analisis biodiversitas agroekosistem

ANALISIS BIODIVERSITAS AGROEKOSISTEM

Disajikan : soemarno jurs tanah fpub des 2013

Mk. Manajemen Agroekosistem

LINGKUP KAJIAN

Pengelolaan Agroekosistem, Kegunaannya &

Kualitasnya

1. Pengertian DIVERSITAS2. Dimensi dan skala diversitas3. Diversitas, stabilitas dan

sustainability 4. Manfaat diversitas5. Pengembangan diversitas6. Teknik peningkatan diversitas7. Evaluasi tingkat diversitas

Diversitas = keanekaragaman

Diversitas ~ konsep multidimensi yang menggambarkan lebih dari 1 macam grup, berkaitan dengan perbedaan dan susunannya

Perbedaan dari segi: Jumlah (abundance) dan jenis (kategori)

Ukuran, satu jenis ukurannya lebih kecil dari pada jenis yang lain dalam kategori yang sama

Perbedaan Jumlah yang menggambarkan strukturnya

Sumber: Diversitas dan Stabilitas Agroekosistem. Kurniatun Hairiah. 2010. Bahan Kuliah Agroekologi. Jurusan Tanah, FPUB

Diversitas Diversity is a multi-dimensional concept, not a

single scalar. It describes an assemblage with >1 items, and relates to numbers of different kinds of items, their differences and configuration. Differences: properties and abundances (numbers) of

types (categories) Differences in properties among items within types

are smaller than those between them. Differences in abundances reveal assemblage

structure.


Diversitas


“The variability among living organisms from all sources including, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems.”

Definisi: Keaneka ragaman Hayati (Biological Diversity)

"Keanekaragaman antar makhluk hidup dari berbagai sumber termasuk diantaranya daratan (terrestrial),

perairan (marine) dan ekosistem perairan lainnya; ini termasuk pula keaneka-ragaman dalam spesies, antar

spesies dan dalam ekosistem”.


Definisi Keanekaragaman Hayati (Biological Diversity)

ab

b

ba

a

aaa a

aa

g

“Keragamaman organisma hidup pada semua

kompleks ekosistem (daratan, perairan),

termasuk didalamnya adalah:

keanekaragaman dalam species yang sama, antar spesies dan ekosistem”.

Scaling up from the plot to the landscape level


Dimensi diversitas

Species1

Genetik2

Vertikal3

Horisontal4

Struktural5

Fungsional6

Temporal7


Jumlah spesies yang berbeda dalam suatu sistem

1. Dimensi Spesies


Tingkat diversitas genetik dalam suatu sistem

1. Tingkat spesies2. Antar spesies

2. Dimensi Genetik


Jumlah level horisontal yang berbeda dalam

satu sistem

3. Dimensi Vertikal

Strata 1=tumbuhan bawah

Strata 2

Strata 3

Strata 4


Pola distribusi spasial organisme-organisme dalam suatu sistem

4. Dimensi Horisontal


5. Dimensi Struktural

6. Dimensi Fungsional

Jumlah lokasi (niches, Trophic roles) dalam suatu sistem

Interaksi dari adanya kompleksitas, Aliran energi, siklus materi diantara komponen penyusun


7. Dimensi Temporal

Tingkat heterogenitas perubahan siklus per waktu (harian, musiman dll) dalam satu sistem


www.apsnet.org/online/feature/nematodes(a) keragaman nematoda,

b) Diversitas nematoda

(c) index maturity

(d) Indeks struktur

(e) bacterivorous nematode,

(f) fungivorous nematode,

(g) omnivorous nematode inside the sunn hemp bag;

(h) percentage of herbivore dalam B, SI and SO.

Nilai yang diikuti dengan huruf berbedabaik pada grafik dengan garis tunggal maupun jamak berbeda nyata pada P < 0.05 according to Waller-Duncan k-ratio (k = 100) t-test.


