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Author: Kristin Anne Weathers Publisher: ISBN: 9781303712197 Category : Erodium Languages : en Pages : 109
Book Description
Three studies were conducted to investigate effects of invasive Erodium species on re-establishment of native species in the California coastal sage scrub (CSS) plant community, and how both chemical and non-chemical techniques might be used to reduce Erodium and increase success of restoration efforts. First, the effects of a range of Erodium densities were tested on the establishment of native shrubs and forbs in two experimental sites, one a seeding experiment and the other a weeding experiment. Analyses were done to detect a threshold value where Erodium density decreased the establishment of the native species, and showed that Erodium species inhibited the establishment of native shrubs at about 66 Erodium plants/m2 . Erodium species often germinate at very high densities (thousands of plants/m 2 ), indicating land managers will often need to actively control Erodium species densities in order to restore CSS vegetation after disturbance. Second, varying treatments of the non-chemical agricultural technique of solarization were tested without irrigation, as supplementing water may not be possible in some wildland situations. Laying sheets of clear plastic over tilled soil during the hot summer months reduced invasive annuals the most of all the treatments, even without the addition of water. Third, chemical control experiments tested a variety of herbicides with different modes of action and at varying rates at two sites. Some herbicides labeled as grass-specific also have activity on Erodium species but do not damage most CSS native forbs and shrubs, and were tested in a variety of concentrations. Chemicals tested in this study did not provide season-long control of Erodium species at rates allowed by the label, but one above-label rate proved effective. Multiple applications of herbicides with this mode of action (e.g., fluazifop) within approved rates should be tested to determine efficacy on Erodium. The broadleaf-selective chemical triclopyr provided the best control but will have to be used with caution in the CSS community as it also has activity on native shrubs and forbs. The broad spectrum herbicide glyphosate had good control at one site, but the second site had germination of a second cohort of Erodium after the first cohort was sprayed.
Author: Kristin Anne Weathers Publisher: ISBN: 9781303712197 Category : Erodium Languages : en Pages : 109
Book Description
Three studies were conducted to investigate effects of invasive Erodium species on re-establishment of native species in the California coastal sage scrub (CSS) plant community, and how both chemical and non-chemical techniques might be used to reduce Erodium and increase success of restoration efforts. First, the effects of a range of Erodium densities were tested on the establishment of native shrubs and forbs in two experimental sites, one a seeding experiment and the other a weeding experiment. Analyses were done to detect a threshold value where Erodium density decreased the establishment of the native species, and showed that Erodium species inhibited the establishment of native shrubs at about 66 Erodium plants/m2 . Erodium species often germinate at very high densities (thousands of plants/m 2 ), indicating land managers will often need to actively control Erodium species densities in order to restore CSS vegetation after disturbance. Second, varying treatments of the non-chemical agricultural technique of solarization were tested without irrigation, as supplementing water may not be possible in some wildland situations. Laying sheets of clear plastic over tilled soil during the hot summer months reduced invasive annuals the most of all the treatments, even without the addition of water. Third, chemical control experiments tested a variety of herbicides with different modes of action and at varying rates at two sites. Some herbicides labeled as grass-specific also have activity on Erodium species but do not damage most CSS native forbs and shrubs, and were tested in a variety of concentrations. Chemicals tested in this study did not provide season-long control of Erodium species at rates allowed by the label, but one above-label rate proved effective. Multiple applications of herbicides with this mode of action (e.g., fluazifop) within approved rates should be tested to determine efficacy on Erodium. The broadleaf-selective chemical triclopyr provided the best control but will have to be used with caution in the CSS community as it also has activity on native shrubs and forbs. The broad spectrum herbicide glyphosate had good control at one site, but the second site had germination of a second cohort of Erodium after the first cohort was sprayed.
Author: Emily Griffoul Publisher: ISBN: 9780355414226 Category : Languages : en Pages : 41
Book Description
Significant resources are invested in the restoration of degraded Coastal Sage Scrub in Southern California to meet conservation goals. Thus, understanding the resilience of these systems is of great importance given their high value intersection with human settlements. The presence of invasive annual species has been suggested to add complexity to ecological restoration efforts by inhibiting the growth of native species, changing fire regimes, and altering water balance. To further understand these ideas, I utilized a long-term experiment testing the effectiveness of "passive" restoration, the removal of non-native species without expensive site preparation or resource-intensive active planting / seeding of native species, which means that the approach could be designed to have widespread positive effects at potentially minimal costs. I found that passive restoration was successful at meeting restoration goals of increasing native shrub cover. Two ecological mechanisms---the establishment of new individuals on the landscape versus the expansion of plant size of existing shrubs---were likely responsible for the variation in patterns of recovery for localities with different initial native shrub cover. These patterns give insight into how to affect change in communities through management intervention. Better formulating a conceptual model of the contemporary dynamics of Coastal Sage Scrub informs decisions on expending limited resources to different intensities of restoration across a complex landscape to maximally impact conservation.
