The 178,000-acre Grassland Ecological Area in California’s San Joaquin Valley is managed to provide overwintering habitat to waterfowl on the Pacific Flyway. The major management activity is the fall flooding and spring drawdown of wetlands, timed to optimize the availability of forage vegetation and invertebrates for ducks and shorebirds. Wetland drainage contains salt, boron, and trace elements that are, in part, derived from imported surface water but also concentrate during storage in the wetland impoundments. The spring drawdown drainage contributes to occasional water quality violations in the San Joaquin River (SJR) during dry years. Compliance with water quality objectives may be improved by delaying the traditional wetland drawdown period approximately one month to coincide with high SJR salt assimilative capacity during mid-March to mid- April when reservoir releases are increased to aid salmon migration. However, this delayed drawdown may affect the quality and quantity of wetland vegetative forage, increase wetland soil salinity, and possibly alter the concentrations of algae, invertebrates, and pollutants in the wetlands. In the research presented herein, initial data were collected on the effects of delayed drawdown on algae, invertebrates, and wetland water quality. The experimental sites chosen were three pairs of matched wetland basins (20-100 acres each) that are part of the larger Modified Hydrology Study being conducted in the Grassland Ecological Area. For each pair, one wetland was managed with a traditional March drawdown; while for the second wetland, drawdown was delayed approximately one month to coincide with the period of high SJR assimilative capacity. During the second year of the study, two drainage sites were sampled to characterize drainage flowing to the SJR from an aggregated wetland area. Soil and water column samples were collected during the flooded periods at the inlets, outlets, and along transects within the wetlands. Water quality analyses included total/volatile suspended solids, conductivity, nitrogen (NH4 +, NO2⁻+NO3⁻, organic), phosphorus (total, PO4 3-), organic carbon, alkalinity, turbidity, temperature, and pH. Planktonic and benthic invertebrates were identified and enumerated. Data were collected between February and April in 2007 and again in 2008. Identified phytoplankton were predominantly chlorophytes and diatoms. Zooplankton that feed on phytoplankton were found in abundance and consisted mostly of Cladocera. Benthic invertebrate densities were also measured to help explain the differences in algal concentrations between ponds. Benthic invertebrates were found to be predominantly Chironomidae. Seasonal loads of volatile suspended solids, total dissolved solids, and total organic carbon were estimated at the two aggregate drainage sites and at one delayed drawdown wetland during the 2008 season. For volatile suspended solids, the discharged load was 1500 lbs at the Buttonwillow drainage site, 2500 lbs at the Los Banos 38 drainage site, and upstream of those sites, 770 lbs were discharged from the Mud Slough 4b wetland. For total dissolved solids, the discharged load was 290 tons, 520 tons, and 26 tons, respectively, for the same locations. Of the factors potentially limiting phytoplankton concentrations, invertebrate grazing was likely the most important. Nutrients were not limiting in either the traditional or modified wetlands, as indicated by sufficient N and P content in the algae biomass. Likewise, inorganic C was not limiting, as indicated by pH (most <9.0 pH). Sunlight intensity was not significantly attenuated by water depth or turbidity, and thus light limitation was not indicated.

In southern Africa, disturbance contributes to the heterogeneity of grassland and savanna ecosystems. Fire and grazing act as the primary disturbances in these systems, and interactions between the two are common. As such, an understanding of the relationship between fire and grazing is essential for the conservation of biotic diversity and the production of high-quality forage for game and livestock. Frequent fires followed by concentrated grazing have been shown to facilitate patches of short, palatable grasses ("grazing lawns") within grassland and savanna landscapes. The effects of grazing lawn management on other aspects of biodiversity have received little attention. Forbs (non-graminoid, herbaceous plants) are an important component of grassland ecosystems, but how they respond to disturbance is largely unknown. This study compared changes in forb communities on and off of firebreaks (an extreme example of a grazing lawn) in a high altitude mesic grassland. Native herbivore biomass was significantly higher on firebreaks than in the surrounding lightly grazed matrix and the firebreaks, while more compacted, did not show significant signs of degradation. There were no significant differences in forb abundance or richness between annually burned and intermittently burned plots, and there was no species turnover associated with the annually burned, heavily grazed treatment. Speciesspecific differences in functional traits on annually burned and intermittently burned plots were likely a function of light limitation, as mammalian palatability scores were nominal. Ultimately, ten years of intensive fire and grazing have had minimal impact on forb communities in a high altitude mesic grassland. The results indicate that in this type of Highveld grassland, heavily grazed and annually burned patches are not detrimental to the forb community and clearly enhance habitat diversity for grazers.

