Secondary Grasslands Research Articles

An in situ study of Magnolia dealbata Zucc. in Veracruz State: an endangered endemic tree of Mexico

Received 4 July 1995; revised and accepted 21 November 1995Magnolia dealbata Zucc. is an endangered species as a result of habitat destruction. A population incentral Veracruz was studied to determine in which of two disturbed habitats (secondary successionforest and grassland) where M. dealbata grows the tree showed better survival. Its spatial dis-tribution was recorded from the two habitats. Density and productivity were recorded over a periodof 1 year, and spatial distribution was found to be non-random at p <0.001 for both habitats. Thescales of pattern detected were inferred to be caused by gravity-dispersed seeds germinating close tothe mother trees. A higher number of individuals, with higher flower and fruit production, wasrecorded in the secondary succession forest habitat, and it appears that M. dealbata has alsoadapted, but to a lesser extent, to pasture-land habitats. Overall natural regeneration from seed isconsidered low, and its long-term survival could be assured in the secondary succession habitatproviding clear cutting is not practiced.Keywords: conservation; endangered species; Magnolia dealbata; population study; cloud-forest.

The conservation ecology ofIris rossii Baker (Iridaceae), a threatened plant in rural Japan

Spatial distribution, size structure and reproductive activities of a population ofIris rossii were examined in managed secondary grassland with scattered pines and hardwoods. Size structure and fecundity patterns among individuals were different between the three sites, which were an open area, under pine canopy, and under hardwood canopy. Growth and reproductive parameters of the species were significantly different at each site. In the open area, mean shoot number of individuals was 9.17, and it was 6.37 under the pine canopy and 5.63 under the hardwood canopy. Fruit set ratio was 26.8% in the open area, 21.1% under the pine canopy and 12.1% under the hardwood canopy. Six seedlings were found in the open area and one under the pine canopy, while no seedlings occurred under hardwood canopy. Most of the individuals distributed in the sites where the height of herbaceous layer was low. These results suggest thatI. rossii can not grow in the closed, especially hardwood, canopies or tall herbaceous layer. Therefore, human interventions such as annual mowing for the restriction of the growth of dominant grasses and tree saplings are essential for the persistence of the population of the species.

Stocks of Nitrogen in Vegetation and Soil in West African Moist Savannas and Potential Effects of Climate Change and Land Use on These Stocks

Moist savannas which include undifferentiated moist woodlands and savannas with abundant Isoberlinia dokal and L tomentosa (also known as Sudanian woodlands and Guinea-Congolian secondary grassland and wooded grassland) extend across West Africa up to the Central African Republic. Nitrogen stocks in the standing woody vegetation, litter and soil as well as the amounts of nitrogen transferred between these stocks and that lost through savanna burning of woodland and open moist savanna types are presented. Most of the total nitrogen is in the soil and then in the woody vegetation, with the least amount in the herbaceous vegetation.

Human impacts on pine-dominated vegetation in rural landscapes in Korea and western Japan

To understand the human influence on the successional process of vegetation, structures of the pine forest as a dominant vegetation were compared between in Yanghwa-ri of rural Korea and Miwa-cho of rural Japan. The secondary pine forests are well developed around the villages in both regions. In rural Korea, pine forests are still used intensively for several traditional purposes. The pine forests in Yanghwa-ri of Korea, therefore, are stayed in the early stage of the succession. The floristic composition in pine forests of Yanghwa-ri was similar to that in the secondary grasslands. The fertilizer trees such as Robinia and Alnus contributed to develop the stratification of the forest. On the other hand, in Japan, almost all pine forests in rural regions had been abandoned due to the changing of traditional use because of the economic growth and the development of alternative energy sources since 1960s. In the case of pine forests of Miwa-cho, those in the early successional stage were few in number and small in patch size. Several woody plants covered under the pine canopy. The shade-tolerant shrub invaded into pine forest floor, because the undergrowth as a traditional energy source had no longer used. Pine forests were partly succeeded by deciduous oaks in Miwa-cho corresponding to the social changes. On the contrary in Yanghwa-ri, the vegetation replacement will not present because traditional management such as collecting fuels and making graveyards will be remained as a Korean ideology in the rural landscape.

Plant Structure and the Acceptability of Different Grasses to Sheep

Plant structure should be an important determinant of species acceptability to grazing ungulates functioning under various time-energy constraints. The acceptability of 9 grasses to sheep grazing a secondary grassland community in spring, summer, and autumn in South Africa was related to the following species attributes: plant height, leaf table height, tussock diameter, stemminess, percent leaf, leaf density, percent dry matter (DM), leaf tensile strength, and leaf crude protein (CP). Species acceptability over the grazing season was positively related to tussock diameter (P less than or equal to 0.05) but negatively related (P less than or equal to 0.01) to leaf tensile strength and DM. Discriminant function analysis successfully discriminated between species in different acceptability classes in summer (P less than or equal to 0.05) and autumn (P less than or equal to 0.01) using a combination of plant structure and leaf quality attributes. Correspondence analysis indicated that preferred species were generally short and nonstemmy and had leaves of low DM, low tensile strength, and high crude protein content. Conversely, avoided species tended to be tall and stemmy with a high leaf table height, and had leaves of high DM and tensile strength but low CP levels. It is concluded that, for sheep, acceptability is determined by a combination of plant structure and leaf quality attributes.

