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1.
To assess the effects of different planting systems on early performance (survival, shoot emergence time, number of shoots, maximum shoot height and biomass shoot production) of willow, cuttings of varying lengths were planted horizontally at different depths and compared with vertically planted cuttings. Cutting lengths of (i) 25–200 cm and (ii) 7–21 cm were studied in a field experiment and in a box experiment, respectively. Shorter cuttings planted deeper had a lower survival rate and emerged a few days later compared to longer cuttings planted shallower. The performance was considerably higher at the apical part of the cuttings, regardless of cutting length. Longer cuttings planted shallow had a higher performance. Vertically planted cuttings produced more biomass and shoots per length unit than horizontally planted cuttings. We conclude that planting systems based on the use of longer horizontally planted cuttings would probably lead to an uneven establishment and gaps in the stand caused by apical dominance. Also, to achieve the same performance, the need of planting material would be considerably higher compared to systems with vertically planted cuttings. To obtain a fast and more even early establishment of willows, we recommend the use of vertically planted cuttings with a length of at least 20 cm. If cuttings are planted horizontally, they should not be planted deeper than 5 cm.  相似文献   

2.
A simulated flooding experiment was conducted to evaluate the effects of seasonal flooding on the plant Salix triandroides from the Dongting Lake wetlands in China. The morphology, photosynthetic activity, and anatomy of cuttings in three water conditions (?40 cm, water level 40 cm below soil surface; 0 cm, water level 0 cm at the soil surface; and 40 cm, water level 40 cm above soil surface) and two lights conditions (full sunlight and 10% sunlight) were measured. Plants had a higher survival ratio and biomass accumulation in full sunlight than in 10% sunlight when the water level was ?40 and 0 cm, but there was no difference between these parameters in cuttings grown under the two light conditions in the 40 cm water treatment. In full sunlight, a lower survival ratio and reduced biomass were observed with increasing water level. The same trend was also seen for survival ratio in 10% sunlight. However, there was no difference in biomass among the three water levels in 10% sunlight, except for leaf weight. Branch height, leaf number, adventitious root length, and adventitious root number were different in the three water levels and two light conditions. In water levels of ?40 and 0 cm, plants had lower chlorophyll contents in full sunlight than in 10% sunlight. In full sunlight, there was no difference in chlorophyll content between the water levels, while in 10% sunlight, lower chlorophyll content was observed in ?40 cm than in 0 cm water. Photosynthetic rate, stomatal conductance, and transpiration rate decreased, but water-use efficiency increased in reduced light at all three water levels. Additionally, plants had higher porosity in 40 cm water than in ?40 and 0 cm conditions. Based on the reduced plant growth in the 10% sunlight condition and decreased survival in the 40 cm water level, we conclude that low light significantly decreased plant acclimation to incomplete submergence and that high water levels induced dormancy in the cuttings. Therefore, the height of cuttings used for forestation or reforestation is an important consideration for mitigating the negative effects of seasonal flooding on the survival and growth of S. triandroides in Dongting Lake wetlands.  相似文献   

3.
A field study was conducted at Little Topashaw Creek in northern Mississippi, aimed at expanding the limited database on the survivorship of Salix nigra (black willow) cuttings planted on riparian restoration sites. We tested the hypothesis that sediment moisture availability (deficit, excess) as mediated by sediment texture and depth to the prevailing water table is a major factor governing black willow survival during the initial stage of establishment following transplanting. Replicated plots were established across elevational gradients and a range of soil texture. Each plot contained 16 planted cuttings (2.5 cm diameter × 2.5 m length). Plot depth to water table, soil texture, and soil redox potential were measured. Plant gas exchange, leaf chlorophyll content, growth, and survival were monitored periodically over two growing seasons. Survival was best at low elevation compared to cuttings planted at mid- and high elevations. Poor survival and growth were noted for cuttings that encountered sediment moisture deficits in plots with coarse texture while the best cutting survival was recorded for intermediate sand content plots. Results indicated that plot location on the bank and soil texture are two important factors that influence riverbank restoration success. Therefore, any riparian restoration plan should include careful assessment of these factors prior to undertaking such efforts.  相似文献   

