Fencing Treatments Research Articles

Management of re‐established artificial grasslands via grazing or fencing: Effects on plant and soil properties

AbstractBackgroundRevegetation is widely used in degraded grassland restoration. However, the responses of grassland plant and soil properties to fencing (FC) and grazing (GZ) remain poorly understood, especially the vegetation–soil coupling coordination (Cd) mechanism. This study explored single and interactive responses of vegetation and soil properties under FC and GZ after revegetation.MethodsA field experiment with FC and GZ treatments was conducted in Loess Plateau reconstructed grassland, with degraded grassland as the control (CK). Plant and soil properties and Cd were analyzed using the analytic hierarchy process (AHP) and principal component analysis (PCA).ResultsThe order of soil comprehensive evaluation (SCE) was GZ > FC > CK, while that of vegetation comprehensive evaluation (VCE) was FC > GZ > CK. The Cd of CK was 0.39 (mild imbalance), while the values of FC and GZ were 0.57 and 0.54, respectively (little coordination). The VCE/SCE of FC was 1.48 (soil lag type), and the values of GZ and CK were 0.69 and 0.35, respectively (vegetation lag and vegetation loss type, respectively).ConclusionsBoth GZ and FC improved Cd and facilitated recovery. However, degraded grasslands should be restored via moderate grazing for sustainable ecological and economic development.

Successful restoration of Metrosideros polymorpha (ʻōhiʻa) is possible in forest sites with active Rapid ʻŌhiʻa Death infections

Rapid ʻŌhiʻa Death (ROD), caused by the fungal pathogen Ceratocystis, is killing large numbers of ʻōhiʻa trees (Metrosideros polymorpha) in Hawaiʻi. ʻŌhiʻa are a dominant tree in Hawaiian forests, have a range that goes from arid to wet forest climates, and are important for endangered species habitat and ecosystem function. To test whether actively planting ʻōhiʻa seedlings is a viable restoration strategy in areas with high ROD mortality, we planted ʻōhiʻa in a ROD‐affected forest and crossed this with weeding and fencing treatments to compare ROD mortality to other stressors. We also tested for viable Ceratocystis spores in soils around planting areas. We found that seedlings were more likely to die in unweeded and unfenced treatments than controls. Although viable Ceratocystis spores were found in soil, none of the 41 dead seedlings tested positive for Ceratocystis. This indicates that competition from exotic plants and exotic feral ungulate damage are more likely to kill seedlings than ROD within the first year after planting.

Establishment success and persistence of threatened plant translocations in south west Western Australia: an experimental approach

Establishment of viable threatened plant populations through translocations presents significant practical and logistical challenges. To address these challenges there is a need for experimental studies that inform refinement of translocation methodologies to optimise seedling survival during the establishment phase. In the present study we investigated the effect of three post planting techniques on the survival and growth of six translocated threatened plant species in south-west Western Australia over a 10-year period. Planted seedlings received summer watering for the first year, mulch or protection from vertebrate herbivores. Survival of seedlings was significantly enhanced in both watering and fencing treatments, but was not positively influenced by the mulch treatment. Plant growth was also significantly improved by the fencing treatment. Results showed that both fencing and supplementary summer watering were two very effective approaches for enhancing seedling establishment and plant persistence. We emphasise the value of integrating an experimental approach involving long-term monitoring into threatened plant species translocations and recovery programs for improving plant translocation success.

Effects of fencing and grazing on the temporal dynamic of soil organic carbon content in two temperate grasslands in Inner Mongolia, China

This study aimed to investigate the impact of long-term grassland management on the temporal dynamic of SOC density in two temperate grasslands. The top soil SOC density, soil total nitrogen density and soil bulk density (0–20 cm) under long-term fencing and grazing treatments, the aboveground net primary productivity of fenced plots and the associated climatic factors of Leymus chinensis and Stipa grandis grasslands in Inner Mongolia were collected from literatures and analyzed. The results showed that the SOC density increased linearly with fenced duration but was insensitive to grazed duration in both grasslands. Compared with long-term grazing, fenced plots had larger potential for carbon sequestration, and the accumulation rate of SOC density was 29 and 35 g Cm–2y–1 for L. chinensis and S. grandis grasslands. Fenced duration and mean annual temperature jointly contributed large effect on temporal pattern of SOC density. Climate change and grazed duration had little influence on the inter-annual variance of SOC density in grazed plots. Our results confirmed the enhancement effect of long-term fencing on soil carbon sequestration in degraded temperate grassland, and long-term permanent plot observation is essential and effective for accurately and comprehensively understanding the temporal dynamic of SOC storage.

