indeks kelestarian lingkungan-biodiversitas
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INDEKS KELESTARIAN LINGKUNGAN
=Environmental
Sustainability Index
Diabstraksikan oleh: soemarno, psdl ppsub, desember 2012
Bahan Kajian pada MK. PSDAL
BIODIVERSITAS
BIODIVERSITY = KEANEKA RAGAMAN HAYATI
Diunduh dari: http://woentari-monica.blogspot.com/2012/05/pengertian-keanekaragaman-hayati-dari.html……………… 4/12/2012
1. Keragaman hayati (biodiversity atau biological diversity) merupakan istilah yang digunakan untuk menggambarkan kekayaan berbagai bentuk kehidupan di bumi ini mulai dari organisme bersel tunggal sampai organisme tingkat tinggi. Keragaman hayati mencakup keragaman habitat, keragaman spesies (jenis) dan keragaman genetik (variasi sifat dalam spesies)
2. Keanekaragaman Hayati adalah tingkat variasi bentuk kehidupan dalam suatu ekosistem tertentu, bioma, atau seluruh planet. Keanekaragaman Hayati adalah ukuran dari kesehatan ekosistem. Keanekaragaman Hayati adalah sebagian fungsi dari iklim. Pada habitat darat, daerah tropis biasanya kaya sedangkan daerah-daerah kutub dukungan spesies yang lebih sedikit. Perubahan lingkungan yang cepat biasanya menyebabkan kepunahan massa. Salah satu perkiraan adalah bahwa kurang dari 1% dari spesies yang telah ada di Bumi yang masih ada.
3. Keanekaragaman Hayati adalah keseluruhan variasi berupa bentuk, penampilan, jumlah, dan sifat yang dapat ditemukan pada makhluk hidup.Keanekaragaman hayati merupakan lahan penelitian dan pengembangan ilmu yang sangat berguna untuk kehidupan manusia.
KEANEKARAGAMAN HAYATI
Diunduh dari: http://staff.blog.ui.ac.id/andreas.pramudianto/2009/02/27/keanekaragaman-hayati-dalam-hukum-lingkungan-internasional/ ……………… 4/12/2012
Keanekaragaman hayati menekankan pada semua jenis spesies tumbuhan, hewan dan mikroorganisme juga dengan ekosistimnya dimana mereka merupakan bagian yang tak terpisahkan, termasuk jumlah dan frekuensi ekosistem,
spesies dan gen yang saling berkaitan.
Ada tiga macam keanekaragaman hayati, yaitu :
a. Keanekaragaman spesies (Species Diversity)b. Keanekaragaman ekosistem (Ecosystem Diversity)c. Keanekaragaman genetika (Genetic Diversity)
Keanekaragaman spesies / jenis (Species Diversity)Keanekaragaman spesies terbentuk
oleh adanya kesesuaian
kandungan genetika yang mengatur sifat
dari kebakaan dengan lingkungan terhadap anggota
jenis yang sama yang dalam hal ini
memiliki kerangka dasar, komponen
genetika khususnya kromosom yang
sama.Diunduh dari: http://staff.blog.ui.ac.id/andreas.pramudianto/2009/02/27/keanekaragaman-hayati-dalam-hukum-
lingkungan-internasional/ ……………… 4/12/2012
Species Richness Index: Simpson’s Index
Simpson gave the probability of any two individuals drawn at random from an infinitely large community
belonging to different species. The Simpson index is therefore expressed as 1-D or
1/D.
Simpson’s index is heavily weighed towards the most abundant species in the sample while being
less sensitive to species richness. It has been shown that once the number of species exceeds 10 the
underlying species abundance distribution is important in determining whether the index has a
high or low value. The D value which is standing for the dominance
index is used in pollution monitoring studies. As D increases, diversity decreases.
(diunduh dari: http://webcache.googleusercontent.com/search?q=cache:CN372gBQkCwJ:ocw.unu.edu/)
Species Diversity Indices: Shannon-Wiener Index
Shannon and Wiener independently derived the function which has become known as Shannon index of diversity. This indeed assumes that
individuals are randomly sampled from an independently large population.
