Lipid concentration and composition in xylem sap of woody angiosperms from a tropical savanna and a seasonal rainforest

Lipids may play an important role in preventing gas embolisms by coating nanobubbles in xylem sap.Few studies on xylem sap lipids have been reported for temperate plants,and it remain unclear whether sap lipids have adaptational significance in tropical plants.In this study,we quantify the lipid composition of xylem sap for angiosperm species from a tropical savanna(seven species)and a seasonal rainforest(five species)using mass spectrometry.We found that all twelve species studied contained lipids in their xylem sap,including galactolipids,phospholipids and triacylglycerol,with a total lipid concentration ranging from 0.09 to 0.26 nmol/L.There was no difference in lipid concentration or composition between plants from the two sites,and the lipid concentration was negatively related to species’open vessel volume.Furthermore,savanna species showed little variation in lipid composition between the dry and the rainy season.These results support the hypothesis that xylem sap lipids are derived from the cytoplasm of individual conduit cells,remain trapped inside individual conduits,and undergo few changes in composition over consecutive seasons.A xylem sap lipidomic data set,which includes 12 tropical tree species from this study and 11 temperate tree species from literature,revealed no phylogenetic signals in lipid composition for these species.This study fills a knowledge gap in the lipid content of xylem sap in tropical trees and provides additional support for their common distribution in xylem sap of woody angiosperms.It appears that xylem sap lipids have no adaptive significance.

Influence of Human Activity Intensity on Habitat Quality in Hainan Tropical Rainforest National Park,China

Due to long-term human activity interference,the Hainan Tropical Rainforest National Park(HTRNP)of China has experienced ecological problems such as habitat fragmentation and biodiversity loss,and with the expanding scope and intensity of human activity impact,the regional ecological security is facing serious challenges.A scientific assessment of the interrelationship between human activity intensity and habitat quality in the HTRNP is a prerequisite for achieving effective management of ecological disturbances caused by human activities and can also provide scientific strategies for the sustainable development of the region.Based on the land use change data in 2000,2010,and 2020,the spatial and temporal variations and the relationship between habitat quality(HQ)and human activity intensity(HAI)in the HTRNP were explored using the integrated valuation of ecosystem services and trade-offs(InVEST)model.System dynamics and land use simulation models were also combined to conduct multi-scenario simulations of their relationships.The results showed that during 2000–2020,the habitat quality of the HTRNP improved,the intensity of human activities decreased each year,and there was a negative correlation between the two.Second,the system dynamic model could be well coupled with the land use simulation model by combining socio-economic and natural factors.The simulation scenarios of the coupling model showed that the harmonious development(HD)scenario is effective in curbing the increasing trend of human activity intensity and decreasing trend of habitat quality,with a weaker trade-off between the two compared with the baseline development(BD)and investment priority oriented(IPO)scenarios.To maintain the authenticity and integrity of the HTRNP,effective measures such as ecological corridor construction,ecological restoration,and the implementation of ecological compensation policies need to be strengthened.

A test of the mycorrhizal-associated nutrient economy framework in two types of tropical rainforests under nutrient enrichments

Shifts in tree species and their mycorrhizal associations driven by global change play key roles in biogeochemical cycles. In this paper, we proposed a framework of the mycorrhizal-associated nutrient economy(MANE), and tested it using nutrient addition experiments conducted in two tropical rainforests. We selected two tropical rainforests dominated by arbuscular mycorrhizal(AM) and ectomycorrhizal(ECM) trees, and established eighteen20 m×20 m plots in each rainforest. Six nitrogen(N) and phosphorus(P) addition treatments were randomly distributed in each rainforest with three replicates. We examined the differences in soil carbon(C) and nutrient cycling, plant and litter productivity between the two rainforests and their responses to 10-year inorganic N and P additions. We also quantified the P pools of plants, roots, litter, soil and microbes in the two rainforests. Overall,distinct MANE frameworks were applicable for tropical rainforests, in which soil C, N and P were cycled primarily in an inorganic form in the AM-dominated rainforest, whereas they were cycled in an organic form in the ECMdominated rainforest. Notably, the effects of mycorrhizal types on soil P cycling were stronger than those on C and N cycling. The intensified N and P deposition benefited the growth of AM-dominated rainforests instead of ECMdominated rainforests. Our findings underpin the key role of mycorrhizal types in regulating biogeochemical processes, and have important implications for predicting the ecological consequences of global changes.

