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1.
Accurately measuring the biophysical dimensions of urban trees, such as crown diameter, stem diameter, height, and biomass, is essential for quantifying their collective benefits as an urban forest. However, the cost of directly measuring thousands or millions of individual trees through field surveys can be prohibitive. Supplementing field surveys with remotely sensed data can reduce costs if measurements derived from remotely sensed data are accurate. This study identifies and measures the errors incurred in estimating key tree dimensions from two types of remotely sensed data: high-resolution aerial imagery and LiDAR (Light Detection and Ranging). Using Sacramento, CA, as the study site, we obtained field-measured dimensions of 20 predominant species of street trees, including 30–60 randomly selected trees of each species. For each of the 802 trees crown diameter was estimated from the aerial photo and compared with the field-measured crown diameter. Three curve-fitting equations were tested using field measurements to derive diameter at breast height (DBH) (r2 = 0.883, RMSE = 10.32 cm) from the crown diameter. The accuracy of tree height extracted from the LiDAR-based surface model was compared with the field-measured height (RMSE = 1.64 m). We found that the DBH and tree height extracted from the remotely sensed data were lower than their respective field-measured values without adjustment. The magnitude of differences in these measures tended to be larger for smaller-stature trees than for larger stature species. Using DBH and tree height calculated from remotely sensed data, aboveground biomass (r2 = 0.881, RMSE = 799.2 kg) was calculated for individual tree and compared with results from field-measured DBH and height. We present guidelines for identifying potential errors in each step of data processing. These findings inform the development of procedures for monitoring tree growth with remote sensing and for calculating single tree level carbon storage using DBH from crown diameter and tree height in the urban forest.  相似文献   

2.
This case study describes a method for utilizing leaf-off airborne laser scanning (ALS) data for mapping characteristics of urban trees. ALS data were utilized to detect and update all street trees in the tree inventory of the City of Helsinki, Finland. The inventory consists of roughly 20,000 street trees with mean diameter at breast height (DBH) of 24 cm and mean height of 10.6 m. The large number of trees makes the manual updating process very laborious. The automatic mapping procedure presented in this paper detected 88.8% of all trees in the inventory. Tree height was predicted with root mean square error (RMSE) of 1.27 meters and tree DBH with RMSE of 6.9 cm. The presented method provides a practical and cost–effective tool for the mapping of urban tree characteristics. The cost–efficiency was further enhanced because the used ALS data were originally collected for other urban planning purposes.  相似文献   

3.
Once renowned as India’s “garden city”, the fast growing southern Indian city of Bangalore is rapidly losing tree cover in public spaces including on roads. This study aims to study the distribution of street trees in Bangalore, to assess differences in tree density, size and species composition across roads of different widths, and to investigate changes in planting practices over time. A spatially stratified approach was used for sampling with 152 transects of 200 m length distributed across wide roads (with a width of 24 m or greater), medium sized roads (12–24 m) and narrow roads (less than 12 m). We find the density of street trees in Bangalore to be lower than many other Asian cities. Species diversity is high, with the most dominant species accounting for less than 10% of the overall population. Narrow roads, usually in congested residential neighborhoods, have fewer trees, smaller sized tree species, and a lower species diversity compared to wide roads. Since wide roads are being felled of trees across the city for road widening, this implies that Bangalore’s street tree population is being selectively denuded of its largest trees. Older trees have a more diverse distribution with several large sized species, while young trees come from a less diverse species set, largely dominated by small statured species with narrow canopies, which have a lower capacity to absorb atmospheric pollutants, mitigate urban heat island effects, stabilize soil, prevent ground water runoff, and sequester carbon. This has serious implications for the city’s environmental and ecological health. These results highlight the need to protect large street trees on wide roads from tree felling, and to select an appropriate and diverse mix of large and small sized tree species for new planting.  相似文献   