The index also assumes that all the species are represented in the sample. Log2 is often used for calculating this diversity index but any log base
may be used. It is of course essential to be consistent in the choice of log base when comparing diversity between samples or estimating evenness.
The value of Shannon diversity is usually found to fall between 1.5 and 3.5 and only rarely it surpasses 4.5. It has been reported that under log
normal distribution, 105 specieswillbe needed to produce a value of Shannon diversity more than 5. Expected Shannon diversity is also used (Exp H’) as an alternative to H’. Exp H’ is equivalent to the number of
equally common species required to produce the value of H’ given by the sample.
The observed diversity (H’) is always compared with maximum Shannon diversity (Hmax) which could possibly occur in a situation where all
species were equally Abundant.Diunduh dari: http://staff.blog.ui.ac.id/andreas.pramudianto/2009/02/27/keanekaragaman-hayati-dalam-hukum-
lingkungan-internasional/ ……………… 4/12/2012
Keanekaragaman ekosistem (Ecosystem Diversity)
Merupakan suatu kesatuan lingkungan
yang melibatkan unsur-unsur biotik, faktor fisik
(iklim, tanah dan air) dan faktor kimia
(keasaman) yang saling berinteraksi.
Beberapa tipe (kelompok) keanekaragaman ekosistem antara lain :1. Ekosistem bahari:
Terdiri dari ekosistem laut dan ekosistem pantai
2. Ekosistem darat”: Terdiri dari vegetasi dataran rendah, vegetasi pegunungan dan vegetasi munson.
Diunduh dari: http://staff.blog.ui.ac.id/andreas.pramudianto/2009/02/27/keanekaragaman-hayati-dalam-hukum-lingkungan-internasional/ ……………… 4/12/2012
An ecosystem is a community plus the physical environment that it occupies at a given time. An
ecosystem can exist at any scale, for example, from the size of a small tide pool up to the size of the entire biosphere. However, lakes, marshes, and forest stands represent more typical examples of
the areas that are compared in discussions of ecosystem diversity.
The diversity of an ecosystem is dependent on the physical characteristics of the environment, the diversity of species present, and the interactions
that the species have with each other and with the environment. Therefore, the functional complexity of an ecosystem can be expected to increase with the
number and taxonomic diversity of the species present, and the vertical and horizontal complexity
of the physical environment.
(Sumber: http://cnx.org/content/m12156/latest/#roth)
KEANEKARAGAMAN GENETIKA (GENETIC DIVERSITY)
Setiap kerangka dasar komponen
genetika tersusun ribuan faktor
kebakaan keturunan.
Satu faktor pengatur kebakaan disebut gen, suatu lingkungan yang
memuat tumbuhan yang liar/sudah didomestikasi.
Diunduh dari: http://staff.blog.ui.ac.id/andreas.pramudianto/2009/02/27/keanekaragaman-hayati-dalam-hukum-lingkungan-internasional/ ……………… 4/12/2012
Keanekaragaman genetik (genetic diversity) adalah suatu tingkatan biodiversitas yang merujuk
pada jumlah total variasi genetik dalam keseluruhan spesies yang mendiami sebagian atau seluruh
permukaan bumi yang dapat didiami. Ia berbeda dari variabilitas genetik, yang menjelaskan kecenderungan kemampuan suatu karakter/sifat untuk bervariasi yang
dikendalikan secara genetik.
Pengukuran keanekaragaman genetikKeanekaragaman genetika suatu populasi dapat diperkirakan dengan menggunakan beberapa
pengukuran sederhana.