Author: Publisher: ISBN: Category : Electronic books Languages : en Pages : 91
Book Description
Nitrogen deposition and precipitation variability can have large effects on the structure and composition of Coastal Sage Scrub communities. These can occur as direct responses to changes in resource availability or indirectly through shifts in the competitive relationships among the many native and non-native plant species. These interactions can influence phenology, limit species distributions, and may play a role in the extinction risk of rare plants. There have been studies on how resources impact invasive species in Coastal Sage Scrub but few have focused on the impacts of invasive grasses on rare, endemic native forbs. I conducted a greenhouse study of the effects of nitrogen and moisture on the relationship between Acanthomintha ilicifolia (a rare native forb) and an invasive grass Brachypodium distachyon. I employed a 3-way factorial design using three moisture levels, three nitrogen treatments, and the application of a selective herbicide used to manage Brachypodium distachyon. Multiple metrics were used to assess the impact of the treatments including aboveground biomass, flower production and timing, leaf size, and chemical composition. For both species, inter and intraspecific competition limited vegetative growth and competitor densities was often more important than the identity of the competitor. We observed weak nitrogen addition effects, likely due to unexpectedly high levels of nitrogen in the natural soil used in the experiment. Total amount of water was not an important factor in this experiment. This could be the result of the relatively mild conditions in the greenhouse or because our experiment could not mimic other stressors like extreme variability in soil moisture and large changes in temperature and insolation. Finally, herbicide treatment was effective at controlling Brachypodium distachyon however significant delays in growth and flowering of Acanthomintha ilicifolia were observed. Herbicide treatment also appeared to alter soil nitrogen relationships. These observed changes in phenology of the endangered species and belowground soil processes need to be considered prior to its continued and wide-spread use in conservation management. Although it can be difficult to extrapolate the results of greenhouse experiments to the field, our results have significant implications for current management practices and warrant further research.
Author: Claire Elizabeth Wainwright Publisher: ISBN: 9781124540108 Category : Languages : en Pages : 31
Book Description
Exotic annual grasses are invading native plant communities in many areas including the western United States, and pose a significant challenge to habitat restoration. Observations in California grasslands suggest that exotic species may become active earlier in the growing season than native species, and that this distinct phenology may contribute to invasion success. We hypothesized that flexible germination cues may allow exotic annual grasses to start annual growth early each growing season and preempt resources prior to native seedling establishment, a kind of seasonal priority effect. Flexible germination cues could incur a cost, however, if they cause seeds to germinate before the onset of favorable growing conditions. To evaluate these predictions, we compared native and exotic species performance in a coastal sage scrub community under both early (off-season) and ambient (natural) rainfall timings. Exotic annual grasses germinated substantially with off-season watering, but none of the early seedlings survived until the onset of the natural rains. Exotic annual grasses that experienced off-season watering had a depleted seedbank and lower germination following the natural rains. In contrast, native species did not germinate following the off-season watering pulse, and instead emerged with the beginning of the cold natural rains. Our results suggest that phenology is an important factor influencing invasion success and invader impact. Under some conditions, pre-growing season watering could be an important restoration strategy for native plant communities in early stages of invasion by depleting the exotic seedbank and allowing for native species to establish with reduced competition.
Author: Wendy Dunbarr Publisher: ISBN: Category : Languages : en Pages : 66
Book Description
Non-native invasive plants threaten native plants in ecosystems through competition for resources, alteration to ecosystem functions and disturbance regimes, and changes to food webs and mutualistic relationships. Decades of intense disturbance and fragmentation of coastal sage scrub in Southern California have led to type conversion from mixed native shrub cover to non-native annual grassland in many places. Restoration efforts have been carried out by various government and private land managers in an effort to preserve existing coastal sage scrub and create additional habitat. Ecological restoration typically focuses on vegetation for both restoration activities and assessments of project outcomes. Additional measures of ecosystem function should be considered when evaluating the progress of restoration projects. Terrestrial arthropods occupy a wide breadth of niches and provide valuable ecosystem services (seed dispersal, x decomposition, food sources for higher trophic levels). They are also sensitive to subtle, small-scale changes in the environment, which makes them more likely to be restored before larger animals. This study compared terrestrial arthropod assemblages along with vegetation characteristics among three types of sites (invaded, restored, native) to evaluate the success of two coastal sage scrub restoration projects within the Santa Monica Mountains National Recreation Area. Terrestrial arthropod assemblage compositions were successfully restored at both canyons. These results agreed with vegetation results at Cheeseboro Canyon, but contradicted vegetation results at Zuma Canyon. The results of this study indicate that restoration projects at both canyons were successful. The successful restoration of arthropod assemblage compositions despite spatial isolation and vegetative differences of the restored areas supported the Field of Dreams hypothesis that “if you build it, they will come”. The addition of terrestrial arthropod data to the standard practice of vegetation monitoring provided a more thorough evaluation of the status of these restoration projects, and should be used by land managers in the future.
Author: Kristin Anne Weathers
Author: Kristin Anne Weathers
Author: Emily Griffoul
Author: Alice Esther Levine
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Author: Marlyce Ann Myers
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Author: Kendall Herbert Osborne
Author: Claire Elizabeth Wainwright
Author: Wendy Dunbarr
Author: Tara Elizabeth Stark