Long-term ungulate exclusion reduces fungal symbiont prevalence in native grasslands.

When symbionts are inherited by offspring, they can have substantial ecological and evolutionary consequences because they occur in all host life stages. Although natural frequencies of inherited symbionts are commonly <100%, few studies investigate the ecological drivers of variation in symbiont prevalence. In plants, inherited fungal endophytes can improve resistance to herbivory, growth under drought, and competitive ability. We evaluated whether native ungulate herbivory increased the prevalence of a fungal endophyte in the common, native bunchgrass, Festuca campestris (rough fescue, Poaceae). We used large-scale (1ha) and long-term (7-10year) fencing treatments to exclude native ungulates and recorded shifts in endophyte prevalence at the scale of plant populations and for individual plants. We characterized the fungal endophyte in F. campestris, Epichloë species FcaTG-1 (F. campestris taxonomic group1) for the first time. Under ungulate exclusion, endophyte prevalence was 19% lower in plant populations, 25% lower within plant individuals, and 39% lower in offspring (seeds) than in ungulate-exposed controls. Population-level endophyte frequencies were also negatively correlated with soil moisture across geographic sites. Observations of high within-plant variability in symbiont prevalence are novel for the Epichloë species, and contribute to a small, but growing, literature that documents phenotypic plasticity in plant-endophyte symbiota. Altogether, we show that native ungulates can be an important driver of symbiont prevalence in native plant populations, even in the absence of evidence for direct mechanisms of mammal deterrence. Understanding the ecological controls on symbiont prevalence could help to predict future shifts in grasslands that are dominated by Epichloë host plants.

Determining the Effects of Cattle Grazing Treatments on Yosemite Toads (Anaxyrus [=Bufo] canorus) in Montane Meadows

Amphibians are experiencing a precipitous global decline, and population stability on public lands with multiple uses is a key concern for managers. In the Sierra Nevada Mountains (California, USA), managers have specifically identified livestock grazing as an activity that may negatively affect Yosemite toads due to the potential overlap of grazing with toad habitat. Grazing exclusion from Yosemite toad breeding and rearing areas and/or entire meadows have been proposed as possible management actions to alleviate the possible impact of cattle on this species. The primary objective of this study was to determine if different fencing treatments affect Yosemite toad populations. We specifically examined the effect of three fencing treatments on Yosemite toad breeding pool occupancy, tadpoles, and young of the year (YOY). Our hypothesis was that over the course of treatment implementation (2006 through 2010), Yosemite toad breeding pool occupancy and early life stage densities would increase within two fencing treatments relative to actively grazed meadows due to beneficial changes to habitat quality in the absence of grazing. Our results did not support our hypothesis, and showed no benefit to Yosemite toad presence or early life stages in fenced or partially fenced meadows compared to standard USDA Forest Service grazing levels. We found substantial Yosemite toad variation by both meadow and year. This variation was influenced by meadow wetness, with water table depth significant in both the tadpole and YOY models.

Life‐history constraints in grassland plant species: a growth‐defence trade‐off is the norm

Plant growth can be limited by resource acquisition and defence against consumers, leading to contrasting trade-off possibilities. The competition-defence hypothesis posits a trade-off between competitive ability and defence against enemies (e.g. herbivores and pathogens). The growth-defence hypothesis suggests that strong competitors for nutrients are also defended against enemies, at a cost to growth rate. We tested these hypotheses using observations of 706 plant populations of over 500 species before and following identical fertilisation and fencing treatments at 39 grassland sites worldwide. Strong positive covariance in species responses to both treatments provided support for a growth-defence trade-off: populations that increased with the removal of nutrient limitation (poor competitors) also increased following removal of consumers. This result held globally across 4 years within plant life-history groups and within the majority of individual sites. Thus, a growth-defence trade-off appears to be the norm, and mechanisms maintaining grassland biodiversity may operate within this constraint.

