Soil Seed Bank Research Articles

Self‐regeneration of hairy vetch (Vicia villosa Roth) as affected by seedling density and soil tillage method in a semi‐arid agroecosystem

AbstractVicia villosa Roth is a forage legume with the capability for biological N fixation and natural reseeding, which could contribute to sustainability in semi‐arid regions. This study aimed to determine (i) the relationship between vetch density, seed production and spontaneous seed dispersal; (ii) the impact of the post‐dispersal tillage treatment over the soil seedbank dynamics; and (iii) potential predation of the seedbank by feral pigeons. A density range between 50 and 200 plants m−2 did not influence seed production or seed dispersal. Shallow disc tillage (SDT) clearly favoured self‐regeneration, resulting in higher amount of emerged seedlings during autumn compared to no tillage (NT). Based on observed emergence data, the percentage of emerged seedlings under SDT and NT were 38 and 6% of the seedbank, respectively, during 18 months after plot harvest. The lowest emergence values registered under NT could be associated with higher pressure from natural predators, soil‐borne pathogens, seed decay by ageing and false breaks. The feral pigeon (Columba livia var.) might be considered the main cause of vetch seedbank depletion in this study. Under controlled conditions, a single pigeon is able to consume, on average, between 184 and 768 seeds per day, depending on seed exposure and alternative food sources availability.

Interspecific variation in persistence of buried weed seeds follows trade‐offs among physiological, chemical, and physical seed defenses

Soil seedbanks drive infestations of annual weeds, yet weed management focuses largely on seedling mortality. As weed seedbanks increasingly become reservoirs of herbicide resistance, species‐specific seedbank management approaches will be essential to weed control. However, the development of seedbank management strategies can only develop from an understanding of how seed traits affect persistence.We quantified interspecific trade‐offs among physiological, chemical, and physical traits of weed seeds and their persistence in the soil seedbank in a common garden study. Seeds of 11 annual weed species were buried in Savoy, IL, from 2007 through 2012. Seedling recruitment was measured weekly and seed viability measured annually. Seed physiological (dormancy), chemical (phenolic compound diversity and concentration; invertebrate toxicity), and physical traits (seed coat mass, thickness, and rupture resistance) were measured.Seed half‐life in the soil (t 0.5) showed strong interspecific variation (F 10,30 = 15, p < .0001), ranging from 0.25 years (Bassia scoparia) to 2.22 years (Abutilon theophrasti). Modeling covariances among seed traits and seedbank persistence quantified support for two putative defense syndromes (physiological–chemical and physical–chemical) and highlighted the central role of seed dormancy in controlling seed persistence.A quantitative comparison between our results and other published work indicated that weed seed dormancy and seedbank persistence are linked across diverse environments and agroecosystems. Moreover, among seedbank‐forming early successional plant species, relative investment in chemical and physical seed defense varies with seedbank persistence. Synthesis and applications. Strong covariance among weed seed traits and persistence in the soil seedbank indicates potential for seedbank management practices tailored to specific weed species. In particular, species with high t 0.5 values tend to invest less in chemical defenses. This makes them highly vulnerable to physical harvest weed seed control strategies, with small amounts of damage resulting in their full decay.

The Soil Seedbank of Pasture Communities in Central Queensland Invaded by Parthenium hysterophorus L.

A study examining the composition and dynamics of the soil seedbank was conducted at two locations in central Queensland between December 2007 and May 2009. These two grassland communities were infested with parthenium weed (Parthenium hysterophorus L.), which had been present at both sites for at least 25 years. During the period of study, the seedbank varied between 5 962 and 16 206 seeds/m2 at the Clermont site and between 6 795 and 24 862 seeds/m2 at the Moolayember Creek site. Parthenium weed exhibited a very abundant and persistent seedbank, accounting for 80−87% of the seedbank at the Clermont site and 3−26% of the seedbank at the Moolayember Creek site. The species richness and species diversity of the seedbank, as well as the seed abundance of several native and introduced species, were higher at the Moolayember Creek site than at the Clermont site. The domination of the seedbanks by parthenium weed, especially at Clermont, suggests that the weed is having a substantial negative impact on seedbanks of native plant communities. The diversity of the seedbank at the Clermont site was found to be lower in comparison with that observed during an earlier study in 1995−1996, while the diversity at Moolayember Creek was found to have increased. Hence, the prolonged presence of parthenium weed may have substantially reduced the diversity of the seedbank at the Clermont site, while improved management practices may have increased diversity at the Moolayember Creek site.

