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1.
Oil palm plantations today cover large areas of former tropical lowland rain forest in Southeast Asia and are rapidly expanding on the island of Borneo. Study of the community of ground-dwelling ants in different plantations in Sabah, Malaysia, over 2 years using tuna baiting, revealed that the oil palm plantation ground ant community was severely reduced in species richness in comparison to the forest interior, regardless of age, undergrowth cover, or proximity to neighbouring forest. The results indicate that oil palm plantation habitats, now covering more than 15% of Sabah’s land area, can sustain only about 5% of the ground-dwelling ant species of the forest interior. Nine of the 23 ant species baited in the plantations were never recorded inside forest. All numerically dominant ants were non-forest species. The most common species was Anoplolepis gracilipes, an invasive species present at 70% of all bait sites and known to cause ‘ecological meltdowns’ in other situations. The low frequency and species number of forest ground ants indicates that oil palm plantations act as effective dispersal barriers leading to community isolation in rain forest remnants. The replacement of natural forests with oil palm plantations poses a serious threat to the conservation of biodiversity on Borneo if similar results are confirmed in other taxa.  相似文献   

2.
Throughout the world, previously extensive areas of natural habitats have been degraded and fragmented, and improving habitat connectivity may help the long-term persistence of species, and their ability to adapt to climate changes. We focused on Borneo, where many remaining areas of tropical forest are highly fragmented, and we assessed the extent to which Protected Areas (PAs) protect highly-connected forest sites. We analysed remotely-sensed land cover data (0.86 km2 grid cell resolution) using ‘Zonation’ reserve design software, and we ranked grid cells (rank 0–1) according to forest extent and connectivity. PAs currently cover 9% of Borneo, but <20% of highly-connected cells (i.e. cells with Zonation ranks ≥0.9) lie within PAs. Approximately 65% of highly-connected cells were located above 400 m elevation, although >60% of Borneo’s total land area lies below 200 m and only 15% of highly-connected cells occurred in these low elevation areas. These findings were relatively insensitive to assumptions about species’ dispersal ability (within the range 1–20 km; representing relatively mobile animal species). The percentage of highly-connected grid cells within PAs could rise from <20 to >50% under proposed new PAs (including the ‘Heart of Borneo’ project), although many other highly-connected sites will remain unprotected. On-going land-use changes mean that existing PAs in lowland areas are likely to become increasingly isolated within inhospitable agricultural landscapes, and improving connectivity through reforestation and rehabilitation of degraded forest may be required to maintain the conservation value of these PAs in future.  相似文献   

3.
Bird communities of natural and modified habitats in Panama   总被引:7,自引:0,他引:7  
Only a small proportion of land can realistically be protected as nature reserves and thus conservation efforts also must focus on the ecological value of agroecosystems and developed areas surrounding nature reserves. In this study, avian communities were surveyed in 11 habitat types in central Panama, across a gradient from extensive forest to intensive agricultural land uses, to examine patterns of species richness and abundance and community composition. Wooded habitats, including extensive and fragmented forests, shade coffee plantations, and residential areas supported the most species and individuals. Nearctic-Neotropical migratory species were most numerous in lowland forest fragments, shade coffee, and residential areas. Introduced Pinus caribbea and sugar cane plantations supported the fewest species compared to all other habitats. Cattle pastures left fallow for less than two years supported more than twice as many total species as actively grazed pastures, such that species richness in fallow pastures was similar to that found in wooded habitats. Community similarities were relatively low among all habitat types (none exceeding the observed 65% similarity between extensive and fragmented lowland forests), but communities in shade coffee and residential areas were 43% and 54′% similar to lowland forest fragments, respectively. Fallow pastures and residential areas shared 60% of their species. Bird communities in shade coffee and residential areas were characterized by higher proportions of frugivorous and nectarivorous species than in native forests. These same guilds also were better represented in fallow than in grazed pastures. Raptors and piscivorous species were most prevalent in cattle pastures and rice fields. These results, though based upon only species richness and abundance, demonstrate that many human-altered habitats have potential ecological value for birds, and conservation efforts in tropical areas should focus greater attention on enhancement of agricultural and developed lands as wildlife habitat. To understand the true conservation value of these modified lands will require examination not only of numbers but also of the types of species supported by these habitats, their reproductive output and survival rates.  相似文献   

