Vine Density Research Articles

The extent and impact of exotic vine invasions in fragmented mesic forests in Eastern Australia

AbstractExotic vines threaten biodiversity causing damage to forest structure. We investigated the distribution of exotic vines across different patchily distributed plant communities. We surveyed patches of 12 threatened, mesic forest communities along the coastal plain in New South Wales, Australia to determine how exotic and native vine distribution and density were influenced by characteristics of forest patches and neighbouring land use. Vine density and stem widths were measured in quadrats in the edge and interior of patches. Canopy cover, number of dead trees, area to perimeter ratio and surrounding land use were recorded for each patch. Our results show that exotic vine assemblages were influenced by anthropogenic land use surrounding patches but not influenced by community type. Most exotic vine species were present across the whole region where surveys were undertaken. Exotic vines species were sometimes at high densities but had smaller stem widths than native species and there was no change in density from the edges into the interior. Araujia sericifera and Ipomoea cairica were the most prevalent exotic species and together with the fast edge growing Anredera cordifolia are of key concern. In contrast, native vine assemblages were species rich, with some individuals having large stem widths suggesting greater age and we found species composition varied with plant community type. Native vines showed continual recruitment and appeared more specialized to the attributes of each plant community. Surrounding anthropogenic land uses (residential, agricultural and industrial) were the most important factors predicting invasion of exotic vines and were more important than the length of edges. This suggests that the surrounding matrix characteristics were influencing degradation of the interior of these patches, rather than exotic vines invading along an invasion front from the edge. Exotic vines need to be controlled across the entirety of patches, rather than a focus on edge control practices.

Long-term interactive impacts of the invasive shrub Lonicera maackii and white-tailed deer (Odocoileus virginianus) on a deciduous forest understory

AbstractWhite-tailed deer (Odocoileus virginianus) (hereafter, ‘deer’) and invasive plants affect forest understories, but few studies have investigated their interaction. We investigated long-term (11-yr) effects of excluding deer and removing the invasive shrub, Amur honeysuckle [Lonicera maackii (Rupr.) Herder], on plants in southwest Ohio. Deer exclusion enhanced tree seedling richness and density, but reduced annual and bare ground cover. Vine density was reduced by Lonicera, especially where deer were excluded. Seedlings of several tree species, the invasive shrub, burning bush [Euonymus alatus (Thunb.) Siebold], and the invasive vine, winter creeper [Euonymous fortunei (Turcz.) Hand.-Maz.], were indicator species of the deer exclosure by Lonicera removal treatment combination. The effect of deer on cover of native species depended on Lonicera treatment: where shrubs were removed, cover was higher where deer were excluded, but where shrubs were present, cover was higher where deer had access. We attribute these interactions to the reduced growth of, and shading by, Lonicera where deer had access and browsed this invasive shrub. Some of these effects were evident in the first 6 yr, but are now larger. Other effects were not evident in the earlier evaluation. These findings inform management of areas with high densities of deer and invasive shrubs palatable to deer. Control of only invasive shrubs will reduce native cover and not improve tree regeneration. Managing only deer will increase woody plants but reduce native cover. Management of both stressors is needed to promote tree regeneration and restoration of plant communities.

A comparative study on training systems and vine density in Santorini Island: Physiological, microclimate, yield and quality attributes

The Mediterranean basin is regarded as one of the most affected global regions by climate change. Traditionally, viticulture in this region copes with high temperatures, heat waves and drought. Such extreme conditions are expected to intensify due to climate change in the future. Our study focuses on the viticulture of Santorini Island, located in South Aegean (Greece). Local varieties trained with the traditional ‘Kouloura’ training system have been cultivated for thousands of years on the island, producing recognised high-quality PDO wines worldwide. The literature on these traditional training systems is scarce, and their investigation could aid in the adaptation of viticulture to hotter and drier future climatic conditions. The objective of this study was to compare the physiological and agronomic response of Assyrtiko grapevines to the traditional training systems ‘Kouloura’ and VSP training system over two growing seasons and to establish the factors influencing the performance of each system in the semi-arid conditions of Santorini Island. In brief, the ‘Kouloura’ training system maintained a less-stressed water status compared to VSP, while for both studied years during ‘Kouloura’ exhibited significantly higher photosynthetic rates and stomatal conductance. Regarding microclimate observations, we found that, especially during heatwaves, VSP’s grapes were more exposed to higher temperatures during midday than ‘Kouloura’ and that the ‘Kouloura’ system protected against damage from heatwaves and strong winds when compared to VSP. Investigating the mechanisms by which these traditional training systems are adapted to hot, dry climatic conditions creates applicable knowledge for developing and using alternative training systems in similar environments to adapt to climate change.