三种利用方式对羊草草原土壤氨氧化细菌群落结构的影响

以内蒙古呼伦贝尔羊草草原为研究对象,利用聚合酶链式反应-变性梯度凝胶电泳(PCR-DGGE)技术及扩增产物序列分析方法比较研究了刈割、放牧和围栏封育3种利用方式对羊草草原土壤氨氧化细菌多样性和系统发育的影响,结果表明:羊草草原土壤中氨氧化细菌的优势类群为亚硝化螺旋菌属和亚硝化单孢菌属的细菌,分别占氨氧化细菌总数的72.4%和28.6%,Cluster 4和Cluster 6在各个样地中均为优势类群但所占比例不同,放牧样地中氨氧化细菌的多样性最高,逐步回归分析的结果表明,影响多样性指数的关键理化因子是土壤硝态氮含量。放牧样地中脲酶活性和硝化率都显著高于其他两种利用方式,其中,脲酶活性与土壤硝态氮和全磷含量表现出极显著的相关性,与速效磷含量表现出显著相关性;而硝化率仅与硝态氮含量表现出显著相关性。不同利用方式土壤氨氧化细菌群落与土壤理化因子的典范对应分析结果表明铵态氮的含量对氨氧化细菌群落的影响显著。;Available nitrogen is not only one of the most important limitation resources to manipulate primary productivity, but also a major factor to decide species composition in a grassland ecosystem. Chemolithotrophic nitrification is a two-step process, consisting of the conversion of ammonia to nitrite then further to nitrate. Those steps are involved two different groups of organisms, the ammonia-oxidizing bacteria (AOB) and the nitrite-oxidizing bacteria (NOB), respectively. In this study, the active AOB community was investigated by using approaches of polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and sequences analysis on the <em>Leymus chinensis</em> steppes with three of mowing, grazing and fencing treatments respectively in Hulunbeier steppe of Inner Mongolia. Sampling in August 2008 when vegetation was at its best condition. Samples were taken at depths of 0-0.20m. The community structure and diversity of the bacterial groups from the different samples was further analyzed by using different techniques, such as statistical analysis and diversity index evaluation of the band patterns etc. The results showed that grazing activity significantly increased the number of species and quantities of AOB, as well as the diversity. A total of 21 sequences representing 21 different sequence types were recovered from the DGGE gels after phylogenetic reconstructions. The results further revealed that most sequences were coming from <em>Nitrosospira</em> and <em>Nitrosomonas</em> of <em>β</em>-<em>Proteobacteria</em>, with accounting for 72.4% and 28.6% respectively. Cluster 4 of <em>Nitrosospira</em> existed in grazing, mowing and fencing plots with accounting for 25.0%, 27.2% and 26.3% respectively in their dominant AOB. And Cluster 6 of <em>Nitrosomonas</em> existed in grazing, mowing and fencing plots, those accounted for 33.1%, 18.1% and 21.1% respectively in their dominant AOB. Analyze of stepwise regression showed that the key soil physicochemical factor which influence the diversity index most is the content of nitrate nitrogen. Urease activity and nitrate rate in grazing plot were both higher than the other land use patterns. The content of nitrate nitrogen and total phosphorus were both extremely significant (<em>P</em><0.01) correlated with urease activity, and there is a significant (<em>P</em><0.05) relationship between urease activity and the content of available phosphorus; at the same time, there is also a significant relationship between nitrate rate and nitrate nitrogen contents. AOB communities in <em>Leymus chinensis</em> steppe were significantly (<em>P</em><0.05) influenced by the levels of ammonium nitrogen when canonical correspondence analysis was employed to identify relationship between AOB and soil physicochemical factors under different land use patterns. Based on the above findings, it seems that nitrogen cycles represent the key links between above and below ground ecosystems. Land use patterns in<em> Leymus chinensis</em> steppe have significant and long-term impacts on the size and the structure of the soil AOB community at both phylogenetic and functional levels, thus would further affect the transformation and utilization of nitrogen in the steppe ecosystem.

