberiza hortulana), while a slight increase occurred in the group of species linked with wood habitat. Although species number and population density of birds breeding in farmland woodlots have changed only slightly in the study area, the population trend analysis suggests that even moderately intensified agriculture (by EU standards) affects the community of birds.

Regeneration and stand dynamics of Fitzroya cupressoides (Cupressaceae) forests of southern Chile’s Central Depression

Several populations of Fitzroya cupressoides (Mol.) Johnst. (Cupressaceae, common name “alerce”), a threatened, long-lived conifer endemic to southern Chile and parts of Argentina, have recently been found in Chile’s Central Depression, where the species was thought to have been extirpated. The objective of this study was to determine, on eight sites in the Depression, Fitzroya’s regeneration behavior in relation to disturbance, its substrate and cover requirements for establishment, and whether regeneration is by seed or vegetative means. This objective required inspection of tree age-class distributions, analyses of microsite conditions and spatial distributions of Fitzroya individuals, and genetic analysis of Fitzroya trees using random amplified polymorphic DNA (RAPD) analysis. Age-class distributions indicated a “catastrophic” regeneration mode, in which seedling establishment follows stand-devastating disturbance, such as fire. Regeneration was both by seed and vegetative means (root sucker sprouting and layering), although overall, vegetative reproduction was more prevalent (63% of all regeneration). Regeneration from seed occurred primarily under open canopies (<40% cover) and on substrates of humus, moss beds, and coarse woody debris. Spatial analyses revealed clumping at various scales for Fitzroya seedlings, saplings, and trees. Several obvious clumps of trees were assumed to be sucker sprouts from cut stumps; however, RAPD analyses indicated they were of seed origin. Such clumping is likely due to the patchy co-occurrence of appropriate substrates and canopy covers. Despite substantial environmental differences between the Central Depression and the portions of the Coastal and Andean Cordilleras where Fitzroya is found, populations in all three regions show striking similarities in their regeneration and stand dynamics. Fitzroya’s longevity and at times abundant regeneration provide the biological basis for its persistence in Chile’s Central Depression.

A gift of benevolence

They landed in small boats and waded ashore. They had one set of surgical instruments, a suction machine, an electrocautery unit, and an anesthesia pocket kit. The countryside resembled the Midwest in many ways with crops, gentle rolling hills, and clumps of trees, except for the tiled roof huts. The roads were very narrow, rough, and dusty. There was a small railroad with wobbly rails winding over hills. It was April 1945, and they had landed on Okinawa, an island that was approximately 60 miles long and 8 miles wide. A terrible bombing had just occurred prior to their coming ashore. There were craters all over the island. There was a large seawall which was designed to protect the coast from invasion but now often acted as a place to go and hide from bombing raids. An operating-room tent was finally completed. The rain came and soaked the area ankle deep in mud down the middle of the ward tent. And then there were the casualties. All night they kept pouring in. New faces, new names. The grinding of the low-geared ambulances, the rush of the litter-bearers, and the pale, frightened faces of the wounded in the lantern light. Spinal taps being done by flashlight with a pouring storm and a crowded ward. It was during one of those long nights that a young, severely wounded Japanese soldier was brought into the American hospital tent. He was shaking, scared, in shock, and prepared to die at the hand of the enemy as he had been taught would happen if captured. The American surgeon did not hesitate, but had the soldier brought into the operating room and there, through a translator, explained the need for a bilateral amputation to save his life. His legs were hopelessly injured. The soldier was disbelieving and cried out to be killed. With time and discussion with the translator, consent was obtained and the operation performed. The next morning, the soldier was missing from his bed and was discovered to have crawled the length of the hospital tent to hold the feet and embrace the doctor who had saved his life. The doctor, in turn, embraced him, and both men suddenly cried with new-found joy. It was the beginning of a new day: enemies turned into friends by a spontaneous act of compassion.

Nest predation in and adjacent to cutblocks with variable tree retention

Partial harvesting, or the retention of live trees in cutblocks, is thought to reduce the impacts of clearcutting on wildlife biodiversity. An unintended biproduct of this practice may be an increase in nest predation in and adjacent to these cutblocks. We examined patterns of predation on artificial ground and shrub nests in and adjacent to stands where varying amounts of trees were left after harvesting in Alberta’s boreal mixed-wood forest. We placed nests in old, aspen-dominated stands adjacent to 3-year-old cutblocks with high (86–133 trees/ha), intermediate (48–55 trees/ha), and low (10–36 trees/ha) residual tree retention, and in forested controls (246–414 trees/ha). In a second experiment, we placed nests in residual tree clumps in high and intermediate retention cutblocks and in forested controls. Each nest contained one painted plasticine and one Chinese Painted Quail ( Coturnix chinensis) egg and predators were identified based on marks left in plasticine eggs. Vegetation structure and composition and overhead and lateral cover were measured around each nest. Data were analysed with a nested logistic regression approach, using generalized linear models with quasi-likelihood functions to analyse nest predation with respect to treatment and vegetation characteristics around the nest. In both experiments the identified nest predators were murid rodents, red squirrels ( Tamiascurus hudsonicus) and birds. Nests closer to the ground were more likely to be depredated. Nest predation was not related to the level of residual tree retention in either experiment nor to the size of residual tree clumps in the second experiment. Vegetative cover at the nest did not enter explanatory models, nor did most measures of vegetation structure and composition around the nest. The few vegetation factors that did enter models were not consistent between experiments and generally the models had low predictive power. We conclude that, within 3 years postharvest, elevated nest predation did not occur in tree-retention cutblocks when compared to unharvested forests, nor in high (compared with low and intermediate) tree-retention cutblocks.

Effect of long-term exclusion of fire and herbivory on the soils and vegetation of sour grassland

The effect of long-term exclusion of fire and herbivory, as mediated by aspect, on soils and the structure, composition, and diversity of vegetation was investigated in Döhne Sourveld (34 years), Piet-Retief Sourveld (45 years) and Southern Tall Grassveld (49 years). Exclusion had no effect on the soil chemistry of the surface 15 cm of soil in Dohne and Piet Retief Sourveld. Exclusion promoted the ingress of woody elements, including heath-like species, but the extent of ingress was related to water availability (rainfall, aspect), proximity of propagules, duration of protection, and accidental fires. Alien invasive woody species, in particular Acacia mearnsii established at all sites. Woody species were mostly bird- or wind dispersed, some had no known nearby population, although some Acacia species were herbivore-dispersed. The wettest grassland, Piet Retief Sourveld on a southern aspect, was transformed to a shrubland matrix (mainly Helichrysum splendidum) with tree clumps of forest precursor species (Rhus dentata, Halleria lucida, Myrsine africana, Buddleja salviifolia, Leucosidea sericea) and A. mearnsii. A species-rich grassland on the northern aspect had become dominated by tall Hyparrhenia rufa, with scattered shrubs of L. sericea and Helichrysum rogulosum. The southern aspect exclosure in Döhne Sourveld had developed an A. mearnsii - B. salviifolia savanna, with Cymbopogon excavatus, Themeda triandra and Tristachya leucothrix as common grasses. The northern aspect exclosure on Döhne Sourveld maintained a grassland character, although heath-like elements (Stoebe vulgaris, Erica aspalanthifolia) established. Protection of the Southern Tall Grassveld promoted an open savanna of exotic and indigenous Acacia and broadleaf species, an increase in life forms including the succulent Aloe maculata, and the transformation of a T. triandra - T. leucothrix sward to an Aristida junciformis sward. Ferns benefitted from exclusion of fire and herbivory. Fire and herbivory rather than soil properties would seem the primary determinants of the structure of sour grasslands.