The influence of substrates rates on the germination characteristic of a soil seed bank

Soil seed bank (SSB) is considered as an important way of vegetation restoration, it can fleetly achieved vegetation diversification and the course of succession when the topsoil mixed with planting substrates. In this paper, a greenhouse germination method was used to explore the effect on germination characteristic of soil seed bank by adding different inorganic substrates, such as activated carbon, perlite and vermiculite. The results showed that perlite and vermiculite can effectively promote the germination of soil seed bank, but also significantly promote Shannon-Wiener diversity index. When vermiculite mixed with the topsoil in 40%, the germination effect of soil seed bank was more obviously than other groups; at this time, the density of soil seed bank reached 6 X 105 plants/m2, Shannon Wiener diversity index reached 1.4354. Therefore, it was more conducive to improve the soil seed bank density and species diversity by adding 40% vermiculite in the topsoil.

Field emergence and the long‐term efficacy of control of Heracleum sosnowskyi plants of different ages in southern Poland

SummaryHeracleum sosnowskyi is one of the three so‐called tall or giant hogweeds currently invading Asia, Europe and North America. These plants are dangerous invasive weeds, causing severe skin injuries in humans and animals. In the present study, based on four field experiments, we assessed seedling emergence in the field and evaluated methods for the long‐term mechanical and chemical control of H. sosnowskyi of various ages (1–5 years old). The field experiments were set up in the mountainous regions of southern Poland, on soil not previously infested with H. sosnowskyi seeds. The results showed that the successful eradication of this species from an invaded area is possible. The results revealed that when no new flush of seeds is delivered to the soil seedbank, the longevity of H. sosnowskyi seeds is approximately five years, with the majority of seedlings emerging in the spring of the first year following sowing. Long‐term shoot cutting, particularly the intensity of this technique, is ineffective for the control of H. sosnowskyi. Cutting three times a year for five years resulted in an H. sosnowskyi control outcome of 42–97%. Total control of this weed is obtained either by cutting the roots of plants up to 5 years old at a depth of 15 cm or by continuous (5 years long) herbicide spraying three times during the vegetative season, using a tank mixture of glyphosate and flazasulfuron (1260 g a.i. glyphosate ha−1 + 50 g a.i. flazasulfuron ha−1).

Evidence for enemy release and increased seed production and size for two invasive Australian acacias

Summary Invasive plants are hypothesized to have higher fitness in introduced areas due to their release from pathogens and herbivores and the relocation of resources to reproduction. However, few studies have tested this hypothesis in native and introduced regions. A biogeographical approach is fundamental to understanding the mechanisms involved in plant invasions and to detect rapid evolutionary changes in the introduced area. Reproduction was assessed in native and introduced ranges of two invasive Australian woody legumes, Acacia dealbata and A. longifolia. Seed production, pre‐dispersal seed predation, seed and elaiosome size and seedling size were assessed in 7–10 populations from both ranges, taking into account the effect of differences in climate. There was a significantly higher percentage of fully developed seeds per pod, a lower proportion of aborted seeds and the absence of pre‐dispersal predation in the introduced range for both Acacia species. Acacia longifolia produced more seeds per pod in the invaded range, whereas A. dealbata produced more seeds per tree in the invaded range. Seeds were bigger in the invaded range for both species, and elaiosome: seed ratio was smaller for A. longifolia in the invaded range. Seedlings were also larger in the invaded range, suggesting that the increase in seed size results into greater offspring growth. There were no differences in the climatic conditions of sites occupied by A. longifolia in both regions. Minimum temperature was higher in Portuguese A. dealbata populations, but this difference did not explain the increase in seed production and seed size in the introduced range. It did have, however, a positive effect on the number of pods per tree. Synthesis. Acacia dealbata and A. longifolia escape pre‐dispersal predation in the introduced range and display a higher production of fully developed seeds per fruit and bigger seeds. These differences may explain the invasion of both species because they result in an increased seedling growth and the production of abundant soil seedbanks in the introduced area.