Cattle Grazing and Yosemite Toad (Bufo canorus Camp) Breeding Habitat in Sierra Nevada Meadows

Abstract Exclusion of cattle by fencing has been proposed to alleviate possible negative grazing impacts on hydrologic, water quality, and cover habitat conditions within Sierra Nevada meadows used by Yosemite toads ( Bufo canorus Camp) for breeding. Our objectives were to: 1) determine associations between breeding pool habitat conditions and use of potential breeding pools by toads; and 2) determine how habitat conditions respond to cattle exclusion treatments on the Sierra National Forest, California. We randomly selected two toad occupied and two unoccupied breeding pools in each of nine meadows for this study ( n = 36 breeding pools). After baseline data collection in 2006, three meadow fencing treatments were implemented over the course of 3 yr. Treatments were fencing to exclude cattle from the entire meadow; fencing to exclude cattle from toad breeding and rearing areas, with grazing allowed in the remaining unfenced portion of the meadow; and cattle grazing allowed across entire meadow. We monitored hydrologic, water quality, and cover habitat variables as well as toad occupancy during the breeding seasons of 2006 through 2008. Concentrations of water quality constituents were uniformly low all years regardless of treatment. Occupied pools were shallower, warmer, and more nitrogen enriched than unoccupied breeding pools. We found no evidence of improved toad breeding pool habitat conditions following fencing compared to standard US Forest Service grazing management.

The Effects of Fertilization and Herbivory on the Phenology of the Understory Vegetation of the Boreal Forest in Northwestern Canada

Environmental conditions associated with climate change, such as earlier snowmelt, warmer spring temperatures, and increased soil mineralization, have resulted in shifts in the timing of plant phenological events. We assessed the effects of fertilizer and herbivory on the phenology of 7 plant species from a boreal forest understory using long-term experimental plots in the southwest Yukon. Fertilizer and fencing treatments were initiated in 1990, and discontinued in half of each plot in 2000. There were few effects on phenology of either fertilizer or fencing. In some species, fertilizer affected the final phenological stage reached, but the presence and direction of the effect was species-dependent. Epilobium angustifolium was the only species where the timing of phenological stages responded to fertilization; early phenological stages were advanced with fertilizer. First leaf expansion for Arctostaphylos uva-ursi occurred earlier in fenced plots, although this effect disappeared in plots where the fencing treatment had been discontinued. We conclude that previously observed changes in species abundance with fertilizer treatments are likely not caused by changes in the phenology of these species, and are more likely due to fertilization imposed changes in vegetative growth.

Using Digital Photography to Examine Grazing in Montane Meadows

Abstract Cattle ( Bos taurus ) numbers on national forests are allocated based on allotment grazing capacity, but spatial patterns of timing and density at smaller scales are difficult to assess. However, it is often in meadows or riparian areas that grazing may affect hydrology, biodiversity, and other important ecosystem characteristics. To explore real-time animal presence in montane meadows we distributed 18 digital cameras across nine sites in the Sierra National Forest, California. Our objectives were to document seasonal and diurnal presence of both cattle and mule deer ( Odocoileus hemionus ), identify the effects of three fencing treatments on animal distribution, and test digital photography as a tool for documenting cattle presence. We recorded 409 399 images during daylight hours for two grazing seasons, and we identified 5 084 and 24 482 cattle “marks” (instances of animal occurrence) in 2006 and 2007, respectively. Deer presence was much lower, with 331 marks in 2006 and 598 in 2007. Morning cattle presence was highest before 0800 hours both years (13.7% and 15.4% of total marks for 2006 and 2007, respectively). Marks decreased until 1100 hours and then increased around 1400 hours and remained relatively stable until 1900 hours. Marks then rose precipitously, with > 20% of total marks recorded after 1900 hours both years. Deer presence was less than 10% per hour until 1800 hours, when > 20% of total marks were recorded after this time both years. Among treatments, cattle marks were highest outside fences at partially fenced meadows, and deer were highest within completely fenced meadows. Our experience suggests that cameras are not viable tools for meadow monitoring due to variation captured within meadows and the time and effort involved in image processing and review.