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第20428号 / 農博第2213号 / 新制||農||1048(附属図書館) / 学位論文||H29||N5049(農学部図書室) / 京都大学大学院農学研究科森林科学専攻 / (主査)教授 井鷺 裕司, 教授 柴田 昌三, 教授 神﨑 護 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

A research report submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in partial fulfillment of the requirements for the degree of Master of Science in Resource Conservation Biology. Johannesburg, 29 May 2017. / An understanding of animal foraging behaviour is key to proper management strategies that ensure the survival and species persistence within nature reserves. Here the foraging behaviour of ruminant (hartebeest and wildebeest) and non-ruminant (zebra) grazers were observed and compared between two areas with distinctively different vegetation structure, the natural vegetation (NL) and previously cultivated land (PCL), in Telperion and Ezemvelo Nature Reserves (TENR). Natural vegetation was dominated by tall grass of low greenness with patches of short to very short grass, while the PCL was dominated by areas of very short to short grass (grazing lawns) with patches of medium to tall grass. Step rate (SR) and foraging time spent per feeding station (FTFS) were used as indices of foraging behaviour. I also measured the characteristics of the grass sward (grass height and greenness) grazed on by the three species. Both ruminants had high SR and low FTFS. Despite having similar SR and FTFS, ruminants grazed on grass of different height. Hartebeest preferred tall grass with low greenness content (0-10%), while wildebeest preferred short to very short grass and were significantly selective of areas with relative high greenness (11-50%) on PCL, more so than any other species. Compared to ruminant grazers the non-ruminant (zebra) had low SR and high FTFS and like hartebeest they grazed on medium to tall grass of very low greenness content (0 10%). This study did not reveal any difference in feeding behaviour within species between the two study sites. The finding of this study confirms that ruminant and non-ruminant species have different foraging behaviour, and habitat heterogeneity is necessary for the reserve to support different grazing species. Key words: digestive physiology, feeding station, step rate, wildebeest, hartebeest, zebra / GR2018

Anthropogenic change in the Great Plains of North America within the past two centuries has facilitated extensive woody encroachment by eastern redcedar (Juniperus virginiana, hereafter redcedar). Conversion of grassland to redcedar woodland occurs rapidly as a result of the interaction between changing disturbance and land use patterns. In addition, redcedar encroachment causes compositional shifts in grassland floral and faunal assemblages, and may alter abiotic factors such that grassland restoration efforts are limited. The objectives of this study were to: 1) track vegetation and faunal assemblages in grasslands along a gradient of redcedar encroachment, 2) assess the capacity for experimental tree removal to promote re-colonization of grasslands by associated flora and fauna, and 3) examine the influence of scale on spatial relationships between small-mammal abundance and redcedar cover. During the first phase of my study, I examined herbaceous vegetation, woody vegetation, and small-mammal assemblages at grassland sites along a redcedar encroachment gradient in north-central Oklahoma. I noted hump-shaped trends in the capture rate, species diversity, and species evenness of small mammals along the redcedar encroachment gradient. In addition, higher levels of encroachment were associated with compositional shifts from grassland- to woodland-associated small mammals. Characteristics of the small-mammal assemblage along the gradient corresponded to increases in redcedar cover and the frequency of episodic management events within the past two decades. Experimental redcedar removal during the second phase of my study generally increased vegetation and faunal diversity in 2 years following treatment, and treatment sites having the highest pre-treatment levels of redcedar cover exhibited the greatest responses to tree removal. The results of my study suggested that within the time frame I examined, redcedar encroachment had altered the biotic characteristics of this system, but did not facilitate abiotic shifts capable of constraining rapid grassland recovery. Tree removal also appeared to modulate the effects of consecutive drought and flood years on small-mammal diversity during post-treatment. During the third phase of my study, I examined the strength of association between differences in percent redcedar cover and spatial abundance patterns of 4 common small-mammal species. I examined small-mammal abundance at three relatively small spatial scales (38, 154, and 616 m2) to determine how redcedar-mammal associations were stronger with increases in spatial scale. In addition, I determined whether the influence of spatial scale on redcedar-mammal associations varied along a gradient of redcedar encroachment. The strength of redcedar-mammal associations increased with spatial scale, but was strongest at sites having the lowest levels of encroachment. These results corresponded to variation in the spatial distribution of redcedar cover and compositional differences in the small-mammal species assemblage along the encroachment gradient. Studies examining the effects of woody encroachment will extend our understanding of successional processes and ensure that appropriate management is implemented in the conservation of these imperiled grassland ecosystems.