Evaluation of Herbicide Programs for Use in a 2,4-D–Resistant Soybean Technology for Control of Glyphosate-Resistant Palmer Amaranth (Amaranthus palmeri)

Two separate field experiments were conducted over a 2-yr period in Fayetteville, AR, during 2012 and 2013 to (1) evaluate POST herbicide programs utilizing a premixture of dimethylamine (DMA) salt of glyphosate + choline salt of 2,4-D in a soybean line resistant to 2,4-D, glyphosate, and glufosinate and (2) determine efficacy of herbicide programs that begin with PRE residual herbicides followed by POST applications of 2,4-D choline + glyphosate DMA on glyphosate-resistant Palmer amaranth. In the first experiment, POST applications alone that incorporated the use of residual herbicides with the glyphosate + 2,4-D premixture provided 93 to 99% control of Palmer amaranth at the end of the season. In the second experiment, the use of flumioxazin, flumioxazin + chlorimuron methyl, S-metolachlor + fomesafen, or sulfentrazone + chloransulam applied PRE provided 94 to 98% early-season Palmer amaranth control. Early-season control helped maintain a high level of Palmer amaranth control throughout the growing season, in turn resulting in fewer reproductive Palmer amaranth plants present at soybean harvest compared to most other treatments. Although no differences in soybean yield were observed among treated plots, it was evident that herbicide programs should begin with PRE residual herbicides followed by POST applications of glyphosate + 2,4-D mixed with residual herbicides to minimize late-season escapes and reduce the likelihood of contributions to the soil seedbank. Dependent upon management decisions, the best stewardship of this technology will likely rely on the use multiple effective mechanisms of action incorporated into a fully integrated weed management system.

Effect of grazing removal on aboveground vegetation and soil seed bank composition in sub-alpine grasslands of northern Iran

Background: Knowledge about vegetation and soil seed bank composition and the processes that contribute to vegetation recovery after the removal of heavy grazing is lacking in sub-alpine ecosystems.Aims: In order to assess the effects of large herbivores on above-ground vegetation (AGV) and soil seed bank (SSB) characteristics, intensively sheep-grazed areas were compared to adjacent areas where grazing had been removed 10 years previously in a sub-alpine grassland of northern Iran.Methods: A total of 40 4-m2 (2 m × 2 m) plots were established in each treatment, and soil samples were collected from each plot within a depth of 10 cm. Plant species composition was determined for each plot during the flowering stage of herbaceous species in June 2011. The seedling emergence method was used to estimate SSB composition.Results: A total of 45 species (23 annuals and 22 perennials) emerged from the soil samples of the grazed area, while the number of species emerged from the soil samples of the previously grazing area was 76 (37 annuals and 39 perennials). The removal of grazing led to a significant increase in species richness and seed density in the SSB. Species turnover of AGV was higher, and that of the SSB was similar for grazed areas compared with areas that were formerly grazed. Detrended correspondence analysis ordination of AGV composition showed a clearly separate structure between grazed plots and plots where grazing has been removed, while the segregation was less clear for SSB composition.Conclusions: We concluded that restoration of locally degraded sites cannot rely on the SSB when grazing is stopped simultaneously and unvegetated gaps are colonised by vegetative growth rather than by seed.