4.
Knowledge of allometric equations can enable urban forest managers to meet desired economic, social, and ecological goals. However, there remains limited regional data on young tree growth within the urban landscape. The objective of this study is to address this research gap and examine interactions between age, bole size and crown dimensions of young urban trees in New Haven, CT, USA to identify allometric relationships and generate predictive growth equations useful for the region. This study examines the 10 most common species from a census of 1474 community planted trees (ages 4–16). Regressions were applied to relate diameter at breast height (dbh), age (years since transplanting), tree height, crown diameter and crown volume. Across all ten species each allometric relationship was statistically (p < 0.001) significant at an α-level of 0.05. Consistently, shade trees demonstrated stronger relationships than ornamental trees. Crown diameter and dbh displayed the strongest fit with eight of the ten species having an R2 > 0.70. Crown volume exhibited a good fit for each of the shade tree species (R2 > 0.85), while the coefficients of determination for the ornamentals varied (0.38 < R2 < 0.73). In the model predicting height from dbh, ornamentals displayed the lowest R2 (0.33 < R2 < 0.55) while shade trees represented a much better fit (R2 > 0.66). Allometric relationships can be used to develop spacing guidelines for commonly planted urban trees. These correlations will better equip forest managers to predict the growth of urban trees, thereby improving the management and maintenance of New England's urban forests.  相似文献   

5.
A tree diversity inventory was carried out in urban green spaces (UGSs) of Chennai metropolitan city, India. This inventory aims to study the diversity, density and richness of trees in UGSs of Chennai. A total of one hundred 10 m × 10 m (total 1 ha) plots were laid to reveal tree diversity and richness of UGSs. Trees with ≥10 cm girths at breast height (gbh) were inventoried. We recorded 45 species in 42 genera and 21 families. Caesalpiniaceae and Fabaceae each with 6 species dominated the study area followed by Arecaceae (3). Density and stand basal area of the present study were 500 stems ha?1 and 64.16 m2, respectively. Most of the inventoried trees were native (31 species) and deciduous (28 species). Fabaceae and Caesalpiniaceae dominated the present study area in terms of stand basal area and density. The Shannon diversity index and evenness of study area were 2.79 and 0.73, respectively. The most important species and families based on species important value index (IVI) and family important value index were Albizia saman, Polyalthia longifolia and Azadirachta indica; Fabaceae, Caesalpiniaceae and Annonaceae respectively. We find Chennai's urban forest is relatively superior to many urban forests of the world in terms of stand basal area and species richness. Results emphasize the importance of enhancement of urban green spaces in Chennai metropolitan city.  相似文献   

6.
The aim of this study was to test whether fragmentation or recreational use affect tree regeneration in urban forests, and to quantify these effects. We sampled tree saplings at different distances from edges in spruce (Picea abies) dominated forests, and at different distances from paths that represented different levels of wear. Generalized linear mixed models were used to test our hypotheses. We found that fragmentation favours the regeneration of deciduous trees in urban spruce dominated forests: distance from the edge had a pronounced effect on regeneration, at least up to 80 m into the forests. Saplings of Betula pendula, Populus tremula, other deciduous species and Pinus sylvestris benefited from edge conditions. Betula pubescens saplings, however, were most abundant in the interior and small Sorbus aucuparia saplings at 25–30 m from the edge. All species suffered from the direct effects of trampling, while varying responses of species to distance from the paths were observed up to 6 m, and possibly further. As trees essentially define the living conditions for other forest species, we suggest that the spatial extent of edge and trampling effects should be studied for different types of forests. This knowledge should then be used in urban forestry and planning to define the threshold value that will allow for at least some “intact” interior. We suggest a diameter larger than 160 m to support indigenous species in boreal spruce dominated forests.  相似文献   