4.
Plantation forests and biodiversity: oxymoron or opportunity?   总被引:3,自引:1,他引:2  
Losses of natural and semi-natural forests, mostly to agriculture, are a significant concern for biodiversity. Against this trend, the area of intensively managed plantation forests increases, and there is much debate about the implications for biodiversity. We provide a comprehensive review of the function of plantation forests as habitat compared with other land cover, examine the effects on biodiversity at the landscape scale, and synthesise context-specific effects of plantation forestry on biodiversity. Natural forests are usually more suitable as habitat for a wider range of native forest species than plantation forests but there is abundant evidence that plantation forests can provide valuable habitat, even for some threatened and endangered species, and may contribute to the conservation of biodiversity by various mechanisms. In landscapes where forest is the natural land cover, plantation forests may represent a low-contrast matrix, and afforestation of agricultural land can assist conservation by providing complementary forest habitat, buffering edge effects, and increasing connectivity. In contrast, conversion of natural forests and afforestation of natural non-forest land is detrimental. However, regional deforestation pressure for agricultural development may render plantation forestry a ‘lesser evil’ if forest managers protect indigenous vegetation remnants. We provide numerous context-specific examples and case studies to assist impact assessments of plantation forestry, and we offer a range of management recommendations. This paper also serves as an introduction and background paper to this special issue on the effects of plantation forests on biodiversity.
Eckehard G. BrockerhoffEmail:
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5.
In view of the extensive destruction, fragmentation, and conversion of primate habitats to anthropogenic vegetation, information on Neotropical primate ability to use a landscape consisting of forest fragments and agricultural habitats is necessary to understand the ecological flexibility of the species involved and it is of relevance to the design of conservation scenarios at the landscape level. We censused howlers and spider monkeys in 126 forest fragments and in 44 agricultural sites at Los Tuxtlas, southern Veracruz, Mexico, and used the IDRISI Geographic Information System to assess the extent of primate habitat remaining. We conducted economic surveys to assess the productivity of several systems of land management, including cattle ranching. Seventy- five percent of native habitat has been lost at Los Tuxtlas, 20% remains in the form of isolated fragments of vegetation, and only 5% consists of contiguous rain forest at high elevations (> 800 m). Howlers and spider monkeys were present in only 60 and 8% of the forest sites investigated, respectively, attesting to extensive local extinction. Populations of both species are small and found in a fragmented and isolated condition throughout the landscape. A large number of howlers were detected in artifactual habitats such as cacao, coffee and mixed (cacao and coffee) plantations shaded by rain forest trees. Residual rain forest vegetation along streams, rivers, and lakes facilitated the interfragment and interhabitat movement of howlers. Economic surveys showed that some of the agricultural habitats were more productive than cattle ranching. Conservation of spider monkeys requires large areas of contiguous forest, but only small areas are present at high elevations. Howlers are restricted to elevations < 800 m, where most of the forest has disappeared, but can apparently exist in a matrix of forest fragments, arboreal agricultural habitats, and pasture lands. Structural aspects of the vegetation and connectivity among habitat islands may be indispensable components of both landscape scenarios.  相似文献   

6.
In the current deforestation context, agroforestry is increasingly considered in the tropical zone for its potential contribution to biodiversity conservation. In Guinée Forestière (Guinea, West Africa), coffee-based species rich agroforests are currently expanding on agricultural land around most villages. To assess the role these agroforests play with respect to biodiversity conservation, we compared their tree structure and diversity with those of a neighbouring natural forest. Eighty plots were sampled using a variable area transect method (60 plots distributed into 3 village agroforests, 20 natural forest plots). The structure of coffee-based agroforests showed obvious signs of farmers’ management: density of mature trees was significantly lower than in natural forest and most juvenile trees were eliminated and replaced by coffee trees. However, tree seedling density was not significantly different than in natural forest. Tree species richness and diversity were also lower than in natural forest but much higher than in any other agricultural or agroforestry land use system. These results are close to those obtained in the coffee-based agroforests of Central America, confirming that coffee-based agroforests retain many forest species that play a key role in the conservation of regional forest tree diversity.  相似文献   