Invasive earthworms as seed predators of temperate forest plants

Soil seedbanks play a key role in forest plant communities, contributing to regeneration and acting as a refuge from seed predators. This study provides evidence that seeds entering the soil seedbank are vulnerable to granivory by invasive earthworms in temperate forests. Overall, 73 % of seeds of 6 ecologically important forest species were removed from the soil surface over 2 weeks in a Lumbricus terrestris microcosm experiment; 30 % vanished entirely, and presumably were destroyed. The invasive garlic mustard, Alliaria petiolata, was subject to the highest rates of removal. In contrast, results from a field exclosure experiment using 23 species of seed indicate that while seed predation by worms is still detectable, predation by rodents often may mask impacts of earthworms under natural conditions. Worms and rodents preferred different sizes of seeds: while seed predation by rodents was high in mid- to large-seeded species, earthworms tended to prefer smaller seeds. These findings suggest that although rodents are the main driver of seed predation, invasive earthworms may act as an additional ecological filter, and potentially may further influence the species composition of forest plant communities.

Tall Waterhemp (Amaranthus tuberculatus) and Palmer amaranth (Amaranthus palmeri) Seed Production and Retention at Soybean Maturity

Two of the most problematicAmaranthusspecies in soybean production today are tall waterhemp and Palmer amaranth. This study determined the percentage of tall waterhemp and Palmer amaranth seed that was retained by the weed at soybean maturity to assess the likelihood of using at-harvest weed seed control tactics for soil seedbank management. Palmer amaranth plants were collected from fields in Arkansas, Tennessee, Illinois, Missouri, and Nebraska, and tall waterhemp plants were collected from fields in Nebraska, Missouri, Wisconsin, and Illinois. Collected plants were assessed for at-harvest weed seed retention in 2013 and 2014. Within 1 wk of soybean maturity,Amaranthusplants were harvested and the loose soil and debris beneath the plants were swept into a pan with a hand broom to collect any shattered seed. Percent seed retention ranged from 95 to 100% for all states both years, regardless of species. There was a strong correlation between weed biomass (g) and total seed production (no. plant−1) in that the larger the plant, the more seeds it produced. However, there was no correlation between percent seed retention and weed biomass, which indicates that regardless of plant size and likely time of emergence, seed retention is high at the time of crop maturity. Overall, this study demonstrated that there is great opportunity for Palmer amaranth and tall waterhemp seed capture or destruction at soybean harvest. It is likely that nearly all of the seeds produced for bothAmaranthusspecies passes through the combine during harvest to be returned to the soil seedbank. Thus, there is continued need for research focused on developing and testing harvest weed seed control tactics that aim at reducing the soil seedbank and lowering risks for evolution of herbicide resistance.

Interference of the agrestal Helianthus annuus biotype with sunflower growth

SummaryThe Helianthus annuus taxon includes the wild (ruderal), weedy (agrestal) and volunteer biotypes, which may share space and time with the sunflower crop. The agrestal biotype is one of the most harmful weeds challenging the use of modern biotechnological tools in sunflower. The interference of the agrestal biotype was studied at a range of weed densities within a sunflower crop. The area of influence of one agrestal plant was estimated as a circular area of more than 2.5 m2. The agrestal biotype at 10.7 plants m−2 reduced the sunflower seed production by 66%, the seed weight by 41% and the yield by 80%. The agrestal biotype showed intermediate vegetative stage duration between sunflower and the ruderal biotype. The interference of the agrestal biotype would be due to its high initial growth rate, its larger leaf area and plant height. Some agrestal plants showed partial dehiscence at the sunflower harvest stage replenishing the soil seedbank with over 18 000 seeds m−2. The sunflower harvest operation and grain storage might be affected due to a fraction of agrestal plants remaining alive and moist when the crop reached harvest maturity. The results support the recommendation of preventing the entry of the agrestal biotype into crop production fields.

Analysis on Soil Seed Bank Diversity Characteristics and Its Relation with Soil Physical and Chemical Properties after Substrate Addition.