4.
To assess the effects of cutting phenology on early growth performance of three willow clones grown under different weed treatments and planting dates, freshly harvested (non-dormant) and cold-stored (dormant) cuttings from willow clone Tora, Jorr, and Olof were planted in bucket experiment outdoors in central Sweden on five planting dates (May–June 2013) with or without a model weed (spring barley). Non-dormant cuttings sprouted faster than dormant cuttings when planted early in the season. For cuttings planted later in the season, bud sprouting was affected only by willow clone. Aboveground biomass production was affected by cutting phenology, planting date, clone, and weed treatment. When planted on May 3 and May 10, biomass produced from non-dormant and dormant cuttings did not differ, while willows grown from dormant cuttings produced 59% more aboveground biomass than willows grown from non-dormant cuttings when planted on May 24–June 16. Tora produced on average 12% more biomass than Jorr and Olof, and weed competition reduced aboveground biomass production on average with 36%. The ability of willow to suppress weeds (WSA) was 26 (non-dormant cuttings) and 12% (dormant cuttings) higher for willows planted on May 3 compared with WSA of willows grown from cuttings planted later in the season. The ability to tolerate competition from weeds (WT) was 51 and 52% lower for willows grown from non-dormant and dormant cuttings planted late in the season compared with WT of willows planted earlier in the season. We conclude that planting with long-term cold storage of willow cuttings can be replaced with planting freshly harvested cuttings when planting is performed in early season, and that weed competition strongly reduces biomass production. Weed control during the establishment phase is crucial in order to maximize willow biomass production.  相似文献   

5.
Growth, biomass, and survival of bald cypress (Taxodium distichum [L.] Richard), water tupelo (Nyssa aquatica L.), black willow (Salix nigra Marshall), and button bush (Cephalanthus occidentalis L.) were examined in a 3 times 3 factorial experiment varying water temperatures (AMBIENT, MID, and HIGH [~40 C]) and water levels (DRAINED, SATURATED, and FLOODED). Stem diameter and height, biomass, and survivorship for water tupelo and bald cypress were all reduced by the HIGH/FLOODED treatment. Black willow growth had the greatest variability among nonlethal flooding and temperature treatments, and achieved the greatest biomass of the four species. In the HIGH/FLOODED treatment, however, only 47% of the black willow seedlings survived and stem diameter, height, and biomass of survivors were greatly reduced. Button bush had intermediate variability of growth to the nonlethal treatments as compared to the other study species. Survival of button bush seedlings in the HIGH/FLOODED treatment was high (87%), but root biomass of the survivors was reduced. Interspecific differences in growth, biomass, survivorship, and morphological characteristics existed among these swamp species to experimental conditions. These responses may help explain vegetation patterns in a thermally impacted swamp.  相似文献   

6.
The vegetation of wetlands show strong zonation patterns, but the mechanisms determining these patterns are not fully understood. In the present study, growth and morphological responses to a water level gradient (–20 cm (i.e. water level 20 cm below soil surface), –10 cm, 0 cm, 10 cm, 20 cm) were compared between a higher elevation plant (Imperata cylindrica) and a lower elevation plant (Carex brevicuspis) in the Dongting Lake wetlands of China. For both species, the aboveground, belowground, and total biomass were greater at –10 cm than at any other water level.. However, when the water level increased from –10 cm to 0 cm, there was a greater decrease in the biomass of I. cylindrica than in that of C. brevicuspis. Plant height, tiller number, leaf length, leaf width and leaf area showed greater variation along the water level gradient in I. cylindrica than in C. brevicuspis. Generally, with increasing water level, root length, rhizome number, and adventitious root biomass and number all decreased in I. cylindrica. However, in C. brevicuspis, neither the rhizome number nor the primary adventitious root biomass differed significantly among the five water levels. These results indicate that I. cylindrica have a lower tolerance for flooding and higher water sensitivity than C. brevicuspis and these differences may explain why I. cylindrica is found at relatively higher elevations that are not prone to flooding, while C. brevicuspis is found at comparatively lower elevations in the Dongting Lake wetlands.  相似文献   