Win-win opportunities combining high yields with high multi-taxa biodiversity in tropical agroforestry

Resolving ecological-economic trade-offs between biodiversity and yields is a key challenge when addressing the biodiversity crisis in tropical agricultural landscapes. Here, we focused on the relation between seven different taxa (trees, herbaceous plants, birds, amphibians, reptiles, butterflies, and ants) and yields in vanilla agroforests in Madagascar. Agroforests established in forests supported overall 23% fewer species and 47% fewer endemic species than old-growth forests, and 14% fewer endemic species than forest fragments. In contrast, agroforests established on fallows had overall 12% more species and 38% more endemic species than fallows. While yields increased with vanilla vine density and length, non-yield related variables largely determined biodiversity. Nonetheless, trade-offs existed between yields and butterflies as well as reptiles. Vanilla yields were generally unrelated to richness of trees, herbaceous plants, birds, amphibians, reptiles, and ants, opening up possibilities for conservation outside of protected areas and restoring degraded land to benefit farmers and biodiversity alike.

Allometric equations for the invasive vine air potato (Dioscorea bulbifera) in its exotic range in Florida

AbstractNondestructive means for estimating air potato (also known as air yam; Dioscorea bulbifera L.) biomass will help gauge its management efficacy over time. We developed allometric equations to estimate total and fractional biomass components and densities of aerial bulbils and underground tubers of field-grown D. bulbifera in Florida. We selected four naturally infested sites representing its southern, central, and northern distribution in Florida and measured three independent variables (vine densities, stem diameters, and top heights) of 84 (21 site−1) discrete D. bulbifera patches during late October to early December of 2012. We destructively harvested D. bulbifera biomass, sorted by tubers, stems, leaves, and bulbils; counted units of bulbils and underground tubers (dependent variables); and dried to a constant weight. Mean percentages of tuber, stem, leaf, and bulbil fractions in total biomass were 42.0, 15.6, 26.0, and 16.4, respectively. We developed a parameterized multiplicative prediction model and regression equation for each dependent variable. Slopes of relationships among independent and dependent variables varied by biomass and density (bulbil and tuber) of plant components. Multiplied values of independent variables: all three for total, tuber, stem, and leaf biomass; two (vine base diameter*patch height) for bulbil biomass; two (vine density*patch height) for bulbil density; and only one (stem density) for tuber density provided best (R2-based) prediction values. These models will provide nondestructive methods for estimating biomass components and density of vegetative propagules of naturally growing D. bulbifera. Models are critical for understanding the performance of D. bulbifera in its exotic range, estimating biomass to project control costs, and comparing biomass components and bulbil/tuber densities during pre- and postmanagement periods to gauge control efficacy.

Reduced density is an environmental friendly and cost effective solution to increase resilence to drought in vineyards in a contexte of climate change

