Relative Height Growth Rate Research Articles

Survival and growth of northern white-cedar and balsam fir seedlings in riparian management zones in northern Minnesota, USA

Northern white-cedar (Thuja occidentalis) and balsam fir (Abies balsamea.) are co-occurring species in riparian forests of the western Great Lakes region. Throughout much of the region, northern white-cedar has been experiencing population declines due to herbivory by white-tailed deer (Odocoileus virginianus). Preferential browse on northern white-cedar removes seedlings and saplings, allowing balsam fir, as less-preferred browse species, to recruit into larger size classes and potentially out-compete northern white-cedar. There is great interest in restoring and sustaining northern white-cedar in riparian forests, but the factors that contribute to success or failure of established seedlings are not well understood. We used a riparian harvesting experiment in northern Minnesota, USA to study factors that encourage or deter survival and growth of planted northern white-cedar seedlings in riparian areas, relative to the response of balsam fir. The factors we manipulated experimentally included amount of overstory basal area (uncut or partially harvested), establishment microsite (mound, pit, slash), and browse (protected or not).Browse frequency was significantly higher on northern white-cedar than on balsam fir, particularly in the partially-harvested forest. Northern white cedar survival was similar to balsam fir when unprotected from browsing, but was higher when browsing was excluded. When protected, northern white-cedar survival approached 100% in both uncut and partially-cut forest on mound and slash microsites, whereas survival of balsam fir was significantly lower in uncut compared to partially-cut forest. Both species had low survival in pit microsites. Relative height growth rates were similar between the two species when protected from browsing, and both species had higher growth with partial-harvest. When unprotected from browsing, relative height growth of northern white-cedar was often negative, while height growth of balsam fir was only minimally reduced compared to the protected seedlings. The two species had similar relative diameter growth in the unprotected treatment, and growth of both species was reduced compared to growth when protected. When protected, northern white-cedar had a relative diameter growth advantage over balsam fir, particularly in the partial-harvest treatment. Our results suggest that a strategy to establish northern white-cedar in riparian forests may be to plant seedlings in uncut forest on raised microsites and protect these seedlings from browsing. After these seedlings are well-established, and perhaps balsam fir is intentionally eliminated, a partial-harvest may be used to release the northern white-cedar seedlings, while still maintaining pre-harvest browse protection.

상수리나무 임분 내에서 벌채 유형에 따른 조림목의 생장 특성

Abstract The objective of this study was to evaluate the effect of cutting types on microclimate and growth characteristics of afforested tree in Quercus acutissima stand after different types of cutting. The difference in temperature reaching 5.2℃ was shown in between clear cutting and selective cutting treatments. On July and August days with temperatures more than 35℃often appeared in clear cutting stand. The values of VPD in July and August were higher than those in other months. Maximum VPD of 3.99 kPa was shown in clear cutting stand on May 23 as a prolonged rainless days appeared. However, VPD in selective cutting stand always stayed under 3.0 kPa throughout growing season. A higher intensity was shown in clear cutting and strip clear cutting stands, reaching to more than 1,600 μmol m -2 s -1 at midday on early August, while that in selective cutting stand stayed about 1,500. In relative growth rate selective cutting stand showed a significantly higher relative growth rate in plant height than those in other cutting stands (p<0.05). The number of leaf in current-year branches significantly increased in selective cutting stand, whereas no increase was shown in clear cutting and strip clear cutting stands (p<0.05). In addition, relative elongation rate of current year branch also showed higher values in selective cutting stand compared with that in strip clear cutting stand (p<0.05). However, leaf mass per unit area (LMA) was higher in order of strip clear cutting, clear cutting, and selective cutting stands. From these results it is concluded that environmental conditions in clear cutting and strip clear cutting stands during growing season are more stressful to afforested tree species, resulting in lower relative growth in plant height, elongation of current-year branches, and leaf number per branch compared with those in selective cutting stand. Consequently, more data must be accumulated in the field to find out best cutting type in plantation considering the adaptational characteristic of each tree species varies with species and life span of tree is long.