7.
Khawa Karpo, in the eastern Himalayas, is a mountain considered sacred throughout Tibet, and is internationally recognized as a global biodiversity hotspot. Numerous areas within this landscape are considered ‘sacred’ by the indigenous Tibetans of the region, who interact with these sites in ways potentially beneficial to conservation. Our previous remote sensing study indicated that sacred sites are found in habitats with greater species richness, diversity, and endemism than randomly selected non-sacred sites. This study examines the role of sanctity in biodiversity conservation within habitats in the Khawa Karpo region by pairing plots within the same habitats in sacred and non-sacred areas. Understory richness, diversity, cover, and number of useful species are measured; for trees, richness, diversity, cover, and density are measured. Results indicate that within habitats sanctity does not affect understory plant communities; however, within sacred areas trees are larger (p = 0.003) and forests have greater cover (p = 0.003) than non-sacred areas. Our results indicate that, whereas placement of sacred areas and preservation of vegetation cover affects useful plants, biodiversity and endemism, within habitats sacred sites preserve old growth trees and forest structure. In sum, Tibetan sacred sites are ecologically unique and important for conservation on varying scales of landscape, community, and species.  相似文献   

8.
Agricultural intensification typically leads to changes in bird diversity and community composition, with fewer species and foraging guilds present in more intensively managed parts of the landscape. In this study, we compare bird communities in small (2–32 ha) brigalow (Acacia harpophylla) remnants with those in adjacent uncultivated grassland, previously cultivated grassland and current cropland, to determine the contribution of different land uses to bird diversity in the agricultural landscape. Twenty remnant brigalow patches and adjacent agricultural (‘matrix’) areas in southern inland Queensland, Australia were sampled for bird composition and habitat characteristics. The richness, abundance and diversity of birds were all significantly higher in brigalow remnants than in the adjacent matrix of cropping and grassland. Within the matrix, species richness and diversity were higher in uncultivated grasslands than in current cultivation or previously cultivated grasslands. Forty-four percent of bird species were recorded only in brigalow remnants and 78% of species were recorded in brigalow and at least one other land management category. Despite high levels of landscape fragmentation and modification, small patches of remnant brigalow vegetation provide important habitat for a unique and diverse assemblage of native birds. The less intensively managed components of the agricultural matrix also support diverse bird assemblages and thus, may be important for local and regional biodiversity conservation.  相似文献   

9.
In northern Europe, a long history of land use has led to profound changes within forest ecosystems. The white-backed woodpecker (Dendrocopos leucotos) is one of several specialised forest species whose populations have declined. Conservation management directed at this species’ habitat has made it a de facto umbrella species for conservation of the biodiversity associated with forests rich in deciduous trees and dead wood. We assessed empirically the value of the white-backed woodpecker as an indicator and umbrella species in central Sweden. Occurrence of the woodpecker in breeding bird atlas squares (5 × 5 km2) indicated high species richness of forest birds, particularly species of special conservation concern, which included on average 13% more species in squares with than without the woodpecker. The number of red-listed cryptogam species expected to benefit from conservation actions directed at white-backed woodpecker habitats was higher in squares where the woodpecker bred compared to where is was absent. However, no such pattern was found for red-listed beetles, a group with very few records in the studied squares. White-backed woodpecker occurrence was positively associated with the current area of deciduous and mixed forest of high conservation value. Considering its indicator value, its specialised habitat requirements and its potential as a communication tool, using the white-backed woodpecker as an umbrella species may provide a coarse filter for the conservation of several other deciduous forest species. However, focusing solely on white-backed woodpecker habitat may not provide for the conservation of all such species, which stresses the need for a suite of complementary planning approaches.  相似文献   

10.
Land use change and human population growth are accelerating the fragmentation and insularization of wildlife habitats worldwide. The conservation and management of wildlife in the resultant ‘island’ ecosystems in the context of global warming is challenging due to the isolation and reduced size of the ecosystems and hence the scale over which ecosystem processes can operate. We analyzed trends in numbers of nine large herbivores in Kenya’s Lake Nakuru National Park to understand how rainfall and temperature variability, surrounding land use changes, and boundary fencing affected wildlife population dynamics inside the park during 1970–2011. Buffalo, zebra and Thomson’s gazelle numbers increased persistently. Grant’s gazelle and impala increased initially then gradually declined. Waterbuck and warthog numbers progressively declined to levels that potentially threatened their local population persistence. The total biomass of ungulates tripled from 1970 to 2011, with buffalo replacing waterbuck as the predominant species in biomass. Increased competition from buffalo and zebra, heightened predation and illicit human harvests probably all contributed to the declines by waterbuck and warthog. Density-dependent limitation of population growth within the park confines was evident for buffalo, impala, eland, giraffe, Grant’s and Thomson’s gazelles. Fluctuations in the lake level related to varying rainfall affected changes in animal abundance through expansion of the lake area and flooding of grasslands bordering the lake. Unusually, the most stressful conditions were associated with high water levels following high rainfall. There was also evidence of carry-over effects from prior habitat conditions affecting all species. The relatively stable populations of all species except warthog and waterbuck demonstrate the remarkable capacity of this small, insularized park to retain viable populations of most of the large herbivores, without much management intervention.  相似文献   