SKALA DIVERSITAS

•α Diversitas

•β Diversitas

•γ Diversitas


Skala Diversitas

ab

b

b

aa

aaa a

aa

g

α= Variasi spesies dalam sebagian kecil dari komunitas

β= Diversitas spesies pada berbagai habitat atau komunitas

δ=Diversitas spesies pada skala lebih besar, mis. Daerah pegunungan atau daerah lembah


α Diversitas

• Tingkat plot

• Area kecil

• 1 komunitas


• Beta – Lamanya hidup berbagai jenis pada berbagai kondisi lingkungan

16.14

Perbedaan ketinggian tempat mempengaruhi Diversitas Vegetasi

β Diversitas


Skala Biodiversitas

1 31 1 3 3

1 spesies per box =α diversitas rendah

3 macam box = β diversitas tinggi

3 spesies per box =α diversitas tinggi

1 macam box = β diversitas rendah


β Diversitas : Diversitas Penggunaan Lahan dalam Lansekap (Mosaik lansekap)


Peningkatan diversitas

•Diversifikasi relung (niche)•Modifikasi habitat•Kompetisi•Pembagian sumber makanan•Perkembangan mutualisme

melalui beberapa proses antara lain:


Changes in species diversity and biomass during succession

MaturityDisturbanceTime

Ecosystem biomass

Species Diversity


Diversity and stability

Stability

Spec

ies

dive

rsity

Stabilitas: tidak ada gejolak populasi organisma dalam suatu

ekosistem atau disebut juga kondisi yang stabil


Mengapa biodiversitas penting?


Manfaat Biodiversitas dalam Agroekosistem

• Keragaman mikrohabitat• Keberlanjutan Produktivitas tanaman, mis. Rizhobium,

mikoriza• Mengurangi gulma• Mempertahankan predator/herbivore• Meningkatkan efisiensi serapan hara• Mengurangi resiko gagal panen• Mengrangi resiko kepunahan flora+fauna• Mempertahankan biodiversitas dalam tanah dan layanan

lingkungannya


Pengembangan Diversitas


Diversitas Bentukan Petani• Tumpangsari• Gulma alami• Tumbuhan Pagar• Rotasi

Peningkatan Diversitas Biotic• Predator herbivore alami• Organisma tanah yg menguntungkan• Allelopathic pencegah gulma• Penambat N

Pengembangan Biodiversitas

Perbaikan kondisi abiotic• Ketersediaan hara meningkat• Perbedaan mikrohabitat• Peningkatan BOT• Perbaikan Struktur Tanah

Perbaikan Kualitas Sistem• Interaksi sistem yang saling menguntungkan

(mutualisme)• Siklus hara internal• Pengendalian hama secara alami• Menghindari kompetisi• Efisiensi penggunaan hara• Stabilitas • Reduksi gagal panen(Gliessman, 2000, p 228)


Contoh: Rhizobium, Legume & siklus N

Rhizobium memperoleh gula dari tanaman inangnya, Tanaman inang memperoleh N dari Rhizobium. Tanah semakin miskin N, fiksasi N

semakin banyakSumber: Diversitas dan Stabilitas Agroekosistem. Kurniatun Hairiah. 2010. Bahan Kuliah Agroekologi. Jurusan Tanah,

FPUB

Contoh: Rhizobium, Legume & siklus N

Nodule akar

Nodule batangSumber: Diversitas dan Stabilitas Agroekosistem. Kurniatun Hairiah. 2010. Bahan Kuliah Agroekologi. Jurusan Tanah, FPUB

Symbiotic: bacteria and plants (e.g. legumes + rhizobium

Sengon

Bacteria require plant for growing; plant gains ‘free’ source of available N

Mycorrhiza

Peningkatan serapan P:

• memperluas daerah jelajah akar ~ mycellium

• P tidak tersedia P tersediaSumber: Diversitas dan Stabilitas Agroekosistem. Kurniatun Hairiah. 2010. Bahan Kuliah Agroekologi. Jurusan Tanah,

FPUB

Jml. Spesies Mikoriza

0.8

0.6

0.4

0 146 102

R2=0.67

Inde

x D

iv. T

anam

an120

100

80

0 146 102

R2=0.69


BK

taju

k, g

6

4

2

0 146 102

R2=0.60


Panj

ang

Hyp

ha,

m g

-1 ta

nah

Pengaruh manipulasi Arbuscular Micorryzal (AM) terhadap diversitas tanaman, biomasa tajuk dan panjang hypha