1. Keanekaragaman gen, adalah proporsi lokus polimorfik diseluruh genom.
2. Heterozigositas, adalah jumlah rata-rata individu dengan lokus polimorfik.
3. Alel per lokus, juga digunakan untuk mendemonstrasikan variabilitas.
(sumber: http://id.wikipedia.org/wiki/Keanekaragaman_genetik)
BiodiversityVariety of living things, number of
kinds
Ecological diversitydifferent habitats, niches, species
interactionsSpecies diversity
different kinds of organisms, relationships among species
Genetic diversitydifferent genes & combinations of
genes within populations
Diunduh dari: facstaff.gpc.edu/~apennima/ENVS/Biodiversity.ppt
Manfaat Biodiversitas
• Fungsi ekosistem• Jasa-jasa Ekosistem
• Membersihkan air,• Cleaning air,• Habitat & breeding areas for wildlife, …
• Manfaat estetika dan budaya
Diunduh dari: facstaff.gpc.edu/~apennima/ENVS/Biodiversity.ppt
• Vital economic natural resources– Renewable
• Forests (plants, wildlife) • Soils • Fresh water (lakes, rivers)• Wildlife and fisheries• Rangeland
– Nonrenewable• Minerals • Fossil Fuels
Diunduh dari: facstaff.gpc.edu/~apennima/ENVS/Biodiversity.ppt
Sumberdaya Alam
Sumberdaya Alam• Management of natural
resources– Assure availability of
resources for the future– Three “philosophies”
• Maximum sustained yield• Ecosystem-based
management • Adaptive management
Diunduh dari: facstaff.gpc.edu/~apennima/ENVS/Biodiversity.ppt
• New food sources– Grains, fruits, vegetables, meat, fish
Diunduh dari: facstaff.gpc.edu/~apennima/ENVS/Biodiversity.ppt
Manfaat Biodiversitas
Pengobatan:• Plants• Jellyfish & sea
anemones• Nudibranchs
• Marine slugs
Diunduh dari: facstaff.gpc.edu/~apennima/ENVS/Biodiversity.ppt
Manfaat Biodiversitas
Berapa besar biodiversitas1.7—2.0 million speciesEstimates to 100 million
Diunduh dari: facstaff.gpc.edu/~apennima/ENVS/Biodiversity.ppt
Biodiversitas
Dimana biodiversitas?– Everywhere
• Every continent and habitat has unique life forms
– Concentrated in the tropics
• Panama: > 500 species of breeding birds
• Arctic: 50-100 species– Dense concentrations
Diunduh dari: facstaff.gpc.edu/~apennima/ENVS/Biodiversity.ppt
Biodiversitas
Kepunahan & Reduksi Populasi– Perburuan & Panen
berlebihan• Tiger• Dodo• Whales• Sharks
– Kehilangan Habitat
Diunduh dari: facstaff.gpc.edu/~apennima/ENVS/Biodiversity.ppt
Ancaman Biodiversitas
• Extinction and population reductions– Pollution– Climate change– Invasive species
Diunduh dari: facstaff.gpc.edu/~apennima/ENVS/Biodiversity.ppt
Ancaman Biodiversitas
• How can we protect biodiversity– Stop overharvesting
• Sustainable yield• Hunting & fishing laws
(every state ?)– in developing nations ?
– Protect habitat • Refuges, parks, preserves
– Endangered Species Act
Diunduh dari: facstaff.gpc.edu/~apennima/ENVS/Biodiversity.ppt
Proteksi Biodiversitas
• Refuges, parks, preserves– How big should refuges be?– Where should they be?– McArthur & Wilson “Theory of Island
Biogeography”• colonization rate• extinction rate (local)• predicts number of species
Diunduh dari: facstaff.gpc.edu/~apennima/ENVS/Biodiversity.ppt
Proteksi Biodiversitas
• Effect of island size • Effect of island distance
Diunduh dari: facstaff.gpc.edu/~apennima/ENVS/Biodiversity.ppt
Proteksi Biodiversitas
McArthur & Wilson: “Teori Biogeografi
Pulau”
– Laju Kolonisasi– Laju Kepunahan (lokal)– predicts number of
species
Diunduh dari: facstaff.gpc.edu/~apennima/ENVS/Biodiversity.ppt
Proteksi Biodiversitas
Biogeografi Pulau:Ukuran Pulau memprediksi jumlah spesies
Diunduh dari: facstaff.gpc.edu/~apennima/ENVS/Biodiversity.ppt
Proteksi Biodiversitas
Biogeografi Pulau– Everyplace is an island– Fragmentasi Habitat
• Smaller fragments hold fewer species
Diunduh dari: facstaff.gpc.edu/~apennima/ENVS/Biodiversity.ppt
Proteksi Biodiversitas
BIODIVERSITAS EKOSISTEM
Diunduh dari: http://www.environmentabout.com/820/ecosystem-biodiversity-and-types-of-biodiversity ……………… 4/12/2012
ECOSYSTEM BIODIVERSITY implies the existence of different species within an ecosystem. It
can also be defined as the degree of variations among the life forms in an ecosystem or planet.