Conversion of natural grasslands for agricultural uses and intensification of agricultural production has been a major cause of natural ecosystem fragmentation and biodiversity loss. Diversifying agricultural landscapes by adding semi-natural grasslands can potentially help couple agricultural production (i.e., providing food, fiber, and energy to a growing human population) with environmental stewardship, enhancing ecosystem health, and increasing biodiversity. To ensure long-term ecological benefits of buffers and to maintain them as suitable habitat for prairie-associated species, periodic disturbance is required to keep buffers in an early-successional grassland plant community. In this dissertation, I fill knowledge gaps about biodiversity of semi-natural grassland buffers within agroecosystems. I investigate influence of prairie-history on buffer forb communities and effects of disking and burning on semi-natural grassland buffer plant and butterfly communities. I also investigate suitability of using butterflies as surrogates of birds and plants on semi-natural grassland buffers. Prairie-history influenced buffer forb communities, and disking increased forb richness and abundance. Disturbance guild butterflies responded positively to disking, most likely due to increased availability of nectar-rich plants. Grassland guild butterflies were not impacted negatively by disking or burning. Responses of plants and butterflies to disking and burning varied between sampling years. Effects of disking in fall 2007 persisted for two growing seasons, but I observed little effects of disking in fall 2008. Butterflies, with the possible exception of Pearl Crescent, were unsuitable as surrogates for birds. In contrast, butterflies, including Pearl Crescent, showed suitable or marginally suitable correlations with plants. Results of my study should help agricultural producers accomplish environmental conservation objectives and provide science-based information for developing and refining USDA practice standards and policy.

This investigation has had for its purpose the determination of first, all members of the Gramineae (Grass) family found in the county; second, the incidence of each species with the various types of soil; third, the grazing value of each species; fourth, the life span of the parent plants; fifth, the present grassland status; and sixth, the potentialities of developing desirable grassland.