Influence of grazing and vegetation type on post-fire flammability

1. Natural area managers use fire and grazing to achieve nature conservation/production goals and to prevent the loss of life and property. Yet, little is known of the effects of post-fire grazing on fuel load and the proportion of days on which fire can be sustained (fire potential). This knowledge could help managers in planning interventions to achieve their goals. 2. At seven sites in Tasmania, Australia, including sedgeland, heathy forest and grassland, fire potential and fuel load were measured before, and for 2 years after fire. Measurements were made in burning, fencing and burning plus fencing treatments, and in control quadrats. 3. Burning followed by grazing, largely by native vertebrates, resulted in lower fuel loads than either grazing by itself or burning by itself. A new steady state was established in two grasslands. Fire potential at the oligotrophic sites was largely a function of time elapsed since the last fire, while at grassy sites was increased by grazing without fire, but depressed or slightly increased by grazing after burning. 4. Synthesis and applications. Effects of grazing after burning on flammability are not predictable from the single or additive effects of grazing and burning, varying between vegetation type and environment. In highland grassy ecosystems fire potential can be reduced by excluding grazing animals after fire, while in scleromorphic ecosystems grazing after fire does not affect fuel or fire potential. Intense grazing after fire can cause an, often desirable, shift from tussock to lawn grassland. Burning and subsequent grazing of tussock grassland vegetation in the lowlands may reduce the chance of wildfire damaging property and conservation/production values, while in highland tussock grassland burning followed by grazing will be largely ineffective in reducing the already low chance of such damaging fire.

Amur Honeysuckle (Lonicera maackii) Management Method Impacts Restoration of Understory Plants in the Presence of White-Tailed Deer (Odocoileus virginiana)

AbstractManagement methods for invasive species vary in their restoration success in the presence or absence of herbivores. We investigated the performance of understory plants after management of the invasive shrub Amur honeysuckle using two herbicide-based methods (cut/paint and basal application) in fenced and unfenced plots. The cut/paint method resulted in the removal of above-ground stems, while the basal application method resulted in the dead stems remaining in place. Light level in the cut/paint treatment was higher than in the basal application treatment, which was higher than in the control (no management) treatment. Across fencing treatments, fruit production, height, and subsequent recruitment of transplanted jewelweed were greater in the cut/paint treatment. Across management treatments, jewelweed plants were taller in the fenced treatment. Native species richness was generally higher in the cut/paint and basal application treatments than in the control treatment. There were more jewelweed recruits, more jewelweed fruits, and greater native species richness in the cut/paint treatment than in the basal application treatment in fenced plots, but these measures were similar in both management treatments in unfenced plots. Thus standing dead stems of Amur honeysuckle offered protection from damage in the presence of herbivores, offsetting the advantage of the cut/paint method seen in the fenced plots. There was a trend for more leaves of transplanted wild ginger in the basal application treatment. There were more invasive garlic mustard and more Amur honeysuckle seedlings in the cut/paint treatment than in the control treatment. Our results illustrate the complexities involved in selecting appropriate restoration management techniques given herbivore pressure, differential species response, and presence of multiple invasive species. In our study, we demonstrated that the basal application honeysuckle management method (and therefore perhaps similar methods that leave the dead stems standing) led to increased understory plant restoration success when compared to the cut/paint method.

REFINING SAMPLING PROTOCOLS FOR INVENTORYING INVERTEBRATE BIODIVERSITY: INFLUENCE OF DRIFT-FENCE LENGTH AND PITFALL TRAP DIAMETER ON SPIDERS

Abstract The limited resources available to inventory biodiversity and conduct ecological monitoring requires efficient protocols for sampling with pitfall traps. Here we consider adding different length drift-fences to pitfall traps on spiders. Four different fencing treatments (no fence, or fence lengths of 2, 4 and 6 m) were evaluated in combination with three trap diameters (4.3, 7.0 and 11.1 cm). Three-way ANOVAs revealed no significant interaction effects between any combinations of fencing treatments, trap size or the spatial positioning of transects within the study site along which traps were arranged. Post-hoc tests showed fences significantly increased the abundance of individuals and richness of spider families, and species collected. Traps with 6 m fences were significantly higher in all of these variables than traps with 2 m fences. ANOSIMs revealed taxonomic composition differed significantly between fenced and unfenced traps at familial, and specific ranks. Among fenced traps, taxonomic co...