ECOSYSTEM DIVERSITY is the variety of different natural systems or ecosystems in a
particular area.
Examples of ecosystem diversity are deserts, forests, wetlands, rain-forests, marine ecosystems etc.
What is biodiversity?
• OED: “biodiversity Ecol., diversity of plant and animal life, as represented by the number of extant species”
• Ricklefs & Miller: Biodiversity includes a number of different levels of variation in the natural world: genetic, species, ecosystem
• Begon et al. “The term may be used to describe the number of species, the amount of genetic variation or the number of community types present in an area”.
Tetapi .......… sebagian terbesar penelitian fokus pada diversitas spesies
Diunduh dari: www.geos.ed.ac.uk/homes/mwilliam/Biodiversity1.ppt
Apakah Biodiversitas mempengaruhi fungsi-fungsi
ekosistem ?
Diunduh dari: www.geos.ed.ac.uk/homes/mwilliam/Biodiversity1.ppt
Konsekwensi fungsional dari Biodiversitas:
Numbers and Kinds of Species
Organismal
traits
Ecosystem Processes
Diunduh dari: www.geos.ed.ac.uk/homes/mwilliam/Biodiversity1.ppt
Traits & Fungsi Ekosistem
1. Traits may mediate energy and material flow directly
2. Traits may alter abiotic conditions (limiting resources, disturbance, microclimate)
Diunduh dari: www.geos.ed.ac.uk/homes/mwilliam/Biodiversity1.ppt
Ekspresi Trait ditentukan oleh:
1. Species richness2. Species evenness3. Species composition4. Species interaction5. Temporal and spatial variation
Diunduh dari: www.geos.ed.ac.uk/homes/mwilliam/Biodiversity1.ppt
0.0 0.4 0.8 1.2 1.6 2.0 2.40.0
0.4
0.8
1.2
1.6
2.0
2.4
2.8
3.2r2=0.93
Tot
al fo
liar
N (
g m-2
gro
und
area
)
LAI
Diunduh dari: www.geos.ed.ac.uk/homes/mwilliam/Biodiversity1.ppt
The Ecosystem/Ecology Divide
1. Key ecosystem types in Arctic tundra show clear differences in key species and functional types
2. But at the ecosystem level there are clear patterns in the landscape irrespective of species composition
3. Bulk measures like LAI and foliar N are good descriptors of process rates
4. Dengan demikian, Apakah species sangat penting?
Diunduh dari: www.geos.ed.ac.uk/homes/mwilliam/Biodiversity1.ppt
Kekayaan Species & Fungsi Ekosistem : Theory
1. If niches are complementary, adding species could increase process rates linearly
2. As niches overlap the response should saturate
Diunduh dari: www.geos.ed.ac.uk/homes/mwilliam/Biodiversity1.ppt
Niche differentiation and productivity.
a. A simple model — the 'snowballs on the barn' model — of niche
differentiation and coexistence. The range of conditions in which each species can exist is shown with a
circle, the position of which is defined by its centre. By randomly
choosing locations for various numbers of circles (species), it is possible to calculate the effect of diversity on the 'coverage' of the
heterogeneous habitat. The amount of such coverage is proportional to
community biomass.b. Results of simulations
(triangles) and of an analytical solution (solid curve) to the effects
of diversity on community productivity for the snowballs on
the barn model
From: Tilman (2000), Nature.Diunduh dari: www.geos.ed.ac.uk/homes/mwilliam/Biodiversity1.ppt
(A) Dependence of 1996 aboveground plant biomass (that is, productivity) (mean and SE) on the number of plant species seeded into the 289 plots.