Phyllosphere eukaryotic microalgal communities in rainforests:Drivers and diversity

Phyllosphere algae are common in tropical rainforests,forming visible biofilms or spots on plant leaf surfaces.However,knowledge of phyllosphere algal diversity and the environmental factors that drive that diversity is limited.The aim of this study is to identify the environmental factors that drive phyllosphere algal community composition and diversity in rainforests.For this purpose,we used single molecule real-time sequencing of full-length 18S rDNA to characterize the composition of phyllosphere microalgal communities growing on four host tree species(Ficus tikoua,Caryota mitis,Arenga pinnata,and Musa acuminata) common to three types of forest over four months at the Xishuangbanna Tropical Botanical Garden,Yunnan Province,China.Environmental 18S rDNA sequences revealed that the green algae orders Watanabeales and Trentepohliales were dominant in almost all algal communities and that phyllosphere algal species richness and biomass were lower in planted forest than in primeval and reserve rainforest.In addition,algal community composition differed significantly between planted forest and primeval rainforest.We also found that algal communities were affected by soluble reactive phosphorous,total nitrogen,and ammonium contents.Our findings indicate that algal community structure is significantly related to forest type and host tree species.Furthermore,this study is the first to identify environmental factors that affect phyllosphere algal communities,significantly contributing to future taxonomic research,especially for the green algae orders Watanabeales and Trentepohliales.This research also serves as an important reference for molecular diversity analysis of algae in other specific habitats,such as epiphytic algae and soil algae.

Soil Seed Bank Characteristics in Congolese Rainforests and Implications for Post-Logging Plots Reforestation

The soil seed bank is considered as an important mechanism for the natural regeneration, resilience and conservation of the forests after disturbances. This study evaluates the characteristics of the soil seed bank in two post-logging plots of Loundoungou-Toukoulaka Forest Management Unit: one plot exploited in 2008 and another exploited in 2021. In each study plot, 40 samples were collected per soil layer (0 - 5 cm, 5 - 10 cm, 10 - 15 cm, 15 - 20 cm and 20 - 25 cm depth). The species diversity and abundance of the soil seed bank were estimated after soil samples were brought to germination. The results demonstrated that 347 seedlings belonging to 37 species in the plot exploited in 2008 and 418 seedlings belonging to 27 species in that exploited in 2021 germinated during 20 weeks of monitoring. The total densities of the seedlings identified were respectively 1446 seedlings/m2 and 1742 seedlings/m2. The plot exploited in 2021 presented a higher proportion of herbaceous species (93.78%) compared to that exploited in 2008 (82.71%). Two pioneer species were recorded in the plot exploited in 2008. These are Macaranga barteri (0.29%) in the 0 - 5 cm layer and Musanga cecropioides (2.31%) up to 20 cm deep. On the other hand, in the plot exploited in 2021, Macaranga spinosa (0.96%) in the 0 - 5 cm layer and M. cecropioides (0.96%) up to 20 cm deep were identified. In the plot exploited in 2008, the 20 - 25 cm layer demonstrated important proportions in woody species (9%), these are in particular Rubiaceae sp.4 and Nauclea diderrichii. While that exploited in 2021, presented 19% of woody species, namely the species of Rubiaceae sp.4, Rubiaceae sp.5 and N. diderrichii, greatly exceeding the proportions obtained in the 15 - 20 cm layer of the two plots. Nonetheless, N. diderrichii was the only commercial species recorded with densities of 108 seedlings/m2 and 4 seedlings/m2, respectively in the plot exploited in 2008 and that exploited in 2021. Commercial tree species are poorly represented in the soil seed bank. Consequently, the study suggests that to improve the natural regeneration of the commercial species, silvicultural interventions based on planting techniques in the exploited plots should be more effective in order to sustainably manage these production forests.

THE FLORISTIC CHARACTERISTICS OF THE TROPICAL RAINFOREST IN XISHUANGBANNA

ＴＨＥ ＦＬＯＲＩＳＴＩＣ ＣＨＡＲＡＣＴＥＲＩＳＴＩＣＳ ＯＦ ＴＨＥ ＴＲＯＰＩＣＡＬ ＲＡＩＮＦＯＲＥＳＴ ＩＮ ＸＩＳＨＵＡＮＧＢＡＮＮＡ ＺｈｕＨｕａ（朱华）（ＸｉｓｈｕａｎｇｂａｎｎａＴｒｏｐｉｃａｌＢｏｔａｎｉｃａｌＧａｒｄｅｎ，ｔｈｅ...