7.
In May 2004, 400 tree seedlings of seven different species found on tree islands in the Florida Everglades were planted at different elevations along five transects on eight newly constructed tree islands, four with and four without limestone cores. Seedlings suffered between 40 and 85% mortality during the first 120 days, the period with the lowest water levels. Ilex cassine L., Salix caroliniana Michx., Chrysobalanus icaco L., and Annona glabra had the highest number of surviving seedlings, whereas Magnolia virginiana L., Myrica cerifera L., and Acer rubrum L. had the fewest. During the remainder of the study, water levels were mostly higher and sometimes covered the entire islands for months at a time. After 220 days, nearly all seedlings of M. virginiana and My. cerifera had died. At the end of the study, seedlings of I. cassine and A. glabra had the highest survivorship rates. Seedling biomass of C. icaco and I. cassine was greatest at the highest elevations, whereas seedlings of A. glabra had similar biomass at all elevations. Seedling survivorship was not statistically different between islands with and without limestone cores; however, when seedlings of all species were combined, island core type was significantly different for aboveground biomass, seedling height, and canopy width. Because of the higher survivorship under both low and high water conditions, A. glabra , I. cassine , and S. caroliniana are the most suitable species for establishing tree species on restored tree islands in the Everglades.  相似文献   

8.
To evaluate the effects of weed competition and nitrogen fertilization on the early growth performance of willow, cuttings of the clone Tora (Salix schwerinii x S. viminalis) were planted in buckets together with model weeds (spring barley or white mustard) sown 15, 26, and 30 days after willow planting. The buckets were fertilized with 30 or 90 kg N ha?1. Willow with weeds sown after 15 days produced less biomass and smaller leaf area and had a lower maximum shoot height compared to willow planted without weeds and willow with weeds sown after 26 or 30 days. Fertilization with 90 kg N ha?1 gave higher willow biomass production in willow with weeds sown after 26 or 30 days. Type of model weed had no effect on willow performance. Weed biomass and maximum shoot height were higher in weeds planted without willows compared to the willow-weed mixtures. A high nitrogen level gave more weed biomass when planted without willows and in the willow-weed mixture with weeds sown after 15 days. We conclude that for the given high density of willow, competition from weeds emerging soon after willow planting had strong effect on early production. Furthermore, if there is a risk of weed infestation, fertilization should be delayed.  相似文献   

9.
The large river swamps of Louisiana have complex topography and hydrology, characterized by black willow (Salix nigra) dominance on accreting alluvial sediments and vast areas of baldcypress (Taxodium distichum) deepwater swamps with highly organic substrates. Seedling survival of these two wetland tree species is influenced by their growth rate in relation to the height and duration of annual flooding in riverine environments. This study examines the interactive effects of substrate, hydroperiod, and nutrients on growth rates of black willow and baldcypress seedlings. In a greenhouse experiment with a split-split-plot design, 1-year seedlings of black willow and baldcypress were subjected to two nutrient treatments (unfertilized versus fertilized), two hydroperiods (continuously flooded versus twice daily flooding/draining), and two substrates (sand versus commercial peat mix). Response variables included height, diameter, lateral branch count, biomass, and root:stem ratio. Black willow growth in height and diameter, as well as all biomass components, were significantly greater in peat substrate than in sand. Black willow showed a significant hydroperiod–nutrient interaction wherein fertilizer increased stem and root biomass under drained conditions, but flooded plants did not respond to fertilization. Baldcypress diameter and root biomass were higher in peat than in sand, and the same two variables increased with fertilization in flooded as well as drained treatments. These results can be used in Louisiana wetland forest models as inputs of seedling growth and survival, regeneration potential, and biomass accumulation rates of black willow and baldcypress.  相似文献   

10.
Abstract

Phyto-recurrent selection is an established method for selecting tree genotypes for phytoremediation. To identify promising Populus (poplar) and Salix (willow) genotypes for phytotechnologies, our objectives were to (1) evaluate the genotypic variability in survival, height, and diameter of poplar and willow clones established on soils heavily contaminated with nitrates; and (2) assess the genotypic stability in survival and diameter of selected poplar clones after one and eleven growing seasons. We tested 27 poplar and 10 willow clones planted as unrooted cuttings, along with 15 poplar genotypes planted as rooted cuttings. The trees were tested at an agricultural production facility in the Midwestern, United States. After 11 growing seasons, using phyto-recurrent selection, we surveyed survival and measured the diameter of 27 poplar clones (14 unrooted, 13 rooted) that were selected based on superior survival and growth throughout plantation development. Overall, willow exhibited the greatest survival, while poplar had the greatest height and diameter. At 11 years after planting, superior clones were identified that exhibited above-average diameter growth at the establishment- and rotation-age, most of which had stable genotypic performance over time. Selection of specific clones was favorable to genomic groups, based on the geographic location and soil conditions of the site.  相似文献   