Ecophysiological responses of two dominant subalpine tree species Betula albo-sinensis and Abies faxoniana to intra- and interspecific competition under elevated temperature

Seedlings of tree species Abies faxoniana and Betula albo-sinensis were grown under different competition regimes (single plant, monoculture or mixture) at ambient temperature (AT) and elevated temperature (ET) to evaluate the impact of inter- and intraspecific competition on photosynthesis capacity, N resorption efficiency, N uptake patterns, water use efficiency (foliar carbon isotope composition, δ13C) and root carbon reserve accumulation. Our results showed that ET did not have significant effects on relative height growth rate (RGRH), relative diameter growth rate (RGRD), chlorophyll fluorescence parameters (Fv/Fm, ΦPSII), light-saturated photosynthetic rate (A1400) and nitrogen uptake in A. faxoniana, but it significantly reduced the values of these parameters in B. albo-sinensis. On the other hand, RGRH of A. faxoniana was not influenced by intraspecific competition irrespective of temperature regimes, while in B. albo-sinensis intraspecific competition was severer under AT than under ET. Decreased photosynthetic capacity and reduced plant size detected in B. albo-sinensis under ET likely contribute to its low intraspecific competitive ability. However, we found positive effects of interspecific competition on A. faxoniana but negative effects on B. albo-sinensis under ET, as A. faxoniana exposed to interspecific competition showed higher RGRH, RGRD, A1400, chlorophyll fluorescence parameters, foliar δ13C, foliar N, and percentages of 15N-ammonium and 15N-nitrate recovery than did A. faxoniana exposed to intraspecific competition or no competition. The results indicate that A. faxoniana is a better competitor than B. albo-sinensis under ET. Further, A. faxoniana altered resource use patterns and had a high plasticity in its ammonium uptake in mixtures compared with monocultures under ET, while B. albo-sinensis did not change its N use pattern. In all, our results showed that high temperature stress tolerance (e.g., higher root carbon accumulation), high ability to keep carbon balance (e.g., higher water use efficiency, lower leaf respiration rate, higher Fv/Fm), as well as a better N acquisition ability make A. faxoniana a better competitor when compared to B. albo-sinensisg under ET.

Ontogenetic shifts in plant–plant interactions in a rare cycad within angiosperm communities

Gymnosperms and angiosperms can co-occur within the same habitats but key plant traits are thought to give angiosperms an evolutionary competitive advantage in many ecological settings. We studied ontogenetic changes in competitive and facilitative interactions between a rare gymnosperm (Dioon sonorense, our target species) and different plant and abiotic neighbours (conspecific-cycads, heterospecific-angiosperms, or abiotic-rocks) from 2007 to 2010 in an arid environment of northwestern Mexico. We monitored survival and growth of seedlings, juveniles, and adults of the cycad Dioon sonorense to evaluate how cycad survival and relative height growth rate (RHGR) responded to intra- and interspecific competition, canopy openness, and nearest neighbour. We tested spatial associations among D. sonorense life stages and angiosperm species and measured ontogenetic shifts in cycad shade tolerance. Canopy openness decreased cycad survival while intraspecific competition decreased survival and RHGR during early ontogeny. Seedling survival was higher in association with rocks and heterospecific neighbours where intraspecific competition was lower. Shade tolerance decreased with cycad ontogeny reflecting the spatial association of advanced stages with more open canopies. Interspecific facilitation during early ontogeny of our target species may promote its persistence in spite of increasing interspecific competition in later stages. We provide empirical support to the long-standing assumption that marginal rocky habitats serve as refugia from angiosperm competition for slow-growing gymnosperms such as cycads. The lack of knowledge of plant-plant interactions in rare or endangered species may hinder developing efficient conservation strategies (e.g. managing for sustained canopy cover), especially under the ongoing land use and climatic changes.

Relative Growth Rate of Six Soybean Genotypes Under Iron Toxicity Condition

The objective of the research was to study relative growth rate of six soybean genotypes under iron toxicity condition. The design was factorial design, with two factors; arranged in completely randomized design with three replications. The first factor was Fe concentration, consisted of two levels, i.e. (1) 0 ppm Fe and (2) 375 ppm Fe where after 7 days the acidity was not maintain at pH 3.5. The second factor was genotype, consisted of 6 genotypes, i.e. two tolerant genotypes (MLGG 0799 and MLGG 0492), three susceptible genotypes (MLGG 0915, MLGG 0768 and MLGG 0169) and one check swampland tolerant-variety (Lawit). The results showed that genotypes of MLGG 0799 and MLGG 0768 had higher rhizosphere pH levels than other genotypes. MLGG 0492 had potency to self recovery better than other genotypes based on relative growth rate (RGR) of root dry weight, plant height and plant dry weight. MLGG 0492 may have different mechanism than others because this genotype remained to have higher RGR, although it was unable to increase the rhizosphere pH. Under control and Fe treatment conditions, Lawit had no significant difference of RGR of plant dry weight to other susceptible genotypes.