THE TROPICAL RAINFOREST VEGETATION IN XISHUANGBANNA

The tropical rainforest in Xishuangbanna, Yunnan Province of China, is introduced in detail in this paper. Situated at the northern margin of tropical mainland SE Asia and controlled by monsoon climate, the region has been climatically at the lower limits for tropical rainforests, however true tropical rainforests exist and develop luxuriantly in the region. The reasons for this are discussed. In general phytocoenological characteristics such as vertical stratification, life form spectrum, species riches etc. the tropical rainforest in Xishuangbanna is very similar to the typical tropical rainforest in equatorial region, but it is characterized by a clear change of physiognomy between different season. As occurred at the latitudinal and altitudinal limits of tropical rainforest, the flora of the rainforest is endowed with the nature of northern margin of tropical zone of SE Asia and is transitional toward the flora of subtropical forest of China. In recent years the region has been opened up to use in

Characteristics of typhoon disturbed gaps in an old-growth tropical montane rainforest in Hainan Island, China

Disturbances that create gaps can shape the structure and function of forests. However, such disturbance regimes in Asian tropical montane rainforests remain largely unquantified. Least studied are typhoon disturbances that are attributable to climate change. We investigated gap characteristics in terms of size, age, and gap-maker to quantify the gap disturbance regimes in an intact old-growth tropical montane rainforest on Hainan Island, China. The intensity of typhoons has increased since 1949, and typhoon winds blow mostly (45.5%) from the northeast corner of Hainan Island, resulting in a higher frequency of gaps in the northeast. A total of 221 gap-makers (trees that fell to create canopy gaps) and 53 gaps were observed in a 3.16 ha old-growth rainforest. Most canopy gaps (85%) were < 200 m(2). The average size of canopy gaps was smaller in the rainforest than in other tropical forests, while the average size of expanded gaps was similar to those in other tropical forests. The maximum age of gaps was 23.5 years indicating that gaps had more rapid turnover than other parts of tropical forests. The frequency distribution of gap-makers followed a lognormal distribution with a distinctive peak at three gap-makers, which was different from the inverse J-shaped curve typical of other tropical forests. Gaps were recorded mainly on slopes between 20A degrees and 35A degrees and wood density of gap-makers was between 0.6 and 0.7 g cm(-3). Our results suggest that small-scale disturbance was the dominant agent of gap formation in this old-growth rainforest that is subject to increasing typhoon disturbances.

The global rainforest mapping project JERS-1: a paradigm of international collaboration for monitoring land cover change

The Global Rainforest Mapping (GRFM) project was initiated in 1995 and, through a dedicated data acquisition policy by the National Space Development Agency of Japan (NASDA), data acquisitions could be completed within a 1.5-year period, resulting in a spatially and temporally homogeneous coverage to contain the entire Amazon Basin from the Atlantic to the Pacific; Central America up to the Yucatan Peninsular in Mexico; equatorial Africa from Madagascar and Kenya in the east to Sierra Leone in the west; and Southeast Asia, including Papua New Guinea. To some extent, GRFM project is an international endeavor led by NASDA, with the goal of producing spatially and temporally contiguous Synthetic Aperture Radar (SAR) data sets over the tropical belt on the Earth by use of the JERS-1 L-band SAR, through the generation of semi-continental, 100m resolution, image mosaics. The GRFM project relies on extensive collaboration with the National Aeronautics and Space Administration (NASA), the Joint Research Center of the European Commission (JRC) and the Japanese Ministry of International Trade and Industry (MITI) for data acquisition, processing, validation and product generation. A science program is underway in parallel with product generation. This involves the agencies mentioned above, as well as a large number of international organizations, universities and individuals to perform field activities and data analysis at different levels.

Rainforests north of the Tropic of Cancer: Physiognomy, floristics and diversity in ‘lowland rainforests’ of Meghalaya, India