11.
Effects of flooding on survival and growth of three different types of Nuttall oak (Quercus texana Buckl.) seedlings were observed at the end of third and fifth growing seasons at Yazoo National Wildlife Refuge, Mississippi, U.S.A. Three types of seedlings were planted in January 1995 in a split‐plot design, with four replications at each of two elevations on floodprone, former cropland in Sharkey clay soil. The lower of the two planting elevations was inundated for 21 days during the first growing season, whereas the higher elevation did not flood during the 5‐year period of this study. The three types of 1‐0 seedlings were bareroot seedlings, seedlings grown in containers (3.8 × 21–cm plastic seedling cones), and container‐grown seedlings inoculated with vegetative mycelia of Pisolithus tinctorius (Pers.) Coker. Survival of all the three seedling types was greatest at the lower, intermittently flooded elevation, indicating that drought and related effects on plant competition were more limiting to seedling survival than flooding. At the lower elevation, survival of mycorrhizal‐inoculated container seedlings was greater than that of noninoculated container seedlings. Survival among bareroot seedlings and inoculated container seedlings was not significantly different at either elevation. At the higher, nonflooded elevation, however, bareroot seedling survival was greater than the survival of container seedlings without inoculation. Differences were significant among the inoculated and the noninoculated container seedlings, with higher survival of inoculated seedlings at both elevations, though differences were only significant in year 3. At the end of the fifth year, height of bareroot seedlings was significantly greater than the heights of both types of container‐grown seedlings at both planting elevations. Because seedlings grown in the plastic seedlings cones did not survive better than the bareroot seedlings at either planting elevation, the bareroot stock appear to be the economically superior choice for regeneration in Sharkey soil.  相似文献   

12.
We quantified the physiological responses of black willow to four soil moisture regimes: no flooding (control, C), continuous flooding (CF), periodic flooding (PF), and periodic drought (PD). Stomatal limitation was one of the factors that led to the reduced photosynthetic capacity in CF cuttings. Under PD, stomatal closure, decreased leaf chlorophyll content, and increased dark fluorescence yield contributed to photosynthetic decline. CF cuttings accumulated the lowest shoot biomass while the final height and root growth were most adversely affected by PD. PF cuttings tended to allocate more photoassimilates to root growth than to shoots.  相似文献   

13.
A common approach to re‐establishing cottonwood–willow habitat along regulated rivers is through installing dormant, rootless cuttings, yet there is little published information exploring floodplain characteristics that optimize growth of southwestern riparian willows planted in this manner. The goal of this project was to evaluate relationships between growth attributes of Salix exigua and soil texture and soil water availability. Monitoring plots were established in five willow swales planted with dormant S. exigua cuttings along the banks of the Middle Rio Grande in central New Mexico. Data analysis revealed significantly higher aerial cover, height, and stem density for S. exigua plants installed in plots with intermediate levels (15–25%) of fine textured soils distributed through the soil profile. Similar relationships were found in relation to soil water availability. Regression analysis of percent fines and available water at different depth increments provided limited explanation of variability in willow growth attributes at different plots. Findings indicate that S. exigua plants established from cuttings can achieve heights and aerial cover values similar to naturally established willow bars if the floodplain soil profile contains intermediate levels of fine textured soils and the maximum depth to groundwater is within 1.5 m of the ground surface. Where sites are dominated by coarse sand, S. exigua growth may be improved if maximum depth to groundwater is within 1 m of the ground surface.  相似文献   