(B) Dependence of 1996 above-ground plant biomass on the number of functional groups seeded into each
plot. Curves shown are simple asymptotic functions fitted to treatment means. More complex curves did not provide significantly better fits
From: Tilman et al. (1997) Science
Diunduh dari: www.geos.ed.ac.uk/homes/mwilliam/Biodiversity1.ppt
Hypothesized mechanisms involved in biodiversity
experiments using synthetic communities. Sampling effects are involved in
community assembly, such that communities that have more species have a greater probability of containing a
higher phenotypic trait diversity. Phenotypic
diversity then maps onto ecosystem processes through
two main mechanisms: dominance of species with
particular traits, and complementarity among
species with different traits. Intermediate scenarios
involve complementarity among particular species or
functional groups or, equivalently, dominance of
particular subsets of complementary species.
From: Loreau et al (2001) Science
Diunduh dari: www.geos.ed.ac.uk/homes/mwilliam/Biodiversity1.ppt
Kemerataan Species
1. Human effects on species more commonly involve alteration of relative abundance than extinction
2. Little research on importance of evenness of function so far
3. Future richness experiments should include evenness effects
Diunduh dari: www.geos.ed.ac.uk/homes/mwilliam/Biodiversity1.ppt
Komposisi Species
• Species mediate pathways of energy and material flow
• Examples: Introduced species can alter patterns of ecosystem processes
Diunduh dari: www.geos.ed.ac.uk/homes/mwilliam/Biodiversity1.ppt
Species introduksi dapat mengubah pola proses-proses ekosistem
1. Introduction of N-fixing tree Myrica faya to N-limited Hawaiian forests led to 5-fold increase in N inputs
2. Dampak signifikan terhadap struktur dan fungsi hutan
Vitousek et al. (1987) ScienceDiunduh dari: www.geos.ed.ac.uk/homes/mwilliam/Biodiversity1.ppt
• Introduction of deep-rooted salt cedar (Tamarix sp.) to Mojave and Sonaran deserts resulted in:– Increased water accessed by vegetation– Increased surface litter and salts– Inhibited many native species, reduced
biodiversity
Berry (1970)Diunduh dari: www.geos.ed.ac.uk/homes/mwilliam/Biodiversity1.ppt
Species introduksi dapat mengubah pola proses-proses ekosistem
• Introduction of Agropyron cristatum, tussock grass, to US Great Plains– Reduced allocation to roots compared to
native grasses– Soil N levels reduced, and 25% less total soil C
compared to native prairie soil
Christian & Wilson (1999)Diunduh dari: www.geos.ed.ac.uk/homes/mwilliam/Biodiversity1.ppt
Species introduksi dapat mengubah pola proses-proses ekosistem
• Introduction of Bromus tectorum, cheatgrass, to western US– Fire frequency increased by a factor of 10 in the
>40 million ha it now dominates
Whisenant (1990)Diunduh dari: www.geos.ed.ac.uk/homes/mwilliam/Biodiversity1.ppt
Species introduksi dapat mengubah pola proses-proses ekosistem
Interaksi Species• Mutualism• Trophic interaction
– Predation– Parasitism– Herbivory
• Competition
Diunduh dari: www.geos.ed.ac.uk/homes/mwilliam/Biodiversity1.ppt
Mutualism
1. N-fixation in plant-microbe symbiosis2. Plant-mycorrhizal associations
1. Both increase production and accelerate succession
3. Decomposition is driven by highly integrated consortia of microbes
Diunduh dari: www.geos.ed.ac.uk/homes/mwilliam/Biodiversity1.ppt
STUDI KASUS
Mycorrhizal fungal diversity determines plant
biodiversity, ecosystem variability and productivity
Diunduh dari: www.geos.ed.ac.uk/homes/mwilliam/Biodiversity1.ppt
van der Heijden 1998Experiment 2 Diunduh dari: www.geos.ed.ac.uk/homes/mwilliam/Biodiversity1.ppt
Komunitas mikroba: Semakin beragam semakin efisien
Soil microbial functional diversity (Shannon index H')
and metabolic quotient (qCO2 = soil basal
respiration/soil microbial biomass) correlate inversely.