Aims: Climate change imposes increasingly warm and dry conditions in most winegrowing regions. Mediterranean vineyards are particularly vulnerable and have registered, in most situations, declining yields over the past years. Although a majority of Mediterranean vineyards are still dry-farmed, yields can be increased by the implementation of irrigation. However, irrigation has an impact on increasingly affected water resources. An alternative solution to irrigation can be the adaptation of training systems. As can be shown by water balance modeling, low density non-irrigated vineyards are much less vulnerable to climatic drought compared to medium or high density vineyards. And while yields tend to be lower in low density vineyards, so are production costs. The aim of this study is to investigate to what extent low density vineyards can be a sustainable and cost effective adaptation for grape growing in dry climates.Methods and results: A water balance model was applied to conceptual vineyards with different soil water holding capacities and different planting densities over recent past (1981-2010) and near future (2041-2070) climatic conditions for two winegrowing scenarios (Cabernet-Sauvignon in Bordeaux and Grenache in Avignon, Côtes du Rhône). Row spacings of 2.0, 3.0 and 4.0 m were investigated for vineyards with 100, 200 and 300 mm total transpirable soil water (TTSW), while inter-vine spacing, vine architecture, and canopy height were kept similar. Projected yields were estimated to vary according to vine density and water deficit based on a meta-analysis of data published in the literature. Production costs were calculated according to an operation-based costing methodology and compared among the different scenarios on a cost per hectare basis. Gross profit per hectare, defined as grape sales revenue minus production costs, was then computed for two grape sale revenue scenarios (1 €/kg and 3 €/kg). The modeled average fraction of transpirable soil water (FTSW) varied across the different winegrowing scenarios, climate periods (recent past or near future), and TTSW and row spacing assumptions. In soils with 200 or 300 mm TTSW, the 30-day average FTSW prior to modeled grape harvest roughly doubled when 4.0 m versus 2.0 m spacing was assumed in both the recent past and near future climate scenarios. In soils with 100 mm TTSW, water deficit was more severe overall and the effect of row spacing on average FTSW was less pronounced. Changes in projected yields were estimated as a function of vine density and FTSW based on relationships published in the literature. Yields decreased with decreasing vine density and increasing water deficits, while production costs decreased with decreasing vine density. When the assumed revenue from grape sales was lower (1 €/kg), the effect of reduced production cost savings outweighed the loss in revenue caused by reduced yields, leading to increased gross profit per hectare. On the other hand, when higher grape revenue was assumed (3 €/kg), the effect of reduced yield on revenue outweighed the associated reduction in production costs, leading to reduced gross profit per hectare.Conclusions: Lower density, dry-farmed vineyards will experience less water deficit under warmer and drier climate conditions, although this difference is less pronounced in soils with less water holding capacity. When considering differences in yields, revenues, and production costs, lower density vineyards producing lower value grapes (1 €/kg) may also experience an associated increase in gross profit, while such vineyards producing higher value grapes (3 €/kg) might experience a decrease in gross profit.Significance and impact of the study: The implementation of dry-farmed, low density vineyards provides a sustainable solution for grape growing by reducing the need for irrigation water. It allows maintaining vineyards in very dry areas where water is not readily available for irrigation and where other crops (except possibly olive trees) cannot be grown. Modeling of yield, revenue, and production costs shows that this solution is also economically viable, particularly for vineyards producing lower value (€/kg) grapes. Unlike goblet trained bush vine, low density trellised vineyards are perfectly adapted for mechanization.

Forest Type Influences Population Densities of Nocturnal Lemurs in Manompana, Northeastern Madagascar

Forest loss, fragmentation, and anthropization threaten the survival of forest species all over the world. Shifting agriculture is one of these threatening processes in Madagascar. However, when its cycle is halted and the land is left to regenerate, the resulting growth of secondary forest may provide a viable habitat for folivorous and omnivorous lemur species. We aimed to identify the response of nocturnal lemurs to different successional stages of regenerating secondary, degraded mature, and mature forest across a mosaic-type landscape. We surveyed four nocturnal lemur species (Avahi laniger, Microcebus cf. simmonsi, Allocebus trichotis, and Daubentonia madagascariensis) in four forest types of varying habitat disturbance in northeastern Madagascar. We estimated densities in mature and regenerating secondary forest for the eastern woolly lemur (Avahi laniger) and mouse lemur (Microcebus cf. simmonsi), two sympatric species with folivorous and omnivorous diets respectively. We did not estimate densities of Allocebus trichotis and Daubentonia madagascariensis owing to small sample size; however, we observed both species exclusively in mature forest. We found higher population densities of A. laniger and M. cf. simmonsi in secondary than in mature forest, showing the potential of regenerating secondary forest for lemur conservation. Several environmental factors influenced the detectability of the two lemur species. While observer and habitat type influenced detection of the eastern woolly lemur, canopy height and vine density influenced detection of mouse lemurs. Understanding how different species with different diets interact with anthropogenically impacted habitat will aid future management decisions for the conservation of primate species.