14.
Black willow (Salix nigra) cuttings are used for streambank stabilization where they are subjected to a range of soil moisture conditions including flooding. Flooding has been shown to adversely impact cutting performance, and improved understanding of natural adaptations to flooding might suggest handling and planting techniques to enhance success. However, data assessing the root aeration in adventitious roots that are developed on cuttings of woody species are scant. In addition, it appears that no data are available regarding aeration of the root system under partially flooded conditions. This experiment was designed to examine the effects of continuous flooding (CF) and partial flooding (PF) on aerenchyma formation and radial oxygen loss (ROL) in black willow cuttings. Photosynthetic and growth responses to these conditions were also investigated. Under laboratory condition, replicated potted cuttings were subjected to three treatments: no flooding (control, C), CF, and PF. Water was maintained above the soil surface in CF and at 10 cm depth in PF. Results indicated that after the 28-d treatments, root porosity ranged between 28.6% and 33.0% for the CF and C plants but was greater for the PF plants (39.2% for the drained and 37.2% for the flooded portions). A similar response pattern was found for ROL. In addition, CF treatment led to decreases in final root biomass and root/shoot ratio. Neither CF nor PF had any detectable adverse effects on plant gas exchange or photosystem II functioning. Our results indicated that S. nigra cuttings exhibited avoidance mechanisms in response to flooding, especially the partially flooded condition which is the most common occurrence in riparian systems.  相似文献   

15.
Phragmites or Common Reed (Phragmites australis) is a tall rhizomatous cosmopolitan grass. While native to Australia, it can be invasive in wetlands, forming dense monocultures and reducing their ecological integrity. We assessed the potential for the cutting of Phragmites reeds prior to planting to promote the establishment of indigenous shrubs that might ultimately outcompete Phragmites. We established ten 5 m × 5 m quadrats in an area dominated by Phragmites, brush‐cut the reeds to ground level in five of them and left five uncut as controls. Within each quadrat, we planted 20 plants (~40 cm tall) of each of five indigenous shrub species, unguarded (4 plants/m2). We surveyed the plants one month after planting and annually for the following four years for survival, height and browsing damage. Browsing damage to plants was common (>50%) and unaffected by cutting. After four years, overall plant survival rates were ~25% and mean plant heights for the five shrub species ranged between 120 and 174 cm. Cutting of Phragmites had no positive effect on plant survival or height. In fact, two Melaleuca species grew taller in the uncut quadrats. Cutting of Phragmites reed beds prior to planting is unlikely to promote the establishment of woody plantings. However, planting within established Phragmites with or without prior brush‐cutting is worthy of further trialling as a potential tool for reinstating native diversity at Phragmites‐dominated sites.  相似文献   

16.
We quantified the physiological responses of black willow to four soil moisture regimes: no flooding (control, C), continuous flooding (CF), periodic flooding (PF), and periodic drought (PD). Stomatal limitation was one of the factors that led to the reduced photosynthetic capacity in CF cuttings. Under PD, stomatal closure, decreased leaf chlorophyll content, and increased dark fluorescence yield contributed to photosynthetic decline. CF cuttings accumulated the lowest shoot biomass while the final height and root growth were most adversely affected by PD. PF cuttings tended to allocate more photoassimilates to root growth than to shoots.This revised version was published online in March 2005 with corrections to the page numbers.  相似文献   

17.
Species and hybrids between species belonging to the genera Populus (poplar) and Salix (willow) have been used successfully for phytoremediation of contaminated soils. Our objectives were to: 1) evaluate the potential for establishing genotypes of poplar and willow on soils heavily contaminated with petroleum hydrocarbons and 2) identify promising genotypes for potential use in future systems. We evaluated height, diameter, and volume after first year budset by testing 20 poplar clones and two willow clones. Unrooted cuttings, 20 cm long, were planted in randomized complete blocks at 0.91- x 0.91-m spacing at Gary, IN, USA (41.5 degrees N, 87.3 degrees W). Four commercial poplar clones (NM6, DN5, DN34, and DN182) were planted as 20- and 60-cm cuttings. Sixty-cm cuttings exhibited greater height and diameter than 20-cm cuttings; however, we recommend continued use and testing of different combinations of genotype and cutting length. We identified promising genotypes for potential use in future systems and we recommend allocating the majority of resources into commercial poplar clones, given their generalist growth performance. However, further utilization and selection of experimental clones is needed. Specific clones rather than genomic groups should be selected based on the geographic location and soil conditions of the site.  相似文献   