The lowland rainforests of Meghalaya, India represent the westernmost limit of the rainforests north of the Tropic of Cancer. These forests, on the Shillong plateau, are akin to Whitmore's ‘tropical lowland evergreen rainforest' formation and exhibit striking similarities and conspicuous differences with the equatorial rainforests in Asia-Pacific as well as tropical seasonal rainforests in southwestern China near the Tropic of Cancer. We found these common attributes of the rainforests in Meghalaya: familial composition with predominance of Euphorbiaceae, Lauraceae, Meliaceae, Moraceae, Myrsiticaceae,Myrtaceae and Rubiaceae; deciduousness in evergreen physiognomy; dominance of mega-and mesophanerophytic life-forms; abundance of species with low frequency of occurrence(rare and aggregated species); low proportional abundance of the abundant species; and truncated lognormal abundance distribution. The levels of stand density and stand basal area were comparable with seasonal rainforests in southwestern China, but were lower than equatorial rainforests. Tropical Asian species predominated flora, commanding 95% of the abundance. The differences include overall low stature(height) of the forest, inconspicuous stratification in canopy, fewer species and individuals of liana, thicker understory,higher proportion of rare species, absence of locally endemic species and relatively greater dominance of Fagaceae and Theaceae. The richness of species per hectare(S) was considerably lower at higher latitudes in Meghalaya than in equatorial rainforests, but was comparable with seasonal rainforests. Shannon's diversity index(H’=4.40 nats for ≥10 cm gbh and 4.25 nats for ≥30 cm gbh) was lower on higher latitudes in Meghalaya in comparison to species-rich equatorial rainforests, but it was the highest among all lowland rainforests near the Tropic of Cancer.

Population distribution and threats to sustainable management of selected non-timber forest products in tropical lowland rainforests of south western Nigeria

Uncontrolled harvesting of non-timber forest products （NTFPs） poses a serious risk of extermination to several of these species in Nigeria. Yet, there is a paucity of information on the distribution, population status and sustainable management of NTFPs in most of the tropical lowland rainforests. We, therefore, assessed the population, distribution and threats to sustainable management of NTFPs within the tropical lowland rainforests of Omo and Shasha Forest Reserves, south western Nigeria. Data were obtained through inventory surveys on five top priority species including： bush mango （Irvingia gabonensis （Aubry-Lecomte ex O’Rorke） Baill）, African walnut （Tetracarpidium conophorum （Mull. Arg.） Hutch. ＆ Dalziel syn. Plukenetia conophora）, chew-stick （Massularia acuminata （G. Don） Bullock）, fever bark （Annickia chlorantha Setten ＆ P.J.Maas syn. Enantia chloranta） and bush pepper （Piper guineense Schumach. ＆ Thonn.）. Purposive and stratified random sampling techniques were used for the inventory. Each forest reserve was stratified into three, viz： less disturbed natural forest （for areas that have been rested for at least ten years）, recently disturbed natural forest （for areas that have suffered one form of human perturbation or the other in the last five years）, and plantation forest （for areas carrying forest plantation）. Data were collected from eighteen 10 m × 500 m belt transects located in the above strata. The species were generally fewer in both plantation and recently disturbed natural forest than the less disturbed natural forest, suggesting that forest disturbances （habitat modification） for other uses may have an effect on the occurrence and densities of the NTFPs. Exceptions to this trend were found for P. guineense and T. conophorum, which were fairly common in both plantation and recently disturbed natural forest. Among three tree NTFP species （i.e. I. gabonensis, M. acuminata and A. chlorantha）, only I. gabonensis showed a significant difference in overall DBH size classes for both reserves （t=？2.404; df =21; p=0.026）. Three tree NTFP species in both reserves further showed differences from the regular patterns of distribution of trees. The fairly regular reverse J-shaped size class distribution observed for M. acuminata in the study sites, however, suggests a recuperating population. In general, destructive harvesting of species, logging operations, low population size, narrow distribution ranges and habitat degradation are the major threats to the population of NTFPs in the study area. The implications of our findings for sustainable management of NTFPs in the study area are discussed and recommendations are made for a feasible approach towards enhancing the status of the species.

Responses of soil CH_(4) fluxes to nitrogen addition in two tropical montane rainforests in southern China

Background:Atmospheric nitrogen(N)deposition is projected to increase in the next few decades,which may have a marked impact on soil-atmosphere CH_(4) fluxes.However,the impacts of increased atmospheric N depositions on soil CH_(4) flux in tropical rainforests are still poorly understood.From January 2015 to December 2018,a field experiment was conducted in a primary tropical montane rainforest(PTMR)and a secondary tropical montane rainforest(STMR)in southern China to quantify the impact of N additions at four levels(N0:0 kg N⋅ha^(-1)⋅year^(-1);N25:25 kg N⋅ha^(-1)⋅year^(-1);N50:50 kg N⋅ha^(-1)⋅year^(-1);N100:100 kg N⋅ha^(-1)⋅year^(-1)on soil CH_(4) flux.Results:Four years of measurements showed clear seasonal variations in CH_(4) flux in all treatment plots for both forest types(PTMR and STMR),with lower rates of soil CH_(4) uptake during the wet season and higher rates of soil CH_(4) uptake during the dry season.Soil CH_(4) uptake rates were significantly and negatively correlated with both soil temperature and soil moisture for both forest types.Annual CH_(4) uptake for the N0 plots from the PTMR and STMR soils were2.20 and1.98 kg N⋅ha^(-1)⋅year^(-1),respectively.At the PTMR site,mean CH_(4) uptake compared with the N0 treatment was reduced by 19%,29%,and 36%for the N25,N50,and N100 treatments,respectively.At the STMR site,mean CH_(4) uptake compared with the N0 treatment was reduced by 15%,18%,and 38%for the N25,N50,and N100 treatments,respectively.High level N addition had a stronger inhibitory impact on soil CH_(4) uptake than did the low level N addition.Conclusion:Our data suggest that soil CH_(4) uptake in tropical rainforests is sensitive to N deposition.If atmospheric N deposition continues to increase in the future,the soil CH_(4) sink strength of tropical rainforests may weaken further.

