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The occurrence frequency of regional atmospheric new aerosol particle formation and consecutive growth events (fNPF) were studied with respect to vegetation activity, aerosol properties, air pollutants and meteorological data in Budapest over the time interval from 2008 to 2018. The data set evaluated contained results of in situ measurements on the land surface that were mostly performed at the Budapest platform for Aerosol Research and Training Laboratory, of satellite-based products recorded by MODIS on Terra and of modelled vegetation emission-related properties from an advanced regional biogeochemical model. The annual mean relative occurrence frequencies were considerable (with an overall mean of 21 %), remained at a constant level (with an overall SD of 5 %) and did not exhibit tendentious change over the years. The shape of the distributions of monthly mean fNPF exhibited large variability from year to year, while the overall average distribution already possessed a characteristic pattern. The structure of the new particle formation (NPF) occurrence distributions was compared to those of environmental variables including concentrations of gas-phase H2SO4, SO2, O3, NO, NO2, CO, PM10 mass and NH3; particle numbers in the size fractions of 6–1000, 6–100 and 100–1000 nm; condensation sink; air temperature (T); relative humidity (RH); wind speed (WS); atmospheric pressure (P); global solar radiation (GRad); gross primary production (GPP) of vegetation; leaf area index (LAI); and stomatal conductance (SCT). There were no evident systematic similarities between fNPF on the one hand and all of the variables studied on the other hand, except for H2SO4 and perhaps NH3. The spring maximum in the NPF occurrence frequency distribution often overlapped with the time intervals of positive T anomaly in vegetated territories. The link between the potential heat stress exerted on plants in sultry summer intervals and the summer fNPF minimum could not be proven. The relevance of environmental variables was assessed by their ratios on NPF event days and on non-event days. The gas-phase H2SO4 concentration showed the largest monthly ratios, followed by O3. The WS, biogenic precursor gases and SO2 can generally favour NPF events, although their influence seemed to be constrained. An association between the fNPF and vegetation growth dynamics was clearly identified.

Sulfuric acid has been shown to be a key driver for new particle formation and subsequent growth in various environments, mainly due to its low volatility. However, direct measurements of gas-phase sulfuric acid are oftentimes not available, and the current sulfuric acid proxies cannot predict, for example, its nighttime concentrations or result in significant discrepancies with measured values. Here, we define the sources and sinks of sulfuric acid in different environments and derive a new physical proxy for sulfuric acid to be utilized in locations and during periods when it is not measured. We used H2SO4 measurements from four different locations: Hyytiälä, Finland; Agia Marina, Cyprus; Budapest, Hungary; and Beijing, China, representing semi-pristine boreal forest, rural environment in the Mediterranean area, urban environment and heavily polluted megacity, respectively. The new proxy takes into account the formation of sulfuric acid from SO2 via OH oxidation and other oxidation pathways, specifically via stabilized Criegee intermediates. The sulfuric acid sinks included in the proxy are its condensation sink (CS) and atmospheric clustering starting from H2SO4 dimer formation. Indeed, we found that the observed sulfuric acid concentration can be explained by the proposed sources and sinks with similar coefficients in the four contrasting environments where we have tested it. Thus, the new proxy is a more flexible and an important improvement over previous proxies. Following the recommendations in this paper, a proxy for a specific location can be derived.

Community participation in the conservation of tropical fruit trees is one approach taken by the Tropical Fruit Trees Project funded by UNEP/GEF carried out at six sites in Malaysia. Three conservation approaches were implemented at the sites that are diversity block, heritage block and common block. A total of 1550 fruit trees mainly from the genera Mangifera, Garcinia and Nephelium were planted. At Kampung Kakeng, Serian, Sarawak a 5 ha diversity block was established. 110 fruit trees comprising species from the genera Mangifera, Nephelium, Garcinia, Durio, Artocarpus, Anonna, and Musa were planted in the diveristy block. An orchard consisting of many species of old fruit trees at Sibuti was identified as a Heritage Block for conservation and education purposes. A Mangifera pentandra tree aged more than 100 years from the Heritage Block was used as a source of seeds for new plantings. While in Kota Belud, a few binjai (Mangifera caesia) trees 50 - 100 years old were labelled as heritage fruit trees for public awareness as well as for conservation in the Heritage block. At other sites Yan, Papar and Bukit Gantang, fruit trees within the genus Mangifera, Garcinia and Nephelium were planted in the homegardens, orchards and public places such as playground compounds or near riversides.

Tropical regions are rich in fruit diversity and many globally important tropical fruit tree species and their wild relatives, including the rare or neglected species, are of Asian origin. Conservation of these tropical fruit species is imperative as they are increasingly threatened. For cultivated species the threat is by specialization of production systems restricted to a few varieties and by land use changes, and in the case of wild relatives it is due to habitat loss. Conservation efforts are in progress by various countries and agencies in order to save the rich tropical fruit diversity. Conservation methods include in situ and ex situ (field genebanks, botanical gardens, in vitro and cryopreservation). As the main objective of genetic resource conservation is for utilization in crop improvement, characterization and evaluation of all the accessions are carried out together with the collection and conservation efforts. In this chapter, conservation efforts of tropical fruit species will be covered for the whole tropical region in general and emphasis will be given to three main areas; Malaysia, South Asia (India), and tropical Africa, occasionally touching tropical America. Challenges and future directions are discussed.