Survival and growth of seven tree species from three stocktypes planted in created wetlands in Loudoun County, Virginia

Successful establishment and growth of trees in created wetlands is an important factor in efforts to compensate for forested wetland losses. Proper selection of seedlings to be planted in a replacement wetland, including tree species and stocktype, is essential to the ecological and economic viability of a wetland afforestation project. In this study seven commonly-planted forested wetland tree species and three stocktypes were planted in three created wetlands in the Piedmont region of Virginia. Quercus bicolor in 1-gallon container stocktype had the highest survival rate (96.2±2.13% SE) and Quercus phellos planted as tubeling stocktype had the lowest survival rate (18.8±3.33% SE). High survival rate occurred in 1-gallon stocktypes overall and may be related to larger initial seedling height and root collar diameter. Both tree species and stocktype explained a significant amount of variation in relative growth rates (RGR) of height (H), root collar diameter (RCD), and canopy diameter (CD), with the exception of RCDRGR for stocktype. Salix nigra and Betula nigra were good performers overall, and exhibited moderate survival and growth rates across stocktypes. These survival and growth results should be considered when tree species and stocktypes are selected for seasonally flooded or saturated sites.

Growth of mycorrhizal jack pine (Pinus banksiana) and white spruce (Picea glauca) seedlings planted in oil sands reclaimed areas

The effectiveness of ectomycorrhizal inoculation at the tree nursery seedling production stage on growth and survival was examined in jack pine (Pinus banksiana) and white spruce (Picea glauca) planted in oil sands reclamation sites. The seedlings were inoculated with Hebeloma crustuliniforme strain # UAMH 5247, Suillus tomentosus strain # UAMH 6252, and Laccaria bicolor strain # UAMH 8232, as individual pure cultures and in combinations. These treatments were demonstrated to improve salinity resistance and water uptake in conifer seedlings. The field responses of seedlings to ectomycorrhizal inoculation varied between plant species, inoculation treatments, and measured parameters. Seedling inoculation resulted in higher ectomycorrhizal colonization rates compared with non-inoculated control, which had also a relatively small proportion of roots colonized by the nursery contaminant fungi identified as Amphinema byssoides and Thelephora americana. Seedling inoculation had overall a greater effect on relative height growth rates, dry biomass, and stem volumes in jack pine compared with white spruce. However, when examined after two growing seasons, inoculated white spruce seedlings showed up to 75% higher survival rates than non-inoculated controls. The persistence of inoculated fungi in roots of planted seedlings was examined at the end of the second growing season. Although the inoculation with H. crustuliniforme triggered growth responses, the fungus was not found in the roots of seedlings at the end of the second growing season suggesting a possibility that the observed growth-promoting effect of H. crustuliniforme may be transient. The results suggest that the inoculation of conifer seedlings with ectomycorrhizal fungi could potentially be carried out on a large scale in tree nurseries to benefit postplanting performance in oil sands reclamation sites. However, these practices should take into consideration the differences in responses between the different plant species and fungal strains.

Effects of age and stand density of mother trees on early Pinus thunbergii seedling establishment in the coastal zone, China.

Effects of age and stand density of mother tree on seed germination, seedling biomass allocation, and seedling growth of Pinus thunbergii were studied. The results showed that age of mother tree did not have significant influences on seed germination, but it was significant on seedling biomass allocation and growth. Seedlings from the minimum and maximum age of mother tree had higher leaf mass ratio and lower root mass ratio than from the middle age of mother tree. Moreover, they also had higher relative height growth rate and slenderness, which were related to their biomass allocation. Stand density of mother tree mainly demonstrated significant effects on seed germination and seedling growth. Seed from higher stand density of mother tree did not decrease germination rate, but had higher mean germination time, indicating that it delayed germination process. Seedlings of higher stand density of mother tree showed higher relative height growth rate and slenderness. These traits of offspring from higher stand density of mother tree were similar to its mother, indicating significant environmental maternal effects. So, mother tree identity of maternal age and environments had important effects on natural regeneration of the coastal P. thunbergii forest.