Field Bindweed (Convolvulus arvensis) Control in Early and Late-Planted Processing Tomatoes

Field bindweed is a deep-rooted and drought-tolerant perennial that can be difficult to control once it has become established in specialty crops. Field studies were conducted in 2013 and 2014 to evaluate the efficacy of currently registered preplant (PP), PPI, PRE, and POST herbicides for field bindweed management in both early and late-planted processing tomatoes. Results show that bindweed cover in PPI/PRE programs (trifluralin, alone or in combination with rimsulfuron;S-metolachlor; or sulfentrazone) was reduced > 50% in early planted tomatoes, relative to the no PPI/PRE herbicide treatment (0 to 31% cover at up to 6 wk after transplanting [WAT]). Similar trends were observed with respect to field bindweed density. PP applications of glyphosate to emerged bindweed in late-planted tomatoes, coupled with PPI/PRE herbicide applications, reduced weed cover (1 to 13% at up to 6 WAT) by more than one-half when compared with plots treated with residual herbicides alone (1 to 43% at up to 6 WAT); perennial vine density was also reduced > 50%. PP herbicide burndown applications and the use of residual products can significantly improve the suppression of field bindweed in processing tomato systems. The emergence and vigor of bindweed vines may differ with respect to the timing of transplant operations and should be considered when developing management strategies

Sequential Bayesian Model Selection of Regular Vine Copulas

Regular vine copulas can describe a wider array of dependency patterns than the multivariate Gaussian copula or the multivariate Student's t copula. This paper presents two contributions related to model selection of regular vine copulas. First, our pair copula family selection procedure extends existing Bayesian family selection methods by allowing pair families to be chosen from an arbitrary set of candidate families. Second, our method represents the first Bayesian model selection approach to include the regular vine density construction in its scope of inference. The merits of our approach are established in a simulation study that benchmarks against methods suggested in current literature. A real data example about forecasting of portfolio asset returns for risk measurement and investment allocation illustrates the viability and relevance of the proposed scheme.

Do Collared Peccaries Negatively Impact Understory Insectivorous Rain Forest Birds Indirectly Via Lianas and Vines?

AbstractTropical rain forest understory insectivorous birds are declining, even in large forest reserves, yet the mechanisms remain unclear. Abundant large mammals can reshape forest structure, which degrades foraging microhabitat. We used six sites in Nicaragua, Costa Rica, and Panama with varying collared peccary (Pecari tajacu) density to test three linked hypotheses: (1) locally declining understory insectivores forage preferentially in liana tangles; (2) vine and liana density, cover, and frequency of dense tangles are lower in the presence of abundant collared peccaries; and consequently (3) abundant collared peccaries are associated with reduced understory insectivorous bird abundance. Three insectivores that declined at La Selva preferentially foraged in liana tangles: Checker‐throated Antwren (Epinecrophylla fulviventris), Dot‐winged Antwren (Microrhopias quixensis), and Ruddy‐tailed Flycatcher (Terenotriccus erythrurus). Vine density, liana cover, liana tangle frequency, and forest cover were lower in the presence of collared peccaries relative to experimental mammal exclosures, with the greatest differences at La Selva Biological Station, Costa Rica. Across sites, five of seven vine and liana measures showed negative, curvilinear relationships with peccary densities. Vine and liana measures peaked at sites with intermediate peccary density, and were low at La Selva. Structural equation models suggest negative indirect effects of the collared peccaries on focal bird densities, mediated by vine and liana density, cover, or tangle frequency. Forest area and rainfall affected both lianas and birds, but collared peccaries also contributed to the reduced abundance of understory insectivores. Indirect effects such as that suggested here may occur even in large, protected forest reserves where large mammal communities are changing.

Nitrogen Rate, Vine Density, and Weed Management Affect Colonization of Cranberry Beds following Disturbance

The interactive effects of nitrogen rate (0, 28, 56, and 112 kg/ha), vine density (0, 1.8, 3.6, and 5.4 t/ha of the cultivar ‘Stevens’), and weed management (preemergence herbicide, postemergence control, inoculation with weed seeds, and untreated) were determined on the recolonization of open spaces caused by localized biomass removal in a newly planted commercial cranberry bed. To assess the effect of the 64 treatment combinations on initial colonization, all cranberry and weed biomass was removed from a randomly selected 930-cm2area in each plot in Year 1. To quantify recolonization of the disturbed area, the same quadrat was resampled and all plant biomass was collected in Year 2. Cranberry biomass production in the disturbed area increased in a quadratic fashion with increasing N rates for all vine densities except zero. Cranberry biomass in the year after disturbance was positively correlated with cranberry biomass present in the previous year. Weed stem biomass in the year after disturbance was positively correlated with weed stem biomass from Year 1 and negatively correlated with percentage cranberry biomass from Year 1 and Year 2. Less than one-third of the treatment combinations recovered enough to produce at least 200 g/m21 yr postdisturbance (a reasonable expectation of biomass production). Growers who have low weed pressure and extensive cranberry cover on their farms can expect that disturbed areas will be recolonized by cranberry vines when they utilize adequate, but not excessive, nitrogen regimes.