AimsConsidered as an essential measure in the application of soil seed bank (SSB) projects, the mixing of substrate and surface soil can effectively improve soil condition. This research is aimed at exploring the diversity characteristics of SSBs and the relationships between SSBs and soil properties.MethodsCanonical correspondence analysis (CCA) was adopted to describe the ordination of SSBs on soil properties’ gradients; multiple linear regressions were adopted to analyze the relationship between average growth height and soil properties, density and soil properties.ResultsExperimental groups of mixed substrate (the mixture of organic and inorganic substrates) had high diversity indexes, especially the Shannon-Wiener Index compared with those of single substrate. Meanwhile, a higher number of species and increased density were also noted in those of mixed substrate. The best test group, No.16, had the highest diversity indexes with a Shannon-Wiener of 1.898, Simpson of 0.633 and Pielou of 0.717, and also showed the highest density of 14000 germinants /m2 and 21 species. In addition, an improvement of the soil’s chemical and physical properties was noted when the substrates were mixed. The mixed substrate of turfy soil and perlite could effectively enhance the soil moisture content, whilst a mixed substrate of rice husk carbon and vermiculite could improve the content of available potassium (AK) and phosphorus (AP) and strengthen soil fertility. The germinated plants also reflected obvious regularities of ordination on soil factor gradients. Three distinct cluster groups were presented, of which the first cluster was distributed in an area with a relatively higher content of AK and AP; the second cluster was distributed at places with relatively higher soil moisture content; and the third cluster of plants didn’t show any obvious relationship with soil physical and chemical properties. Through CCA analysis, AK and AP were considered the most important soil factors to influence the SSB, which was illustrated in regression analysis with a high correlation coefficient when dependent values were growth height and density respectively. The linear regression equations with: growth height = 142.728 − 1.514TC + 30.218AP − 5.083TN + 10.839AK + 1.234mc; density = −68.216 − 4.609TC + 9.566AP − 35.492TN + 19.779AK − 1.591mc.were established by multiple linear regression.Conclusions(1) The mixed substrates showed a greater advantage for SSBs than single substrates, both in improving the number of species, density and diversity indexes. (2) The germinated plants reflected an obvious preference to different soil conditions, which different mixed substrates could improve accordingly. (3) AK, AP were important soil factors to influence SSBs, especially in the growth of plants and density.

Transgenic glyphosate-resistant canola (Brassica napus) can persist outside agricultural fields in Australia

In the last two decades the cultivation of transgenic crops has steadily increased worldwide. In Western Australia transgenic glyphosate-resistant canola (GR) has been cultivated since 2009. This study was conducted to examine the potential for transgene persistence outside agricultural fields after commercialization of GR crops. Propagule pressure, population fluctuations and reproductive output of GR canola plants have been assessed in semi-natural (roadside) and natural environments over consecutive years. The estimation of demographic parameters (plant survival and fecundity) suggest that GR canola has low likelihood to become invasive, as plants are subjected to biological and abiotic stressors likely limiting the fitness. This was particularly evident in a natural environment in which a propagule of 300 GR canola plants accidentally introduced by a wind storm could persist for three years before extinction. Thus, in natural areas GR canola populations did not show a positive population turnover and declined overtime. Conversely, on roadsides the significant correlation (r=0.975) between mean plant fecundity (seed rain) and the soil seedbank density in the following year suggests that local recruitment contributed to canola persistence for at least three years. As, no individual GR plants were found with stacked genes for multiple herbicide resistance we suggest that GR volunteer canola plants can be controlled by simple mixture of herbicide modes of action different to glyphosate although an integrated management including mechanical control operations would be the optimal strategy.

Response of soil seed bank to a prescribed burning in a subtropical pine–oak forest

Prescribed burning is a management instrument applied to reduce the risk of fire and favour revegetation. Our objective was to generate information about the dynamics of post-fire regeneration via the soil seed bank (SSB), for fire management in subtropical forests. Samples taken at soil depths of 0–3cm, 3–6 cm and 6–10 cm before and 5 h after a prescribed burn showed that the fire immediately increased the number of germinable seeds and species in a Mexican pine–oak forest. Most of the germinable seeds were from species in genera with small seeds exhibiting physical or physiological dormancy, and that are tolerant or require fire for germination. Fire increased the number of germinable seeds during the wet season and the number of species was greater in the area control at 0–6-cm soil depth after 1 year; so that the fire modified the SSB seasonal pattern. Species diversity was not altered and was dominated by perennial herbaceous and shrub species both before and 2 years after the fire. Although fire completely eliminated the aboveground biomass of the understorey vegetation, the SSB can promote regeneration and persistence of understorey vegetation following a prescribed surface fire of low severity for the ecosystem studied.