Assessing Tropical Deforestation and Biodiversity Loss in the Cross River Rainforest of Nigeria

The Cross River Rainforest of South Eastern Nigeria is one of Africa’s last remaining areas of pristine tropical high forest, extremely rich in a wide variety of flora and fauna species, and is among the twenty five biodiversity hotspots in the world. The forest has important biophysical properties which affect local, regional and global environmental quality. Using a combination of document research, GIS report, field observations, interviews and focus group discussions, the study reveals that the ecological integrity of this forest is being seriously threatened by a myriad of human activities, such as unsustainable agricultural practices, illegal logging, population explosion/expansion of human settlements, construction of highways, mining activities, and high unemployment/pressure on natural resources. All the above factors have combined to impact heavily on the depletion and extinction of valuable flora and fauna species in the region. Rigorous research-based innovative forestry and biodiversity policies and programmes, forest restoration initiatives, community-based forest management, and sustainable land use practices are recommended to save the Cross River Rainforest from total destruction.

Hydrological Controls on Nutrient Exportation from Old-Growth Evergreen Rainforests and <i>Eucalyptus nitens</i>Plantation in Headwater Catchments at Southern Chile

Soil cover disturbances have a direct effect on biogeochemistry, potentially enhancing nutrient loss, land degradation and associated changes in ecosystem services and livelihood support. The objective of this study was to assess how canopy affected throughfall chemistry and how hydrology affected stream nutrient load responses in two watersheds dominated by native old-growth evergreen rainforest (NF) and exotic plantation of Eucalyptus nitens (EP), located at the Coastal mountain range of southern Chile (40&deg;S). We measured nitrogen (NO3-N, NH4-N, Organic-N, Total-N) and total phosphorus (Total-P) at catchment discharge, and δ18O in throughfall precipitation and stream discharge in both catchments, in order to separate throughfall (or new water) contributions during storm events. It was hypothesized that all nutrients showed an increase in concentration as discharge increased (or enhanced hydrological access), in EP;but not in NF. Our results indicated that Organic-N, Total-N and Total-P concentrations were positively related to discharge. However, NO3<sup style="margin-left:-7px;">--N showed a negative correlation with catchment discharge. Organic-N and Total-P showed a flush during storm events;the opposite was observed for NO3<sup style="margin-left:-7px;">--N. However, this behavior suggested that NO3<sup style="margin-left:-7px;">--N was being retained by charged particles or soil micro biota, whether Organic-N was flushed as it was more concentrated in big pore water that was not tightly attached, compared with NO3<sup style="margin-left:-7px;">--N.

Blood and Gastrointestinal Parasites of Chickens and Turkeys Reared in the Tropical Rainforest Zone of Southeastern Nigeria

The blood and gastrointestinal (GI) parasites of chickens and turkeys reared in Owerri, Southeastern Nigeria were studied. Out of 5600 birds, 5040 (90%) were chickens and 560 (10%) were turkeys. Of these birds, 672 (12%) were infected with blood parasites, of which 448 (8.9%) were chickens and 224 (40%) turkeys. The blood parasites found in chickens were Leucocytozoon sp., with a prevalence rate of 448 (8.9%) occurring in both male and female chickens examined. Plasmodium sp. was found in the turkeys and it gave a prevalence of 224 (40%). 1792 (32%) of the birds were infected with faecal parasites, out of which, 1456 (28.9%) were chickens and 336 (60%) turkeys examined. Ascaridia sp. infected 1232 (24.4%) of the chickens and 336 (60%) of the turkeys were examined. The only cestode observed was Raillietina spp., which infected 224 (4.4%) of the chickens, but none in the turkeys. Generally, low blood and faecal infections were observed in the chickens, while infections in the turkeys were slightly higher.