A higher diversity in the organic plots is related to a
lower qCO2, indicating greater energy efficiency of the more diverse microbial
community. The Shannon index is significantly different
between both conventional systems (CONFYM,
CONMIN) and the BIODYN system, the qCO2, between
CONMIN and BIODYN (P < 0.05).
Diunduh dari: www.geos.ed.ac.uk/homes/mwilliam/Biodiversity1.ppt Maeder 2002
Interaksi Trophik
• Modify fluxes of energy and materials• Influence abundance of species that control
these fluxes– e.g., predator removal can lead to a cascade of
ecological effects
Diunduh dari: www.geos.ed.ac.uk/homes/mwilliam/Biodiversity1.ppt
(A) Changes in sea otter abundance over time at several islands in the Aleutian archipelago and concurrent changes in (B) sea urchin biomass, (C) grazing intensity, and (D) kelp density measured from kelp forests at Adak Island. Error bars in (B) and (C) indicate 1 SE. The proposed mechanisms of change are portrayed in the marginal cartoons--the one on the left shows how the kelp forest ecosystem was organized before the sea otter's decline and the one on the right shows how this ecosystem changed with the addition of killer whales as an apex predator. Heavy arrows represent strong trophic interactions; light arrows represent weak interactions.
Estes et al. (1998) ScienceDiunduh dari: www.geos.ed.ac.uk/homes/mwilliam/Biodiversity1.ppt
Interaksi Trophik
1. All types of organisms must be considered in understanding biodiversity effects
2. Interactions among species must be considered
3. Changes in interactions can alter traits expressed by species, so presence/absence of species is insufficient to predict impact
Diunduh dari: www.geos.ed.ac.uk/homes/mwilliam/Biodiversity1.ppt
Biodiversity & Jasa Ecosystem
1. Ecosystem services are defined as the processes and conditions of natural ecosystems that support human activity and sustain human life
2. E.g., maintenance of soil fertility, climate regulation, natural pest control
3. E.g., flows of ecosystem goods such as food, timber and freshwater
Diunduh dari: www.geos.ed.ac.uk/homes/mwilliam/Biodiversity1.ppt
Valuasi Biodiversitas
1. Techniques used include direct valuation based on market prices, and estimates of what individuals are willing to pay to protect endangered wildlife
2. Valuation of marginal losses that accompany specific biodiversity changes are most relevant to policy decisions
3. Predictions are highly uncertain
Diunduh dari: www.geos.ed.ac.uk/homes/mwilliam/Biodiversity1.ppt
Apa pengaruh diversitas tumbuhan thd proses-proses ekosistem?
Plant community composition = IDENTITY
Diversitas Tumbuhan: 1. Genetic2. Population3. Species4. Functional group of species5. Habitat
Plant diversity = RICHNESSDiunduh dari: www.biology.ufl.edu/.../Diversity%20and%20ecosystems,%2011-3-10.p...
Climate
Relief(Topography)
Parent material
Time
Organisms
Ecosystemstructure and
function
State Factors
Ecosystem = (Cl, O, R, P, T)
Diunduh dari: www.biology.ufl.edu/.../Diversity%20and%20ecosystems,%2011-3-10.p...
Mengapa kita peduli ?• Understand a state factor control over
ecosystem variation: • in space• in time
Memahami dampak aktivitas manusia:• Habitat destruction and
extinction• Simplification through
management• Biological invasions
Diunduh dari: www.biology.ufl.edu/.../Diversity%20and%20ecosystems,%2011-3-10.p...