EFFECT OF SOME BIO AND CHEMICAL FERTILIZERS ON GROWTH AND CHEMICAL COMPOSITION OF Pinus halepensis, MIL L. SEEDLINGS

In determining the most appropriate fertilizers and optimum doses of fertilizer to obtain high quality and vigorous seedlings of Pinus halepensis, this investigation was consummated throughout the two successive seasons (2011 and 2012) at the nursery of Timber Trees and Forestry Res. Dept., Hort. Res. Inst., Giza, Egypt. In derail, bio fertilizer Biogein or Rhizobacterien at 2.50 and 5.00 g/ bag as well as chemical fertilizer with Vive Rose as a foliar spray at 1.00 &2.00 g/l and NPK fertilizer (1:1:1) at the levels 1.00, 2.00 and 4.00 g/bag, were used to study such treatments on growth and chemical composition of Pinus halepensis {one year old seedling transplants grown in 14 cm diameter black polyethylene bag filled with a mixture of sand, loam 1:1,v./v.}. The results indicated that untreated seedling significant increments seedling quality (SQ) in both seasons. As well as addition Biogien at the level 2.50g/bag significantly increased plant height, stem diameter, number of the branches/plant, root length, fresh and dry weights of aerial parts (stems and leaves), roots fresh and dry weights, survival %, relative growth rate of height (RGRH), (RGRD), total dry biomass increment % and nutrient uptake in both seasons compared to controls or other treatments were used. Meanwhile, Rhizobacterien at 2.50g/bag significantly increased root length, and leaf content of chlorophyll b, carotenoids, N, and K percentage. Rhizobacterien at 5.00g/bag significantly raised seedling quality index in both seasons. From the obtained results, it could be recommended, that the addition of Biogien at 2.5 g/bags to Pinus halepensis seedlings (grown in 14 cm diameter bags thrice with one month interval from March to May during the period spent) resulted in the best and strongest seedlings, besides shortening the time in the nursery in order to reduce the cost of seedlings production and benefit our environment.

Thinning effect on height and radial growth of Pinus thunbergii Parlat. trees with special reference to trunk slenderness in a matured coastal forest in Hokkaido, Japan

To evaluate the effect of thinning on a mature coastal Pinus thunbergii Parlat. forest in Hokkaido, northern Japan, we established four study plots with different thinning intensities (control and 20, 40, and 60 % thinned at individual base; each 20 m × 20 m) and monitored them for 10 years. Radial growth of individual trees in the 60 % thinned plot was significantly greater than that in the other plots, whereas height growth in the 60 % thinned plot was significantly lower than in the other plots. Applying the height growth contribution index, which represents the trade-off between relative height growth rate and relative diameter growth rate, revealed that individual trees in the control and weakly (20 and 40 %) thinned plots had invested more in height growth compared to trees in the 60 % thinned plot. Though higher trunk slenderness value (>80) indicates higher susceptibility to meteorological disturbance such as wind storm and heavy snow, trunk slenderness in the control and the weakly thinned plots increased significantly compared to that in the 60 % thinned plot. In this study, 44.3 % of trees in the control plot had trunk slenderness values >80 over a period of 10 years. The number of trees with trunk slenderness values >80 also increased in the weakly thinned plots. In contrast, no increase was observed in the 60 % thinned plot. In Japan, the thinning intensity is legally supposed to be <35 % of stand volume, which is not enough to improve tree architecture in terms of trunk slenderness.

Effects of Soil Salinity on Growth, Ion Relations, and Compatible Solute Accumulation of Two Sumac Species: Rhus glabra and Rhus trilobata

The effects of soil salinity on growth, photosynthetic pigments, ion relations, and compatible solute accumulation of two sumac seedlings (Rhus glabra and Rhus trilobata) treated with five salinity levels in a completely randomized block design with four replications were studied. Both species were inhibited by soil salinity, but salt-damaged symptoms appeared much earlier and more severely in R. glabra, and relative height growth rates (RGRH) and photosynthetic pigment contents were much higher on average in R. trilobata. The biomass increment, root/shoot ratio, and relative shoot dry weight (DW) were significantly affected only in R. glabra. Rhus trilobata showed stable potassium (K+) concentration and low sodium (Na+) accumulation in roots, stems, and leaves, and a proline concentration 10 times greater than that of R. glabra. Overall, our findings suggest that R. trilobata is more salt-tolerant than R. glabra, which is presumably rooted in its better performance in ionic homeostasis and osmotic regulation.