Sex Pheromone of the Cranberry Root Grub Lichnanthe vulpina

The cranberry root grub Lichnanthe vulpina (Hentz) (Coleoptera: Glaphyridae) is a pest of cranberries in Massachusetts, reducing yield and vine density. (Z)-7-Hexadecenol and (Z)-7-hexadecenal were identified from the female effluvia collection by gas chromatographic-electroantennographic detection and gas chromatography-mass spectrometry. The double-bond position was confirmed by dimethyl disulfide derivatization. Both compounds were tested in the field, each alone and as blends of the two. Each compound alone captured males; however, (Z)-7-hexadecenol alone captured significantly more males than did (Z)-7-hexadecenal alone. The addition of varying amounts of (Z)-7-hexadecenal to (Z)-7-hexadecenol did not statistically affect male capture. Flight activity of the cranberry root grub may be monitored with traps baited with rubber septa containing 300 microg of (Z)-7-hexadecenol. A test of trap vane colors indicated that traps with green or black vanes maximized target male catch while minimizing nontarget catch of important cranberry pollinators.

Economic Comparison of Initial Vine Density, Nitrogen Rate, and Weed Management Strategy in Commercial Cranberry

A 2-year field trial examined the interaction of nitrogen rate, vine density, and weed management options for establishing new cranberry (Vaccinium macrocarpon) plantings. Utilizing the vigorous hybrid, `Stevens', the cost-efficiency of the treatment combinations was evaluated by combining cranberry and weed biomass data with various economic estimates. The most cost-effective production scheme for establishing new cranberry beds is to plant vines at a low density, use moderate rates of nitrogen, and apply an annual application of a preemergence herbicide. This combination produced substantial vine coverage at very low cost, reduced weed biomass by 85% compared to untreated plots, and gave the best weed control per dollar spent. Growers may opt for other reasonably successful combinations that involve higher labor costs if they can produce their own cuttings (reducing initial costs) or if they are farming with the intent to reduce overall synthetic inputs.

Identification of the female-produced sex pheromone of the scarab beetle, Hoplia equina.

Hoplia equina LeConte (Coleoptera Scarabaeidae: Melolonthinae) is a beetle pest of cranberry beds in Massachusetts. Larvae feed on the roots of the cranberry plant, reducing yield as well as vine density. The female sex pheromone was identified as 2-tetradecanone. There were eight compounds found in the airborne volatiles collected from females that elicited antennal responses from males. Of the eight compounds tested (nonanal, decanal, dodecanal, 2-dodecanone, 2-tridecanone, 2-tetradecanone, 2-pentadecanone, and 2-hexadecanone), 2-tetradecanone was the only one that attracted male beetles in the field. Combining any of the other seven antennally active compounds with 2-tetradecanone did not increase male capture.

Estimation of spatial and spectral properties of phytophthora root rot and its effects on cranberry yield

Current agricultural practices are aimed at maximizing productivity while minimizing the area of cultivated land. This is especially important in cranberry production because strict federal guidelines curtail development of new cranberry acreage on wetlands. A major component of this research is focused on the chronic effects of phytophthora root rot (PRR) because of the difficulties in detection and the significant impact on yields. PRR causes a reduction in root mass, which results in reduced canopy biomass and alters the spectral reflectance characteristics of the canopy. Detection of acute cases of PRR using color-infrared (CIR) aerial photography is straightforward from apparent bare soil on May images; however, the level of detectable chronic infection is unknown. The objectives of this study are to investigate the relationships between soil characteristics, spectral properties of the crop surface, and the severity of Phytophthora effects on cranberries. Soil, pathogen, and crop data were entered in a GIS and the relationships among the factors were studied using geostatistical methods and surface maps of the relevant GIS layers. These maps were then compared and incorporated with the data derived from remotely sensed images (CIR aerial photographs—May, 2001 and July, 2001). The spatial pattern of stressed vegetation was fairly consistent through 5 years and corresponded to spread of PRR chronic injury and low yield. The disease develops in surface depressions with low infiltration rates, which have high soil water content during July–August. The results suggest that early-season (May) CIR images have more predictive power for the yield and vine density, whereas late-season (July) images are more correlated with PRR and soil infiltration rate.