(Bardget, 2005; hal 106)


Teknik peningkatan diversitas dalam sistem

pertanian• Introduksi spesies baru• Re-strukturisasi spesies lama• Menambah spesies ~ Meningkatkan input• Mengendalikan diversitas ~ mengontrol input


Contoh pola tanam

•Tumpangsari = Intercropping•Budidaya pagar = Alley cropping•Penutup tanah = Cover crop•Rotasi tanam = Crop rotation•Bera (fallow)•TOT (Tanpa olah tanah) = No tillage•Organik (masukan organik tinggi, sedikit

masukan kimia)•Agroforestri = Wanatani


mudah dan murah

tambahan hara

bebas hama/penyakit

Foto: M van Noordwijk & K Hairiah

Pembukaan lahan pertanian


People

Imperata

1 2 3 4 5 6 7 8 9

Human migration

A B C D

A. Forest margin: slash & burn

B. Shorter fallows ==>soil degradation

C. Imperata fire climax - people move out

D. Imperata rehabilitation via Agroforestry


Tumpangsari tanaman semusim

Jagung + Ubijalar


Pakuan Ratu, Maret 2000(Foto: Kurniatun Hairiah)

Tumpangsari pohon karet dan ubikayu


(Foto: Kurniatun Hairiah)

Lada dan GliricidiaSumber: Diversitas dan Stabilitas Agroekosistem. Kurniatun Hairiah. 2010. Bahan Kuliah Agroekologi. Jurusan Tanah,

FPUB

Pekarangan berbasis pohon Foto: Meine van Noordwijk


Analisis distribusi dan struktur komunitas

• Kepadatan populasi (K)

~ jumlah atau berat massa (biomasa) per unit contoh atau per satuan luas tanah, atau per satuan volume tanah atau per satuan penangkapan

Jumlah individu jenis A

K jenis A =

Jumlah unit contoh /luas/volumeCocok untuk pengukuran produktivitas tetapi TIDAK

COCOK untuk membandingkan antar komunitas !Sumber: Diversitas dan Stabilitas Agroekosistem. Kurniatun Hairiah. 2010. Bahan Kuliah Agroekologi. Jurusan Tanah,

FPUB

2. Kepadatan relatif (KR)

K jenis A

KR jenis A = x 100 %

Jumlah K semua jenis

3. Frekuensi kehadiran (Fr)

Untuk menunjukkan penyebaran jenis fauna pada satu habitat

Kepadatan spesies A relatif terhadap total spesies yang diamati

Fr jenis A = Jumlah unit dimana A ditemukan


Dominansi suatu spesies

• Indeks Nilai Penting, INP (Index of Important Value) (Suin, 1989)

INP = FR + KR

FR = Frekuensi kehadiran

KR = Kepadatan relatif


Nilai Index Diversitas menurut persamaan Shannon (Kennedy and Smith, 1995; Kindt and Burn, 2003:

ni = jumlah individu dari spesies i sampai dengan spesies ke s, n = jumlah total individu yang ditemukan pada suatu SPL.

H’ =-Σ (ni / n) ln (ni / n) I =1

s

Penilaian diversitas dalam komunitas di suatu SPL


Bagaimana mengevaluasi keuntungan dari tumpangsari?

LER (land equivalent ratio)

LER = Σ Ypi / Ymi

Ypi = Produksi yang diperoleh dari sistem tumpangsariYmi = Produksi yang diperoleh dari sistem monokultur

LER = 1.0 nggak berbeda produksi mono dan poliLER = 2.0 untuk mencapai produksi seperti yang di sistem polikultur dibutuhkan lahan sebanyak 2x lipat


0.801000800Tan. B

1.63Σ Ypi / Ymi

0.8312001000Tan. A

LERYP/ Ym

ProdMn

Ym, kg/ha

ProdTP

YP, kg/ha

Contoh: Penghitungan LER


Diversity-Stability HypothesisMcArthur (1955)

WHY ?

