Pure Trees Research Articles

Effect of Different Plant Communities on Fine Particle Removal in an Urban Road Greenbelt and Its Key Factors in Nanjing, China

Determining the relationships between the structure and species of plant communities and their impact on ambient particulate matter (PM) is an important topic in city road greenbelt planning and design. The correlation between the distribution of plant communities and ambient PM concentrations in a city road greenbelt has specific spatial patterns. In this study, we selected 14 plant-community-monitoring sites on seven roads in Nanjing as research targets and monitored these roads in January 2022 for various parameters such as PM with aerodynamic diameters ≤10 µm (PM10) and PM with aerodynamic diameters ≤2.5 µm (PM2.5). We used a spatial model to analyze the relationship between the concentrations of ambient PM10 and PM2.5 and the spatial heterogeneity of plant communities. The consequences revealed that the composition and species of plant communities directly affected the concentrations of ambient PM. However, upon comparing the PM concentration patterns in the green community on the urban road, we found that the ability of the plant community structures to reduce ambient PM is in the order: trees + shrubs + grasses > trees + shrubs > trees + grasses > pure trees. Regarding the reduction in ambient PM by tree species in the plant community (conifer trees > deciduous trees > evergreen broad-leaved trees) and the result of the mixed forest abatement rate, coniferous + broad-leaved trees in mixed forests have the best reduction ability. The rates of reduction in PM10 and PM2.5 were 14.29% and 22.39%, respectively. We also found that the environmental climate indices of the road community, temperature, and traffic flow were positively correlated with ambient PM, but relative humidity was negatively correlated with ambient PM. Among them, PM2.5 and PM10 were significantly related to temperature and humidity, and the more open the green space on the road, the higher the correlation degree. PM10 is also related to light and atmospheric radiation. These characteristics of plant communities and the meteorological factors on urban roads are the foundation of urban greenery ecological services, and our research showed that the adjustment of plant communities could improve greenbelt ecological services by reducing the concentration of ambient PM.

Field Trials to Assess the Growth, Survival, and Stomatal Densities of Five Mexican Pine Species and Their Hybrids under Common Plantation Conditions

Understanding hybridization is important for practical reasons, as the presence of hybrid trees in seed stands can influence the success of natural regeneration and reforestation. Hybridization creates new gene combinations, which can promote or enhance adaptation to new or changing environments. In the present research, we aimed, for the first time, to evaluate and compare the growth and survival of 541 putative hybrid seedlings and 455 seedlings of the pure parental trees of Pinus arizonica, P. durangensis, P. engelmannii, P. leiophylla, and P. teocote, in two reciprocal trials of duration 27 months in the Sierra Madre Occidental (SMO), Durango, Mexico. We also examined the possible correlation between needle stomatal density and seedling growth and survival. The overall analysis of the data showed that the mean height to the apical bud was significantly higher (p = 0.01) in the hybrids than in the pure trees. Considering both trials, the survival rate of P. arizonica (p = 0.002) and P. durangensis (p = 0.01) hybrids was significantly higher than that of the pure trees. The growth parameters were significantly correlated with the mean stomatal density (p < 0.01). Stomatal density and survival at the seed stand level were significantly and positively correlated in the hybrids, but not in the pure trees. In summary, Pinus hybrids generally exhibited the same ability as the pure species (or sometimes a greater ability) to withstand weather conditions, survive, and grow effectively in both growth trials. The systematic use of natural pine hybrids in Mexico could therefore be considered a possible option for sustainable management and as a component of adaptive silviculture.

Advantage of mixed trees in the trade-off between soil water storage and tree biomass: A meta-analysis from artificially planted forests in Chinese Loess Plateau

Afforestation is an effective measure to combat land degradation and mitigate climate change. However, afforestation tends to consume a tremendous amount of soil moisture while increasing vegetation biomass and coverage. Although convincing evidence indicates that mixed trees have higher resistance and resilience to climate change and natural disturbance than pure trees, it is unclear how tree mixtures affect the relationship between soil water storage and tree biomass. By conducting a meta-analysis of 86 observations from 27 studies, we showed that there was a trade-off between soil water storage and tree biomass in artificially planted trees on the Loess Plateau, with an average root mean square deviation (RMSD) value of 0.22. The RMSD value between soil water storage and tree biomass for mixed trees was significantly lower than that for pure trees, and the relative benefits of the trade-off were biased toward soil water storage. In dry areas (aridity index (AI) < 0.3), the RMSD value between soil water storage and tree biomass of artificially planted trees was the highest, and this value of mixed trees was significantly lower than that of pure trees. In terms of different plantation ages, the RMSD value between soil water storage and tree biomass for mixed trees was significantly lower than that for pure trees in plantations aged >20 years. Additionally, RMSD values between soil water storage and tree biomass under different afforestation patterns were negatively correlated with the initial water storage and soil organic carbon content. Our results show that tree mixtures optimize the trade-off between soil water storage and tree biomass in arid and semiarid areas.