The Naturalized Flora of Hong Kong: A Comparison with Singapore

At least 144 exotic species of vascular plants have become naturalized in Hong Kong. The families As- teraceae, Poaceae and Fabaceae account for 45%. Of the total, 52% are probably introduced from tropical America, 18% from northern Eurasia (including Europe), 15% from Africa and Madagascar and 10% from tropical and subtrop- ical Asia. Recognizably exotic species are largely confined to open, recently-disturbed sites and have not significantly invaded the secondary grasslands and shrublands which cover most non-urban areas in Hong Kong. Only 48% of the Hong Kong species are also naturalized in Singapore. This is best explained by climatic differences. Hong Kong's cool winters apparently permit the establishment of exotics of temperate origin while excluding some tropical species.

Mediterrane Elemente in der Orchideenflora der Krim (UdSSR) )

On the Crimea 44 orchid species are known. Their occurrence is limited to the mountain forest region in the southern part of the peninsula. In the continental steppe region of the northern part orchids are absent. All orchids, growing on the Crimea, are geographically linked to the Mediterranean region, except six species, showing cireumboreal or wide Eurasian distribution patterns. Four Mediterranean-submediterranean range types may be distinguished, including 18 taxa coenologically linked to mesophilous oak forests, xerothermie bush forests and secondary grasslands in the Juniperus oxycedrus/excelsa-Quercus pubescens-altitudinal belt on the southern coast of Crimea. 12 species of (Mediterranean)-Middle European respectively wide European range types mainly occur in limestone beech forests in the Pinus pallasiana-Fagus sylvatica/orientalis-altitudinal belt. The distribution patterns of orchids are similar to those of characteristic wood and shrub species, dominating the vegetation on the southern coast of Crimea. The close phytogeographical relations between Crimean and Caucasian mountains, Anatolia, Balcan peninsula and Aegaean islands, showed by the occurrence of (east-) mediterranean orchids e.g., are based on the geological development of Black Sea region and on the mediterranoid climate of the southern coast of Crimea.

Dune vegetation dynamics from 1937 to 1976 in the Mlalazi-Richards Bay area of Natal, South Africa

Dune vegetation changes were studied qualitatively with the aid of air photos taken in 1937, 1957 and 1976.Results were transferred to 1:10 000 scale maps. In 1937 roughly 80% of the dune forest habitat was occupied by planted fields and post cultivation serai stages such as Secondary Grasslands and Dwarf Shrubland, Secondary Scrub and Acacia karroo Woodland. In three areas, the vegetation cover had been completely destroyed and drift sands had formed. In the 1950’s the trend of vegetation degradation was changed by the implementation of an afforestation programme by the Department of Forestry. The 1976 air photos indicate that the post cultivation serai stages of 1937 had been largely replaced by forest plantations. In secondary, unafforested areas the vegetation is evolving rapidly towards a Secondary Dune Forest.

Neighbour relationships in grass–legume communities. II. Temporal stability and community evolution

Surveys of three old pastures near London, Ontario, over a period of 2 years revealed three categories of plant associations important in community evolution: stable, seasonal, and temporary. These are considered as counterparts to stabilizing, directional, and disruptive selection pressures in species evolution. Trifolium repens is proposed as a major "driving force" in directing community evolution. It is suggested that seral stages in secondary grassland succession are manifested through seasonal and random associations, whereas stable associations characterize the approach to subclimax.

Species Diversity and Ecological Release in Caribbean Land Bird Faunas

Communities of breeding, non-raptorial land birds were studied in nine major habitat types (secondary grassland and scrub, young and old secondary forest, mature lowland forest, cloud forest, mangroves, savanna, residential land) in each of five Caribbean areas (Panama, Trinidad, Jamaica, St. Lucia, St. Kitts). In each habitat, the frequency of occurrence of individual species was determined in ten 20-min observation periods. Foliage height profiles were determined for all areas except St. Kitts. Data on frequency of occurrence were converted to indices of absolute abundance. Ecological release, involving both increase in the average number of habitats occupied per species and increase in within-habitat abundance, was extensive, and complete density compensation or overcompensation occurred in Jamaica, St. Lucia, and St. Kitts. Dropout of species along the species diversity gradient from Panama to St. Kitts appeared to be random with respect to generic or familial status. Habitat distribution appeared to shift from-being strongly influenced by interspecific relations in Panama to being largely independent of such influence in St. Kitts.

