Vegetation diversity of the Brand-se-Baai coastal dune area,west coast,South Africa: a pre-mining benchmark survey for rehabilitation

Prior to the mining of heavy minerals, the vegetation diversity of the Brand-se-Baai coastal area was investigated to serve as a benchmark for the future rehabilitation of the area. The vegetation was surveyed using the Braun–Blanquet procedure to classify the different plant communities. Six plant communities, some of which include several variants, were identified, described and mapped. A revegetation goal of 30 per cent, rather than 60 per cent, of the number of plant species present prior to mining are recommended. Copyright © 1999 John Wiley & Sons, Ltd.     

Phytosociology,structure and dynamics of Pinus roxburghii associations from Northern Pakistan

We investigated the phytosociology, structure and dynamics of Pinus roxburghii in 40 stands in northern areas of Pakistan by using cluster analysis （Ward’s agglomerative clustering） and ordination （Non-metric Multidimensional Scaling）. Cluster analysis revealed three major groups associated with specific environmental characteristics： （1） P. roxburghii （2） Pinus-Quercus baloot and （3） Pinus-Olea ferruginea community types. NMS-ordination showed the major gradient as an amalgam of elevation （r2=0.441, p＆lt;0.01） and slope （r2=0.391, p＆lt;0.05） as the two topographic factors correlated with species distribution. The first ordination axis also showed positive correlation with soil variables like pH and electrical conductivity, suggesting that soil chemistry was related to topographic characteristics and probably acted as a secondary gradient. We also examined size class distributions, age structures and growth rates of the three communities in order to describe community development and dynamics. Total tree density was 14700 plants/ha, with P. roxburghii having a relative density of 82%to 100%. Density of juve-nile and total density and basal area of the subordinate tree species were low. The low density of trees in the smallest diameter size-class sug-gested that the recruitment of small P. roxburghii plants into the adult population may be lower than the required replacement rate for the stands. Pooled size-class distributions for the species showed a multimo-dal pattern with some regeneration gaps. Browsing, heavy logging and＆amp;nbsp;other anthropogenic activities were the overriding factors responsible for the poor recruitment of P. roxburghii. We concluded from the age struc-ture that the forests were characterized by the dominance of young trees. Growth rate analysis revealed that P. roxburghii was the fastest growing species among the conifers species in Pakistan. In view of its relatively fast growth and longevity, P. roxburghii seems to be a suitable choice for short-t     

Woody vegetation of protected areas in northern Togo. Cases of Barkoissi,Galangashi and Oti-Keran: ecological and structure analyses of plant communities

The 170 samples obtained from ligneous investigation in Barkoissi, Galangashi and Oti-Keran protected areas (northern -     

Effect of abiotic factors on understory community structures in moist deciduous forests of northern India

Understory vegetation controls, in a significant way, the regeneration of overstory trees, carbon sequestration and nutrient retention in tropical forests. Development and organization of understory vegetation depend 3n climate, edaphic and biotic factors which are not well correlated with plant community structures. This study aimed to ~xplore the relationships between understory vegetation and abiotic factors in natural and planted forest ecosystems. A non-metric multidimensional scaling （NMS） ordination technique was applied to represent forest understory vegetation among five forest communities, i.e., a dry miscellaneous forest （DMF）, a sal mixed forest （SMF）, a teak plantation （TP）, a low-land miscellaneous forest （LMF） and a savanna area （SAV） of the Katerniaghat Wildlife Sanctuary, located in northern India. Microclimatic variables, such as photosynthetically active radiation （PAR）, air temperature （AT）, soil Lemperature （ST）, ambient atmospheric CO2 concentration, absolute air humidity （AH）, physical and chemical soil ~roperties as well as biological properties were measured. Understory species were assessed via 100 random quadrats （5 m x 5 m） in each of the five forests in which a total of 75 species were recorded encompassing 67 genera from 37 families, consisting of 32 shrubs and 43 plant saplings. DMF was the most dense forest with 34,068 understory individuals per ha of different species, whereas the lowest understory population （13,900 per ha） was observed in the savanna. Ordination and correlation revealed that microclimate factors are most important in their effect compared to ~daphic factors, on the development of understory vegetation in the various forest communities in the north of India.     

Habitat,occurrence and conservation status of the Saharo-Macaronesian and Southern-Mediterranean element Fagonia cretica L.(Zygophyllaceae) in Italy

Fagonia cretica L. is an important component of Mediterranean dry grasslands and a rare and isolated species of Italian flora. In this study, an assessment is presented on the distribution, habitat, and conservation status of F. cretica in Italy. The results of field investigation and herbarium analysis show that this species grows in a small area within the southern Calabria region characterized by a warmest and driest Mediterranean climate on the Italian peninsula. F. cretica is a semi-desert plant species growing in Italy in only one peripheral and isolated population at the northern limit of its distribution. Plant community analysis, using the phytosociological method, shows that F. cretica grows in wintergreen perennial dry grasslands dominated by Lygeum spartum and Hyparrhenia hirta. F. cretica plant communities are located in thermo-xeric habits such as south-, southeast-and east-facing slopes on clays and sandy clays in southern Calabria. The population of F. cretica is fragmented in six neighbouring localities, with two of which belonging to a Site of Community Importance(SCI). The conservation status of F. cretica population is not very good, and is defined as "Critically Endangered" in accordance with IUCN criteria. There are many threats affecting the F. cretica population in Italy, primarily the changes in land uses due to urban expansion and reforestation with exotic plants. The southern end of the Italian peninsula hosts other plants from thermo-xeric habits that do not adapt to the current local climate. This territory can be considered as a microrefugia for plants currently distributed in the arid territory of the southern Mediterranean. These results contribute to the discussion of some conservation measures, and the possibility of establishing a micro-reserve. For all these reasons, we propose to include F. cretica in the lists of protected plant species at regional(Calabria) and country(Italy) scales in Italy.     