11.
Fossil pollen and plant macrofossils over the last 2000 years are documented from three small forest hollows in Southern Sweden. One of the sites is inside a 5 ha highly prized old growth mixed Fagus sylvatica and Picea abies forest of high biodiversity which has been protected since 1940. The other two hollows are located 400 and 700 m away in an outlying buffer zone established in 1995 which is mainly coniferous plantation forest. The results show that the area has been forested for at least 2000 years, but that forest composition has been under continuous change, most rapid over the last 200 years. The reduction of deciduous tree pollen particularly Quercus, Tilia, Alnus and Corylus, and the immigration of Fagus and Picea can be observed at all three sites. However, the temperate deciduous trees (Quercus or Fagus) have been much more common in the ‘hotspot’ than in the surrounding forests over the last c. 200 years, and significantly more common at least 2000 years before that. Even though the vegetation has been dynamic through time, the lower human intervention in the ‘hotspot’ area compared with the surrounding matrix forests has facilitated the longevity of deciduous trees and the many rare species which are associated with them. The palaeoecological record of key species and information on past use of the wider forest area revealed in this study, indicates how future management will require flexibility to maintain conservation ‘hotspots’.  相似文献   

12.
Agricultural activities represent a global threat to biodiversity, yet little is known about the relative importance of different agricultural land uses in relation to their wildlife communities. We explored bird community structure, diversity, and composition in a landscape dominated by primary tropical dry forest, and in three agricultural systems (i.e., tree orchards, herbaceous cropfields, cattle pastures) to evaluate the way in which birds use different habitats within the landscape. Tropical dry forests had the highest species richness and community evenness, although the bird community in tree orchards was also relatively species rich and even. Cattle pastures had more bird species than cropfields but both habitats were comparatively species poor with low evenness. Our results are related to habitat structure and the spatial location of sites within the landscape matrix. Based on our observations, we recommend including native tree species within agricultural systems and surrounding areas to provide additional resources for birds. Finally, we suggest promoting natural recruitment of native trees and shrubs within cattle pastures to provide suitable habitat for species that use tropical dry forest plants. Abstract in Spanish is available at http://www.blackwell‐synergy.com/loi/btp .  相似文献   

13.
We carried out a survey on roadside dark-bellied bonnet macaques (Macaca radiata radiata) on the highways around the south Indian city of Mysore. The present survey was the fourth since 1989 on the same populations. We divided the habitats into intensive cultivation (IC), wet cultivation (WC), and scrub forests (SC). The number of groups has significantly reduced from 54 to 31 and the number of animals has declined from 1,207 to 697 from 1989 to 2009. This decline has been recorded only in the IC and WC areas, whereas the population in SC with places of Hindu worship has remained stable. Due to the loss of roadside Ficus trees over the years, the habitat of the monkeys has almost disappeared. Since bonnet macaque is not primarily a forest-dwelling species, the seemingly widespread primate may soon become ‘threatened’ if the non-forest populations continue to decline. Scrub forests in small hillocks housing Hindu temples remain the only prospective places for conservation of bonnet macaques.  相似文献   

14.
Wildfires are an increasing threat to tropical rainforests, yet little is known about their effects on fruit production and forest wildlife. We examined the effects of both single and recurrent wildfires on fruit production and large vertebrate abundance in a central Amazonian terra firme forest for 3 years following a large fire event. The estimated mortality of 42 and 74% of stems ≥10 cm in once- and twice-burnt forest led to a substantial loss of fruiting tree basal area (29 and 62% were lost in once- and twice-burnt forest, respectively) and crown coverage of fruiting woody lianas (89 and 97% were lost in once- and twice-burnt forest, respectively). Some important tree families producing fleshy fruits were less abundant than expected in once- and twice-burnt forest, suggesting that tree mortality was non-random in terms of species composition. Asynchronous fruit production was affected, and burnt forest transects sustained a much lower fruiting basal area, and fewer fruiting species during the dry season period of fruit scarcity. The number of fruiting trees in once- and twice-burnt forest was higher than the number predicted from actual levels of tree mortality recorded in each fire disturbance treatment, suggesting some surviving trees which may have benefited from higher irradiance levels and lower competition for resources. Many large frugivores and other vertebrate species declined in response to single fires, and most primary forest specialists were extirpated from twice-burnt forest, which sustained a higher number of species associated with second growth and other disturbed habitats.  相似文献   