GRASSLAND EVOLUTION IN EUROPE

SummaryThis discussion deals primarily with the European secondary grassland, especially meadows and pastures. The principal constituents of this vegetation are about 20 species. Particular attention is paid to its evolution under the influence of man. In addition to the natives (members of natural vegetation cover) there are several species or races which are restricted to man‐made habitats. It is suggested that these latter are not native to the area of present distribution, but have immigrated under differentiation from abroad (the minor part) or evolved in situ (the major part). The significance of hybridization and introgression is stressed. It is contended that grassland evolution is still in progress, an important factor being the close interaction between cultivated grasses and their wild relatives in extra‐Mediterranean Europe, the center of diversity and origin of meadow and pasture grasses.

Utilization of the grazing resources by buffaloes in the Arusha National Park, Tanzania

SummaryThe purpose of the survey was to develop a meaningful method for assessing the utilization of the existing edaphic and serai grasslands in the park. Particular attention was given to the effect of grazing on the growth of different species of grasses, the course of plant succession and the fire hazard, in relation to the productivity and diversity of the environment. The distribution and composition of the different types of grassland are described and their suitability as pasture at different seasons is discussed.Utilization was assessed by recording the extent of short grass that is maintained by grazing in relation to the unused mature grass at different seasons of the year. Near optimum utilization of the edaphic (high water‐table) grasslands in the bottom lands takes place over a prolonged period. Utilization of the derived grasslands on the hills and uplands is increasing as the buffalo herds benefit by protection in the park. It is estimated that the available pastures can still accommodate an increased population of buffaloes and other grazing animals. Furthermore, advantages to the environment will accrue as a result of the reduced fire hazard.Buffaloes are the dominant grazing animals throughout and so mainly their impact on the vegetation is considered. The distribution and density of the buffalo population is recorded, and it is concluded that the existing number is well within the carrying capacity of the park. It is suggested that under‐grazing could be serious because of the increased fire risk that would result. In order to improve the grazing in the secondary grasslands preliminary trials for managing fire by patch burning have been successfully initiated.

公園車道の立地秩序計画について

This study aims at finding out the scientific method about location of park-road. In national park any road must be loated to adapt to its environment, especially to vegetation.Firstly, vegetation survey was, practiced around the Yamanobeno-michi Rord (Yamatoaogaki Quasi National Park, Nara Prefecture), which was located anciently, in order to find out the relation between location of road and vegetational environment. The table work after this survey shows 3 plant communities.1. Rhododendro-Pinetum kinkianum SUZ-TOK., nov.2. Quercus glauca-Dryopteris erythrosora communitya. Aphananthe aspera under communityb. Typical under communityThe Yamanobenomichi Road is located almost inAphananthe aspera under community.This community is the most fertile of these 3 communities. The result shows that ancient road is suited to its vegetational environment.Secondly, from this result, the planning process to locate roads in national park was mentioned. Consideration studied here is as follows.1. location survey (Standortsforschung)2. location analysis (Standortsanalyse)3. location diagnosis (Standortsdiagnose)4. location (planning) (Standortsdnungsplanung)After this process, the model planning in the Kurondoike-road (Kongo-Ikoma Quasi National Park, Nara Pretecture) was carried out. Along the road, 200m in width, vegetation was researched. The existing vegetation consists of the forest of Pinus densiflora, Alnus japonica and Phyllostachys pubescens, secondary forest of Quercus glauca-Quercus·serrata, Pinus densiflora-Quercus serrata, secondary grassland of Miscanthus sinensis, and cultivated land and paddy field. On the basis of these results, I drew an existing vegetation map and potential natural vegetation map of today in scale 1: 3, 000. The potential natural vegetation of today consists of 3 communities.1. Rhododendro-Pinetum kinkianum SUZ-TOK., nov.2. Alnus japonica forest3. Typical under community of Quercus-glauca-Dryopteris erythrosora communityOn the basis of these location survey and analysis, I diagnosed and classified the suitability of location of road and drew a location map in scale 1: 3, 000. And finally a planning map of location was made in scale 1: 3, 000, which contained a roadside planting plan.

The Influence of Edaphic Factors on the Species Composition of Early Stages of the Subsere

The secondary succession (subsere) on the sandy soils of the Transvaal Highveld has been described by Innes (1939), based on examination of disturbed sites of known history, and the terms ruderal stage, primary grass stage, secondary grass stage, grassland subclimax and scrub climax were proposed. It seems preferable to divide the early stages into communities which are distinctive when grazing and other biotic factors operate, and the following stages are proposed:

Production of antibiotic substances by the roots of a grass, Trachypogon plumosus (H.B.K.) Nees, and of Pentanisia variabilis (E. Mey.) Harv; Rubiaceae.

DURING the course of a study of the rate of nitrification in soils taken from plant communities representing various stages of the secondary grassland succession on the Transvaal Highveld, it was found that soils taken from the Trachypogon plumosus grassland climax community showed a consistent lag in the production of nitrate.