Productivity status of traditional agrisilviculture system on northern and southern aspects in mid-hill situation of Garhwal Himalaya, India

The productivity of traditional agrisilviculture system (agricultural crops + trees) was investigated in the northern and southern aspects of mid-hill situation in Garhwal Himalaya, Uttarakhand, India during the 2004-2006. A total of 19 tree species were studied in both northern and southern aspects, out of which 17 tree species were selected in northern aspect and 12 tree species in southern aspect for phytosociological characteristic analysis of trees in agrisilvicultural system. The most dominant tree species are Grewia optiva, Celtis australis and Melia azedarach and successively grown under traditional agrisilviculture system. The results show that the annual productivity of all tree species was 3775 kg·ha-1·a-1 in northern aspect (site-N) and 3101 kg·ha-1·a-1 in southern aspect (site-S). G. Optiva had the highest productivity in both site-N and site-S among the tree species, followed by M. Azedarach, Quercus leucotrichophora and C. Australis. The dominant agricultural crops were Eleusine coracana in summer cereals, Phaseolus vulgaris in summer pulses-oilseeds and Triticum aestivum in the winter season in the area. The average biological productivity of agricultural crops in northern aspect was about 16% higher than that in southern aspect under traditional agrisilviculture system. The sole agricultural crop productivity (without trees) in northern aspect was also higher than that in southern aspect. An obvious difference in annual productivity of trees and agriculture crops was observed between northern aspect and southern aspect. The overall productivity in traditional agrisilviculture system (crop + tree) was 24% (in northern aspect) and 21% (in southern aspect) higher than that in sole cropping system.     

Stable or changing lakes? a classification of aquatic macrophyte assemblages from a eutrophic shallow lake system in the United Kingdom

1. It is proposed that an appreciation of patterns of change and stability in macrophyte floras is an important tool for lake managers. 2. The presence and abundance of aquatic macrophytes was annually monitored (from 1983 to 1995) along permanent transects in 13 shallow lakes in the Broads wetland in eastern England, United Kingdom. 3. Cluster analysis (TWINSPAN) revealed three Broad Macrophyte Types (BMTs) or assemblages. Two of these were sub-divided into four and then again into six sub-types. BMT1 had a constant presence (i.e. in more than 60% of all samples) of charophytes, Potamogeton pectinatus L.,Myriophyllum spicatum L. and Najas marina L. BMT2 had a constant presence of Nuphar lutea (L.) Smith and filamentous algae. BMT3 consisted of sites without macrophytes. 4. The BMTs provided a useful regional classification for aquatic vegetation in shallow, calcareous, and slightly brackish lakes with relatively organic sediments. The BMTs were compared with national and international classifications. The value of BMTs as conservation targets was assessed. 5. Analysis of changes of macrophyte assemblages with time, using ordination (CANOCO) and time-series plots, revealed lakes with stable, drifting, or erratic and unstable macrophyte assemblages. 6. The method of presentation used facilitates the interpretation of year-to-year macrophyte changes. The implication is that management effort can be more effectively directed towards conservation targets. The effects of management on the aquatic flora, such as dredging and biomanipulation, were shown to be easily evaluated using Cockshoot Broad as an example. © 1998 John Wiley & Sons, Ltd.     

牧压梯度上呼伦贝尔典型草原植物群落学特征

植物群落学分析以演绎式的生态解释转向归纳式的实验研究。本文运用法瑞学派(Braun-Blanquet)调查分析和群落功能群分类方法,通过比较内蒙古呼伦贝尔克氏针茅草原不同放牧梯度上群落组成结构、特征种及群丛单位的变化,阐明群落物种组合规律。结果显示:根据Braun-Blanquet存在度/盖度等级的划分,得到两个主要群丛及下属两个亚群丛;随着放牧强度的增强,葱属植物等耐牧、耐旱物种出现频度显著增加,适口性好、耐牧能力弱的物种出现频度降低甚至消失;群落科构成和功能群类型在牧压梯度上呈现不同的变化特征,群落物种数和多样性指数具有显著差异。     

Seedbank phytosociology of the Strandveld Succulent Karoo,South Africa: a pre‐mining benchmark survey for rehabilitation

Prior to the mining of heavy minerals, the seedbank of the Strandveld Succulent Karoo was investigated to serve as a benchmark for the future rehabilitation of the area. Seedbank composition and species' abundance were determined with the seedling emergence method. By using the Braun‐Blanquet method, five main vegetation units were identified in concordance with results obtained for the standing vegetation. A total of 108 species were recorded in the seedbank, which represents c. 50 per cent of the species recorded in the standing vegetation of the total study area. Seven annual species (3 per cent) were unique to the soil seedbank. On community level, similarity in species composition between the standing vegetation and the soil seedbank ranged between 39·2 per cent and 48·8 per cent, with a similarity of 54·3 per cent for the total study area. Annual and perennial species' similarity in species composition between the standing vegetation and the seed bank totalled 74·8 per cent and 43·1 per cent respectively. Post‐mining topsoil replacement as well as seeding and transplanting of selected local species will be essential to revegetate this area. Copyright © 2001 John Wiley & Sons, Ltd.