Survey of the accuracy and rapidity of several methods for vine leaf area assessment

<p style="text-align: justify;">Vine leaf area is an important viticultural parameter. Because its assessment is difficult, leaf area is not frequently taken into account. In this survey, several techniques of vine leaf area estimation are compared for their accuracy and rapidity. Leaf area is highly correlated with leaf blade fresh or dry weight. This method is destructive, because all the leaves have to be removed, and thus it can only be applied after harvest. Leaf area can also be estimated by the measurement of the lenght of two upper lateral veins. This method is precise, but very time consuming. Sample size reduction to one leaf out of four measured does not affect the quality of the estimation, though sample reduction to one leaf out of ten does. For accurate assessment, samples must be taken from multiple shoots. The third method utilizes the correlation between leaf area and shoot length. This technique combines precision and rapidity, though a standard curve should be established for each cultivar and stage of vine development. The percentage of light extinction through the vegetation can be measured by means of an L.A.I. 2000 device. Values are closely correlated to leaf area index and vine leaf area can be deduced when vine density is known. This method is very rapid (only one to two minutes per vine) but it does not distinguish between the primary and secondary leaf area. Moreover, the L.A.I. 2000 device is very expensive. Digital photographs were taken of the vines studied. Assessment of the percentage of leaf surface area, after binarisation of the image, does not lead to an accurate estimation of vine leaf area. The choice of a technique for vine leaf area estimation among the ones tested, will depend on: a) required precision, b) time availability, c) the need to dispose separately of primary and secondary leaf area, d) the possibility to invest in equipment and e) the possibility to remove leaves.</p>

Vine management for reduced-impact logging in eastern Amazonia

The presence of vines interconnecting the canopies of tropical forest trees has been thought to increase the damage to neighboring trees when a tree is felled during selective logging, resulting in larger canopy gaps and possibly prejudicting future timber harvests. To ameliorate this problem, vine cutting prior to logging has been recommended as a forest management tool. However, at present, little information exists on the economic and ecological impacts of vine cutting on tropical forest management. We undertook a study of vine management in a 210 ha forest stand. Our first objective was to determine vine species composition, stem densities, and the abilities of different vine species to resprout following cutting. Secondly, we assessed the degree of tree canopy connectedness due to vines and the amount of damage associated with felling trees with intercrown vine connections. Finally, we looked at the costs of vine cutting as a forest management tool. Vine density was found to differ among forest phases, being three times greater in young building phase forest than in mature forest. We encountered 63 species of vines in two (2 × 1400 m) transects and among the most common species, the degree of resprouting following cutting differed significantly. Typically, vines connected each tree to the crowns of from three to nine other trees. Felling trees with many vine connections resulted in canopy gaps that were twice as large as those created in the felling of vine-free trees. Although vine cutting prior to logging can reduce logging damage, it costs approximately $16 ha −1, on average. This is equivalent to 8% of the profits of a typical logging-only operation in the region. Reductions in the cost of vine cutting could come with the development of species-specific cutting prescriptions that would reduce the total number of vine stems cut by focusing cutting efforts on aggressive species likely to cause silvicultural problems.

Heterosis and combining ability ofSolanum tuberosum Group Andigena haploids

Combining ability analysis was done on a diallel cross of a random sample of four different cultivated diploid potato populations (Solanum tuberosum Group Andigena haploid, Gp. Tuberosum haploid, Gp. Phureja and Gp. Stenotomum) to determine the amount of heterosis and the gene action involved in the inheritance of tuber yield, fresh vine yield, total plant accumulation (tuber+vine) fresh and dried, dry vine yield and density (specific gravity). The analyses of variance on data from two locations demonstrated significant general combining ability for most traits, indicating a preponderance of additive gene action. Specific combining ability was not significant for any of the traits. Heritabilities for the more important traits such as tuber yield and density were large enough to ensure progress from selection.