Ecosystems Restoration Strategies for the Cross River Rainforest Zones. Preparing Forest Stakeholders for the UN Decade on Ecosystems Restoration 2021 to 2030

This paper set out to chart a pathway for the restoration of rainforest ecosystems in Cross River State in line with the United Nations declaration of years 2021-2030 as the Decade on Ecosystems restoration. The paper looked at the essence of ecosystems restoration and zeroed-in on forest restoration, it touched on the problems such as the impairment of biodiversity and land productivity as well as causes of rainforest ecosystems degradation which included among other conversions of forests to other uses, ignorance on the part of community members. The paper proceeded to address some strategies for ecosystem restoration to include reforestation, afforestation, Environmental Education, preservation and conservation among other strategies. It was concluded that if these strategies are followed, the decades objectives will be achieved. It was recommended that government should incorporate the Cross River National Park in the implementation of the forthcoming decade, partnership should be enhanced amongst stakeholders to ensure smooth observance of the decade and that the policy of placing a moratorium on logging in the state should be re-activated and enforced effectively as a precursor to the beginning of the decade while aggressive Environmental Education should be carried out at both community and regional levels.

The Survival and Vegetative Growths of a 60 Month-Old Tropical Rainforest Tree Species Trial Established under a Hopea odorata Nurse Stand at an Ex-Tin Mine in Peninsular Malaysia

AFoCo(Asian Forest Cooperation)Project in 2011 has funded a research and development project in Malaysia for enriching a mono-species stand established in an ex-tin mine.The project covered only for a period of 12 months.A study plot of 1 ha size was established in TTAC(Tin Tailings Afforestation Centre).Twenty indigenous tropical rainforest tree species were planted and their five year-old survival count,diameter and H(top height)growths are reported in this study.Some of them are red list species of IUCN(International Union of Conservation of Nature).The survival of the 1 ha planting trial was 53%.Mortality of the tree species is mainly caused by wild boars.The tropical rainforest tree species in this planting trial had similar growth to those planted at good mineral soils.This paper also documented the tending treatments which were implemented during post-planting that have contributed to healthy growth of the mixed-species stand.The mixed-species stand is being properly tended till to-date and hence sustained growth of the stand is anticipated.

Origin of the Amazonian Rainforest

In the last 30 ma, the passive continental margin of South America and the Amazonian basin experienced three periods of major sea level inundation;viz. at around 20 ma, at around 10 ma and at around 3 ma. The establishment of the immense Amazonian rainforest ecosystem covering some 6 million square km can neither have occurred during the periods of high sea level nor at the intermediate periods of arid or semi-arid climatic conditions. Therefore, the origin of the Amazonian rainforest of present-day dimensions must be set at the Late Miocene. The establishment of the Amazonian rainforest implied the withdrawal of enormous quantities of water from the global hydrological cycle. The drastic increase in evaporation leading to the Messinian salinity crisis in the Mediterranean occurred at the same time as the Amazonian rainforest (sensu hodierno) establishment suggesting a causal linkage.

One More Reason to Save the Rainforest

As we all know by now,the large rainforests scattered around the world,and the Amazon Rainforest in particular,are the'lungs'of our planet.They soak up much of the carbon dioxide we produce and give us life-sustaining oxygen in return.

Floristic Composition, Diversity and Structure of the Rainforest in the Mayoko District, Republic of Congo

Botanically, the Mayoko district is known only through anecdotal descriptions made in the colonial era. The present study was undertaken as part of the prerequisite for a mining feasibility study where a benchmark of the floristic composition, diversity and structure of the vegetation was needed to evaluate potential biodiversity offset areas and to guide species selection for post-mining re-vegetation. The study area comprised approximately 160,000 ha and 235 sample sites were surveyed using the Braun-Blanquet method of phytosociology. Diversity of each plant association was expressed in terms of various diversity parameters. Twelve associations were described and mapped. The associations ranged from highly disturbed and degraded to fairly intact forest associations. A wet to dry gradient and permanently inundated to temporary inundated gradient could also be distinguished. The approach followed here proved remarkably robust in illustrating the complexity in a topographically complex region of the Chaillu Massif. The data provided a high level of insight into the possible dynamics of the rainforest and indications as to possible successional pathways. This information provides a better level of understanding of forest structure and evolution potential than studies limited to trees, remote sensing carbon assessments, or time change series.