Data collected between 1992/93 and 1996/97 from two long-term grazing trials were used to investigate the interaction between grazing animals and veld grass. In the first trial, the impacts of stocking rate and time of stocking in spring on both livestock performance and veld vigour (defined as the ability of a grass plant to regrow after defoliation) and condition were investigated. In the second trial comparisons were made, firstly between the impacts of sheep and cattle grazing, and secondly between various types and frequencies of rest, on veld vigour and condition. Treatments applied in the first trial comprised four stocking rates, namely 7, 10, 13 and 16 sheep ha¯¹ for the duration of the grazing season, and two times of stocking, namely as early as possible after spring burning and three weeks later. Sheep grazed each treatment continuously throughout the growing season. Treatments were applied to alternate blocks in a two-year cycle with each block resting for a year within a grazing cycle. Animal performance (mass gains over the season) was measured to quantify livestock performance. Herbage availability was measured on a species basis at intervals throughout each season using a dry-weight-rank procedure to determine grazing patterns. Residual effects of the grazing treatments on vigour were determined by measuring herbage regrowth on a species basis during the rest season which followed a season of grazing and comparing these measures to a previously ungrazed control treatment. Effects of the grazing treatment on proportional species composition were determined using a nearest plant point technique. Stocking rate had a non-linear effect on livestock performance, with livestock performance on the lightest stocking rate being less than on the two intermediate stocking rates. The mass gains on the heaviest stocking rate were generally the smallest. Delaying the time of stocking in spring resulted in smaller mass gains during the resultant shorter season. The sheep from both the early and late time of stocking groups had similar mean masses at the end of the season. The advantage of stocking early can thus be attributed more to saving the cost of alternative feed for the interim period than to additional mass gains due to stocking early. Quantification of livestock performance in terms of selected and available feed quality, quantity and species availability throughout each season was extremely complex due to multiple thresholds in the measured variables and no simple cause and effect relations could be established that would hold for spatial or temporal extrapolation. The negative impact of grazing on veld vigour was severe. Stocking rate and time of stocking had a secondary impact with the vigour loss positively related to increasing grazing pressure. The main factor influencing vigour loss was grazing, irrespective of time of stocking or stocking rate, as opposed to no grazing. The impact of grazing on vigour was severely negative in the palatable species, variable in the species of intermediate palatability and positive in the unpalatable species that were rarely, if ever, grazed. The stocking rate and time of stocking rate had an impact on the proportional species composition, with the more palatable species declining in proportion. There was an observable relation between impact of grazing on vigour and on species composition. Treatments applied in the second trial involved applying a full growing season rest in alternate years, half a growing season rest (late season) in alternate years and no rest to veld grazed by sheep or cattle at similar stocking rates. Residual effects of the treatments on veld vigour were determined by measuring species regrowth using a dry-weight-rank technique during the season following treatment application, and comparing it to controls ungrazed for one and two seasons respectively. Changes in proportional species composition were determined using a nearest plant point technique. The vigour of veld grazed by sheep declined rapidly relative to veld grazed by cattle. The vigour of palatable species was severely impacted, vigour of intermediate species was variably impacted and vigour of unpalatable species increased dramatically on veld grazed by sheep compared to the control treatments. Similar trends occurred in veld grazed by cattle, but to a lesser degree. Resting was beneficial for vigour recovery in both sheep and cattle treatments but it seems that the grazing treatment between rests has a greater influence on the veld vigour and condition than the rest itself. The veld grazed by sheep remained at a substantially lower productivity level than veld grazed by cattle. This was particularly evident in the change in productivity balance between palatable and unpalatable species in the sheep treatments, where palatable species vigour declined and unpalatable species vigour increased relative to veld grazing by cattle. Species composition of veld grazed by sheep deteriorated over the trial period in contrast to the veld grazed by cattle, which improved in species composition. Grazing management recommendations for sourveld should include a bias towards cattle, optimising stocking rate for improved performance and resting for enhancing vigour of the palatable grasses. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1999.