Характеристика дубових деревостанів у природному заповіднику "Медобори"

Встановлено, що в природному заповіднику "Медобори" насадження з участю дуба звичайного (від трьох одиниць і більше) є панівним типом деревостанів і займають 43,96 % лісових площ, переважно створені штучно за типом корінних. Проаналізовано основні таксаційні показники деревостанів дуба звичайного з поквартальних підсумків Таксаційного опису природного заповідника "Медобори". Проведено віковий аналіз досліджуваних деревостанів: частка молодняків становить 9,64 %, середньовікових – 83,13 %, пристигаючих – 0,24 %. Визначено, що деревостани з участю дуба звичайного зростають у чотирьох типах лісорослинних умов: вологій грабово-буковій діброві (11,13 %), вологій грабовій діброві (13,65 %), свіжій грабово-буковій діброві (27,85 %), свіжій грабовій діброві (48,21 %). За ярусністю дубові деревостани переважно є простими. Встановлено, що дубняки характеризуються високою продуктивністю – 89,9 % ростуть за першим і вище першого бонітетом. 68,6 % насаджень – високоповнотні, а низькоповнотних є вкрай мало. Математичному аналізу підлягали компоненти: вік, діаметр, повнота, запас деревостану. За розрахунковим значенням стандартного відхилення та коефіцієнта варіації можна стверджувати, що розмах варіації показника "повнота" характеризується середнім значенням мінливості ознаки. Інші показники мають широкий діапазон розсіювання у досліджених сукупностях.

Degree of Hybridization in Seed Stands of Pinus engelmannii Carr. In the Sierra Madre Occidental, Durango, Mexico.

Hybridization is an important evolutionary force, because interspecific gene transfer can introduce more new genetic material than is directly generated by mutations. Pinus engelmannii Carr. is one of the nine most common pine species in the pine-oak forest ecoregion in the state of Durango, Mexico. This species is widely harvested for lumber and is also used in reforestation programmes. Interspecific hybrids between P.engelmannii and Pinus arizonica Engelm. have been detected by morphological analysis. The presence of hybrids in P. engelmannii seed stands may affect seed quality and reforestation success. Therefore, the goals of this research were to identify introgressive hybridization between P. engelmannii and other pine species in eight seed stands of this species in Durango, Mexico, and to examine how hybrid proportion is related to mean genetic dissimilarity between trees in these stands, using Amplified Fragment Length Polymorphism (AFLP) markers and morphological traits. Differences in the average current annual increment of putative hybrids and pure trees were also tested for statistical significance. Morphological and genetic analyses of 280 adult trees were carried out. Putative hybrids were found in all the seed stands studied. The hybrids did not differ from the pure trees in vigour or robustness. All stands with putative P. engelmannii hybrids detected by both AFLPs and morphological traits showed the highest average values of the Tanimoto distance, which indicates: i) more heterogeneous genetic material, ii) higher genetic variation and therefore iii) the higher evolutionary potential of these stands, and iv) that the morphological differentiation (hybrid/not hybrid) is strongly associated with the Tanimoto distance per stand. We conclude that natural pairwise hybrids are very common in the studied stands. Both morphological and molecular approaches are necessary to confirm the genetic identity of forest reproductive material.

Estimating the effect of Pinus massoniana Lamb plots on soil and water conservation during rainfall events using vegetation fractional coverage

Abstract Determining the effects of the critical structure of forests on soil and water conservation aids in understanding forest functions and scientific decision-making in management practices. Quadratic polynomial regression models were established for five pure tree ( Pinus massoniana Lamb) plots between vegetation fractional coverage (VFC) and soil/water conservation effects (SCE/WCE) for 144 erosive rainfall events from 2007 to 2010 in Hetian Town, Changting County, Fujian Province, a typical water-eroded area in southern China. The SCE/WCE corresponds to the ratios of soil loss/runoff depth of each tree plot to those of the control plot under each rainfall event. The results show that increasing VFC exhibits descending (DS), descending–ascending (DA), ascending–descending (AD), and ascending (AS) trends in the VFC–SCE and VFC–WCE curves, which indicate positive or negative effects of plot trees on soil and water conservation. In general, the effects on soil conservation on the plots were more notable than those on water conservation, and most of the SCE and WCE values reflect the positive effect of trees on soil and water conservation. Most determination coefficients of both the VFC–SCE and VFC–WCE models exceeded 0.6, and varied with the year and the effect. The positive effects of the pure trees occurred mainly during rainfall events with relatively higher rainfall depth, stronger intensity, and shorter duration, whereas the negative effects occurred mainly during rainfall events with lower rainfall depth, weaker intensity, and longer duration. The transition effects DA and AD appeared largely during rainfall events with moderate rainfall depth, intensity, and duration. The critical VFCs for soil and water conservation during rainfall events were 0.4 and 0.5, respectively, which provided a reference for the evaluation and planning of forest reconstruction in this and similar water-eroded areas.