Pinhão-manso: crescimento sob condições diferenciadas de irrigação e de adubação no semiárido nordestino

Uma das alternativas para ocupação do espaço deixado pelo algodão no semiárido cearense é o cultivo do pinhão-manso (Jatropha curcas L.) visando à produção do biodiesel. Face ao exposto, realizou-se este trabalho de campo para avaliar os efeitos de diferentes lâminas aplicadas (735,53; 963,30; 1.191,03; 1.418,82 e 1.646,60 mm) e níveis de adubação nitrogenada (0; 25; 50 e 75 kg ha-1 de N) no crescimento da cultura do pinhão-manso. Os dados referentes ao crescimento da fitomassa fresca epígea foram obtidos em sete diferentes épocas do ciclo da cultura (30; 60; 90; 120; 150; 180 e 210 dias após poda). De acordo com os resultados, a altura caulinar e a taxa de crescimento relativo em altura caulinar obtiveram comportamento linear e crescente com o incremento das lâminas aplicadas. A época de coleta influenciou não apenas os valores de altura, mas também de diâmetro caulinar obtendo-se, em ambas as variáveis, comportamento linear ao decorrer da condução do experimento. Houve um declínio nos valores da taxa de crescimento relativo em altura e no diâmetro caulinar causado pelos fatores climáticos (temperatura, umidade relativa, pluviosidade e evaporação) e pelo início da floração e formação de frutos.

Crescimento e fenologia de espécies de Jatropha durante a estação chuvosa

Jatropha curcas L., Jatropha mollissima (Pohl) Baill e Jatropha gossypiifolia L. são Euforbiáceas com potencial para produção de biodiesel e uso na indústria farmacêutica e em cosméticos. Objetivou-se, com este trabalho, avaliá-las em termos de crescimento e fenologia em pesquisa de campo. Adotou-se o delineamento experimental em blocos casualisados contendo na parcela 18 plantas e tendo área útil de 15 m². Nos estudos fenológicos das plantas foram consideradas as seguintes fases: estabelecimento/crescimento vegetativo, floração, frutificação e maturação/colheita. As fases fenológicas das espécies diferiram cronologicamente. Jatropha mollissima cresceu mais do que as outras espécies em altura de plantas enquanto Jatropha curcas cresceu mais em diâmetro caulinar. As maiores taxas de crescimento relativo em altura de plantas ocorreram durante o crescimento vegetativo com os maiores valores sendo registrados em Jatropha mollissima enquanto as maiores taxas de crescimento relativo, também no crescimento vegetativo, foram registradas em Jatropha curcas. As menores taxas de crescimento relativo em altura de plantas e diâmetro caulinar das espécies estudadas coincidiram com as fases reprodutivas.

Performance of established native seedlings in relation to invasive Lantana camara, rainfall and species’ habitat preferences in a seasonally dry tropical forest

Native species' response to the presence of invasive species is context specific. This response cannot be studied in isolation from the prevailing environmental stresses in invaded habitats such as seasonal drought. We investigated the combined effects of an invasive shrub Lantana camara L. (lantana), seasonal rainfall and species' microsite preferences on the growth and survival of 1,105 naturally established seedlings of native trees and shrubs in a seasonally dry tropical forest. Individuals were followed from April 2008 to February 2010, and growth and survival measured in relation to lantana density, seasonality of rainfall and species characteristics in a 50-ha permanent forest plot located in Mudumalai, southern India. We used a mixed effects modelling approach to examine seedling growth and generalized linear models to examine seedling survival. The overall relative height growth rate of established seedlings was found to be very low irrespective of the presence or absence of dense lantana. 22-month growth rate of dry forest species was lower under dense lantana while moist forest species were not affected by the presence of lantana thickets. 4-month growth rates of all species increased with increasing inter-census rainfall. Community results may be influenced by responses of the most abundant species, Catunaregam spinosa, whose growth rates were always lower under dense lantana. Overall seedling survival was high, increased with increasing rainfall and was higher for species with dry forest preference than for species with moist forest preference. The high survival rates of naturally established seedlings combined with their basal sprouting ability in this forest could enable the persistence of woody species in the face of invasive species.