15.
Amazonian white-water (várzea) floodplains harbor many commercially important timber species which in Brazil are harvested following regulations of the Federal Environmental Agency (IBAMA). Although it is well-known that tree physiology, growth, and species distribution of Amazonian floodplain trees is linked to the heights and durations of the periodical inundations, information about timber stocks and population dynamics is lacking for most tree species. We investigated timber stocks and the population structure of four intensely logged tree species in a western Brazilian várzea forest on an area totaling 7.5 ha. Spatial distribution was investigated in all trees as a function of inundation height and duration and the distance to the river channel, and additionally for saplings (trees <10 cm diameter at breast height––DBH) as a function of the relative photosynthetically active radiation (rPAR). The diameter-class distribution in Hura crepitans and Ocotea cymbarum indicated that populations are subject to density variations that possibly are traced to small-scale flood variability. In all species, saplings concentrated at higher topographic elevations than the mature tree populations, which suggest that the physical ‘escape’ from a flooded environment is an important acclimation to flooding. While Ocotea cymbarum and Guarea guidonia were high-density wood species characterized by random dispersion and a pronounced shade-tolerance, Hura crepitans and Sterculia apetala presented lower wood density, aggregated dispersion, and were more light-demanding. All species presented exploitable stems according to the current harvest regulations, with elevated abundances in comparison to other Amazonian forest types. However, stem densities are below the harvest rates indicating that the harvest regulations are not sustainable. We recommend that the forest management in várzea forests should include specific establishment rates of timber species in dependence of the peculiar site conditions to achieve sustainability.  相似文献   

16.
Understanding the historical biogeography of this global biodiversity hotspot is as important to long-term conservation goals as ecology and evolution are to understanding current patterns and processes. Today’s geography is, however, misleading and typical of only ~2% of the last million years; >90% of that time the region’s land area was 1.5–2.0 times larger as mean sea levels were 62 m below today’s, climates were cooler, and extensive forests and savanna covered the emerged Sunda plains. The region’s land area varied two-fold as sea levels fluctuated up to ±50 m with each of ~50 Pleistocene glacial cycles, and forests expanded and contracted with oscillations in land area and seasonality. This dynamic geographic history is relevant to the development of biogeographic regionalism and shows that it is today’s forests that are refugial, not those of the Last Glacial Maximum. This history affects how species will adapt or shift their ranges in response to global warming and further decreases in land area (submergence of low-lying coastal areas) during the 21st century. The alternative is mass species extinction. The biota is also threatened by the continued destruction of forest, destruction of Mekong River flood-pulse based ecosystems, and continued human population growth. Human biogeography will become more important in conservation planning as tens of millions of people who depend on protected area forests, riverine ecosystems, and coastal habitats become environmental refugees. Conservation scientists need to become more involved in regional ecological education, environmental stewardship, and ecosystem-based adaptation to sustain as much as possible of this rich biota and the ecological services it provides.  相似文献   

17.
Nowadays 37% of Earth’s ice-free land is composed by fragments of natural habitats settled in anthropogenic biomes. Therefore, we have to improve our knowledge about distribution of organisms in remnants and to understand how the matrix affects these distributions. In this way, the present study aims to describe the structure of the butterfly assemblages and determined how richness and abundance are influenced by the scale of the surrounding vegetation. General linear models were used to investigate how the type and scale of vegetation cover within a radius of 100–2,000 m around the sampling point explained butterfly diversity. After sampling ten forest fragments we found 6,488 individuals of 73 species. For all clades tested null models explain the species richness at the fragments better than other models when we include the effect of butterfly abundance as a covariate. Abundance of Satyrini, Brassolini, and Biblidinae were best predicted by small scales (100–200 m), and large scales were more suited for Charaxinae. The presence of pasture best explains the abundance of all groups except Charaxinae, which was best explained by early-regrowth forest. The abundance of different species and groups are correlated with different kinds of vegetation cover. However, we demonstrate that small scales (100–200 m) are more effective at explaining the abundance of most butterflies. These results strongly suggest that efforts to preserve insect diversity in forest fragments should take in account the immediate surroundings of the fragment, and not only the regional landscape as a whole. In general, actions of people living near forest fragments are as important to fruit-feeding butterflies as large scale actions are, with the former being seldom specified in management plans or conservation policies.  相似文献   