One of the major challenges for agriculture today is to manage soil properties and their spatial distribution to optimize productivity and minimize environmental impacts, such as diffuse pollution. To identify best management practices, the effects of different agricultural management practices on pollutant sources, mobilization, transfer and delivery to water bodies need to be understood. Grasslands managed for dairy and meat production, despite being widespread, have received less research attention than other agricultural land uses. Therefore, this thesis studies the effects of different grassland management practices on soil properties and their spatial distribution and the mobilization and delivery of multiple diffuse pollutants. As a grassland case study, monitoring for this thesis was conducted across three fields (6.5 – 7.5 ha) on the North Wyke Farm Platform, a grassland experimental farm in the UK. First, the effects of permanent grassland management (permanent for at least 6 years, but different grassland management > 6 years ago) were characterized as a baseline, followed by quantifying the short-term effects of ploughing and reseeding of permanent grassland fields. Throughout those management periods, i) a range of soil physical (bulk density [BD]) and chemical (soil organic matter [SOM], total N [TN], total phosphorus [TP], total carbon [TC]) soil properties and their spatial distribution were sampled and analysed by geostatistics, and ii) hydrological characteristics and multiple pollutant fluxes (suspended sediment [SS] and the macronutrients: total oxidized nitrogen-N [TONN], total phosphorus [TP], and total carbon [TC]) were monitored at high temporal resolution (monitoring up to every 15 minutes). The permanent grassland fields (or areas within fields) can be considered to be functioning differently. Past management legacy (more than 6 years ago) has affected soil properties and their distribution with subsequent effects on sediment and macronutrient delivery from the fields to surface waters. Overall, permanent grasslands were found to contribute significantly to agricultural diffuse pollution. The estimated erosion and macronutrient losses were similar to or exceeded the losses reported for other grasslands, mixed land use and even arable sites, and sediment and TP concentrations exceeded those recommended by EU / UK water quality guidelines. Ploughing and reseeding did not homogenize spatial variation and did not override past management effects. Long-term management differences affected soil properties and altered soil processes, so that the fields subsequently responded differently to ploughing and reseeding. All nutrient concentrations were significantly reduced in the older grassland field (no ploughing for 20 years), but not in the younger grassland field (no ploughing for 6 years). Ploughing and reseeding significantly accelerated the losses of sediment and macronutrients and sediment, TP and TONN exceedance frequencies of EU / UK water quality guidelines increased. Additionally, ploughing and reseeding caused a shift in the relative importance of nutrients, by increasing the relative importance of N. Such large sediment and nutrient losses from intensively managed grasslands should be acknowledged in land management guidelines and advice for future compliance with surface water quality standards. The between-field and within-field variation highlights the importance of baseline characterization and paired catchment studies. The long-term effects of management still acting on soil properties and subsequently water quality indicates how long it may take to see soil and water quality improvements after implementing mitigation measures. Therefore, long-term management history always has to be included when interpreting soil and water quality data.

The origin and classification of open and mosaic ecosystems, particularly in the tropics and subtropics, have led to controversy worldwide. This has affected biodiversity conservation and, in some cases, promoted the establishment of afforestation projects based on the assumption that open and mosaic ecosystems are degraded forests. Although this initiative can have benefits in terms of carbon storage and climate mitigation if carefully planned and managed, it can also cause biodiversity loss and degradation when afforestation takes place in areas that were previously open ecosystems, or where unsuitable species are used. Madagascar, a world biodiversity hotspot, is one of the countries targeted for the implementation of afforestation projects. The Central Highlands of Madagascar, dominated by grassland matrix with forest patches, is the main region targeted. The nature and origin of the landscape are hotly debated, however, and it is not clear whether these open ecosystems are ancient or anthropogenically derived. Understanding of landscape history is therefore required to identify and conserve ancient open ecosystems, and to distinguish them from areas that have been deforested by people. This research aims to reconstruct the vegetation history and environmental change in the Central Highlands of Madagascar during the Holocene using palaeoecological methods, in order to inform appropriate conservation and management plans. We provide new records of vegetation, hydrological change, fire and herbivory activities by using a multiproxy approach, which includes fossil pollen, stable carbon isotopes, diatoms, charcoal and coprophilous spores, that