Diunduh dari: www.math.luc.edu/~tobrien/.../pres03b.ppt....... 8/12/2012

http://images.google.com/imgres?imgurl=http://diversity.e-consultation.org/wp-content/uploads/2006/04/diversity-is-imp-small.jpg&imgrefurl=http://diversity.e-consultation.org/blog/2006/04/04/live-from-the-field-13/&h=497&w=450&sz=38&hl=en&start=6&um=1&tbnid=etXOuM6CreDWDM:&tbnh=130&tbnw=118&prev=/images?q=+diversity+&svnum=10&um=1&hl=en

Ecologists describe distribution of diversity on a spatial scale in three classifications.

α The diversity of organisms within a selected habitat or sample.

β Index of the rate of increase of alpha as new habitats are sampled.

γ The full species diversity/ species richness.

Alpha, Beta, and Gamma diversity measures are Scale Dependent.

What’s that mean?Diunduh dari: www.math.luc.edu/~tobrien/.../pres03b.ppt....... 8/12/2012

Ecologist one studies:

One acre of land and calls this one habitat

measuring alpha diversity.

Ecologist two studies microbial organisms, therefore one acre of land would contain an infinite amount of microhabitats under his consideration. The one acre of land would be measuring Gamma Diversity.


http://images.google.com/imgres?imgurl=http://www.chrisdellavedova.com/wp-content/uploads/2007/10/scientist.gif&imgrefurl=http://www.chrisdellavedova.com/2007/10/26/apolitical-friday-workingman-blues/&h=708&w=631&sz=27&hl=en&start=7&um=1&tbnid=nxKq0slf-rkHJM:&tbnh=140&tbnw=125&prev=/images?q=Scientist&svnum=10&um=1&hl=en&sa=N

http://lh3.google.com/_fMWaTyAfYXk/RtxuYqMK2iI/AAAAAAAABcI/luj9NZm0i1E/s800/IMG_0454.JPG

http://images.google.com/imgres?imgurl=http://upload.wikimedia.org/wikipedia/commons/thumb/9/9b/Mad_scientist_transparent_background.svg/641px-Mad_scientist_transparent_background.svg.png&imgrefurl=http://commons.wikimedia.org/wiki/Image:Mad_scientist_transparent_background.svg&h=600&w=641&sz=102&hl=en&start=2&um=1&tbnid=1q0uhVouDFyvWM:&tbnh=128&tbnw=137&prev=/images?q=scientist&svnum=10&um=1&hl=en

What are the properties of the community that

can be measured to indicate its alpha diversity? The total number of species within

the sample although relative frequencies are

unknown. • Richness and Balance


There an infinite number of different mathematical functions to describe diversity indices by

encapsulating different aspects of the balance between richness

and balance.


Each of the Indices mention require the calculationof a Population Proportion Pi

S: the total number of species in the sample.Ni : the number of individuals in the ith species.

Total number of individuals in a sample may be calculated as: ∑N

The proportion made up by species i (denoted pi ) is given by: Pi: Ni ∕ ∑N

Procedure: Convert the count for each species in a sample to a proportion of the total number of individuals within the sample.


The Simpson Index• measures the probability that two consecutive random

samples from a population will find the same species.• The probability that a random sample from a population will

pick out a given species is assumed to be equal to that species’ contribution to the whole population.– Pi = Ni/∑N

• The probability of sampling species i in two consecutive samples is found as follows:– p(sampling species i twice) = pi * pi

– A more realistic model equation: • P(sampling species I twice) = Ni(Ni-1)/ ∑N(∑N-1)

• The probability of sampling any species twice in two consecutive samples can be found as: – P(sampling any species twice)= ∑(pi* pi)


Interpretasi Indeks Simpson

• If there is only one species, pi = 1, hence ∑(pi* pi) =1. This is called the zero diversity condition.

• As the number of species tends to infinity, ∑(pi* pi) tends to zero, which is the high diversity condition.

• Simpson’s index is usually altered to reverse the above arrangement. – D= 1-∑(pi* pi)

• So this equation calculate the probability of two consecutive samples will be of different species.