Comportamento morfofisiológico da mamoneira BRS Energia submetida à irrigação com água salina

Um experimento foi conduzido na estação experimental de Irrigação e Drenagem do Instituto Federal Baiano, para avaliar o crescimento da mamoneira BRS Energia, em função da salinidade da água de irrigação, em sistema de lisimetria. Os tratamentos foram constituídos dos níveis de salinidade da água de 0,12; 0,8; 1,6; 2,4; 3,2; 4,0 e 4,8 dS m-1, dispostos em delineamento inteiramente casualizado, com três repetições e quatro plantas por tratamento. Quinzenalmente foram avaliados, dos 20 até os 80 dias após a emergência, o crescimento e as taxas de crescimento absoluto e relativo da altura de plantas, diâmetro do caule e a área foliar das plantas. O crescimento avaliado pela altura, diâmetro do caule, área foliar e as taxas de crescimento absoluto e relativo de cada variável, diminuíram com o aumento da salinidade da água de irrigação, em todos os períodos estudados. As inibições foram respostas da elevação do nível salino do solo de não salino, para ligeiramente, moderadamente e fortemente salino.

Differences in Morphological, Physiological and Growth Traits between Two Endemic Subspecies of &amp;lt;i&amp;gt;Brassica rupestris&amp;lt;/i&amp;gt; Raf.: Implications for Their Conservation

The goal of this work was to analyze the phenological and physiological responses of Brassica rupestris Raf. subsp. hispida Raimondo & Mazzola and Brassica rupestris Raf. subsp. rupestris to environmental factors also in consideration of global change. We used seedlings of the two subspecies originated from wild plants from the natural habitats in Sicily and cultivated in the Botanical Garden of Rome. Leaf morphological and physiological traits and growth dynamic were analyzed as well as the response to an imposed water stress experiment. The results underlined a higher relative growth rate in plant height (RGRH, cm·cm-1·d-1) in B. rupestris subsp. rupestris also attested by the highest plant height (H, cm), leaf area (LA, cm2), specific leaf area (SLA, cm·g-1), total leaf area per plant (TLA, cm2) and total plant dry mass (PDM, g plant-1). Moreover, the significantly highest net photosynthetic rates (A, μmol CO2 m-2·s-1) during the study period of this subspecies was related to the high Chlorophyll content (Chl, SPAD units). B. rupestris subsp. rupestris was also the most tolerant subspecies to imposed water stress showing the highest relative water content (RWC, %), A and water use efficiency (WUE, μmol·mmol-1). </spa

고성 산불피해지에서 소나무 치수의 자연복원 패턴

산불 발생 이후 대부분의 지역에서 소나무보다는 참나무류로 천연갱신되는 패턴을 보인다. 그러나 능선부나 암반지대 등 척박한 곳에서는 소나무가 일부 생존하며, 때에 따라서는 임분을 형성하기도 한다. 따라서 본 연구는 산불피해지에서 능선부를 중심으로 소나무의 생장과 개체수를 조사하여 산불피해지에서 소나무의 천연갱신에 관한 기초자료를 제공하고자 수행되었다. 산불피해지에서 소나무 개체수의 변화는 1회 지표화 피해지인 5번 조사구에서는 산불 발생 후 초기 5년간 증가하는 패턴을 보여주었다. 이는 지표화에 의해 하층식생이 제거되고 지표화 피해로부터 생존한 개체로부터 종자가 지속적으로 유입되었기 때문으로 판단된다. 2회 전소화 피해지인 1, 2, 3, 그리고 4번 조사구의 경우 산불 발생 5년 이후부터 소나무 치수의 발생이 증가하는 패턴을 보였는데 이는 능선 근처에 소나무 잔존목이 존재하지 않아 종자의 유입이 어려워 소나무의 이입이 더뎠으나 시간이 경과함에 따라 토양 환경이 안정되고 종자를 생산하는 개체가 늘어 소나무 치수의 이입이 증가했을 것으로 사료된다. 소나무 수고의 상대 생장율은 임분에 관계없이 시간 경과에 따라 급격히 감소하는 경향을 보여주었으며, 이는 모든 조사구에서 공통적으로 나타난 결과이다. 따라서 산불피해지에서 자연 복원된 소나무의 수고 상대 생장율은 산불의 발생빈도나 형태와는 무관한 것으로 판단된다. 따라서 향후 개체수와 수고 생장속도에 영향을 끼치는 토양의 성질과 유실량, 그리고 주변 임분에서 자라는 참나무류의 생장에 관한 조사가 추가적으로 이루어져야 할 것이며, 한편, 생존한 주변 소나무 임분의 유전학적 동정을 통해 소나무 치수의 이입에 관한 연구가 이루어져야 할 것으로 판단된다. This study was conducted to determine the natural succession process after forest fire by comparing height, relative growth rates in height (RGH), and tree density of pine seedlings with different fire severity. In the area damaged by surface fire, tree density was highest during the first 5 years after fire. However, in the area damaged by crown fire, tree density rapidly increased during first 5 years after fire. Pine seedlings were found only on the place with ridges, barren soil, and the aspect of north. Annual height growth of pine seedlings was decreased with time in all study sites. The empty space in pine stands gradually decreased by the invasion of Quercus species. The forest fire altered the pine forest into oak forest rapidly. In contrast, pine seedlings invaded steadily on the oak forest in the rocky area or the area with ridges.