7.
Heritage trees in a city, echoing factors conducive to outstanding performance, deserve special care and conservation. To understand their structural and health conditions in urban Hong Kong, 30 defect-disorder (DD) symptoms (physical and physiological) subsumed under four tree-position groups (soil-root, trunk, branching, and crown-foliage) and tree hazard rating were evaluated. The surveyed 352 trees included 70 species; 14 species with 233 trees were native. More trees had medium height (10–15 m), medium DBH (1–1.5 m) and large crown (>15 m). In ten habitats, public park and garden (PPG) accommodated the most trees, and roadside traffic island (RTI) and public housing estate (PH) had the least. Tree dimensions and tree habitats were significantly associated. The associations between the 2831 DD and tree-position groups, tree habitats and tree hazard rating were analyzed. Fourteen trees from Ficus microcarpa, Ficus virens and Gleditsia fera had high hazard rating, 179 trees from 22 species moderate rating, and 159 trees from 55 species low rating. RTI, roadside tree strip (RTS), roadside tree pit (RTP), roadside planter (RP) and stone wall (SW) had more moderate hazard rating, and PPG, roadside slope (RS) and government, institutional and community land (GIC) more low rating. Redundancy analysis showed that DD were positively correlated with RTS, RTP, RP and SW, but negatively correlated with PPG, RS and GIC (p < 0.05). The DD significantly increased tree hazard rating and failure potential. Future management implications for heritage-tree conservation and enhancement focusing squarely on critical tree defect-disorder in urban Hong Kong were explored, with application to other compact cities.  相似文献   

8.
In conjunction with urbanization and its importance as a major driver of land-use change, increased efforts have been placed on understanding urban forests and the provisioning of ecosystem services. However, very little research has been conducted on private property and little is known about the structure and function of privately owned urban forests. This research examines the structure of and carbon storage services provided by private residential urban forests in a moderate-sized Midwestern city. The primary research questions are as follows: What is the structure of private urban forests, and how does it vary across parcels? How much carbon is stored in tree and soil pools of private urban forests, and how does carbon vary across parcels? Ecological inventories were conducted on 100 residential parcels within 14 Neighborhood and Homeowners Associations of varying size and development age. Tree species richness, diversity, density, and diameter distribution were determined on a per parcel basis and for the entire tree population sampled. Further, tree and soil carbon storage were determined for each parcel. Results of this research demonstrated large variability in per-parcel tree metrics. Twelve of the parcels sampled had two or fewer trees, while eleven had greater than 50 trees. Further, tree carbon storage ranged from no carbon to 11.22 kg C m?2. Alternatively, soil carbon storage was less variable and averaged 4.7 kg C m?2, approximately 1.9 times higher than the average carbon stored in trees (2.5 kg C m?2). Management efforts aimed at maintaining or enhancing carbon storage and other ecosystem services should focus on both soil protection and maximizing services in living biomass. Our results demonstrate that sustaining tree-produced ecosystem services requires maintenance of large old trees and species diversity, not only in terms of relative abundance, but also relative dominance, and in combination, species–specific size distributions.  相似文献   

9.
Inter-annual canopy growth is one of the key indicators for assessing forest conditions, but the measurements require laborious field surveys. Up-to-date LiDAR remote sensing provides sufficient three-dimensional morphological information of the ground to monitor canopy heights on a broad scale. Thus, we attempted to use multi-temporal airborne LiDAR datasets in the estimation of vertical canopy growth, across various types of broad-leaved trees in a large urban park.The growth of broad-leaved canopies in the EXPO '70 urban forest in Osaka, Japan was assessed with 19 plots at the stand level and 39 selected trees at the individual-tree level. Airborne LiDAR campaigns repeatedly observed the park in the summers of 2004, 2008, and 2010. We acquired canopy height models (CHMs) for each year from the height values of the uppermost laser returns at every 0.5 m grid. The annual canopy growth was calculated by the differences in CHMs and validated with the annual changes in field-measured basal areas and tree heights.LiDAR estimations revealed that the average annual canopy growth from 2004 to 2010 was 0.26 ± 0.11 m m−2 yr−1 at the plot level and 0.26 ± 0.10 m m−2 yr−1 at the individual-tree level. This result showed that growing trends were consistent at different scales through 2004 to 2010 despite uncertainty in estimating short-term growth for small crown areas at the individual-tree level. This LiDAR-estimated canopy growth shows a moderate relation to field-measured increase of basal areas and average heights. The estimation uncertainties seem to result from the complex canopy structure and irregular crown shape of broad-leaved trees. Challenges still remain on how to incorporate the growth of understory trees, growth in the lateral direction, and gap dynamics inside the canopy, particularly in applying multi-temporal LiDAR datasets to the large-scale growth assessment.  相似文献   