Old World Bluestem Seedling Emergence and Vegetative Cover Following Glyphosate Treatment

Old world bluestems (OWB) are perennial warm-season grasses introduced into the U.S. from parts of Asia, eastern Europe, Africa, and Australia. The two most common old world bluestem species found in Kansas are yellow bluestem (Bothriochloa ischaemum), otherwise known as King Ranch bluestem, and Caucasian bluestem (Bothriochloa bladhii). These grasses were introduced for soil conservation and forage production in arid regions of the southern Great Plains; however, in Kansas and elsewhere, they have escaped areas where planted and have been invading native rangelands and pastures that were old crop fields seeded back to native grasses. Efforts to control OWB in native rangelands and native seeded pasture have had short term success, but the abundant seed produced from mature OWB plants has resulted in a soil seedbank capable of producing high populations of new seedlings. However, the length of time that this seedbank is capable of producing new seedlings has received relatively little investigation. The goal of this project was to evaluate new OWB seedling emergence from the soil seedbank for two years following OWB control with glyphosate.

Relationships between fire severity and recruitment in arid grassland dominated by the obligate-seeding soft spinifex (Triodia pungens)

Fire intensity is recognised as an important driver of regeneration dynamics in forest and shrubland vegetation types, but its effects on recruitment processes in arid grasslands are poorly understood. Here, we used fire severity as a surrogate measure of fire intensity, and compared post-fire seedling recruitment from arid Triodia pungens (soft spinifex) plots burnt by low-severity experimental fires against those burnt by a high-severity wildfire. To explain T. pungens recruitment patterns, we also: (1) conducted a longitudinal depth distribution study of soil seedbank densities, and (2) carried out a lethal-temperature experiment on T. pungens seeds. High-severity burning was associated with reduced T. pungens recruitment compared with low-severity fire, and this relationship was attributed to the low lethal temperature thresholds of seeds and the adverse impacts of elevated soil temperatures during high-severity fire on the shallow soil seedbank. Among other species in the community, there were varied recruitment responses to fire severity. Overall, our results indicate that a strong link exists between fire severity and recruitment in arid spinifex grassland, though the association is variable among species, and dependent on the seedbank attributes, germination biologies and lethal-temperature thresholds of seeds of individual species.

Emergence Date Influences Growth and Fecundity of Palmer Amaranth in Cotton

Research was conducted in 2012 and 2013 in Fayetteville, AR to evaluate the impact of Palmer amaranth (Amaranthus palmeri (S.) Wats.) emergence date on plant biomass, height, and seed production as well as the corresponding influence on cotton (Gossypium hirsutum L.) biomass and yield. Palmer amaranth was evaluated in the presence and absence of cotton and when emergence was delayed in cotton (0, 2, 4, 6, 8, and 10 wk). Seed production per plant was reduced by a greater extent in the presence of cotton, compared to the absence of cotton. Palmer amaranth plants emerging 10 wk after cotton were able to produce on average 880 seed per plant, which is a sufficient amount to replenish a soil seedbank. The late-emerging plants competing with cotton were smaller in size than earlier emerging plants. Seed production in the presence of cotton was correlated with Palmer amaranth biomass production (r2 = 0.63). Furthermore, the later-emerging cohorts responded to the presence of cotton by producing less biomass more so than a reduction in plant height with delayed emergence. This research shows that Palmer amaranth cohorts emerging as late as 10 wk after cotton emergence must be removed to prevent weed seed production.