Demographic and height growth response of native broad-leaved deciduous tree saplings to overhead canopy release in a coastal Pinus thunbergii forest in Hokkaido, northern Japan

Prevention efforts to combat pine wilt disease must be instituted to avoid destruction of coastal forests in Hokkaido, northern Japan. We examine an alternative method involving the conversion of Pinus thunbergii forests to native broadleaf species through advancing their growth, but we have little knowledge about the response of advanced growth to overhead canopy release. To demonstrate the demographic and height growth response of advanced growth to the light change in a coastal Pinus thunbergii forest, canopy trees were removed and the sapling populations were monitored for 6 years. Inhibition in height growth caused by light increase was observed in Cerasus sargentii and Kalopanax septemlobus saplings. Especially in Kalopanax septemlobus, a remarkable decline was observed in the saplings growing in the darker positions which experienced light change. Therefore, large light changes should be carefully avoided for this species especially in the darker positions. In contrast, relative height growth rates of Quercus crispula and, especially, Quercus dentata increased with increasing light, and saplings tended to die in the darker positions. No dead trees of Sorbus commixta were observed during the study period. The saplings also showed good height growth even when under closed canopy. This species seems to be adaptive to a dark environment. Since Quercus dentata and Kalopanax septemlobus are the major components of the natural coastal forests in Hokkaido, gradual canopy release is available to foster advanced growth in coastal Pinus thunbergii forest, in accordance with the concept of density control in coastal forests.

Seedling Survival and Growth of Tree Species: Site Condition and Seasonality in Tropical Dry Forest Restoration

Restoring seasonally dry tropical forest is a worldwide priority, since it is the most threatened of all major tropical forest types. In Veracruz, Mexico, the dry forest has been reduced to fragments and fallows representing 7% of the original cover. Our objective was to determine the effect of site condition and seasonality on seedling survival and relative growth rate in height and diameter of selected native tree species. We studied plant performance during two dry and two rainy seasons and the effect of existent woody vegetation &gt; 1 m height. A total of 960 seedlings were transplanted: 40 individuals of six species (Cedrela odorata, Ceiba aesculifolia, Guazuma ulmifolia, Ipomoea wolcottiana, Luehea candida, Tabebuia rosea) in four fallows. Seedling survival and relative growth rate were monitored every four months during two years. Survival was higher in sites with more woody species richness, whereas relative growth rate in height was positively correlated with existent vegetation height. Relative growth rate was higher for all species and sites during the rainy season. In the site with less existent woody vegetation, seedling performance was poor and only Guazuma survived. Overall, Ceiba showed the highest survival rate (82-90%) and the lowest relative growth rate. Guazuma had a high survival (20-94%) and the highest relative growth rate; Cedrela showed the lowest survival (3-7%) and high relative growth rate. Our results suggest that site condition, seasonality, and tree species selection act together on seedling performance during early establishment. A vital implication in terms of ecological restoration is the importance of taking advantage of existent vegetation even if it is scarce.

Croissance compensatoire et stimulation de croissance chez Elytrigia juncea soumis à différents régimes de défoliation

Compensatory growth for defoliated plants is an issue still debated in literature, due to methodological weakness and lack of knowledge about its occurrence. In a green-house experiment, we applied three types of defoliation on Elytrigia juncea, a Poaceae species dominating costal foredunes. Responses to the different combinations of intensity and frequency of defoliation were assessed by measurements of final biomass of target species. Relative growth rates in height and number of leaves were also calculated, enable us to assess more accurately compensatory growth. An important growth stimulation was pointed out two weeks after a severe cut, and was still visible over the course of the experimentation without being able to induce overcompensation of growth. The occurrence of compensatory growth was pointed out only when plant tissues removed by cutting were added.