Survival, growth, and escape from herbivory are determined by habitat and herbivore species for three Australian woodland plants.

To understand how plant communities are structured by herbivory it is essential to investigate the roles of different herbivores and the responses of a variety of plant species in different habitats. We examined the effects of mammalian herbivores on survival and growth of transplanted seedlings of two native trees (Eucalyptus albensand Callitris glaucophylla), and one native grass (Themeda australis) in white box ( E. albens) woodlands in eastern Australia over 3 years. Herbivores were manipulated using four fencing treatments that successively excluded livestock, macropods, and rabbits from woodland and grassland (cleared pasture). Survival was highest in the absence of mammalian herbivores and in woodlands, and patterns differed among plant species. Survival of T. australis was low, especially in grasslands, and mortality by overgrowth was common in ungrazed treatments. All plant species were taller in fenced plots, and differences between treatments were greater in grassland. Rabbits and livestock had the greatest influence on C. glaucophylla, while T. australis and E. albens were most affected by livestock and macropods. We used field data to parameterize stage-classified matrix models to predict escape from herbivory (escape height >100 cm) for tree species. Reduced herbivory increased the proportion of individuals reaching escape height after 15 years. Rate of escape was greater in grassland, and this faster growth appeared to counteract much of the negative impact of herbivores. While T. australis was unable to escape herbivory, larger, ungrazed individuals were more likely to flower and therefore contribute to the maintenance of the population. Our results show that habitat and herbivore species strongly influence the effect of herbivory on vegetation.

The effects of management regime and host species on Sandalwood (Santalum spicatum) recruitment near Paynes Find Western Australia.

Natural recruitment of sandalwood (Santalum spicatum) is generally low in pastoral regions of the Midwest and Goldfields, Western Australia. Harvesting of S, spicatum for the aromatic timber occurs in these regions, creating a need to develop management strategies to conserve the species. This paper examines sandalwood recruitment over three years within a natural stand of 32 ha, near Paynes Find, Western Australia. Santalum spzcatum recruitment success was compared between three establishment treatments, and between two fencing treatments (+I-). At age three years, mean survival of S. spicatum seedlings planted next to host trees (25%) was significantly higher than those planted at harvesting spots (2%) and beneath parent trees (0%). In the unfenced treatment, there was evidence of grazing and S, spicatum survival and growth were significantly lower than in the fenced treatment. However, fencing alone did not improve S. spicatum recruitment because natural seed dispersal was poor and survival beneath parent trees was low. De-stocking, combined with seed enriching host trees is recommended to dramatically improve S, spicatum recruitment in the Paynes Find region. Santalum spicatum seedling performance was compared growing next to three N2-fixing species (Acacia burkittii, A. tetragonophylla and A. ramulosa) and one non N2-fixing species (Hakea recurva). At age three years, S. spicatum survival was significantly higher next to A. burkittii (33%) than A. tetragonophylla (1 7%). Santalum spicatum survival next to A. ramulosa and H. recurva was 24-26%. Fencing improved S. spicatum survival next to A. burkittii, and to a lesser extent next to A. tetragonophylla and A. ramulosa. In contrast, survival of S, spicatum seedlings next to H. recurva was unaffected by fencing. Santalum spicatum growth next to each host species was slow and significantly higher in the fencing treatment. Foliar concentrations of N, P, K and Ca were the same across 5'. spicatum treatments, but the concentration of Mg varied. The foliar K:Ca ratio was also similar between S. spicatum treatments, ranging from 1.4 to 2.0. Key words: Santalum spicatum, recruitment, seed enrichment, host species, foliar nutrients