When is the Best Time to Emerge—II: Seed Mass, Maturation, and Afterripening of Common Waterhemp (Amaranthus tuberculatus) Natural Cohorts

Field studies were conducted to determine the effect of emergence timing on the fitness of the next generation as represented by seed mass, maturation, and afterripening of common waterhemp cohorts. Five natural cohorts were documented both in 2009 and 2010. Different maternal environments resulting from varied cohort emergence timings did not influence seed maturation time and seed mass, but had an inconsistent effect on seed afterripening. Here are our major findings. (1) Waterhemp cohorts needed similar amounts of time to generate viable seeds (20 to 27 d after flower initiation) and the seeds produced were of similar size (2.0 to 2.35 g), and (2) waterhemp has strong primary dormancy that may be released within 4 mo during the afterripening process, depending on the dormancy level. Seeds produced by later cohorts were more sensitive to the afterripening period, suggesting more flexibility in life strategy. Seeds from the 2009 cohorts had similar afterripening patterns; newly harvested seeds had strong primary dormancy (&lt;10% germination), which was gradually released during dry storage and reached the maximum germination (&gt;80%) rate 4 mo after harvest (MAH). However, germination then dropped to 40% 6 and 8 MAH, suggesting the induction of secondary seed dormancy. Strong primary dormancy at harvest for 2010 seeds was sustained in dry afterripening, perhaps because of higher dormancy level, which was the result of less-favorable parental environments brought by 10 to 30 times higher population densities and 2.5 to 5 times higher accumulative precipitation than in 2009 (see Wu and Owen 2014). We also tested the soil seed-bank seed population densities for each waterhemp cohort and found that early cohorts greatly influenced the seed population densities at the soil surface level and the turnover rate of the soil seed bank. Results from this research will provide insights into better management of waterhemp, targeting a better understanding of the seed bank.

Hairy Vetch Seedbank Persistence and Implications for Cover Crop Management

Hairy vetch (Vicia villosa Roth) is a fast‐growing, winter‐hardy annual legume that is well suited for summer annual grain rotations because it fixes N2, reduces erosion, and suppresses weeds. Utilization of hairy vetch as a cover crop has been limited due to producer concerns regarding its potential to become a weed in subsequent crops. Hairy vetch weediness is attributed to its hard seed, a physical dormancy trait common to Vicia species. A 2‐yr field experiment was conducted in Pennsylvania and Maryland to characterize the effects of mechanical scarification and burial depth on seedbank dynamics using two cultivars. Field and laboratory measurements were conducted to determine seedbank fate: seedling emergence, seedbank persistence, and seedbank loss. Hairy vetch emergence and persistence in the soil seedbank varied considerably across cultivars, years, and study locations. Scarification completely eliminated seedbank persistence 6 mo after burial but probably reduced viability and stand establishment in some cases. Among unscarified seed treatments, seedbank persistence ranged from &lt;1 to 7% 6 mo after burial. Burial of seed at 15 cm resulted in decreased seedling emergence and increased seedbank loss in comparison to the 3‐cm burial depth. Among treatments, seedling emergence ranged from 36 to 84% at the 3‐cm depth and 7 to 46% at the 15‐cm depth. These results indicate that mechanical scarification is a potential strategy for managing hairy vetch seedbank persistence and warrants further investigation. Tillage may also be effective for decreasing hairy vetch seedbanks when coupled with other management tactics.

Seedbank Potential of Chinese Tallow Tree (Triadica sebifera) in a Texas Bottomland Hardwood Forest

ABSTRACT: Chinese tallow tree (Triadica sebifera) is arguably one of the most deleterious exotic invasive plants in the southern United States, where it alters ecosystem structure and function, especially near the Gulf Coast. Chinese tallow continues to expand into riparian floodplain forests, which likely facilitate regional invasion by dispersing seeds during seasonal flooding and providing corridors of favorable habitat. We attempted to estimate existing Chinese tallow soil seedbank presence and density in a bottomland hardwood forest located at Old Sabine Bottom Wildlife Management Area (OSBWMA) in northeastern Texas, where heavy infestation has not occurred to date, though mature seed-bearing trees are present regionally. No Chinese tallow seeds were detected across the study area, despite the occurrence of mature, seed-bearing plants on adjacent properties. Based on this lack of detected seeds, combined with the lack of observed Chinese tallow plants at OSBWMA, it appears the species continues to oc...