allows for a comprehensive investigation into the history and drivers of vegetation change. Sediment cores were collected from two sites, Tampoketsa-Ankazobe wetland and Lake Dangovavy, located in the eastern and western slopes of the highlands, respectively. Results indicated that the surrounding area of both sites was composed of mosaic ecosystems, comprising of forest patches of variable extent in a matrix of open grassland and ericoid shrubland vegetation, at least from the Early and Mid-Holocene to ca. 1000 cal years BP, driven mainly by climate variability and fire occurrence. In Tampoketsa-Ankazobe wetland (eastern slopes), the vegetation was characterised by a mosaic of ericoid shrubland and mid-elevation forest taxa, between ca. 11 200 and 8300 cal years BP, under warm/wet period and low fire occurrence. The vegetation in the area changed to a mosaic of ericoid shrubland with more dominance of high-elevation forest from ca. 8300 to 1000 cal years BP under a drier climate and consistent low fire occurrence. The abundance of shrubs and trees during those two periods were confirmed by the dominance of C3 plants as reflected by the stable carbon isotopes results, and coincided with low herbivory activities in the TampoketsaAnkazobe site from ca. 11 200 to 1000 cal years BP. In parallel, the pollen record from Lake Dangovavy (western slopes), between ca. 6200 and 5400 cal years BP, suggests a mosaic ecosystem, dominated by more C3 montane grass, ericoid shrubland and high elevation forest patches promoted by cool/dry climate with low fire occurrence and herbivory activities. Between ca. 5400 and 4200 cal years BP, vegetation in the area was dominated by a mosaic of ericoid shrubland and mid-elevation forest under a wetter period, moderate fire occurrence, and herbivory activities. This mosaic was controlled by climate, fire refugia and herbivory feedbacks. The vegetation changed into a forest-savanna mosaic with an abundance of grassland and pioneer/fire-resistant trees between ca. 4200 and 3000 cal years BP. The period was characterised by an initial increase of local fire followed by a regional drought event. This suggests that a threshold might have been reached, with a resulting shift in vegetation composition. Between ca. 3000 and 1000 cal years BP, reoccurrence of ericoid shrubland with woodland savanna taxa was recorded in the area. The vegetation was conditioned by variation of climate from wet (until ca. 2000 cal years BP) to dry period (ca. 2000–⁠1000 cal years BP) with moderate fire occurrence and herbivory activities. In addition, stable carbon isotope results show that between ca. 6200 to 1000 cal years BP, the site was characterised by C3 plants. During the last ca.1000 cal years BP, pollen records from both sites in the Central Highlands of Madagascar showed a shift to a more open landscape dominated by grassland. Trees and shrubland in the highlands experienced a massive decrease and this correlated with an abundance of C4 plants associated with reduced diversity. The shift of vegetation during this period was likely a result of a centennial severe drought period at ca. 950 cal years BP, as recorded in the literature and confirmed by the peak in aerophilous taxa in our diatom record. The drought was followed by a dramatic increase of fire occurrence and herbivory activities in the region, as recorded in the charcoal and spore records from both sites, indicating human activities at ca. 700 and 500 cal years BP for Lake Dangovavy and Tampoketsa-Ankazobe wetland, respectively. Though the vegetation at both sites in Central Highlands of Madagascar was very dynamic until ca. 1000 cal years BP, complex interactions between climate and fire allowed the forest and ericoid elements to persist, consistent with a heterogeneous mosaic landscape. This changed from 1000 years ago with the occurrence of a regional severe drought event followed by an increase in human activities leading to an increase of grass, a decline in forest and ericoid elements. Our findings suggest that although, the eastern and western slopes in Madagascar might have different vegetation histories over time as a response to the complex climatic-fire drivers at least until ca. 1000 cal years BP, they both: a) Contained ancient open ecosystems such as grasslands and/or ericoid shrubland, and a mosaic landscape which should be considered typical of the highland region. b) Experienced a loss of forest, woodland and mosaic elements, a trend that is consistent with the anthropogenic conversion of some forests to grasslands since ca. 1000 cal years BP. Such findings have implications in terms of conservation, fire management and afforestation projects in the Central Highlands, and provide additional knowledge that contributes to the understanding of its ecological processes and history prior to human arrival on the island. Indeed: 1) Ancient grasslands and ericoid shrubland need to be identified and conserved because of their antiquity and unique biodiversity. To date, there has been some focus on ancient grasslands, but the presence of ancient heathlands has not been discussed. 2) It is important to distinguish ancient from derived grasslands and to target the latter for reforestation, using species that are typical of the remaining forest patches. 3) Fire management should be conducted at a local scale and should incorporate the landscape fire history, considering, for example, the differences between two slopes in the Central Highlands.