10.
Blockages in sewer pipes caused by roots are very common and several tree and shrub species are reported to be particularly likely to cause root intrusion. This study examined the relative ability of roots of different species to intrude into urban sewer pipes.Data on root-intruded pipes and the woody plants surrounding these pipes were collected from two Swedish cities, Malmö and Skövde. Plant material, location data and closed-circuit television (CCTV) inspections on root-intruded pipes with a total length of 33.7 km, containing 2180 different points of root intrusion, were examined. An inventory of 4107 woody plants was compiled.The results showed that broad-leaved trees dominated as a cause of root intrusion, but that conifers and a number of shrubs, e.g. the genera Ligustrum, Spiraea and Syringa, were also likely to have caused root intrusion. Malus floribunda Van Houtte was found to have the highest mean share of root intrusions per estimated number of pipe joints when all joints and all root intrusions within a 10 m radius from trees were calculated (0.694, maximum number of intrusions per joint 1.0), while Populus canadensis ‘Robusta’ Moench had the second highest, with 0.456 intrusions per estimated joint. However, other Malus and Populus species and cultivars had a much lower mean share of root intrusions.Most species seemed capable of causing root intrusion, and not only species of the genera Populus and Salix that were previously seen as the species most likely to cause damage to stormwater and sewer systems. There were differences in the frequency of joint intrusion by roots of different species, but the reasons for these differences were not identified and further research in the area is needed.  相似文献   

11.
Decayed wood is a common issue in urban trees that deteriorates tree vitality over time, yet its effect on biomass yield therefore stored carbon has been overlooked. We mapped the occurrence and calculated the extent of decayed wood in standing Ulmus procera, Platanus × acerifolia and Corymbia maculata trees. The main stem of 43 trees was measured every metre from the ground to the top by two skilled arborists. All trees were micro-drilled in two to four axes at three points along the stem (0.3 m, 1.3 m, 2.3 m), and at the tree’s live crown. A total of 300 drilling profiles were assessed for decay. Simple linear regression analysis tested the correlation of decayed wood (cm2) against a vitality index and stem DBH. Decay was more frequent and extensive in U. procera, than P. acerifolia and least in C. maculata. Decay was found to be distributed in three different ways in the three different genera. For U. procera, decay did appear to be distributed as a column from the base to the live crown; whereas, decay was distributed as a cone-shape in P. acerifolia and was less likely to be located beyond 2.3 m. In C. maculata decay was distributed as pockets of variable shape and size. The vitality index showed a weak but not significant correlation with the proportion of decayed wood for P. acerifolia and C. maculata but not for U. procera. However, in U. procera, a strong and significant relationship was found between DBH and stem volume loss (R2 = 0.8006, P = 0.0046, n = 15). The actual volume loss ranged from 0.17 to 0.75 m3, equivalent to 5%–25% of the stem volume. The carbon loss due to decayed wood for all species ranged between 69–110 kg per tree. Based on model’s calculation, the stem volume of U. procera trees with DBH ≥ 40 cm needs to be discounted by a factor of 13% due to decayed wood regardless of the vitality index. Decayed wood reduces significantly the tree’s standing volume and needs to be considered to better assess the carbon storage potential of urban forests.  相似文献   

12.
Urban woodlands provide aesthetic experiences and recreational opportunities for people. The characteristics of vegetation are closely linked to these benefits. However, previous research has primarily focused on the effects of trees on aesthetic preference, while less research has involved the understory. This paper explored the relationship between understory characteristics and aesthetic or recreational preference. Twenty one images were rated for preference by participants (n = 184) on a five-point scale. Except for the original picture, these images were created using the photomontage method that manipulated understory height, the flowers and the path of the original picture. Results indicated that: (1) concerning aesthetic preference, all vegetated images were preferred more than the paved image, but for recreational preference, the paved image was preferred over the vegetated images; (2) the height of understory vegetation had a significant influence on aesthetic and recreational preference; (3) flowers and path increased aesthetic and recreational preference significantly. These results suggest that, in management of woodland, (1) maintaining the understory vegetation in middle height (0.5–1.0 m) or in full-mixed heights (low + middle + tall) (2) increasing shade-tolerance flowers and constructing a winding path in woodland would be preferred by the public.  相似文献   