Generative structural representation of tonal music

The usefulness and desirability of representation schemes which explicitly show musical structure has often been commented upon. A particular aim of music theory and analysis has been to describe and derive musical structure, and this article discusses computational systems based on this work. Six desirable properties of a structural representation are described: that it should be constructive, derivable, meaningful, decomposable, hierarchical, and generative. Previous computational work based on the generative and reductional theories of Schenker and of Lerdahl and Jackendoff is examined in the light of these properties. Proposals are made for a representational framework which promises the desirable properties. The framework shares characteristics with earlier work but does not use pure trees as a representational structure, instead allowing joining of branches in limited circumstances to make directed acyclic graphs. Important issues in developing a representation scheme within this framework are discussed, especially concerning the representation of polyphonic music, of rhythmic patterns, and of up-beats. An example is given of two alternative representations within this framework of the same segment of music used to exemplify earlier work: the opening of the theme of Mozart's piano sonata in A major, K.331.

Resource capture and tree-crop interaction in Albizia procera -based agroforestry system

A field experiment was conducted in a randomized block design at the National Research Centre for Agroforestry, Jhansi (UP) during two consecutive years (2000–01 and 2001–02). The experiment comprised eight treatments: T1– trees allowed to grow normally + crop, T2 – pruning of trees up to 70% plant height + crop, T3 – trees allowed to grow normally + soil barrier + crop, T4 – pruning of trees up to 70% plant height + soil barrier + crop, T5 – T1 + irrigation as per requirement of crop, T6 – pruning of trees up to 70% plant height + irrigation as treatment 5, T7– pure trees, and T8– pure crops (control). Blackgram (Phaseolus mungo Roxb.)/Mustard (Brassica juncia Coss.) crop sequence was included as an intercrop in the tree-crop system. Germination, plant height and branching of intercrops (blackgram and mustard) in the first row from the tree base was less compared to the second, third and fourth rows from tree base during both years. The competitive effect of trees on yield attributes and yield of blackgram and mustard was only observed in the first row of crop from tree base during the first year and this difference was wider during the second year. The light intercepted by under storey crops (blackgram and mustard) was more when the trees were pruned up to 70% plant height than when the trees were allowed to grow normally. However the value of light intercepted by crops was less in the tree-crop system than in the open field. The soil barrier was fully able to restrict the movement of root systems.

Benefits and costs of intercropping reforestation in the Atlantic lowlands of Costa Rica.

Agroforestry options as a means of promoting reforestation were testedby establishing with 10 farmers simple comparisons between pure plantations andtimber trees with annual or perennial intercrops. Two year-old intercroppedtrees on-farm had 22–48% greater height and 24–38% greater diameterthan trees in pure plantations. The exception was Cordiaalliodora that did not respond significantly to intercropping withcassava (Manihot esculenta). Only intercrops with the mostvaluable crops on agricultural soils produced a return to labour above thedailywage rate. On non-agricultural soils, farmers only intercrop a small area oftheir plantations with subsistence crops to meet home consumption needs. In thecontext of Costa Rica intercropping appeared to have a limited potential tofinance the reforestation costs of farmers.

Herbivory and tree mortality across a pinyon pine hybrid zone.

We examined the abundances of three common insect herbivores on pure and hybrid pinyon pines along a 250-km transect in west-central Arizona, United States. Using six morphological traits, we developed a hybrid index to classify trees as pure Pinus californiarum, hybrid, or pure Pinus edulis. The insects (the stem-boring moth, Dioryctria albovittella, the scale insect, Matsucoccus acalyptus, and several species of pitch moths that produce wounds on the trunk and branches) exhibited different distributional patterns across tree types. Stem-boring moths were significantly more abundant on trees at "hybrid" sites compared to trees at "pure" sites. In addition, within hybrid sites, hybrids supported significantly more moth larvae than pure trees of either species. These two patterns support the hybrid susceptibility hypothesis in which hybrid breakdown results in increased susceptibility to herbivory. In contrast to stem-borers, there were significantly more pitch moth wounds on trees at pure P. californiarum sites than at hybrid and pure P. edulis sites. Within the hybrid zone, pitch moth abundance was equal on pure P. californiarum and hybrids, and both were significantly greater than on pure P. edulis. These within-site comparisons support the dominance hypothesis where hybrid resistance differs from one tree species, but not the other. Scale insects exhibited the most restricted distribution; over the 250 km transect they were found only in the hybrid zone. This supports the hybrid susceptibility and/or the stress hypothesis (i.e., species at the edge of their range suffer greater stress and are more susceptible to herbivory). We summed the mean numbers of these three common herbivores across sites and found that hybrid sites supported 2.1 and 3.9 times more herbivores than pure P. californiarum and P. edulis sites, respectively. Furthermore, tree mortality was on average, 35 times greater within the hybrid zone compared to pure zones of each species and was associated with the cumulative abundance of herbivores (r 2=0.646). Regardless of whether this mortality is due to insect infestation, stress or a combination of both, these results suggest that hybrid zones are important arenas of natural selection.