18.
Clearance of tropical forest for agricultural purposes is generally assumed to seriously threaten the survival of forest species. In this study, we quantified the conservation value, for forest bird species, of three degraded habitat types in Peninsular Malaysia, namely rubber tree plantations, oil palm plantations, and open areas. We surveyed these degraded habitats using point counts to estimate their forest bird species richness and abundance. We assessed whether richness, abundance, and activities of different avian dietary groups (i.e. insectivores and frugivores) varied among the habitats. We identified the critical habitat elements that accounted for the distribution of forest avifauna in these degraded habitats. Our results showed that these habitats harboured a moderate fraction of forest avifauna (approximately 46–76 species) and their functions were complementary (i.e. rubber tree plantations for moving; open habitats for perching; shrubs in oil palm plantations for foraging). In terms of species richness and abundance, rubber tree plantations were more important than oil palm plantations and open habitats. The relatively high species richness of this agricultural landscape was partly due to the contiguity of our study areas with extensive forest areas. Forecasts of forest-species presence under various canopy cover scenarios suggest that leaving isolated trees among non-arboreal crops could greatly attract relatively tolerant species that require tree canopy. The conservation value of degraded habitats in agricultural landscapes seems to depend on factors such as the type of crops planted and distance to primary forest remnants.  相似文献   

19.
Biogeographical studies are a necessary step in establishing conservation area networks. Determining the ecological factors influencing vegetation is also a basic principle for hierarchical ecological classifications and a necessary prerequisite for ecosystem-based land use planning. Eco-floristic sectors (EFS) have already been identified for the Indonesian island of Sumatra, combining both approaches, dividing it into 38 EFSs representing unique ecosystems in terms of tree flora and environment (Laumonier 1997). The impact of deforestation on individual EFSs has been highly varied and in some cases extreme. We assigned one of five ‘extinction risk categories’ to each EFS based on the percentage of forest lost between 1985 and 2007. Eighty-five percent of all forest loss (10.2 million ha) occurred in the eastern peneplain, western lowland regions and swamps. In 2007, only 29% of forests were protected by conservation areas, only nine of the 38 EFS had more than 50% of their remaining forest cover protected. 38% of remaining forest was “critically endangered”, “endangered” or “vulnerable” EFSs (5 million ha) but only 1 million ha (20%) were protected. Sumatra’s existing network of conservation areas does not adequately represent the island’s ecosystems. Priorities for a new conservation area network can be formulated for integration into Sumatra’s new land use plans at provincial and district level. Decision makers can now use EFSs to locate new conservation areas so they represent and maintain the whole range of the island’s diversity.  相似文献   

20.
The influence of alternate bearing on nutrient utilization and total tree nutrient content was investigated in mature pistachio (Pistacia vera L. cv Kerman trees). Removal of N, P and Zn in fruit and abscised leaves of cropping (‘on’) trees averaged 5, 6, and 2 times, respectively, the removal in abscised leaflets of the non-fruiting, ‘off’ year trees. One hundred and thirty-five kg N, 131 kg K, 86 kg Ca, 39 kg Mg and 18 kg P per hectare were removed in fruits and abscised leaves in ‘on’ year trees. Tree nutrient contents and, presumably, the size of nutrient storage pools in dormant trees varied between ‘on’ and ‘off’ years. There was 22% and 14% more N and P, respectively, in dormant trees following ‘off’ than ‘on’ years. The greater N and P accumulation in ‘off’ year trees is depleted in support of the large fruit demand for N and P during ‘on’ years. In contrast to N and P, there was greater K and Ca accumulation in perennial tree parts during ‘on’ years than during ‘off’ years. The greater K accumulation in perennial tree parts and approximately 30% greater removal of K in annual organs during ‘on’ than ‘off’ years suggests that K uptake could be 4 times higher in ‘on’ year trees than in (non-cropping), ‘off’ year trees.  相似文献   

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