13.
Greening of shopping centre parking lots is a potentially important strategy that can contribute to urban carbon mitigation efforts, improve aesthetics and the shopping experience of consumers, whilst adding to urban biodiversity. Twenty-eight shopping centre parking lots in six Eastern Cape urban centres, South Africa, were sampled to determine tree species composition, density and annual carbon sequestration potential. The best case parking lot found during the study was used as a benchmark to display the difference between current tree density and above-ground carbon stocks relative to the potential optimum. The highest tree density was 66 trees ha?1, whereas the average density across all sampled parking lots was less than half that (27.2 ± 22.6 trees ha?1). The average annual carbon sequestration potential per parking lot was 1390 ± 2503 kg ha?1. Planting density was positively related to annual sequestration rates, whilst parking lot age and the mean annual rainfall of the town had no influence. Mean tree species richness per parking lot was 2.3 ± 1.8 species, with a positive relationship to parking lot size, but not to mean annual rainfall of the site. The majority of trees (62.5%) in parking lots were alien species, although newer parking lots had significantly greater proportions of indigenous species. There was no difference in mean annual carbon sequestration rate per tree between indigenous and alien trees species. Low tree densities and small parking lot areas constrained the potential for earning carbon credits from trees in parking lots. Nonetheless, planners and designers need to be more aware of the potential contribution of trees towards urban sustainability.  相似文献   

14.
In ecological planning, cost-effective but accurate methods for the assessment of habitats and species are needed. In this study we investigated whether the multi-scale Modified Whittaker plot (MWP) method is suited for vascular plant surveys as a basis for habitat assessment. We measured total and endangered species richness in ten urban forests in Hannover, Germany. The MWPś time efficiency and effectiveness in capturing species richness were quantified and compared to complete field surveys. The MWP method estimated both greater and lower species numbers per habitat, the absolute deviation ranged from +60 to −15 species. It generally captured fewer endangered plant species than the complete field survey. In particular, the method did not detect species with a high category of endangerment. Regarding time efficiency, the MWP method took an average of 186 minutes per habitat, while the complete field surveys were more time consuming (mean = 265 minutes). In small habitats (<1.0 ha) the full survey took less time than the MWP method. To determine the applicability for nature conservation and ecological planning, we evaluated the species data derived from the two methods by using common habitat evaluation criteria. In most cases, the species data received from the MWP method resulted in lower habitat values compared to the use of data from the full surveys. We conclude that comprehensive habitat evaluation exceeds the applicability of the MWP method which may miss locally rare species. However, the MWP method provides an opportunity to efficiently estimate plant species richness patterns in urban forests and, thus, holds the potential to convey basic information for an overall monitoring of species diversity and may lead to specific habitat assessment efforts.  相似文献   

15.
The implementation of trees in urban environments can mitigate outdoor thermal stress. Growing global urban population and the risk of heatwaves, compounded by development driven urban warmth (the urban heat island), means more people are at risk of heat stress in our cities. Effective planning of urban environments must minimise heat-health risks through a variety of active and passive design measures at an affordable cost. Using the Solar and Longwave Environmental Irradiance Geometry (SOLWEIG) model and working within the bounds of current urban design, this study aimed to quantify changes in mean radiant temperature (Tmrt) from increased tree cover at five different 200 × 200 m urban forms (including compact mid-rise development, residential and open grassy areas) within a suburb of Adelaide, Australia during summer. Following a successful validation of SOLWEIG, street trees were strategically distributed throughout each of the five urban forms and the model run over five warm sunny days (13–17 February 2011). Results showed spatially averaged daytime (7:30–20:00) Tmrt reduced by between 1.7 °C and 5.1 °C at each site, while under peak heating conditions (16 February, 14:00) Tmrt reduced by between 2.0 °C and 7.1 °C. The largest reduction in Tmrt under peak warming conditions was at the residential site, despite having the fewest number of trees added. Directly below clusters of trees, Tmrt could be reduced by between 14.1 °C and 18.7 °C. SOLWEIG also highlighted that more built-up sites showed higher Tmrt under peak warming conditions due to increased radiation loading from 3D urban surfaces, but over the course of the day, open sites were exposed to greater and more uniform Tmrt. This study clearly demonstrates the capacity of street trees to mitigate outdoor thermal stress and provides guidance for urban planners on strategic street tree implementation.  相似文献   