18.
实验设置对照、浅淹(水位高出土壤表面5cm)和深淹(水位高出土壤表面20cm)3种处理,研究了淹水深度对互叶白千层幼苗的气体交换、叶绿素荧光和生长状况的影响。研究结果表明,随着淹水深度的增加,互叶白千层受到的胁迫程度有所增强。经过270d的淹水处理,浅淹组和深淹组的株高和生物量有所下降,分别为对照的90.86%、64.58%和74.52%、36.46%。浅淹组植株叶绿素含量、净光合速率、气孔传导率和蒸腾速率略有下降,分别为对照的95.39%、94.26%、90.02%和88.94%。深淹组植株在淹水后180d内上述参数显著下降,分别为对照的79.44%、73.54%、61.79%和71.46%,随后逐渐接近对照组。浅淹组PSⅡ的最大光化学量子效率(Fv/Fm)比较稳定,与对照组基本相同。深淹组在淹水后150d内Fv/Fm稍有下降,随后恢复到对照水平。浅淹组植株光化学淬灭系数(qP)稍有下降,非光化学淬灭(NPQ)略有上升,分别为对照的96.63%和105.66%。深淹组植株在淹水后120d内qP显著下降,NPQ明显上升,分别为对照的94.51%和126.66%,随后逐渐接近对照组。另外,淹水过程中,互叶白千层形成不定根和产生发达的通气组织,淹水植株的根孔隙度显著高于对照。  相似文献   

19.
Species zonation patterns across tidal gradients in mangrove forests are formed by successful seedling establishment and maintained by replacement of adults by conspecific seedlings. These two processes rarely have been examined experimentally in neotropical mangal. We studied survivorship and growth of seedlings of two species of mangrove, Rhizophora mangle L. and Avicennia germinans (L.) Steam, across a tidal gradient in Belize, Central America. Propagules of each species were planted in common gardens at tidal elevations corresponding to lowest low water (LLW), mean water (MW), and highest high water (HHW). Sixty-nine percent of Rhizophora seedlings planted at MW and 56% of those planted at LLW survived 1 year. Forty-seven percent of MW Avicennia seedlings also survived 1 year. No individuals of either species survived at HHW, and neither did any LLW Avicennia seedlings. Among the surviving Rhizophora seedlings, LLW seedlings grew more rapidly in terms of height, diameter, leaf production, and biomass than did MW seedlings. Insect herbivory was twice as high on MW seedlings as on LLW Rhizophora seedlings. We also examined the response of established Rhizophora seedlings to experimental removal of the adult Rhizophora canopy. Seedlings in canopy removal areas had higher survivorship, grew twice as fast, produced more leaves, and had less than half the herbivory of seedlings growing beneath an intact canopy. These results provide insights into underlying causes and maintenance of zonation in Caribbean mangrove forests.  相似文献   

20.
Black willow (Salix nigra) uses periodic flood events for dispersal of vegetative propagules, subjecting them to periods of soaking before their deposition along the streambank. It was hypothesized that this life history trait results in optimal conditions for willow growth and survival. To test this hypothesis, a greenhouse experiment was conducted using 1.2‐m‐long black willow cuttings (posts) with a basal diameter of 5 cm. Cuttings were subjected to three soaking treatments (0, 3, and 10 days) and then grown under four soil moisture regimes (control, drought, permanently flooded, and intermittently flooded). Growth, biomass, and survival were recorded. Results showed that soaking posts for 10 days was most beneficial in the control soil moisture regime, enhancing root, shoot, leaf, and total biomass production. Shoot abundance and growth were also enhanced by 10 days of soaking in the control and permanently flooded moisture regimes. Finally, survival increased significantly in control and drought moisture regimes in response to the 10‐day soaking treatment. Results clearly demonstrated that soaking had significant effects on willow post success when evaluated across all soil moisture regimes. Posts subjected to the 10‐day soaking treatment consistently had greatest growth and biomass and displayed a doubling of the survival rate. Therefore, soaking willow cuttings before planting is a simple, inexpensive technique that may be used to bolster streambank restoration success.  相似文献   

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