– D is the standard symbol for the Simpson index.


Indeks Shannon

• Most commonly used diversity index.

• H’= -∑pi x log(pi)

• H: Symbol for Shannon Index.• Negative sign (-) makes sure “f” value is received.

• Community with one species (Pi = 1.0), diversity is zero.

If a community with S # of species, maximum possible value of the Shannon index is log(S)- this occurs when all species occur at equal frequency.Diunduh dari: www.math.luc.edu/~tobrien/.../pres03b.ppt....... 8/12/2012

For ecological studies, logarithms base 10 are used.

• Converting between logarithms of different bases:

Loga(X)= Logb(X)/Logb(a)

• Combine + = H’(base2)= [-∑ pi x log10(pi)]/ log10(2) =

3.3219 x H’(base 10)


• Let us calculate the ratio of calculated diversity with maximum possible diversity for the number of species found.

E= H’/Hmax = [-∑pi x log(pi)]/ log(S)

• Does not matter what sort of logarithm is used.

• Reflects evenness of species distribution within sample.

• An equitability near zero shows the community to be dominated by one species.

• An equitability near 1.0 indicates an equal balance between all species.


EQUITABILITY

• Successional changes in community structure, such as a bare habitat where colonization starts with a few colonist species, followed by a gradual increase in numbers as new species arrive.

• First year: low-species diversity

• 281 individuals, 280 one species.

• Simpson diversity: 0.007

• Shannon diversity: 0.034


Interest: the effects of increased atmospheric pollution on the growth of coarse grasses.

Problem: high levels of nitrogen deposits due to ammonia release.

Effect: stimulates coarse grasses in preference to the rich community of low- growing, less vigorous herbs.

Five experimental plots: Brachypodium pinnatum was present, not dominant.

* different concentrations of nitrogen, phosphorus, & potassium fertilizers.

* increase in biomass, decrease in number of species.

Data summarized using Shannon index.


http://images.google.com/imgres?imgurl=http://bp0.blogger.com/_IxbPTJjEYxw/Rp6LEY9PWPI/AAAAAAAAB1k/NkJvWlPaqFo/s400/IMG_9562Wildcarrot.jpg&imgrefurl=http://stmargaretsphotodiary.blogspot.com/2007_07_15_archive.html&h=400&w=274&sz=32&hl=en&start=4&um=1&tbnid=vyCTzEUViqDiWM:&tbnh=124&tbnw=85&prev=/images?q=Dutch+Chalk+grasslands&um=1&hl=en&sa=N

Ecological Conclusion: Brachypodium pinnatum is able to flourish on high levels of nitrogen & low levels of phosphorus. The coarse grass was able to use its height to shade out other species therefore

1. Reducing Biodiversity

2. Reducing conservation value of habitat.


http://bp3.blogger.com/_IxbPTJjEYxw/Rp6NcI9PWVI/AAAAAAAAB2U/eWXs4EyqNFc/s400/IMG_9554Wheat.jpg

http://images.google.com/imgres?imgurl=http://bp1.blogger.com/_IxbPTJjEYxw/Rp6NTo9PWUI/AAAAAAAAB2M/m6CayNj9SMY/s400/IMG_9564flowers.jpg&imgrefurl=http://stmargaretsphotodiary.blogspot.com/2007_07_15_archive.html&h=267&w=400&sz=52&hl=en&start=3&um=1&tbnid=XvuS-GtUUSH3dM:&tbnh=83&tbnw=124&prev=/images?q=Dutch+Chalk+grasslands&um=1&hl=en&sa=N

• Used when the randomness of sampling is not guaranteed.

• HB= [ ln(N!)-∑ln(ni!) ] / N

• HB: Brillouin Index N: Total number of individuals in the sample ni: number of individuals of species

• Unlike the Shannon & the Simpson indices, this index varies with sample size

as well as with the relative proportions of species. Why?


Only calculates the proportion of the most common species in a sample:

d= Nmax/ N

D= [N-(∑ni2)1/2] / N-N1/2


analisis biodiversitas agroekosistem

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