16.
Roads destroy natural habitats. To reduce erosion, support wildlife and decorate surroundings, ornamental trees are planted near the roadside. However, it is inadequately understood how roads influence fruit production of trees and birds that consume their fruits, within urban landscapes. During the autumn and winter of 2012–2013, we studied the extent to which birds used the fruit from rowanberry trees (Sorbus aucuparia), in two cities along a 700 km latitudinal gradient in Finland. In matched pair design (total of 35 pairs), we compared roadside trees (approximately 8 m from main roads) with trees grown away from roads (control trees; approximately >80 m from the roads). During the autumn, each rowanberry tree pair was photographed, and frugivorous birds were surveyed twice per month until all of the rowanberry fruit-crop was consumed. There was no difference in fruit crop size between roadside trees and control trees. A total of eight frugivorous bird species and 960 individuals were observed foraging in roadside trees. The three most abundant species were Bohemian waxwing (Bombycilla garrulus, 56.4%), Pine Grosbeak (Pinicola enucleator, 28.9%) and Fieldfare (Turdus pilaris, 10.5%). Total abundance and species richness of frugivorous birds were lower around roadside trees than control trees during most of the study period. Fruits were consumed later from roadside trees than from control trees, probably due to human-caused disturbance. Therefore, roadside rowanberry trees extended the period when frugivorous birds stayed in urban habitats. Later consumption of fruits in northern areas than in southern areas was related to earlier peak abundance of frugivorous birds in south than in north. Our results indicated that rowanberry is a suitable ornamental tree for urban and roadside landscaping and may additionally benefit birds and other frugivorous wildlife.  相似文献   

17.
We studied the spatial distribution of saplings in the vicinity of other saplings and mature trees in heavily worn urban forests. Our aim was to identify favorable microsites for saplings to regenerate under different levels of wear. We hypothesized that these safe microsites were situated close to tree trunks that might offer shelter from trampling caused by humans and their pet dogs. The distribution of saplings was explored at 0.1–0.6 m to the nearest sapling and 0.1–2 m to the nearest mature tree. Sorbus aucuparia was the most abundant sapling species, followed by Populus tremula, Betula pubescens and Picea abies. These species all tended to cluster with their conspecific saplings and were generally randomly distributed with respect to mature trees. Saplings of S. aucuparia and P. tremula favored growing close to mature P. abies (already at 0.4–0.8 up to 2 m from the trunk base, respectively) and S. aucuparia trees (at 0.2–0.4 m up to 2 m). Betula sp. and Acer platanoides grew close to Pinus sylvestris trees. Furthermore, with increased levels of wear, saplings clustered more likely together and close to tree trunks. The results are contrary to the gap regeneration hypothesis known from rural unworn forests where saplings often grow in canopy gaps. We suggest the idea of a ‘sheltering group’, i.e. tree groups and thickets of densely growing conspecific saplings, for the maintenance of regeneration of saplings and other vegetation in heavily worn recreational forests. Since urban forestry may strongly affect the existence and spatial location of a high variety of microhabitats, small-scale spatial exploration is needed to identify microsites that offer opportunities for natural regeneration under heavy recreational use. To maintain natural regeneration and the survival of saplings in worn urban forests, we recommend microhabitat-level species-specific forest management.  相似文献   