Variation in key plant traits can cause species to differ in their effects on ecosystem processes
• Trophic structure
• Biogeochemical cycles
• Disturbance regime
• Biophysical processes
Diunduh dari: www.biology.ufl.edu/.../Diversity%20and%20ecosystems,%2011-3-10.p...
Functional types are a useful simplification
• Life forms often make useful groups
• Groups of species that have a similar influence on an ecosystem process
• Relevant grouping depends on process of interest
• Makes it possible to represent aspects of diversity in models
Diunduh dari: www.biology.ufl.edu/.../Diversity%20and%20ecosystems,%2011-3-10.p...
Identitas Species : How does who’s there affect ecosystem processes?
Siklus N ….…
• N fixation• Space and time of N uptake• Species of N used• Turnover time and allocation• Litter quality
Diunduh dari: www.biology.ufl.edu/.../Diversity%20and%20ecosystems,%2011-3-10.p...
Diunduh dari: www.biology.ufl.edu/.../Diversity%20and%20ecosystems,%2011-3-10.p...
Growth
Quality litter
Nutrient mineralization
+
Growth
Quality litter
Nutrient mineralization
+
Plant litter traits can reinforce site nutrient
availability
Diunduh dari: www.biology.ufl.edu/.../Diversity%20and%20ecosystems,%2011-3-10.p...
Wedin and Tilman 1990Diunduh dari: www.biology.ufl.edu/.../Diversity%20and%20ecosystems,%2011-3-10.p...
Kekayaan Spesies = Species richnessHow does species number affect ecosystem
processes?
Is there an effect of diversity per se that is independent of
identity?
Diunduh dari: www.biology.ufl.edu/.../Diversity%20and%20ecosystems,%2011-3-10.p...
Tilman et al. 1997
Production: +, saturating
Changes in diversity have their largest
effects at low diversity
Diunduh dari: www.biology.ufl.edu/.../Diversity%20and%20ecosystems,%2011-3-10.p...
Mekanisme-mekanisme
1. Complementary resource use: Species = more complete resource useNiche differentiation, niche partitioning
2. Sampling effect: Species = probability of getting spp. with
strong effects on processes
How can we differentiate between these mechanisms?
Diunduh dari: www.biology.ufl.edu/.../Diversity%20and%20ecosystems,%2011-3-10.p...
Experiment: Menanam spesies secara Monokultur dan Campuran
1. Complementary resource use: Production in mixture >> production in
monocultureSynergy: “Overyielding”
2. Sampling effect: Production in mixture = production in
monocultureFew well-controlled empirical tests have
manipulated richness independent of composition
Diunduh dari: www.biology.ufl.edu/.../Diversity%20and%20ecosystems,%2011-3-10.p...
Tilman et al. 1997
1. Functional diversity explained the greatest amount of variation in plant biomass
2. When functional diversity was included, species diversity had no effect
Doesn’t matter how many species, only how many
functional groups
Diunduh dari: www.biology.ufl.edu/.../Diversity%20and%20ecosystems,%2011-3-10.p...
Tilman et al. 1997
Effects of functional diversity were caused by
presence or absence of key functional groups
Productivity = C4 grasses, legumes
Plant %N = legumesSoil NO3
- = C4 grasses
Overyielding was also observed:
C4 grasses yielded more in high then in
low diversity treatments
Diunduh dari: www.biology.ufl.edu/.../Diversity%20and%20ecosystems,%2011-3-10.p...
References• Chapin et al (2000) Consequences of changing biodiversity.
Nature 405: 234-242• Tilman, Wedin and Knops (1996) Productivity and sustainability
influenced by biodiversity in grassland ecosystems. Nature 379: 718-720
• Naeem & Li (1997) Biodiversity enhances ecosystem reliability. Nature 390:507-509
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Diunduh dari: www.geos.ed.ac.uk/homes/mwilliam/Biodiversity1.ppt
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