18.
Citizen science has been gaining popularity in ecological research and resource management in general and in urban forestry specifically. As municipalities and nonprofits engage volunteers in tree data collection, it is critical to understand data quality. We investigated observation error by comparing street tree data collected by experts to data collected by less experienced field crews in Lombard, IL; Grand Rapids, MI; Philadelphia, PA; and Malmö, Sweden. Participants occasionally missed trees (1.2%) or counted extra trees (1.0%). Participants were approximately 90% consistent with experts for site type, land use, dieback, and genus identification. Within correct genera, participants recorded species consistent with experts for 84.8% of trees. Mortality status was highly consistent (99.8% of live trees correctly reported as such), however, there were few standing dead trees overall to evaluate this issue. Crown transparency and wood condition had the poorest performance and participants expressed concerns with these variables; we conclude that these variables should be dropped from future citizen science projects. In measuring diameter at breast height (DBH), participants had challenges with multi-stemmed trees. For single-stem trees, DBH measured by participants matched expert values exactly for 20.2% of trees, within 0.254 cm for 54.4%, and within 2.54 cm for 93.3%. Participants’ DBH values were slightly larger than expert DBH on average (+0.33 cm), indicating systematic bias. Volunteer data collection may be a viable option for some urban forest management and research needs, particularly if genus-level identification and DBH at coarse precision are acceptable. To promote greater consistency among field crews, we suggest techniques to encourage consistent population counts, using simpler methods for multi-stemmed trees, providing more resources for species identification, and more photo examples for other variables. Citizen science urban forest inventory and monitoring projects should use data validation and quality assurance procedures to enhance and document data quality.  相似文献   

19.
《Scientia Horticulturae》2005,104(2):189-198
The advantages of the high density and protected cultivation over open field were investigated in three loquat cultivars. Both of these methods are new and have not been previously studied in Turkey. The study was conducted with Gold Nugget, Hafif Çukurgöbek, and Sayda cultivars planted at high-density with planting spaces of 3 m × 3 m in May 1997. The experiments for cultivation were done in greenhouses where the side height was 2.5 m and the highest point was 4.0 m. Phenological variables such as first blossoming, full bloom, end of bloom and harvest time and pomological variables such as fruit and seed weight, fruit dimension, seed number/fruit, and acidity were determined. The trunk diameter, 10 cm above the bud union, was also recorded each year during the study. The total above ground tree canopy volume was calculated from height and width measurements. The productivity parameters including yield/plant, yield/hectare, cumulative production/plant, cumulative production/hectare and yield/unit trunk cross-sectional area and yield/unit of canopy volume were calculated. The results indicated that protected cultivation caused earliness of 13–20 days when compared to open field. The mean yield was higher in protected cultivation than the open field for both yield/tree and yield/ha. Conversely, the mean yield was higher in open field than protected cultivation for yield/unit trunk cross-sectional area and yield/unit of canopy volume of trees. Pomological quality of the fruits was higher in the open field than protected cultivation.  相似文献   

20.
Few studies have investigated whether manipulating objective measures related to fascination and extent affect respondents’ ratings of restorative potential (RP) and estimations of fascination and extent. The following study addresses this need. We manipulated or measured variables in 27 color digital landscape model views. Tree height represented a measure of fascination. Three measures related to extent: The number of organized plant groups represented coherence. Shannon’s Information Entropy bit values represented plant species complexity. The visible view polygon area in each model represented scope. We included 65 respondents’ RP ratings for the digital model views in analyses, along with estimations of fascination (n = 48), extent (n = 43), coherence (n = 38), complexity (n = 44), and scope (n = 35). Collinearity diagnostics indicated dependency between respondents’ estimations of fascination, extent, and complexity, and between estimations of coherence and scope. A strong, inverse correlation occurred between respondents’ RP ratings and the view polygon area. Repeated measures ANOVA test results suggest that respondents’ RP ratings increased as mean designed tree height increased. RP ratings for model views depicting scattered and formally arranged plants were significantly higher than views of clustered plants. Moreover, the decrease in RP ratings between scattered and clustered scenes was greater when plants represented three bits of entropy instead of two. Chief among the implications stemming from this study is that increasingly taller trees and groundcover plants may have increasingly greater restorative potential.  相似文献   

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